JP2011154082A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress image density unevenness in the axial direction of a charging roller, which is caused by a nonuniform quantity of foreign matter adhering to the surface of the charging roller in the axial direction of the charging roller with a lapse of time. <P>SOLUTION: The image forming apparatus includes a sensor unit configured to perform a detecting operation at predetermined detecting timing, the detecting operation being provided to detect the states of a plurality of parts of the surface of the charging roller 5, which are different from one another in position in the widthwise direction of the image part area of the surface of a photoreceptor 3 (in the axial direction of the photoreceptor). Based on the detection results obtained from the plurality of areas detected by the sensor 31 of this sensor unit, a controller corrects the intensity of light emission of each of the LED units of an exposure device 4 so as to decrease potential differences between a plurality of exposure portions different in position in the widthwise direction of the image part area. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to an image forming apparatus that charges a surface of a photoconductor with a charging roller disposed in contact with or close to the surface of the photoconductor.

  In this type of image forming apparatus, an image area (area where an electrostatic latent image can be formed) on a photoreceptor surface is generally charged to a desired uniform potential by a charging roller to which a predetermined charging bias is applied. The image area is irradiated with light to form an electrostatic latent image, and then toner is attached to the electrostatic latent image to form a toner image. Then, the toner image on the photosensitive member formed in this way is transferred onto a recording material via an intermediate transfer member, or directly transferred onto the recording material to form an image based on the toner image on the recording material. To do. In such an image forming apparatus, foreign matter such as toner or paper dust adheres to the surface of the charging roller by performing image formation. When the amount of foreign matter adhering to the surface of the charging roller increases, the charging ability of the charging roller is lowered, and background stains are generated.

2. Description of the Related Art Conventionally, as an image forming apparatus that suppresses such background stains, an apparatus that employs a configuration that cleans the surface of a charging roller as in the image forming apparatus described in Patent Document 1 is known. In such an image forming apparatus, since it is possible to suppress an increase in the amount of foreign matter adhering to the surface of the charging roller, it is possible to suppress a decrease in charging ability of the charging roller and to suppress the occurrence of background stains.
Further, even if a configuration for cleaning the surface of the charging roller is adopted, it is difficult to completely remove the foreign matter on the surface of the charging roller, so the amount of foreign matter adhering to the surface of the charging roller continues to increase over time. For this reason, the charging ability of the charging roller gradually decreases, and background dirt may occur over time. In order to suppress this, in the image forming apparatus described in Patent Document 1, the charging bias applied to the charging roller according to the reflection density on the surface of the photoconductor detected at a specific location (one location) in the photoconductor axial direction. Is corrected. By detecting the reflection density on the surface of the photoreceptor, it is possible to grasp the degree of background contamination due to a decrease in charging ability of the charging roller. Therefore, even if the amount of foreign matter adhering to the surface of the charging roller increases with time and the charging ability of the charging roller decreases, the charging ability of the charging roller can be recovered by correcting the charging bias, thereby improving the charging ability of the charging roller. It can be maintained over time. Therefore, according to the image forming apparatus described in Patent Document 1, the occurrence of background stains can be suppressed for a long time.

  However, in general, in a configuration in which the foreign matter on the surface of the charging roller is removed by some cleaning member, cleaning unevenness occurs in the charging roller axial direction. For example, according to the description in Patent Document 1, in the configuration in which a cleaning member such as a sponge is brought into contact with the surface of the charging roller to remove the foreign matter on the surface of the charging roller, the end region of the charging roller axial direction center region is removed. Since the cleaning capability is low, cleaning unevenness occurs in the charging roller axial direction. If there is uneven cleaning in the charging roller axial direction, the amount of foreign matter adhering to the surface of the charging roller will be biased in the charging roller axial direction over time. For this reason, unevenness in the charging roller axial direction occurs in the charging ability of the charging roller, and charging unevenness in the charging roller axial direction (photosensitive member axial direction) occurs in the image area on the surface of the photosensitive member. In the case where such uneven charging occurs, when an electrostatic latent image is formed with the same amount of light for the image area, the potential of the portion irradiated with light (exposed portion) becomes different according to the uneven charging, Unevenness is caused in the development potential (difference between the exposure portion potential and the development bias). As a result, the amount of toner adhering to the exposed portion becomes uneven, causing a problem of causing image density unevenness in the charging roller axial direction (photoreceptor axial direction).

