Patent ID: 12248267

DETAILED DESCRIPTION

Exemplary embodiments of the present disclosure will be described with reference to attached drawings.

FIG.1is a diagram illustrating an image forming apparatus100according to an exemplary embodiment.

The image forming apparatus100is an image forming apparatus of an intermediate transfer system called a tandem type.

The image forming apparatus100includes a plurality of image forming units200that form images to be transferred to paper50, which is an example of a recording medium.

Each of the image forming units200includes a photoconductor drum11, which is an example of an image holder, and forms a toner image, which is an image to be transferred to the paper50, on the photoconductor drum11, using dry developer. In other words, each of the image forming units200forms a toner image to be transferred to the paper50on the photoconductor drum11using powder developer.

Developer used in this exemplary embodiment contains powder-like dry carrier and powder-like dry toner. Each of the image forming units200forms a toner image on the photoconductor drum11using powder-like dry carrier and powder-like dry toner. In this example, carrier has a positive charging polarity and toner has a negative charging polarity.

Such dry developer is not necessarily used. Wet developer may be used.

The image forming units200use toner of different types to form toner images on the photoconductor drums11.

In this exemplary embodiment, four image forming units200: a first image forming unit200Y, a second image forming unit200M, a third image forming unit200C, and a fourth image forming unit200K.

In this exemplary embodiment, the image forming units200are disposed in the order of the first image forming unit200Y, the second image forming unit200M, the third image forming unit200C, and the fourth image forming unit200K in a moving direction of an intermediate transfer belt15.

The first image forming unit200Y forms a toner image using toner of yellow color. The second image forming unit200M forms a toner image using toner of magenta color. The third image forming unit200C forms a toner image using toner of cyan color. The fourth image forming unit200K forms a toner image using toner of black color.

The image forming apparatus100also includes the intermediate transfer belt15, which is an example of an intermediate transfer body, and a first transfer unit10for transferring toner images that have been formed by the image forming units200to the intermediate transfer belt15.

The image forming apparatus100also includes a second transfer unit20for transferring the toner images that have been transferred to the intermediate transfer belt15to the paper50.

The image forming apparatus100also includes a fixing device60that fixes the toner images that have been transferred to the paper50onto the paper50.

The image forming apparatus100also includes a controller40that includes a central processing unit (CPU) for executing a program and controls the individual components of the image forming apparatus100.

The image forming apparatus100also includes a display device45that includes a display panel or the like. The display device45receives an instruction from a user and displays information for the user. The display device45includes a touch panel. The display device45displays information for the user and receives an instruction from the user.

FIG.2is a diagram illustrating a configuration of hardware of the controller40.

The controller40includes a processing unit201and an information storage device202that stores information.

The processing unit201includes a computer.

The processing unit201includes a CPU211, which is an example of a processor that performs various processes described later. The processing unit201also includes a read only memory (ROM)212in which software is stored and a random access memory (RAM)213that is used as a work area.

The information storage device202is implemented by an existing device such as a hard disk drive, a semiconductor memory, or a magnetic tape.

The processing unit201and the information storage device202are connected by a bus206or a signal line, which is not illustrated inFIG.2.

A program to be executed by the CPU211may be stored in a computer-readable recording medium such as a magnetic recording medium (a magnetic tape, a magnetic disk, or the like), an optical recording medium (an optical disc or the like), a magneto-optical recording medium, or a semiconductor memory and provided to the controller40. The program to be executed by the CPU211may be provided to the controller40using communication means such as the Internet.

Referring back toFIG.1, the image forming apparatus100will be described more in detail.

Each of the image forming units200includes a developing device14. The developing device14makes an electrostatic latent image on the photoconductor drum11a visible image using toner.

Each of the image forming units200also includes a charging device12that charges the photoconductor drum11and an exposure device13that forms an electrostatic latent image on the photoconductor drum11.

In each of the image forming units200, the photoconductor drum11, which is an image holder, rotates in an arrow A direction.

For example, the exposure device13is a laser exposure device that emits laser. The exposure device13may be, for example, an exposure device including a plurality of light sources such as light-emitting diodes (LEDs). InFIG.1, light emitted from the exposure device13is indicated by a sign Bm.

FIG.3is a diagram for explaining the developing device14.

The developing device14includes a housing unit141that houses developer. The housing unit141includes, for example, a housing case142made of resin. The developing device14is arranged to extend along a direction from the front to rear side of the image forming apparatus100(direction orthogonal to the plane ofFIG.1).

An opening143is arranged at a position of the housing case142that faces the photoconductor drum11(seeFIG.1).

A developing roll145for causing developer to be adhered to the surface of the photoconductor drum11is provided in the opening143. The developing roll145has a column shape and is arranged to extend along in a direction from the front to rear side of the image forming apparatus100(direction orthogonal to the plane ofFIG.3).

The developing roll145has a cylindrical body and includes a developing sleeve145A that rotates in an arrow8A direction inFIG.3. The developing roll145also includes a magnetic roll145B arranged inside the developing sleeve145A. For example, the developing sleeve145A is made of metal such as steel use stainless (SUS).

Furthermore, the developing device14also includes a first transport member146and a second transport member147that transport developer.

The first transport member146is arranged to extend along the direction from the front to rear side of the image forming apparatus100and transports developer to, for example, the rear side of the image forming apparatus100.

The second transport member147is also arranged to extend along the direction from the front to rear side of the image forming apparatus100and transports developer to the front side of the image forming apparatus100.

Furthermore, in this exemplary embodiment, the space inside the housing case142is partitioned by a partition wall148. A first space148A that is located near the photoconductor drum11and a second space148B that is far away from the photoconductor drum11are arranged inside the housing case142.

