JP2002244497A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems that the investigation of the cause of an image failure is not easy and a long time is required for the recovery of the image failure or an unnecessary exchange of a charge eliminating means is carried out when the image failure has occurred due to an abnormality in the charge eliminating means such as an exposure mean before electrification. SOLUTION: In the device, a potential detection means detecting an abnormality in the charge eliminating means is provided and an alarm signal is outputted when the output of the potential detection means exceeds a reference value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image on a recording material by an electrophotographic method, and more particularly to a technique for detecting an abnormality of a charge erasing means for erasing a charge on a photosensitive member.

[0002]

2. Description of the Related Art As is well known, an electrophotographic system forms a toner image on a photoconductor by charging, exposing, and developing the photoconductor, and transfers the formed toner image to a recording material. This is an image forming method in which an image is formed on a recording material by fixing.

[0003] In the electrophotographic image forming step, the charging,
Cleaning is performed after exposure, development, and transfer, and a number of images are formed by repeating these processes. In many electrophotographic image forming apparatuses, charge erasing means for erasing charges on a photoconductor is used. That is, a charge erasing unit that performs a charge erasing process after cleaning is provided. The charge erasing means usually comprises an LED (light emitting diode) array arranged in the width direction of the photoreceptor, such as in the direction of the rotation axis of the photoreceptor, and uniformly irradiates the moving photoreceptor onto the photoreceptor. Erase the remaining charge. By this charge erasing process, the charges remaining unevenly due to the electrostatic latent image formed in the previous image forming step are erased, and the surface potential of the photoconductor is made uniform. As a result, a clear image without fog or density unevenness is formed.

In an electrophotographic image forming apparatus,
A charge erasing unit that performs a charge erasing process after the development process and before the transfer process is provided. By this charge erasing process, the electrostatic force adsorbing the toner on the photoreceptor is erased, the transfer rate of the toner image is increased, and uniform transfer is performed.

Further, in an electrophotographic image forming apparatus,
After the transfer process, a charge erasing unit that performs a charge erasing process before the cleaning process is provided. By this charge erasing process, the electrostatic force adsorbing the toner is erased, and the cleaning is favorably performed.

The charge erasing means is properly used depending on various conditions in the electrophotographic image forming process or the characteristics of the photoreceptor, and any one or more of the charge erasing means is used.

When an abnormality occurs in the charge erasing means, phenomena such as non-uniform charge distribution on the photosensitive member occur, and image defects such as fog and density unevenness occur. Therefore, conventionally, when an image defect occurs, the cause of the defect is investigated, and when it is determined that the image defect is caused by an abnormality of the charge erasing unit, the problem is solved by replacing the charge erasing unit. .

Further, the charge erasing means has been replaced at the time of periodic inspection.

[0009]

Image defects such as fog and density unevenness can occur in each of charging, exposure, development, transfer and cleaning processes. Requires special measuring equipment and time. For this reason, when an abnormality occurs in the charge erasing means, the only means is to stop using the image forming apparatus, make a service call, and wait for recovery by service staff.

Further, the life of the charge erasing means is not uniform depending on the use conditions of the image forming apparatus. Conventionally, the charge erasing means has been uniformly replaced at the time of periodic inspection of the image forming apparatus regardless of whether the charge erasing means is good or not, thereby increasing the running cost of the image forming apparatus.

An object of the present invention is to solve the above-mentioned problem associated with the abnormality of the charge erasing means.

[0012]

[Means for Solving the Problems] An image forming apparatus comprising: a photoreceptor; a charge erasing unit for erasing charges on the photoreceptor; and a potential detecting unit for detecting a surface potential of the photoreceptor subjected to the charge erasing process by the charge erasing unit.

2. 2. The image forming apparatus according to claim 1, further comprising a warning unit that generates a warning signal when a potential detected by the potential detecting unit exceeds a reference value.

3. When the detection potential of the potential detection means exceeds the reference value, the correction means corrects an input to the charge erasing means, and when the correction potential exceeds the correction range, the warning means generates a warning signal. 3. The image forming apparatus according to item 2, wherein

4. 3. The image forming apparatus according to claim 2, further comprising a display unit that performs a warning display in response to a warning signal from the warning unit.

5. The image forming apparatus according to the above item 2 or 4, further comprising a transmission unit that transmits a warning signal from the warning unit to the outside.

6. A charging unit for charging the photosensitive member; and a control unit for performing charging by the charging unit, charge erasing processing by the charge erasing unit, and potential detection by the potential detecting unit together with warming-up when the apparatus is powered on. The image forming apparatus according to any one of the above items 1 to 5.

