HK1196704B - Led lamp, lighting device including led lamp, and method for controlling electric current of led lamp - Google Patents

Description

LED lamp, lighting device comprising same, and current control method for LED lamp

Technical Field

The present invention relates to an LED lamp capable of stabilizing the magnitude of a current flowing through an LED light emitting portion within a predetermined range even when the LED lamp is mounted in place of a fluorescent lamp of a constant power control inverter type lighting device that is commercially available, an illumination device including the LED lamp, and a current control method for the LED lamp.

Background

Conventionally, as a typical lighting device for a fluorescent lamp (generally referred to as a fluorescent lamp) which is generally used, there are various lighting devices for fluorescent lamps such as a glow starter type called a magnetic stabilizer, a quick starter type, or an inverter type called an electronic stabilizer.

In recent years, the inverter type fluorescent lamp lighting device, which has been particularly rapidly spread, is a device that converts an alternating current into a direct current and then generates a high voltage of a high frequency (20 kHz to 100 kHz) near a resonance frequency by an inverter circuit including a transistor, a capacitor, a choke coil, and the like.

The fluorescent lamp is lit by the high voltage, and then, the fluorescent lamp is stably lit at a low voltage by a current flowing in the fluorescent lamp.

Compared with the prior glow starting type, quick starting type and other magnetic stabilizers using a choke coil, the glow starting type, quick starting type and other magnetic stabilizers have the advantages of energy conservation, high efficiency, dual purposes of 50Hz/60Hz, low noise, no flicker and the like.

The following description refers to the accompanying drawings.

Fig. 15 (a) is a diagram showing an example of a glow starter type ballast, fig. 15 (b) is a diagram showing an example of a rapid start type ballast, and fig. 15 (c) is a diagram showing an example of an inverter type ballast.

The glow starter stabilizer shown in fig. 15 (a) is a type that can be lit within several seconds from the time of turning on a switch by preheating an electrode (also referred to as a filament, hereinafter the same) of a fluorescent lamp by a starter using a lighting tube (glow starter G), and is the most widely used type.

In addition, the quick start type ballast shown in fig. 15 (b) is a ballast used by combining with a quick start type lamp, and is of a type that lights up instantaneously simultaneously with preheating if a switch is turned on.

On the other hand, the stabilizer of the inverter type lighting device shown in fig. 15 (c) is of a type in which an AC current within an AC input voltage of 85 to 450V is converted into a dc current, and then the LED lamp is driven and lit at a high frequency as described above by an integrated circuit (see, for example, page 4 and fig. 2 of patent document 1).

In this case, the choke coil L is inserted in series with the LED lamp in order to smooth the current flowing through the LED lamp, but an electrolytic capacitor (not shown) is usually inserted in parallel with the LED lamp.

Fig. 16 is a diagram showing an example in which 2 fluorescent lamps are connected in series to the series rapid ballast.

Since 2 fluorescent lamps are connected in series and are lit by 1 stabilizer, the structure can be simplified and the lamp can be more economical than a flicker-free stabilizer of a type using two 1-lamp stabilizers.

When the power is input, the electrodes of the fluorescent lamp a and the fluorescent lamp B are preheated, and the starting capacitor has a high impedance, so that the voltage on the secondary side is not transferred to the normal discharge and becomes a micro-discharge state. The voltage drop across the starting capacitor due to the micro discharge current is applied to the fluorescent lamp B, and the discharge of the fluorescent lamp B is started.

If discharge occurs in both fluorescent lamps, the high-impedance starting capacitor is substantially in a non-operating state, and normal discharge occurs in both fluorescent lamps to maintain the lighting state.

Since the lamps are connected in series and discharged one by one, the fluorescent lamp having 2 lamps connected in series can be turned on by a relatively low secondary side voltage, but there is a disadvantage that both of them are not turned on when one fluorescent lamp is removed for power saving or one fluorescent lamp is cut off.

However, as a stabilizer of the inverter type lighting device (hereinafter, also referred to as an inverter type stabilizer or an electronic type stabilizer), not only an LED lamp but also a conventional fluorescent lamp is applied, and there are known a constant current control type in which a magnitude of a current flowing through a fluorescent lamp is controlled to be constant, and a constant power control type in which a magnitude of power supplied to a fluorescent lamp is controlled to be constant (for example, see patent documents 2 and 3).

[ patent document 1 ] Japanese patent application laid-open No. 2010-34012

[ patent document 2 ] Japanese patent application laid-open No. 2010-218961

[ patent document 3 ] Japanese patent laid-open No. 2002-15886

Disclosure of Invention

In recent years, LED lamps have been mounted on the above-described various types of stabilizers instead of conventional fluorescent lamps for reasons of energy saving, long lamp life, and the like.

In this case, the peak value and the frequency of the ac current input to the pair of input terminal portions of the LED lamp greatly differ depending on the type of the stabilizer of the lighting device to which the LED lamp is mounted, and therefore, it is necessary to use the LED lamp corresponding to each stabilizer.

For example, if the lighting device of the fluorescent lamp is a glow starter type or a rapid start type, the output (secondary side output) of the stabilizer is controlled by about AC200V in accordance with AC100V to 240V (50 Hz/60 Hz) input from the power supply side, but the frequency is the same as the frequency input from the power supply side because the control for increasing the frequency is not performed.

Therefore, in the LED lamp, the current is rectified into a direct current by an internal rectifier circuit so that an alternating current having a frequency equal to the frequency input from the power supply side can be used, and then the circuit configuration of the LED light emitting unit of the LED lamp (the configuration of a circuit connecting a plurality of LEDs, the same applies hereinafter) is fixed so that a desired illuminance is obtained, and the magnitude of the current flowing through each LED falls within a predetermined range.

Therefore, conventionally, when the ballast of the lighting device of the fluorescent lamp is of a glow start type or a rapid start type, each built-in LED can be lit by using a dedicated LED lamp that can be adapted to a lamp socket for the fluorescent lamp.

On the other hand, as described above, if the lighting device of the fluorescent lamp is of the inverter type, the constant current control or the constant power control is performed so that the output (secondary side output) of the stabilizer is controlled to a constant voltage of about AC280V (no load) and the frequency is within the range of 20kHz to 100kHz even if the power supply side input is AC100V to 240V (50 Hz/60 Hz), and therefore, the circuit configuration of the LED light emitting portion of the LED lamp is fixed so that the magnitude of the current flowing through each LED is within the predetermined range so as to obtain a desired illuminance.

Therefore, when the ballast of the lighting device of the fluorescent lamp is an inverter type, a circuit change work on the lighting device side is performed or a conversion adapter required for direct connection is applied so that electric power on the power supply side can be directly supplied to an AC/DC converter (rectifier circuit) built in the LED lamp without passing through the inverter type ballast (without performing a driving operation), and a corresponding measure is required on the lighting device side and the LED lamp side.

In addition, when the LED lamp is turned on by the inverter type, it is necessary to replace the lighting device incorporating the inverter type stabilizer and the LED lamp dedicated thereto in a kit.

As described above, the point at which selection of the LED lamp is rejected (confirmation of suitability) according to the mode of the lighting device, the point at which additional work such as circuit work and direct connection work is required on the lighting device side, and the like are necessary, and this causes the present situation of the work for introduction, the complexity of work period adjustment, and the like, and the increase in introduction cost associated therewith, from the user side.

That is, these have been obstacles to the adoption of LED lamps to conventional fluorescent lamp lighting devices in homes and work units.

As a result, since conventional fluorescent lamps are used as they are, they have become a major obstacle factor in market popularization of LED lamps that can contribute significantly to energy saving and long lamp life.

In addition, when an LED lamp is mounted on the constant power control type inverter-type stabilizer, for example, the output voltage of the inverter-type stabilizer is reduced and the output current is increased because the value of load impedance that limits the value of current flowing through the LED light emitting portion of the LED lamp is smaller than that of a fluorescent lamp. As a result, the magnitude of the current flowing through the LED lamp may be larger than a predetermined range, and thus an appropriate amount of light may not be obtained.

In addition, in order to drive fluorescent lamps of various rated powers, there are inverter-type stabilizers having various output power settings, and depending on the type of these inverter-type stabilizers, the magnitude of the current flowing through the LED lamp may not be stabilized within a predetermined range, and an appropriate amount of light may not be obtained. Specifically, the output voltage of the inverter-type stabilizer is fixed in a manner substantially proportional to the magnitude of the load impedance of the LED lamp, and the output current varies depending on the magnitude of the output voltage. As a result, the magnitude of the current flowing through the LED lamp may vary beyond a predetermined range, and an appropriate amount of light may not be obtained.

Accordingly, an object of the present invention is to provide an LED lamp, a lighting device including the LED lamp, and a current control method for the LED lamp, which can stabilize the magnitude of a current flowing through an LED light emitting portion within a predetermined range by exchanging the ballast of a fluorescent lamp lighting device (which may be an LED lamp) with a fluorescent lamp (which may be an LED lamp) mounted in the past even if the ballast is of a constant power control inverter type.

The present invention provides an LED lamp including a pair of input terminal portions, a rectifier circuit portion rectifying an alternating current inputted from the outside to the pair of input terminal portions into a direct current, and an LED light emitting portion emitting light by energization of the direct current outputted from the rectifier circuit portion, the LED lamp including: a variable inductance section through which an alternating current flows in a circuit between the pair of input terminal sections and the rectifier circuit section, the alternating current flowing from one of the pair of input terminal sections to the other of the pair of input terminal sections through the rectifier circuit section; a current detection unit that detects the magnitude of a direct current flowing into the LED light emitting unit in a circuit between the rectifier circuit unit and the LED light emitting unit; and an inductance variable control unit for varying the inductance value of the variable inductance unit in accordance with the magnitude of the direct current detected by the current detection unit.

According to this LED lamp, even if the ballast of the fluorescent lamp lighting device is a constant power control inverter type ballast, the inductance of the variable inductance part is changed by the inductance variable control part in accordance with the magnitude of the current detected by the current detection part, so long as the ballast is exchanged with a fluorescent lamp (or may be an LED lamp) mounted in the front, and the output voltage is fixed so as to be substantially proportional to the value. As a result, the magnitude of the current flowing through the LED light-emitting portion can be stabilized within a predetermined range.

For example, when the magnitude of the current flowing through the LED light emitting portion is smaller than a predetermined range, by reducing the inductance value of the variable inductance portion, the output voltage of the constant power control inverter-type stabilizer is reduced, the output current is increased, and the magnitude of the current flowing through the LED light emitting portion can be stabilized within the predetermined range. On the other hand, when the magnitude of the current flowing through the LED light emitting portion is larger than the predetermined range, by increasing the inductance value of the variable inductance portion, the output voltage of the constant power control inverter-type stabilizer is increased, the output current is decreased, and the magnitude of the current flowing through the LED light emitting portion can be stabilized within the predetermined range. That is, a desired effect is obtained by utilizing the characteristic of the control system in which constant power is supplied to the LED lamp side in the constant power control type inverter stabilizer.

