JPH11178208A - High-voltage power supply and electronic photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-voltage power supply capable of preventing the continuance of a high-voltage output exceeding a given period, even if an unexpected controlling trouble disables the high-voltage output to be stopped externally. SOLUTION: A timer circuit 1 begins to measure time, in response to the signal state of the remote signal RM indicating the 'on' state of a high-voltage output. This timer circuit 1 measures time for a predetermined period and generates a time-up signal TU, when the given period elapsed. A switching means 2 relays the remote signal RM to a high-voltage generating means 3 unconditionally as long as the timer circuit 1 is not outputting the time-up signal TU. If the switching means 2 receives the time-up signal TU, it stops relaying the remote signal RM and outputs a signal indicating the 'off' state of the high-voltage output. This makes the high-tension generating means 3 stop its output whatever state the remote signal RM is in.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage power supply used for an electrophotographic copying machine, a printer, and the like, and an electrophotographic apparatus equipped with the high-voltage power supply.

[0002]

2. Description of the Related Art Generally, an electrophotographic apparatus is used to form an image.
High voltage is used for processes such as charging, development, transfer, separation, and static elimination. The high voltage is generated by a high voltage power supply mounted in the electrophotographic apparatus.

In a high-voltage power supply device used in this type of electrophotographic apparatus, the control means in the electrophotographic apparatus controls the timing and period according to the electrophotographic process, and further the output value and the like. That is, the output of the high-voltage power supply is variously controlled according to the control signal from the control means.

[0004]

However, in the above-mentioned conventional electrophotographic apparatus, when an unexpected abnormality such as a runaway of a CPU used as a control means occurs, an abnormal situation in which a high-voltage output of a high-voltage power supply always outputs is obtained. It can be considered. In such a case, since it is impossible to stop the output of the high voltage from the outside, there is a possibility that a device in the electrophotographic apparatus such as a developing device, a transfer charger or a separation charger is seriously damaged.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, the present invention prevents continuation of a high voltage output beyond a predetermined period even when an external high voltage output cannot be stopped due to an unexpected control trouble. It is an object of the present invention to provide a high-voltage power supply device capable of performing the above-described operations and an electrophotographic apparatus equipped with the high-voltage power supply device.

[0006]

In order to achieve the above object, according to a first aspect of the present invention, a high voltage generating means for generating a high voltage output, and a predetermined period from the start of the output of the high voltage output are measured. Timer means for generating a time-up signal when the time has reached, and output stopping means for stopping the high-voltage output of the high-voltage generating means in response to the time-up signal from the timer means.

In a second aspect based on the first aspect, the apparatus has an external input terminal for generating / stopping or controlling a high voltage output by the high voltage generation means, and the timer means is provided with an input to the external input terminal. The measurement for the predetermined period is performed according to the state of the input signal to be input.

In a third aspect based on the second aspect, the stop of the high voltage output by the output stop means is performed independently of the state of the input signal input to the external input terminal. Is switched to the output stop state.

In a fourth aspect based on the first aspect, there is provided an output detecting means for detecting an output state of the high voltage generating means, and the timer means is provided based on the detection of the high voltage output by the output detecting means. Thus, the measurement for the predetermined period is performed.

In a fifth aspect based on the first or fourth aspect, the output stop means reduces or stops power supply to the high voltage generation means in response to the time-up signal from the timer means. It was made.

In a sixth aspect based on the first to fifth aspects, the time-up signal is taken out to the outside.

According to a seventh aspect of the present invention, there is provided a high-voltage power supply for generating and outputting a high voltage, and control means for outputting a control signal for controlling the high-voltage power supply. As an operating voltage, in an electrophotographic apparatus that performs image formation by an electrophotographic method, the high-voltage power supply includes:
High-voltage generating means for generating a high-voltage output, timer means for measuring a predetermined period from the start of output of the high-voltage output, and generating a time-up signal when the predetermined period has been reached; and Output stop means for receiving the high pressure output of the high pressure generating means.

In an eighth aspect based on the seventh aspect, the high-voltage power supply device has an input terminal for emitting / stopping or controlling a high-voltage output by the high-voltage generating means, and is supplied to the input terminal. The timer measures the predetermined period according to the state of the control signal.

In a ninth aspect based on the eighth aspect, the stopping of the high voltage output by the output stopping means of the high voltage power supply device is performed independently of a state of a control signal input to the input terminal. Is switched to the output stop state.

In a tenth aspect based on the ninth aspect, the high-voltage power supply has output detection means for detecting an output state of the high-voltage generation means, and the high-voltage output is detected by the output detection means. The predetermined time period is measured by the timer means.

