JP2018151493A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can find a sign that at least the ends of an image quality guarantee range in an image holding body are worn.SOLUTION: An image forming apparatus comprises: image holding bodies 21 that each have an image quality guarantee range 212 set in an image formable range 210; charging devices that each charge the image holding body 21 while in contact with at least the image formable range 210 of the image holding body 21; developing devices that each develop an electrostatic latent image formed on the image holding body 21 with developer; control means that executes a first image forming operation to develop at least even the ends 215, 216 being outside the image quality guarantee range 212 in the image formable range 210 of the image holding body 21; and output means that outputs information on a result of the first image forming operation.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image forming apparatus.

  Conventionally, as an image forming apparatus or the like having a function of estimating the cause of occurrence of an abnormal image, for example, those described in the following patent documents are known.

First, in Patent Document 1, a sample image is output as an image that is not output by normal image processing, and the sample image is read by an image input device to determine whether an abnormal image has occurred. There is shown an image forming apparatus in which a sign of occurrence of an abnormal image is found before an abnormality occurs and an action is taken at an early stage. Further, Patent Document 1 exemplifies that the abnormality is that the fixing roller and the pressure roller of the fixing device are deformed and that the photosensitive drum has a lot of moisture.
Japanese Patent Application Laid-Open No. 2004-228688 calculates an amount of deviation of image data with respect to a normal state, determines whether or not an abnormal state is based on the amount of deviation, and an abnormality that identifies an abnormal location from the state of the image forming apparatus. When it is determined that there is an abnormality by the location identification means and the state determination means, and when it is determined that there is an abnormality by the image processing means that performs image processing for abnormality according to the output of the abnormal location identification means and the state determination means 1 shows an image forming apparatus including serviceman call output means for outputting a serviceman call signal.

Patent Document 3 discloses an image input unit, an image forming unit that forms an output image on a recording medium based on the input image data, a discharge unit that discharges the recording medium on which the image is recorded, and a discharge unit. An image reading unit that outputs a read image obtained by reading the recorded recording medium, an abnormality detection image generation unit that outputs image data for abnormality detection that is likely to generate an abnormal image due to the charging unit of the image forming unit, and the abnormality Comparing means for comparing the output data from the image reading means that has read the recording medium on which the output image is formed based on the detection image data and the input abnormality detection image data, and outputting a determination result; An image forming apparatus having a determination unit capable of detecting the presence or absence of abnormality of the charging unit based on the determination result of the comparison unit is shown.
Further, in Patent Document 4, a plurality of latent image carriers are provided, a process of transferring an image from each latent image carrier to a transfer body, a failure of an optical sensor and an image forming apparatus directed to the transfer body In the image forming apparatus provided with the failure detection means for performing the prediction, when the occurrence of color streak is predicted, a transfer bias is applied to the transfer body for each latent image carrier and the transfer body is detected by the failure detection means. An image forming apparatus having a mode for detecting the surface state of the image is shown. Patent Document 4 also shows that according to this image forming apparatus, it is possible to specify an image forming unit of a color in which a sign of image failure such as a color streak has occurred.

  Furthermore, Patent Document 5 discloses an image processing apparatus having an image forming unit that forms an image, an acquisition unit that acquires a feature amount from a result of reading a chart formed by the image forming unit, and an acquisition unit that acquires the feature amount. A determination unit that determines whether or not an image formed by the image forming unit includes a defect according to the determined feature amount, and a notification unit that notifies information about a result determined by the determination unit. An image processing apparatus having a determination unit that determines whether to add an image generated from a result of reading a chart to information notified by a notification unit according to a feature amount acquired by the unit is shown.

JP 2004-133081 A JP 2007-334269 A JP 2008-170549 A JP 2008-292773 A JP 2016-46595 A

  The present invention provides an image forming apparatus capable of knowing at least a sign that an end of an image quality guarantee range in an image carrier is worn.

The image forming apparatus of the present invention (A1)
An image carrier having an image quality guarantee range set to an image formable range;
A charging device that contacts and charges at least an image formable range of the image carrier;
A developing device for developing the electrostatic latent image formed on the image carrier with a developer;
Control means for performing a first image forming operation for developing at least an end portion outside the image quality guarantee range of the image carrier of the image carrier with a developer;
Output means for outputting information on the result of the first image forming operation;
It is equipped with.

The image forming apparatus of the invention (A2) is the image forming apparatus of the invention A1,
The controller is configured to charge the image forming area of the image carrier with the charging device and develop with the developer, and with the developer without charging the image forming area of the image carrier with the charging device. Configured to perform a second image forming operation including an operation of developing;
The output means is configured to output information relating to the result of the second image forming operation.
The image forming apparatus of the invention (A3) is the image forming apparatus of the invention A2, wherein the control means executes the second image forming operation after executing the first image forming operation. It is.
The image forming apparatus of the invention (A4) is the image forming apparatus of the invention A2, wherein the control means is configured to execute the second image forming operation when there is a request for the execution. .

The image forming apparatus according to the present invention (A5) includes, in the image forming apparatus according to any one of the above inventions A1 to A4, power supply means for supplying a charging voltage to the charging device and supplying a developing voltage to the developing device.
The control unit changes at least one of the charging voltage and the development voltage supplied from the power supply unit so as to generate a potential difference that can develop an end portion outside the image quality guarantee range of the image carrier with a developer. The first image forming operation is configured to be executed.

The image forming apparatus according to the invention (A6) is the image forming apparatus according to any one of the inventions A2 to A5, and further comprises a power supply means for supplying a charging voltage to the charging device and supplying a developing voltage to the developing device.
The control means is configured to execute the second image forming operation by switching supply or non-supply of the charging voltage from the power supply means.

In the image forming apparatus according to the invention (A7), in the image forming apparatus according to any one of the inventions A1 to A6, the output means transfers the developer image formed on the image holding member onto a recording medium and outputs it. It is configured to do.
The image forming apparatus according to the present invention (A8) is the image forming apparatus according to any one of the inventions A1 to A7, wherein the output means is a developer image formed on the image carrier or an intermediate transfer member from the image carrier. The image forming apparatus includes a reading unit that reads the developer image transferred to the image forming unit, and an output unit that outputs information of an image read by the reading unit.
The image forming apparatus according to the invention (A9) is the image forming apparatus according to the invention A8, further comprising display means for displaying information of the read image output from the output unit.

  According to the image forming apparatus of the invention A1, it is possible to know a sign that at least the end of the image quality guarantee range of the image carrier is worn.

In the image forming apparatus of invention A2, the abnormality of the charging device can also be known.
In the image forming apparatus according to the invention A3, it is possible to know whether a sign of abnormality has occurred in the photoconductor alone or in addition to abnormality in the charging device.
In the image forming apparatus according to the invention A4, it is possible to avoid unnecessary execution of the second image forming operation as compared with a case where the second image forming operation is configured to be executed even when there is no request for the execution. Can do.

In the image forming apparatus according to the invention A5, it is not necessary to separately provide a device for generating a potential difference that can be developed with the developer at the end portion outside the image quality guarantee range, and the first image forming operation can be easily performed.
In the image forming apparatus according to the invention A6, the second image forming operation can be easily performed as compared with the case where the supply or non-supply of the charging voltage from the power supply unit is not switched.

In the image forming apparatus of the invention A7, the result of the first image forming operation and the result of the second image forming operation when executed can be known by visually observing the developer image on the recording medium.
In the image forming apparatus of the invention A8, the result of the first image forming operation and the result of the second image forming operation when executed can be obtained as information of the read image.
In the image forming apparatus of the invention A9, the result of the first image forming operation and the result of the second image forming operation when executed can be easily known by visually observing the contents displayed on the display means.

