JPH06348116A - Corotron leak detecting device - Google Patents

Abstract

PURPOSE:To detect the abnormal state of corotrons by providing corotron output drop detecting circuits in corotron output control circuits applying high voltage to a plurality of corotrons arranged on a photoreceptor drum, and inputting the leak information detected by the detecting circuits to a control device. CONSTITUTION:Various corotrons 20, 21, 22, 23 are arranged on the periphery of a photoreceptor drum, and corotron output control circuits 25-25c are arranged for the corotrons 20-23. Output drop detecting circuits 26-26c are provided in the corotron output control circuit 25-25c to detect leaks. The fail signals outputted from the output drop detecting circuits 26-26c are inputted to a control device 29. The length of the leak occurrence time, occurrence interval, and the number of leaks are detected in the control device 29, and the abnormal state of corotron wires is detected. Generation of defective copies is detected, and copies are again produced when defective copies are produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for forming a toner image using an electrophotographic system such as an electrophotographic copying machine, for detecting an abnormality of a corotron, and in particular, an abnormal discharge occurs in the corotron. The present invention relates to a corotron leak detection device that detects a state by using a corotron output droop detection circuit provided in a power supply device and detects a failure based on information such as the number of abnormal discharges and time intervals.

[0002]

2. Description of the Related Art Like electrophotographic copying machines and printers,
In an image forming apparatus that forms a toner image on a photoconductor such as a photoconductor drum by using an electrophotographic method, a plurality of discharge devices such as a charging corotron and a transfer / peeling corotron are arranged around the photoconductor drum. There is. Among the corotron devices, the charging corotron is a photosensitive drum by uniformly charging the surface of the photosensitive drum and irradiating it with light of an image obtained by scanning an original, or by writing with a laser beam. Allow the drum to form an electrostatic latent image.
In addition, a pre-transfer corotron is arranged immediately in front of the image transfer portion of the photosensitive drum so as to weaken the adhesive force of the toner to the surface of the photosensitive drum. Further, the transfer / peeling corotron arranged in the image transfer portion of the photoconductor drum is used to perform the action of transferring the toner image to the paper and the action of peeling the paper from the photoconductor drum.

In various types of corotrons as described above, a mechanism for generating a discharge between the corotron wire connected to a high voltage power source and a photoconductor drum by applying a high voltage thereto is constructed. . However, if foreign matter adheres to the corotron or if dust or the like that floats inside the image forming apparatus enters, abnormal discharge occurs, and there arises a problem that the charging action or the like on the photosensitive drum is not normally performed. . Further, the corotron wire is oxidized during repeated discharge action, and unevenness or the like is generated on the surface of the wire due to evaporation of metal or the like, and if the usage time is further extended, problems such as disconnection occur. If an abnormality occurs in the discharging state of the charging corotron and a high voltage flows through the shield, a problem may occur in the charging state of the photoconductor drum, and an uncharged portion may be created as a black copy. Similar to the case of the charged corotron, when the pre-transfer corotron has an abnormality, the copy becomes thin and an unclear copy is created. The image is not transferred, and problems such as white spots occur.

In order to solve the above-mentioned problem of the corotron, for example, as shown in JP-A-55-153963, a means for detecting deterioration of the corotron wire is provided. . In addition, JP-A-56-
As disclosed in Japanese Patent No. 101158, there is provided means for integrating the output current from the high voltage power supply and activating the protection circuit to stop the output of the high voltage power supply when the integrated value exceeds a certain value. Is being done. When the abnormal discharge phenomenon occurs in the corotron by using the detecting means as described above, the control circuit is operated in accordance with the abnormal state so that a good quality copy can be created. .

[0005]

Among the above-mentioned conventional examples, as shown in, for example, Japanese Patent Laid-Open No. 55-153963, it is necessary to provide a means for detecting deterioration of a corotron wire in order to provide a wire length. There is a problem that the scanning device for performing scanning while moving the image sensor in the vertical direction is expensive. Then, considering the cost of a diagnostic device and the like attached to the scanning device, it cannot be easily applied to a general electrophotographic copying machine or the like. In addition, it is not possible to detect the abnormal discharge that actually occurs in the corotron simply by detecting the change in the cross-sectional shape of the wire and dirt. There is also the problem that it is difficult to deal with such problems.

