JP7006075B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

Conventionally, as a technique having a function of identifying and detecting the cause of an abnormal image, for example, those described in the following patent documents are known.

In Patent Document 1, an image forming means for forming an image on a recording material, a cause grasping means for grasping the cause of a streaky image generated on an image formed on the recording material by the image forming means, and a cause grasping means are used. An image forming apparatus including an output means for outputting information about the grasped cause is shown. Further, in Patent Document 1, as a means for grasping the cause, at least one of the colors, widths and edge states of the streaky image formed on the recording material by the image forming means is grasped (causing member). Specific) is exemplified.

In Patent Document 2, as a fog manifestation device in an image forming apparatus having an image carrier, a developing means, and a transfer means, a development bias power supply that supplies a development bias to the developing means and a transfer bias are supplied to the transfer means. The transfer bias power supply, the development bias power supply, and the transfer bias power supply are controlled, and the development bias is turned on / off while changing in stages, and the transfer bias is applied at the time of image formation when the development bias is on and off. A fogging manifestation device is shown which has a control means for alternately switching between a normal transfer bias to be applied and a reverse transfer bias having the opposite polarity to the normal transfer bias, and makes fogging manifest on a recording medium. ing.

In Patent Document 3, the electrostatic latent image on the image carrier is developed by the developer supported on the developer carrier, the developer image on the image carrier is transferred to the intermediate transfer body, and then the image is transferred. An image forming apparatus that transfers a developer image on an intermediate transfer body to a sheet, and a detection means for detecting the magnitude of the electrical resistance value of the intermediate transfer body and a development bias voltage containing an AC component are applied to the developer carrier. A power supply unit that can output and change the frequency of the AC component, and if the detection value by the detection means is the first magnitude, the frequency of the AC component is set to the first value, and the detection value by the detection means is set. When the second magnitude is larger than the first magnitude, the setting means for setting the frequency of the AC component to a second value lower than the first value, and the AC component of the output development bias voltage. An image forming apparatus including a control means for controlling the power supply unit so that the frequency becomes the same as the set frequency is shown.

JP-A-2015-82053A Japanese Unexamined Patent Publication No. 2005-62858 Japanese Unexamined Patent Publication No. 2012-154965

According to the present invention, when an abnormal image of white streaks is generated, the cause of the white streaks is developed with a developing means supplied with a development bias voltage on which AC is superimposed to form a first white streak reproduction image. An image forming apparatus that can be easily estimated as compared with the case where it is not estimated from the result of the second white streak reproduction image formed by developing by the developing means to which the development bias voltage on which the AC is not superimposed is supplied. Is to provide.

The image forming apparatus of the present invention (A1) is
Image retention means,
The charging means for charging the image holding means and the charging means
A latent image forming means for forming an electrostatic latent image on the image holding means,
A developing means that is supplied with a development bias voltage capable of superimposing alternating current between the image holding means and develops the electrostatic latent image on the image holding means with a developer.
The electrostatic latent image formed in the image holding means is developed by the developing means to which the development bias voltage on which the AC is superimposed is supplied to form the first white streak reproduction image, and is formed in the image holding means. A forming means for developing a second white streak reproduction image by developing the electrostatic latent image to be developed by the developing means to which the developing bias voltage to which the AC is not superimposed is supplied.
An output means for outputting information regarding the result of the forming means, and an output means.
Equipped with
The output means outputs a first white streak reproduction image and a second white streak reproduction image formed by the formation means .

The image forming apparatus of the present invention (A2) is the image forming apparatus of the invention A1, wherein the output means is each white in the first white streak reproduction image and the second white streak reproduction image formed by the forming means. It outputs the measurement result of the concentration of the muscle part .
The image forming apparatus of the present invention (A3) is the image forming apparatus of the above invention A2 , and the output means is that the density of the white streaks in the second white streak reproduction image in the measurement result is the first white streak reproduction. When the relationship is darker than the density of the white streaks in the image, it is presumed that the cause of the white streaks is the image holding means, and in the measurement result, the density of the white streaks in the second white streak reproduction image is the second. When the relationship is thinner than the density of the white streak portion in the white streak reproduction image of 1, it is presumed that the cause of the white streak generation is the developing means, and the white streak portion in the second white streak reproduction image is estimated in the measurement result. When the density of the white streaks and the density of the white streaks in the first white streak reproduction image have the same relationship, it is estimated that the cause of the white streaks is other than the image holding means and the developing means, and the estimated result is output. It is a thing.

The image forming apparatus of the present invention (A 4 ) is the image forming apparatus of the invention A1, wherein the output means is each of the first white streak reproduction image and the second white streak reproduction image formed by the forming means. The density of the image portion and each white streak portion is measured to calculate the density difference between the image portion and the white streak portion, respectively, and the density difference in the second white streak reproduction image is the first white streak. It calculates the white streak contrast ratio, which is a value obtained by dividing by the density difference in the reproduced image, and outputs the calculation result of the white streak contrast ratio.
In the image forming apparatus of the present invention (A 5 ), in the image forming apparatus of the above invention A4, when the white streak contrast ratio is smaller than 1, the cause of white streak generation is the image holding means. When the white streak contrast ratio is larger than 1, it is presumed that the cause of the white streak is in the developing means, and when the white streak contrast ratio is 1, the cause of the white streak is the above. It is presumed to be other than the image holding means and the developing means, and the estimated result is output.

According to the image forming apparatus of the above invention A1, when an abnormal image of white streaks is generated, the cause of the white streaks is developed and formed by a developing means supplied with a development bias voltage on which AC is superimposed. Easily estimated compared to the case where it is not estimated from the result of the white streak reproduction image of 1 and the second white streak reproduction image formed by developing by a developing means supplied with a development bias voltage in which AC is not superimposed. can do. Further, in the image forming apparatus of the invention A1, the cause of the occurrence of white streaks can be estimated by comparing the output first white streak reproduction image and the second white streak reproduction image.

In the image forming apparatus of the invention A2, the cause of white streak generation can be estimated by looking at the measurement result of the density of the white streak portion in the first white streak reproduction image and the second white streak reproduction image. can.
In the image forming apparatus of the above invention A3, it is possible to know the cause of the occurrence of white streaks by looking at the output estimation result .

In the image forming apparatus of the invention A4, the cause of white streaks can be estimated by looking at the result of the output white streaks contrast ratio.
In the image forming apparatus of the above invention A5, it is possible to know the cause of the occurrence of white streaks by looking at the output estimation result.

It is a schematic diagram which shows the structure of the image forming apparatus which concerns on Embodiment 1 and the like. It is a schematic diagram which shows the configuration of the image forming apparatus in the image forming apparatus of FIG. 1 in an enlarged manner. It is a block diagram which shows the structure of a part (output means, etc.) of the control system in the image forming apparatus of FIG. It is a schematic diagram which shows an example of the white streak reproduction image when the cause of white streak generation is an image holder, (a) shows the 1st white streak reproduction image, (b) is the 2nd white streak. The reproduced image is shown. It is a schematic diagram which shows an example of the white streak reproduction image when the cause of white streak generation is in a developing apparatus, (a) shows the 1st white streak reproduction image, (b) is the 2nd white streak reproduction. The image is shown. It is a schematic diagram which shows an example of the white streak reproduction image when the cause of white streak generation is other than image holding means and development means, (a) shows the 1st white streak reproduction image, (b) is the 1st. The white streak reproduction image of 2 is shown. It is a block diagram which shows the structure of a part (output means, etc.) of the control system in the image forming apparatus which concerns on Embodiment 2. FIG. It is a conceptual diagram which shows the structural example of the concentration measuring means. (A) is a schematic diagram showing a configuration regarding density measurement of a white streak portion in each white streak reproduction image, and (b) is a diagram showing an example of the measurement result of (a). (A) is a conceptual diagram showing a configuration example in which a concentration measurement result is displayed and output, and (b) is a conceptual diagram showing a configuration example in which a concentration measurement result is formed on a recording sheet and output. It is a block diagram which shows the structure of a part (output means, etc.) of the control system in the image forming apparatus which concerns on Embodiment 3. FIG. It is a flowchart which shows the operation content of the output means of FIG. It is a conceptual diagram which shows the configuration example which displays and outputs the estimation result of the white streak occurrence cause. It is a block diagram which shows the structure of a part (output means, etc.) of the control system in the image forming apparatus which concerns on Embodiment 4. FIG. It is a flowchart which shows the operation content of the output means of FIG. (A) is a schematic diagram showing a configuration relating to density measurement of an image portion and a white streak portion in each white streak reproduction image, and (b) is a diagram showing an example of the measurement result of (a). It is a conceptual diagram which shows the structural example which displays and outputs the calculation result of the white streak contrast ratio. (A) is a graph showing an example of the measurement result of the density difference (line contrast) when the cause of white streaks is in the image holding means, and (b) is the density difference (line) when the cause of white streaks is in the developing means. It is a graph which shows the measurement result example of (contrast). It is a graph which also shows a part of the measurement result about the density difference of FIG. (A) is a graph showing the relationship between the density and the white streak contrast ratio when the cause of white streak is in the image holding means, and (b) is the density and the white streak contrast when the cause of white streak is in the developing means. It is a graph which shows the relationship with a ratio. It is a block diagram which shows the structure of a part (output means, etc.) of the control system in the image forming apparatus which concerns on Embodiment 5. It is a flowchart which shows the operation content of the output means of FIG. It is a schematic diagram which shows the formation mechanism of the presumed white streak reproduction image when the cause of white streak generation is the image holding means, (a) shows the case of the first white streak reproduction image, (b) is The case of the second white streak reproduction image is shown. It is a schematic diagram which shows the formation mechanism of the presumed white streak reproduction image when the cause of white streak generation is in the developing means, (a) shows the case of the first white streak reproduction image, (b) is the The case of the second white streak reproduction image is shown.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

[Embodiment 1]
1 to 3 show the image forming apparatus 1 according to the first embodiment. FIG. 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 adopts an electrophotographic method and finally forms an image composed of toner on a recording sheet 9 which is an example of a recording medium based on image information consisting of characters, photographs, figures and the like. be.
Then, as shown in FIG. 1, the image forming apparatus 1 has a housing 10 having a box-shaped appearance as a whole, and the inside of the housing 10 is composed of toner as a developer. An intermediate transfer device 20 that forms a toner image and an intermediate transfer device 30 that holds the toner image formed by the image forming device 20 by primary transfer and then transfers the toner image to a secondary transfer position for secondary transfer to recording paper 9. The feeding device 40 that accommodates and supplies the recording paper 9 to be supplied to the secondary transfer position of the transfer device 30, and the fixing device 50 that fixes the toner image secondarily transferred by the intermediate transfer device 30 to the recording paper 9 and the like. Have been placed.
The housing 10 is formed with a support structure portion and an exterior portion using, for example, materials such as a support member and an exterior material. The alternate long and short dash line shown in FIG. 1 is the main transport path of the recording paper 9 inside the housing 10.