1 is an explanatory diagram illustrating a configuration of an image forming apparatus according to Embodiment 1 and the like. FIG. 2 is an explanatory diagram illustrating an enlarged configuration of an image forming apparatus in the image forming apparatus of FIG. 1. FIG. 2 is a block diagram illustrating a partial configuration of a control system in the image forming apparatus of FIG. 1. It is explanatory drawing which shows the structure of each site | part, etc. in a photosensitive drum. (A) is explanatory drawing which shows the electric potential relationship on the photosensitive drum at the time of forming a normal image, (b) is explanatory drawing which shows the electric potential relationship on the photosensitive drum at the time of performing 1st image forming operation | movement. It is explanatory drawing which shows the example of a result output when performing 1st image formation operation | movement. (A) is explanatory drawing which shows the electrical potential relationship on a photosensitive drum when performing 2nd image formation operation (first half operation | movement) in the image forming apparatus which concerns on Embodiment 2, (b) is 2nd image formation operation | movement ( FIG. 10 is an explanatory diagram showing a potential relationship on the photosensitive drum when executing the latter half operation). It is explanatory drawing which shows the example of a result output when performing 2nd image forming operation | movement (1st half operation | movement). It is explanatory drawing which shows the example of a result output when performing 2nd image formation operation | movement (second half operation | movement). It is explanatory drawing which shows the process in which the edge part abrasion in a photosensitive drum shows, (a) shows the relationship between a photosensitive drum and a charging roll, (b) shows the initial state of the partial wear in a photosensitive drum, (c). Indicates a state in which the partial wear of the photosensitive drum is in progress, and (d) indicates a state in which end wear has occurred on the photosensitive drum.

  Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as “embodiments”) will be described with reference to the accompanying drawings.

[Embodiment 1]
1 to 3 show an image forming apparatus 1 according to the first embodiment. 1 shows the configuration of the image forming apparatus 1, FIG. 2 shows the configuration of the image forming apparatus in the image forming apparatus 1, and FIG. 3 shows the configuration of a part of the control system in the image forming apparatus 1. .

<Overall Configuration of Image Forming Apparatus>
The image forming apparatus 1 employs an electrophotographic system, and finally forms an image composed of toner on a recording sheet 9 as an example of a recording medium based on image information including characters, photographs, figures, and the like. is there.
As shown in FIG. 1, the image forming apparatus 1 includes a casing 10 having a box-like appearance as a whole, and the casing 10 is configured with toner as a developer. An image forming device 20 that forms a toner image, an intermediate transfer device 30 that holds the toner image formed by the image forming device 20 by primary transfer and then transports it to a secondary transfer position for secondary transfer to the recording paper 9, and an intermediate transfer device 30 A paper feeding device 40 for storing and supplying the recording paper 9 supplied to the secondary transfer position of the transfer device 30, a fixing device 50 for fixing the toner image secondarily transferred by the intermediate transfer device 30 to the recording paper 9, and the like. Has been placed.
The housing 10 is formed with a support structure portion and an exterior portion using materials such as a support member and an exterior material, for example. A one-dot chain line shown in FIG. 1 is a main conveyance path of the recording paper 9 inside the housing 10.

In addition, the image forming apparatus 1 includes an operation display device 14 having an input unit 14a for inputting instructions, conditions, and the like regarding the operation of the image forming apparatus 1 and a display unit 14b for displaying various information such as the conditions and states of the operation. A central control device 60 and the like that control the overall operation of the entire image forming apparatus 1 (the above-described devices and the like) are also arranged.
Further, as will be described later, the image forming apparatus 1 has a function of knowing a sign of abnormality related to at least some of the components.

The image forming apparatus 20 includes four image forming apparatuses 20Y, 20M, 20M, 20M, 20M, 20M, 20M, 20M, 20M, and 20D respectively forming developer (toner) images of four colors of yellow (Y), magenta (M), cyan (C), and black (K). 20C and 20K are used.
As shown in FIGS. 1 and 2, each of the image forming apparatuses 20 (Y, M, C, and K) includes a photosensitive drum 21 that is an example of an image holding member that is rotationally driven in a required direction. A charging device 22, an exposure device 23, a developing device 24, a primary transfer device 25, a drum cleaning device 26, a static eliminator 27, and the like are disposed around each photosensitive drum 21.

Among these, the photosensitive drum 21 forms, for example, an image forming surface (image forming range) having a photo-dielectric layer (photosensitive layer) made of a photosensitive material on the peripheral surface of a cylindrical or columnar conductive substrate to be grounded. This is a drum-shaped photoconductor. The photosensitive drum 21 is provided so as to be driven to rotate in a direction indicated by an arrow A by receiving power from a rotation driving device (not shown).
The charging device 22 is, for example, a contact-type charging device that includes a charging roll 221 that is disposed in a state of rotating in contact with the image forming surface of the photosensitive drum 21 and is supplied with a required charging voltage.

The exposure apparatus 23 is, for example, a non-scanning exposure apparatus configured using light emitting diodes and optical components, or a scanning exposure apparatus configured using optical components such as a semiconductor laser and a polygon mirror. is there. The exposure device 23 receives image information input from the outside through a communication means, a reading device, etc., and image information stored in an internal storage unit after each image component (not shown) has undergone a required process, and each color component ( Y, M, C, and K) are input as image signals that have been decomposed. The exposure device 23 performs exposure according to the input image signal.
The developing device 24 is, for example, a developing device 24 (Y, M, C, K) that uses a two-component developer including toner of any one of the four colors (Y, M, C, K) and a magnetic carrier. It is. Further, the developing device 24 (Y, M, C, K) is used, for example, to perform reversal development by charging the toner to a negative polarity. Further, the developing device 24 (Y, M, C, K) holds a two-component developer housed in the housing and rotates a developing roll 241 etc. that rotates so as to be conveyed to a developing region facing the photosensitive drum 21. I have. For example, a developing voltage obtained by superimposing an alternating current component on a direct current component is supplied to the developing roll 241.

The primary transfer device 25 is, for example, disposed so as to contact and rotate (following an intermediate transfer belt 31 described later) on an image forming surface portion as a primary transfer position of the photosensitive drum 21 and to perform a required primary transfer. It is a contact type transfer device provided with a primary transfer roll to which voltage is supplied.
The drum cleaning device 26 is disposed so as to contact at least the image forming surface portion after the primary transfer of the photosensitive drum 21 in the cleaning work opening of the housing, and scrapes unnecessary materials such as residual toner on the image forming surface. A cleaning member such as an elastic plate to be removed is provided.
The static eliminator 27 neutralizes the surface of the image forming surface of the photosensitive drum 21 by, for example, exposure (dissipation of electric charge) to make the surface potential almost zero.

The intermediate transfer device 30 is disposed at a position below the four image forming devices 20 (Y, M, C, K).
The intermediate transfer device 30 is disposed so as to rotate in the direction indicated by the arrow B while passing through the primary transfer position facing the primary transfer device 25 of the photosensitive drum 21 in the image forming device 20 (Y, M, C, K). The intermediate transfer belt 31 is provided.
The intermediate transfer belt 31 is formed into an endless belt shape having a required thickness and electric resistance value using a material in which a resistance adjusting agent such as carbon is dispersed in a base material such as polyimide resin or polyamide resin. is there.
The intermediate transfer belt 31 is supported around a plurality of support rolls 32a to 32e so as to be rotatable. The support roll 32a is a drive roll, the support roll 32b is a driven roll that holds the primary transfer surface in cooperation with the drive roll 32a, and the support roll 32c applies tension to the intermediate transfer belt 31 and meanders the intermediate transfer belt 31. The support roll 32d is configured as a secondary transfer backup roll, and the support roll 32e is configured as a cleaning backup roll.