In an eleventh aspect based on the tenth aspect, the output stopping means of the high-voltage power supply device receives the time-up signal from the timer means to reduce or stop power supply to the high-voltage generating means. The configuration is as follows.

According to a twelfth aspect, in the seventh to eleventh aspects, the power supply of the device is stopped by the time-up signal taken from the high voltage power supply device.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing a schematic configuration of a high-voltage power supply according to a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a timer circuit, which measures a time in response to a remote signal RM input from the outside, and when a predetermined period is reached, a time-up signal TU indicating that the period has elapsed. Is output. Reference numeral 2 denotes switch means for interrupting the relay of the remote signal RM in response to the time-up signal TU. Reference numeral 3 denotes a high voltage generating means for generating / stopping a high voltage output according to a remote signal RM from the switch means 2.

With the above configuration, the high-voltage power supply of this embodiment performs the following operation.

First, the high voltage output is turned on / off by the remote signal RM. At this time, the timer circuit 1
The time measurement is started in response to the signal state of the remote signal RM indicating the high voltage output ON (at the time of occurrence). This timer circuit 1
Measures a predetermined period and generates a time-up signal TU indicating that when the predetermined period is reached.

On the other hand, when the timer circuit 1 is not outputting the time-up signal TU, the switch means 2 relays the remote signal RM to the high voltage generation means 3 unconditionally. Therefore, the high voltage generation means 3 outputs the high voltage output ON when the remote signal RM is turned on.
Is indicated, the control according to it is started to generate a high-voltage output, and when the high-voltage output is OFF (when stopped), the high-voltage output is stopped in the same manner.

When the time-up signal TU from the timer circuit 1 is input to the switch means 2, the switch means 2 stops relaying the remote signal RM, and outputs a signal indicating the high voltage output OFF to any of the remote signals RM. Output regardless of status. As a result, the high-pressure generating means 3 is controlled so that the output is stopped in any state of the remote signal RM.

FIG. 2 is a detailed circuit diagram of the timer circuit 1 and the switch means 2.

FIG. 3 shows an example in which the high-voltage output is ON when the remote signal RM is at "H" level, and the high-voltage output is OFF when the remote signal RM is at "L" level.

In the figure, when the remote signal RM becomes "H" level of about 5 V, the transistor Tr with a built-in resistor
21 is turned on, and the transistor Tr22 is turned off. As a result, the plus terminal of the comparator COMP is connected to the power supply voltage Vs, the resistor R23 and the capacitor C2.
A voltage is applied by a charging circuit consisting of 1s. This voltage rises according to the time constant consisting of the resistor R23 and the capacitor C21, and this voltage
When the voltage reaches the reference voltage Vref input to the terminal, the output of the comparator COMP changes from “L” level output to “H”.
Changes to level output.

In the example of the present circuit, an example in which an open collector output comparator is used for the comparator COMP is shown. Therefore, the output at the "H" level has a high impedance. As a result, the output of the comparator COMP becomes the Zener voltage of the Zener diode ZD21. If this Zener voltage is selected, for example, to 5V, a 5V time-up signal TU can be obtained.

On the other hand, the time-up signal TU is input to the base of the transistor Tr23, so that the transistor Tr23 is turned on.
, The relay signal RE which has indicated the “H” level is switched to the “L” level.

By the way, if the remote signal RM switches to the off state (that is, "L" level) before the input of the plus terminal of the comparator COMP reaches the reference voltage Vref, the transistor Tr21 turns off and the transistor Tr22 turns on. Become. As a result, the comparator CO
Since the plus terminal voltage of MP remains at the “L” level and does not reach the reference voltage Vref, the time-up signal TU is not output.

As described above, the power supply voltage Vs, the resistance R23,
In the timer circuit 1 including the capacitor C21 and the reference voltage Vref, if a time longer than a predetermined high-voltage output ON period in the electrophotographic process is set as a measurement constant, an abnormality occurs in the control circuit that generates the remote signal RM. If this occurs, runaway of the high-voltage output can be avoided beforehand.

As shown in FIG. 2, if the time-up signal TU is taken out to the outside, the control can be performed by utilizing the time-up signal TU as a power stop signal (shutdown) of the electrophotographic apparatus. Safety at the time of abnormality can be greatly improved.

(Second Embodiment) FIG. 3 is a block diagram showing a schematic configuration of a high-voltage power supply according to a second embodiment of the present invention.

The high voltage generating means 3a shown in FIG. 3 has an output terminal for a detection signal KS for detecting the high voltage output, in addition to the high voltage output controlled by turning on / off the remote signal RM (H / L). The timer circuit 1a outputs the detection signal K
It is configured to start time measurement in response to S. As a result, the timer circuit 1 a
Since the time is measured in conjunction with the period during which a is generating a high voltage, the high voltage output period can be measured directly.

