JPH06217458A - High voltage power supply for corona discharge - Google Patents

Abstract

PURPOSE:To prevent erroneous function due to noise and unwanted generation of ozone when a high voltage power supply produces output erroneously upon turn ON or turn OFF of an electrophotographic unit. CONSTITUTION:The high voltage power supply for corona discharge comprises a boosting means 4 connected with a DC power supply, a switching means 5, means 3 for detecting output voltage or current level, and means 2 for controlling the switching to obtain a predetermined detection level. The high voltage power supply further comprises means 1 for detecting the input voltage level, and means 6-9 for stopping the operation of the power supply circuit depending on the voltage level detected by the input level detecting means 1.

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 corona discharge of an electrophotographic apparatus.

[0002]

2. Description of the Related Art A high-voltage power supply device of this type is disclosed in Japanese Unexamined Patent Publication No. 60-257772 and Japanese Utility Model Laid-Open No. 61-.
126258, JP-A-62-42217,
JP-A-2-68569, JP-A-2-228250
Japanese Laid-Open Patent Publication No. 63-95852 and Japanese Utility Model Publication No. 1-1.
The one disclosed in Japanese Patent No. 34988 is known.

Among them, the technique disclosed in Japanese Patent Laid-Open No. 60-257772 receives a DC voltage from a DC power source and outputs a high voltage to a corona discharger by a trigger signal from a control unit. In addition, the actual development Sho 61-1262
The technique disclosed in Japanese Patent Laid-Open No. 58-58 is one in which when the power supply voltage drops, the paper is forcibly discharged and then the power supply is turned off. Further, the technology disclosed in Japanese Patent Laid-Open No. 62-42217 is such that a reset signal is output when the power supply voltage drops. Further, the technique disclosed in Japanese Patent Laid-Open No. 2-68569 includes a relay so that a voltage is not applied when the input voltage is higher than a predetermined value in order to protect the input power supply when a power supply with a wrong rating is turned on. It is a thing.
Further, the technology disclosed in Japanese Patent Laid-Open No. 2-228250 relates to a protection means against abnormalities in high voltage output. Furthermore, JP-A-63-95852 and Japanese Utility Model Publication 1-1
The technology disclosed in Japanese Laid-Open Patent Publication No. 34988 discloses that the microcomputer is configured such that the input voltage of the high voltage power source is raised after the input power source of the microcomputer is raised and the input voltage of the high voltage power source is lowered and then the input voltage of the microcomputer is lowered. The input voltage of the high voltage power supply is not supplied in the unstable state.

[0004]

In this type of power supply device, many techniques have been proposed as described above, but there are still insufficient points in the following points.

That is, if external noise is received when the power supply voltage of the microcomputer is unstable, the program may run out of control and cause a fatal malfunction. Specifically, when the DC power supply voltage immediately after the power switch of the electrophotographic device is turned on or off is unstable and high voltage is generated from the high voltage power supply to generate noise, the microcomputer runs away and causes a fatal malfunction. . It is impossible to prevent the high-voltage power supply from erroneously outputting so that a fatal problem immediately after turning on / off the power does not occur.

Also, an output for the control unit of the DC power supply,
Controls the rise and fall timing of the output for high-voltage power supply, and when the microcomputer is in an unstable state,
A complicated structure is required to control the output timing of the DC power supply so as not to supply the DC power supply to the high-voltage power supply, and it cannot be used in a device that requires high reliability, downsizing, and low cost.

Further, although it is relatively easy to lower the input voltage of the high-voltage power supply first by the program of the microcomputer, the input AC power of the DC power supply, that is, the microcomputer when the power switch of the electrophotographic apparatus is turned off. The input voltage of must be maintained longer than the input voltage of the high voltage power supply, and the design of the DC power supply cannot be done unless the load conditions connected to the DC power supply are determined. It is extremely difficult to completely control each output timing of the DC power supply until the power switch is turned on and off in a short time.