[7] A charging unit for charging the photosensitive member, and a control unit for performing charging by the charging unit, charge erasing processing by the charge erasing unit, and potential detection by the potential detecting unit for each of a predetermined number of image forming steps. The image forming apparatus according to claim 1.

8. 8. The image forming apparatus according to claim 7, wherein the control unit performs the charging by the charging unit, the charge erasing process by the charge erasing unit, and the potential detection by the potential detecting unit together with the warm-up at the time of turning on the power.

9. 9. The image forming apparatus according to claim 1, wherein the charge erasing unit includes a pre-charging exposure unit.

10. 10. The image forming apparatus according to claim 1, wherein the charge erasing unit includes a pre-transfer exposure unit.

11. 11. The image forming apparatus according to claim 1, wherein the charge erasing unit includes a pre-cleaning exposure unit.

12. 12. The image forming apparatus according to claim 1, wherein the charge erasing unit includes an LED array.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to an embodiment of the present invention will be described with reference to FIG.

Reference numeral 1 denotes a photoreceptor. An organic photoreceptor having a photosensitive layer in which an organic photoconductor is dispersed in a resin is preferable from the viewpoint of environmental friendliness and cost. be able to. The photoconductor 1 is not limited to the illustrated drum-shaped photoconductor, but may be a belt-shaped photoconductor. A charging unit 2 charges the photoconductor 1 and forms a uniform potential on the photoconductor 1. As the charging means,
A scorotron charger having a control grid and a discharge electrode,
A well-known arbitrary charger such as a corotron charger and a contact-charging type charger using a roller to which a voltage is applied is used.

Reference numeral 3 denotes exposure means for exposing the photoreceptor 1.
The exposure means is preferably a scanning exposure apparatus having a laser diode as a light source and having a scanning optical system composed of a polygon mirror, a lens and a mirror, or a scanning optical apparatus having a light emitting diode array and an image forming optical fiber. Exposes the photoreceptor 1 according to the image data by dot exposure. However, an exposure unit that illuminates the original and projects an image of the original onto the photoreceptor may be used.

Reference numeral 4 denotes a developing means, which contains a one-component developer or a two-component developer, and conveys the developer to a developing area by a developing sleeve 41 as a developer conveying means, and forms an electrostatic latent image on the photoreceptor 1. The image is developed to form a toner image on the photoconductor 1. A DC developing bias having the same polarity as the charging polarity of the charging means 2 or a developing bias in which a DC voltage having the same polarity as the charging polarity of the charging means 2 is superimposed on the developing sleeve 41 is applied to the developing sleeve 41. Reversal development in which toner is adhered to the portion is performed. The developing means 4 is not limited to reversal development. Of course, developing means for performing regular development using toner charged to the opposite polarity to the polarity of the electrostatic latent image can also be used.

Reference numeral 5 denotes a transfer unit including a corona charger. The transfer unit 5 charges the recording material P with a polarity opposite to that of the toner on the photoconductor 1, and transfers the toner image to the recording material P.

Reference numeral 6 denotes a separating unit including a corona charger, which performs AC corona charging on the recording material P to remove the charge from the recording material P and separate it from the photoreceptor 1.

Reference numeral 7 denotes a fixing unit that fixes a toner image on the recording material P by a heating roller 71 having a built-in heat source such as a halogen lamp and a pressure roller 72 pressed against the heating roller 71.

Reference numeral 8 denotes a cleaning unit. Untransferred toner and untransferred toner adhere to the photoreceptor 1 after the transfer, and it is necessary to clean the photoreceptor 1 in order to perform the next image formation. The cleaning means 8 includes a cleaning blade 8 made of an elastic blade such as urethane rubber.
One.

LD1 is a charge erasing means and an LED (light emitting diode) array as a pre-charging exposure means, which is arrayed in the direction of the rotation axis of the photosensitive member 1, that is, in the width direction of the photosensitive member 1. It consists of a group of LED elements. LED
The array LD1 uniformly exposes the rotating photoconductor to expose the photoconductor 1
Erase the upper charge. LD2 is a charge erasing unit, and an LED (light emitting diode) as a pre-transfer exposure unit
An array is composed of a group of LED elements arranged in an array in the rotation axis direction of the photoconductor 1, that is, in the width direction of the photoconductor 1. The LED array LD2 uniformly exposes the rotating photoconductor 1 to erase charges on the photoconductor 1.

