JP7312028B2 - light emitting device - Google Patents

Description

The present invention relates to light emitting devices.

Conventionally, a constant-current power supply circuit in which a plurality of light-emitting modules each composed of at least one light source are connected in series; a switching element connected in parallel to any one of the light-emitting modules connected to the constant-current power supply circuit; There is a light source lighting device characterized by including a control unit that controls on/off of the switching element (see, for example, Patent Document 1).

JP 2012-099337 A

By the way, in the conventional light source lighting device, a plurality of light emitting modules connected in series are not those having a plurality of light emitting colors, which are separated for each light emitting color and connected in series. For this reason, it is not intended to adjust the amount of light emitted for each of the plurality of emitted colors.

Accordingly, it is an object of the present invention to provide a light-emitting device capable of adjusting the amount of light emitted for each of a plurality of light-emitting colors.

A light-emitting device according to an embodiment of the present invention comprises a light-emitting element light source in which two or more light-emitting element groups of the same color electrically connected in series are connected in parallel for each of the three primary colors of light, and a current output side of the light-emitting element light source. a constant current circuit connected to
and a switching element that bypasses at least one of the light emitting elements included in the light emitting element group.

It is possible to provide a light emitting device capable of adjusting the amount of light emitted for each of a plurality of colors of emitted light.

It is a figure which shows the light-emitting device 100 of embodiment. 3 is a diagram showing detailed circuit configurations of a light source section 110R, a constant current circuit 120R, and a switching element 130R; FIG. 1 is a diagram showing a configuration of a light emitting device 100; FIG. FIG. 10 is a diagram showing a simulation result of brightness of the light emitting device 100; FIG. 4 is a diagram showing an example of a duty ratio of a PWM signal when light emitting device 100 emits light; FIG. 10 is a diagram showing a light emitting device 100M including a light guide portion 150M of a modified example of the embodiment;

Embodiments to which the light emitting device of the present invention is applied will be described below.

<Embodiment>
FIG. 1 is a diagram showing a light emitting device 100 according to an embodiment. Light emitting device 100 includes light source 110 , constant current circuit 120 , and switching element 130 . As an example, the light emitting device 100 is mounted on a vehicle and used as a light source for lighting and displaying HMI (Human Machine Interface) symbols, indicators, and the like arranged around the steering wheel, dashboard, or center console. The usage pattern of the light emitting device 100 is not limited to such a usage pattern.

The light source 110 is an example of a light emitting element light source, and has light source units 110R, 110G, and 110B corresponding to the three primary colors of light, R (Red), G (Green), and B (Blue). Each of the light source units 110R, 110G, and 110B is an example of a group of two or more same-color light emitting elements electrically connected in series.

The light source unit 110R has two LEDs (Light Emitting Diodes) 111R and 112R connected in series, the light source unit 110G has two LEDs 111G and 112G connected in series, and the light source unit 110B has LEDs connected in series. It has two LEDs 111B and 112B. The LEDs 111R, 112R, 111G, 112G, 111B, and 112B are examples of light emitting elements. Also, the LEDs 111R, 111G, and 111B are examples of first light emitting elements, and the LEDs 112R, 112G, and 112B are examples of second light emitting elements.

Here, as an example, a mode will be described in which light source units 110R, 110G, and 110B, which are examples of light emitting element groups, each include two LEDs 111R, 112R, LEDs 111G, 112G, and LEDs 111B, 112B.

The anode of the LED 112R is connected to the DC power supply Vbat and supplied with the voltage Vbat. The DC power supply Vbat is here, as an example, a vehicle battery. The cathode of the LED 112R is connected to the anode of the LED 111R, and the cathode of the LED 111R is grounded through the constant current circuit 120R. Ground is an example of a reference potential point.

Similarly, the anode of the LED 112G is connected to the DC power supply Vbat and supplied with the voltage Vbat. The cathode of the LED 112G is connected to the anode of the LED 111G, and the cathode of the LED 111G is grounded through the constant current circuit 120G.

Similarly, the anode of the LED 112B is connected to the DC power supply Vbat and supplied with the voltage Vbat. The cathode of the LED 112B is connected to the anode of the LED 111B, and the cathode of the LED 111B is grounded via the constant current circuit 120B.