In this exemplary embodiment, the first transport member146is placed in the first space148A, and the second transport member147is placed in the second space148B.

The partition wall148is not formed over the whole area in the longitudinal direction of the housing case142. The partition wall148is not provided on the rear side and the front side of the housing case142.

Both end parts in the longitudinal direction of the housing case142are parts where no partition wall148is formed.

Thus, in this exemplary embodiment, developer moves in a circulating manner inside the developing device14.

Specifically, in this exemplary embodiment, developer inside the first space148A is transported in the rear-side direction on the plane ofFIG.3by the first transport member146. Then, the developer reaches a rear-side end part of the housing case142, passes through the part where no partition wall148is formed, and moves to the second space148B.

The developer that has moved to the second space148B is transported in the front-side direction on the plane ofFIG.3by the second transport member147. Then, the developer passes through a front-side end part of the housing case142where no partition wall148is formed, and moves to the first space148A.

Such a movement of the developer is repeatedly performed, and the developer moves in a circulating manner inside the developing device14. Furthermore, in this exemplary embodiment, the developer is stirred by the circulating movement.

The developing device14further includes a layer restriction unit151above the developing roll145. The layer restriction unit151restricts part of the movement of developer adhered to the surface of the developing roll145so that the developer adhered to the surface of the developing roll145has a predetermined thickness.

The magnetic roll145B includes seven magnetic poles: N1to N4(N poles) and S1to S3(S poles) that are aligned along the circumferential direction of the magnetic roll145B.

The magnetic pole N3(pick-up pole) attracts developer transported by the first transport member146. Thus, in this exemplary embodiment, the developer is adhered to the surface of the developing sleeve145A.

The magnetic pole S2(trimming pole) makes, in cooperation with the layer restriction unit151, the developer adhered to the surface of the developing roll145have a predetermined thickness.

The magnetic poles S3, N2, and N1function as transport poles and cause the developer on the developing sleeve145A to be moved to the downstream side in the rotation direction of the developing sleeve145A.

The magnetic pole S1(developing pole), together with the magnetic pole N1that is adjacent to the magnetic pole S1, makes the developer in a brush-like form. In this exemplary embodiment, toner contained in the developer in the brush-like form moves to the surface of the photoconductor drum11(seeFIG.1), and the toner is adhered to the photoconductor drum11, which is an example of an image holder.

Thus, development is implemented, and a toner image is formed on the photoconductor drum11.

The toner image is temporarily held on the photoconductor drum11and is moved to the first transfer unit10(seeFIG.1) by the rotating photoconductor drum11.

The magnetic pole N4(pick-off pole), together with the magnetic pole N3that is adjacent to the magnetic pole N4, forms a repulsive magnetic field and peels off the developer adhered to the surface of the developing sleeve145A from the developing sleeve145A.

Referring back toFIG.1, the image forming apparatus100will be described further in more detail.

Each of the image forming units200includes a first transfer roll16that transfers, at the first transfer unit10, a toner image that has been formed on the photoconductor drum11to the intermediate transfer belt15.

Each of the image forming units200also includes a drum cleaner17that removes developer remaining on the photoconductor drum11.

The intermediate transfer belt15is moved in a circular manner at a predetermined speed in an arrow B direction indicated inFIG.1by a drive roll31that is driven by a motor, which is not illustrated inFIG.1.

The first transfer unit10includes the first transfer roll16that is arranged opposite the photoconductor drum11with the intermediate transfer belt15interposed therebetween. Toner images on the photoconductor drums11are electrostatically attracted to the intermediate transfer belt15in a sequential manner, and the toner images that are superimposed on one another are formed on the intermediate transfer belt15.

The second transfer unit20includes a second transfer roll22that is arranged on the outer surface side of the intermediate transfer belt15and a backup roll25that is arranged on the inner surface side of the intermediate transfer belt15.

In this exemplary embodiment, at the second transfer unit20, toner images that have been formed by the image forming units200and transferred to the intermediate transfer belt15are transferred to the paper50that has been transported to the second transfer unit20.

A process performed by the image forming apparatus100will be described below.

The image forming apparatus100receives image data output from, for example, an image reading device or a personal computer (PC), which is not illustrated in drawings. Then, the image forming apparatus100performs image processing on the image data. Thus, image data corresponding to the plurality of image forming units200are generated.

Specifically, for example, image data for four colors: yellow, magenta, cyan, and black, are generated. The generated image data are output to the corresponding exposure devices13provided in the corresponding image forming units200.

Each of the exposure devices13causes light emitted from, for example, a semiconductor laser, to be applied to the corresponding photoconductor drum11in accordance with the input image data.

In this exemplary embodiment, after the surface of each of the photoconductor drums11is charged by the charging device12, scan exposure to the surface is performed by the exposure device13. Thus, an electrostatic latent image is formed on the surface of the photoconductor drum11.

Next, developing processing by the developing device14is performed, and a toner image is then formed on the photoconductor drum11. At the first transfer unit10, the toner image is transferred to the intermediate transfer belt15.

After the toner image is transferred to the intermediate transfer belt15, the toner image is moved to the second transfer unit20by the movement of the intermediate transfer belt15. At this time, the paper50from a first paper housing unit53(seeFIG.1) or a second paper housing unit54is transported to the second transfer unit20by a transport roll52and the like.

Then, at the second transfer unit20, the toner images on the intermediate transfer belt15are electrostatically transferred to the paper50in a collective manner.

After that, the paper50to which the toner images haven been transferred is peeled off from the intermediate transfer belt15and transported to a transport belt55(seeFIG.1). The transport belt55transports the paper50to the fixing device60.