In addition to the above configuration, the LED lamp may further include a threshold element for passing an ac current flowing from one of the pair of input terminal portions to the other input terminal portion through the rectifier circuit portion in a circuit between the pair of input terminal portions and the rectifier circuit portion, wherein both ends of the threshold element are short-circuited after a predetermined time has elapsed since an ac current exceeding a predetermined threshold value is externally input to the pair of input terminal portions, and the variable inductance control portion may vary the inductance value of the variable inductance portion in accordance with a magnitude of the dc current detected after both ends of the threshold element are short-circuited.

For example, according to the type of the constant power control type inverter-type stabilizer, at the start of output, in order to grasp the state of a fluorescent lamp (for example, check whether or not the fluorescent lamp is mounted on the load side), the output voltage is set to a small amount of current lower than the rated value and an appropriate amount of light is not obtained, the magnitude of the output current at that time is monitored, and then the output voltage is increased to a predetermined range, and then the constant power control is performed.

However, according to this configuration, since both ends of the threshold element are short-circuited after a predetermined time has elapsed since an ac current exceeding a predetermined threshold value is inputted to the pair of input terminal portions from the outside, and the inductance value of the variable inductance portion is variable according to the magnitude of the dc current flowing through the LED light emitting portion after both ends of the threshold element are short-circuited, even in the inverter-type stabilizer of this type, only the current (current in a normal lighting state) flowing through the LED light emitting portion to be detected is detected without performing erroneous control.

In addition to the above configuration, the LED lamp may further include a circuit interrupting portion capable of interrupting, in a circuit between the pair of input terminal portions and the rectifier circuit portion, an alternating current flowing from one of the pair of input terminal portions to the other input terminal portion through the rectifier circuit portion, wherein the circuit interrupting portion interrupts the alternating current when a magnitude of the direct current detected by the current detecting portion exceeds a predetermined upper limit value or falls below a predetermined lower limit value.

With this configuration, for example, an overcurrent flows into the LED lamp due to aging or some abnormality on the stabilizer side, and the flow of an ac current input from the outside to the pair of input terminal units to the rectifier circuit unit can be cut off in terms of safety. On the contrary, even when the magnitude of the detected dc current is very small due to some abnormality such as the state of mounting the LED lamp to the stabilizer or the electrical connection failure, the ac current input from the outside to the pair of input terminal units can be cut off from flowing to the rectifier circuit unit in terms of safety.

In addition to the above configuration, the LED lamp may further include a PWM control unit that is provided in the circuit between the rectifier circuit unit and the LED light emitting unit and is capable of PWM-controlling the current flowing into the LED light emitting unit according to a duty ratio, wherein the PWM control unit switches between a case of performing PWM control of the current flowing into the LED light emitting unit and a case of not performing PWM control of the current flowing into the LED light emitting unit according to a frequency of an external alternating current input to the pair of input terminal units, and the current detection unit detects a magnitude of a direct current flowing into the LED light emitting unit when the PWM control unit does not perform the PWM control, and the inductance variable control unit may vary an inductance value of the variable inductance unit according to the magnitude of the direct current.

According to this configuration, regardless of whether the ballast of the fluorescent lamp lighting device is of a glow start type, a quick start type, or an inverter type, the fluorescent lamp lighting device can be turned on as a illuminable lighting by PWM control using pulse driving, as long as it is replaced with a fluorescent lamp (or an LED lamp) installed from the front. In addition, when the LED lighting device is mounted in an inverter-type stabilizer, that is, when the PWM control unit does not perform PWM control, the magnitude of the current flowing through the LED lighting unit can be stabilized within a predetermined range by this configuration.

In other words, as long as the stabilizer of the fluorescent lamp lighting device is of a glow start type or a rapid start type, and the frequency of the ac current inputted from the pair of input terminal units is as low as the commercial frequency 50Hz/60Hz, the PWM control unit of the LED lamp plays a role in stabilizing the current flowing through the LED light emitting unit. On the other hand, when the frequency of the ac current input from the pair of input terminals is as high as 20kHz to 100kHz as in the inverter type, the inductance value of the variable inductance portion is variable according to the magnitude of the dc current flowing through the LED light emitting portion, and this stabilizer acts to stabilize the current flowing through the LED light emitting portion.

In addition, according to the LED lamp, in addition to the above configuration, the PWM control section performs PWM control of the current flowing through the LED light emitting section by pulse driving at a frequency higher than the predetermined frequency when the frequency of the external ac current input to the pair of input terminal sections is lower than the predetermined frequency, and does not perform PWM control of the current flowing through the LED light emitting section when the frequency of the external ac current input to the pair of input terminal sections is higher than the predetermined frequency.

With this configuration, regardless of whether the ballast of the fluorescent lamp lighting device is of a glow start type, a quick start type, or an inverter type, if it is replaced with a fluorescent lamp (or an LED lamp) installed from the front, the fluorescent lamp lighting device can be turned on as a illuminable lighting by performing pulse driving at a frequency higher than a predetermined frequency.

Therefore, it is necessary to select (confirm suitability) a point of the LED lamp depending on the type of the lighting device, or a point of the lighting device side requiring additional work such as circuit work and direct connection work, and the like, and it is easy to eliminate the complexity of the current situation of the work for introduction, such as checking and adjusting the work period, and the introduction cost associated therewith from the user side.

As a result, the LED lamp does not interfere with the conventional fluorescent lamp lighting device (which may be an LED lighting device) used in homes and work units.

In addition, LED lamps that can contribute significantly to energy saving and longer lamp life have been widely used in the market.

For example, if the ballast of the fluorescent lamp lighting device is of a glow starter type or a rapid starter type, the frequency of the ac current input from the pair of input terminal portions is 50Hz/60Hz of the commercial frequency.

Therefore, the PWM control unit PWM-controls the current flowing through the LED light emitting unit with the drive pulse having a frequency at least higher than a predetermined frequency (for example, 5 kHz), so that the current flowing through the LED light emitting unit can be repeatedly turned ON and OFF at a high speed, and a stable effective value (RMS value) that does not cause flicker can be obtained.

On the other hand, if the stabilizer of the fluorescent lamp lighting device is an inverter type, the ac current input from the pair of input terminal portions is 20kHz to 100kHz of high frequency, so the PWM control portion does not perform PWM control, and uses the frequency as it is rectified by the rectifier circuit portion (in the case of full-wave rectification, the waveform of the ripple voltage superimposed on the dc current is a frequency 2 times), so that the current flowing through the LED light emitting portion can be controlled by the external inverter type stabilizer (for example, PWM control), and a stable effective value (RMS value) in which flicker is not generated can be obtained.

Therefore, overlapping of the same kind of control methods in the outside and the inside of the LED lamp is reliably prevented, and the cause of the occurrence of an inconsistency such as an unstable magnitude of the current flowing through the LED light-emitting portion is eliminated.

In addition, according to the LED lamp, in addition to the above configuration, a bypass circuit portion is provided between the cathode-side terminal of the LED light emitting portion and the ground-side output terminal of the rectifier circuit portion, the bypass circuit portion includes a switching element and a high-pass filter circuit that outputs a drive voltage of the switching element, and the switching element does not flow a current from the cathode-side terminal of the LED light emitting portion into the ground-side output terminal of the rectifier circuit portion when an alternating current input to the pair of input terminal portions is a frequency lower than a predetermined frequency, and flows a current from the cathode-side terminal of the LED light emitting portion into the ground-side output terminal of the rectifier circuit portion when an alternating current input to the pair of input terminal portions is a frequency higher than the predetermined frequency.

With this configuration, when the ac current input from the input terminal of the rectifier circuit portion is higher than the predetermined frequency, the bypass circuit portion bypasses (bypasses) the switching element of the PWM control portion for PWM-controlling the current flowing through the LED light emitting portion, and the PWM control portion incorporated in the LED lamp can be made not to perform the PWM control.

In addition to the above configuration, according to the LED lamp, the switching element of the bypass circuit portion may be an N-channel MOS FET that controls a flow of current between a drain terminal and a source terminal in accordance with a gate voltage input to a gate terminal, the drain terminal may be connected to a cathode-side terminal of the LED light emitting portion, the source terminal may be connected to a ground-side output terminal of the rectifier circuit portion, the gate terminal may be connected to one of input terminals of the rectifier circuit portion via a high-pass filter circuit, and when an alternating current input to the pair of input terminal portions is higher than a predetermined frequency, a gate voltage driven in such a manner that a current flows from the drain terminal to the source terminal is output to the gate terminal, when the alternating current input to the pair of input terminal sections is lower than a predetermined frequency, a gate voltage driven so as not to cause a current to flow from the drain terminal to the source terminal is output to the gate terminal.

With this configuration, since the N-channel MOS FET functions as a switching element of the bypass circuit, a sufficient amount of current can flow into the LED light emitting unit, and the current can be prevented from flowing into the PWM control unit.

That is, when the ac current supplied from the input terminal of the rectifier circuit unit is higher than the predetermined frequency, the PWM control unit is bypassed (bypassed), so that the current flowing through the LED light emitting unit does not flow into the PWM control unit, and the PWM control unit can be prevented from performing the PWM control.

In addition to the above configuration, the LED lamp may be configured such that the high-pass filter circuit includes a1 st capacitor, a1 st resistor having one terminal connected to one terminal of the 1 st capacitor and connected in series with the 1 st capacitor, a1 st diode connected in a forward direction from the other terminal of the 1 st resistor to the gate terminal, a2 nd capacitor connected between the source terminal and the gate terminal, a2 nd resistor connected between the source terminal and the gate terminal, a zener diode connected in a forward direction from the source terminal to the gate terminal, and a2 nd diode connected in a forward direction from the source terminal to the other terminal of the 1 st resistor, and the other terminal of the 1 st capacitor is connected to one of the input terminals of the rectifier circuit unit.

With this configuration, only the filter function that allows a current having a frequency higher than a predetermined frequency to pass to the next stage is enabled, and the switching element of the bypass circuit can be reliably turned ON/OFF according to the frequency.

As a result, since the current flows into the subsequent stage only when the alternating current supplied from the input terminal of the rectifier circuit portion is higher than the predetermined frequency, the N-channel MOS FET as the switching element can be reliably turned ON, and the current flowing through the LED light emitting portion can be prevented from being PWM-controlled.

In addition, according to the LED lamp, in addition to the above configuration, the predetermined frequency may be a frequency greater than 65Hz and less than 20 kHz.