  Note that this problem is not limited to the configuration in which foreign substances on the surface of the charging roller are removed by some cleaning member. That is, even when such a configuration is not adopted, if the toner image formed on the photosensitive member in the past is biased in the charging roller axial direction (photosensitive member axial direction), foreign matter adhering to the surface of the charging roller The amount is deviated in the axial direction of the charging roller with time. Therefore, the same problem of causing uneven image density in the charging roller axial direction (photosensitive member axial direction) occurs.

  The present invention has been made in view of the above-described problems, and the object of the present invention is to increase the amount of foreign matter adhering to the surface of the charging roller in the charging roller axial direction caused by the deviation in the charging roller axial direction over time. An object of the present invention is to provide an image forming apparatus capable of suppressing image density unevenness.

In order to achieve the above object, the invention according to claim 1 is arranged such that the outer peripheral surface of the charging roller is disposed in contact with or close to the entire width of the image area on the surface of the surface-moving photoconductor. By applying a predetermined charging bias to the roller, the image area on the surface of the photosensitive member is charged to a predetermined potential, and the exposed image area is irradiated with light, and the exposed area irradiated with the light is exposed to an electrostatic latent image. In the image forming apparatus for forming an image on the recording material by attaching toner to the electrostatic latent image and finally transferring the toner image obtained thereby to the recording material, Surface state detection means for performing a detection operation for detecting a surface state at a plurality of locations on the surface of the charging roller or the surface of the photoconductor, the positions of which are different from each other in the region width direction, and the surface state detection means Based on the detected detection results for the plurality of locations, per unit area of the image area on the surface of the photoconductor so that a potential difference between a plurality of exposure sections having different positions in the width direction of the image area is small. And a light amount correction unit that corrects the light amount of the irradiated light.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the surface state detection means includes one or more detection units for detecting the surface state of the charging roller or the photosensitive member. Alternatively, the detection operation is performed while moving in the width direction of the image area so as to face the surface of the photoconductor.
According to a third aspect of the present invention, in the image forming apparatus of the second aspect, the surface state detecting means is a guide provided with a spiral screw groove as a moving means for moving the detecting portion in the width direction of the image area. A means for moving the detecting portion engaged with the screw groove of the guide shaft in the axial direction of the guide shaft by rotating the shaft is used.
According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the charging roller is replaced when the detection result of the surface state detection means exceeds a predetermined allowable range. It is characterized by having a notification processing means for performing a notification process for prompting.
According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the surface state detecting means does not require a predetermined detection from an initial time point when the charging roller is in an unused state. Before the period elapses, the above detection operation is not performed.
According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, an instruction by an operator as to whether or not the surface state detection means is permitted to perform a detection operation. It has an instruction receiving means for receiving, and the surface state detecting means determines whether or not to perform the detection operation according to the instruction content received by the instruction receiving means.

  In the present invention, the surface state is detected at a plurality of locations on the surface of the charging roller or the surface of the photosensitive member having different positions in the image region width direction. The surface state referred to here is the surface state of the charging roller or the photoreceptor having a correlation with the charging ability of the charging roller. In the case of a charging roller, it means a surface state that affects the charging ability of the charging roller, and a specific example is a state of foreign matter adhering on the surface of the charging roller. In the case of a photoconductor, it means a surface state that changes according to the charging ability of the charging roller, and a specific example is the state of the charged potential on the surface of the photoconductor or the state of background contamination. By detecting the surface state at such a plurality of locations, it is possible to grasp the deviation of the charging ability of the charging roller in the image area width direction (charging roller axial direction). As a result, the state of uneven charging on the surface of the photoconductor in the width direction of the image area can be grasped, and thus the amount of light (exposure amount) irradiated per unit area of the image area on the surface of the photoconductor is corrected. Thus, it is possible to reduce the potential difference between a plurality of exposed portions whose positions in the image region width direction are different from each other. If the potential difference between the exposed portions in the image portion region width direction is reduced, the difference in development potential in the image portion region width direction is also reduced, and image density unevenness is reduced.