Due to this connection relationship, the LEDs 111R and 112R, the LEDs 111G and 112G, and the LEDs 111B and 112B are connected in parallel.

Constant current circuit 120 is a general term for three constant current circuits 120R, 120G, and 120B corresponding to light source units 110R, 110G, and 110B. Hereinafter, the constant current circuits 120R, 120G, and 120B are simply referred to as the constant current circuit 120 unless otherwise distinguished.

The constant current circuits 120R, 120G, 120B are connected between the cathodes of the LEDs 111R, 111G, 111B and the ground, respectively, and draw current from the cathodes of the LEDs 111R, 111G, 111B toward the ground.

The current values output by the constant current circuits 120R, 120G, and 120B are controlled based on commands input from an ECU (Electronic Control Unit) or the like that controls the illuminance of a vehicle indicator or the like.

The switching element 130 is a general term for three switching elements 130R, 130G, and 130B corresponding to the light source units 110R, 110G, and 110B. Hereinafter, the switching elements 130R, 130G, and 130B are simply referred to as the switching element 130 when not particularly distinguished.

Switching elements 130R, 130G, 130B are connected between the anodes and cathodes of LEDs 112R, 112G, 112B, respectively. The switching elements 130R, 130G, and 130B are controlled to open and close by an ECU that controls the illuminance of vehicle indicators and the like, and bypass the LEDs 112R, 112G, and 112B when turned on (conducting state).

As such switching elements 130R, 130G, and 130B, for example, p-channel MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) can be used.

FIG. 2 is a diagram showing detailed circuit configurations of the light source unit 110R, the constant current circuit 120R, and the switching element 130R. In FIG. 2, the circuit configuration of the red (R) system light source unit 110R, the constant current circuit 120R, and the switching element 130R will be described as an example. The circuit configurations of the element 130G, the blue (B) system light source section 110B, the constant current circuit 120B, and the switching element 130B are the same.

FIG. 2 also shows an ECU 50 that controls the illuminance of a vehicle indicator or the like. The ECU 50 has terminals 51 , 52 and 53 . The ECU 50 outputs from a terminal 51 a PWM signal for driving the LEDs 111R and 112R or the LED 111R by PWM (Pulse Width Modulation). The ECU 50 also outputs a current switching signal for switching on/off the transistor 123 of the constant current circuit 120R from the terminal 52, and outputs a bypass signal for switching the switching element 130R on/off from the terminal 53.

Here, the ECU 50 will be described as having the red (R) system light source unit 110R, the constant current circuit 120R, and the switching element 130R. 120G, switching element 130G, blue (B) system light source unit 110B, constant current circuit 120B, and switching element 130B also output PWM signals, current switching signals, and bypass signals.

The duty ratio of the PWM signal can be controlled differently among the light source units 110R, 110G, and 110B. Also, the current switching signal may have different on/off states for the constant current circuits 120R, 120G, and 120B, and the bypass signals may have different on/off states for the switching elements 130R, 130G, and 130B.

The constant current circuit 120R has a transistor 121, an operational amplifier 122, a transistor 123, and resistors 124-127.

The transistor 121 has a collector terminal connected to the cathode of the LED 111 R, an emitter terminal grounded via a resistor 124 , and a base terminal connected to the output terminal of the operational amplifier 122 . The transistor 121 is controlled to be on (conducting state)/off (non-conducting state) by the output of the operational amplifier 122 .

The non-inverting input terminal of operational amplifier 122 is connected to terminal 51 of ECU 50 via resistor 126 , to ground via resistor 125 , and to the collector terminal of transistor 123 via resistor 127 . The inverting input terminal of operational amplifier 122 is connected to the emitter terminal of transistor 121 . Also, the output terminal of the operational amplifier 122 is connected to the base terminal of the transistor 121 .

Transistor 123 has a collector terminal connected to the non-inverting input terminal of operational amplifier 122 and resistors 125 and 126 via resistor 127 , an emitter terminal connected to ground, and a base terminal connected to terminal 52 . By passing a current through the base of the transistor 123, the transistor 123 can be turned on/off, and the current value of constant current control can be switched.