The intermediate transfer device 30 stays on a secondary transfer device 35 that secondarily transfers the toner image transferred onto the intermediate transfer belt 31 onto the recording paper 9 and an image holding surface on the outer peripheral surface of the intermediate transfer belt 31. A belt cleaning device 36 and the like for removing unnecessary substances such as adhering toner and cleaning are provided.
The secondary transfer device 35 includes, for example, a contact member such as a secondary transfer roll disposed so as to contact and rotate the image holding surface portion supported by the secondary transfer backup roll 32d of the intermediate transfer belt 31. A contact type transfer device is employed. In the secondary transfer device 35, a contact member such as a secondary transfer roll is grounded, and a required secondary transfer voltage is supplied to the secondary transfer backup roll 32d.
The belt cleaning device 36 is disposed in contact with at least the image holding surface portion after the secondary transfer of the intermediate transfer belt 31 in the cleaning work opening of the housing, and an unnecessary object such as residual toner on the image holding surface. It is provided with a cleaning member such as an elastic plate for scraping and cleaning.

The paper feeding device 40 is arranged at a position below the intermediate transfer device 30.
The sheet feeding device 40 is detachably attached to the housing 10 and accommodates a recording body 9 in which recording sheets 9 having a desired size and type are stacked on a stacking plate (not shown), A delivery device 42 is provided for feeding the recording paper 9 from the container 41 one by one toward the paper feed path. The number of containers 41 and delivery devices 42 is increased or decreased as necessary.
Further, the sheet feeding device 40 supplies the recording paper 9 from a sheet feeding tray (not shown) used in the state opened to the outside of the housing 10 so as to join a middle portion of a supply conveyance path (Rt1) described later. A paper feed mechanism is provided.
The recording paper 9 can be applied as long as it is a recording medium that can be transported by a transport path in the housing 10 and can transfer and fix a toner image. For example, the recording paper 9 is cut into a predetermined size. In addition to paper, special media such as postcards and special media such as envelopes can also be used.

The fixing device 50 is disposed at a position below the intermediate transfer device 30.
The fixing device 50 includes a heating unit configured to rotate in a direction indicated by an arrow and to maintain a surface temperature at a predetermined temperature inside a housing 51 in which an introduction port 51a and a discharge port 51b of the recording paper 9 are formed. The heating rotator 52 in the form of a roll or a belt heated by the heating member 52 and the heating rotator 52 in the form of a roll or belt that rotates in contact with a predetermined pressure in a state substantially along the axial direction of the heating rotator 52. A pressure rotating body 53 is installed. In the fixing device 50, a portion where the heating rotator 52 and the pressing rotator 53 come into contact with each other serves as a fixing processing unit in which the recording paper 9 holding the toner image is introduced and fixing processing (heating and pressing) is performed. It is configured.

Further, the image forming apparatus 1 includes a supply conveyance path Rt1 that connects between the sheet feeding apparatus 40 and the intermediate transfer apparatus 30 as a main sheet conveyance path inside the housing 10, and a secondary transfer position of the intermediate transfer apparatus 30. A relay conveyance path Rt2 that connects between the fixing device 50 and the sheet discharge port 11 between the fixing apparatus 50 and the housing 10 is provided.
The supply conveyance path Rt1 is a conveyance path that conveys and supplies the recording paper 9 delivered from the paper feeding device 40 to the secondary transfer position of the intermediate transfer device 30, and is not shown as a plurality of paper conveyance roll pairs 45a to 45d and the like. It is composed of a plurality of paper guide members and the like. The relay conveyance path Rt2 is a conveyance path that conveys the recording paper 9 after the secondary transfer to the fixing device 50, and includes, for example, an intake belt conveyance device 46. The paper discharge transport path Rt3 is a transport path for transporting the recording paper 9 on which an image has been formed after fixing so as to be discharged to the discharge accommodating portion 12, and includes a plurality of discharge roll pairs 47a and 47b and a paper guide member (not shown). It is configured.

<Basic Image Forming Operation by Image Forming Apparatus>
In the image forming apparatus 1, a basic image forming operation described below is performed. Here, an operation in the case of forming a full-color image configured by combining toner images of four colors (Y, M, C, K) will be described as an example.

First, in the image forming apparatus 1, when the central controller 60 receives a request command for an image forming operation from the outside or the like, in each of the four image forming apparatuses 20 (Y, M, C, and K), each photosensitive drum 21 is moved to an arrow A. Each charging device 22 is supplied with a charging voltage to generate a contact discharge. As a result, the image forming surface of each photosensitive drum 21 is charged to a required polarity (eg, negative polarity) and potential.
Subsequently, each exposure device 23 performs exposure according to the image signal that has been separated into each color component (Y, M, C, K) on the image forming surface of each photosensitive drum 21 after charging. Thereby, an electrostatic latent image of each color component having a predetermined potential is formed on the image forming surface of each photosensitive drum 21.

Subsequently, each developing device 24 (Y, M, C, K) supplies toner of a color (Y, M, C, K) charged to a predetermined polarity (minus polarity) from the developing roll, A developing electric field formed between the developing roll 241 and the photosensitive drum 21 in response to the development voltage is electrostatically attached to the electrostatic latent image portion of each color component on the image forming surface of the photosensitive drum 21. As a result, toner images of corresponding colors among the four colors (Y, M, C, K) are individually formed on the image forming surface of each photosensitive drum 21.
Subsequently, each primary transfer device 25 is supplied with a primary transfer voltage to form a primary transfer electric field between the primary transfer device 25 and the photosensitive drum 21, whereby the toner image on each photosensitive drum 21 is transferred to the intermediate transfer belt in the intermediate transfer device 30. Primary transfer is performed in order (Y, M, C, K) on the 31 image holding surfaces. The drum cleaning device 26 cleans the image forming surface of each photosensitive drum 21 after the primary transfer or the like. Further, the static eliminator 27 neutralizes the image forming surface of each photosensitive drum 21 after the primary transfer or the like to prepare for the next image forming operation on each photosensitive drum 21.

  Next, in the intermediate transfer device 30, the intermediate transfer belt 31 rotates in the direction indicated by the arrow B, whereby the unfixed toner image that is primarily transferred and held on the image holding surface faces the secondary transfer device 35. Transport to the next transfer position. On the other hand, in the paper feeding device 40, the delivery device 42 sends the required recording paper 9 from the container 41 to the supply conveyance path Rt 1, and then sends it to the secondary transfer position of the intermediate transfer device 30 via the supply conveyance path Rt 1. Supply. At the secondary transfer position, the secondary transfer device 35 receives the supply of the secondary transfer voltage and forms a secondary transfer electric field between the secondary transfer device 31 and the four colors on the intermediate transfer belt 31. The toner image is secondarily transferred to one side of the recording paper 9.