On the other hand, the above-mentioned Japanese Patent Laid-Open No. 56-1011 is used.
As shown in Japanese Patent Publication No. 58, etc., when a mechanism for performing control by integrating the output current from the high voltage power source is provided, it is possible to detect the occurrence of an abnormality according to the frequency of occurrence of a light arc or the like. . However, when the protection means as in the conventional example is provided, there arises a problem that the structure of the protection circuit of the high-voltage power supply becomes complicated in order to improve the reliability of the device. Therefore, in order to solve the above-mentioned problem of copy quality due to overdischarge of the corotron, it is a current situation that development of a cheaper and more reliable control means is desired.

[0007]

It is an object of the present invention to solve the above-mentioned problem of the conventional abnormal discharge detection mechanism of the corotron, in which a corotron output droop detection circuit is provided in the power supply circuit and the output of the corotron output droop detection circuit is provided. Input to the control device, detect the width and number of pulses of abnormal discharge, process the abnormal signal, and make a recopy when a low quality copy is made when making one copy. It is an object of the present invention to provide a corotron leak detection device that can perform processing.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an image forming apparatus in which a plurality of corotrons are arranged around a photoconductor and a toner image is formed on the photoconductor using an electrophotographic method. In the present invention, with respect to the plurality of corotrons arranged on the photoconductor, a corotron output control circuit and a corotron output droop detection circuit are respectively arranged,
A circuit for inputting the output of the corotron output droop detection circuit to the control device via a signal input circuit is configured, and a mechanism for detecting an abnormal state of the operation of the corotron is configured. Also,
In the present invention, the information on abnormal discharge of the corotron is input to the control device from the corotron output drooping detection circuit arranged for the corotron, and the discharge time of the corotron, the discharge interval, the number of discharges per sheet, etc. It is possible to configure a means for detecting an abnormal state of the corotron based on the information of abnormal discharge of. Further, in the control device of the present invention, the detection information of the abnormal state of a plurality of corotrons, and the operation of creating a copy again in the case of the preset allowable range, when the corotron exceeds the allowable range, A control means for displaying the abnormal state can be configured.

As described above, the corotron output drooping detection circuit is arranged in the corotron output control circuit arranged with respect to the corotron, and the abnormal discharge pulse is output. The state of the corotron wire can be easily detected based on information such as the distance. Therefore, by using the control means of the present invention, the state of the corotron wire can be accurately detected, and the configuration of the control device can be simplified. Further, in the present invention, when the number of occurrences of abnormal discharge during the production of one copy is within the set range, the control means for eliminating the copy with poor image quality and performing the recopy is provided. , Can eliminate low quality copies.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A corotron leak detection device according to the present invention will be described with reference to the illustrated example. As in the example shown in FIG. 1, in an apparatus that forms a toner image on a photoconductor drum by using an electrophotographic method, the charging corotron 20, the pre-transfer corotron 21, and the transfer corotron 22 are separated from each other around the photoconductor drum 3. The corotron 23 is arranged. Then, with the surface of the photosensitive drum being uniformly charged by the discharge from the charging corotron 20, the image writing unit 5
To irradiate light from the writing device to form an electrostatic latent image. To the electrostatic latent image, toner is supplied from a developing device (not shown) arranged downstream of the writing device to form a toner image, and the pre-transfer corotron 21 discharges the toner onto the photosensitive drum. With the adhesive force weakened, the toner is moved toward the transfer position of the toner image by the transfer corotron 22. At the transfer position of the toner image by the transfer corotron 22, the transfer corotron 22 is discharged from the back surface of the paper to transfer the toner image to the paper, and the paper adhering to the photosensitive drum is separated by the discharge of the peeling corotron 23. The sheet is conveyed by the conveying device 18 toward the fixing device. The paper on which the toner image is transferred is supplied from a paper feed tray (not shown) or the like, and the registration roller device 17 of the paper aligning unit aligns the leading edge of the paper with the toner image on the photosensitive drum. Is fed by.