Resistor 124 has a resistance value for limiting the current flowing through LEDs 111R and 112R to a predetermined value or less. Resistors 125 and 126 form a voltage dividing resistor circuit that adjusts the voltage value input to the non-inverting input terminal of operational amplifier 122 . When the transistor 123 is off and the switching element 130 is off, the voltage of the PWM signal output from the terminal 51 of the ECU 50 is divided by the resistors 125 and 126, and the output of the operational amplifier 122 becomes the first H( High) level. The first H level is higher than the second H level, which will be described later, and the first H level PWM signal output from the operational amplifier 122 causes the LEDs 111R and 112R to emit light with high luminance. If the duty ratio of the PWM signal is set to the maximum value in this state, the brightness of the light emitting device 100 (the brightness by the LEDs 111R and 112R) becomes maximum. It should be noted that increasing the duty ratio of the PWM signal means increasing the proportion of the H level section.

A resistor 127 is connected between the non-inverting input terminal of the operational amplifier 122 , the connection point between the resistors 125 and 126 , and the collector of the transistor 123 . Resistor 127 is connected in parallel to resistor 125 between the connection point of resistors 125 and 126 and ground when transistor 123 is on and switching element 130 is on. It is provided to lower the potential at the connection point of 125 and 126 (the voltage between both terminals of resistor 125). In this state, the output of the operational amplifier 122 becomes the second H level PWM signal, and the LED 111R can be made to emit light with low luminance while the LED 112R is bypassed and turned off. By setting the duty ratio of the PWM signal to the minimum value, the luminance of the light emitting device 100 (luminance by only the LED 111R) is minimized. The pulse width of the second H level PWM signal is about 1/10 of the pulse width of the first H level PWM signal.

Since the switching element 130R is, for example, a p-channel MOSFET, it is turned on (conducting state) when the bypass signal output from the terminal 53 of the ECU 50 is at L (Low) level, and is turned off when the bypass signal is at H level. become.

The switching element 130R is provided to bypass the LED 112R and turn it off when the luminance of the light emitting device 100 is reduced. Therefore, for example, when the vehicle is in a bright place such as in the daytime, the switching element 130R is turned off in order to increase the brightness of the light emitting device 100. FIG. This is for obtaining high brightness by causing both the LEDs 111R and 112R to emit light. Further, for example, when the vehicle is in a dark place such as at night or in a tunnel, the switching element 130R is turned on to reduce the brightness of the light emitting device 100. FIG.

FIG. 3 is a diagram showing the configuration of the light emitting device 100. As shown in FIG. Light emitting device 100 includes light source 110 , substrate 140 , light guide section 150 and panel 160 . Here, the constant current circuit 120, the switching element 130 and the like are omitted.

The light source 110 is divided into LEDs 111R, 111G, 111B and LEDs 112R, 112G, 112B and mounted on the surface of the substrate 140 .

The light guide portion 150 is a light guide member that guides light emitted from the LEDs 111R, 111G, and 111B and the LEDs 112R, 112G, and 112B, and is made of acrylic resin or the like.

The light guide section 150 has light entrance sections 151 and 152 and a light exit section 153 . The light entrance portions 151 and 152 are portions into which light is incident from the light source 110. The light entrance portion 151 is arranged to face the LEDs 111R, 111G and 111B, and the light entrance portion 152 faces the LEDs 112R, 112G and 112B. are placed.

The light incident from the light entrance portions 151 and 152 propagates inside the light guide portion 150 and is emitted from the light exit portion 153 toward the symbol 161 on the panel 160 .

FIG. 4 is a diagram showing simulation results of luminance of the light emitting device 100. As shown in FIG. In FIG. 4 , the horizontal axis represents time, and the vertical axis represents luminance of the light emitting device 100 . Here, the LEDs 111G, 111B, 112G, and 112B are also connected to constant current circuits 120G and 120B having the same circuit configuration as the constant current circuit 120R shown in FIG. It is assumed that PWM signals for the green (G) system and the blue (B) system are output. However, in the description of FIG. 4, as an example, it is assumed that the duty ratios of the PWM signals for the red (R) system, the green (G) system, and the blue (B) system are equal.

