JP2000250366A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device making the toner pattern detecting accuracy improved without giving adverse effects to the service life of pattern holding member such as a photoreceptor drum, a transfer belt and a cleaning blade for cleaning them. SOLUTION: As for this image forming device performing control of the image forming condition in detecting the toner pattern of the AIDC pattern, the resist pattern or the like by an optical sensor 30, etc., in order to extend the service life of the cleaning blades 51, 291 and so on, in the case of performing the press contact and release control of the blade, if abnormal detection value of the toner pattern is detected, the device is made to perform the pattern detection again after cleaning by holding cleaning blades 51 and 291 in press contact with the pattern holding member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a method for forming a toner pattern having a specific shape on the surface of an image carrier such as a photosensitive drum or on a transfer belt, and applying the toner pattern to an optical element. The present invention relates to an image forming apparatus that controls image forming conditions and the like based on a result detected by a detection unit such as a sensor.

[0002]

2. Description of the Related Art In various image forming apparatuses, for example, on the surface of an image carrier such as a photosensitive drum or on a transfer belt,
A toner pattern having a specific shape (hereinafter, simply referred to as a “pattern”) is formed, the formed pattern is detected by a detecting unit such as an optical sensor, and image forming conditions and the like are controlled based on the detection result. ing.

[0003] Such control of image forming conditions and the like (hereinafter referred to as "
This is called “image adjustment”. Examples of the techniques related to (1) include a registration correction operation in a so-called tandem type image forming apparatus, detection of rotation unevenness based on a change in a detection interval of a pattern formed of line segments formed at a predetermined interval on a transfer belt, and rotation Many techniques have been devised, such as correction of unevenness. Hereinafter, as an example of the image adjustment technique, A
Image stabilization control using an IDC (Auto Image Density Control) sensor (hereinafter referred to as “AIDC
Control. " ) Will be described. FIG. 9 shows the AIDC
It is a figure for explaining control.

In FIG. 9, reference numeral 94 denotes a photosensitive drum which is driven to rotate in the direction of arrow X, and 930a denotes an AIDC sensor. The dot area 940a on the surface of the photosensitive drum 94 indicates an area where a toner image of an image to be formed is formed (hereinafter, referred to as an “image forming area”).
A pattern for AIDC control (hereinafter, referred to as an “AIDC pattern”) 940b is formed in a halftone dot region located at a position apart from 40a.

The AIDC pattern 940b is formed by depositing toner on the surface of the photosensitive drum 94 through a process similar to that for a normal image. AID formed
The amount of toner adhering to the surface of the photosensitive drum 94 in the C pattern 940b is detected by the AIDC sensor 930a. Here, as the AIDC sensor 930a, for example, a reflective optical sensor including a light emitting unit and a light receiving unit can be used. That is, for example, a light emitting diode (hereinafter, referred to as
It is described as “LED”. ) Is reflected by the AIDC pattern 940b to detect the amount of light that reaches a light receiving unit using, for example, a photodiode (hereinafter referred to as “PD”). The toner adhesion amount on the surface of the photosensitive drum 94 can be detected.

In the AIDC control, for example, a charging grid voltage or a developing bias in an electrophotographic image forming apparatus, or a T value of a developer in a developing device is determined based on a detection result of a toner adhesion amount by the AIDC sensor 930a.
/ C ratio (the ratio between the amount of toner and the amount of carrier in the two-component developer) and the like, thereby controlling the photosensitive drum 9
A constant amount of adhered toner is obtained on the four surfaces.

In the AIDC control, the density of an actually formed image, specifically, the amount of toner adhering to the surface of the photosensitive drum 94 depends on the installation environment (eg, temperature, humidity, etc.) of the image forming apparatus. Therefore, the operation is always performed to obtain a stable toner adhesion amount. For example, each time an image for one transfer sheet is formed, the AIDC pattern 940b is formed. .