With this configuration, even when variations in the accuracy of the power supply frequency are taken into consideration, the frequency (60 ± 1 Hz) in the case where the mode of the stabilizer is the glow start type or the rapid start type and the frequency (20 to 100 kHz) in the case of the inverter type distributed in the market can be clearly distinguished, and therefore, the PWM control by the pulse drive and the PWM control by the pulse drive are switched between the case where the PWM control by the pulse drive is performed and the case where the PWM control by the pulse drive is not performed according to the result of the distinction, and the lighting can be performed by the pulse drive at a high frequency.

In particular, the predetermined frequency is set to a frequency within a range of an audible range (frequency band that can be recognized as sound by human beings) of less than 20kHz, and PWM control is performed by pulse driving of a frequency in a frequency band higher than the frequency, so that noise perceived as harsh is also reduced.

The lighting device of the present invention includes an LED lamp having any one of the above configurations.

According to this lighting device, since the LED lamp is included, even if the stabilizer of the fluorescent lamp lighting device is an inverter-type stabilizer of a constant power control type, the magnitude of the current flowing through the LED light emitting portion can be stabilized within a predetermined range only by exchanging the stabilizer with a fluorescent lamp (or the LED lamp) installed from the front.

Further, lighting as illumination can be realized only by supplying an external ac current to the pair of input terminal parts without newly providing a stabilizer for adjusting the light emission of the LED on the side of the illumination device.

Further, since the lighting device itself is not equipped with a stabilizer, the structure of the lighting device is simplified, and it is necessary to select (confirm suitability) a point of the LED lamp depending on the mode of the lighting device, or a point of the lighting device side requiring additional work such as circuit work and direct connection work, and the like.

Further, the present invention provides a current control method for an LED lamp including a pair of input terminal portions, a rectifier circuit portion rectifying an ac current inputted from the outside to the pair of input terminal portions into a dc current, and an LED light emitting portion emitting light by energization of the dc current outputted from the rectifier circuit portion, the method comprising: a stage in which, in a circuit between the pair of input terminal portions and the rectifier circuit portion, an alternating current flows from one of the pair of input terminal portions to the other input terminal portion through the rectifier circuit portion via the variable inductance portion; a step of detecting the magnitude of the DC current flowing into the LED light emitting part in the circuit between the rectifier circuit part and the LED light emitting part; and a step of changing the inductance value of the variable inductance part according to the detected magnitude of the direct current, wherein the magnitude of the direct current flowing into the LED light emitting part is controlled to be within a predetermined range.

According to this method for controlling the current of the LED lamp, even if the ballast of the fluorescent lamp lighting device is a constant power control inverter type ballast, the ballast is exchanged with a fluorescent lamp (or may be an LED lamp) installed in the past, and the inductance value of the variable inductance section is changed in accordance with the magnitude of the current detected by the current detection section, and is fixed so that the output voltage becomes substantially proportional in accordance with the value. As a result, the magnitude of the current flowing through the LED light-emitting portion can be stabilized within a predetermined range.

According to the LED lamp, the lighting device including the LED lamp, and the current control method of the LED lamp of the present invention, even if the stabilizer of the fluorescent lamp lighting device is of the constant power control type inverter type, the magnitude of the current flowing through the LED light emitting portion can be stabilized within a predetermined range by exchanging the stabilizer with a fluorescent lamp (or the LED lamp) mounted in the past.

Drawings

Fig. 1 is a block diagram showing the entire circuit of a lighting device according to an embodiment of the present invention.

Fig. 2 is a circuit diagram of an LED lamp in an embodiment of the present invention.

Fig. 3 is a block diagram illustrating the interior of integrated circuit IC 1.

Fig. 4 is a circuit diagram showing the variable inductance section.

Fig. 5 is a diagram showing a variable control pattern of the variable inductance section.

Fig. 6 is a diagram showing a variable region and a circuit breaking region for the inductance value of the detection current.

Fig. 7 is a flowchart illustrating a current control method of an LED lamp in an embodiment of the present invention.

Fig. 8 (a) and (b) are an input voltage waveform at an inductance value of 100 μ H of the LED lamp and a current waveform flowing through the LED light emitting portion when the LED lamp is turned on by the constant power control inverter stabilizer, respectively, and fig. 8 (c) and (d) are an input voltage waveform at an inductance value of 400 μ H of the LED lamp and a current waveform flowing through the LED light emitting portion when the LED lamp is turned on by the constant power control inverter stabilizer, respectively.

Fig. 9 (a) and (b) are an input voltage waveform at an inductance value of 100 μ H of the LED lamp and a current waveform flowing through the LED light emitting portion when the LED lamp is turned on by the constant power control inverter stabilizer, respectively, and fig. 9 (c) and (d) are an input voltage waveform at an inductance value of 400 μ H of the LED lamp and a current waveform flowing through the LED light emitting portion when the LED lamp is turned on by the constant power control inverter stabilizer, respectively.

Fig. 10 (a) is a waveform of the input voltage Vin, fig. 10 (b) is a waveform of a voltage Vg1 of the gate terminal of the switching element Q1, fig. 10 (c) is a waveform of a current sensor terminal voltage Vcs of the integrated circuit IC1, fig. 10 (d) is a waveform of a voltage Vg2 of the gate terminal of the switching element Q2, and fig. 10 (e) is a waveform of a current i flowing through the LED light emitting unit 24.

Fig. 11 (a) is a waveform of the input voltage Vin, fig. 11 (b) is a waveform of a voltage Vg1 of the gate terminal of the switching element Q1, fig. 11 (c) is a waveform of a voltage Vcs of the current sensor terminal of the integrated circuit IC1, fig. 11 (d) is a waveform of a voltage Vg2 of the gate terminal of the switching element Q2, and fig. 11 (e) is a waveform of a current i flowing through the LED light emitting unit 24.

Fig. 12 (a) is a waveform of the input voltage Vin, fig. 12 (b) is a waveform of a voltage Vg1 of the gate terminal of the switching element Q1, fig. 12 (c) is a waveform of a voltage Vcs of the current sensor terminal of the integrated circuit IC1, fig. 12 (d) is a waveform of a voltage Vg2 of the gate terminal of the switching element Q2, and fig. 12 (e) is a waveform of a current i flowing through the LED light emitting unit 24.

Fig. 13 is a block diagram showing the entire circuit of the lighting device according to the modification of the present invention.

Fig. 14 (a) is a diagram of a part of a circuit for varying the threshold voltage in accordance with the magnitude of the High Voltage (HV), and fig. 14 (b) is an overall configuration diagram in which the LED lamp in the present embodiment is connected in series to a series regulator.

Fig. 15 (a) is a diagram showing an example of a glow starter type ballast, fig. 15 (b) is a diagram showing an example of a rapid start type ballast, and fig. 15 (c) is a diagram showing an example of an inverter type ballast.

Fig. 16 is a diagram showing an example of the series type fast stabilizer.

(symbol description)

10. 100, and (2) a step of: an illumination device; 11: a plug; 12: a stabilizer; 20. 50, 60, 200: an LED lamp; 20a, 20b, 20c, 20 d: an input terminal section; 21: a protection circuit unit; 22: a rectifier circuit section; 23: smoothingA circuit section; 24: an LED light emitting section; 25: a PWM control unit; 26: a bypass circuit section; 31: a current detection unit; r31: a resistance; c31: a capacitor; 32: an inductance variable control section; 33: a circuit cutting part; 34: a threshold element; d34a, D34 b: a Zener diode; RY 34: a relay; l50, L60: a variable inductance section; l51, L52, L61, L62: an inductor; 32a, 32b, 32 c: a switching element; c1, C2, C9, C10, C11, C12, C20: a capacitor; c3, C4, C5: an electrolytic capacitor; c6: a1 st capacitor; c7: a2 nd capacitor; d2, D3, D4, D5, D6, D7: a diode; d8: a2 nd diode; d9: a1 st diode; d1, D10, D20: a Zener diode; z9, Z10, Z11, Z12: an input circuit section; HV: a high voltage; f1: a fuse; IC 1: an integrated circuit; l1, L2, L3, L4: a choke coil; q1, Q2: a switching element; r1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R20, R21, R22: a resistance; r13: a1 st resistor; r14: a2 nd resistor; RT: a resistance value; SA 1: a 2-pole discharge tube; SA 2: a variable resistor; s01, S02, S03, S04: a step of; t1, T2, T3, T4, T6, T8, T9, T11, T12: a terminal; t5: a ground side output terminal; t7: a High Voltage (HV) side output terminal; TA: an anode-side terminal; TK: a cathode-side terminal; TG: a GND terminal; vin: inputting a voltage; vcs: a current sensor terminal voltage; vg 1: the voltage of the gate terminal of the switching element Q1; vg 2: the voltage of the gate terminal of the switching element Q2; i: current flowing in the LED light emitting portion; t is t_OSC: an oscillation period; t1, t 2: and (4) period.

Detailed Description

Hereinafter, specific embodiments will be described with reference to the drawings.

(embodiment mode)

Fig. 1 is a block diagram showing the entire circuit of an illumination device in an embodiment of the present invention, fig. 2 is a circuit diagram of an LED lamp in an embodiment of the present invention, fig. 3 is a block diagram showing the inside of an integrated circuit IC1, fig. 4 is a circuit diagram showing a variable inductance part, fig. 5 is a diagram showing a variable control mode of the variable inductance part, fig. 6 is a diagram showing a variable region and a circuit interruption region for an inductance value of a detection current, fig. 7 is a flowchart showing a current control method of the LED lamp in an embodiment of the present invention, fig. 8 (a) to (d) and fig. 9 (a) to (d) are input voltage waveforms of the LED lamp and current waveforms flowing in an LED light emitting part when the LED lamp in an embodiment of the present invention is turned on by a constant power control inverter-type stabilizer, and fig. 10 (a) to (e) are voltage waveforms at respective measurement points when a glow-type is used as a stabilizer of the illumination device in an embodiment of the present invention Fig. 11 (a) to (e) are voltage waveform diagrams at each measurement point in the case where the rapid start type is used as the stabilizer of the lighting device in the embodiment of the present invention, fig. 12 (a) to (e) are voltage waveform diagrams at each measurement point in the case where the inverter type is used as the stabilizer of the lighting device in the embodiment of the present invention, fig. 13 is a block diagram showing the whole circuit of the lighting device in the modification example of the present invention, fig. 14 (a) is a diagram showing a part of the circuit in which the threshold voltage is changed in accordance with the magnitude of the High Voltage (HV), and fig. 14 (b) is a whole configuration diagram in which the LED lamp in the embodiment is connected in series to the rapid series stabilizer.

First, as shown in fig. 1, the lighting device 10 according to the embodiment of the present invention includes a plug 11 connected to supply power from an external power supply having an AC voltage of 100 to 240V (50 Hz/60 Hz) for home use, for example, a stabilizer 12 for controlling the power input from the plug 11 to light a fluorescent lamp, and an LED lamp 20 for inputting a predetermined voltage between a pair of input terminal portions (between an input terminal portion 20a and an input terminal portion 20 c) in accordance with the mode of the stabilizer 12.

