JPH06317978A - Power supply device and power supply device for electrophotographic apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a high-precision power supply device with little influence of noise and a power supply device for an electrophotographic device. [Structure] A power supply circuit 2-3 is supplied with power from a commercial power supply 1 and supplies constant DC voltages V _P and V _S to a developing bias circuit 4-2 and the like arranged apart from the power supply circuit 2-3. The regulation circuit 8 arranged in the developing bias circuit 4-2 supplies power to the control circuit of the developing bias circuit 4-2. With this configuration, compared with the conventional device in which the regulation circuit 8 is arranged away from the developing bias circuit, when supplying power to the control circuit,
The influence of noise such as fluctuations in the power supply voltage is reduced, and highly accurate development bias output can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly accurate power supply device suitable for electrophotographic copying machines and printers.

[0002]

2. Description of the Related Art In electrophotographic copying machines, printers, etc. (hereinafter referred to as "electrophotographic apparatus"), a photosensitive drum is uniformly charged, or a toner is formed on an electrostatic latent image on a photosensitive drum written by a laser or the like. In the process of adhering (development) or transferring the toner image on the developed drum to the transfer paper, a high voltage power supply having various values of AC and DC is used, and the value is Depending on various conditions,
It is designed to be variable by receiving a control signal from the control circuit. A conventional example will be described below.

FIG. 5 shows a circuit block diagram of the first conventional example.

In the figure, 1 is a commercial power source having a frequency of 50 [Hz] or 60 [Hz] such as 100 [V] or 200 [V], and 2-1 is a low voltage rectifying and smoothing the commercial power source. Is a power supply circuit that generates a constant voltage DC output of. 3-1 is a control circuit for controlling output values of various high-voltage power supplies in the apparatus by a voltage level signal _VL , performing ON / OFF control, and a drive motor for the photosensitive drum and a motor for a paper transport system. It is a control circuit for controlling. 4-1 is a developing bias circuit for generating a developing bias for adhering toner to the electrostatic latent image, 5 is one of several high-voltage power supply circuits and a high-voltage power supply circuit A, and 6 is some motor control circuits. It is one motor control circuit A. The voltage V _P in the figure is a constant voltage output with a relatively large current capacity that controls the development bias and other high-voltage power supplies and motors, and V _S is a relatively high voltage that controls the power supply of the control system circuits of each circuit. It is a constant voltage with accuracy.

In the configuration shown in the drawing, in recent years, as the performance and miniaturization of the device increase, each circuit is divided for each device and each device is arranged in a narrow space.

FIG. 6 shows a circuit block diagram of another conventional example 2 which is a conventional example.

In the figure, the same reference numerals as those of the conventional example 1 are equivalent functional parts. In the conventional example 2, the highly accurate constant voltage is generated not by the power supply circuit but by the regulation circuit 7 provided separately. That is, 7 receives a constant voltage V _O from the power supply circuit 2-2 and becomes a highly accurate constant voltage V _R adjusted by the variable resistor VR (or becomes a power supply for control system circuits of various circuits). It is a regulation circuit that outputs a voltage V _S ). This configuration is an attempt to improve the developing bias and other control of the high-voltage power supply accuracy by which to be able to adjust the voltage V _R with high precision (i.e., the accuracy of the high-voltage output value).

[0008]

However, in the above-mentioned conventional example, each circuit 3, 4, 5 ... Circuits 4, 5, 6 on the side which is arranged at a distance or is controlled by the control circuit 3 ...
Are placed apart from each other, and the control signal line is placed near the high voltage line, which causes noise in the control system voltages V _R and V _S and the control signal V _L from the control circuit 7. Is a cause of overlapping. As a result, the high-voltage output vibrates, the accuracy decreases, and the like, and it has become impossible to cope with the high definition of the image quality accompanying the recent colorization.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a high-precision power supply device which is less affected by noise and a power supply device for an electrophotographic apparatus.

[0010]

In order to achieve the above-mentioned object, in the present invention, the power supply device is as shown in the following (1), and the power supply device of the electrophotographic apparatus is as follows (2), (3),
It is configured as in (4) and (5).

(1) A first power supply which is supplied with power from a commercial power supply and outputs a constant DC voltage, and a first power supply which is arranged at a position apart from the first power supply and which is supplied with power from the first power supply to provide a desired output. A power supply device comprising a second power supply to be obtained and a third power supply arranged in the second power supply for a control circuit of the second power supply.