The paper50that has been transported to the fixing device60is heated and pressurized by the fixing device60. Thus, the toner images on the paper50are fixed to the paper50. Then, the paper50is discharged from the image forming apparatus100.

In this exemplary embodiment, a diagnosis of whether or not there is a failure is performed for each of the plurality of image forming units200. More specifically, in this exemplary embodiment, an identification as to whether or not there is a failure and an identification of a part in which the failure has occurred are able to be performed for each of the plurality of image forming units200.

In this exemplary embodiment, to make a diagnosis for an image forming unit200, for example, a specifier such as an operator first performs an operation for the display device45or the like to specify the image forming unit200as a target for the diagnosis.

In this exemplary embodiment, an image forming unit200specified by the specifier is defined as a diagnosis target image forming unit200, which is a target for a diagnosis.

A diagnosis target image forming unit200as a target for a diagnosis is not necessarily specified by the specifier. The CPU211of the image forming apparatus100may specify a diagnosis target image forming unit200based on a predetermined condition.

Furthermore, the CPU211may specify the plurality of image forming units200in order so that a diagnosis will be made for each of all the image forming units200.

A diagnosis target image forming unit200that has been specified as a target for a diagnosis forms a predetermined diagnostic image on the photoconductor drum11as an image holder. Then, the diagnostic image that has been formed on the photoconductor drum11is temporarily transferred to the intermediate transfer belt15and then transferred to the paper50.

Furthermore, in this exemplary embodiment, in addition to the diagnostic image, various types of information such as information about the diagnosis are added to the paper50to which the diagnostic image is transferred.

In this exemplary embodiment, as described below, for example, a case where identification information is added as information to the paper50to which the diagnostic image is transferred will be described.

However, information added to the paper50is not necessarily identification information. Information such as date and time information indicating the date and time when the diagnosis was made, information about the formed diagnostic image, or information about the specifier may be added to the paper50.

Moreover, both the identification information and the information other than the identification information may be added as information to the paper50.

The identification information represents information used for discriminating information associated with the identification information from different information.

In this exemplary embodiment, to add identification information to the paper50, an identification image, which is an image representing identification information, is formed on the paper50. In other words, in this exemplary embodiment, an information display image, which is an image representing information, is formed on the paper50. The identification image is an example of an information display image.

In this exemplary embodiment, the identification image is encoded identification information. Specifically, in this exemplary embodiment, the identification image is a so-called two-dimensional barcode. The identification image may be an image of a different form such as a one-dimensional barcode or may be identification information represented in a text format. In other words, the identification image may be identification information represented by text.

To add information other than the identification information to the paper50, encoded information may be added to the paper50or the information may be represented in a text format.

In this exemplary embodiment, as described above, identification information is added to the paper50to which a diagnostic image is transferred. More specifically, in this exemplary embodiment, as described above, an identification image, which is an image representing identification information, is formed on the paper50to which a diagnostic image is transferred. In other words, in this exemplary embodiment, an information display image, which is an image representing information, is formed on the paper50to which a diagnostic image is transferred.

In this exemplary embodiment, as described later, the identification image is formed by an image forming unit200different from the image forming unit200that forms the diagnostic image.

The identification image formed by the different image forming unit200is temporarily transferred to the intermediate transfer belt15and then transferred to the paper50from the intermediate transfer belt15.

In this exemplary embodiment, to form a diagnostic image on the paper50, the CPU211, which is an example of a processor, causes the different image forming unit200to operate, and causes an identification image to be formed on the photoconductor drum11provided in the different image forming unit200.

In other words, in this exemplary embodiment, in the case where a diagnostic image that has been formed by an image forming unit200specified by a specifier is transferred to the paper50and formed on the paper50, the CPU211operates the different image forming unit200, so that an identification image is formed on the photoconductor drum11provided in the different image forming unit200.

Then, in this exemplary embodiment, the identification image that has been formed on the photoconductor drum11is transferred to the intermediate transfer belt15and then transferred from the intermediate transfer belt15to the paper50on which the diagnostic image is transferred.

Thus, in this exemplary embodiment, the diagnostic image and the identification image are formed on the same paper50.

Then, in this exemplary embodiment, a diagnosis for the diagnosis target image forming unit200is made based on the paper50on which the diagnostic image and the identification image are formed.

Specifically, for example, the above-mentioned specifier visually checks the paper50on which the diagnostic image and the identification image are formed and makes a diagnosis for the diagnosis target image forming unit200.

More specifically, the specifier makes a diagnosis of whether or not there is a failure in the diagnosis target image forming unit200.

Furthermore, when it is determined that there is a failure in the diagnosis target image forming unit200, the specifier makes a diagnosis for identifying a component element in which the failure has occurred from among a plurality of component elements configuring the diagnosis target image forming unit200.

More specifically, in this exemplary embodiment, the diagnosis target image forming unit200includes component elements such as the photoconductor drum11, the charging device12, the exposure device13, the developing device14, and the first transfer roll16. The specifier makes a diagnosis for identifying a component element in which the failure has occurred from among the component elements configuring the diagnosis target image forming unit200.

Furthermore, for example, the paper50on which the diagnostic image and the identification image are formed is read by a scanner device. Thus, read image data is generated. Then, the read image data is transmitted to, for example, a management server (not illustrated in drawings).

The management server or a diagnosing person who accesses the management server makes a diagnosis for the diagnosis target image forming unit200.

Specifically, as described above, the management server or the diagnosing person makes a diagnosis of whether or not there is a failure in the diagnosis target image forming unit200.

Furthermore, when it is determined that there is a failure in the diagnosis target image forming unit200, the management server or the diagnosing person makes a diagnosis for identifying a component element in which the failure has occurred from among component elements configuring the diagnosis target image forming unit200.