Here, the ballast 12 may be any one of a well-known glow start type, quick start type, or inverter type for lighting an existing fluorescent lamp.

Further, if the external power supply connected to the plug 11 is AC voltage 100 to 240V (50 Hz/60 Hz), the LED lamp 20 normally operates, so that the external power may be directly input to the LED lamp 20 without passing through the stabilizer 12.

Here, the line from which the ac current is output from the stabilizer 12 is connected so as to be able to be input to either one or both of a pair of input terminal portions (between the input terminal portion 20a and the input terminal portion 20 c) or a pair of input terminal portions (between the input terminal portion 20b and the input terminal portion 20 d).

On the other hand, an input circuit unit Z9 (see fig. 2) including an RC parallel circuit of a resistor R9 and a capacitor C9 is connected between the input terminal portion 20a of the LED lamp 20 and the terminal T1.

Similarly, an input circuit unit Z10 (see fig. 2) including an RC parallel circuit of a resistor R10 and a capacitor C10 is connected between the input terminal unit 20b of the LED lamp 20 and the terminal T1.

Similarly, an input circuit unit Z11 (see fig. 2) including an RC parallel circuit of a resistor R11 and a capacitor C11 is connected between the input terminal unit 20C of the LED lamp 20 and the terminal T2.

Similarly, an input circuit unit Z12 (see fig. 2) including an RC parallel circuit of a resistor R12 and a capacitor C12 is connected between the input terminal unit 20d of the LED lamp 20 and the terminal T2.

Accordingly, the resistance values of the resistor R9 and the resistor R10 between the input terminal portions 20a and 20b are selected to be about several Ω to about 100 Ω so as to correspond to the resistance component of the filament of the fluorescent lamp.

Similarly, the resistance values of the resistor R11 and the resistor R12 between the input terminal portion 20c and the input terminal portion 20d are selected to be about several Ω to about 100 Ω, respectively, so as to correspond to the resistance component of the filament of the fluorescent lamp.

If the resistances of the resistors R9 to R12 are selected as described above, even if the ballast 12 is of the inverter type, and the type in which it is automatically detected whether or not a fluorescent lamp is mounted on the load side (whether or not conduction is performed by the filament resistor), and power is not output in the case where no fluorescent lamp is mounted (whether or not conduction is performed by the filament resistor), the resistors R9 to R12 function as dummy resistors, and thus power is normally supplied to the LED lamp 20.

Further, the circuit breaker 33 is connected between the terminal T1 and the terminal T11, and similarly, the circuit breaker 33 is connected between the terminal T2 and the terminal T12. The circuit interrupting unit 33 includes, for example, a B-contact type relay, and can interrupt an ac current from the pair of input terminal units when the magnitude of the current i flowing through the LED light emitting unit 24 is abnormal. The circuit breaker 33 will be described in detail later.

Further, the protection circuit portion 21 (see fig. 2) is inserted between the terminals T11 and T12.

The protection circuit unit 21 is obtained by connecting a 2-pole discharge tube SA1 filled with an inert gas such as neon or argon and a variable resistor SA2 in series.

By appropriately setting the discharge start voltage of the 2-pole discharge tube SA1 and the limit voltage of the variable resistor SA2, the surge voltage between the terminal T1 and the terminal T2 from the power supply side can be suppressed to, for example, a peak value of about 400V or less. In addition, by combining 2-pole discharge tube SA1 and variable resistor SA2 in series, a follow current (follow current) due to the continued discharge of 2-pole discharge tube SA1 after the surge voltage has subsided can be effectively prevented by variable resistor SA 2.

Thus, even if a lightning surge or an induced lightning surge intrudes from the external input power supply side, for example, the surge current is absorbed and the surge current is prevented from flowing into the rectifier circuit unit 22 side.

Therefore, the electronic components such as the rectifier circuit unit 22 and the diode and the capacitor constituting the LED light emitting unit 24 can be protected.

Further, the threshold element 34 is connected in series to the terminal T12. The threshold value element 34 includes, for example, 2 zener diodes D34a, D34b connected in series in reverse (bi-directional) to each other, and a relay RY34 connected in parallel to these zener diodes (refer to fig. 2). The relay RY34 is driven by an output voltage from a delay circuit (not shown) that outputs a predetermined voltage after a predetermined time has elapsed since the current has flowed into the LED light emitting unit 24, and short-circuits both ends of the 2 zener diodes D34a and D34 b. The delay circuit is set to output a predetermined voltage and drive the relay RY34 after a predetermined time elapses since the ac current exceeds a predetermined threshold value of the threshold value element 34 and starts flowing into the rectifier circuit portion 22 at the subsequent stage. Thus, in the threshold element 34, after a predetermined time has elapsed since the ac current exceeding the predetermined threshold value is inputted from the outside to the pair of input terminal units, both ends thereof are short-circuited by the relay RY 34. The threshold element is defined as an element that starts conduction of electricity inside the element if a voltage equal to or higher than a predetermined threshold value is applied between two terminals, and a bidirectional switching element (registered trademark) such as a gateless 2-terminal type thyristor, a diode discharge tube, or the like can be applied as the threshold element 34 instead of the zener diodes D34a and D34 b. The threshold value element 34 will be described in detail later.

Further, a variable inductance unit L50 is inserted between the terminal T11 and the terminal T3 on one input side of the rectifier circuit unit 22, and similarly, a variable inductance unit L60 is connected in series with the threshold element 34 between the terminal T12 and the terminal T6 on the other input side of the rectifier circuit unit 22. Inductance values (hereinafter, also referred to as L values) of the variable inductance sections L50 and L60 are controlled by the variable inductance control section 32. The inductance of the variable inductance sections L50 and L60 is variable as described in detail later.

Thus, the variable inductor L50 and the variable inductor L60 function as impedances that limit currents flowing in response to high-frequency pulses.

Therefore, for example, when the ballast 12 is of a glow start type or a rapid start type, the switching element Q1 performs an ON/OFF operation, and thus the switching noise (high-frequency noise pulse) can be prevented from flowing out to the external ac current side (input power supply) through any of the input terminal sections 20a to 20 d.

In addition, since the ac current of 20kHz to 100kHz at a high frequency is input when the stabilizer 12 is of the inverter type, the variable inductor L50 and the variable inductor L60 function as loads that do not cause active power loss (reactive power loss).

Accordingly, when the load impedance of the LED lamp 20 is within a predetermined range, the inverter-type stabilizer 12 stably outputs power, as viewed from either or both of the pair of input terminal portions (between the input terminal portion 20a and the input terminal portion 20 c) and the pair of input terminal portions (between the input terminal portion 20b and the input terminal portion 20 d).

The rectifier circuit unit 22 includes a bridge diode including 4 diodes D4 to D7, and an electrolytic capacitor C4 and an electrolytic capacitor C5 (see fig. 2) connected in parallel to smooth the full-wave rectified waveform in the output stage.

Further, the output-side terminal of the rectifier circuit unit 22 outputs a dc voltage between the high-voltage (HV) output terminal T7 and the ground output terminal T5.

The High Voltage (HV) side output terminal T7 is connected to the anode side terminal TA of the LED light emitting unit 24 via the smoothing circuit unit 23, and the cathode side terminal TK of the LED light emitting unit 24 is connected to the PWM control unit 25 via the smoothing circuit unit 23.

Here, the LED light emitting unit 24 is configured by a circuit in which 30 LEDs (light emitting diodes) having a forward voltage of about 3V are connected in series and a 3-circuit parallel connection is provided, and a current i flows in a direction (direction of an arrow) from the anode side terminal TA to the cathode side terminal TK.

Further, the GND terminal TG of the PWM control unit 25 is connected to the ground-side output terminal T5 on the output side of the rectifier circuit unit 22.

With the above circuit configuration, the current i flowing through the LED light emitting unit 24 is controlled within a predetermined current value range by PWM control unit 25 performing PWM control by pulse driving at a frequency higher than a predetermined frequency.

On the other hand, the bypass circuit unit 26 is connected between the cathode-side terminal TK of the LED light emitting unit 24 and the ground-side output terminal T5 of the rectifier circuit unit 22.

Thus, when the frequency of the alternating current input to one terminal T3 of the rectifier circuit unit 22 is higher than a predetermined frequency, even if the switching element Q1 is in the ON state (the state in which the current flows from the drain terminal to the source terminal, the same applies hereinafter), the resistor R3, the resistor R4, and the resistor R5 are connected in parallel between the terminal T9 and the terminal TG, so the PWM control unit 25 is bypassed (bypassed), and the current i flowing through the LED light emitting unit 24 flows directly from the cathode-side terminal TK to the ground-side output terminal T5 of the rectifier circuit unit 22 via the GND terminal TG of the PWM control unit 25.

Therefore, the current i hardly flows into the PWM control section 25, and therefore the current i is not PWM-controlled.

In the above and following descriptions, PWM control of the current i according to the duty ratio (PWM is short for PULSE WIDTH MODULATION, and is the same hereinafter) is defined such that the period of the drive PULSE is constant, and the current i is ON/OFF controlled according to the duty ratio of the drive PULSE (which is the ratio of the PULSE WIDTH to the PULSE period and is the same as the power factor, and is the same hereinafter) according to the magnitude of the input signal (in the case of the present embodiment, the magnitude of the voltage detected in the #2 tube serving as the current sensor terminal), and such that the duty ratio at this time is greater than 0% and less than 100%.

This stabilizes the magnitude of the current i flowing through the LED light emitting unit 24.

ON the other hand, the definition of not performing the PWM control ON the current i according to the duty ratio is that the PWM control unit does not perform the ON/OFF control ON the current i according to the duty ratio, and includes, as described above, a case where the duty ratio of the drive pulse is 0% and the switching element Q1 is always in the FF state during the operation, and a case where the duty ratio of the drive pulse is 100% and the switching element Q1 is always in the ON state during the operation, in addition to a case where the current i hardly flows into the PWM control unit.

The current detection unit 31 is connected in series with the bypass circuit unit 26 between the cathode-side terminal TK of the LED light emitting unit 24 and the ground-side output terminal T5 of the rectifier circuit unit 22. When the current i flowing through the LED light emitting unit 24 is bypassed by the bypass circuit unit 26 (when the stabilizer is of the inverter type), the current detection unit 31 detects the magnitude of the dc current and outputs a detection signal (dc voltage) thereof to the inductance variable control unit 32.

Then, the inductance variable control unit 32 controls the inductance values of the variable inductance units L50 and L60 in accordance with the magnitude of the current detected by the current detection unit 31. The inductance variable control unit 32 will be described in detail later.

Next, each component will be described in further detail with reference to fig. 2 to 6.