In addition, if the high-voltage power supply itself outputs a high voltage when the input power supply rises or falls, even if there is no malfunction of the microcomputer, the deterioration of the photoconductor and the generation of unnecessary ozone are slightly caused. There was a problem.

The present invention has been made in view of such a background, and an object thereof is that the high-voltage power supply erroneously outputs when the power of the electrophotographic apparatus is turned on or off, and the apparatus malfunctions due to noise at this time. It is an object of the present invention to provide a high voltage power supply for corona discharge that does not cause the problem of unnecessary ozone generation.

[0010]

Means for Solving the Problems The above object is to provide a boosting means and a switching means connected to a DC power supply, an output level detecting means for detecting an output voltage or a current, and a detection value detected by the output level detecting means. In a high voltage power supply for corona discharge of an electrophotographic apparatus provided with a switching control means for controlling the switching means so as to have a predetermined size, an input level detection means for detecting a level of an input voltage, and the input level detection means This is achieved by the first means including stop control means for stopping the operation of the power supply circuit according to the detected voltage detected.

Further, in a high voltage power supply for corona discharge on the same assumption, according to a time detecting means for detecting an elapsed time from turning on or off of an input voltage, and a detecting time detected by the time detecting means. This is also achieved by the second means having stop control means for stopping the operation of the power supply circuit.

Further, in place of the stop control means in the first means, there is provided power supply output control means for performing either operation of opening or short-circuiting the power supply output in accordance with the detection voltage detected by the input level detection means. It is also achieved by the third means.

Further, in place of the stop control means in the second means, there is provided a power supply output control means for performing either operation of opening or short-circuiting the power supply output in accordance with the detection time detected by the time detection means. It is also achieved by the means of 4.

Further, the stop control means in the first and second means may be constituted by a switch means for cutting off the input power supply line, a switch means for cutting off the trigger signal line, a switch means for cutting off the driving of the switching element, and the like. it can.

The time detecting means in the second means may be composed of means for charging / discharging the input voltage and means for detecting the charging / discharging level. The time for stopping the operation of the power supply circuit after the input of the input voltage is It is desirable to set the time longer than the time from when the input voltage is cut to when the operation of the power supply circuit is stopped.

[0016]

In the first means, the operation of the power supply circuit is stopped in accordance with the detection result of the input voltage. In the second means, the power supply is turned on or off according to the time from turning on or off the input voltage. By stopping the operation of the circuit, each unnecessary output is prevented.

In the third means, the power supply output is opened or short-circuited according to the detection result of the input voltage. In the fourth means, the power supply is turned on or off according to the time after the input voltage is turned on or off. By opening or shorting the output,
I try not to put out unnecessary output respectively.

[0018]

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

FIG. 1 is a circuit diagram of a high voltage power supply for corona discharge according to an embodiment.

In FIG. 1, A and C are input terminals of a DC power source, and B is a trigger input terminal for instructing on / off of output. Further, 1 is input detection means (input detection section), 2 is switching control means (switching control section), 3 is output detection means (output detection section), 4 is boosting means (step-up transformer), 5 is switching means (switching). element),
6, 7, 8, 9 are switches for stopping circuit operation, 10, 11
Is an output stop switch, and D and E are output terminals.

In the circuit thus constructed, the primary winding of the boosting means 4 and the switching means 5 connected to the DC power supply are switched by the switching control means 2 to obtain a high voltage on the secondary side of the boosting means 4. . The high voltage output is detected by the output detection means 3 and fed back to the switching control means 2. In this case, the switching condition is determined so that the output has a predetermined value. The details of the switching type high-voltage power supply are disclosed in Japanese Patent Laid-Open No. 60-257772, etc., and are known techniques, so the description thereof is omitted here.

The input detecting means 1 is an input terminal A of the DC power source,
It is connected between C and detects the level of the input voltage in the first embodiment, and when it reaches a predetermined level, the switch 6 to
It is a means for outputting a signal for switching 9 and 10, 11 and, in the second embodiment, a signal for switching the switching means when the time from turning on or off the DC power supply is detected and a predetermined time has passed. Is a means of issuing.