Further, the image forming apparatus 1 includes an operation display device 14 having an input unit 14a for inputting instructions and conditions related to the operation of the image forming apparatus 1 and a display unit 14b for displaying various information such as operation conditions and states. A central control device 60 or the like that collectively controls the operation of the entire image forming apparatus 1 (such as the above-mentioned devices) is also arranged.
Further, the image forming apparatus 1 has a function of estimating the cause of white streaks, as will be described later.

The image forming apparatus 20 includes four image forming apparatus 20Y, 20M, which individually form four color developer (toner) images of yellow (Y), magenta (M), cyan (C), and black (K). It is configured using 20C and 20K.
As shown in FIGS. 1 and 2, each of the image forming apparatus 20 (Y, M, C, K) includes a photosensitive drum 21 which is an example of an image holding means which 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 arranged around each photosensitive drum 21.

Of these, the photosensitive drum 21 forms, for example, an image forming surface (image forming range) having a photodielectric layer (photosensitive layer) made of a photosensitive material on the peripheral surface of a cylindrical or columnar conductive base material to be grounded. It is a photoconductor in the form of a drum. The photosensitive drum 21 is provided so as to receive power from a rotation drive device (not shown) and rotationally drive in the direction indicated by the arrow A.
The charging device 22 is, for example, a contact-type charging device provided with a charging roll 221 that is arranged in a state of being driven to rotate in contact with the image forming surface of the photosensitive drum 21 and to which a required charging voltage is supplied.

The exposure apparatus 23 is an example of an exposure means, and is, for example, a non-scanning exposure apparatus configured by using a light emitting diode and an optical component, or a non-scanning exposure apparatus configured by using an optical component such as a semiconductor laser and a polygon mirror. Scanning type exposure equipment is applied. In the exposure device 23, image information input from the outside through a communication means, a reading device, etc. and image information stored in an internal storage unit are subjected to necessary processing by an image processing device (not shown), and then each color component ( It is input as an image signal decomposed into Y, M, C, K). The exposure apparatus 23 performs exposure according to the input image signal.
The developing device 24 is an example of developing means, and is, for example, a developing device 24 (Y) that uses a two-component developer containing toner of any one of the four colors (Y, M, C, K) and a magnetic carrier. , M, C, K) applies. This developing device 24 (Y, M, C, K) is used, for example, to charge the toner to a negative polarity to perform reverse development. Further, the developing apparatus 24 (Y, M, C, K) includes a developing roll 241 or the like that rotates so as to hold the two-component developer housed in the housing and convey it to the developing region facing the photosensitive drum 21. ing. A development bias voltage in which an AC component is superimposed on a DC component is usually supplied to the development roll 241 with the photosensitive drum 21.

The primary transfer device 25 is an example of the transfer means, and is arranged so as to be in contact with the image forming surface portion (via the intermediate transfer belt 31 described later) as the primary transfer position of the photosensitive drum 21 and to rotate in a driven manner. A contact-type transfer device equipped with a primary transfer roll to which the required primary transfer voltage is supplied is applied.
The drum cleaning device 26 is arranged so as to be in contact with at least the image forming surface portion of the photosensitive drum 21 after the primary transfer at the opening for cleaning work of the housing, and scrapes unnecessary substances such as residual toner on the image forming surface. It is equipped with a cleaning member such as an elastic plate to be removed.
The static eliminator 27 is for, for example, removing static electricity (disappearing of electric charge) by exposing the image forming surface of the photosensitive drum 21 so that the surface potential becomes almost zero.

The intermediate transfer device 30 is arranged at a position on the lower side of the four image drawing devices 20 (Y, M, C, K).
The intermediate transfer device 30 is arranged so as to rotate in the direction indicated by the arrow B while passing through the primary transfer positions facing the primary transfer device 25 of the photosensitive drum 21 in the image drawing device 20 (Y, M, C, K). The intermediate transfer belt 31 is provided as an example of the transfer means.
The intermediate transfer belt 31 is formed into an endless belt having a required thickness and an electric resistance value by using a material in which a resistance adjusting agent such as carbon is dispersed in a substrate such as a polyimide resin or a polyamide resin. be.
Further, the intermediate transfer belt 31 is rotatably supported by being hung on a plurality of support rolls 32a to 32e. The support roll 32a serves as a drive roll, the support roll 32b cooperates with the drive roll 32a to hold the intermediate transfer belt 31 so that a primary transfer surface is formed, and the support roll 32c tensions 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 as a tension applying and meandering correction roll that is applied and corrects the meandering of the intermediate transfer belt 31.

Further, the intermediate transfer device 30 is an example of a transfer means for secondary transfer of the toner image transferred on the intermediate transfer belt 31 to the recording paper 9, and an image on the outer peripheral surface of the intermediate transfer belt 31. It is provided with a belt cleaning device 36 or the like that removes and cleans unnecessary substances such as toner that stays on the holding surface and adheres to the holding surface.
The secondary transfer device 35 includes, for example, a contact member such as a secondary transfer roll that is arranged so as to be in contact with an image holding surface portion supported by the secondary transfer backup roll 32d of the intermediate transfer belt 31 and to be driven to rotate. A contact type transfer device is adopted. Further, 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 arranged so as to come into contact with at least the image holding surface portion of the intermediate transfer belt 31 after the secondary transfer at the opening for cleaning work of the housing, and unnecessary substances such as residual toner on the image holding surface. It is equipped with a cleaning member such as an elastic plate for scraping and cleaning.

The paper feeding device 40 is arranged at a position on the lower side of the intermediate transfer device 30.
The paper feed device 40 has an accommodating body 41 that is freely attached to the housing 10 and is accommodated in a state in which recording sheets 9 of a desired size, type, etc. are stacked on a loading plate (not shown). It is provided with a delivery device 42 that sends out the recording sheets 9 one by one from the housing 41 toward the supply transport path (Rt1) described later. The number of the housing 41 and the sending device 42 is increased or decreased as necessary.
Further, the paper feed device 40 manually feeds the recording paper 9 from a paper feed tray (not shown) used in a state of being open to the outside of the housing 10 so as to join the recording paper 9 into a middle portion of the supply transport path (Rt1). It has a mechanism.
The recording paper 9 can be applied as long as it is a recording medium that can be conveyed by a transport path in the housing 10 and can transfer and fix a toner image. For example, recording cut to a predetermined size can be applied. In addition to paper, thick paper such as postcards and special media such as envelopes can also be used.

The fixing device 50 is arranged at a position on the lower side of the intermediate transfer device 30.
In this fixing device 50, a rotating body 52 for heating, a rotating body 53 for pressurization, and the like are installed inside a housing 51 in which the introduction port 51a and the discharge port 51b of the recording paper 9 are formed. The rotating body 52 for heating is a structure in the form of a roll, a belt, a belt pad, or the like that rotates in the direction indicated by the arrow and is heated by the heating means so that the surface temperature is maintained at a predetermined temperature. The pressurizing rotating body 53 is a structure having a form such as a roll, a belt, a belt pad, etc., which is in contact with a predetermined pressure in a state substantially along the axial direction of the heating rotating body 52 and is driven to rotate. Further, in the fixing device 50, the portion where the rotating body 52 for heating and the rotating body 53 for pressurization come into contact with each other is a fixing process (heating and pressurization) in which a recording paper 9 for holding a toner image is introduced. It is organized as a part.

Further, the image forming apparatus 1 has a supply transport path Rt1 connecting between the paper feed device 40 and the intermediate transfer device 30 as a main paper transport path inside the housing 10, and a secondary transfer position of the intermediate transfer device 30. A relay transfer path Rt2 connecting the fixing device 50 and the paper ejection transfer port Rt3 connecting the fixing device 50 and the paper ejection port 11 of the housing 10 is provided.
The supply transport path Rt1 is a transport path for transporting and supplying the recording paper 9 sent out from the paper feed device 40 to the secondary transfer position of the intermediate transfer device 30, and is not shown as a plurality of paper transport roll pairs 45a to 45d. It is composed of a plurality of paper guide members and the like. The paper transport roll pair 45d is configured as a so-called receipt roll pair that adjusts the timing and the like when supplying the recording paper 9 to the secondary transfer position. The relay transport path Rt2 is a transport path for transporting the recording paper 9 after the secondary transfer to the fixing device 50, and is composed of, for example, a suction type belt transport device 46. The paper discharge transport path Rt3 is a transport path for transporting the recording paper 9 on which the image is formed after fixing so as to be discharged to the discharge storage unit 12, and is a paper guide member (not shown) with a plurality of discharge roll pairs 47a, 47b and the like. It is configured.