Next, the recording sheet 9 on which the unfixed toner image is secondarily transferred is separated from the intermediate transfer belt 31 and then conveyed so as to be sent to the fixing device 50 via the relay conveyance path Rt2. In the fixing device 50, the recording paper 9 is heated and pressurized when it is introduced into and passed through the fixing processing unit which is a contact portion between the heating rotator 52 and the pressing rotator 53. As a result, the toner constituting the toner image is melted under pressure, and the toner image is fixed on the recording paper 9.
Subsequently, the recording paper 9 on which the toner image has been fixed is discharged from the inside of the casing 51 of the fixing device 50 and then transported via the paper discharge transport path Rt3, and finally from the paper discharge port 11 to the casing. 10 is discharged to the outside and accommodated in the discharge accommodating portion 12.

  By performing the above operation, one recording sheet 9 on which a full-color image is formed on one side is output. When a request command for a plurality of image forming operations is received, the image forming operation is repeated in the same manner for the number of sheets.

  In addition, the image forming apparatus 1 forms a monochrome image by operating any one of the four image forming apparatuses 20 (Y, M, C, K) in the image forming operation. It is also possible to form a color image other than a full-color image by operating two or three of the image forming devices 20 (Y, M, C, K) in combination.

<Function to know signs of component abnormality>
The image forming apparatus 1 has the following configuration as a function for knowing a sign of abnormality such as at least the end of the image quality guarantee range of the photosensitive drum 21 being worn.
That is, as shown in FIGS. 3 and 5, the image forming apparatus 1 develops at least the end portions 215 and 216 outside the image quality guarantee range 212 in the image formable range 210 of the photosensitive drum 21 with the developer. Control means 61 for executing the first image forming operation, and output means 70 for outputting information on the result of the first image forming operation.

Here, the image formable range 210 of the photosensitive drum 21 is a range excluding left and right end portions (portions where image formation is impossible) in the axial direction D of the photosensitive drum 21 as illustrated in FIG. More specifically, it is a portion of the image forming surface of the photosensitive drum 21 on which the photosensitive layer is formed, and is a range where an image forming operation can be performed by charging, exposing (latent image forming) and developing processes. As shown in FIG. 4, the range in which the developer is held on the developing roll 241 and development is possible (developable range) is substantially the same as the image formable range 210 of the photosensitive drum 21 in the axial direction D.
Further, the image quality guarantee range 212 of the photosensitive drum 21 is a range set inside the image formable range 210 excluding both right and left ends in the axial direction D of the photosensitive drum 21, and is actually a normal image (no border). This is the range in which the image is formed when the image is formed. Further, the image quality guarantee range 212 is a range having a width in the axial direction D substantially corresponding to the dimension of the feed width of the recording sheet having the maximum feed width among the recording sheets 9 usable in the image forming apparatus 1. .
Furthermore, the end portions 215 and 216 outside the image quality guarantee range 212 in the image formable range 210 exist at both left and right ends of the image formable range 210 excluding the image quality guarantee range 212 as illustrated in FIG. It is a part to do.

  The control means 61 includes an arithmetic processing device, a storage element, an input / output device, an external storage device, and the like. Further, the control means 61 executes a required control operation based on a program and data stored in the storage element (ROM or the like). In particular, in the first embodiment, at least the first image formation is performed. It is configured to perform an operation. The control unit 61 is configured as a part of the central controller 60, but may be configured as an independent control unit.

  As shown in FIG. 3, the control unit 61 supplies a charging voltage to the charging roll 221 of the charging device 22 and supplies the developing voltage to the developing roll 241 of the developing device 24, and the exposure device 23. It is connected to the exposure drive unit 16 to be driven, the output means 70 for outputting the result of the first image forming operation, the display unit 14b of the operation display device 14 and the like, and performs the operation such as the first image forming operation. The control signal necessary at the time is transmitted. The control means 61 is connected to the communication unit 19 for communicating information with an external device or the like, the input unit 14a of the operation display device 14, and the like, thereby obtaining information necessary for the control operation. ing.

When the control unit 61 executes the first image forming operation, the end portions 215 and 216 outside the image quality guarantee range 212 of the photosensitive drum 21 are also supplied from the developing device 24 with respect to the development voltage supplied from the power supply unit 15. The condition is changed to generate a potential difference Δα that can be developed with the supplied developer (toner).
It can be said that the first image forming operation at this time is a developing operation that causes a phenomenon (toner adhesion) in which toner adheres to the entire image forming range 210 of the photosensitive drum 21. Further, in the first image forming operation, when there are a plurality of image forming apparatuses 20 including the photosensitive drum 21 and the charging device 22, one of the plurality of image forming apparatuses 20 (Y, M, C, K) is provided. It is done sequentially while operating each one.
Further, when executing the first image forming operation, the control unit 61 controls the operation of the exposure driving unit 16 so that the exposure by the exposure device 23 is not performed and the electrostatic latent image is not formed.

The potential difference Δα is the difference between the charging (surface) potential Vh of the photosensitive drum 21 and the developing potential Vd generated by the developing voltage when the ends 215 and 216 can also be developed as illustrated in FIG. 5B. (Absolute value) Δα (Δα = | Vh−Vd |).
Actually, this potential difference Δα is based on the charging potential Vh1 when forming a normal image (FIG. 5A) as a reference, and the development potential Vd1 when forming a normal image at the end portions 215 and 216. It is generated by changing to a special development potential Vd2 (FIG. 5B) when development of the above is possible. Further, as the special development potential Vd2 at this time, for example, as shown in FIG. 5B, a potential having a magnitude exceeding the charging potential Vh1 when forming a normal image in absolute value is adopted. The This special development potential Vd2 is obtained in advance by, for example, conducting an experiment for examining a development voltage suitable for performing the development by variously changing the development voltage (actually a DC component voltage).
FIG. 5A illustrates the relationship between each potential and the like when a normal image is formed. 5A indicates the potential of the electrostatic latent image formed by exposure of the exposure device 23 with respect to the image quality guarantee range 212 of the photosensitive drum 21 after charging.

Further, the first image forming operation by the control means 61 is executed, for example, when a service engineer (service man) selects and instructs the execution mode of the first image forming operation from the input unit 14a in the operation display device 14. It is configured as follows.
In this case, the execution mode of the first image forming operation is displayed as a selection instruction screen on the display unit 14b of the operation display device 14, for example. Further, it is preferable that the execution of the first image forming operation according to the instruction of the service engineer is periodically performed according to the usage frequency progress state based on information such as the number of image formations.

For example, the output unit 70 is configured to transfer (record) a developer image (unfixed toner image) formed on the photosensitive drum 21 by the first image forming operation onto the recording paper 9 and output it. .
The output unit 70 configured as described above is an image forming operation for forming a normal image except for changing the developing voltage and not forming an electrostatic latent image in the first image forming operation executed by the control unit 61. This is realized by setting the control contents to be performed according to the conditions in (1). In the output means 70 having such a configuration, information relating to the result of the first image forming operation is recorded on the recording paper 9 and output.

However, the recording paper 9 used at the time of output of the output means 70 needs to enable transfer of a toner image formed by development on the end portions 215 and 216 outside the image quality guarantee range of the photosensitive drum 21. The exceptional recording paper (paper for confirmation) 9B whose feed width is substantially the same as the dimension along the axial direction D of the image formable range 210 on the photosensitive drum 21 is used (FIG. 5). 6).
The special recording paper 9B is sent out from the paper feeding device 40 to the secondary transfer position of the intermediate transfer device 30 when it can be stored in the container 41 in the paper feeding device 40 and sent out by the feeding device 42. Supplied. On the other hand, if the special recording paper 9B cannot be supplied from the paper supply device 40, for example, the special recording paper 9B is stored in a manual tray in a manual paper supply mechanism (not shown) and then sent out to be joined in the middle of the supply conveyance path Rt1. It is supplied to the secondary transfer position of the transfer device 30.