In this exemplary embodiment, as described above, in the case where the diagnosis target image forming unit200forms a diagnostic image, the CPU211causes a different image forming unit200to operate, and causes an identification image formed by the different image forming unit200to be transferred to the paper50on which the diagnostic image is formed.

Thus, the paper50on which the diagnostic image that has been formed by the diagnosis target image forming unit200and the identification image that has been formed by the different image forming unit200are formed, is generated.

In other words, in this exemplary embodiment, the paper50on which the image that has been formed by the image forming unit200specified by the specifier and the identification image that has been formed by the image forming unit200that is different from the image forming unit200specified by the specifier are formed, is generated.

In other words, in this exemplary embodiment, the paper50on which the image that has been formed by the image forming unit200specified by the specifier is added and the image that has been formed by the image forming unit200that is different from the image forming unit200specified by the specifier and contains information such as identification information is added, is generated.

In the case where an identification image is formed on the paper50, the paper50on which a diagnostic image is formed is able to be identified. More specifically, for example, by forming different identification images on individual sheets of paper50, the paper50on which a diagnostic image is formed is able to be identified.

For example, by forming different identification images for individual image forming units200, an image forming unit200that has formed a diagnostic image is able to be identified.

For example, by forming different identification images for individual image forming apparatuses100, an image forming apparatus100that has formed a diagnostic image is able to be identified.

For example, by forming different identification images for individual diagnostic images formed on the paper50, a diagnostic image that has been formed on the paper50is able to be identified.

As described above, an identification image may be an identification image for identifying the paper50, an identification image for identifying the image forming unit200, an identification image for identifying the image forming apparatus100, an identification image for identifying a diagnostic image, or the like.

One of the types of identification image mentioned above may be formed on the paper50or two or more types of identification image may be formed on the paper50.

Furthermore, in addition to such an identification image or in place of such an identification image, an image containing information other than identification information may be added to the paper50.

In this exemplary embodiment, also in the case where information other than identification information is added to the paper50, an image forming unit200that is different from the diagnosis target image forming unit200forms an image containing such information and corresponding such information.

FIGS.4A and4Bare diagrams illustrating an example of the paper50on which a diagnostic image and an identification image are formed.FIG.4Aillustrates the paper50viewed from a side, andFIG.4Billustrates the paper50viewed from a direction indicated by an arrow IVB inFIG.4A. In other words,FIG.4Billustrates the paper50viewed from the front.

In the example illustrated inFIGS.4A and4B, a diagnostic image91in black color is formed over substantially the entire paper50. Furthermore, in this example, as illustrated inFIG.4A, an identification image93in magenta color is formed on the diagnostic image91.

In this exemplary embodiment, in the case where the diagnosis target image forming unit200forms the diagnostic image91, the CPU211controls the plurality of image forming units200such that the identification image93is transferred on the diagnostic image91, as illustrated inFIGS.4A and4B.

In the case where the diagnosis target image forming unit200forms the diagnostic image91, the CPU211performs control such that the identification image93is formed to be superimposed on the diagnostic image91that has been transferred to the paper50, as illustrated inFIG.4A.

In this exemplary embodiment, the identification image93is arranged opposite the paper50with the diagnostic image91interposed therebetween, as illustrated inFIG.4A.

In this exemplary embodiment, as illustrated inFIG.1, in the direction in which the intermediate transfer belt15moves, the second image forming unit200M that forms the identification image93in magenta color is located upstream the fourth image forming unit200K that forms the diagnostic image91in black color.

To form the diagnostic image91and the identification image93, the identification image93in magenta color that has been formed by the second image forming unit200M is first transferred to and placed on the intermediate transfer belt15.

Then, in this exemplary embodiment, when the identification image93in magenta color on the intermediate transfer belt15reaches the fourth image forming unit200K, the diagnostic image91in black color that has been formed by the fourth image forming unit200K is transferred to the intermediate transfer belt15.

Thus, the identification image93in magenta color and the diagnostic image91in black color are formed to be superimposed on each other on the intermediate transfer belt15.

After that, in this exemplary embodiment, the identification image93in magenta color and the diagnostic image91in black color that are superimposed on each other are transferred to the paper50at the second transfer unit20. Thus, the paper50illustrated inFIGS.4A and4Bis generated.

In the case where the identification image93is formed on the paper50, the CPU211causes the identification image93that has been formed by an image forming unit200that forms an image in a color different from the color of the diagnostic image91to be transferred to the paper50.

Specifically, in this exemplary embodiment, for example, in the case where the color of the diagnostic image91is black, the CPU211causes the identification image93in magenta color, which has been formed by the second image forming unit200M that forms an image in magenta color, to be transferred to the paper50.

In other words, for example, in the case where a target for a diagnosis is the fourth image forming unit200K and the color of the diagnostic image91is black, the CPU211causes the second image forming unit200M that forms an image in magenta color to operate to form the identification image93in magenta color.

Alternatively, for example, in the case where the color of the diagnostic image91is black, the CPU211causes an identification image93in cyan color, which has been formed by the third image forming unit200C that forms an image in cyan color, to be transferred to the paper50.

In other words, for example, in the case where a target for a diagnosis is the fourth image forming unit200K and the color of the diagnostic image91is black, the CPU211causes the third image forming unit200C that forms an image in cyan color to operate to form the identification image93in cyan color.

In the case where the color of the identification image93is black and the identification image93is formed using only one color, it is desirable that the color of the identification image93be magenta.

An inventor has found by experiment that the recognition rate of the identification image93read by machine is higher in magenta than cyan or yellow.

In the case where the color of the diagnostic image91is not black, for example, the CPU211causes an identification image93in black color, which has been formed by the image forming unit200that forms an image in black color, to be transferred to the paper50.