  As described above, according to the present invention, it is possible to suppress the image density unevenness in the charging roller axial direction caused by the amount of foreign matter adhering to the charging roller surface being deviated in the charging roller axial direction over time. can get.

1 is an explanatory diagram illustrating a schematic configuration of a copier according to an embodiment. 2 is a perspective view schematically showing a sensor device according to Configuration Example 1 used in the copier. FIG. FIG. 3 is a schematic diagram when the sensor device is viewed from the charging roller axial direction. It is the perspective view which showed typically the sensor apparatus which concerns on the structural example 2 used for the copying machine. FIG. 3 is a schematic diagram when the sensor device is viewed from the charging roller axial direction. 3 is a flowchart showing a flow of exposure condition correction control in the copier.

Next, an embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings.
In the following description, a direct transfer type tandem type image forming apparatus that transfers toner images on four photoconductors onto a recording material carried and conveyed on a recording material conveying member will be described as an example. The present invention is applicable to any image forming apparatus of any system and configuration as long as the image forming apparatus charges the surface of the photoconductor with a charging roller disposed in contact with or close to the surface of the photoconductor. .

FIG. 1 is an explanatory diagram showing a schematic configuration of a copying machine as an image forming apparatus according to the present embodiment.
In the copying machine 1 of the present embodiment, four image forming stations corresponding to yellow, cyan, magenta, and black (black) are arranged in parallel along the belt flat portion of the transfer conveyance belt 9 as a recording material conveyance member. Then, the color toner images formed at the respective image forming stations are sequentially transferred so as to overlap each other on the recording paper as the recording material carried and conveyed on the surface of the transfer conveyance belt 9 to form a full color toner image. Is possible.

  The transfer / conveying belt 9 is hung on two rotatable support rollers disposed to face each other at a required distance in the horizontal direction. This transfer / conveying belt 9 is rotationally driven in the counterclockwise direction in the figure by the driving force from one or both of the support rollers.

Each image forming station includes a photosensitive member 3 and a charging roller 5, an exposure device 4 as an exposure unit, a development device 6 as a development unit, a transfer roller 7 as a transfer unit, and a cleaning unit as a cleaning unit. A device 8 is arranged.
The charging roller 5 has an axial length that is the same as that of the image area on the surface of the photosensitive member, and a charging bias is applied from a power source (not shown).

The exposure device 4 forms an electrostatic latent image on the surface of the photoreceptor 3 uniformly charged by the charging roller 5 by irradiating light based on image information. The exposure apparatus 4 of the present embodiment is composed of a plurality of LED units arranged side by side in the photosensitive member axial direction (charging roller axial direction). The light emission intensity of each LED unit can be individually controlled for each LED unit by a control unit (not shown). The exposure apparatus 4 of the present embodiment is not particularly limited as long as the exposure amount can be individually adjusted in the photosensitive member axial direction (image part region width direction).
The developing device 6 stores a developing sleeve as a developer carrying member configured to be rotatable in a state where a fixed magnet roller is mounted, and a two-component developer obtained by mixing toner and a carrier. And a case for supporting each component such as a sleeve, and arranged so that a required gap is formed between the photosensitive member 3 and the developing sleeve. A developing bias is applied to the developing sleeve from a power source (not shown). The developing device 6 forms a toner image by attaching the toner in the developer carried on the surface of the developing sleeve to the electrostatic latent image formed in the image area on the surface of the photoreceptor 3.
The transfer roller 7 is disposed so as to be in contact with the inner peripheral surface of the transfer conveyance belt 9 that faces the photoreceptor 3 of each image forming station. The transfer roller 7 is formed by forming a conductive foamed polyurethane around the core metal.
The cleaning device 8 is of a blade cleaning type that removes transfer residual toner remaining on the photoreceptor 3 by a cleaning blade, but is not limited thereto.