FIG. 2 is a graph in which the vertical axis represents the input voltage Vin and the horizontal axis represents the elapsed time t. Depending on the circuit configuration of the switching control means 2, a high voltage is output when the input voltage is V1. Therefore, it is necessary to stop the circuit operation or the power supply output when the input voltage is V2 or less. For this purpose, the level V2 of the input voltage is directly detected or the elapsed times T1 and T2 corresponding thereto are detected, and the switch 6 for turning off the input of the boosting means 4 or the switching control so that the power supply circuit does not operate. The switch 8 for turning off the power input of the means 2, the switch 9 for turning off the drive signal of the switching means 5, or the switch 10 for opening the power output or the switch 11 for shorting the power output is switched so as not to output the output.

A false trigger signal may be output from the control unit to the high-voltage power supply when the DC power supply supplied to the control unit that generates the output timing signal of the high-voltage power supply rises and falls. Generally, 5V is used for the control unit and 24V for the high voltage power supply.
V is supplied. Therefore, if the 24V power supply is turned on after the false trigger signal disappears, no problem appears. For this purpose, it is necessary to control the rising and falling timings of the 5V power supply and the 24V power supply, but there is a problem that the circuit is complicated and the cost is increased. To be done.

Therefore, a protection circuit against a false trigger is provided in the high voltage power supply. That is, this is configured by switching the switch 7 for cutting off the trigger signal in FIG. 1 by the input detection means 1. Since the rising and falling timings of 5V and 24V are fixed once the device is decided, 2
It is easy to detect the time when the false trigger signal is generated from the rise and fall of the 4V power supply.

In FIG. 1, the means for stopping the power supply operation (circuit operation stop switches 6, 7, 8, 9) or the means for stopping the output (output stop switches 10, 11) is provided on one circuit. Although incorporated, it is obvious that any one means can be used if the control method is determined.

FIG. 3 shows a concrete circuit example of the input detecting means (input voltage detecting means) 1 in FIG. 1, in which the voltage between the input power supply terminals A and C is divided by the resistors R1 and R2, and the level is obtained by the zener diode ZD1. To drive the transistor Q1.

FIG. 4 is a concrete circuit example of the input detecting means (time detecting means from turning on or off of the input voltage) in FIG. 1, and R3 and C connected between the input power supply terminals A and C.
1 and R4, and a transistor Q2 driven by the charge / discharge circuit.

As described above, according to the above-described embodiment, since the high-voltage power supply itself detects the input voltage, even if the control power supply and the high-voltage power supply are different from each other, the high-voltage power supply can be reliably operated when the input voltage rises and falls. Malfunctions can be eliminated. Further, since the input line of the trigger signal is cut off, even if there is an erroneous trigger from the control unit, it is possible to prevent the high voltage output. Furthermore, since a large and expensive control circuit for controlling the rising and falling of the control power supply and the other power supply for the load is not required, it is possible to provide a small and low-priced electrophotographic apparatus.

[0030]

As described above, the present invention has the following effects.

That is, according to the invention of claim 1,
Since the operation of the power supply circuit is stopped according to the detection voltage detected by the input level detection means, even if the power supply for control and the power supply for high-voltage power supply are different, it is possible to reliably eliminate malfunctions when the input voltage rises and falls. be able to. Further, since high voltage is not output when the input power source rises or falls, generation of unnecessary ozone can be prevented.

According to the invention described in claims 2, 8 and 9, since the operation of the power supply circuit is stopped in accordance with the detection time detected by the detecting means, the same effect as the invention described in claim 1 can be obtained. .

According to the third aspect of the invention, the operation of opening or short-circuiting the power supply output is performed according to the detection voltage detected by the input level detecting means.
The same effect as that of the first aspect of the invention is achieved.