At time t1, the ECU 50 outputs a PWM signal having a duty ratio of about 50% and a predetermined large pulse width from the terminal 51, outputs an L level current switching signal from the terminal 52, and outputs an H level bypass signal from the terminal 53. Output a signal. In this state, the transistor 123 and the switching element 130 are turned off, the operational amplifier 122 outputs the first H level PWM signal, and the LEDs 111R, 112R, 111G, 112G, 111B and 112B are lit. This state continues until time t2, and high luminance of light emitting device 100 is obtained. A current flowing through the LEDs 111R, 112R, 111G, 112G, 111B, and 112B is, for example, approximately 20 mA.

At time t3, the ECU 50 switches the current switching signal output from the terminal 52 to H level. The PWM and bypass signals are unchanged. In this state, the transistor 123 is turned on, the switching element 130 is turned off, and the operational amplifier 122 outputs the second H level PWM signal. Therefore, the LEDs 111R, 112R, 111G, 112G, 111B and 112B are lit. This state continues until time t4. Since the current flowing through the LEDs 111R, 112R, 111G, 112G, 111B, and 112B is, for example, about 2 mA, the brightness of the light-emitting device 100 is about 1/10 of the period from time t1 to t2.

At time t5, the ECU 50 returns the current switching signal output from the terminal 52 to L level, and switches the bypass signal output from the terminal 53 to H level. The PWM signal is unchanged.

In this state, transistor 123 is turned off and switching element 130 is turned on. Therefore, the operational amplifier 122 outputs the first H-level PWM signal, the LEDs 111R, 111G, and 111B are turned on, and the LEDs 112R, 112G, and 112B are turned off. This state continues until time t6. As an example, the current flowing through the LEDs 111R, 111G, and 111B is approximately 20 mA, and the current flowing through the LEDs 112R, 112G, and 112B is 0 mA. become.

At time t7, the ECU 50 switches the current switching signal output from the terminal 52 to H level, and holds the bypass signal output from the terminal 53 at H level. The PWM signal is unchanged.

In this state, transistor 123 and switching element 130 are switched on. Therefore, the operational amplifier 122 outputs the second H-level PWM signal, the LEDs 111R, 111G, and 111B are turned on, and the LEDs 112R, 112G, and 112B are turned off. This state continues until time t8. For example, the current flowing through the LEDs 111R, 111G, and 111B is approximately 2 mA, and the current flowing through the LEDs 112R, 112G, and 112B is 0 mA. become.

As described above, by switching the current switching signal, the output of the operational amplifier 122 can be switched between the first H level PWM signal and the second H level PWM signal. The number of LEDs running can be set to two or one for each of the three primary colors of light. Furthermore, by adjusting the duty ratio of the PWM signal output by the ECU 50, the light emission time of each LED can be adjusted, and the luminance of the light emitting device 100 can be adjusted.

FIG. 5 is a diagram showing an example of the duty ratio of the PWM signal when light emitting device 100 emits light. In FIG. 5, when the light-emitting device 100 emits monochromatic red (R), monochromatic green (G), monochromatic blue (B), and white, luminance is 100%, 0.5 % (PWM signal only), 0.5% (PWM signal+current switching signal), and 0.5% (PWM signal+current switching signal+bypass signal).

Here, setting the luminance to 0.5% (only the PWM signal) means controlling the duty ratio of the PWM signal while turning off the transistor 123 and the switching elements 130R, 130G, and 130B by the current switching signal and the bypass signal. This means that the brightness is set to 0.5% just by doing so.

Further, setting the luminance to 0.5% (PWM signal + current switching signal) means that the current switching signal and the bypass signal turn on the transistor 123 and turn off the switching elements 130R, 130G, and 130B. It refers to setting the luminance to 0.5% by controlling the duty ratio of the signal.

Setting the luminance to 0.5% (PWM signal+current switching signal+bypass signal) means that the current switching signal and the bypass signal turn on the transistor 123 and the switching elements 130R, 130G, and 130B, and the PWM signal to set the luminance to 0.5% by controlling the duty ratio of

In order to obtain white light emission, the ratio of R:G:B should be adjusted to 3:7:1. When 110R, 110G, and 110B are output, the symbol luminance becomes equivalent to the case of monochromatic 100%.

The brightness is set to 100% when the inside of the vehicle is in a bright place such as during the daytime. , red (R), green (G), and blue (B) PWM signals are set to 100%. In this case, the duty of the PWM signals other than the luminescent color should be set to 0%. To obtain a single white color, the duty of the PWM signals of red (R), green (G) and blue (B) should be set to 27%, 64% and 9%.