Next, a series of operations of the copying machine according to the present embodiment configured as described above will be described.
Four color-separated image data (for yellow, cyan, magenta, and black) is generated from the original image read by the scanner 2, and each image forming station forms an image based on the image data of each color. . The transfer / conveying belt 9, the photosensitive member 3, the charging roller 5, the developing sleeve, and the like are driven to rotate at a predetermined timing at which an image can be formed.

First, the description will be given focusing on the image forming station.
First, the charging roller 5 uniformly negatively charges the image area on the surface of the photoreceptor 3. Based on the image data for yellow, the exposure device 4 forms an electrostatic latent image on the surface of the photoconductor, and the developing device 6 performs reverse development with toner having a negative charge, so that the image area of the photoconductor 3 is formed. A yellow toner image is formed. On the other hand, the uppermost recording paper in a state of being stacked on the paper feed tray 83 is sent out by the paper feed roller 82, and is carried on the transfer and transport belt 9 by the transport roller pair 81. The recording paper carried on the transfer conveyance belt 9 is conveyed so as to pass through the transfer section of each image forming station as the surface of the transfer conveyance belt 9 moves. The yellow toner image on the photoreceptor 3 is carried and conveyed on the transfer conveyance belt 9 by a transfer electric field formed between the transfer roller 7 to which a positive bias having a reverse polarity to the toner is applied and the surface of the photoreceptor 3. Transferred onto recording paper. Untransferred toner remaining on the photoreceptor 3 without being transferred by this transfer is removed by the cleaning device 8.

The yellow toner image transferred onto the recording paper on the transfer conveyance belt 9 in this manner moves toward the next image forming station as the transfer conveyance belt 9 moves. In the next image forming station, a cyan toner image is formed on the photoreceptor 3 by the same series of operations as described above. The cyan toner image is transferred onto the recording paper at a predetermined timing overlapping with the yellow toner image on the recording paper carried on the transfer conveyance belt 9. The cyan transfer residual toner that is not transferred by this transfer and remains on the photosensitive member 3 is removed by the cleaning device 8 in the same manner as described above.
In the remaining two image forming stations, similarly to the above, transfer is performed from charging, and magenta and black toner images are transferred onto the recording paper carried on the transfer conveyance belt 9. As a result, a full color toner image is formed on the recording paper. Thereafter, the recording paper on which the full-color toner image is transferred moves toward the fixing device 10 along with the surface movement of the transfer conveyance belt 9, and is pressed and heated by the fixing device 10 so that the full-color toner image is transferred onto the recording paper. A fixed image is formed and discharged onto the discharge tray 85 by the pair of discharge rollers 84.

[Configuration example 1]
Next, a configuration example of the sensor device that constitutes the surface state detection unit that detects the surface state of the charging roller 5 (hereinafter referred to as “configuration example 1”) will be described.
FIG. 2 is a perspective view schematically showing the sensor device of the first configuration example.
FIG. 3 is a schematic diagram of the sensor device of Configuration Example 1 as viewed from the charging roller axial direction.
In the sensor device according to the first configuration example, a sensor 31 as a detection unit is fixed on a timing belt 32 that moves endlessly in parallel with the axial direction of the charging roller 5. The timing belt 32 is stretched and supported by two support pulleys 34, and one support pulley 34 is connected to the drive motor 33. The timing belt 32 moves endlessly by the rotational drive of the drive motor 33, so that the sensor 31 moves along the charging roller axial direction with the surface of the charging roller 5 facing the surface.

The sensor 31 detects the surface state at each position in the axial direction of the charging roller 5.
As a specific example, a configuration in which an optical sensor such as a reflective photosensor is used as the sensor 31 can be given. In this case, the intensity of the reflected light from the surface of the charging roller is detected by the sensor 31 so that the surface state of the charging roller (whether foreign matter is attached to the surface of the charging roller or not is attached to the surface of the charging roller). The amount of foreign matter attached) can be detected.
Another specific example is a configuration using a current sensor capable of detecting a current as the sensor 31. In this case, the current value flowing between the sensor 31 and the surface of the charging roller 5 is detected by bringing the sensor 31 into contact with the surface of the charging roller 5 and applying a specified voltage to the charging roller 5. When a foreign object is present between the sensor 31 and the surface of the charging roller 5, the resistance value increases. Therefore, based on the detection result (current value) of the sensor 31, the surface state of the charging roller (the foreign object adheres to the surface of the charging roller). And the amount of foreign matter adhering to the surface of the charging roller can be detected.