FIG. 4 is a circuit diagram showing a configuration example of the high voltage generating means 3a in FIG.

In the figure, reference numeral 41 denotes a high voltage control means which is turned on / off by a remote signal RM or a relay signal RE.
Upon receiving the OFF signal, the transformer T41 is driven and controlled. The transformer T41 has a primary winding, a high-voltage winding, and a detection winding driven by the high-voltage control means 41 to generate a high-voltage output HV and a detection signal KS. D41 is
This is a diode for rectifying the output from the detection winding. The capacitor C41 is a capacitor for smoothing the rectified output from the diode D41, R41 and R42 are resistors, and ZD41 is a Zener diode.

With the above configuration, the high-pressure control means 41
Drives the transformer T41 in response to the ON state of the remote signal RM or the relay signal RE, and generates a high voltage output HV. At this time, the high voltage output H is also applied to the detection winding of the transformer T41.
A signal linked to V is generated, and this signal is
The detection signal KS is obtained by rectifying and smoothing the signal with 1 and the capacitor C41.

FIG. 5 is a circuit diagram showing a configuration example of the timer circuit 1a in FIG.

This timer circuit 1a is a timer circuit having a latch-up function, in which a transistor Tr51 for output latch and a transistor Tr52 for resetting latch output are added to the timer circuit (FIG. 2) shown in the first embodiment. It is.

According to this circuit, when the time-up signal TU switches to the "H" level after the elapse of the predetermined period, the transistor Tr51 is turned on by the time-up signal TU. Thereby, the transistor Tr22
Maintains the off-state in any state of the remote signal RM. As a result, the voltage of the plus input terminal of the comparator COMP maintains the charging voltage characteristic by the resistor R23, the capacitor C21, and the power supply voltage Vs. That is,
Once the voltage at the plus terminal reaches the reference voltage Vref and the output of the comparator COMP goes to the “H” level, the comparator COMP maintains the “H” level.

On the other hand, when "H" level is input as the reset signal RS to the base terminal of the transistor Tr52, the transistor Tr52 is turned on, and the positive terminal voltage of the comparator COMP is forcibly discharged.
As a result, the voltage of the plus terminal falls below the reference voltage Vref applied to the minus terminal, and the output of the comparator COMP changes to the “L” level state. Thereafter, when the reset signal RS is set to the “L” level and the transistor Tr52 is turned off, the timer circuit 1
a becomes a startable state.

This timer circuit with latch-up function 1a
According to this, the stop of the high voltage output HV can be maintained for a desired period.

(Third Embodiment) FIG. 6 is a block diagram showing a schematic configuration of a high-voltage power supply according to a third embodiment of the present invention. Elements common to FIG. 3 are denoted by the same reference numerals. I have.

The high-voltage power supply device of this embodiment is different from the second embodiment in that a high-voltage stop circuit 4 is provided instead of the switch means 2 as a method of stopping high-voltage output. Of the transformer T41 is stopped. FIG. 7 is a circuit diagram showing the configuration of the high-voltage stopping circuit 4 and the high-voltage generating means 3b in FIG.

In the figure, reference numeral 61 denotes control means for generating a pulse signal for controlling the transformer T41. The transistor Tr61 drives the transformer T41 in accordance with the control means 61.
r62 is a transistor for interrupting power supply to the transformer T41. Transistors Tr63 and Tr64 are transistors for controlling the transistor Tr62, R61 to R64 are resistors, C61
Is a capacitor.

In the above configuration, when an ON signal of the remote signal RM (a signal instructing to turn on the high voltage output) is input to the control means 61, the control means 61 generates a pulse signal for performing predetermined control. Transistor Tr61
Performs the on / off operation in response to the pulse signal, and the transformer T41 is driven by the power supplied through the resistor R61 and the transistor Tr62 by turning on / off the transistor Tr61, and outputs the high voltage output HV and the detection signal. Generate KS.

In this state, when the time-up signal TU is output to the "H" level from the timer circuit 1a, the transistor Tr64 is turned on, and the transistor T64 is turned on.
r63 is turned off. As a result, the transistor Tr62 is turned off. That is, the power supply to the transformer T41 is cut off, and the high voltage output HV and the detection signal KS of the transformer T41 are stopped.

FIG. 8 is a schematic sectional view showing the structure of an electrophotographic apparatus (copier) equipped with the high-voltage power supply of the present invention.