In other words, for example, in the case where the color of the diagnostic image91is not black but a color such as cyan, magenta, or yellow, the CPU211causes the fourth image forming unit200K that forms an image in black color to operate to form the identification image93in black color.

In this case, as illustrated inFIGS.5A and5B, which illustrate another example of the paper50on which a diagnostic image and an identification image are formed, the identification image93in black color is placed on the paper50and the diagnostic image91in a color not black is placed on the identification image93in black color.

FIG.6includes diagrams illustrating states of the image forming unit200.

In part (A) ofFIG.6, the state of an image forming unit200at a normal time is illustrated. In other words, part (A) ofFIG.6illustrates the state of the image forming unit200at the time when the image forming unit200performs normal image formation.

In this exemplary embodiment, at the normal time, the photoconductor drum11is charged by the charging device12so that the potential of the surface of the photoconductor drum11becomes VH.

Furthermore, at the normal time, the photoconductor drum11is irradiated with light by the exposure device13in a selective manner. The potential of a part of the photoconductor drum11where an image is to be formed is set to a potential VL, which is lower than the potential of the developing roll145.

Thus, toner from the developing roll145is adhered to the part of the photoconductor drum11that has the potential VL, and a toner image is formed on the part that has the potential VL. Then, the toner image is transferred to the paper50via the intermediate transfer belt15, and the toner image is thus formed on the paper50.

At the normal time, to reduce the density of an image to be formed, as indicated by sign6A in part (A) ofFIG.6, in addition to the time during which the photoconductor drum11is irradiated with light, the time during which the photoconductor drum11is not irradiated with light is provided, and a part where no image is formed is thus formed.

A dot-shaped toner image is formed in a part of the photoconductor drum11that is irradiated with light, whereas toner is not adhered to a part of the photoconductor drum11that is not irradiated with light and a blank region is thus formed in the part that is not irradiated with light.

In this exemplary embodiment, the density of an image to be formed varies according to the size of a dot-shaped toner image and the size of a blank region. When the blank region is relatively large, it appears to the user that the density of the image decreases.

In this exemplary embodiment, at the time of normal image formation, density control is performed on a screen so that the density of an image to be formed decreases.

Parts (B) to (E) ofFIG.6illustrate states of a diagnosis target image forming unit200for which diagnosis processing is performed.

In this exemplary embodiment, there are a plurality of diagnostic modes. The diagnosis target image forming unit200operates based on a diagnostic mode specified by the specifier. In this exemplary embodiment, there are four diagnostic modes.

In this exemplary embodiment, in the case where the diagnosis target image forming unit200forms the diagnostic image91in one of the four diagnostic modes, the identification image93that has been formed by a different image forming unit200is transferred to the paper50.

In other words, in this exemplary embodiment, in the case where the diagnostic image91is formed under a specific condition that the image forming unit200is in one of the four diagnostic modes, the identification image93that has been formed by the different image forming unit200is transferred to the paper50.

In the first diagnostic mode illustrated in part (B) ofFIG.6, as described above, the photoconductor drum11is charged so that the potential of the surface of the photoconductor drum11becomes VH.

Furthermore, in the first diagnostic mode illustrated in part (B) ofFIG.6, the photoconductor drum11continues to be irradiated with light by the exposure device13. In other words, in this processing example, the photoconductor drum11continues to be irradiated with light so that the blank region described above is not formed.

Furthermore, in the first diagnostic mode illustrated in part (B) ofFIG.6, the diagnostic image91with low image density is formed.

Specifically, in the first diagnostic mode, compared to the normal time illustrated in part (A) ofFIG.6, output of the exposure device13is reduced so that a difference Vs between the potential of the surface of the photoconductor drum11and the potential of the developing roll145decreases.

Thus, in the first diagnostic mode, the diagnostic image91with low image density is formed.

In the first diagnostic mode, the diagnostic image91with low density is formed by reducing the amount of exposure instead of providing the blank region.

In the first diagnostic mode, exposure is performed uniformly with less output of exposure, and toner from the developing roll145is adhered to the whole area on which exposure has been performed uniformly. Thus, the diagnostic image91is formed over the whole are on which exposure has been performed uniformly.

In the first diagnostic mode, if light emitted from the exposure device13is uneven, gradation caused by the unevenness of light appears more clearly in the diagnostic image91formed.

In this case, existence of a failure in the diagnosis target image forming unit200is able to be identified. In other words, in this case, existence of a failure in a component element of the diagnosis target image forming unit200is able to be identified.

In the case where the density of an image is reduced by forming a dot-shaped image and a blank region as in the normal time described above, even if unevenness occurs in a plurality of dot-shaped images formed, the influence of the unevenness is less likely to appear in the diagnostic image91.

In contrast, in the first diagnostic mode illustrated in part (B) ofFIG.6, for example, remarkable density unevenness appears in the diagnostic image91, and it is clear that there is a failure in the image forming unit200.

In this exemplary embodiment, in the case where a diagnosis is made in the first diagnostic mode, a different image forming unit200is caused to operate to form the identification image93.

Thus, in the first diagnostic mode, not only the diagnostic image91that has been formed by the diagnosis target image forming unit200but the identification image93that has been formed by the different image forming unit200is also placed on the paper50.

In the first diagnostic mode, the exposure device13is caused to operate, unlike in the third diagnostic mode or the fourth diagnostic mode, which will be described later. Thus, the diagnosis target image forming unit200is able to form the identification image93.

However, in the case where the diagnosis target image forming unit200forms the identification image93as well as the diagnostic image91, the potential or the like of each of the component elements of the diagnosis target image forming unit200needs to be changed in the process of image formation. In this case, a secondary failure, which is a failure caused by complication of the process or a change in the middle of the process, may occur.