[0008]

The above-mentioned AID
Since the pattern such as the C pattern is frequently formed on the surface of the image carrier such as the photosensitive drum 94 or on the transfer belt, when a certain period of time elapses after the use of the image forming apparatus is started, The image bearing member and the transfer belt (including the case where it is used as an intermediate transfer member; hereinafter, a member on which a pattern is formed is referred to as a “pattern holding member”) due to residual toner or the like become a problem.

Generally, the image forming apparatus has a function of cleaning the residual toner on the pattern holding member by a member such as a blade provided as a cleaning device.
If the blade is always pressed against the surface of the pattern holding member, the pattern holding member and the cleaning blade will be unnecessarily worn, which causes a problem that the life of the members is adversely affected. Therefore, by controlling the pressure contact and separation of the blades, the image forming apparatus is configured to clean only a portion where an image is formed or a pattern is formed, so that a pattern holding member or the like is not unnecessarily worn. Has been put to practical use.

However, in an image forming apparatus which performs the above-described press-contact and separation control in order to shorten the period of press-contact of the blade as much as possible, the surface of the pattern-holding member is not always completely cleaned. There is a problem that a pattern may not be accurately detected by the optical sensor due to dirt. The present invention has been made in view of the above problems,
It is an object of the present invention to provide an image forming apparatus capable of increasing the accuracy of pattern detection without adversely affecting the life of the pattern holding member and the cleaning blade.

[0011]

In order to achieve the above object, an image forming apparatus according to the present invention comprises: a pattern forming means for forming a toner pattern at a predetermined position on a pattern holding member; and detecting a density of the toner pattern. Detecting means for determining whether or not the pattern holding member needs to be cleaned from the output of the detecting means; and determining that the pattern holding member needs to be cleaned by the determining means. And cleaning means for cleaning the pattern holding member when the cleaning is performed.

With this configuration, even when the cleaning blade is not always pressed against the pattern holding member, that is, when the cleaning blade is pressed or separated from the pattern holding member, the detection result obtained by the detecting means is not changed. Since it is possible to determine whether or not the pattern holding member needs to be cleaned, it is possible to clean the pattern holding member as necessary, and therefore, the life of the pattern holding member and the cleaning blade is not adversely affected. , It is possible to increase the accuracy of pattern detection by the detection means.

That is, the pattern forming means forms the toner pattern again after cleaning by the cleaning means, and the detecting means detects and outputs the density of the formed toner pattern again. For example, after the stain on the surface of the pattern holding member is removed, the detection is performed again by the detecting means, so that the influence of the stain on the pattern holding member can be eliminated.

Here, the image forming apparatus further includes display output means for outputting a display to an operator, and display output control means for controlling output to the display output means.
In the case where the state requiring cleaning of the pattern holding member is not resolved even in the detection of the density of the toner pattern again by the detection unit, the determination unit has caused an abnormality in the display output control unit. Receiving the notification from the detection result determining means, and controlling the display output means so as to output to the operator that the apparatus has failed. It is possible to do. The cleaning of the pattern holding member as described above and the subsequent pattern formation and detection are not limited to, for example, performed only once, and may be performed any number of times, but in reality, If the condition in which the stain on the pattern holding member is detected is not resolved in the detection again after the pattern holding member has been once cleaned, the pattern formation is more likely to be caused by the stain on the pattern holding member. Alternatively, it is considered that it is convenient to use that it is determined that there is an abnormality in the pattern detection mechanism and that the fact is output to the user.

Here, the detecting means calculates a difference between a detection result in a portion where the toner pattern is not formed and a detection result in a portion where the toner pattern is formed in the pattern holding member. It may be output as a pattern detection result. As the detection means, specifically, a transmission type or reflection type optical sensor or the like can be used. However, when these optical sensors are used, a portion (background) where a toner pattern is not formed is detected. In many cases, sensor calibration processing is performed so that the result is set to the minimum detection level. That is, by detecting the density of the toner pattern after the calibration processing, the detection result as described above is obtained as a result. The timing at which the sensor calibration process is performed is completely arbitrary. For example, the sensor calibration process may be performed only once after the power is turned on, or may be performed periodically after a predetermined time has elapsed.