[Configuration example 2]
Next, another configuration example of the sensor device constituting the surface state detection means for detecting the surface state of the charging roller 5 (hereinafter referred to as “configuration example 2”) will be described.
FIG. 4 is a perspective view schematically showing the sensor device of the second configuration example.
FIG. 5 is a schematic view of the sensor device of Configuration Example 2 when viewed from the charging roller axial direction.
In the sensor device of the configuration example 1, the moving means for moving the sensor 31 in the axial direction of the charging roller uses the timing belt 32. However, in the sensor device of the configuration example 2, the spiral screw groove 37a is provided. It differs from the sensor device of the above configuration example 1 in that the guide shaft 37 provided is used. Since the other configuration is the same as that of the sensor device of the first configuration example, only the difference will be described below.

  In the sensor device according to the second configuration example, a guide shaft 37 and a rail 36 extending in parallel with the axial direction of the charging roller 5 are provided. The sensor 31 includes insertion holes through which the guide shaft 37 and the rail 36 are inserted, and the sensor 31 is disposed in a state where the guide shaft 37 and the rail 36 are inserted through the insertion holes. On the inner peripheral surface of the insertion hole through which the guide shaft 37 is inserted, a thread that engages with a spiral thread groove 37 a provided in the guide shaft 37 is formed. With such a configuration, when the guide shaft 37 is rotationally driven by the rotational drive of the drive motor 33, the sensor 31 moves along the guide shaft 37, and the surface of the charging roller 5 faces the charging roller axial direction. Move along.

  In the present embodiment, the surface states at a plurality of locations on the surface of the charging roller having different positions in the image region width direction (charging roller axial direction) are used for the sensor devices of Configuration Example 1 and Configuration Example 2 described above. To detect. Specifically, the rotation of the drive motor 33 is controlled to move the sensor 31 in the charging roller axial direction, and for example, the charging roller surface state is detected by the sensor 31 at regular intervals in the charging roller axial direction. The number and location of the portions detected by the sensor 31 are not particularly limited as long as they are two or more portions having different positions in the charging roller axial direction. The output of the sensor 31 is sent to a control unit (not shown) through a predetermined signal line 35. As will be described later, this control unit performs exposure condition correction control according to the output of the sensor 31.

FIG. 6 is a flowchart showing the flow of exposure condition correction control in the present embodiment.
In this embodiment, the counter counts the number of image formations (number of printed pages) from the initial point in time when the charging roller 5 is unused (when the copying machine is delivered or when the charging roller is replaced) (S1). . When the count value of the counter reaches the specified value (S2), the control unit causes the above-described sensor device to place the charge roller in the axial direction on the surface of the charging roller different from each other whenever a predetermined detection timing arrives. The detecting operation for detecting the surface states at a plurality of locations is performed (S3). The detection results of each part detected by this detection operation are sequentially output from the sensor 31 and input to the control unit. Based on the output value of the sensor 31, the control unit determines whether correction based on the exposure condition is possible (S4). This determination is to determine whether or not the allowable range in which the image density unevenness can be recovered by correcting the exposure condition is exceeded. This allowable range is determined in advance through experiments or the like.