<First image forming operation>
In the image forming apparatus 1, when the execution mode of the first image forming operation is selected and instructed from the input unit 14 a of the operation display device 14 by the service engineer, the following first image forming operation is executed by the control unit 61. The

  The first image forming operation at this time is performed a total of four times while operating the four image forming devices 20 (Y, M, C, K) one by one. Here, representatively, the first image forming operation when the black color K image forming device 20K is operated will be described.

  When the first image forming operation is performed, in the image forming device 20K, the image forming possible range 210 of the rotating photosensitive drum 21 is charged by the charging device 22 so as to have the same charging potential Vh1 as that during normal image formation. Then, the light is passed through without being exposed by the exposure device 23, and is developed through the development device 24K to which the development voltage for the first image forming operation is supplied.

At this time, as shown in FIG. 5B, the photosensitive drum 21 in the image forming device 20K is charged so that the image formable range 210 becomes a negative polarity charging potential Vh1, while the first image forming is performed. When the developing voltage for operation is supplied, the developing roller 241 of the developing device 24K showing a special developing potential: Vd2 having a negative polarity exceeding the charging potential Vh1 is opposed.
As a result, a potential difference Δα1 (= Vd2−Vh1) is generated between the photosensitive drum 21 and the developing roll 241 to develop the end portions 215 and 216 outside the image quality guarantee range 212 of the photosensitive drum 21. For example, when “−550V” is applied as the charging potential Vh1 and “−600” is applied as the special development potential Vd2, the potential difference Δα1 is “50V” in absolute value.
As a result, the entire photosensitive drum 21 including the end portions 215 and 216 outside the image quality guarantee range 212 and the entire image formable range 210 is developed with black toner charged with a negative polarity.

  Subsequently, the black toner image formed on the photosensitive drum 21 at the time of the first image forming operation is primarily transferred to the intermediate transfer belt 31 of the intermediate transfer device 30 and conveyed, and then a special recording sheet at the secondary transfer position. Secondary transferred to 9B. Finally, the black toner image at the time of the first image forming operation is fixed on the special recording paper 9B by the fixing device 50, and then output to the discharge container 12 in a state of being recorded on the special recording paper 9B. .

Thus, the first image forming operation by the operation of the image forming device 20K is completed.
Further, in the first image forming operation, after the operation process by the operation of the black image forming device 20K is completed, the remaining color image forming devices 20 (Y, M, C) are sequentially operated independently. It is executed in the same way.

  When this first image forming operation is executed, the service engineer examines and examines the image on the special recording sheet 9B that is finally output. Thus, the service engineer can know whether or not there is a sign that at least the end of the image quality guarantee range 212 in the photosensitive drum 21 is worn (end wear).

In other words, the output special recording paper 9B is formed with an image in which the toner adheres almost uniformly over the entire area of one side.
At this time, for example, in the vicinity of the left and right end portions in the width direction W substantially perpendicular to the transport direction E of the special recording paper 9B after output, for example, it extends in a streak pattern along the transport direction E illustrated in FIG. It may be confirmed that there are visible dark image portions K1, K2. In this case, it can be known that there is a sign that end wear of the photosensitive drum 21 occurs.
On the other hand, in the vicinity of the left and right end portions of the special recording paper 9B after output, the presence of the dark image portions K1 and K2 that look like the stripes may not be confirmed. In this case, it can be known that there is no sign that end wear of the photosensitive drum 21 occurs.

  Thus, the reason for knowing the sign of the abnormal end wear on the photosensitive drum 21 is related to the occurrence of end wear on the photosensitive drum 21 as follows.

  First, when the photosensitive drum 21 is charged by contact with the charging roll 221 of the charging device 22, the rotation shaft 223 of the charging roll 221 is disposed at both ends in the axial direction D as illustrated in FIG. If it is supported in a state where it receives the applied pressure F, it will be in the following state. In other words, the charging roll 221 in the above-described supporting state is bent as if it is shaped so as to be away from the outer peripheral surface of the photosensitive drum 21 at the center and toward the direction approaching the photosensitive drum 21 at both ends. It will be like a state. For this reason, the photosensitive drum 21 is placed in a state where the left and right ends of the charging roll 221 are kept in contact with a relatively strong pressure.

As a result, as illustrated in FIG. 10B, the photosensitive drum 21 has a portion where the left and right ends of the charging roll 221 are in strong contact (usually, an outer portion of the image forming range 210) extending in the circumferential direction. It begins to be worn like a streak (reference numeral 219 is a worn portion). Further, as the usage amount of the photosensitive drum 21 increases, the stripe-shaped wear portion 219 is formed on the inner side (center portion) along the axial direction D as illustrated in FIGS. 10C and 10D in order. It grows unevenly so as to progress gradually so as to enter, and is in a state of uneven wear.
That is, the worn portion 219 generated on the photosensitive drum 21 grows so as to enter the end portions 215 and 216 outside the image quality guarantee range 212 of the image formable range 210 as illustrated in FIG. Finally, as illustrated in FIG. 10D, the image grows from the left and right ends of the image quality guarantee range 212 to the inside.
In this case, the stage where the wear portion 219 enters the image quality guarantee range 212 (the left and right end portions thereof) is the situation where the end wear of the photosensitive drum 21 occurs. In addition, the growth speed and the extent of expansion of the friction portion 219 may be the same at the left and right ends of the photosensitive drum 21 or may be different.

The photosensitive drum 21 corresponds to the increase in the dark attenuation level when the wear portion 219 exists at least in the image formable range 210 and the thickness of the photosensitive layer decreases and the dark attenuation level increases. As a result, the rate at which the charging potential Vh of the photosensitive drum 21 decreases also increases. As a result, the wear portion 219 is made to adhere more toner in the development process, and is visualized as a portion having a higher density than normal portions other than the wear portion 219.
Therefore, the developed image including the worn portion 219 is the dark image portions K1 and K2 that appear as streaks in the vicinity of the left and right ends of the special recording paper 9B output in the first image forming operation. Recorded and appear. Further, the left and right end portions of the special recording paper 9B appearing with the image portions K1 and K2 recorded correspond to the end portions 215 and 216 outside the image quality guarantee range 212 in the photosensitive drum 21.

  From the above, if there are dark image portions K1 and K2 that look like streaks at the left and right ends of the special recording paper 9B, the wear portion 219 on the front side that develops to the original end wear is described above. Since this indicates that it has occurred on the photosensitive drum 21, the presence of the image portions K1 and K2 can be regarded as a sign of end wear.

Incidentally, if end wear occurs in the image formable range 210 of the photosensitive drum 21, when a normal image is formed, a streak-like image defect due to end wear occurs in the image.
However, when the first image forming operation is executed and the result is examined, it is possible to know a sign of end wear on the photosensitive drum 21 before the image defect occurs.

Further, when the service engineer confirms the presence of dark image portions K1 and K2 that appear to be streaks at the left and right edges of the special recording paper 9B by the first image forming operation, the service engineer checks the edges of the photosensitive drum 21. If it is determined that it is a sign of wear and the photosensitive drum 21 whose image portions K1 and K2 have been confirmed is arranged for replacement with a new photosensitive drum, or if there is a new photosensitive drum in hand Exchange work can be done on the spot.
When such a countermeasure is taken, it is possible to prevent image defects caused by end wear on the photosensitive drum 21 in advance.
In addition, by preventing the occurrence of image defects due to end wear, it is possible to identify the cause of the image defect after it has occurred and to perform necessary repair work. Further, it is possible to prevent the occurrence of an unusable time (downtime) in which the image forming apparatus 1 cannot be used while the cause of the occurrence is identified and the work of repair is performed.