Furthermore, in the first diagnostic mode, in the case where the identification image93is formed from the middle, the area of the diagnostic image91may decrease. In this case, it is difficult to detect periodic unevenness in which the density of an image changes periodically.

In the case where the area of the diagnostic image91is small, the possibility that the diagnostic image91has a periodic unevenness for one period is lower than the case where the area of the diagnostic image91is not small.

It is desirable that periodic unevenness for at least one period be included in the diagnostic image91for which detection of periodic unevenness is performed. As described above, in the case where the area of the diagnostic image91is small, it is difficult to detect periodic unevenness.

Thus, in this exemplary embodiment, in the case where processing is performed in the first diagnostic mode, a different image forming unit200is caused to operate to form the identification image93.

In this case, the identification image93is able to be formed without changing a processing condition for the diagnosis target image forming unit200in the middle of the process. Furthermore, in this case, a reduction in the area of the diagnostic image91formed is suppressed, and detection of periodic unevenness or the like is performed easily.

Part (C) ofFIG.6is a diagram illustrating the state of the diagnosis target image forming unit200in the case where a process is performed in the second diagnostic mode.

In the second diagnostic mode, the charging potential VH of the photoconductor drum11and the potential of the developing roll145are set to be smaller than those in the first diagnostic mode described above. Furthermore, in the second diagnostic mode, the photoconductor drum11continues to be irradiated with light by the exposure device13and output of the exposure device13is set to be higher than that in the first diagnostic mode described above.

In the second diagnostic mode, the charging potential VH of the photoconductor drum11is low and the output of the exposure device13is high. Thus, when exposure is performed, the potential of the photoconductor drum11decreases to the residual potential of the photoconductor drum11.

Furthermore, in the second diagnostic mode, as described above, the surface of the photoconductor drum11is exposed with light in a uniform manner. Developer is adhered to the part exposed with light in the uniform manner, and a toner image not including the blank region described above is formed as the diagnostic image91, as described above.

In the second diagnostic mode, even if there is a small failure in the charging device12or the exposure device13, the failure does not affect the potential of the photoconductor drum11. In this case, even if there is a failure in the charging device12or the exposure device13, the influence of the failure is less likely to appear in the diagnostic image91.

In this processing example, regardless of whether or not there is a failure in the charging device12or the exposure device13, the potential of the photoconductor drum11decreases to the residual potential, and the potential of the photoconductor drum11is substantially constant regardless of whether or not there is a failure in the charging device12or the exposure device13.

A case where an image defect such as density unevenness or a streak appears in the diagnostic image91formed in the first diagnostic mode in which the potential of the photoconductor drum11does not decrease to the residual potential will be assumed.

In contrast, a case where such an image defect does not appear in the diagnostic image91formed in the second diagnostic mode in which the potential of the photoconductor drum11decreases to the residual potential will be assumed.

In this case, it is able to detect that there is no failure in the first transfer unit10or the developing device14.

In this exemplary embodiment, also in the case where the process is performed in the second diagnostic mode, a different image forming unit200is caused to operate to form the identification image93.

Also in the second diagnostic mode, the exposure device13is caused to operate. Thus, the diagnosis target image forming unit200is able to form the identification image93. However, because of the reason mentioned above, the different image forming unit200is caused to form the identification image93in the process in the second diagnostic mode.

Thus, also in the second diagnostic mode, the identification image93that has been formed by the different image forming unit200as well as the diagnostic image91that has been formed by the diagnosis target image forming unit200is placed on the paper50.

Part (D) ofFIG.6illustrates the state of the diagnosis target image forming unit200in the third diagnostic mode.

In the third diagnostic mode, as indicated by sign6C, the potential of the developing roll145is set to be higher than the charging potential VH of the photoconductor drum11. Furthermore, in the third diagnostic mode, exposure processing for the photoconductor drum11is not performed.

Also in this case, toner adhered to the developing roll145moves to the photoconductor drum11, and a toner image is uniformly formed on the surface of the photoconductor drum11.

In the third diagnostic mode, the diagnostic image91is formed on the photoconductor drum11over the whole area in the axis direction of the photoconductor drum11, and the band-shaped diagnostic image91extending in both the axis direction of the photoconductor drum11and the circumferential direction of the photoconductor drum11is formed on the photoconductor drum11.

In the third diagnostic mode, exposure processing is not performed. Thus, no control is performed regarding the position to which toner is to be adhered, and toner is adhered to the photoconductor drum11over the whole range in the axis direction of the photoconductor drum11whose whole area in the axis direction has been charged.

The “whole area in the axis direction of the photoconductor drum11” represents the entire area of a region of the photoconductor drum11in which a toner image is supposed to be formed and does not represent the entire area between one end part and the other end part in the axis direction of the photoconductor drum11.

In the third diagnostic mode, detection of whether or not there is a failure in the exposure device13is able to be performed.

In the case where, for example, a streak-shaped image defect has occurred in the diagnostic image91in the first diagnostic mode in which exposure processing is performed and such a streak-shaped image defect has not occurred in the diagnostic image91in the third diagnostic mode in which exposure processing is not performed, it is detected that there is a failure in the exposure device13.

In this exemplary embodiment, also in the third diagnostic mode, the CPU211causes the different image forming unit200to operate, and causes the identification image93formed by the different image forming unit200to be transferred to the paper50on which the diagnostic image91is formed.

In this processing example, as described above, a band-shaped toner image extending in the axis direction of the photoconductor drum11and the circumferential direction of the photoconductor drum11is formed without exposure processing being performed, and formation of the identification image93is not able to be performed.