  When it is determined that correction is possible in the above determination, the light emission intensity of the LED unit that exposes a portion corresponding to the position in the charging roller axial direction related to each output value is corrected based on each output value of the sensor 31 ( S5). The larger the amount of foreign matter adhering to the surface of the charging roller 5 (the worse the surface condition), the lower the charging ability at that location, so that the exposed area potential at that location is closer to zero than the normal value. Therefore, the developing potential of the exposed portion is larger than the normal value, and the image density is increased. As a result, image density unevenness occurs in the photosensitive member axial direction (charging roller axial direction). In the present embodiment, the output value of the sensor 31 decreases as the amount of foreign matter adhering to the surface of the charging roller 5 increases. Therefore, the light emission intensity of the LED unit corresponding to the portion where the output value of the sensor 31 is small is reduced. Correct as follows. As a result, it is possible to return the exposure portion potential that has become a value closer to zero than the normal value due to the decrease in charging ability to the normal value. As a result, the developing potential of the exposed portion returns to a normal value, and image density unevenness is reduced.

  In the present embodiment, the case where the correction target is the light emission intensity of each LED unit has been described as an example. However, if the amount of light emitted per unit area can be adjusted, other exposure conditions ( For example, the light emission time of each LED unit) may be a correction target.

  On the other hand, if it is determined in the above determination (S4) that correction is not possible, the charging roller 5 is in an abnormal state, for example, an extraneous foreign matter has adhered to the surface of the charging roller 5, so that the charging roller 5 is replaced. A message such as a message prompting the user is displayed on an operation display panel (not shown) (S6). The user who sees this display calls himself or a service man to perform the work of replacing the charging roller 5. When the replacement operation of the charging roller 5 is completed (S7), the count value of the counter for counting the number of image formations (number of printed pages) is reset (S8).

As described above, in the copying machine according to the present embodiment, the outer peripheral surface of the charging roller 5 is arranged in contact with or close to the entire width of the image area on the surface of the photoreceptor 3 that moves on the surface. By applying a predetermined charging bias to the image area, the image area on the surface of the photosensitive member is charged to a predetermined potential, and the exposed image area is irradiated with light from the exposure device 4 so that the exposed area is irradiated with the light. Image formation in which an image is formed on a recording paper by forming the electrostatic latent image, and then attaching toner to the electrostatic latent image, and finally transferring the resulting toner image onto a recording paper as a recording material Device. The copying machine includes a sensor device as a surface state detection unit that performs a detection operation at a predetermined detection timing to detect a surface state at a plurality of locations on the surface of the charging roller having different positions in the image region width direction, and a sensor device The light emission intensity of each LED unit of the exposure apparatus 4 is adjusted so that the potential difference between a plurality of exposure units having different positions in the image region width direction is reduced based on the detection results of the plurality of locations detected by the sensor 31 And a control unit as a light amount correction unit that corrects the amount of light emitted per unit area of the image region on the surface of the photosensitive member 3. As a result, even if the charging roller surface condition deteriorates and the charging ability unevenness occurs in the charging roller axial direction, the potential of the exposed portion formed on the surface of the photosensitive member differs in the charging roller axial direction (photosensitive member axial direction). The image density unevenness in the direction corresponding to the charging roller axial direction is reduced.
In the present embodiment, as in the configuration example 1 and the configuration example 2 described above, the sensor device is configured so that the sensor 31 that is a detection unit that detects the surface state of the charging roller 5 faces the surface of the charging roller 5. Therefore, the surface condition of these multiple locations can be detected by a smaller number of sensors 31 than the number of multiple locations that are the detection targets.
In particular, as in the sensor device of the configuration example 2 described above, as a moving means for moving the sensor 31 in the charging roller axial direction, the guide shaft 37 provided with a helical screw groove is driven to rotate, thereby rotating the screw groove of the guide shaft 37. Means for moving the sensor 31 engaged with 37 a in the axial direction of the guide shaft 37 is used. With such a moving means, the axial position of the sensor 31 can be finely controlled.
In the present embodiment, as in the configuration example 1 and the configuration example 2 described above, the sensor device is configured so that the sensor 31 that is a detection unit that detects the surface state of the charging roller 5 faces the surface of the charging roller 5. Although the case where the detection operation is performed while moving in the axial direction of the charging roller is described, the configuration in which the sensor 31 is arranged at each of a plurality of detection targets is not excluded.
In the present embodiment, the control unit and the operation display panel cooperate to notify the user that the charging roller 5 should be replaced when the detection result of the sensor device exceeds a predetermined allowable range (No in S4). A notification processing means for performing processing is configured. Thereby, the charging roller can be replaced at an appropriate time, and the original function of the image forming apparatus can be maintained.
In this embodiment, the detection by the sensor device is performed before a predetermined detection unnecessary period (a period until the number of printed pages reaches the specified number of pages) from the initial time point when the charging roller 5 is unused. No operation is performed (S1, S2). During such a detection unnecessary period, it can be estimated that the surface state of the charging roller 5 has not deteriorated yet, so that the detection operation by the sensor device can be omitted. Then, as in this embodiment, by omitting the detection operation by the sensor device during the detection unnecessary period, it is not necessary to perform exposure condition correction control.
Whether or not the sensor device is permitted to perform the detection operation is accepted by an operator display panel as an instruction accepting unit, and whether or not the control unit performs the detection operation by the sensor device according to the content of the instruction. May be determined. In this case, the surface state of the charging roller 5 is detected and the exposure condition is corrected to optimize the image, or the time required for this is reduced without detecting the surface state of the charging roller 5 and the image is recorded. Whether the output time is to be reduced can be appropriately selected by the operator, and convenience is improved.