<Image forming operation of image forming apparatus>
In this image forming apparatus 1, the basic image forming operation described below is performed. Here, an operation in the case of forming a full-color image composed 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 control device 60 receives a request command for an image forming operation from the outside or the like, in each of the four image forming apparatus 20 (Y, M, C, K), each photosensitive drum 21 has an arrow A. Each of the charging devices 22 is rotated in the direction indicated by the above, and each charging device 22 receives 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 (for example, a negative polarity) and a potential, respectively.
Subsequently, each exposure apparatus 23 exposes the image-forming surface of each photosensitive drum 21 after charging according to the image signals decomposed into each color component (Y, M, C, K). As a result, 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 241. At the same time, the developing electric field formed between the developing roll 241 and the photosensitive drum 21 by receiving the supply of the developing bias voltage electrostatically applies to the electrostatic latent image portion of each color component on the image forming surface of the photosensitive drum 21. Attach each. As a result, toner images of the corresponding colors of 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 receives the supply of the primary transfer voltage to form a primary transfer electric field with the photosensitive drum 21, so that the toner image on each photosensitive drum 21 is transferred to the intermediate transfer belt in the intermediate transfer device 30. The primary transfer is performed in order (in the order of Y, M, C, K) with respect to the image holding surface of 31. Further, 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 eliminates static electricity on the image forming surface of each photosensitive drum 21 after the primary transfer, and prepares 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, so that 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 feed device 40, the paper feed device 42 sends the required recording paper 9 from the accommodating body 41 to the supply transfer path Rt1 and then feeds the required recording paper 9 to the secondary transfer position of the intermediate transfer device 30 via the supply transfer path Rt1. Supply. Then, 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 with the intermediate transfer belt 31, so that the four colors on the intermediate transfer belt 31 are formed. The toner image of the above 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 transferred to the fixing device 50 via the relay transfer path Rt2 after being peeled off from the intermediate transfer belt 31. In the fixing device 50, the recording paper 9 is heated and pressurized when it is introduced into a fixing processing portion which is a contact portion between the heating rotating body 52 and the pressing rotating body 53 and passes therethrough. As a result, the toner constituting the toner image on the recording paper 9 is melted under pressure, and the toner image is fixed on the recording paper 9.
Subsequently, the recording paper 9 after the toner image is fixed is discharged from the housing 51 of the fixing device 50, then transported via the paper discharge transport path Rt3, and finally passes through the paper discharge port 11. By being discharged to the outside of the housing 10, it is housed 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. Further, when a request command for a plurality of image forming operations is received, the above image forming operation is similarly repeated for the number of images.

In addition, in the image forming apparatus 1, in the above-mentioned image forming operation, a monochromatic image is formed by operating any one of the four image forming apparatus 20 (Y, M, C, K), and 4 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.

<Estimation function of the cause of white streaks>
The image forming apparatus 1 has the following configuration as a function of estimating the cause of the occurrence of the white streaks when the image of the white streaks is generated.
That is, as shown in FIGS. 3 to 6 and the like, the image forming apparatus 1 develops the electrostatic latent image formed on the photosensitive drum 21 by the developing apparatus 24 to which the developing bias voltage on which the AC is superimposed is supplied. The white streak reproduction image RG1 of 1 is formed, and the electrostatic latent image formed on the photosensitive drum 21 is developed by the developing apparatus 24 supplied with the development bias voltage to which the AC is not superimposed, and the second white streak reproduction image RG2 is developed. It is configured to include a forming means 61 for forming the above and an output means 70A for outputting information regarding the result of the forming means 61.
Here, the white streaks are the portions of the image portion where the amount of the developer adhered is less than the originally required amount, and finally the background (white) of the transfer destination recording paper 9 is conveyed to the recording paper 9. It is visible as a streak-like abnormal image extending along the direction.

The forming means 61 is composed of an arithmetic processing unit, a storage element, an input / output device, an external storage device, and the like. Further, the forming means 61 is adapted to execute a required control operation based on, for example, a program and data stored in the storage element (ROM or the like), and particularly in the first embodiment, at least the first one is described above. It is configured to be able to perform an image forming operation for forming the white streak reproduction image RG1 and the second white streak reproduction image RG2. The forming means 61 is configured as a part that performs a part of the control function of the central control device 60, but may be configured as an independent control means separate from the central control device 60.

As shown in FIG. 3, the forming means 61 includes a feeding means 15, an exposure driving unit 16 for driving the exposure device 23, a rotation driving unit 17, and two white streak reproduction images RG1 and RG2 formed by the forming means 61. It is connected to an output means 70A for outputting information regarding the result of the above, a display unit 14b of the operation display device 14, and the like, and particularly transmits a control signal necessary for each operation forming the above two white streak reproduction images RG1 and RG2. It has become like.
The feeding means 15 transfers the charging voltage to the charging roll 221 of the charging device 22, the development bias voltage to the development roll 241 of the developing device 24, the primary transfer voltage to the primary transfer device 25, and the secondary transfer voltage to the secondary transfer device 35. Is a means capable of supplying a heating voltage to the heating means in the heating roll 52 of the fixing device 40 at a required time and in a required magnitude.
The rotation drive unit 17 is a rotation member such as a photosensitive drum 21 in the image drawing device 20 (Y, M, C, K), a rotation member such as a development roll 241 in the development device 24, and rotation of a drive roll or the like in the intermediate transfer device 30. It is a means including a member, a rotating member such as a sending device 42 in the feeding device 40, an electric motor that generates and transmits rotational power to a rotating member such as a heating roll 52 of the fixing device 50, and a rotation transmission mechanism.

Further, the forming means 61 is also connected to a communication unit 19 that communicates information with an external device or the like, an input unit 14a of the operation display device 14, and the like, thereby obtaining information necessary for control operation. There is.

Then, when the forming means 61 operates to form the two white streak reproduction images RG1 and RG2, the white streak reproduction images RG1 and RG2 are formed by exposing the image forming surface of the photosensitive drum 21 from the exposure device 23. It is mainly performed to form an electrostatic latent image for processing, and to switch between a development bias voltage on which alternating current is superimposed and a development bias voltage on which alternating current is not superimposed and supply them to the developing apparatus 24, respectively, and other than that, it is normal. It is configured to perform the same operation as the image forming operation.

The electrostatic latent image for forming the white streaks reproduction images RG1 and RG2 is not particularly limited as long as it is a latent image having contents that the white streaks can be easily reproduced. For example, a halftone latent image (image). A latent image whose area ratio is set to about 25 to 80%) is applied.

As the development bias voltage supplied to the developing device 24 when forming the white streak reproduction images RG1 and RG2, basically the development bias voltage supplied during normal image formation operation is applied, and the development bias is applied. Of the voltages, two types are used: a normal development bias voltage in which the DC component is commonly used and the AC component is superimposed as it is, and a special development bias voltage in which the AC component is not superimposed. Therefore, as for the DC component, the same conditions are applied to any development bias voltage.

Further, the forming operation of the white streak reproduction images RG1 and RG2 by the forming means 61 responds to the communication after receiving a notification from the user or the like of the image forming apparatus 1 that an abnormal image of the white streaks has occurred, for example. The service engineer (service man) who rushes to the operation display device 14 is configured to execute the operation when the execution mode of the white streak reproduction image forming operation is selected and instructed from the input unit 14a of the operation display device 14.
In this case, the execution mode of the white streak reproduction image forming operation is displayed as a screen for selection instruction on the display unit 14b of the operation display device 14, and is executed by an arbitrary selection operation. Further, the execution mode of the white streak reproduction image forming operation is configured so that the general user of the image forming apparatus 1 can select and instruct from the display unit 14b of the operation display device 14 based on the information such as the instruction manual. It may be the one that has been done.

The output means 70A transfers (records), for example, a developer image (unfixed toner image) formed on the photosensitive drum 21 by the forming operation of the white streak reproduction images RG1 and RG2 onto the recording paper 9 and outputs the image. It is configured as.

The output means 70A having this configuration has two white streak reproduction images RG1 and RG2 formed as developer images for the white streak reproduction image forming operation executed by the forming means 61. It is realized by proceeding under the same conditions as the image forming operation when forming a normal image, except that the RG2 is transferred to different recording sheets 9 and fixed. The size of the electrostatic latent image for forming each white streak reproduction image RG1 and RG2 and the size of the recording paper 9 on which the toner image of each image is transferred are recorded when the occurrence of white streaks is discovered. It is possible to adopt the same size as the size of the paper 9, but it is also possible to adopt a size smaller than or larger than that.
Then, in the case of the output means 70A, information (white streak reproduction images RG1, RG2 itself) regarding the result of the white streak reproduction image forming operation (white streak reproduction image RG1, RG2) is recorded on the recording paper 9 and obtained. become. Further, such an output means 70A is configured as a part that performs a part of the control function of the central control device 60 or the forming means 61, but may be configured as an independent part.

<Formation of white streak reproduction image>
In the image forming apparatus 1, when the service engineer selects and instructs the execution mode of the white streak reproduction image forming operation from the input unit 14a of the operation display device 14, the forming means 61 executes the following operations.

The white streak reproduction 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, as a representative, the operation contents when the image forming apparatus 20K of the black color K (black) is operated to execute the formation operation of the white streak reproduction image will be described.