In the case where the above-described detecting means is used,
As a case where it is determined that the pattern forming member is dirty, a case where the background portion of the pattern forming member that is detected for the sensor calibration processing is dirty, a case where the pattern forming position is dirty, and the like are considered. . Therefore, the cleaning means, when it is determined by the detection result determination means that the pattern holding member needs to be cleaned,
In the pattern holding member, the detection unit may clean at least one of a portion detected as a portion where the toner pattern is not formed and a portion where the toner pattern is formed. Although it is preferable to extend the life of each member, if the pattern detection accuracy is more important, the cleaning unit determines that the pattern holding member needs to be cleaned by the detection result determination unit. In this case, all the portions of the pattern holding member that can be cleaned by the cleaning unit may be cleaned. The number of times of cleaning is not limited at all, and cleaning may be performed a plurality of times.

Further, the detection result determining means has a life determining section for determining whether or not the life of the pattern forming member is approaching. In addition to the output of the detecting means, the life determining section determines whether the life is short. If it is determined that the pattern holding member is approaching, it may be determined that the pattern holding member needs to be cleaned. Since the pattern holding member becomes particularly dirty when the service life is approaching, if the pattern holding member is not approaching the service life, there is a possibility that an abnormality in the detected value is caused by a trouble of the image adjustment mechanism. Is high, and even if it is determined from the output of the detection means that the pattern holding member needs to be cleaned, the pattern is held only when it is determined that the life of the pattern holding member is approaching. The cleaning of the member is performed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an image forming apparatus according to the present invention will be described with reference to the drawings. (1) Overall Configuration of Image Forming Apparatus FIG. 1 is a schematic sectional view showing the overall configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus shown in FIG. 1 reproduces an image on a recording sheet based on image data input from an external device such as a personal computer or image data obtained by reading a document with an image reading unit (not shown). Is what you do. When image data is input from an external device or the like, the control unit 100
Converts this into a drive signal for a laser diode, and drives a laser diode (not shown) inside the printer head 10 which is a light beam scanning device. The laser beam L emitted from the laser diode is deflected by the folding mirror 2, and then exposes the surface of the photosensitive drum 4 that is driven to rotate in the direction of arrow A in the main scanning direction.

Around the photosensitive drum 4, a drum cleaner 5, an eraser lamp 6, a charging charger 7, a developing unit 8
And a transfer charger 9. Photoconductor drum 4
Before the exposure with the laser beam L, the residual toner is removed by the drum cleaner 5, irradiated with the eraser lamp 6, and then uniformly charged by the charging charger 7. The surface of the charged photosensitive drum 4 has a laser beam L
, An electrostatic latent image is formed, and this electrostatic latent image is visualized as a toner image by the developing device 8.

On the other hand, a recording sheet is fed from a sheet feeding cassette 20 by a pickup roller 21 and a timing roller 22. This recording sheet is a transfer belt 2
By 3, the sheet is conveyed to a transfer position immediately below the photosensitive drum 4. At the transfer position, the toner image formed on the surface of the photosensitive drum 4 is transferred to the recording sheet by the operation of the transfer charger 9. The recording sheet onto which the toner image has been transferred is further conveyed by a transfer belt 23 and a conveyance belt 24, and is discharged to a discharge tray 28 after the toner is fixed by a fixing device 25.

The transfer belt 23 is driven to rotate by a transfer belt drive roller 15 that rotates in the direction of arrow B. A transfer belt cleaner 29 is disposed at a position facing the drive roller 15 with the transfer belt 23 interposed therebetween. . Drum cleaner 5 and transfer belt cleaner 29 of the present embodiment
Have cleaning blades 51 and 291 for cleaning the respective surfaces by pressing against the photosensitive drum 4 or the transfer belt 23, and the respective blades contact the photosensitive drum 4 or the transfer belt 23. It is configured such that it can be pressed and separated. As described above, the pressure contact / separation between the blades 51 and 291 and the photosensitive drum 4 and the transfer belt 23 is performed because the photosensitive drum 4, the transfer belt 23, and the cleaning blades 51 and 291 are used. This is to prevent unnecessary wear and extend the life of each member.