ES denotes potential detecting means for scanning the entire surface of the rotating photosensitive member 1 to detect the surface potential of the photosensitive member 1.
The non-uniformity of the rotation direction of the potential on the photosensitive member 1 is determined by the potential detecting means E
Detected by S.

The image forming process is started by rotating the photosensitive member 1. A toner image is formed on the photoconductor 1 by charging of the charging unit 2, image exposure of the exposure unit 3, and development of the developing unit 4. The photoconductor after development is an LED array LD
The charge erasing process is performed by the uniform exposure of 2. As a result of the charge erasing process, the charges on the photoconductor 1 are erased,
The attraction force attracting the toner image to the photoreceptor 1 weakens,
In the next transfer step, the toner is easily transferred from the photosensitive member 1 to the recording material P, so that the transfer rate is increased and uniform transfer is performed. The photoconductor 1 passes through the transfer unit 5 after the charge erasing process, and the toner image is transferred to the recording material P. The recording material P to which the toner image has been transferred is separated from the photoconductor 1 by the separating unit 6 and is conveyed to the fixing unit 7. In the fixing unit 7, the toner image is heated and fixed to the recording material P, and the recording material P on which the image is formed is discharged. On the other hand, the photoreceptor 1 that has passed through the transfer unit 5 is cleaned by the cleaning unit 8 and then uniformly exposed by the LED array LD1. By the uniform exposure of the LED array LD1, the residual charge of the electrostatic latent image formed on the photoconductor 1 in the image forming process is erased, and the potential on the photoconductor 1 is made uniform.

FIG. 2 is a diagram showing an electrical configuration of the image forming apparatus according to the embodiment of the present invention. In FIG. 2, D
M is a photoconductor drive motor that rotationally drives the photoconductor 1, DP is a display unit that displays a warning based on a warning signal, and SU is a transmission unit that transmits a warning signal to the outside. CR is a control unit composed of a microcomputer, and controls the entire image forming apparatus. Control means CR for comparing means CMP for comparing the output of the potential detecting means ES with a predetermined reference value;
Correction means CP for correcting LED arrays LD1 and LD2
S and a warning means OUT that outputs a warning signal, and has programs as the comparison means CMP, the correction means CPS, and the warning means OUT.

The image forming apparatus has a charge erasing means inspection mode. In the charge erasing unit inspection mode, the control unit CR controls the motor DM and the charging unit 2 to uniformly charge the photoconductor 1. Next, the LED array LD1 is driven to perform a charge erasing process on the charged photoconductor 1, and the potential on the photoconductor 1 subjected to the charge erasing process is detected by the potential detecting means ES. The control means CR compares the detected output with a reference value predetermined by the comparison means CMP, and outputs a warning signal from the warning means OUT when the output exceeds the reference value. The warning signal is displayed on the display means DP or transmitted to the outside by the transmission means SU.

In the inspection mode of the LED array LD2, the control means CR performs the same control as described above.

Even when the outputs of the LED arrays LD1 and LD2 change, it may be possible to correct the light emission output by controlling the drive voltage. The control means CR has a correction means CPS, and performs feedback control based on the output of the potential detection means ES. With this correction function, the control means CR does not output a warning signal within the correctable range, and performs uniform charge erasure by correction.

The correction and warning control using the correction means CPS are performed as follows. When the output of the potential detecting means ES exceeds the reference value, the LE is detected by using the correcting means CPS.
The output of these LED arrays is corrected by controlling the drive voltage of the D array LD1 or LD2. After the correction, the charging by the charging unit 2, the exposure by the LED array LD1, and the potential detection by the potential detecting unit ES are performed again. If the surface potential of the photoconductor 1 exceeds the reference value even after the correction, , The control means CR issues a warning signal. LE
Similar correction and potential detection are performed for the D array LD2, and if unevenness is detected in the surface potential of the photoconductor 1 even after the correction, the control unit CR issues a warning signal.

In the charge erasing means inspection mode, the power supply of the image forming apparatus is turned on, that is, the main switch MS.
Is executed when is turned on. The control means CR is activated by turning on the main switch MS, turns on the fixing device 7 to start warm-up, and executes the charge erasing means inspection mode.

The charge erasing means inspection mode is executed after a predetermined number of images have been formed, except when the power of the apparatus is turned on. That is, the control means CR has a counting means CT for counting the number of formed images, and executes the charge erasing means inspection mode at the end of the image forming step in which the count value of the counting means CT reaches a predetermined number.