This copying machine is equipped with the high-voltage power supply device 300 realized in the above embodiment. The output state of the high-voltage power supply device 300 is controlled in accordance with a control signal from a controller 310 that performs various controls for performing image formation in an electrophotographic process. Upon receiving the high voltage generated by the high-voltage power supply device 300, the primary charger 106, the developing device 109, the transfer charger 110, and the separation charger 111 of the copying machine perform predetermined operations.

First, in FIG. 8, reference numeral 100 denotes a copying machine main body, 200 denotes a circulating automatic document feeder for automatically feeding a document, ie, a feeder (hereinafter referred to as RDF), and 250 denotes a sorter, ie, a sorter. The RDF 200 and the sorter 250 can be freely used in combination with the main body 100.

Reference numeral 101 denotes an original table glass as an original mounting table. Reference numeral 102 denotes an optical system as an image reading unit, which includes an original illumination lamp (exposure lamp) 103, a scanning mirror, a lens 143, a motor 104, and the like.
At 03, the original is illuminated, and reflected light from the original is irradiated on the photosensitive drum 105 by a scanning mirror and a lens.

Around the photosensitive drum 105, a primary charger 106, a blank exposure unit 107, a potential sensor 108, a developing device 109, a transfer charger 110,
A separation charger 111 is provided, and the photosensitive drum 105 and the like constitute an image forming unit.

The photosensitive drum 105 is connected to the main motor 11
3 rotates in the direction of the arrow shown in FIG. 8 and is corona-charged by the primary charger 106.
When the reflected light from the document 2 is emitted from 2, an electrostatic latent image is formed. This electrostatic latent image is developed by the developing device 109 and is visualized as a toner image.

On the other hand, the transfer paper sent from the upper cassette 114 or the lower cassette 115 to the main body 100 by the paper feeding rollers 118 and 119 via the pickup rollers 116 and 117 is transferred to the registration roller 120 by the registration roller 120 so that the leading end of the toner image is After the timing is set so that the leading edge of the toner image coincides with the leading edge of the photosensitive drum 105, the toner image is transferred to the photosensitive drum 105, and the toner image is transferred by the transfer charger 110. After this transfer,
The transfer paper is separated from the photosensitive drum 106 by the separation charger 111, guided to the fixing device 122 by the conveyor belt 121, fixed by pressure and heat, and then discharged out of the main body 100 by the discharge roller 123. .

[0055]

As described in detail above, according to the high-voltage power supply device of the first invention, a high-voltage generating means for generating a high-voltage output, and measuring a predetermined period from the start of the output of the high-voltage output,
A timer means for generating a time-up signal when the predetermined period has been reached, and output stop means for stopping the high-voltage output of the high-voltage generating means in response to the time-up signal from the timer means, include Even if it is impossible to control the high voltage output from the outside due to control problems that cannot be obtained, it is possible to prevent the continuation of the high voltage output beyond a predetermined period, and the danger caused by the abnormal situation where the high voltage output is constantly output Can be avoided beforehand.

According to the high voltage power supply of the second invention,
In the first aspect, the apparatus has an external input terminal for emitting / stopping or controlling a high voltage output by the high voltage generating means,
The timer means is configured to start measuring the predetermined period in accordance with the state of the input signal input to the external input terminal. Therefore, the effect of the first invention can be obtained with a simple configuration.

According to the high voltage power supply of the third invention,
In the second invention, the stop of the high voltage output by the output stop means is performed by switching a signal state of the external input terminal to an output stop state regardless of a state of an input signal input to the external input terminal. Things. Therefore,
With the simple configuration, the effects of the first invention can be obtained.

According to the high voltage power supply of the fourth invention,
In the above-mentioned first invention, a configuration is provided in which output detection means for detecting an output state of the high voltage generation means, and wherein the timer means starts measurement of the predetermined period when the output detection means detects the high voltage output. Accordingly, the high voltage output and the timer measurement can be linked, and the high voltage output period can be measured more reliably.

According to the high voltage power supply of the fifth invention,
In the first or fourth aspect of the invention, the output stopping means is configured to reduce or stop the power supply to the high voltage generating means in response to the time-up signal from the timer means. Can be stopped.

According to the high voltage power supply of the sixth invention,
In the first to fifth aspects of the present invention, since the time-up signal is configured to be taken out to the outside, it is possible to perform a treatment on an external device (for example, an electrophotographic device) side and to perform more reliable danger avoidance. it can.

According to the electrophotographic apparatus of the seventh invention,
An effect equivalent to that of the first aspect is provided.

According to the electrophotographic apparatus of the eighth invention,
According to the seventh aspect, the same effects as those of the second aspect are exerted.