Thus, in this exemplary embodiment, also in the third diagnostic mode, the different image forming unit200is caused to operate, and causes the identification image93formed by the different image forming unit200to be transferred to the paper50.

In this exemplary embodiment, as described above, in the case where the diagnostic image91is formed without exposure processing being performed for the photoconductor drum11, the CPU211causes the different image forming unit200to operate to form the identification image93.

Thus, also in this case, the identification image93is able to be formed on the paper50on which the diagnostic image91that has been formed by the diagnosis target image forming unit200is formed.

More specifically, in the third diagnostic mode, the paper50illustrated inFIGS.4A and4Bor the paper50illustrated inFIG.5A or5Bis generated.

Also in the third diagnostic mode, exposure processing is able to be performed. However, as described above, if a processing condition is changed in the middle of the process, the process may become complicated or a secondary failure may occur.

Specifically, a failure in which carrier in the developing device14moves to the photoconductor drum11may occur as a secondary failure. More specifically, in the third diagnostic mode, as indicated by sign6D, if exposure processing is performed, the potential difference Vd between the photoconductor drum11and the developing roll145increases, and, for example, a failure in which carrier in the developing device14moves to the photoconductor drum11may occur.

In contrast, in the case where the different image forming unit200forms the identification image93, occurrence of such a failure is reduced.

Part (E) ofFIG.6illustrates the state of the diagnosis target image forming unit200in the fourth diagnostic mode.

In the fourth diagnostic mode, the potential of the photoconductor drum11is set to zero. Furthermore, the potential of the developing roll145is set to be higher than the potential of the photoconductor drum11.

Thus, also in this case, toner adhered to the developing roll145moves to the photoconductor drum11, and as described above, the band-shaped diagnostic image91extending in both the axis direction of the photoconductor drum11and the circumferential direction of the photoconductor drum11is formed on the surface of the photoconductor drum11.

Also in this processing example, as described above, exposure is not performed. Thus, the diagnosis target image forming unit200is not able to form the identification image93.

Furthermore, in the fourth diagnostic mode, even if exposure is performed, the potential of a part of the photoconductor drum11on which exposure has been performed is still zero, and the identification image93is not able to be formed even if exposure is performed.

In this exemplary embodiment, also in the fourth diagnostic mode, the CPU211causes the different image forming unit200to operate, and causes the identification image93formed by the different image forming unit200to be transferred to the paper50on which the diagnostic image91is formed.

Thus, also in the fourth diagnostic mode, the identification image93is formed on the paper50on which the diagnostic image91is formed.

More specifically, in the fourth diagnostic mode, the paper50illustrated inFIG.4A or4Bor the paper50illustrated inFIG.5A or5Bis generated.

In the fourth diagnostic mode, a failure that may occur in the charging device12or the exposure device13is able to be detected.

In the case where an image defect has occurred in the first diagnostic mode in which charging processing and exposure processing are performed and such an image defect has not occurred in the fourth diagnostic mode in which neither the charging processing nor the exposure processing is performed, it may be detected that there is a failure in the charging device12or the exposure device13.

Each of the second to fourth diagnostic modes described above may be considered as a mode for identifying a component element in which a failure has occurred from among a plurality of component elements configuring the diagnosis target image forming unit200.

Furthermore, the diagnostic image91formed in each of the second to fourth diagnostic modes may be considered as a diagnostic image91for identifying a component element in which a failure has occurred from among the plurality of component elements configuring the diagnosis target image forming unit200.

In this exemplary embodiment, in the case where the diagnosis target image forming unit200operates in one of the second to fourth diagnostic modes, the diagnostic image91that has been formed by the diagnosis target image forming unit200and the identification image93that has been formed by the different image forming unit200are placed on the same paper50.

Furthermore, the first diagnostic mode may be considered as a mode for identifying whether or not there is a failure in the diagnosis target image forming unit200. Furthermore, the diagnostic image91formed in the first diagnostic mode may be considered as a diagnostic image91for identifying whether or not there is a failure in the diagnosis target image forming unit200.

In this exemplary embodiment, also in the case where the diagnosis target image forming unit200operates in the first diagnostic mode, the diagnostic image91that has been formed by the diagnosis target image forming unit200and the identification image93that has been formed by the different image forming unit200are placed on the same paper50.

(Others)

The configuration in which the intermediate transfer belt15is provided is described above. However, the intermediate transfer belt15is not necessarily provided, and an image formed by each of the image forming units200may be directly transferred to the paper50passing through the image forming units200in order.

As described above, with the configuration in which images are directly transferred to the paper50, by disposing an image forming unit200of a color, such as magenta, not black, downstream the image forming unit200of black, the identification image93in magenta color or the like is able to be formed on the diagnostic image91in black color, as described above.

Furthermore, with the configuration in which images are directly transferred to the paper50, by disposing the image forming unit200of black downstream an image forming unit200of magenta or the like, the identification image93in black is able to be formed on the diagnostic image91in color not black.

Furthermore, the case where a single diagnosis target image forming unit200is caused to operate and a diagnostic image91corresponding to the diagnosis target image forming unit200is formed has been described above. In other words, for example, the case where there is a single diagnosis target image forming unit200has been described.

However, the number of diagnosis target image forming units200is not limited to one. Two or more diagnosis target image forming units200may be provided.

In this case, for example, images formed by two diagnosis target image forming units200are superimposed on each over on the intermediate transfer belt15, and the superimposed images formed by the two diagnosis target image forming units200are defined as a diagnostic image91.

More specifically, in this case, the two diagnosis target image forming units200are caused to operate in one of the first to fourth diagnostic modes, and images that have been formed by the two diagnosis target image forming units200and superimposed on each other on the intermediate transfer belt15are used as a diagnostic image91.