First, when the forming means 61 receives a start command regarding the forming operation of the white streak reproduction image, the image forming device 20, the intermediate transfer device 30, the paper feeding device 40, and the fixing device 50 necessary for the forming operation of the white streak reproduction image are received. The required voltage starts to be supplied from the power feeding means 15 and the like, and the required rotational power starts to be transmitted from the rotary drive unit 17.

Then, in the image forming apparatus 20K in which the white streak reproduction image is actually imaged, the image forming surface of the rotating photosensitive drum 21 is controlled by the forming means 61 to have the same charging potential as when the normal image is formed by the charging apparatus 22. After being charged to become It is formed.
Next, in the developing apparatus 24K, under the control of the forming means 61, while the electrostatic latent image for forming the first white streak reproduction image RG1 passes (during the developing step), the normal developing bias on which the AC is superimposed is superimposed. A voltage is supplied to perform development, and a special development bias voltage is supplied to which no AC is superimposed while the electrostatic latent image for forming the second white streak reproduction image RG2 passes, and development is performed. ..

At this time, the photosensitive drum 21 in the image forming apparatus 20K has an electrostatic latent image for forming the first white streak reproduction image RG1 and a static image for forming the second white streak reproduction image RG2 on the image forming surface. Electro-latent images are sequentially formed. After that, in the photosensitive drum 21, the image forming surface portion on which the electrostatic latent image for forming the first white streak reproduction image RG1 was formed was developed to which a normal development bias voltage on which an alternating current was superimposed was supplied. After passing facing the developing roll 241 of the apparatus 24K, a special developing bias voltage in which the image morphological surface portion on which the electrostatic latent image for forming the second white streak reproduction image RG2 is formed is not superposed with AC is applied. It will pass by facing the developing roll 241 of the supplied developing device 24K.

As a result, a developing electric field including an alternating electric field due to an AC component is generated between the photosensitive drum 21 and the developing roll 241 based on the supply of a normal developing bias voltage, and then DC is applied based on the supply of a special developing bias voltage. A developing electric field is formed only by the components, and the developing operation of each of the electrostatic latent images is executed by each developing electric field.
As a result, on the image forming surface of the photosensitive drum 21, a first toner image that becomes the first white streak reproduction image RG1 to which black toner is adhered by development and a second toner image that becomes the second white streak reproduction image RG2 are formed. Are sequentially formed. At this time, the first toner image and the second toner image include white streaks that are almost the same as the found white streaks due to the cause of the occurrence, and as will be described later, the cause of the occurrence of the white streaks. The effect of the difference will appear.

Subsequently, the black first toner image that becomes the first white streak reproduction image RG1 and the black second toner image that becomes the second white streak reproduction image RG2 formed on the photosensitive drum 21 are the black second toner image of the intermediate transfer device 30. After being sequentially transferred and conveyed to the intermediate transfer belt 31, the secondary transfer is sequentially performed on the recording paper 9 at the secondary transfer position in the intermediate transfer device 30. At this time, the first toner image and the second toner image are transferred side by side on one recording sheet 9 according to the size at the time of formation or the like, or if that is not possible, two recording sheets are transferred. Transferred individually to 9.
Finally, the black first toner image and the second toner image are fixed on one or two recording sheets 9 by the fixing device 50, and then recorded on the recording sheet 9 in the discharge accommodating section 12. It is output.

As a result, the white streak reproduction image forming operation by the operation of the image forming apparatus 20K is completed.
Further, in the white streak reproduction image forming operation, after the operation process by operating the black image forming device 20K is completed, the image forming devices 20 (Y, M, C) of the remaining colors are sequentially operated independently. It is executed in the same way.

<Estimation of the cause of white streaks>
When the white streak reproduction image forming operation is performed, two white streak reproduction images RG1 and RG2 are formed and output on one or two recording sheets 9 as information regarding the result of the forming means 61.
In this case, the service engineer compares and examines the two white streak reproduction images RG1 and RG2 (actually, the density of the white streak portion) formed on the recording sheet 9, and the cause of the white streak is as follows. Can be estimated as. At this time, it is possible to visually compare the concentrations of the white streaks with the naked eye, but from the viewpoint of more reliable identification, it is preferable to use a magnifying glass such as a loupe together.

First, as illustrated in FIG. 4, a pattern in which the density of the white streak portion WSa2 in the second white streak reproduction image RG2 appears to be higher than the density of the white streak portion WSa1 in the first white streak reproduction image RG1 (first). In the case of 1 pattern), it is presumed that the cause of the white streaks is the photosensitive drum 21.
Further, as illustrated in FIG. 5, a pattern in which the density of the white streak portion WSb2 in the second white streak reproduction image RG2 appears to be lower than the density of the white streak portion WSb1 in the first white streak reproduction image RG1 ( In the case of the second pattern), it is presumed that the cause of the white streaks is the developing device 24.
Further, as illustrated in FIG. 6, a pattern in which the density of the white streak portion WSc2 in the second white streak reproduction image RG2 appears to be the same level as the density of the white streak portion WSc1 in the first white streak reproduction image RG1. In the case of (third pattern), it is presumed that the cause of the white streaks is neither the photosensitive drum 21 nor the developing device 24.

In this way, the cause of white streak generation is estimated from the shading relationship of the concentrations of the white streak portions WS1 and WS2 in the two white streak reproduction images RG1 and RG2 for the following reasons.

(In the case of pattern 1 above)
First, according to the research by the inventors of the present invention, elements that cause white streaks on the photosensitive drum 21, for example, streaky scratches (including wear) extending in the rotation direction A on the image forming surface and toner components. When there is a first defective portion composed of an adhesive film (so-called filming phenomenon) of (mainly an external additive), the white streak portion in the second white streak reproduction image RG2 is illustrated as shown in FIG. It was found that the result that the density of WSa2 seems to be higher than the density of the white streak portion WSa1 in the first white streak reproduction image RG1 tends to be obtained (the first pattern is obtained).
It is presumed that the causal relationship at this time is established for the following reasons.

That is, when the first defective portion (particularly the streaky scratch) is present on the image forming surface of the photosensitive drum 21, when the image forming surface of the photosensitive drum 21 is charged as illustrated in FIG. 23. A portion consisting of a charge defect potential Vhx (<Vh) whose potential is relatively lower than the (for example, negative) normal charge potential Vh is generated in the portion corresponding to the defect portion. If the first defective portion (particularly, the streak-like scratches or the adhesion film of the toner component) is present on the image-forming surface of the photosensitive drum 21, the charged image-forming surface of the photosensitive drum 21 is exposed to light. When an electrostatic latent image for halftone is formed, a portion of the image forming surface corresponding to the defective portion is composed of a latent image defective potential Vix whose potential is relatively smaller than the normal latent image potential Vi. Occurs. Reference numeral Vd in FIG. 23 indicates a development potential determined by a DC component in the development bias voltage.

Then, when the electrostatic latent image formed on the photosensitive drum 21 in which the defective portion is present is developed by the developing apparatus 24 to which a normal developing bias voltage in which alternating current is superimposed is supplied (at the time of AC-ON), FIG. 23 As illustrated in (a), since an alternating magnetic field AEF is generated between the developing apparatus 24 and the photosensitive drum 21 by an AC component, the developer layer 8a held on the developing roll 241 of the developing apparatus 24 The toner is actively reciprocated with the photosensitive drum 21.
As a result, an amount of toner corresponding to the potential difference (contrast potential) between the developing potential Vd and the normal latent image potential Vi adheres to the portion of the image forming surface excluding the defective portion of the photosensitive drum 21. On the other hand, the toner hardly adheres to the portion of the image forming surface corresponding to the defective portion of the photosensitive drum 21 in response to the relatively small contrast potential due to the latent image defective potential Vix.
As a result, as illustrated in FIG. 23A, the first white streak reproduction image RG1 is formed on the image forming surface of the photosensitive drum 21 in which the portion where the toner hardly adheres is reproduced as the white streak WSa1.
In the portion where the white streaks become WSa1, the toner of the developer layer 8a held on the developing roll 241 is finally returned to the developing roll 241 side while the toner of the developer layer 8a held on the developing roll 241 is reciprocated by the alternating magnetic field AEF, but the contrast potential is reached. There may be a small amount of toner adhering to the amount of toner that is present.

Further, when developing is performed by the developing apparatus 24 supplied with a special developing bias voltage that does not superimpose alternating current on the electrostatic latent image formed on the photosensitive drum 21 in which the defective portion is present (at the time of AC-OFF). As illustrated in FIG. 23B, since an alternating magnetic field AEF is not generated between the developing apparatus 24 and the photosensitive drum 21, the developing agent (actually, toner) held in the developing roll 241 of the developing apparatus 24. ) Will not reciprocate with the photosensitive drum 21.
As a result, an amount of toner whose developability is reduced by the amount that the alternating magnetic field AEF is not generated adheres to the portion of the image forming surface of the photosensitive drum 21 excluding the defective portion. On the other hand, a small amount of toner 8b adheres to the portion of the image forming surface corresponding to the defective portion of the photosensitive drum 21, although it is similarly affected by the deterioration of the developability, but the contrast potential is present. do.
As a result, as illustrated in FIG. 23B, a second white streak reproduction image RG2 is formed in which a portion to which a small amount of toner 8b is attached is reproduced as a white streak WSa2.
Since the alternating magnetic field AEF is not generated, the toner 8b attached to the white streaks WSa2 continues to adhere without being returned from the photosensitive drum 21 to the developing roll 241 side.