(2) A power supply which is supplied with power from a commercial power supply and outputs a constant DC voltage, and a developing bias power supply which is arranged at a position apart from this power supply and is supplied with power from this power supply.
A power supply device for an electrophotographic apparatus, comprising: a power supply for a control circuit for the developing bias power supply, which is disposed in the developing bias power supply.

(3) A power supply which is supplied from a commercial power supply and outputs a constant DC voltage, and a developing bias power supply which is arranged at a position apart from this power supply and is supplied from this power supply.
A power supply for a control circuit of the developing bias power supply, which is arranged in the developing bias power supply, and a control device which is arranged at a position apart from the developing bias power supply and generates a digital modulation signal for controlling the developing bias power supply. And a digital demodulation means which is disposed in the developing bias power source and which demodulates the digital modulation signal and generates a signal for controlling the developing bias power source.

(4) A power supply which is supplied with power from a commercial power supply and outputs a constant DC voltage, and a developing bias power supply which is arranged at a position distant from this power supply and which is supplied with power from this power supply.
An analog modulation signal of a type resistant to noise for controlling the developing bias power source and a power source for a control circuit of the developing bias power source, which is disposed in the developing bias power source, and a position apart from the developing bias power source. A power supply device for an electrophotographic apparatus, comprising: a control device for generating a signal; and a demodulation unit that is disposed in the developing bias power source and that demodulates the analog modulated signal and generates a signal for controlling the developing bias power source.

(5) The analog modulation signal that is resistant to noise is P
The power supply for the electrophotographic apparatus according to (4), which is a WM signal, and the demodulating means includes an amplifying means for amplifying the PWM signal until the output is sufficiently saturated and a smoothing means for smoothing the output of the amplifying means. apparatus.

[0016]

In the configurations (1) to (5), since the power supply for the control circuit is provided near the control circuit, the influence of noise on the output of the power supply for the control circuit is small.

In the above configurations (3), (4) and (5),
Since the control signal supplied from the control device to the developing bias power source is a digital modulation signal or an analog modulation signal of a type resistant to noise, the influence of noise on the control signal is small.

[0018]

EXAMPLES The present invention will be described in detail below with reference to examples.

(Embodiment 1) FIG. 1 is a block diagram showing the overall configuration of a power supply system of an "electrophotographic copying machine" which is Embodiment 1. In the figure, the same reference numerals as those in the conventional example are equivalent functional parts. In this embodiment, the power supply circuit 2-3 obtains the power system voltage V _P and the control system voltage V _S and inputs these voltages to the circuits 3, 4, 5 ... 4-2 inside provided externally adjustable regulating circuit 8, the regulator circuit voltage V _R which is adjusted with high accuracy obtained by 8, such as the reference voltage for the output value control of the developing bias, control It is intended to improve the output accuracy of the developing bias by using it as a circuit voltage.

In the figure, the control system voltage V _S is output by the power supply circuit 2-3, but it is not always necessary to have such a configuration, and for example, a separate regulation circuit is provided. It may be provided and the voltage from there may be used as V _S. Further, in the figure, the voltage V _O is taken out from the power supply circuit 2-3 as the input voltage to the regulation circuit 8, but this is not always necessary. For example, the voltage V _P or V _S may be used as the input voltage. , Power supply circuit 2-
It is also possible to derive the voltage from a circuit other than 3.

FIG. 2 shows a circuit diagram of the developing bias circuit 4-2. (B) of the figure shows the regulation circuit 8, which is a 5-terminal type IC regulator (for example, SI-made by Sanken).
3000 series), voltage V _O is applied to pin 5,
1 pin as ground GND, between 3-4 pins, and 1-
Variable resistors VR1 and VR2 are connected between the four pins. The output voltage appears at the V _R end, and the desired voltage V _R can be obtained by appropriately changing the variable resistors VR1 and VR2. The capacitors C1 and C2 are smoothing capacitors.

FIG. 3A shows a developing bias DC circuit. The power system voltage V _P is used for a portion having a relatively large current value, which is used for switching driving of the transformer T by the transistor Tr, and the control system voltage V _S is using a small signal circuit relatively current value, further, as the voltage reference input of the error amplifier 9 is regulated voltage V _R of the aforementioned regulator circuit 8 relating to the detection circuit or the like, directly output accuracy for detecting an output voltage I am using. In FIG. 2, 10 is a comparator, 11 is a triangular wave oscillator, and the input of the comparator 10 is the output of the triangular wave oscillator 11 and the error amplifier 9
The output of the transformer T is PWM-controlled to obtain an output voltage corresponding to the control signal V _c sent from the control circuit 3-2 (see FIG. 1).