DESCRIPTION OF SYMBOLS 3 Photoconductor 4 Exposure apparatus 5 Charging roller 6 Developing apparatus 7 Transfer roller 8 Cleaning apparatus 9 Transfer conveyance belt 10 Fixing apparatus 31 Sensor 32 Timing belt 33 Drive motor 34 Support pulley 35 Signal line 36 Rail 37 Guide shaft 37a Screw groove

JP 2002-268296 A

Claims (6)

The outer peripheral surface of the charging roller is placed in contact with or close to the entire width of the image area on the surface of the photosensitive member that moves on the surface, and a predetermined charging bias is applied to the charging roller to apply the predetermined charging bias on the surface of the photosensitive member. The image area is charged to a predetermined potential, and the charged image area is irradiated with light to form an exposed portion irradiated with the light as an electrostatic latent image, and then toner is attached to the electrostatic latent image. In the image forming apparatus for forming an image on the recording material by finally transferring the toner image obtained thereby to the recording material,
A surface state detection means for performing a detection operation for detecting a surface state of a plurality of locations on the surface of the charging roller or the surface of the photoconductor, the positions of which are different from each other in the image region width direction, at a predetermined detection timing;
Based on the detection results for the plurality of locations detected by the surface state detection means, the image area on the surface of the photoreceptor is reduced so that the potential difference between the plurality of exposure sections whose positions in the image area width direction are different from each other. An image forming apparatus comprising: a light amount correcting unit that corrects the amount of light emitted per unit area of the region. The image forming apparatus according to claim 1.
The surface state detection means moves one or more detection portions for detecting the surface state of the charging roller or the photosensitive member in the image portion region width direction so as to face the surface of the charging roller or the photosensitive member. An image forming apparatus that performs the above-described detection operation. The image forming apparatus according to claim 2.
The surface state detection means engages with the screw groove of the guide shaft by rotationally driving a guide shaft provided with a spiral screw groove as a moving means for moving the detection portion in the image region width direction. An image forming apparatus using means for moving the detection unit in the axial direction of the guide shaft. The image forming apparatus according to any one of claims 1 to 3,
An image forming apparatus comprising: a notification processing unit configured to perform a notification process for prompting replacement of the charging roller when a detection result of the surface state detection unit exceeds a predetermined allowable range. The image forming apparatus according to any one of claims 1 to 4, wherein:
The image forming apparatus according to claim 1, wherein the surface state detection unit does not perform the detection operation before a predetermined detection unnecessary period elapses from an initial point in time when the charging roller is unused. The image forming apparatus according to any one of claims 1 to 5,
Having an instruction receiving means for receiving an instruction by an operator as to whether or not the surface state detecting means is allowed to perform a detection operation;
The image forming apparatus according to claim 1, wherein the surface state detection unit determines whether or not to perform the detection operation in accordance with an instruction content received by the instruction reception unit.

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