Therefore, when the photosensitive drum 21 has a cause of white streaks such as the first defective portion, the toner adhesion amount of the white streaks portion WSa2 in the second white streaks reproduction image RG2 is the first white streaks reproduction image. It is relatively larger than the amount of toner adhered to the white streaks portion WSa1 in RG1.
As a result, in this case, the result is obtained that the density of the white streak portion WSa2 in the second white streak reproduction image RG2 seems to be higher than the density of the white streak portion WSa1 in the first white streak reproduction image RG1. It is presumed that (the above pattern 1 is obtained).

(In the case of pattern 2 above)
Next, according to the research by the inventors of the present invention, a regulatory member 242 that regulates an element that causes white streaks in the developing apparatus 24, for example, the amount (layer thickness) of the developing agent held on the developing roll 241. If there is a second defective portion due to clogging due to a developer or the like in a part of the longitudinal direction of the image, as illustrated in FIG. 5, the white streak portion WSa2 in the second white streak reproduction image RG2 It was found that the density tends to be a second pattern that appears to be thinner than the density of the white streak portion WSa1 in the first white streak reproduction image RG1.
It is presumed that the causal relationship at this time is established for the following reasons.

That is, if the developing apparatus 24 has the second defective portion (clogging between the developing roll and the regulating member, etc.), as illustrated in FIG. 24, between the developing roll 241 and the regulating member 242. The portion 241x with the existing clogging Mz is placed in a state where the developer layer 8a to be retained does not exist. On the other hand, in this case, the photosensitive drum 21 is a normal photosensitive drum in which the above-mentioned defective portion does not exist, and the electrostatic latent image for forming the white streak reproduction image is also normally formed by the normal latent image potential Vi. do.

Then, in the case where a normal development bias voltage in which alternating current is superimposed is supplied to the developing apparatus 24 in which the defective portion exists to develop the electrostatic latent image on the photosensitive drum 21 (at the time of AC-ON), FIG. 24 As illustrated in (a), since the alternating magnetic field AEF is similarly generated between the developing device 24 and the photosensitive drum 21, the developer layer 8a held on the developing roll 241 of the developing device 24 The toner is actively reciprocated with the photosensitive drum 21.
As a result, the portion of the photosensitive drum 21 on the image forming surface excluding the portion corresponding to the defective portion of the developing apparatus 24 has an amount corresponding to the contrast potential between the developing potential Vd and the normal latent image potential Vi. Toner adheres. On the other hand, in the portion of the image forming surface corresponding to the defective portion of the developing apparatus 24 of the photosensitive drum 21, the portion 241x (the portion without the developing agent layer) in which the developing agent layer 8a corresponding to the clogged portion of the developing roll 241 does not exist. However, a part of the toner 8c of the developer layer 8a held on the developing roll 241 by the alternating magnetic field AEF moves so as to scatter in the direction J along the rotation axis direction D to some extent. A large amount of toner adheres.
As a result, as illustrated in FIG. 24A, the first white streak reproduction image RG1 is formed on the image forming surface of the photosensitive drum 21 in which the portion where the toner hardly adheres is reproduced as the white streak WSb1.

Further, the case where development is performed by the developing device 24 to which a special development bias voltage that does not superimpose alternating current is supplied to the developing device 24 in which the defective portion exists (at the time of AC-OFF) is exemplified in FIG. 24 (b). As described above, since the alternating magnetic field AEF is not generated between the developing apparatus 24 and the photosensitive drum 21, the developer (actually toner) held in the developing roll 241 of the developing apparatus 24 is between the photosensitive drum 21 and the developing agent (actually, toner). It will not move back and forth.
As a result, the amount of toner on the image forming surface of the photosensitive drum 21 excluding the defective portion in the developing device 24 is reduced by the amount that the alternating magnetic field AEF is not generated as compared with the case of AC-ON. Adheres. On the other hand, since the alternating magnetic field AEF is not generated on the image forming surface portion corresponding to the defective portion of the photosensitive drum 21, a part of the toner 8c of the developer layer 8a held on the developing roll 241 is in the rotation axis direction. Since it does not scatter in the direction J along D, the toner hardly adheres.
As a result, as illustrated in FIG. 24B, a second white streak reproduction image RG2 is formed in which the portion to which the toner hardly adheres is reproduced as the white streak WSa2.

Therefore, when the developing device 24 has a cause of white streaks such as the second defective portion, the toner adhesion amount of the white streaks portion WSa2 in the second white streaks reproduction image RG2 is the first white streaks reproduction image. It is relatively smaller than the amount of toner adhered to the white streaks portion WSa1 in RG1.
As a result, in this case, it is presumed that the density of the white streak portion WSa2 in the second white streak reproduction image RG2 seems to be lower than the density of the white streak portion WSa1 in the first white streak reproduction image RG1. Will be done.

(In the case of pattern 3 above)
Next, according to the research by the inventors of the present invention, when neither the photosensitive drum 21 nor the developing device 24 has an element that causes white streaks, as illustrated in FIG. 6, the first It was found that the density of the white streak portion WSa2 in the white streak reproduction image RG2 of 2 tends to be the third pattern which appears to be the same level as the density of the white streak portion WSa1 in the first white streak reproduction image RG1.
Incidentally, in this case, it is highly probable that the cause of the white streaks is, for example, the primary transfer device 25, the secondary transfer device 35, or the fixing device 50. Further, in this case, when the concentrations of the two white streaks portions WSa1 and WSa2 are at the same level only when the white streaks reproduction images RG1 and RG2 of specific colors in the above four colors are formed, the white streaks are formed. It is presumed that the cause of the occurrence of is highly likely to be in the primary transfer device 25 due to factors such as the difference in the primary transfer position.

As described above, in the image forming apparatus 1, when an abnormal image of white streaks occurs, the forming operation of the white streaks reproduction image by the forming means 61 and the output operation by the output means 70A are executed by the instruction operation of the service engineer. The cause of the white streaks can be estimated by comparing the results of the first white streak reproduction image RG1 and the second white streak reproduction image RG2 formed and output on the recording sheet 9.
Therefore, when an abnormality occurs in the white streaks, the service engineer can efficiently deal with it by performing necessary repair work and parts replacement work after confirming the object of the estimated cause of the abnormality. As a result, when an abnormality occurs in the white streaks, for example, the service engineer guesses the location where the white streaks occur in the image forming apparatus 1, removes the parts, and observes the actual product, or replaces the same parts with the white streaks. By performing the work of confirming the presence or absence of the occurrence of white streaks, it is not necessary to perform the inefficient work of identifying the cause of the occurrence of the white streaks.

[Embodiment 2]
7 and 8 show the main parts of the image forming apparatus according to the second embodiment. FIG. 7 shows the configuration of the control system in the image forming apparatus, and FIG. 8 shows the configuration of the output means in the image forming apparatus.
The image forming apparatus according to the second embodiment has the same configuration as the image forming apparatus 1 according to the first embodiment except that the output means 70B having a different configuration is applied as the output means in the function of estimating the cause of white streaks. be.

The output means 70B in the image forming apparatus (1) according to the second embodiment is the white streaks portion WS1 and WS2 in the first white streak reproduction image RG1 and the second white streak reproduction image RG2 formed by the forming means 61. It is configured to measure the concentration of and output the measurement result.
As shown in FIG. 7, the output means 70B measures the densities of the white streaks portions WS1 and WS2 in the first white streak reproduction image RG1 and the second white streak reproduction image RG2 recorded on the recording sheet 9. It is provided with a concentration measuring means 73 to be used, and a display output unit 74 for displaying information obtained from the measurement result of the concentration measuring means 73 on the display unit 14b of the operation display device 14.

As shown in FIG. 8, for example, the density measuring means 73 is arranged in the middle of the paper discharge transport path Rt3 between the fixing device 50 and the paper ejection port 11 in the housing 10 of the image forming apparatus. The density measuring means 73 according to the second embodiment includes a density measuring main body 73a arranged on the side facing the surface (image surface) on which the image after fixing is present on the recording paper 9, and the image surface after fixing on the recording paper 9. Is composed of a plate-shaped measurement guide member 73b arranged so as to temporarily support and guide the opposite surface (non-image surface) at the time of measurement of the concentration measurement main body 73a. The density measurement main body 73a is configured to be able to measure the density in the entire width direction orthogonal to the transport direction E of the transport recording sheet 9.

Of these, as the density measuring main body 73a, as illustrated in FIG. 9A, the reading unit for reading the density is along the entire width direction of the maximum width of the recording paper 9 that can be used by the image forming apparatus during transportation. Those having a function of measuring the density of at least the white streaks portions WS1 and WS2 of the white streaks reproduced images RG1 and RG2 existing and formed on the recording paper 9 are used. Further, as the density measurement main body 73a, one capable of measuring the density of the monochromatic toner images of the above four colors (Y, M, C, K) is used.
Incidentally, the density measurement main body 73a measures, for example, the density of the entire surface (including the normal image portion) of each white streak reproduction image RG1 and RG2, and then, from the measured density information, the transport direction E of the recording sheet 9. The measured value of the part where the concentration is relatively thin (the part corresponding to the white streak) is extracted, and the measured value of the extracted part (exists at almost the same position along the transport direction E). (Measured value within the range) is calculated as an average value.
Further, reference numeral SE1 in FIG. 9A indicates a reading region (measurement region) determined as a portion corresponding to a white streak at the time of measurement of the concentration measurement main body 73a. In this measurement region SE1, the central portion of the white streak portion (closer to the center in the width direction orthogonal to the transport direction E) is avoided, in particular, in the white streak reproduction image, avoiding the portion near the boundary with the normal image portion excluding the white streak portion. It is preferable to select the part). This is because, in the portion of the white streaks near the boundary with the image portion, the density of the white streaks is small from the density of the image portion, and it is difficult to obtain a density difference. The position of the white streaks can be almost grasped because the white streaks are reproduced.