As described above, in this embodiment, since the regulation circuit is provided in the developing bias circuit and the output voltage thereof is used as the detecting circuit for detecting the output voltage of the developing bias,
The output accuracy of the developing bias is improved, and this accuracy can be guaranteed by the developing bias circuit alone, and the output of the developing bias is not affected by noise such as fluctuation of the power supply voltage and the quality of the copied image is improved. improves.

The output of the regulation circuit can be used for control circuits other than the above-mentioned output voltage detection circuit, if necessary.

(Embodiment 2) In this embodiment, a digital signal is used as a control signal. The overall configuration is similar to that of the first embodiment, but since digital signals are used,
The control circuit will be described with reference numeral 3-3, and the developing bias circuit with reference numeral 4-3.

FIG. 3 is a circuit diagram of the developing bias circuit 4-3 used in this embodiment. Reference numeral 12 in the figure is a D / A converter IC.

In this embodiment, the control circuit 3
From -3, a digital signal is input to control the D / A converter 12. That is, a digital signal corresponding to an analog voltage to be output and a digital signal representing the pin number (DA1, DA2, DA3, ...) Which should output the analog signal are serially input to the input DIN of the D / A converter 12. A clock signal is input to the data, a clock signal is input to the input CLK as a timing signal for storing the serial data in the internal register of the D / A converter 12 at any time, and the input LD is stored in the register after the data is transmitted. A digital signal is loaded and the digital signal is input so that a predetermined analog voltage is output from a predetermined pin. From the above digital signal input, D /
The A converter 12 divides the voltage input to the V _DD terminal into a value based on the digital signal input to the input DIN, and outputs it as a control signal to the error amplifier 9. Therefore, since the voltage accuracy of this control signal is determined by the accuracy of the base voltage V _DD , the voltage that determines the reference input voltage to the error amplifier 9 is used as the input voltage to the _VDD terminal in this embodiment. Similarly to the above, the regulated voltage V _R adjusted by the regulated circuit 8 is used.

According to the above configuration, the developing bias circuit 4
-3, a signal from the control circuit 3-3 arranged at a relatively distant position is sent as a digital signal (also referred to as a digital modulation signal), so that the developing bias circuit 4 is not affected by analog external noise. -3, which suppresses the oscillation of the developing bias output, which has been conventionally caused by sending the control signal to the analog signal, and also inputs V _{DD of the} D / A converter (demodulation means) 12. The development bias output accuracy can be improved by setting the input voltage of the above as the regulated voltage V _R from the regulator circuit 8 similarly to the reference voltage of the input voltage of the error amplifier 9 for the development bias output control.

The control signal is binary,
Any of multiple values may be used, and an appropriate digital modulation method can be used.

(Embodiment 3) The present invention uses a PWM (pulse width modulation) signal as a control signal. Although the overall configuration is the same as that of the first embodiment, since the PWM signal is used, the description will be made assuming that the control circuit has the reference numeral 3-4 and the developing bias circuit has the reference numeral 4-4.

FIG. 4 is a circuit diagram of the developing bias circuit 4-4 used in this embodiment.

In this embodiment, the control signal is transmitted from the control circuit 3-4 as a PWM signal, and the developing bias circuit 4-4 which receives the control signal sends this PWM signal from the regulator circuit 8 as shown in FIG. Of the regulated voltage V _R as the amplitude reference (a value obtained by dividing V _R may be used), that is, an amplifying circuit 13 for amplifying until the output is sufficiently saturated with V _R as the power supply voltage (in the figure, the pulse width is It is received by (inversion) and integrated by an integrating circuit (also referred to as a smoothing circuit) 14 to be an input of the error amplifier 9. 13,
Reference numeral 14 forms a demodulation means for the PWM signal. According to the present embodiment, as in the second embodiment, not only the influence of analog external noise during transmission can be removed, but also
Input accuracy of the control signal to the error amplifier 9, since determined by the voltage V _R as a reference voltage of the amplifier circuit 13, it is possible to improve the accuracy of the developing bias output.
As for the accuracy of the PWM signal, the duty is digitally controlled and output without error, while the fluctuation of vibration due to external noise is removed by the amplification circuit, and the error of frequency is smoothed by the integration circuit 14 by the integration circuit 14. It is absorbed to the extent that it is negligible.