[Modification of Embodiment 1]
In the first embodiment, the special developing potential Vd2 generated by the developing voltage supplied from the power supply means 15 in the first image forming operation exceeds the charging potential Vh1 during normal image formation by an amount that is equal to the potential difference Δα1. An example of the configuration for making the potential (FIG. 5B) is shown.
However, as a special development potential, as long as a potential difference that can also develop the end portions 215 and 216 outside the image quality guarantee range 212 of the photosensitive drum 21 can be obtained, a two-dot chain line in FIG. As illustrated, it is also possible to apply a developing potential: Vd3 that is a potential before the charging potential Vh1 during normal image formation. The potential difference at this time is Δα2.
When such a special development potential: Vd3 is adopted when the level of dark decay of the worn portion 219 in the photosensitive drum 21 is relatively large, the developed portion 219 is developed even with the development potential Vd3 (potential difference Δα2). It is particularly effective.

Further, in the first embodiment, the end portions 215 and 216 outside the image quality guarantee range 212 of the photosensitive drum 21 are also developed in the first image forming operation, so that the development voltage supplied from the power supply unit 15 can be developed. A corresponding configuration example is shown by changing to generate Δα1 (Δα2).
However, in the first image forming operation, for example, the potential difference Δα1 (Δα2) generates the charging voltage supplied from the power supply unit 15 while maintaining the developing voltage at the value of the developing voltage when a normal image is formed. You may change and respond | correspond.
In addition, in the first image forming operation, both the developing voltage and the charging voltage may be changed (adjusted) so as to generate the potential difference Δα1 (Δα2).

[Embodiment 2]
FIG. 7 shows the configuration and state of the second image forming operation in the image forming apparatus according to the second embodiment.
The image forming apparatus according to the second embodiment is related to the first embodiment except that a configuration capable of executing the second image forming operation by the control unit 61 is added as a function of knowing a sign of abnormality related to at least some parts. The image forming apparatus 1 has the same configuration.

<Function to know signs of component abnormality>
The image forming apparatus (1) according to the second embodiment has a configuration related to the first image forming operation as a function for knowing a sign of abnormality such as at least the end of the image quality guarantee range 212 in the photosensitive drum 21 being worn. In addition, the following configuration is provided.
That is, in this image forming apparatus, as shown in FIG. 3 and FIG. 7, the control unit 61 in Embodiment 1 charges the image forming range 210 of the photosensitive drum 21 with the charging device 22 and develops it with the developer. And a second image forming operation including an operation of developing with the developer without charging the image forming range 210 of the photosensitive drum 21 by the charging device 22. Further, in this image forming apparatus, the output unit 70 in Embodiment 1 is configured to output information related to the result of the second image forming operation as illustrated in FIG.
The former operation in the second image forming operation (operation in which the image forming range 210 of the photosensitive drum 21 is charged by the charging device 22 and developed with the developer) is an operation corresponding to the first image forming operation. Can be treated as

The control unit 61 is configured to switch whether to supply the charging voltage from the power supply unit 15 (supply or non-supply) when performing the second image forming operation (the former and the latter operations), In addition, the developing voltage supplied from the power supply unit 15 is changed so that a potential difference (Δα) that can be developed by the developer in the image formable range 210 of the photosensitive drum 21 can be generated.
Further, when executing the second image forming operation, the control unit 61 controls the operation of the exposure driving unit 16 so that the exposure by the exposure device 23 is not performed and the electrostatic latent image is not formed.

First, when executing the former operation (actually the first image forming operation) of the second image forming operation, the control unit 61 is similar to the case of the first image forming operation in the first embodiment in the same way as the power supply unit 15. 7A, the end portions 215 and 216 outside the image quality guarantee range 212 of the photosensitive drum 21 can be developed with the developer supplied from the developing device 24, as shown in FIG. The condition is changed to a condition for generating the potential difference Δα.
As illustrated in FIG. 7A, the development voltage at this time is the special development potential Vd2 generated when the changed development voltage is supplied, and the charging potential Vh1 when a normal image is formed. A voltage that has a potential exceeding the absolute value is adopted. Further, the potential difference Δα at this time is a potential difference Δα1 which is a difference (absolute value) between the charging potential Vh1 and the special development potential Vd2.

Next, when performing the latter operation of the second image forming operation, the control unit 61 stops (not supplies) the supply of the charging voltage from the power supply unit 15 as illustrated in FIG. 7B. Thus, the image formable range 210 of the photosensitive drum 21 is not charged (charging potential: Vh2 = 0), while the developing voltage is set to a voltage at which a potential difference Δα3 that can be developed in the image formable range 210 of the photosensitive drum 21 is obtained. change.
As the special development potential Vd4 at this time, a value is used in which the potential difference Δα3 is substantially the same as the potential difference Δα1 in the first image forming operation.

Further, the second image forming operation by the control means 61 is instructed by the service engineer selecting the execution mode of the second image forming operation from the input unit 14a of the operation display device 14 as in the case of the first image forming operation. When configured to run.
In this case, the execution mode of the second image forming operation is displayed as a selection instruction screen on the display unit 14b of the operation display device 14, for example. In the second embodiment, the selection instruction screen regarding the execution mode of the second image forming operation is, for example, a case where the execution mode of the first image forming operation is selected and instructed, and the first image forming operation is performed. Is configured to be displayed for the first time after ending. Further, the control means 61 is configured to control to execute the second image forming operation after executing the first image forming operation. Incidentally, the second image forming operation is not performed unless an operation for selecting and instructing the execution mode of the second image forming operation after performing the first image forming operation is performed.

The output unit 70 is, for example, a developer image (unfixed toner image) formed on the photosensitive drum 21 by the second image forming operation, as in the case of the output unit 70 for the first image forming operation in the first embodiment. Is transferred onto the recording paper 9 and output.
However, the recording paper 9 used for this output has the same feed width as the dimension in the axial direction D of the image formable range 210 of the photosensitive drum 21 as in the case of outputting the result of the first image forming operation. Thus, a special recording sheet 9B that is handled as an exception is used (FIG. 8).

<Second image forming operation>
In the image forming apparatus 1, when the service engineer selects and instructs the execution mode of the first image forming operation and the second image forming operation from the input unit 14 a of the operation display device 14, the control unit 61 performs the following first operation. An image forming operation and a second image forming operation are executed. Note that the first image forming operation at this time is the former operation in the second image forming operation as described above.

  Also, the second image forming operation is performed a total of four times while operating the four image forming devices 20 (Y, M, C, K) one by one, as in the case of the first image forming operation. Here, as a representative example, the first image forming operation when the black color K image forming device 20K is operated will be described.

  First, when the first image forming operation which is also the former operation in the second image forming operation is performed, the image forming apparatus 20K rotates as in the case of the first image forming operation according to the first embodiment described above. The image forming range 210 of the photosensitive drum 21 to be charged is charged by the charging device 22 so as to have the same charging potential Vh1 as that during normal image formation, and then passes through without being exposed by the exposure device 23, and the first image forming operation. Development is carried out through the developing device 24K to which the development voltage for use is supplied.