<Formation of white streak reproduction image and density measurement>
In the image forming apparatus provided with the output means 70B, as in the case described in the first embodiment, when the forming operation of the white streak reproduction image is executed by the forming means 61, for example, triggered by the instruction operation of the service engineer. , Each white streak reproduction image RG1 and RG2 are formed on the recording paper 9.

Subsequently, the recording paper 9 on which the white streak reproduction images RG1 and RG2 are formed is passed through the density measuring means 73 in the output means 70B in the middle of the paper discharge transport path Rt3, and when passing through the recording paper 9, the drawing shows. As shown in 9, the densities of the white streaks corresponding to the white streaks WS1 and WS2 in the white streaks reproduced images RG1 and RG2 on the recording paper 9 are measured. The measurement result of the concentration is sent to the output means 70B. Further, the recording sheet 9 for which the concentration measurement has been completed is discharged and stored in the discharge accommodating unit 12.

Finally, when the output means 70B receives the measurement results of the densities of the white streaks portions WS1 and WS2 in the white streak reproduction images RG1 and RG2 measured by the density measuring means 73, the display output unit shows the measurement results of the densities. By the operation of 74 or the like, it is displayed on the display unit 14b of the operation display device 14 as illustrated in FIG. 10 (a).

As a result, the service engineer can see the density of the white streak portion WS1 in the first white streak reproduction image RG1 (“○○○” in FIG. 10A) by looking at the display unit 14b of the operation display device 14. The density of the white streak portion WS2 in the second white streak reproduction image RG2 (“Δ△△” in FIG. 10A) can be easily known.

<Estimation of the cause of white streaks>
Then, the service engineer examines the magnitude relationship between the concentrations of the two white streaks WS1 and WS2 from the information on the concentrations of the white streaks WS1 and WS2 in the obtained white streak reproduction images RG1 and RG2. The cause of white streaks can be estimated in the same manner as the estimation in the first embodiment.
That is, when the service engineer finds that the magnitude relationship between the concentrations of the white streaks WS1 and WS2 is "△△△>○○○" (first pattern above) (for example, FIG. 9B), the white streaks are white. It is presumed that the cause of the streaks is the photosensitive drum 21. Further, when the magnitude relationship is the result of "△△△ <○○○" (the second pattern above), it is presumed that the cause of the white streaks is the developing device 24. Further, when the magnitude relationship is the result of "△△△ ≈ ○○○" (the second pattern above), it is presumed that the cause of the white streaks is other than the photosensitive drum 21 and the developing device 24.

In this image forming apparatus, it is possible to adopt a configuration that presents information for collating the magnitude relationship between the concentrations of the white streaks portions WS1 and WS2 with the estimated contents of the cause of the occurrence of the white streaks. Examples of the configuration include a configuration in which the collated information is displayed and presented on the display unit 14b of the operation display device 14, or is described and presented in the operation manual of the image forming apparatus 1.
Further, the above-mentioned magnitude relation of "≈" means that the measured value of the concentration is completely the same and also includes the case where the difference is about ± 1 to 3%.

[Modified Example of Embodiment 2]
In the second embodiment, for the output means 70B, instead of displaying the information obtained from the measurement result of the concentration measuring means 73 on the display unit 14b of the operation display device 14 (FIG. 10A), FIG. As illustrated in b), the information obtained from the measurement result of the concentration measuring means 73 may be formed on the recording paper 9 as an image and output.

Further, in the second embodiment, if the image forming apparatus 1 is configured as a copying machine for recording (copying) the image information of the original document read by the document reading apparatus on the recording paper 9, the output means 70B is used. Instead of the density measuring means 73 arranged in the housing 10, the document reading device can be applied as the density measuring means.
When this configuration is applied, it is configured so that the following operations and operations are performed.
First, the operation content is explained so that the service engineer reads the recording paper 9 on which the white streak reproduction images RG1 and RG2 are formed and output by the formation operation of the white streak reproduction image by the forming means 61. Present it in writing or display it on the display unit 14b to inform it. Subsequently, the density information included in the image information read by the document reader is sent to the output means 70B to perform a process of extracting the density information of the portions corresponding to the white streaks portions WS1 and WS2. Finally, the display unit 14b of the operation display device 14 is obtained with respect to the measurement result of the density of the white streaks portions WS1 and WS2 in the white streak reproduction images RG1 and RG2 by the operation of the display output unit 74 in the output means 70B. It is displayed on the screen and output, or it is formed as an image on the recording paper 9 and output.

[Embodiment 3]
11 to 13 show the main parts of the image forming apparatus according to the third embodiment. 11 shows a configuration of a control system in the image forming apparatus, FIG. 12 shows an operation example of an output means in the image forming apparatus, and FIG. 13 shows an example of information output by the output means in the image forming apparatus. There is.
As shown in FIG. 11, the image forming apparatus according to the third embodiment is an image forming apparatus according to the second embodiment except that the output means 70C having a different configuration is applied as the output means in the estimation function of the cause of white streaks. It has the same configuration as (1).

The output means 70C in the image forming apparatus according to the third embodiment has the first white streak reproduction image RG1 and the second white streak reproduction image formed by the forming means 61 as in the flow of the operation shown in FIG. After measuring the concentration of each white streak portion WS1 and WS2 in RG2, the cause of white streak generation is estimated from the measurement result, and the estimated result is output.
As shown in FIG. 11, the output means 70C measures the densities of the white streaks portions WS1 and WS2 in the first white streak reproduction image RG1 and the second white streak reproduction image RG2 recorded on the recording sheet 9. The concentration measuring means 73, the concentration acquisition unit 75 that acquires the measurement result of the concentration obtained by the concentration measuring means 73, and the estimation unit 76 that estimates the cause of white streaks from the concentration measurement results in the concentration acquisition unit 75. It is provided with a display output unit 74 for displaying the result estimated by the estimation unit 76 on the display unit 14b of the operation display device 14.

As for the concentration measuring means 73, the concentration measuring means 73 according to the second embodiment is similarly applied. Further, the concentration acquisition unit 75 is configured by a storage means capable of accumulating information regarding the measurement result of the concentration. Further, the estimation unit 76 is based on the information on the concentrations of the white muscle portions WS1 and WS2 in the white muscle reproduction images RG1 and RG2 acquired by the density acquisition unit 75, and the density of the two white muscle portions WS1 and WS2 is large or small. After investigating the relationship, the process of estimating the cause of the occurrence of white streaks in the same manner as the estimation in the first embodiment is performed.

<Formation of white streak reproduction image, density measurement and estimation of white streak generation cause>
In the image forming apparatus provided with the output means 70C, as in the case described in the first embodiment, for example, when an instruction operation by a service engineer is received, the white streaks are reproduced by the forming means 61 as shown in FIG. The image formation operation is executed (step 10: S10). As a result, the white streak reproduction images RG1 and RG2 are formed on the recording sheet 9.

Subsequently, the recording paper 9 on which the white streak reproduction images RG1 and RG2 are formed is passed through the density measuring means 73 in the output means 70B in the middle of the paper discharge transport path Rt3, and the recording paper is passed therethrough. The concentrations D1 and D2 of the white streaks corresponding to the white streaks WS1 and WS2 in the white streak reproduction images RG1 and RG2 on 9 are measured (S11). The measurement results of the concentrations D1 and D2 are sent to the concentration acquisition unit 75 of the output means 70C.

In the output means 70C, when the measurement results of the concentrations D1 and D2 corresponding to the white streaks portions WS1 and WS2 are acquired from the concentration measuring means 73 by the concentration acquisition unit 75, the estimation unit 76 obtains the concentrations related to the white streaks portions WS1 and WS2. After investigating the magnitude relationship of D1 and D2 (S12), the cause of white streaks is estimated as follows (S13, S14 or S15).
That is, in the estimation unit 76, when the density D2 of the white streak portion WS2 in the second white streak reproduction image SG2 is larger (darker) than the density D1 of the white streak portion WS1 in the first white streak reproduction image SG1. (D2> D1), it is presumed that the cause of the white streaks is the photosensitive drum 21 (S13). Further, when the density D2 of the white streaks portion WS2 is smaller (thinner) than the concentration D1 of the white streaks portion WS1 (D2 <D1), it is presumed that the cause of the white streaks is in the developing device 24 ( S14). Further, when the density D2 of the white streaks portion WS2 has almost the same relationship as the density D1 of the white streaks portion WS1 (D2≈D1), it is presumed that the cause of the white streaks is other than the photosensitive drum 21 and the developing device 24. (S15).

Finally, in the output means 70B, the estimation result of the cause of the white streaks obtained by the estimation unit 76 is measured by the operation of the display output unit 74 or the like, for example, as illustrated in FIG. 13, the display unit 14b of the operation display device 14. Is displayed in (S16).

Then, in this case, the service engineer can know the cause of the white streaks by looking at the estimation result automatically displayed and output on the display unit 14b of the operation display device 14.

[Embodiment 4]
14 to 17 show the main parts of the image forming apparatus according to the fourth embodiment. FIG. 14 shows the configuration of the control system in the image forming apparatus, FIG. 15 shows an operation example of the output means in the image forming apparatus, and FIG. 16 shows the configuration regarding the density measurement of the output means in the image forming apparatus. Reference numeral 17 shows an example of information output by the output means in the image forming apparatus.
As shown in FIG. 14, the image forming apparatus according to the fourth embodiment is an image forming apparatus according to the third embodiment except that the output means 70D having a different configuration is applied as the output means in the estimation function of the cause of white streaks. It has the same configuration as (1).