The control signal is PWM
In addition to signals, noise-resistant analog modulation signals,
For example, a frequency modulation signal, a phase modulation signal or the like can be used.

In the above embodiment, the DC component control of the developing bias of the electrophotographic apparatus has been described. However, the present invention is not limited to this, and in the AC component control of the developing bias, and further in the control of a general power source. It can be implemented similarly.

In each of the embodiments, the control circuit is described as using the voltage source, but the present invention is not limited to this, and the present invention is not limited to this.
The same can be applied to a control circuit using a current source.

[0036]

As described above, according to the present invention,
It is possible to provide a high-precision power supply device and a power supply device for an electrophotographic device that are less affected by noise such as fluctuations in the power supply voltage.

Specifically, in the invention according to claim 1, the third aspect
Since the power supply of is arranged in the second power supply, it is possible to supply the control circuit of the second power supply with a voltage and a current with less influence of noise, and to output a highly accurate output from the second power supply with less influence of noise. Obtainable.

According to the second aspect of the present invention, since the power supply for the control circuit of the developing bias power supply is arranged in the developing bias power supply, it is possible to supply the voltage and the current having less influence of noise to the control circuit of the developing bias power supply. It is possible to obtain a highly accurate output from the developing bias power source with less influence of noise, and improve the quality of a copied image or a printed image.

In the third aspect of the invention, since the control signal is a digital modulation signal, in addition to the effect of the second aspect of the invention, the effect of preventing the fluctuation of the developing bias power source output due to the fluctuation of the control signal is obtained. Play.

According to the inventions of claims 4 and 5,
Since the control signal is an analog modulation signal resistant to noise, in addition to the effect of the invention described in claim 2, it is possible to prevent the fluctuation of the developing bias power supply output due to the fluctuation of the control signal. Further, since the control can be performed by a single control signal, the number of types of signals from the control device can be reduced as compared with the invention of claim 3.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of a first embodiment.

FIG. 2 is a circuit diagram of a developing bias circuit used in the first embodiment.

FIG. 3 is a circuit diagram of a developing bias circuit used in the second embodiment.

FIG. 4 is a circuit diagram of a developing bias circuit used in a third embodiment.

FIG. 5 is a block diagram of Conventional Example 1.

FIG. 6 is a block diagram of Conventional Example 2.

[Explanation of symbols]

 1 Commercial power supply 2-3 Power supply circuit 4-2 Development bias circuit 8 Regulation circuit

Claims (5)

[Claims] 1. A first power supply which is supplied with power from a commercial power supply and outputs a constant DC voltage, and a first power supply which is arranged at a position distant from the first power supply and which is supplied with power from the first power supply to obtain a desired output. A power supply device comprising: a second power supply; and a third power supply, which is disposed in the second power supply and is used for a control circuit of the second power supply. 2. A power source which is supplied with power from a commercial power source and outputs a constant DC voltage, and a power source which is arranged at a position distant from this power source,
A power supply device for an electrophotographic apparatus, comprising: a developing bias power supply supplied from the power supply; and a power supply for a control circuit for the developing bias power supply, which is disposed in the developing bias power supply. 3. A power source which is supplied with power from a commercial power source and outputs a constant DC voltage, and a power source which is arranged at a position away from this power source,
A developing bias power source supplied from this power source, a control circuit power source for the developing bias power source, which is arranged in the developing bias power source, and a developing bias power source which is arranged at a position apart from the developing bias power source. A control device for generating a digitally modulated signal for controlling,
A power supply device for an electrophotographic apparatus, comprising: a digital demodulation unit which is disposed in the developing bias power source and which demodulates the digital modulation signal and generates a signal for controlling the developing bias power source. 4. A power source which is supplied with power from a commercial power source and outputs a constant DC voltage, and a power source which is arranged at a position apart from this power source,
A developing bias power source supplied from this power source, a control circuit power source for the developing bias power source, which is arranged in the developing bias power source, and a developing bias power source which is arranged at a position apart from the developing bias power source. A control device for generating a noise-resistant type analog modulation signal for controlling, and a demodulation unit arranged in the developing bias power source for demodulating the analog modulation signal and generating a signal for controlling the developing bias power source are provided. A power supply device for an electrophotographic apparatus, which is characterized in that 5. An analog modulation signal resistant to noise is PWM
5. The signal is a signal, and the demodulation means includes amplification means for amplifying the PWM signal until the output is sufficiently saturated, and smoothing means for smoothing the output of the amplification means. Power supply for electrophotographic devices.