As described above, the resistor R9 between the input terminal portion 20a and the terminal T1 functions as a dummy resistor corresponding to the filament of the fluorescent lamp, but the capacitor C9 can pass an alternating current in a normal operating state (during lighting of the LED light emitting unit 24).

This allows the current to be shunted in inverse proportion to the ratio of the capacitance reactance determined by the frequency of the alternating current and the capacitance of the capacitor C9 to the resistance value of the resistor R9, and therefore, the heat generation of the resistor R9 is suppressed accordingly.

Similarly, although the resistor R11 between the input terminal portion 20C and the terminal T2 functions as a dummy resistor corresponding to the filament, the capacitor C11 allows an alternating current to pass therethrough in a normal operating state, and thus suppresses heat generation of the resistor R11.

The fuse F1 is used for overcurrent protection of a power supply current input to either one or both of a pair of input terminal portions (between the input terminal portion 20a and the input terminal portion 20 c) and a pair of input terminal portions (between the input terminal portion 20b and the input terminal portion 20 d).

Next, the rectifier circuit unit 22 includes, at the previous stage, a bridge diode including a diode D4 having an anode connected to the terminal T3 and a cathode connected to the high-voltage (HV) side output terminal T7, a diode D5 having an anode connected to the terminal T6 and a cathode connected to the high-voltage (HV) side output terminal T7, a diode D6 having an anode connected to the ground side output terminal T5 and a cathode connected to the terminal T4 having the same potential as that of the terminal T3, and a diode D7 having an anode connected to the ground side output terminal T5 and a cathode connected to the terminal T6.

In the subsequent stage of the bridge diode, in order to smooth the full-wave rectified waveform, between the High Voltage (HV) side output terminal T7 and the ground side output terminal T5, the electrolytic capacitor C4 and the electrolytic capacitor C5 are connected in parallel such that the High Voltage (HV) side output terminal T7 is positive (+), and the ground side output terminal T5 is negative (-) terminal.

Thus, the smoothed and rectified output voltage is output to the High Voltage (HV) side output terminal T7, and the low voltage side is output to the ground side output terminal T5.

Then, the smoothing circuit unit 23 removes a pulsating component (ripple component) from the high-voltage dc voltage output to the high-voltage (HV) side output terminal T7, and is called a so-called choke coil input smoothing circuit, and the LED light emitting unit 24 is configured by a parallel circuit of a series circuit of choke coils L1 to L4 and an electrolytic capacitor C3.

Further, the smoothing circuit unit 23 functions to cause a current i from which a pulsating component is removed to flow from the anode-side terminal TA of the LED light emitting unit 24 to the cathode-side terminal TK, thereby causing 90 LEDs (light emitting diodes) in total constituting the LED light emitting unit 24 to emit light.

Further, the current i passing through the smoothing circuit 23 from the LED light emitting unit 24 passes through the integrated circuit IC1 constituting the PWM control unit 25, and the resistors R1 to R8, the capacitor C1, the capacitor C2, the zener diode D1, the diode D2, and the switching element Q1 connected to the pins (# 1 to # 8), and utilizes a predetermined oscillation period t_OSC(μ s) of the pulse-shaped driving,and performing PWM control.

For example, when a commercially available version HV9910B (see fig. 3) manufactured by supertex (r) is used as the integrated circuit IC1, the oscillation period t is set to be equal to the oscillation period t_OSC(μ s) resistance value R of resistor R1 connected to pin #8_T(k Ω) is controlled by the time obtained by the following equation 1.

[ formula 1 ]

In the present embodiment, for example, if the resistance R1 is set to about 499 (k Ω), the oscillation period t is set to be the oscillation period t_OSC(. mu.s), about 20.84 (. mu.s) was determined by the above equation 1.

Therefore, if the oscillation period is assumed to be about 20.84 (μ s) in accordance with the calculated value, the pulse driving at a high frequency of about 48kHz can be performed.

The switching element Q1 for ON/OFF-controlling the current i flowing through the LED light emitting unit 24 is an N-channel MOS FET capable of controlling the flow of current between the drain terminal and the source terminal in accordance with the input voltage to the gate terminal.

Here, in the integrated circuit IC1, the drain terminal of the switching element Q1 is connected to the anode terminal of the diode D3 constituting a part of the smoothing circuit unit 23, the terminal T9 connected to the #2 pin as the current sensor terminal of the integrated circuit IC1 via the resistor R6 is connected to the source terminal, and the voltage obtained by dividing the voltage output from the #4 pin of the integrated circuit IC1 by the resistor R2 and the resistor R7 and the voltage corresponding to the resistor R7 are input to the gate terminal.

Further, since the #1 pin of the integrated circuit IC1 is connected to the High Voltage (HV) side output terminal T7 via the resistor R8 and the zener diode D1, the dc high voltage output from the rectifier circuit unit 22 is supplied to the #1 pin.

As a result, the voltage supplied from the pin #1 (about DC8V to about DC 450V) is reduced to a predetermined VDD voltage (about DC 12V) by an internal regulator, rectified and stabilized, and functions as a driving power source for the internal circuit of the integrated circuit IC1, and the VDD voltage is output to the pin #6 (see fig. 3).

By the above-described connection, by the pulse driving of the integrated circuit IC1, if the voltage detected at the #2 pin as the current sensor terminal does not exceed about DC250mV of the threshold voltage, a high-level (about DC7.5V) voltage is output to the gate terminal of the switching element Q1 to turn ON, and if the voltage detected at the #2 pin as the current sensor terminal reaches about DC250mV of the threshold voltage, a low-level (about 0V) voltage is output to the gate terminal of the switching element Q1 to turn OFF (a state in which a current does not flow from the drain terminal to the source terminal, which will be the same hereinafter).

As described above, the current i flowing through the LED light-emitting unit is controlled by the period of the drive pulse of the voltage Vg1 at the gate terminal of the output switch element Q1 by the operation of the integrated circuit IC1 being constant, and the duty ratio of the pulse width of the voltage Vg1 at the gate terminal being variable in accordance with the level of the voltage (current sensor terminal voltage Vcs) detected at the #2 pin.

That is, since the current i is PWM-controlled by the high-frequency pulse driving of the PWM control unit 25, the ON/OFF of the switching element Q1 is repeated with the oscillation period t obtained by the above equation 1_OSC(μ s) and the number of pulses (triangular wave) is repeatedly increased and decreased.

In the present embodiment, since the #7 pin is connected to (shared with) the #6 pin, a voltage VDD (about DC 12V) exceeding the threshold voltage (about DC250 mV) is input to the #7 pin.

In the present embodiment, the threshold voltage to be compared with the voltage detected at the #2 pin that is the current sensor terminal is set to about DC250mV (see fig. 3) generated inside the integrated circuit IC 1.

On the other hand, if a voltage in a range not exceeding about DC250mV is set as the voltage input to pin #7 of the integrated circuit IC1, the voltage can be set as a threshold voltage to be compared with the voltage detected at the current sensor terminal (# 2 pin), and therefore, the duty ratio can be further reduced.

This can reduce the effective value (RMS value) of the current i flowing through the LED light emitting unit 24, thereby enabling dimming (light reduction).

Here, if the switching element Q1 is turned OFF, in the series circuit of the choke coils L1 to L4, a diode D3 for absorbing a current due to an excitation current i is connected so that a counter electromotive force in a direction in which the excitation current i flows is directed forward from the terminal T8 of the terminal of the choke coil L1 toward the anode-side terminal TA of the LED light emitting unit 24.

On the other hand, as described above, the bypass circuit portion 26 and the current detection portion 31 are provided between the cathode-side terminal TK of the LED light emitting portion 24 and the ground-side output terminal T5 of the rectifier circuit portion 22.

The bypass circuit unit 26 includes a switching element Q2 and a high-pass filter circuit that outputs a drive voltage (gate terminal voltage) to the switching element Q2.

Here, the switching element Q2 of the bypass circuit unit 26 is an N-channel MOS FET that controls the flow of current between a drain terminal and a source terminal in accordance with a voltage input to a gate terminal, the drain terminal is connected to the cathode-side terminal TK of the LED light emitting unit 24, the source terminal is (electrically) connected to the ground-side output terminal T5 of the rectifier circuit unit 22 via the current detection unit 31, and the gate terminal is connected to the terminal T4 of the rectifier circuit unit 22 via the high-pass filter circuit.

The high-pass filter circuit includes a1 st capacitor C6, a1 st resistor R13 having one terminal connected to one terminal of the 1 st capacitor C6 and connected in series with the 1 st capacitor, a1 st diode D9 connected in a forward direction from the other terminal of the 1 st resistor R13 to the gate terminal of the switching element Q2, a2 nd capacitor C7 electrically connected between the source terminal and the gate terminal of the switching element Q2, a2 nd resistor R14 electrically connected between the source terminal and the gate terminal, a zener diode D10 connected in a forward direction from the source terminal to the gate terminal, and a2 nd diode D8 electrically connected in a forward direction from the source terminal to the other terminal of the 1 st resistor R13.

The other terminal of the 1 st capacitor C6 is connected to one of the input terminals (the terminal T3 or the terminal T6 via the terminal T4) of the rectifier circuit unit 22.

In this high-pass filter circuit, if the circuit constants of the 1 st capacitor C6, the 1 st resistor R13, and the 2 nd resistor R14 are selected so as to block (cut off) a portion of the ac current input to the terminal T3 that is equal to or lower than a predetermined frequency, the CR circuit including the capacitors and the resistors functions as a high-pass filter, and therefore only the ac current having a frequency exceeding the predetermined frequency is passed to the subsequent stage.

That is, a dc voltage is generated ON the high voltage side of the 2 nd capacitor C7, the 2 nd resistor R14, and the zener diode D10 by an ac current having a frequency higher than the predetermined frequency input to the terminal T3, and a voltage capable of turning the switching element Q2 ON is output to the gate terminal.

The voltage of the gate terminal may be set as appropriate according to the voltage division ratio between the 1 st resistor R13 and the 2 nd resistor R14 and the zener voltage of the zener diode D10 that limits the voltage input to the gate terminal, and may be set to a high-level voltage range of the gate terminal that can turn the switching element Q2 to an ON state.

In addition, since the high-pass filter circuit is an input circuit for a filter for passing an alternating current and setting the gate terminal of the switching element Q2 to a high level (for example, approximately DC 14V) when the frequency of the alternating current is higher than a predetermined frequency, the high-pass filter circuit may be connected to the terminal T6 to which the same alternating current (only 180 degrees out of phase) is input to the ground-side output terminal T5 of the rectifier circuit unit 22.

With the above configuration, the high-pass filter circuit outputs a predetermined gate voltage for causing a current to flow from the drain terminal to the source terminal when the alternating current input to the input terminal of the rectifying circuit section 22 is higher than a predetermined frequency (in the present embodiment, the capacitance of the 1 st capacitor C6 is selected to be 100pF, the resistance value of the 1 st resistor R13 is selected to be 51k Ω, the resistance value of the 2 nd resistor R14 is selected to be 51k Ω, and the cutoff frequency is set to about 5kHz by actual measurement, which is the same hereinafter), and outputs a gate voltage for preventing a current from flowing from the drain terminal to the source terminal when the alternating current is lower than the predetermined frequency.