The output means 70D in the image forming apparatus according to the fourth embodiment has each normal image portion (white) in each white streak reproduction image RG1 and RG2 formed by the forming means 61 as in the flow of the operation shown in FIG. Contrast ratios D3 and D4 of the white streaks (excluding the streaks) and concentrations D1 and D2 of the white streaks WS1 and WS2 are measured, and the density difference DS1 (= D3-) between each normal image portion and each white streak WS1 and WS2. It is a value obtained by calculating D1) and DS2 (= D4-D2), respectively, and dividing the density difference DS1 in the second white streak reproduction image RG2 by the density difference DS2 in the first white streak reproduction image RG1. It is configured to calculate a certain white streak contrast ratio SC (= DS1 / DS2) and output the calculation result of the white streak contrast ratio SC.

As shown in FIG. 14, the output means 70D measures the densities of the white streak portions WS1 and WS2 in the first white streak reproduction image RG1 and the second white streak reproduction image RG2 recorded on the recording sheet 9. The white streaks from the concentration difference measuring means 73, the concentration difference calculation unit 77 for calculating the concentration difference DS1 and DS2 from the measurement results of the concentration measuring means 73, and the concentration difference DS1 and DS2 obtained by the concentration difference calculation unit 77. It includes a white streak contrast ratio calculation unit 78 for calculating the contrast ratio SC, and a display output unit 74 for displaying the calculation result of the white streak contrast ratio on the display unit 14b of the operation display device 14.

As for the density measuring means 73, as illustrated in FIG. 16, the density D3 and D4 of each normal image portion (the portion excluding the white streak portion) in each white streak reproduction image RG1 and RG2 are additionally measured. Except for the addition, the concentration measuring means 73 (FIG. 9) in the second embodiment can be similarly applied.
In particular, the density measuring body 73a in the density measuring means 73 measures, for example, the density of the entire surface (including a normal image portion) of each white streak reproduction image RG1 and RG2. Next, from the measured density information, the measured value of the portion where the density existing so as to extend along the transport direction E of the recording paper 9 (the portion corresponding to the white streaks) and the portion where the density is thin are taken. After extracting the measured value of the relatively dark part (normal image part) to be excluded, the measured value of the extracted two parts (measured value within the range existing along the transport direction E at almost the same position). ) Are averaged. Reference numeral SE2 in FIG. 16A indicates a reading area (measurement area) determined as a normal image portion of each white streak reproduction image RG1 and RG2 at the time of measurement of the density measurement main body 73a.

Further, the density difference calculation unit 77 and the white streak contrast ratio SC are configured by arithmetic processing means capable of calculating the density difference DS1 and DS2 and the white streak contrast ratio SC. Incidentally, the density difference DS1 and DS2 between the density of the normal image portion and the density of the white streak portion in the white streak reproduced images RG1 and RG2 are also referred to as line contrast (FIG. 16 (b)).

<Formation of white streak reproduction image, density measurement and contrast ratio calculation>
In the image forming apparatus provided with the output means 70D, as in the case described in the first embodiment, for example, when an instruction operation by a service engineer is received, the white streaks are reproduced by the forming means 61 as shown in FIG. The image formation operation is executed (step 20: S20). As a result, the white streak reproduction images RG1 and RG2 are formed on the recording sheet 9.

Subsequently, the recording paper 9 on which the white streak reproduction images RG1 and RG2 are formed is passed through the concentration measuring means 73 in the output means 70D in the middle of the paper discharge transport path Rt3, and the recording paper is passed therethrough. In each of the white streak reproduction images RG1 and RG2 on 9, the densities D1 and D2 of the portions corresponding to the white streaks portions WS1 and WS2 and the densities D3 and D4 of the normal image portion are measured (S21). The measurement results of the concentrations D1 to D4 are sent to the output means 70D.

Subsequently, in the output means 70D, when the measurement results of the above concentrations D1 to D4 are acquired from the density measuring means 73, the density difference calculation unit 77 sets the density D3 of the normal image portion in the first white streak reproduction image RG1. The density difference DS1 (= D3-D1) between the white streak portion WS1 and the density D1 and the density difference DS2 between the normal image portion density D4 and the white streak portion WS2 density D2 in the second white streak reproduction image RG2 (= D3-D1). = D4-D2) are calculated respectively (S22).

Further, in the output means 70D, in the white streak contrast ratio calculation unit 78, the density difference DS1 in the second white streak reproduction image RG2 obtained by the density difference calculation unit 77 is converted into the density difference in the first white streak reproduction image RG1. The white streak contrast ratio SC (= DS1 / DS2), which is a value obtained by dividing by DS2, is calculated (S23).

Finally, in the output means 70D, the operation display device 14 as illustrated in FIG. 17 shows the calculation result of the white streak contrast ratio SC calculated by the white streak contrast ratio calculation unit 78 by the operation of the display output unit 74 or the like. Is displayed on the display unit 14b of (S24). At this time, the calculation result of the white streak contrast ratio SC is displayed as, for example, a numerical value including a decimal point (0.0 <SC <2.0).

<Estimation of the cause of white streaks>
When the white streak reproduction image is formed according to the fourth embodiment, the white streak contrast ratio SC is displayed and output as information regarding the result of the forming means 61.
In this case, the cause of the occurrence of the white streaks can be estimated as follows by looking at the calculation result (value) of the white streaks contrast ratio SC output by the service engineer.

That is, in the fourth embodiment, when the white streak contrast ratio SC is smaller than 1 (in the case of “SC <1”), it is presumed that the cause of the white streak is the photosensitive drum 21. When the white streak contrast ratio SC is larger than 1 (in the case of "SC> 1"), it is presumed that the cause of the white streak is in the developing device 24. When the white streak contrast ratio SC is approximately 1 (in the case of "SC≈1"), it is presumed that the cause of the white streak is other than the photosensitive drum 21 and the developing device 24.

The cause of the occurrence of white streaks is estimated from the value of the white streaks contrast ratio SC as described above for the following reasons.

First, FIG. 18 shows an example of the result when the line contrast which is the density difference DS1 and DS2 in the white streak reproduction images RG1 and RG2 formed by the forming means 61 is measured.
Of these, FIG. 18A shows test image formation when the developing apparatus 24 has the above-mentioned second defective portion (clogging between the developing roll and the restricting member) corresponding to the cause of white streaks. The result when the device (1) was prepared and the line contrast which is the density difference DS1 and DS2 in the white streak reproduction images RG1 and RG2 formed in the test image forming apparatus was measured is shown. Further, FIG. 18B prepares a test image forming apparatus (1) in the case where the photosensitive drum 21 has the above-mentioned first defective portion (scratch, filming, etc.) corresponding to the cause of white streaks. The results of measuring the line contrast, which is the density difference DS1 and DS2 in the white streak reproduction images RG1 and RG2 formed by the test image forming apparatus, are shown.

In the measurement at this time, each white streak reproduction image RG1 and RG2 are formed on the recording paper 9 and output in each of the test image forming apparatus (1), and each white streak reproduction image RG1 on the recording paper 9 is output. , After measuring the densitometers D3 and D4 of each normal image portion in RG2 and the densitometers D1 and D2 of each white streak portion WS1 and WS2 using a densitometer (X-rite: 404A: color reflection type densitometer). , Each density difference DS1 and DS2 which are line contrasts were calculated.
The original shown in FIG. 18 refers to the case where the alternating current under the conditions (original value) applied during normal image forming operation is applied as the alternating current in the development bias voltage supplied in each of the test image forming apparatus (1). show.
Further, the density adjustment shown in FIG. 18 is changed to a value larger than the amplitude value of the alternating current applied during the normal image forming operation as the alternating current in the development bias voltage supplied in each of the test image forming apparatus (1). The case where the toner is easily transferred from the developing device 24 to the photosensitive drum 21 side and the density is adjusted is shown.

Further, FIG. 19 shows an example of the result in which the measurement result of the line contrast in the case of the “original” shown in FIGS. 18 (a) and 18 (b) is described in the same graph.

From the measurement result examples shown in FIGS. 18 and 19, it can be seen that there is the following tendency.
That is, regarding the line contrast when the developing device 24 has a cause of white streaks, when the alternating current of the developing bias voltage is not superimposed (when AC-OFF), when the alternating current is superimposed (when AC-ON). Tends to show a larger value than. On the other hand, regarding the line contrast when the photosensitive drum 21 has a cause of white streaks, when the alternating current of the development bias voltage is superimposed (when AC-ON), the alternating current is not superimposed (when AC-OFF). Tends to show a larger value than.

This means that the white streak contrast ratio SC (= DS1 / DS2) of the value obtained by dividing the density difference DS1 in the second white streak reproduction image RG2 by the density difference DS2 in the first white streak reproduction image RG1 is obtained. When used, it can be rephrased as having the following tendency.
That is, it can be said that the white streak contrast ratio SC tends to be larger than "1" when the developing device 24 has a cause of white streaks. Further, the white streak contrast ratio SC when the photosensitive drum 21 has a cause of white streak shows some exceptional results (value larger than "1"), but is almost smaller than "1". It can be said that there is a tendency to become. Further, when the white streak contrast ratio SC becomes almost "1" (when the result is such that the scales on the vertical axis and the horizontal axis in FIG. 19 are located on the straight line of the dotted line), the white streaks are not originally present. Although it includes the case of occurrence, it can be said that there is a high possibility that the cause of occurrence of white streaks is not at least either the photosensitive drum 21 or the developing device 24.
From the above, it is estimated as described above by dividing the white streak contrast ratio SC into a value larger than "1", a value smaller than "1", and a value almost "1". ing. In this case, "1" is, for example, in the range of 0.9 to 1.1.