As described above, as shown in FIG. 2, the corotron output control circuit is arranged for each of the plurality of corotrons arranged around the photosensitive drum to apply a high voltage to each corotron. Constitutes a means. In the circuit diagram shown in FIG. 2, the corotron output control circuits 25 to 25c are arranged for the four corotrons 20 to 23, respectively, to constitute means for applying a high voltage to each corotron. In addition, the corotron output control circuit for the corotron is attached to the corotron output droop detection circuits 26 to 26c, and when a leak occurs in the corotron, the fail signal detected by the corotron output droop detection circuit is output. , The signal is input to the signal input circuit 27-
A mechanism for inputting the signal from the signal input ports 28 to 28c to the control device 29 via 27c is configured. In the four corotrons, the values of the voltages applied corresponding to the respective corotrons are different, but the corotron output droop detection circuits 26 to 26c respectively have a voltage of the corotron with respect to the voltage normally applied. A means for detecting the information that the voltage droops due to the abnormal discharge is provided, and the fail signal is input to the control device 29 so that the abnormal state of the corotron can be detected.

The voltage droop information output from the corotron output droop detection circuit is output, for example, as shown in FIG. In other words, in the corotron output control circuit for the corotron, when the discharge action is normal, the voltage does not droop, but when a leak occurs, the fail signal corresponds to the time (tL) at which a leak occurs. The information to be input is input to the control device. By inputting the leak signal output from the corotron output droop detection circuit to the control device, the control device shown in FIG. 2 treats the leak time tL as a leak when it continues for a certain period of time. To do. Further, in the control device of the present invention, an individual program is set for each of the four corotrons so that the allowable range of the leak time in the corotron can be set respectively. Furthermore, if the Corotron wire is broken, long-time leaks or short-time leaks will occur repeatedly. Set the means.

The image forming apparatus of the present invention in which the control means as described above is arranged can be constructed, for example, as shown in FIG. Image forming apparatus 1 shown in FIG.
Then, the top tray 9 is arranged on the upper part of the apparatus, and the discharge tray 8 is arranged on the side portion of the apparatus main body to discharge a normal copy to the discharge tray. A means for discharging toward is provided. Further, in the control panel 2 of the apparatus, a display unit is arranged to display a defect in the corotron wire when the corotron wire is defective, and a signal indicating that the corotron wire is broken is output from the control device shown in FIG. Then, make the display. In the image forming apparatus 1, the laser light output from the writing device 4 is reflected by the mirror 4a and writing is performed by the light irradiation unit of the photoconductor drum 3 as in the case of a general digital electrophotographic copying machine. A mechanism for performing a toner image is arranged. In order to feed the paper from the photoconductor drum 3 to the image transfer portion, a plurality of paper feed trays 11 are provided in the paper feed portion 10 arranged at the lower part of the apparatus.
11b and the large-capacity trays 12 are arranged, and the sheet feeding devices 13 to 13c are arranged at the sheet feeding portions of these trays.

Each of the sheet feeding devices 13 to 13c is composed of a sheet feeding roller pressed against a sheet and a sheet separating device, and sends out the sheet, one by one, toward the sheet conveying path 15. Then, the sheet aligning device 16 arranged on the downstream side of the sheet conveying path 15 aligns the sheets, and drives the registration roller device 17 in synchronization with the position of the toner image formed on the photosensitive drum 3. Then, the paper is sent toward the transfer position by the transfer corotron 22. As described above, the sheet on which the toner image has been transferred is sent to the fixing device 6 by the carrying device 18, where heat and pressure are applied to fix the sheet, and the copy is discharged toward the discharge tray 8. Further, when the paper made as a copy is determined to be a defective copy, the copy is sent to the top tray 9 via the gate 7 provided in the discharge path, and the defective copy is not discharged to the discharge tray. It constitutes such means.

In the image forming apparatus having the control mechanism as shown in FIG. 2, the operation of the control information as shown in the flow chart of FIG. 5 is performed. In the flowchart of FIG. 5, when a voltage is applied to the corotron from the corotron output control circuit, in a state where no leak occurs in the corotron, in step a-1, a leak signal is not output from the corotron output droop detection circuit, and the A copy creation operation is performed. On the other hand, if a leak occurs from the corotron output droop detection circuit provided in the corotron output control circuit in step a-1, the fail signal is output to the control device. When the fail signal is input to the control device, the leak time tL is compared with the set time T in step a-3, and it is determined whether T <tL. If NO, the step is performed. After shifting to a-6, it is judged that the wire breakage of the corotron wire has occurred, the operation of the image forming apparatus is interrupted through the steps a-7 and a-8, and the abnormal state is displayed on the control panel. Try to do it.