That is, the switching element Q2 is capable of causing no current to flow from the cathode-side terminal TK of the LED light emitting unit 24 to the ground-side output terminal T5 of the rectifier circuit unit 22 via the GND terminal TG of the PWM control unit 25 when the ac current input from the input terminal of the rectifier circuit unit 22 is at a frequency lower than a predetermined frequency (about 5 kHz), and causing a current to flow from the cathode-side terminal TK of the LED light emitting unit 24 to the ground-side output terminal T5 of the rectifier circuit unit 22 via the GND terminal TG of the PWM control unit 25 when the ac current input from the input terminal of the rectifier circuit unit 22 is at a frequency higher than a predetermined frequency (hereinafter, referred to as an off frequency and set to about 5 kHz).

As a result, when the frequency of the external ac current input to the pair of input terminal portions is lower than a predetermined frequency (for example, when the current is input from a glow starter or a rapid start ballast), the PWM control unit 25 performs PWM control on the current i flowing through the LED light emitting unit 24 by pulse driving at a frequency higher than the predetermined frequency, and the current i becomes a pulse wave (triangular wave).

On the other hand, when the frequency of the external ac current input to the pair of input terminal units is higher than a predetermined frequency (for example, when the ac current is input from an inverter-type stabilizer), the PWM control unit 25 bypasses the bypass circuit unit 26, and therefore the current i flowing through the LED light emitting unit 24 flows directly to the ground side output terminal T5 of the rectifier circuit unit 22 without being PWM controlled by the PWM control unit 25.

Therefore, since the high-frequency ac current input to the pair of input terminal portions passes through only the rectifier circuit portion 22, the smoothing circuit portion 23, and the LED light emitting portion 24, the current i flowing through the LED light emitting portion 24 has a waveform that is rectified and direct-converted by full-wave rectification with respect to the ac current input to the pair of input terminal portions (see, for example, fig. 12 (e)).

The current detection unit 31 is formed of an RC parallel circuit including a resistor R31 and a capacitor C31. When the switching element Q2 in the bypass circuit unit 26 is turned ON, the current detection unit 31 detects the magnitude of the current flowing from the drain terminal to the source terminal of the switching element Q2. That is, the current detection unit 31 detects the current i flowing through the LED light emitting unit 24 when the frequency of the external ac current input to the pair of input terminal units is higher than a predetermined frequency, for example, when the stabilizer is an inverter type. In the present embodiment, the current detection unit 31 outputs a detection signal (dc voltage) corresponding to the value of the current flowing in itself to the inductance variable control unit 32.

The inductance variable control unit 32 includes a microprocessor, and controls the inductance values of the variable inductance units L50 and L60 in accordance with the magnitude of the current detected by the current detection unit 31 (i.e., in accordance with the magnitude of the dc voltage from the current detection unit 31).

For example, as shown in fig. 4 (a), the variable inductance section L50 includes an inductor L51 and an inductor L52 connected in series, and switching elements 32a and 32b connected in parallel to the inductors L51 and L52, respectively. On the other hand, as shown in fig. 4 (b), the variable inductance section L60 includes an inductor L51 and an inductor L52 connected in series, and a switching element 32c connected in parallel to both ends of the series circuit of the inductors L51 and L52. In addition, for example, a sliding inductor, a magnetic amplifier, or the like may be applied to the variable inductance units L50 and L60.

The inductance variable controller 32 can vary the total inductance of the variable inductance sections L50 and L60 by ON/OFF controlling the switching elements 32a, 32b, and 32 c. For example, as shown in fig. 5 and 6, when the magnitude of the current i flowing through the LED light emitting unit 24 is within a predetermined range (L value non-variable region), the variable inductance controller 32 sets the inductance values of the variable inductance units L50 and L60 to the total inductance value of the inductors L52, L61, and L62 by turning the switching element 32a to the ON state and turning the switching elements 32b and 32c to the OFF state as in the mode 2.

ON the other hand, when the magnitude of the current i flowing through the LED light emitting unit 24 is smaller than the predetermined range (when the current i is within the L value variable (falling) region), the total inductance value of the variable inductance units L50 and L60 is changed to a small value by turning all the switching elements 32a to 32c ON as in mode 3. As a result, the output voltage of the constant power control inverter-type stabilizer decreases and the output current increases. That is, since the current i flowing through the LED light emitting unit 24 can be increased, the magnitude of the current i flowing through the LED light emitting unit 24 can be stabilized within a predetermined range.

In the case where the magnitude of the current i flowing through the LED light emitting unit 24 is larger than the predetermined range (in the case where the current i is within the L value variable (rising) region), the total inductance value of the variable inductance units L50 and L60 is largely changed by turning OFF all the switching elements 32a to 32c as in mode 1. As a result, the output voltage of the constant power control inverter-type stabilizer increases and the output current decreases. That is, since the current i flowing through the LED light emitting unit 24 can be reduced, the magnitude of the current i flowing through the LED light emitting unit 24 can be stabilized within a predetermined range.

On the other hand, when the magnitude of the current detected by the current detection unit 31 exceeds a predetermined upper limit value (when the current is within the circuit interruption region), the inductance variable control unit 32 controls the circuit interruption unit 33 to interrupt the ac current flowing from the pair of input terminal units to the rectifier circuit unit 22 (overcurrent protection). When the magnitude of the current detected by the current detection unit 31 is lower than a predetermined lower limit value (when the current is within the circuit interruption region), the inductance-variable control unit 32 controls the circuit interruption unit 33 to interrupt the ac current flowing from the pair of input terminal units to the rectifier circuit unit 22 (some kind of current abnormality protection).

In the present embodiment, the current detection unit 31 detects the current after both ends of the threshold element 34 are short-circuited. For example, according to the type of the constant power control type inverter-type stabilizer, at the start of output, in order to grasp the state of a fluorescent lamp (for example, check whether or not the fluorescent lamp is mounted on the load side), the output voltage is set to a small amount of current lower than the rated value and an appropriate amount of light is not obtained, the magnitude of the output current at that time is monitored, and then the output voltage is increased to a predetermined range, and then the constant power control is performed. However, in the present embodiment, after a predetermined time has elapsed since an ac current exceeding a predetermined threshold value is inputted to the pair of input terminal portions from the outside, both ends of the threshold value element 34 are short-circuited, and the inductance value of the variable inductance portion is variable according to the magnitude of the dc current flowing through the LED light emitting portion in which both ends of the threshold value element 34 are short-circuited, so that even in the inverter-type stabilizer of this type, it is possible to detect only the current (current in a normal lighting state) flowing through the LED light emitting portion to be detected, thereby preventing erroneous control.

Next, a current control method of the LED lamp in the case where the stabilizer is an inverter type of the constant power control type will be described with reference to fig. 7.

First, as the initial setting, the inductance values of the variable inductance sections L50 and L60 are set to the mode 2 by the inductance variable control section 32 (step S01).

Next, if a predetermined time elapses after the ac current exceeding the predetermined threshold value is input from the constant power control type inverter-type stabilizer to the pair of input terminal sections, both ends of the threshold value element 34 are short-circuited, and the ac current that can be normally lit flows into the variable inductance sections L50, L60 and the rectifier circuit section 22. Then, since the stabilizer is an inverter type and the frequency of the alternating current is higher than a predetermined frequency, the switching element Q2 in the bypass circuit unit 26 is turned ON, and the current flowing into the rectifier circuit unit 22 through the variable inductor units L50 and L60 and rectified by the rectifier circuit unit 22 is supplied to the LED light emitting unit 24 (step S02). At this time, the current i flowing through the LED light emitting unit 24 is not PWM-controlled by the PWM control unit 25 and is not smoothed (bypassed) by the smoothing circuit unit 23.

Next, the current detection unit 31 detects the magnitude of the current i flowing through the LED light emitting unit 24 (step S03). When the magnitude of the current detected by the current detector 31 is within the predetermined range (L value non-variable region shown in fig. 6), the inductance variable controller 32 keeps the inductance values of the variable inductance sections L50 and L60 unchanged in the mode 2 (step S04).

However, when the magnitude of the current detected by the current detection unit 31 is smaller than the predetermined range (in the case of the L value variable (falling) region shown in fig. 6), the inductance values of the variable inductance units L50 and L60 are set to the pattern 3 by the inductance variable control unit 32, and the total inductance value is changed to a small extent. As a result, the output voltage of the constant power control inverter-type stabilizer decreases and the output current increases. That is, since the current i flowing through the LED light emitting unit 24 can be increased, the magnitude of the current i flowing through the LED light emitting unit 24 is stabilized within a predetermined range (step S04).

On the other hand, when the magnitude of the current detected by the current detection unit 31 is larger than the predetermined range (in the case of the L value variable (rising) region shown in fig. 6), the inductance values of the variable inductance units L50 and L60 are set to the mode 1 by the inductance variable control unit 32, and the total inductance value is greatly variable. As a result, the output voltage of the constant power control inverter-type stabilizer increases and the output current decreases. That is, since the current i flowing through the LED light emitting unit 24 can be reduced, the magnitude of the current i flowing through the LED light emitting unit 24 is stabilized within a predetermined range (step S04).

In the case where the magnitude of the current detected by the current detection unit 31 exceeds the predetermined upper limit value (in the case of the circuit breaking region shown in fig. 6), the inductance-variable control unit 32 controls the circuit breaking unit 33 to break the ac current flowing from the pair of input terminal units to the rectifier circuit unit 22 (overcurrent protection). In the case where the magnitude of the current detected by the current detection unit 31 is lower than the predetermined lower limit value (in the case of the circuit interrupting region shown in fig. 6), the inductance-variable control unit 32 controls the circuit interrupting unit 33 to interrupt the ac current flowing from the pair of input terminal units into the rectifier circuit unit 22 (some kind of current abnormality protection).

Next, referring to fig. 8 and 9, the observed waveforms of the input voltage Vin of the LED lamp 20 and the current i flowing through the LED light emitting unit 24 when the LED lamp 20 is turned on by the stabilizer 12 and the inductance values of the variable inductance units L50 and L60 are changed in accordance with the magnitude of the current i flowing through the LED light emitting unit 24 will be described, the stabilizer 12 being a constant power control inverter-type stabilizer.