Incidentally, FIG. 20 shows the result of investigating the relationship between the density of the white streak reproduction images RG1 and RG2 and the white streak contrast ratio. FIG. 20 (a) shows the result regarding the white streak contrast ratio when the developing device 24 has the cause of white streak, and FIG. 20 (b) shows the white streak contrast when the photosensitive drum 21 has the cause of white streak. The results regarding the ratio are shown.
Here, the concentration on the horizontal axis in the graph in FIG. 20 is a value measured by the above densitometer.

From the results shown in FIG. 20 (a), it can be seen that the white streak contrast ratio when the developing apparatus 24 has a cause of white streak shows a value larger than "1" regardless of the difference in density. Further, from the results shown in FIG. 20 (b), the white streak contrast ratio when the photosensitive drum 21 has a cause of white streak shows an exceptional value only when the density is the highest. It can be seen that the value is smaller than 1 ”.

As described above, in the image forming apparatus according to the fourth embodiment, when an abnormality of the white streaks occurs, the forming operation of the white streaks reproduction image by the forming means 61 and the output means 70D are triggered by the instruction operation of the service engineer. By executing the output operation, to see the white streak contrast ratio SC output and displayed as information on the results of the first white streak reproduction image RG1 and the second white streak reproduction image RG2 regarding the cause of the white streak generation. Can be estimated with.
Further, in this image forming apparatus, as in the case of the second embodiment, it is possible to adopt a configuration that presents information for collating the white streak contrast ratio SC with the estimated content of the cause of white streak occurrence.

[Embodiment 5]
21 and 22 show the main parts of the image forming apparatus according to the fifth embodiment. FIG. 21 shows the configuration of the control system in the image forming apparatus, and FIG. 22 shows an operation example of the output means in the image forming apparatus.
As shown in FIG. 21, the image forming apparatus according to the fifth embodiment is an image forming apparatus according to the fourth embodiment except that the output means 70E having a different configuration is applied as the output means in the estimation function of the cause of white streaks. It has the same configuration as (1).

As shown in FIG. 22, the output means 70E in the image forming apparatus according to the fifth embodiment performs the same operation as the output means 70D in the fourth embodiment (S20 to S23 in FIG. 15), thereby performing each white streak. After calculating the white streak contrast ratio SC for the reproduced images RG1 and RG2, the cause of white streak generation is estimated from the white streak contrast ratio SC, and the estimated result is output.
Further, as shown in FIG. 21, the output means 70E is the output means 70D in the first white streak reproduction image RG1 and the second white streak reproduction image RG2 recorded on the recording sheet 9 in the fourth embodiment. Similar to the configuration (FIG. 14), in addition to having the density measuring means 73, the density difference calculation unit 77, the white streak contrast ratio calculation unit 78, and the display output unit 74, the white streak contrast ratio SC It includes an estimation unit 79 for estimating the cause of white streaks.

As for the concentration measuring means 73, the concentration measuring means 73 according to the second embodiment is similarly applied. Further, the density difference calculation unit 77 and the white streak contrast ratio calculation unit 78 in the fourth embodiment are similarly applied to the density difference calculation unit 77 and the white streak contrast ratio calculation unit 78. Further, the estimation unit 79 examines the magnitude relationship between the value of the white streak contrast ratio calculated by the white streak contrast ratio calculation unit 78 and "1", and then estimates the cause of the white streak in the fourth embodiment. It performs the estimation process in the same way.

<Formation of white streak reproduction image, calculation of white streak contrast ratio, and estimation of cause of white streak>
In the image forming apparatus provided with the output means 70E, the white streaks are reproduced by the forming means 61 as shown in FIG. 22 when, for example, an instruction operation by a service engineer is received, as in the case described in the first embodiment. The image formation operation is executed (step 30: S30). As a result, the white streak reproduction images RG1 and RG2 are formed on the recording sheet 9.

Subsequently, as shown in FIG. 22, the operation of the concentration measurement by the concentration measuring means 73 (S31) and the calculation of the concentration difference are the same as the operation of the output means 70D in the fourth embodiment (S21 to S23 in FIG. 15). The operation of calculating the density difference DS1 and DS2 by the unit 77 (S32) and the operation of calculating the white streak contrast ratio SC by the white streak contrast ratio calculation unit 78 (S33) are sequentially performed.

In the output means 70E, when the calculation result of the white streak contrast ratio SC is acquired from the white streak contrast ratio calculation unit 78 by the estimation unit 79, the estimation unit 79 determines the magnitude relationship between the value of the white streak contrast ratio SC and “1”. After the investigation (S34), the cause of the white streaks is estimated as follows (S35, S36 or S37).
That is, when the white streak contrast ratio SC is smaller than 1 (SC <1), the estimation unit 79 presumes that the cause of the white streak is the photosensitive drum 21 (S35). Further, when the white streak contrast ratio SC is larger than 1 (SC> 1), it is presumed that the cause of the white streak is in the developing device 24 (S36). Further, when the white streak contrast ratio SC is 1 (SC≈1), it is presumed that the cause of the white streak is other than the photosensitive drum 21 and the developing device 24 (S37).

Finally, in the output means 70E, the estimation result of the cause of the white streaks obtained by the estimation unit 79 is obtained by the operation of the display output unit 74 or the like, for example, as illustrated in FIG. 13, the display unit 14b of the operation display device 14. Is displayed in (S38).

Then, in this case, the service engineer can know the cause of the white streaks by looking at the estimation result automatically displayed and output on the display unit 14b of the operation display device 14.

[Other embodiments]
In the second to fifth embodiments, the output means 70B to 70E display and output the measurement result of the density and the calculation result of the white streak contrast ratio, and the cause of the white streak generation based on the density and the white streak contrast ratio. Although a configuration example in which the estimation result is displayed and output is shown, it is also possible to apply a configuration that outputs differently to the output means 70B to 70E.
As another configuration of the output means 70B to 70E, for example, the measurement result of the density, the calculation result of the white streak contrast ratio, or the estimation result of the cause of the white streak is converted into electronic information, and then the maintenance management of the image forming apparatus is performed. It is configured to send and output to the customer management center that performs such as by communication means. In this case, the customer management center estimates the cause of white streaks and returns the estimation result to the service engineer, or parts and devices that need repair or replacement based on the estimated information on the cause of white streaks. Arrangements for specific delivery can be made.

Further, the image forming apparatus is exemplified in the first to fifth embodiments as long as it is an image forming apparatus including an image holding means such as a photoconductor, a charging means, a latent image forming means such as an exposure device, and a developing means. The image forming apparatus 1 adopting the intermediate transfer method is not limited to this, and other types of image forming apparatus may be used. The image holding means is a member or a structure capable of holding (forming) a latent image and holding a developer image (toner image or the like) after the latent image is developed with a developer.

1 ... Image forming apparatus 14b ... Display unit (example of display means)
21 ... Photosensitive drum (an example of image retention means)
22 ... Charging device (an example of charging means)
23 ... Exposure device (example of latent image forming means)
24 ... Developing device (an example of developing means)
61 ... Forming means 70A to 70E ... Output means RG1 ... First white streak reproduction image RG2 ... Second white streak reproduction image WS1 ... White streak portion WS2 ... Second white streak reproduction image in the first white streak reproduction image White streaks in

Claims (5)

Image retention means,
The charging means for charging the image holding means and the charging means
A latent image forming means for forming an electrostatic latent image on the image holding means,
A developing means that is supplied with a development bias voltage capable of superimposing alternating current between the image holding means and develops the electrostatic latent image on the image holding means with a developer.
The electrostatic latent image formed in the image holding means is developed by the developing means to which the development bias voltage on which the AC is superimposed is supplied to form the first white streak reproduction image, and is formed in the image holding means. A forming means for developing a second white streak reproduction image by developing the electrostatic latent image to be developed by the developing means to which the developing bias voltage to which the AC is not superimposed is supplied.
An output means for outputting information regarding the result of the forming means, and an output means.
Equipped with
The output means is an image forming apparatus that outputs a first white streak reproduction image and a second white streak reproduction image formed by the forming means. The image forming apparatus according to claim 1, wherein the output means outputs a measurement result of the density of each white streak portion in the first white streak reproduction image and the second white streak reproduction image formed by the forming means. In the output means, when the density of the white streak portion in the second white streak reproduction image is darker than the density of the white streak portion in the first white streak reproduction image in the measurement result, the cause of the white streak is generated. It is presumed that it is in the image holding means, and when the measurement result shows that the density of the white streaks in the second white streak reproduction image is lighter than the density of the white streaks in the first white streak reproduction image, it is white. It is presumed that the cause of the streaks is the development means, and in the measurement result, the density of the white streaks in the second white streak reproduction image and the density of the white streaks in the first white streak reproduction image have the same relationship. The image forming apparatus according to claim 2 , wherein it is estimated that the cause of white streaks is other than the image holding means and the developing means, and the estimated result is output . The output means measures the density of each image portion and each white streak portion in the first white streak reproduction image and the second white streak reproduction image formed by the forming means, and the image portion and the white streak portion. And the white streak contrast ratio, which is a value obtained by dividing the density difference in the second white streak reproduction image by the density difference in the first white streak reproduction image, is calculated. The image forming apparatus according to claim 1 , wherein the image forming apparatus is performed and the calculation result of the white streak contrast ratio is output . When the white streak contrast ratio is smaller than 1, the output means presumes that the cause of the white streak is in the image holding means, and when the white streak contrast ratio is larger than 1, the cause of the white streak is generated. Is presumed to be in the developing means, and when the white streak contrast ratio is 1, it is presumed that the cause of the white streaks is other than the image holding means and the developing means, and the estimated result is output. The image forming apparatus according to claim 4 .

Images