In order to obtain single-color light emission of red (R), green (G), and blue (B) at a luminance of 0.5% (PWM signal only), red (R), green (G), and blue The duty of the PWM signal of (B) should be set to 0.50%. In this case, the duty of the PWM signals other than the luminescent color should be set to 0%. To obtain a single white color, the duty of the PWM signals of red (R), green (G), and blue (B) should be set to 0.14%, 0.32%, and 0.05%.

In addition, in order to obtain single-color light emission of red (R), green (G), and blue (B) at a luminance of 0.5% (PWM signal + current switching signal), red (R), green (G ), and the duty of the blue (B) PWM signal is set to 5.00%. In this case, the duty of the PWM signals other than the luminescent color should be set to 0%. To obtain a single white color, the duty of the PWM signals of red (R), green (G), and blue (B) should be set to 1.36%, 3.18%, and 0.45%.

To obtain single-color light emission of red (R), green (G), and blue (B) at a luminance of 0.5% (PWM signal + current switching signal + bypass signal), red (R), The duty of the green (G) and blue (B) PWM signals should be set to 10.00%. In this case, the duty of the PWM signals other than the luminescent color should be set to 0%. To obtain a single white color, the duty of the PWM signals of red (R), green (G) and blue (B) should be set to 2.73%, 6.36% and 0.91%.

Comparing brightness 0.5% (PWM signal only), brightness 0.5% (PWM signal + current switching signal), and brightness 0.5% (PWM signal + current switching signal + bypass signal), the same The PWM signal duty is increased to obtain 0.5% luminance. This is because at 0.5% (PWM signal+current switching signal), the transistor 123 is turned on and the pulse width of the PWM signal output from the operational amplifier 122 is reduced. Also, at a luminance of 0.5% (PWM signal+current switching signal+bypass signal), only the LEDs 111R, 111G, and 111B emit light, and the LEDs 112R, 112G, and 112B do not emit light (do not light up).

In the case of a luminance of 0.5% (PWM signal + current switching signal + bypass signal), the PWM signal for blue (B), which has the smallest duty ratio to obtain white, is 0.91%, and 1%. close values are obtained.

Here, for example, the luminance of the LED 111R is adjusted by inserting the collector terminal and the emitter terminal of a transistor in series between the cathode of the LED 111R and the ground, and driving the base of the transistor with a PWM signal. Similarly, the LEDs 111G and 111B are also connected to transistors and driven by PWM signals to adjust the brightness of the LEDs 111G and 111B.

In such a case, the variation in brightness of the LED 111R is about ±30%, the voltage Vbat varies from 9V to 16V, the frequency of the PWM signal is 110Hz, and the ratio between the highest brightness and the lowest brightness is 1/400. , the pulse width of the PWM signal when driving the LED 111R at the minimum luminance is about 11 μs or less. In addition to such luminance adjustment, if the LEDs 111G and 111B are also added to adjust the luminance and chromaticity balance, the pulse width will be further shortened. It is extremely difficult to stably perform PWM control with such a short pulse width.

In contrast, in the embodiment, in addition to the PWM control by the PWM signal, the amount of current flowing through the light source 110 can be adjusted using the transistor 123, the resistor 127, and the switching elements 130R, 130G, and 130B. .

Even the PWM signal for blue (B), which has the smallest duty ratio for obtaining white, has a pulse width of about 0.05 ms. Therefore, stable control becomes possible.

As described above, according to the embodiment, two LEDs 111R, 112R, LEDs 111G, 112G, and LEDs 111B, 112B connected in series are provided for each of the three primary colors of light, and the switching elements 130R, 130G that can bypass the LEDs 112R, 112G, 112B. , 130B. With such a configuration, the light emission amount can be adjusted for each of the red (R), green (G), and blue (B) emission colors.

Therefore, it is possible to provide the light emitting device 100 that can adjust the amount of light emitted for each of red (R), green (G), and blue (B) emission colors.

In addition, it is possible to secure a dynamic range for each emission color of red (R), green (G), and blue (B), making it cheaper than using a DAC (Digital to Analog Converter) to adjust the current. can be realized.