At this time, the photosensitive drum 21 in the image forming device 20K is charged such that the image formable range 210 becomes a negative polarity charging potential Vh1, while the developing voltage for the first image forming operation is supplied and the charging potential is supplied. This is opposed to the developing roll 241 of the developing device 24K that exhibits a special developing potential Vd2 having a negative polarity greater than Vh1.
As a result, between the charged potential Vh1 of the image formable range 210 of the photosensitive drum 21 and the special developing potential Vd2 generated on the developing roll 241, as shown in FIG. A potential difference Δα1 that develops the end portions 215 and 216 outside the image quality guarantee range 212 is also generated.
As a result, the entire area of the image formable range 210 including the end portions 215 and 216 outside the image quality guarantee range 212 is developed with the black toner charged to the negative polarity, and the photosensitive drum 21 is in a state where the toner adheres. .

  Subsequently, the black toner image formed on the photosensitive drum 21 at the time of the first image forming operation is primarily transferred to the intermediate transfer belt 31 of the intermediate transfer device 30 and conveyed, and then a special recording sheet at the secondary transfer position. Secondary transferred to 9B. Finally, the black toner image at the time of the first image forming operation is fixed on the special recording paper 9B by the fixing device 50, and then output to the discharge container 12 in a state of being recorded on the special recording paper 9B. .

Thus, the first image forming operation by the operation of the image forming device 20K is completed.
The first image forming operation is similarly performed by sequentially operating the image forming apparatuses 20 (Y, M, C) of colors other than the black color independently.

By executing the first image forming operation (the former operation in the second image forming operation), special recording paper 9B for four colors (Y, M, C) on which the result of the image forming operation is recorded is obtained. (FIG. 8).
At this time, as in the case of the description of the first image forming operation in the first embodiment, the service engineer looks at the output image on the special recording sheet 9B and examines at least the end portion of the photosensitive drum 21. It is possible to know whether or not there is a sign of wear.
That is, the density appears to extend in a streak pattern along the conveyance direction E illustrated in FIG. 8 near the left and right ends of the width direction W substantially perpendicular to the conveyance direction E of the special recording paper 9B after output. When the dark image portions K1 and K2 exist, it can be known that there is a sign that end wear of the photosensitive drum 21 occurs.

However, in the portion corresponding to the image quality guarantee range of the special recording paper 9B output by the execution of the first image forming operation, as shown in FIG. 8, the image portions K1 and K2 have a different darkness. There may be a case where the image portion K3 exists.
In this case, it is difficult to determine that there is a sign of another abnormality other than end wear in the photosensitive drum 21 based only on the presence of the image portion K3.
In particular, when the image portion K3 periodically exists at substantially the same interval along the conveyance direction E of the special recording paper 9B, the image portion K3 exists in a portion different from the image portions K1 and K2. Therefore, it cannot be determined that it is a sign that at least end wear of the photosensitive drum 21 occurs.
The second image forming operation (the latter operation) is effective when executed in such a case.

  Next, when the latter operation of the second image forming operation is performed, in the image forming device 20K, the image forming range 210 of the rotating photosensitive drum 21 is not charged by the charging device 22, and the next exposure device 23 is not charged. After passing without being exposed, development is performed through the developing device 24K to which the developing voltage for the second image forming operation is supplied.

At this time, as shown in FIG. 7B, the photosensitive drum 21 of the image forming device 20K is not charged, and the charged potential Vh2 = 0. A developing voltage for image operation is supplied to face the developing roll 241 of the developing device 24K showing a special developing potential Vd3 having a negative polarity larger than the charging potential Vh2 = 0.
As a result, the end portion 215 outside the image quality guarantee range 212 of the photosensitive drum 21 is between the charged potential Vh2 = 0 in the image formable range 210 of the photosensitive drum 21 and the special developing potential Vd4 generated on the developing roll 241. , 216 can be developed as well. For example, when “−50” is applied as the special development potential Vd4 for the charging potential Vh2 = 0, the potential difference Δα3 is “50V” in absolute value. This potential difference Δα3 is the same as the potential difference Δα1 applied during the first image forming operation.
As a result, the entire photosensitive drum 21 including the end portions 215 and 216 outside the image quality guarantee range 212 and the entire image formable range 210 is developed with black toner charged with a negative polarity.

  Subsequently, the black toner image formed on the photosensitive drum 21 at the time of the second image forming operation is primarily transferred to the intermediate transfer belt 31 of the intermediate transfer device 30 and conveyed, and then a special recording sheet at the secondary transfer position. Secondary transferred to 9B. Finally, the black toner image at the time of the second image forming operation is fixed on the special recording paper 9B by the fixing device 50, and then is output to the discharge container 12 in a state of being recorded on the special recording paper 9B. .

Thus, the latter operation in the second image forming operation by the operation of the image forming device 20K is completed.
The operations described later in the second image forming operation are similarly executed by sequentially operating the image forming apparatuses 20 (Y, M, C) of colors other than black independently.

  Even when the latter operation in the second image forming operation is executed, a special recording sheet 9B is finally output and can be obtained. At this time, the service engineer can also see whether there is another sign of abnormality in addition to the abnormal sign of end wear on the photosensitive drum 21 by examining the image on the special recording paper 9B. .

  That is, at this time, as illustrated in FIG. 9, when the dark image portion K3 that exists at the end of the first image forming operation does not exist on the special recording sheet 9B, the image portion K3 is displayed. The charging device 22 can be regarded as having disappeared due to the absence of charging, and it can be known that there is a sign of abnormality such as damage or functional deterioration that causes the image portion K3 to be formed on a part of the charging roll 221.

This is because, if there is a damaged or functionally deteriorated part causing a charging failure in a part of the charging roll 221, the part in the image forming range 210 of the photosensitive drum 21 charged by the damaged or functionally deteriorated part. The charging potential: Vh is lower than the other portions, and the potential difference from the developing potential: Vd is relatively large. As a result, the portion where the charged potential of the photosensitive drum 21 is reduced is easily developed, and a lot of toner adheres, and the image portion K3 is formed corresponding to the portion and visualized. ing.
At this time, if the period (interval) of the image portion K3 is a dimension corresponding to the outer peripheral length (circumference) of the charging roll 221, the image portion K3 may damage the above-described damage or damage to a part of the charging roll 221. There is a further possibility that the information indicates a sign of abnormality such as functional deterioration.
Therefore, when such a result is obtained, the service engineer can cope with prompt replacement of the corresponding charging device 22 (charging roll 221) with a new one and necessary repair work.

On the other hand, if the special recording paper 9B (FIG. 9) output at this time similarly has the dark image portion K3 (FIG. 8) that existed at the end of the first image forming operation, It can be inferred that damaged or degraded functions occur in the circumferential direction in the image quality guarantee range 212 of the photosensitive drum 21 at substantially the same interval.
In this case, a normal charging potential cannot be obtained at a portion where the photosensitive drum 21 is damaged or the function is deteriorated, and there is a high possibility that an image defect due to the charged potential will occur.
Therefore, when such a result is obtained, it is possible for the service engineer to cope with prompt replacement of the corresponding photosensitive drum 21 with a new one and necessary repair work.

Even when the latter operation in the second image forming operation is performed, the output special recording paper 9B has an image indicating a sign of end wear on the photosensitive drum 21, as shown in FIG. The portions K1 and K2 appear in the same manner as in the case of the output result of the first image forming operation (FIG. 8).
Further, the image portion K3 may appear in a portion of the special recording paper 9B corresponding to the end portions 215 and 216 outside the image quality guarantee range 212 of the photosensitive drum 21.