In the above description, the charge erasing means, the LED array LD1 and the charge erasing means as the pre-charging exposure means, and the LED array LD2 as the pre-transfer exposure means have been described. Depending on the configuration of the charging unit 2, the exposing unit 3, the developing unit 4, the transferring unit 5, and the cleaning unit 8, which are the units for executing the forming process, or the characteristics of the photoconductor 1, the LED array L
A configuration using only one of D1 and LD2 is possible. Further, a uniform exposure means as a charge erasing means may be provided before the cleaning processing by the cleaning means 8. Also in this configuration, at least one of the pre-charging exposure unit, the pre-transfer exposure unit, and the pre-cleaning exposure unit is used, and the residual potential after charge erasure by these charge erasure units is detected to detect abnormality. Is done.

[0043]

According to any one of the first, second, and ninth to twelfth aspects of the present invention, the abnormality of the charge erasing means can be detected without waiting for the analysis of the image defect. It becomes possible to take. Further, it is easy to find the cause of the image defect.

According to the third aspect of the present invention, even when an abnormality occurs in the charge erasing means, the correction is automatically performed.
An image defect caused by an abnormality of the charge erasing means is prevented, and a good image can be always formed.

According to the fourth aspect of the present invention, it is possible to quickly grasp that an abnormality has occurred in the charge erasing means.

According to the fifth aspect of the present invention, it is possible for a service institution such as a service station to quickly grasp that an abnormality has occurred in the charge erasing means in the image forming apparatus.

According to the sixth, seventh or eighth aspect of the present invention, the abnormality detection of the charge erasing means is automatically executed, so that an image defect due to the abnormality of the charge erasing means is prevented.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a mechanical configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an electrical configuration of the image forming apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoreceptor 2 charging means 3 exposure means 4 developing means 5 transfer means 6 separation means 7 fixing means 8 cleaning means P recording material CR control means ES potential detection means LD1, LD2 LED array OUT warning means SU transmission means

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) G03G 21/08 G03G 21/00 342 21/14 372 (72) Inventor Hiroyuki Watanabe 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Shares In-house (72) Inventor Akira Okamoto 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica shares In-house F-term (reference) 2H027 DA02 DE05 EA10 EA20 EC06 EC10 EC11 ED26 EE07 EE10 EF02 EF09 EJ15 GB07 HA04 HA10 HB15 2H035 AA09 AB01 AB01 AB06 AC02 AC06 AZ05

Claims (12)

[Claims] 1. A photosensitive member, comprising: charge erasing means for erasing electric charge on the photosensitive member; and potential detecting means for detecting a surface potential of the photosensitive member erased by the charge erasing means. Image forming apparatus. 2. The image forming apparatus according to claim 1, further comprising a warning unit that generates a warning signal when a potential detected by the potential detecting unit exceeds a reference value. 3. A correction means for correcting an input to the charge erasing means when a potential detected by the potential detecting means exceeds the reference value, and when the potential exceeds the correction range, the warning means issues a warning signal. The image forming apparatus according to claim 2, wherein the image is generated. 4. The image forming apparatus according to claim 2, further comprising a display unit that displays a warning in response to a warning signal from the warning unit. 5. The image forming apparatus according to claim 2, further comprising a transmission unit that transmits a warning signal from the warning unit to the outside. 6. A charging unit for charging the photosensitive member, and a control unit for performing charging by the charging unit, a charge erasing process by the charge erasing unit, and a potential detection by the potential detecting unit, together with a warm-up when the apparatus is powered on. The image forming apparatus according to claim 1, wherein: 7. A charging unit for charging the photosensitive member, and a control unit for performing charging by the charging unit, charge erasing processing by the charge erasing unit, and potential detection by the potential detecting unit every predetermined number of image forming steps. The image forming apparatus according to claim 1, wherein: 8. The control unit according to claim 7, wherein the control unit performs the charging by the charging unit, the charge erasing process by the charge erasing unit, and the potential detection by the potential detecting unit together with the warm-up at the time of turning on the power. Image forming apparatus. 9. The image forming apparatus according to claim 1, wherein the charge erasing unit includes a pre-charging exposure unit. 10. The image forming apparatus according to claim 1, wherein the charge erasing unit includes a pre-transfer exposure unit. 11. The image forming apparatus according to claim 1, wherein the charge erasing unit includes a pre-cleaning exposure unit. 12. The image forming apparatus according to claim 1, wherein said charge erasing means comprises an LED array.