In addition, the configuration may include any one of the switching elements 130R, 130G, and 130B. With such a configuration, it is possible to provide the light emitting device 100 capable of adjusting the light emission amount for each of a plurality of light emission colors such as red (R), green (G), and blue (B).

Further, since the light source 110 capable of emitting three colors of red (R), green (G), and blue (B) is used, the multicolor light emitting device 100 can be provided by adjusting the light of the three colors. can be done. In particular, it is highly useful and highly effective to display the symbols, indicators, etc. in the interior of the vehicle in multicolor.

Further, since the light-emitting device 100 further includes the transistor 123 and the resistor 127 for adjusting the output level of the operational amplifier 122 in two stages, the dynamic range can be secured by adjusting the operational amplifier 122 in two stages, and the color tone can be improved. Adjustment is also possible.

Further, by setting the resistance value of the resistor 127 and/or the characteristics of the transistor 123 so that the two stages of the output levels of the operational amplifiers 122 of the constant current circuits 120R, 120G, and 120B are different from each other, red (R), green ( A dynamic range can be set for each of the colors G) and blue (B), enabling finer color adjustment.

A PWM signal voltage is applied from the terminal 51 of the ECU 50 to the connection point between the non-inverting input terminal of the operational amplifier 122 and the resistor 125, and the output level of the operational amplifier 122 is set in two stages by the transistor 123 and the resistor 127. By adjusting the duty ratio of the PWM signal in addition to the adjustment, the dynamic range of the light emitting device 100 can be adjusted, so a very large dynamic range can be secured.

Such a configuration realizes a dynamic range of 200 times from low luminance of 0.5% to high luminance of 100%.

Constant current control can be easily performed by passing a current through the base of the transistor 123 whose emitter terminal is grounded (emitter grounded) and whose collector terminal is connected to the non-inverting input terminal of the operational amplifier 122 . and the current can be adjusted.

In addition, since light can be emitted to the panel 160 by the light guide section 150, it is possible to provide the light emitting device 100 that can reliably guide the light emitted from the light source 110 to the panel 160 with a simple configuration.

For example, when the light emitting device 100 is used as a light source for lighting and displaying HMI symbols, indicators, etc. of a vehicle, high luminance is required when the vehicle is in a bright place such as during the daytime. , low luminance is required. The ratio of luminance has a dynamic range of 200:1 (for example, 400 cd/m ² when bright and 2 cd/m ² when dark), and can be controlled so that the luminance is constant depending on the display color. A configuration is required in which the chromaticity and luminance are not easily affected by the voltage fluctuation of .

In order to realize such a configuration, if a driver IC (Integrated Circuit) dedicated to driving the LED is used, the driver IC can control the current by the PWM signal but cannot control the current, or cannot control the current. However, there are restrictions such as inability to control by the PWM signal for each type of driver IC, which is inconvenient to use.

In contrast, in the embodiment, two LEDs 111R, 112R, LEDs 111G, 112G, and LEDs 111B, 112B connected in series are provided for each of the three primary colors of light without using a driver IC, and the LEDs 112R, 112G, 112B can be bypassed. Switching elements 130R, 130G, and 130B are provided, a transistor 123 and a resistor 127 are provided to adjust the output level of the operational amplifier 122, and a PWM signal is supplied to the connection point between the non-inverting input terminal of the operational amplifier 122 and the resistor 125. ing.

Such a configuration realizes a dynamic range of 200 times from low luminance of 0.5% to high luminance of 100%.

In addition, since the vehicle battery voltage Vbat can be used directly, an expensive power supply regulator is not required.

In addition, there are no restrictions on the interface such as the protocol of the ECU of the vehicle, and a very easy-to-use configuration can be realized.

In the above description, light source units 110R, 110G, and 110B each include two series-connected LEDs 111R, 112R, LEDs 111G, 112G, and LEDs 111B, 112B. However, the light source units 110R, 110G, 110B may include three or more series-connected LEDs. In this case, one or a plurality of switching elements 130R, 130G, and 130B may be provided so as to bypass at least one of the three or more LEDs connected in series.

Also, in the above description, the configuration in which the output level of the operational amplifier 122 is adjusted in two steps using the transistor 123 and the resistor 127 has been described. However, for example, by adjusting the base voltage of the transistor 123 stepwise, the output of the operational amplifier 122 may be adjusted in three or more steps. In this case, the dynamic range can be further improved, and finer color adjustment becomes possible.