Further, as illustrated in FIG. 8, the special recording paper 9B output when the first image forming operation is performed, as illustrated in FIG. 8, has another image portion K4 that is wider in the transport direction E than the image portion K3. May appear.
In this case, if the interval between the image portions K4 is a long dimension that cannot be generated from the circumference of the charging roll 221, the image portion 4K is within the image quality guarantee range 212 of the photosensitive drum 21. It can also be assumed that this is a result obtained by damage occurring at approximately the same interval in the circumferential direction or a portion having deteriorated function.
However, even in this case, as illustrated in FIG. 9, the special recording paper 9 </ b> B output when the latter operation in the second image forming operation is executed following the first image forming operation, If it can be confirmed that the image portion K4 still appears, it can be confirmed with certainty that there is a sign of abnormality such as damage or functional deterioration in a part of the image quality guarantee range 212 of the photosensitive drum 21.

[Other embodiments]
In the first and second embodiments, as the output unit 70, for example, an output unit 70 having another configuration described below may be applied.
As the output means 70, as shown in FIG. 3 and the like, a reading means 72 for reading a toner image transferred to the intermediate transfer belt 31 when the first image forming operation or the second image forming operation is executed, and a reading An output unit 75 that outputs information of an image read by the means 72 is provided.

As the reading unit 72, for example, a line type density sensor that has a reading surface over the entire width direction of the intermediate transfer belt 31 and can individually read four color toner images is applied. As illustrated in FIG. 1, the reading unit 72 passes through all of the image forming devices 20 (Y, M, C, K) of the intermediate transfer belt 31 and reaches the secondary transfer position (image holding surface ( The outer peripheral surface) is disposed at a position facing the portion, preferably at a position facing the image holding surface portion supported by the support roll 32b or the like.
The output unit 75 outputs the read information to a device capable of confirming the information after storing the information once or immediately. As such an output unit 75, for example, a unit that displays information read and output to the display unit 14b of the operation display device 14 can be applied. In this case, for example, the position and density of the toner image secondarily transferred to the intermediate transfer belt 31 are displayed on the display unit 14b.

  When the output unit 70 configured by the reading unit 72 and the output unit 75 is adopted, the service engineer displays the result of the first image forming operation and the second image forming operation on the operation display device 14. It can be easily confirmed by looking at the content displayed on the part 14b. Also in this case, whether or not there is a sign of abnormality such as at least end wear on the photosensitive drum 21 by checking the presence or absence of the image portions K1 and K2 and the presence or absence of other image portions K3 and K4 in the display image. Can know.

Incidentally, when outputting the read information, the toner image transferred onto the intermediate transfer belt 31 may be removed by the belt cleaning device 36 without being secondarily transferred to the recording paper 9 or the like. Further, when the results of the first image forming operation and the second image forming operation are displayed and output on the display unit 14b as described above, it is not necessary to use the special recording paper 9B described above. Further, the output means 70 may be configured to have a function of recording and outputting the results of the first image forming operation and the second image forming operation on the special recording paper 9B described above.
The output unit 75 may be configured to output (including transmission) the read information to an external device other than the image forming apparatus 1.

In the first and second embodiments, when the first image forming operation or the second image forming operation is executed, the control unit 61 increases or decreases the potential difference Δα with respect to the development voltage and the charging voltage supplied from the power supply unit 15. It is also possible to adopt a configuration in which control is performed so as to change and supply the output.
When this configuration is adopted, an image portion (K1, K2, etc.) showing a sign of abnormality is identified by adjusting the density difference of the images obtained by executing the first image forming operation and the second image forming operation. It can be made easier.

In the second embodiment, when the former operation in the second image forming operation is executed, the charged photosensitive drum 21 is exposed by the exposure device 23 as illustrated by a two-dot chain line in FIG. 7A. And an electrostatic latent image may be formed within the image quality guarantee range 212.
In this case, as the electrostatic latent image, for example, a latent image for obtaining a halftone (intermediate density) image using a screen can be applied. When forming an electrostatic latent image in this way, the former operation in the second image forming operation is different from the first image forming operation (when no electrostatic latent image is formed). For example, when a latent image is formed using a screen, the appearance of an abnormal image such as a streak can be adjusted by changing the type of the screen. Further, the change allows the toner adhesion range to be controlled in the axial direction D of the photosensitive drum 21, and adjustment can be made so as not to cause unnecessary toner adhesion (dirt).

Further, regarding the image forming apparatus, any image forming apparatus provided with an image carrier such as a photoconductor, a contact-type charging device, and a developing device may be an image that employs the intermediate transfer system exemplified in the first and second embodiments. Not only the forming apparatus 1 but also other types of image forming apparatuses may be used. The intermediate transfer body in the intermediate transfer system is not limited to the belt-type intermediate transfer belt exemplified in the first embodiment, but may be a drum-type intermediate transfer drum.
When an image forming apparatus that does not employ the intermediate transfer method is applied, the reading means 72 in the output means 70 is a toner formed on an image carrier such as a photoconductor when the first image forming operation or the second image forming operation is performed. The image will be read. The image carrier is a member or structure that can hold (formation) a latent image and hold a developer image (such as a toner image) after the latent image is developed with a developer.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 9 ... Recording paper (an example of a recording medium)
9B: Special recording paper (an example of a recording medium)
14b ... Display section (an example of display means)
21 ... Photosensitive drum (an example of an image carrier)
31. Intermediate transfer belt (an example of an intermediate transfer member)
22 ... charging device 24 ... developing device 61 ... control means 70 ... output means 72 ... reading means 75 ... output unit 210 ... image formable range 212 ... image quality guarantee range 215, 216 ... end outside image quality guarantee range Δα ... potential difference

Claims (9)

An image carrier having an image quality guarantee range set to an image formable range;
A charging device that contacts and charges at least an image formable range of the image carrier;
A developing device for developing the electrostatic latent image formed on the image carrier with a developer;
Control means for performing a first image forming operation for developing at least an end portion outside the image quality guarantee range of the image carrier of the image carrier with a developer;
Output means for outputting information on the result of the first image forming operation;
An image forming apparatus. The controller is configured to charge the image forming area of the image carrier with the charging device and develop with the developer, and with the developer without charging the image forming area of the image carrier with the charging device. Configured to perform a second image forming operation including an operation of developing;
The image forming apparatus according to claim 1, wherein the output unit is configured to output information related to a result of the second image forming operation.   The image forming apparatus according to claim 2, wherein the control unit is configured to execute the second image forming operation after executing the first image forming operation.   The image forming apparatus according to claim 2, wherein the control unit is configured to execute the second image forming operation when there is a request to execute the second image forming operation. A power supply means for supplying a charging voltage to the charging device and capable of supplying a developing voltage to the developing device;
The control unit changes at least one of the charging voltage and the development voltage supplied from the power supply unit so as to generate a potential difference that can develop an end portion outside the image quality guarantee range of the image carrier with a developer. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to execute the first image forming operation. A power supply means for supplying a charging voltage to the charging device and capable of supplying a developing voltage to the developing device;
The image forming apparatus according to claim 2, wherein the control unit is configured to execute the second image forming operation by switching supply or non-supply of a charging voltage from the power supply unit.   The image forming apparatus according to claim 1, wherein the output unit is configured to transfer and output a developer image formed on the image holding member onto a recording medium.   The output unit reads a developer image formed on the image holding member or a developer image transferred from the image holding member to an intermediate transfer member, and outputs information of an image read by the reading unit. The image forming apparatus according to claim 1, comprising an output unit.   The image forming apparatus according to claim 8, further comprising a display unit that displays information of the read image output from the output unit.

Images