In fig. 8 and 9, the same observation was made using different types of constant power control inverter-type stabilizers. Fig. 8 (a) and 9 (a) are graphs in which the input voltage Vin of the LED lamp 20 is observed when the total inductance value of the variable inductance parts L50 and L60 is 100 μ H, and the vertical axis corresponds to 50V/div. Fig. 8 (b) and 9 (b) are graphs in which the current i flowing through the LED light emitting unit 24 is observed when the total inductance value of the variable inductance units L50 and L60 is 100 μ H, and the vertical axis corresponds to 200 mA/div. On the other hand, fig. 8 (c) and 9 (c) are graphs in which the input voltage Vin of the LED lamp 20 is observed when the total inductance value of the variable inductance parts L50 and L60 is 400 μ H, and the vertical axis corresponds to 50V/div. Fig. 8 (d) and 9 (d) are graphs in which the current i flowing through the LED light emitting unit 24 is observed when the total inductance value of the variable inductance units L50 and L60 is 400 μ H, and the vertical axis corresponds to 200 mA/div.

The resistance value of the resistor R31 in the current detector 31 is 1 Ω, and when the voltage across the resistor R31 is 390mV, that is, when the magnitude of the current flowing through the LED light emitting unit 24 is 390mA, the threshold is set so that the total inductance value of the variable inductance units L50 and L60 is switched from 100 μ H (mode 2) to 400 μ H (mode 1) when the threshold is exceeded.

From fig. 8 and 9, it is observed that when the total inductance value of the variable inductance parts L50 and L60 is changed greatly from 100 μ H to 400 μ H, the output voltage of the inverter-type stabilizer is increased, the output current is controlled to be small, and the stabilization is performed at 390mA or less within a predetermined range (L value non-variable region).

Next, with reference to fig. 10 to 12, respective observed waveforms of the input voltage Vin of the pair of input terminal portions (between the input terminal portion 20a and the input terminal portion 20 c), the voltage Vg1 of the gate terminal of the switching element Q1, the current sensor terminal voltage Vcs as the #2 pin of the integrated circuit IC1, the voltage Vg2 of the gate terminal of the switching element Q2, and the current i flowing through the LED light emitting unit 24 according to the respective aspects of the stabilizer 12 will be described.

The gate terminal voltages Vg1, Vg2 and the current sensor terminal voltage Vcs are measured with the GND terminal TG of the PWM control unit 25 as a reference (ground level).

The current i flowing through the LED light emitting unit 24 shown in fig. 10 (e), 11 (e), and 12 (e) is obtained by flowing the total current flowing through the LED light emitting unit 24 (total of 90 LEDs) into the insertion resistor (1 Ω) and observing the amount of voltage drop applied to the resistor, and the vertical axis of fig. 10 (e) and 11 (e) corresponds to 500mA/div, and the vertical axis of fig. 12 (e) corresponds to 200 mA/div.

First, fig. 10 (a) to (e) show the case where the glow-start type (2-time voltage 200V/2-time current 0.42A) is used as the stabilizer 12, fig. 10 (a) shows the waveform of the input voltage Vin, fig. 10 (b) shows the waveform of the voltage Vg1 of the gate terminal of the switching element Q1, fig. 10 (c) shows the waveform of the current sensor terminal voltage Vcs of the integrated circuit IC1, fig. 10 (d) shows the waveform of the voltage Vg2 of the gate terminal of the switching element Q2, and fig. 10 (e) shows the waveform of the current i flowing through the LED light emitting unit 24.

First, as shown in fig. 10 (a), 60.1Hz is observed as a commercial frequency as the frequency of the waveform of the input voltage Vin.

Since this frequency is lower than the cutoff frequency set to about 5kHz, the oscillation period t is output during actual measurement by pulse driving of the integrated circuit IC1 of the PWM control unit 25 as shown in fig. 10 (b)_OSC(μ s) is the voltage Vg1 of the gate terminal of the switching element Q1 of about 22.78 (μ s).

Here, the switching element Q1 alternately inputs a high-level (about DC7.5V) voltage and a low-level (about 0V) voltage to the gate terminal at a duty ratio of about 33%, and performs pulse driving at a frequency of about 43.9 kHz.

This is based on the PWM-controlled operation of the integrated circuit IC1 that outputs a voltage of a high level (about DC7.5V) to the gate terminal of the switching element Q1 until the current sensor terminal voltage Vcs reaches about DC250mV, and outputs a voltage of a low level (about 0V) to the gate terminal of the switching element Q1 if the current sensor terminal voltage Vcs reaches about DC250mV, as shown in fig. 10 (c).

Here, if a voltage of a high level (about DC7.5V) is input to the gate terminal of the switching element Q1 and the switching element Q1 is turned ON, a current flows into the resistors R3 to R5, so that the current i flowing through the LED light emitting unit 24 linearly increases, but if a voltage of a low level (about 0V) is input to the gate terminal of the switching element Q1, the switching element Q1 is turned OFF, so that the current sensor terminal voltage Vcs decreases to a ground level (0V).

On the other hand, since the frequency of the waveform of the input voltage Vin is lower than the cutoff frequency set to about 5kHz, only about DC50mV is input to the gate terminal of the switching element Q2 by the high-pass filter circuit, and the switching element Q2 is in the OFF state as shown in fig. 10 (d), so that a current does not flow from the drain terminal to the source terminal.

Therefore, as shown in fig. 10 (e), the current i flowing through the LED light emitting unit 24 flows in synchronization with the voltage Vg1 of the gate terminal of the switching element Q1, rises when the switching element Q1 is in the ON state, and starts to fall when the switching element Q1 is in the OFF state (the current i does not immediately fall to 0A due to the back electromotive force obtained by the choke coils L1 to L4).

That is, as shown in fig. 10 (b), the current i flowing through the LED light emitting unit 24 is PWM-controlled by the pulse driving of the PWM control unit 25 at a frequency of about 43.9 kHz.

As a result, as shown in fig. 10 e, the current i flowing through the LED light emitting unit 24 was output in a pulse form (triangular wave) of 43.7kHz higher than 5kHz as the cutoff frequency in the frequency measurement, and was observed to be about 192.2mA in the effective value (RMS value) measurement.

Next, fig. 11 (a) to (e) show the case where the fast start type (2-time voltage 190V/2-time current 0.42A) is used as the stabilizer 12, fig. 11 (a) shows the waveform of the input voltage Vin, fig. 11 (b) shows the waveform of the voltage Vg1 of the gate terminal of the switching element Q1, fig. 11 (c) shows the waveform of the current sensor terminal voltage Vcs of the integrated circuit IC1, fig. 11 (d) shows the waveform of the voltage Vg2 of the gate terminal of the switching element Q2, and fig. 11 (e) shows the waveform of the current i flowing in the LED light emitting section 24.

First, as shown in fig. 11 (a), 60.1Hz is observed as the frequency of the waveform of the input voltage Vin.

Since this frequency is lower than the cutoff frequency set to about 5kHz, the oscillation period t is actually output by the pulse driving of the integrated circuit IC1 of the PWM control unit 25 as shown in fig. 11 (b)_OSC(μ s) is the voltage Vg1 of the gate terminal of the switching element Q1 of about 22.78 (μ s).

Here, the switching element Q1 alternately inputs a high-level (about DC7.5V) voltage and a low-level (about 0V) voltage to the gate terminal at a duty ratio of about 43%, and performs pulse driving at a frequency of about 43.9 kHz.

This is based on the PWM-controlled operation of the integrated circuit IC1 that outputs a high-level (about DC7.5V) voltage to the gate terminal of the switching element Q1 until the current sensor terminal voltage Vcs reaches about DC250mV as shown in fig. 11 (c), and outputs a low-level (about 0V) voltage to the gate terminal of the switching element Q1 if the current sensor terminal voltage Vcs reaches about DC250 mV.

Here, if a high-level (about DC7.5V) voltage is input to the gate terminal of the switching element Q1 and the switching element Q1 is turned ON, a current flows through the resistors R3 to R5, so the current i flowing through the LED light emitting unit 24 rises linearly, but if a low-level (about 0V) voltage is input to the gate terminal of the switching element Q1, the switching element Q1 is turned OFF, so the current sensor terminal voltage Vcs falls to the ground level (0V).

On the other hand, since the frequency of the waveform of the input voltage Vin is lower than the cutoff frequency set to about 5kHz, only about DC50mV is input to the gate terminal of the switching element Q2 by the high-pass filter circuit, and the switching element Q2 is in the OFF state as shown in fig. 11 (d), so that a current does not flow from the drain terminal to the source terminal.

Therefore, as shown in fig. 11 (e), the current i flowing through the LED light emitting unit 24 flows in synchronization with the voltage Vg1 of the gate terminal of the switching element Q1, rises when the switching element Q1 is in the ON state, and starts to fall when the switching element Q1 is in the OFF state (the current i does not immediately fall to 0A due to the back electromotive force obtained by the choke coils L1 to L4).

That is, as shown in fig. 11 (b), the current i flowing through the LED light emitting unit 24 is PWM-controlled by the pulse driving of the PWM control unit 25 at a frequency of about 43.9 kHz.

As a result, as shown in fig. 11 e, the current i flowing through the LED light emitting unit 24 was output in a pulse form (triangular wave) of 43.6kHz higher than 5kHz as the cutoff frequency in the frequency measurement, and was observed to be about 195.7mA in the effective value (RMS value) measurement.

Finally, fig. 12 (a) to (e) show the case where an inverter type (2-time voltage 280V/2-time current 0.225A at no load) is used as the stabilizer 12, fig. 12 (a) shows the waveform of the input voltage Vin, fig. 12 (b) shows the waveform of the voltage Vg1 at the gate terminal of the switching element Q1, fig. 12 (c) shows the waveform of the current sensor terminal voltage Vcs of the integrated circuit IC1, fig. 12 (d) shows the waveform of the voltage Vg2 at the gate terminal of the switching element Q2, and fig. 12 (e) shows the waveform of the current i flowing through the LED light emitting unit 24.

First, as shown in fig. 12 (a), in the waveform of the input voltage Vin, the period t1 becomes about 13.7 (μ s), and 73.0kHz is observed as the frequency.

Since this frequency is higher than the cutoff frequency set at about 5kHz, a high-level (about DC 14V) voltage Vg2 is input to the gate terminal of the switching element Q2 as shown in fig. 12 d, and the switching element Q2 is always in the ON state.

However, since the resistor R3, the resistor R4, and the resistor R5 are connected in parallel between the terminal T9 and the terminal TG as described above, the current i flowing through the LED light emitting unit 24 hardly flows into the PWM control unit 25, and flows directly from the cathode-side terminal TK of the LED light emitting unit 24 to the ground-side output terminal T5 of the rectifier circuit unit 22 via the GND terminal TG of the PWM control unit 25.

As a result, since the current i does not flow into the resistors R3 to R5, the current sensor terminal voltage Vcs is constant at the ground level (0V) as shown in fig. 12 c, the duty ratio of the drive pulse becomes 100% as shown in fig. 12 b, the voltage Vg1 of the gate terminal of the switching element Q1 in the PWM control unit 25 is always at the high level (about DC7.5V), and the switching element Q1 is in the ON state.