According to the invention described in claim 4, either the opening or the short-circuiting of the power supply output is performed according to the detection time detected by the time detecting means.
The same effect as the described invention is achieved.

According to the invention described in claim 5, since the power supply output is opened by cutting off the input power supply line, the same effect as the invention described in claim 1 can be obtained.

According to the sixth aspect of the present invention, since the trigger signal line is cut by the switch means, even if there is an erroneous trigger from the control section, it is possible to prevent the high voltage output. Further, since high pressure output can be omitted, unnecessary ozone can be prevented from being generated.

According to the seventh aspect of the invention, the switch means cuts off the driving of the switching element and stops the operation of the power supply circuit. Therefore, the same effect as that of the first aspect of the invention can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a high voltage power supply for corona discharge according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a detection level or a detection time of an input voltage according to an embodiment of the present invention.

FIG. 3 is a circuit diagram showing a first embodiment of the input detection means shown in FIG.

FIG. 4 is a circuit diagram showing a second embodiment of the input detection means shown in FIG.

[Explanation of symbols]

 1 Input Detection Means 2 Switching Control Means 3 Output Detection Means 4 Boosting Means 5 Switching Means 6-9 Circuit Operation Stop Switches 10, 11 Output Stop Switches

Claims (9)

[Claims] 1. A boosting means and a switching means connected to a DC power source, an output level detecting means for detecting an output voltage or a current, and a detection value detected by the output level detecting means having a predetermined magnitude. In a high voltage power supply for corona discharge of an electrophotographic apparatus equipped with a switching control means for controlling a switching means, an input level detecting means for detecting a level of an input voltage and a detection voltage detected by the input level detecting means A high voltage power supply for corona discharge, comprising: stop control means for stopping the operation of the power supply circuit. 2. A boosting means and a switching means connected to a DC power source, an output level detecting means for detecting an output voltage or a current, and a detection value detected by the output level detecting means having a predetermined magnitude. In a high voltage power supply for corona discharge of an electrophotographic apparatus provided with a switching control means for controlling a switching means, a time detection means for detecting an elapsed time from either turning on or off of an input voltage, and detection by this time detection means A high voltage power supply for corona discharge, comprising: stop control means for stopping the operation of the power supply circuit in accordance with the detected time. 3. A boosting means and a switching means connected to a DC power supply, an output level detecting means for detecting an output voltage or a current, and a detection value detected by the output level detecting means having a predetermined magnitude. In a high voltage power supply for corona discharge of an electrophotographic apparatus provided with a switching control means for controlling a switching means, an input level detecting means for detecting a level of an input voltage and a detection voltage detected by the input level detecting means A high voltage power supply for corona discharge, comprising: a power supply output control means for performing either an open or a short circuit of the power supply output. 4. A boosting means and a switching means connected to a DC power source, an output level detecting means for detecting an output voltage or a current, and a detection value detected by the output level detecting means having a predetermined magnitude. In a high voltage power supply for corona discharge of an electrophotographic apparatus equipped with a switching control means for controlling a switching means, a time detecting means for detecting a time from turning on or off of an input voltage and a time detecting means for detecting the time. Depending on the detection time,
A high voltage power supply for corona discharge, comprising: a power supply output control means for opening or shorting the power supply output. 5. The high voltage power supply for corona discharge according to claim 1 or 2, wherein the stop control means is a switch means for disconnecting an input power supply line. 6. The high voltage power supply for corona discharge according to claim 1, wherein the stop control means is a switch means for disconnecting a trigger signal line. 7. The high voltage power supply for corona discharge according to claim 1, wherein the stop control means is a switch means for cutting off the driving of the switching element. 8. The high voltage power supply for corona discharge according to claim 2, wherein the time detecting means comprises means for charging / discharging an input voltage and means for detecting a charge / discharge level. 9. The corona discharge according to claim 2, wherein the time from turning on the input voltage to stopping the operation of the power supply circuit is set longer than the time from turning off the input voltage to stopping the operation of the power supply circuit. High voltage power supply.