Also, the light guide section 150 may be modified as shown in FIG. FIG. 6 is a diagram showing a light emitting device 100M including a light guide section 150M according to a modification of the embodiment. The light guide portion 150M has light entrance portions 151M and 152M and a light exit portion 153M. The light entrance portions 151M and 152M are portions into which light is incident from the light source 110. The light entrance portion 151M is arranged to face the LEDs 111R, 111G and 111B, and the light entrance portion 152M faces the LEDs 112R, 112G and 112B. are placed.

The light guide portion 150M is arranged so that the optical axis C1 of the LEDs 111R, 111G, and 111B, the optical axis C2 of the light entrance portion 151M, and the optical axis C3 of the light exit portion 153M are aligned. , are arranged to merge at an angle with respect to the optical path between the light entrance portion 151M and the light exit portion 153M.

Such a light guiding portion 150M can efficiently guide the light emitted from the LEDs 111R, 111G, and 111B to the light emitting portion 153M. In particular, when the LEDs 112R, 112G, and 112B are bypassed by the switching elements 130R, 130G, and 130B, the LEDs 112R, 112G, and 112B do not light up, and the LEDs 111R, 111G, and 111B emit light, thereby further improving the luminous efficiency. be able to.

Although light emitting devices according to exemplary embodiments of the present invention have been described above, the present invention is not limited to the specifically disclosed embodiments, and without departing from the scope of the claims, Various modifications and changes are possible.

100 Light Emitting Device 110 Light Source 110R, 110G, 110B Light Source Part 111R, 112R, 111G, 112G, 111B, 112B LED
120 constant current circuit 130 switching element 150, 150M light guide section

Claims (6)

a light emitting element light source in which two or more light emitting element groups of the same color electrically connected in series are connected in parallel for each of the three primary colors of light;
a constant current circuit connected to the current output side of the light emitting element light source;
a switching element that bypasses at least one of the light emitting elements included in the light emitting element group;
The constant current circuit is
For each of the light emitting element groups connected in series for each of the three primary colors of light, the amount of current output is controlled in at least two stages,
an operational amplifier having an output terminal connected between the current output side of the light emitting element group and a reference potential point;
a limiting resistor connected between the non-inverting input terminal of the operational amplifier and the reference potential point;
a transistor having a collector terminal connected to the non-inverting input terminal of the operational amplifier and having an emitter terminal connected to the reference potential point;
and controlling the voltage across the limiting resistor by controlling the control voltage applied to the base terminal of the transistor, thereby controlling the amount of current output. 2. The light-emitting device according to claim 1, wherein the switching element is provided for each of the three primary colors of light so as to bypass one of the groups of light-emitting elements connected in series for each of the three primary colors of light. 3. The light emitting device according to claim 1 , wherein said constant current circuit sets the current output amount set by said stepwise control to a different current output amount for each of said three primary colors of light. A pulse width modulation signal is applied to a connection point between the non-inverting input terminal of the operational amplifier of the constant current circuit and the limiting resistor,
4. The light emitting device according to any one of claims 1 to 3, wherein said current output amount is further controlled by the duty ratio of said pulse width modulation signal in addition to controlling the voltage across said limiting resistor. a light emitting element light source in which two or more light emitting element groups of the same color electrically connected in series are connected in parallel for each of the three primary colors of light;
a constant current circuit connected to the current output side of the light emitting element light source;
a switching element that bypasses at least one of the light emitting elements included in the light emitting element group;
The light emitting element groups for each of the three primary colors of the light of the light emitting element light source have a first light emitting element to which the switching element is not connected and a second light emitting element to which the switching element is connected in parallel,
A first light entrance section provided facing three first light emitting elements corresponding to the three primary colors of light, and a second light entrance section provided facing three second light emitting elements corresponding to the three primary colors of light and a light emitting portion for outputting the light incident from the first light entering portion and the second light entering portion. In the light guide section, the first light entrance axis of the first light entrance section and the light exit axis of the light exit section are aligned, and the second light entrance axis of the second light entrance section is aligned with the first light entrance section. 6. A light emitting device according to claim 5 , angled with respect to an optical axis and said output axis.

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