If it is determined that T <tL in step a-3, the process proceeds to step a-4, and it is determined whether the number of leaks is within the set value NF as an allowable range. I do. Then, when the number of leaks exceeds NF, the process proceeds to step a-6, and the process for the disconnection of the corotron wire is performed. On the other hand, when the number of leaks is equal to or less than the set value, the process proceeds to step a-5 and the copy creation operation is normally performed. Is the allowable number tF1
If it is within the allowable range, it is ejected to the ejection tray as a normal copy. However, in the step a-5, if it is determined that the number of leaks exceeds the allowable range for one copy, it means that a normal copy has not been created. , 11 to eject the copy toward the top tray, and give an instruction to make a normal copy again.

In addition, when a recopy is made, a defective copy may be made in the step a-5. Therefore, if such a state occurs a plurality of times in succession, the corotron wire becomes defective. A-6
You can move to the step of. Then, while the operation of the image forming apparatus is interrupted, it is also possible to set a mode in which the control panel displays that a defect has occurred and causes the operator to perform a failure process. As described above, by placing the corotron output droop detection circuit in the corotron output control circuit that applies a high voltage to the corotron, the state in which a leak has occurred in the corotron is input to the control device via the signal input circuit. , In the control device, the length and number of times of the leak,
By detecting the abnormal state of the corotron using information such as the pulse width, it is possible to prevent defective copies from accumulating on the output tray and to discharge only good and high-quality copies to the output tray. .

Therefore, as described above, when the means for arranging the corotron output droop detection circuit with respect to the corotron output control circuit is used, a control program corresponding to the discharge characteristic is set for each corotron. As a result, the operation of detecting an abnormal state in each corotron can be easily performed. The image forming apparatus provided with the control means as described above may be an electrophotographic copying machine or an apparatus such as a printer using an electrophotographic system, and the writing device may also use a laser beam. The present invention is not limited to the apparatus used, but can also be applied to an electrophotographic copying machine of the type in which the reflected light of the image of the original is directly written on the photosensitive drum.

[0019]

The corotron leak detection device of the present invention comprises:
Since it is configured as described above, a corotron output droop detection circuit is provided in the corotron output control circuit arranged with respect to the corotron, and a pulse of abnormal discharge is output, in the control device, the number and time of abnormal discharge, The state of the corotron wire can be easily detected based on the information such as the discharge interval. Therefore, by using the control means of the present invention, the state of the corotron wire can be accurately detected, and the configuration of the control device can be simplified. Further, in the present invention, when the number of occurrences of abnormal discharge during the production of one copy is within the set range, the control means for eliminating the copy with poor image quality and performing the recopy is provided. ,
Low quality copies can be eliminated.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a corotron device arranged around a photosensitive drum.

FIG. 2 is a block diagram showing an arrangement of control means for a corotron.

FIG. 3 is an explanatory diagram showing a fail signal output from a corotron output droop detection circuit.

FIG. 4 is an explanatory diagram showing a configuration of an image forming apparatus to which the present invention can be applied.

FIG. 5 is a flowchart showing a control operation in the control device of the present invention.

[Explanation of symbols]

1 image forming apparatus, 2 control panel,
3 photoconductor drum, 4 writing device, 8 discharge tray, 9 top tray, 10 paper feed section,
20 charging corotron, 21 pre-transfer corotron, 22 transfer corotron, 23 peeling corotron, 25-25c corotron output control circuit, 26-
26c Corotron output droop detection circuit, 27-27c
Signal input circuit, 28-28c Signal input port, 29 Control device.

Claims (3)

[Claims] 1. An image forming apparatus in which a plurality of corotrons are arranged around a photoconductor and a toner image is formed on the photoconductor by using an electrophotographic method, wherein a corotron is provided for the plurality of corotrons arranged on the photoconductor. An output control circuit and a corotron output droop detection circuit are respectively arranged, and a circuit that inputs the output of the corotron output droop detection circuit to the control device via a signal input circuit is configured to detect an abnormal state of the operation of the corotron. A corotron leak detection device. 2. A corotron output droop detection circuit arranged for the corotron inputs information on abnormal discharge of the corotron to a control device, and the discharge time of the corotron, the discharge interval, the number of discharges per sheet, etc. The abnormal state of the corotron is detected based on the abnormal discharge information of 1.
The corotron leak detection device described in 1. 3. The control device performs detection operation information of an abnormal state of a plurality of corotrons and an operation of making a copy again in the case of a preset allowable range, and in the state of exceeding the allowable range, the corotron The corotron leak detection device according to claim 1 or 2, further comprising: a control unit that displays the abnormal state.