According to the electrophotographic apparatus of the ninth aspect,
In the eighth aspect, an effect equivalent to that of the third aspect is provided.

According to the electrophotographic apparatus of the tenth aspect, the same effects as those of the fourth aspect can be obtained in the ninth aspect.

According to the electrophotographic apparatus of the eleventh aspect, the same effects as those of the fifth aspect can be obtained in the tenth aspect.

According to the electrophotographic apparatus of the twelfth aspect, the seventh to eleventh aspects have the same effects as the sixth aspect.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a high-voltage power supply according to a first embodiment of the present invention.

FIG. 2 is a detailed circuit diagram of a timer circuit 1 and a switch means 2 in FIG.

FIG. 3 is a block diagram illustrating a schematic configuration of a high-voltage power supply device according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a configuration example of a high-voltage generating means 3a in FIG.

FIG. 5 is a circuit diagram showing a configuration example of a timer circuit 1a in FIG. 3;

FIG. 6 is a block diagram illustrating a schematic configuration of a high-voltage power supply according to a third embodiment of the present invention.

FIG. 7 is a diagram showing a high-pressure stop circuit 4 and a high-pressure generating means 3b in FIG.
FIG. 3 is a circuit diagram showing the configuration of FIG.

FIG. 8 is a schematic sectional view showing the structure of an electrophotographic apparatus (copier) equipped with the high-voltage power supply of the present invention.

[Explanation of symbols]

 1, 1a Timer circuit 2 Switching means 3, 3a, 3b High voltage generating means 4 High voltage stop circuit RM Remote signal TU Time up signal KS detection signal RS Reset signal

Claims (12)

[Claims] A high-voltage generating means for generating a high-voltage output; a timer means for measuring a predetermined period from the start of the output of the high-voltage output, and generating a time-up signal when the predetermined period has been reached; An output stopping means for stopping a high voltage output of the high voltage generating means in response to a time-up signal. 2. A high voltage output by the high voltage generating means is generated.
2. The apparatus according to claim 1, further comprising an external input terminal for stopping or controlling, wherein the timer means measures the predetermined period according to a state of an input signal input to the external input terminal. High voltage power supply. 3. The high voltage output is stopped by the output stop means by switching a signal state of the external input terminal to an output stop state irrespective of a state of an input signal input to the external input terminal. 3. The high-voltage power supply according to claim 2, wherein: 4. An output detecting means for detecting an output state of the high voltage generating means, wherein the timer means measures the predetermined period based on detection of the high voltage output by the output detecting means. The high-voltage power supply device according to claim 1, wherein: 5. The apparatus according to claim 1, wherein said output stop means receives or receives said time-up signal from said timer means, and reduces or stops power supply to said high voltage generation means. A high-voltage power supply as described. 6. The high-voltage power supply device according to claim 1, wherein the time-up signal is taken out. 7. A high-voltage power supply for generating and outputting a high voltage, and control means for outputting a control signal for controlling the high-voltage power supply, wherein the high voltage generated by the high-voltage power supply is used as an operating voltage. In an electrophotographic apparatus that forms an image by an electrophotographic method, the high-voltage power supply unit includes a high-voltage generating unit that generates a high-voltage output, and measures a predetermined period from the start of the output of the high-voltage output, and a time when the predetermined period is reached. An electrophotographic apparatus comprising: timer means for generating an up signal; and output stopping means for stopping the high voltage output of the high voltage generating means in response to the time-up signal from the timer means. 8. The high-voltage power supply device has an input terminal for emitting / stopping or controlling a high-voltage output by the high-voltage generating means, and the timer controls the predetermined voltage by the state of a control signal input to the input terminal. The electrophotographic apparatus according to claim 7, wherein the apparatus is configured to measure a period. 9. The stop of the high voltage output by the output stop means of the high voltage power supply device is performed by switching the signal state of the input terminal to the output stop state irrespective of the state of the control signal input to the input terminal. 9. The electrophotographic apparatus according to claim 8, wherein the step is performed. 10. The high-voltage power supply device has output detection means for detecting an output state of the high-voltage generation means, and measures the predetermined period by the timer means when the high-voltage output is detected by the output detection means. The electrophotographic apparatus according to claim 9, wherein the apparatus is configured to perform the following. 11. The output stopping means of the high-voltage power supply device is configured to reduce or stop power supply to the high-voltage generating means in response to the time-up signal from the timer means. An electrophotographic apparatus according to claim 7 or claim 10. 12. The electrophotographic apparatus according to claim 7, wherein the power supply of the apparatus is stopped by the time-up signal taken out from the high-voltage power supply apparatus.