Therefore, PWM control unit 25 does not perform PWM control of current i flowing through LED light emitting unit 24.

Then, as shown in fig. 12 (e), the current i flowing through the LED light emitting unit 24 is not PWM-controlled by the PWM control unit 25, and becomes a waveform in which the input voltage Vin is full-wave rectified, and is observed to be about 199.3mA in the measurement of the effective value (RMS value).

Since PWM control is not performed by pulse driving of PWM control unit 25, period t2 of the ripple voltage waveform amount superimposed on the direct current becomes about 6.9 (μ s), and the frequency of current i flowing through LED light emitting unit 24 is observed to be about 145.4kHz that is 2 times the frequency of input voltage Vin.

Therefore, it can be confirmed that the frequency of the waveform of the current i flowing through the LED light emitting unit 24 is about 2 times the frequency of the waveform of the input voltage Vin by full-wave rectification.

From the above observation, it was confirmed that, regardless of whether the ballast 12 of the lighting device 10 is of the glow start type, the rapid start type, or the inverter type, 190mA to 200mA was obtained as an effective value (RMS value) of the current i flowing through the LED light emitting unit 24 in actual measurement, and the lighting device could be used for lighting.

Meanwhile, it has been confirmed that, when the ballast 12 is of the glow start type or the rapid start type, the frequency of the input voltage Vin is about 60Hz, and therefore, the PWM control unit 25 PWM-controls the current i flowing through the LED light emitting unit 24 by pulse driving at a frequency of about 43.6 to 43.7kHz higher than 5kHz of the cutoff frequency.

On the other hand, it was confirmed that, when the stabilizer 12 is of the inverter type, the frequency of the input voltage Vin is about 73.0kHz higher than 5kHz of the cutoff frequency, and therefore, the current i flowing through the LED light emitting unit 24 is PWM-controlled without pulse driving of about 145.4kHz and the PWM control unit 25.

The technical scope of the present invention is not limited to any of the above-described embodiments, and various modifications can be made within the scope shown in the claims, and modifications of the embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention.

For example, in the present embodiment, the form in which the PWM control unit 25, the smoothing circuit unit 23, and the bypass circuit unit 26 are provided so that the lighting for illumination that can be lit can be performed by PWM control using pulse driving, regardless of whether the ballast of the fluorescent lamp lighting device is of the glow start type, the rapid start type, or the inverter type, so long as it is exchanged with a fluorescent lamp (or an LED lamp) mounted from the front is exemplified, but as shown in fig. 13 which is one of the modified examples, the LED lamp 200 may be provided without the PWM control unit 25, the smoothing circuit unit 23, and the bypass circuit unit 26 shown in fig. 1. In fig. 13, elements having the same functions as those of the elements shown in fig. 1 are denoted by the same reference numerals.

Here, since the LED lamp 200 does not include the PWM control unit 25, the smoothing circuit unit 23, and the bypass circuit unit 26, it cannot perform PWM control by pulse driving according to the frequency of the ac current input to the pair of input terminal units, and therefore, when the LED lamp is mounted on a glow start type or rapid start type ballast, it cannot perform PWM control by pulse driving with a high frequency, but when the LED lamp is mounted on an inverter type ballast, it is possible to stabilize the current i flowing through the LED light emitting unit 24 within a predetermined range as described above.

The pair of input terminal portions means that at least one pair of input terminal portions is included, and when there are 4 (2 on one side) input terminal portions in total, for example, as in the case of terminals at both end portions of a straight tube type fluorescent lamp, external ac current may be input to at least 2 of the input terminal portions (either one of the 2 terminals on one side or both sides).

In the description of the present embodiment, it is assumed that, when 2 terminals are simply connected to each other via different terminals by wiring, the 2 terminals are directly connected to each other (at the same potential) regardless of wiring resistance or the like.

The predetermined frequency for dividing the frequency of the ac current input to the pair of input terminal units is preferably about 5kHz as a commercial frequency (50 Hz/60 Hz) for dividing the stabilizer into a glow start type and a rapid start type and a high frequency (about 20 to 100 kHz) for dividing the stabilizer into an inverter type, but may be set appropriately so as to be a desired frequency by changing the circuit constant of the high-pass filter circuit within a frequency range of more than 65Hz and less than 20 kHz.

Similarly, the frequency and duty ratio of the pulse driving controlled by the PWM control unit may be set by appropriately setting the resistance, the driving voltage, and the like connected to each pin within the specification range of the integrated circuit IC1, taking into account the current (illuminance) flowing through the LED light-emitting unit, the heat generation of the switching element of the PWM control unit, and the like.

In particular, the circuit configuration and the circuit constant in the circuit diagram for reference may be appropriately selected within the range included in the technical scope of the present invention, unless otherwise apparent from the description of the above embodiments, as long as the desired object of the present invention is achieved and the desired effect is obtained.

Next, a case will be described in which the LED lamp 50 and the LED lamp 60 having the same configuration as the LED lamp 20 are connected in series and mounted on the series type rapid stabilizer to be lit up, with reference to fig. 14 (a) and (b).

First, as shown in fig. 14 a, if a plurality of resistors R20, R21, zener diode D20, and R22 are connected in series between the High Voltage (HV) side output terminal T7 and the ground side output terminal T5, and a direct current voltage (a voltage which is less than about DC250mV and is proportional to the magnitude of the High Voltage (HV)) divided by the resistor R22 is input to the #7 pin of the integrated circuit IC1, the threshold voltage can be varied in proportion to the magnitude of the voltage input to the pair of input terminal sections.

For example, if 1M Ω is selected as the resistance value of the resistor R20, 1M Ω is selected as the resistance value of the resistor R21, 51V is selected as the zener voltage of the zener diode D20, 3.65k Ω is selected as the resistance value of the resistor R22, and 1 μ F is selected as the capacitance of the capacitor C20, about 215mV is input to the #7 pin of the integrated circuit IC1 in actual measurement when 165V is output to the High Voltage (HV) side output terminal T7.

In this way, since the voltage input to the pair of input terminal portions and the current flowing through the LED light-emitting portion controlled by PWM increase and decrease in proportion to each other, the input impedance of the entire LED lamp as viewed from the pair of input terminal portions is made positive (the current flowing increases in proportion to the increase in the input voltage).

Therefore, even when the LED lamp 50 and the LED lamp 60 having the same configuration as the LED lamp 20 of the present embodiment are connected in series in the series-type snap-action stabilizer as shown in fig. 14 (b), since the voltages inputted from the series-type snap-action stabilizer are proportionally distributed according to the respective input impedances, the same drive current can be easily supplied to both of them, and the series connection of the LED lamps of the present embodiment can be realized.

Industrial applicability

As described above, the LED lamp, the lighting device including the LED lamp, and the current control method of the LED lamp according to the present invention can be applied to an LED lamp in which the magnitude of the current flowing through the LED light emitting portion can be stabilized within a predetermined range by exchanging the LED lamp with a fluorescent lamp (or the LED lamp) mounted in the past even if the stabilizer of the fluorescent lamp lighting device is of the constant power control type, an illumination device including the LED lamp, and an application as the current control method of the LED lamp.

Claims (6)

1. An LED lamp including a pair of input terminal portions, a rectifier circuit portion that rectifies an AC current input from the outside to a DC current, and an LED light emitting portion that emits light by energization of the DC current output from the rectifier circuit portion, the LED lamp comprising:

a variable inductance section for flowing an alternating current flowing from one of the pair of input terminal sections to the other input terminal section through the rectifier circuit section in a circuit between the pair of input terminal sections and the rectifier circuit section;

a current detection unit that detects a magnitude of a direct current flowing into the LED light emitting unit in a circuit between the rectifier circuit unit and the LED light emitting unit; and

an inductance variable control unit for varying an inductance value of the variable inductance unit in accordance with a magnitude of the direct current detected by the current detection unit,

a PWM control unit for PWM-controlling a current flowing through the LED light emitting unit according to a duty ratio is provided in a circuit between the rectifier circuit unit and the LED light emitting unit,

the PWM control unit performs the PWM control of the current flowing through the LED light emitting unit or does not perform the PWM control of the current flowing through the LED light emitting unit in accordance with the frequency of the AC current inputted to the outside of the pair of input terminal units,

when the PWM control unit does not perform the PWM control, the current detection unit detects a magnitude of a dc current flowing through the LED light emitting unit, and the inductance variable control unit varies the inductance value of the variable inductance unit in accordance with the magnitude of the dc current.

2. The LED lamp of claim 1, wherein:

a threshold element for passing an alternating current flowing from one of the pair of input terminal portions to the other input terminal portion through the rectifier circuit portion is provided in the circuit between the pair of input terminal portions and the rectifier circuit portion,

the threshold element is short-circuited at both ends thereof after a predetermined time has elapsed since an alternating current exceeding a predetermined threshold value is inputted to the pair of input terminal sections from the outside,

the inductance variable control unit may vary the inductance value of the variable inductance unit according to a magnitude of the direct current detected after both ends of the threshold element are short-circuited.

3. The LED lamp of claim 1 or 2, wherein:

a circuit interrupting portion capable of interrupting an alternating current flowing from one of the pair of input terminal portions to the other input terminal portion through the rectifier circuit portion is provided in the circuit between the pair of input terminal portions and the rectifier circuit portion,

the circuit interrupting unit interrupts the alternating current when the magnitude of the direct current detected by the current detecting unit exceeds a predetermined upper limit value or falls below a predetermined lower limit value.

4. An illumination device, characterized by: comprising the LED lamp of claim 1 or 2.

5. An illumination device, characterized by: comprising the LED lamp of claim 3.

6. A current control method for an LED lamp including a pair of input terminal portions, a rectifier circuit portion for rectifying an ac current inputted from the outside to a dc current, and an LED light emitting portion for emitting light by energization of the dc current outputted from the rectifier circuit portion, the method comprising:

a step of flowing an alternating current from one of the pair of input terminal portions to the other input terminal portion through the rectifier circuit portion via the variable inductance portion in a circuit between the pair of input terminal portions and the rectifier circuit portion;

a PWM control unit that can PWM-control a current flowing through the LED light emitting unit according to a duty ratio in a circuit between the rectifier circuit unit and the LED light emitting unit, the PWM control of the current flowing through the LED light emitting unit being performed or not being performed in accordance with a frequency of an alternating current input to the outside of the pair of input terminal units;

detecting a magnitude of a direct current flowing through the LED light emitting unit in a circuit between the rectifier circuit unit and the LED light emitting unit when the PWM control unit does not perform the PWM control; and

a step of changing an inductance value of the variable inductance part in accordance with the detected magnitude of the direct current when the PWM control part does not perform the PWM control,

the magnitude of the DC current flowing through the LED light emitting unit is controlled to be within a predetermined range.