More specifically, for example, the first image forming unit200Y (seeFIG.1) and the second image forming unit200M are caused to operate, and a yellow toner image and a magenta toner image that have been formed by the corresponding diagnosis target image forming units200and superimposed on each other are used as a diagnostic image91.

Also in this case, as described above, for example, the fourth image forming unit200K, which is different from the two diagnosis target image forming units200, is caused to operate to form an identification image93in black color.

In the embodiments above, the term “processor” refers to hardware in a broad sense. Examples of the processor include general processors (e.g., CPU: Central Processing Unit) and dedicated processors (e.g., GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, and programmable logic device).

In the embodiments above, the term “processor” is broad enough to encompass one processor or plural processors in collaboration which are located physically apart from each other but may work cooperatively. The order of operations of the processor is not limited to one described in the embodiments above, and may be changed.

The foregoing description of the exemplary embodiments of the present disclosure has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the disclosure and its practical applications, thereby enabling others skilled in the art to understand the disclosure for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the following claims and their equivalents.

APPENDIX

(((1)))

An image forming apparatus comprising:a plurality of image forming units that form images to be transferred to a recording medium; anda processor configured to cause an information display image to be transferred to a recording medium to which a diagnostic image that has been formed by a diagnosis target image forming unit, which is an image forming unit as a target for a diagnosis among the plurality of image forming units, is transferred, the information display image being an image representing information and having been formed by a different image forming unit.
(((2)))

The image forming apparatus according to (((1))), wherein the processor is configured to cause the information display image that has been formed by an image forming unit that forms an image in a color different from a color of the diagnostic image to be transferred to the recording medium.

(((3)))

The image forming apparatus according to (((2))), wherein the processor is configured to, in a case where the color of the diagnostic image is black, cause the information display image in magenta color that has been formed by an image forming unit that forms an image in magenta color to be transferred to the recording medium.

(((4)))

The image forming apparatus according to (((2))), wherein the processor is configured to, in a case where the color of the diagnostic image is not black, cause the information display image in black color that has been formed by an image forming unit that forms an image in black color to be transferred to the recording medium.

(((5)))

The image forming apparatus according to any one of (((1))) to (((4))), wherein the processor is configured to cause the information display image to be transferred in such a manner that the diagnostic image that has been transferred to the recording medium and the information display image are superimposed on each other.

(((6)))

The image forming apparatus according to any one of (((1))) to (((5))), wherein the processor is configured to, in a case where the diagnosis target image forming unit forms the diagnostic image under a specific condition, cause the information display image that has been formed by the different image forming unit to be transferred to the recording medium.

(((7)))

The image forming apparatus according to (((6))), wherein the processor is configured to, in a case where the diagnosis target image forming unit forms the diagnostic image under a condition that the diagnosis target image forming unit forms the diagnostic image without performing exposure processing for an image holder, cause the information display image that has been formed by the different image forming unit to be transferred to the recording medium.

(((8)))

The image forming apparatus according to (((6))), wherein the processor is configured to, in a case where the diagnosis target image forming unit forms the diagnostic image under a condition that the diagnosis target image forming unit forms the diagnostic image without performing charging processing and exposure processing for an image holder, cause the information display image that has been formed by the different image forming unit to be transferred to the recording medium.

(((9)))

The image forming apparatus according to (((1))), wherein the processor is configured to, in a case where the diagnostic image for identifying a component element in which a failure has occurred from among a plurality of component elements configuring the diagnosis target image forming unit is formed by the diagnosis target image forming unit, cause the information display image that has been formed by the different image forming unit to be transferred to the recording medium.

(((10)))

The image forming apparatus according to (((1))), wherein the processor is configured to, in a case where the diagnostic image is formed on an image holder provided in the diagnosis target image forming unit over a whole area in an axis direction of the image holder, cause the information display image that has been formed by the different image forming unit to be transferred to the recording medium.

(((11)))

An image forming apparatus comprising:a plurality of image forming units that form images to be transferred to a recording medium; anda processor configured to cause an information display image to be transferred to a recording medium to which an image that has been formed by a specified image forming unit, which is an image forming unit specified by a specifier from among the plurality of image forming units, is transferred, the information display image being an image representing information and having been formed by a different image forming unit.
(((12)))

A program for causing a computer to execute a process comprising:causing an information display image to be transferred to a recording medium to which a diagnostic image that has been formed by a diagnosis target image forming unit, which is an image forming unit as a target for a diagnosis among a plurality of image forming units, is transferred, the information display image being an image representing information and having been formed by a different image forming unit.
(((13)))

A program for causing a computer to execute a process comprising:causing an information display image to be transferred to a recording medium to which an image that has been formed by a specified image forming unit, which is an image forming unit specified by a specifier from among a plurality of image forming units, is transferred, the information display image being an image representing information and having been formed by a different image forming unit.
(((14)))

A recording medium on which:a diagnostic image that has been formed by an image forming unit as a target for a diagnosis among a plurality of image forming units; andan information display image that is an image representing information and has been formed by a different image forming unit among the plurality of image forming unitsare formed.
(((15)))

The recording medium according to (((14))), wherein the diagnostic image and the information display image are superimposed on each other.

(((16)))

The recording medium according to (((15))),wherein the diagnostic image is in black color, andwherein the information display image is in magenta color.
(((17)))

The recording medium according to (((15))),wherein the diagnostic image is not in black color, andwherein the information display image in black color.
(((18)))

A recording medium on which:an image that has been formed by an image forming unit that has been specified by a specifier from among a plurality of image forming units; andan information display image that is an image representing information and has been formed by a different image forming unit among the plurality of image forming unitsare formed.