The image forming apparatus according to the present embodiment has
An optical sensor 30a for detecting the toner density of the AIDC pattern attached to the surface of the photosensitive drum 4 is provided.
In the image forming apparatus according to the present embodiment, since the AIDC pattern is formed on the surface of the photosensitive drum 4,
For example, the reflection type optical sensor 30a is arranged at a position facing the surface of the photosensitive drum 4. However, if the AIDC pattern is to be transferred onto the transfer belt 23, the pattern formed on the transfer belt 23 may be used. The optical sensor 30b may be provided at a position where the optical sensor 30b can be detected.

The transfer belt 2 is used as the optical sensor 30b.
3, a transmission type sensor may be used if a transparent material such as polyethylene terephthalate (PET) is used, and a reflection type sensor may be used if a black material having low light transmittance is used. Can also be used. In addition,
In some cases, only one of the optical sensors 30a and 30b may be provided, or both may be provided. For example, A
An IDC pattern is formed on the surface of the photoconductor drum 4, and a toner pattern to be used for another purpose is transferred to the transfer belt 2.
This is because, in the case of forming the image by transferring it onto the substrate 3, it is necessary to provide both. In the present embodiment, a case in which the AIDC control is performed by forming an AIDC pattern on the surface of the photoconductor drum 4 will be described as an example. Hereinafter, the description will be made assuming that only the optical sensor 30a is provided.

The drive control of the optical sensor 30a and the control of the separation / pressing of the cleaning blades 51 and 291 are performed by the control unit 100. The output of the optical sensor 30a is also input to the control unit 100, and the AIDC control is performed. Is performed. The separation and pressure contact of the cleaning blade can be specifically performed using a means such as a solenoid. However, since a known method can be used, detailed description thereof is omitted here.

(2) Configuration of Control Unit 100 Next, the configuration of the control unit 100 in the present embodiment will be described. FIG. 2 shows control unit 10 according to the present embodiment.
FIG. 2 is a functional block diagram showing a configuration of No. 0. As shown in the figure, the control unit of the present embodiment is mainly configured with a CPU 101, which is connected to a ROM 102 storing a program and the like operated by the CPU 101, and a RAM 103 used as a work area of the program. Have been. The RAM 103 according to the present embodiment has
Mode setting area 1031 and cleaning waiting flag area 103
2 is included. The mode setting area 1031 is an area for setting an operation mode.
Reference numeral 032 is an area where a cleaning waiting flag is set. Details of the operation mode and the cleaning waiting flag will be described later.

The control unit 100 includes a transfer charger control unit 104, a charging charger control unit 105, a developing unit control unit 106, a photosensitive drum driving unit 107, a drum cleaner control unit 108, a transfer belt driving unit 109, and a belt cleaner control. It includes a unit 110, and performs AIDC control based on a detection result of a pattern output from the AIDC sensor 30a.

The transfer charger controller 104 applies a transfer voltage in accordance with a predetermined output timing of the transfer charger 9. Here, when applying the transfer voltage, the magnitude of the transfer voltage is controlled based on AIDC control. Further, the charging charger control unit 105 controls a grid voltage for charging the surface of the photoconductor drum 4 based on AIDC control in accordance with charging timing by a predetermined charging charger 7. The developing device controller 106 controls the developing bias voltage based on AIDC control according to a predetermined developing timing. Under the control of these control units, during normal image formation, after a toner image having an appropriate toner density is formed on the surface of the photosensitive drum 4, the toner image is appropriately transferred to a recording sheet. Since these image adjustments are well-known techniques, detailed description thereof is omitted here.

The photosensitive drum driving unit 107 controls the rotation drive of the photosensitive drum 4. This control mainly includes control of the rotation timing for synchronizing with the conveyance of the recording sheet, control of the rotation speed, and the like, and various techniques are being devised. Since there is no direct relationship, a detailed description is omitted here. The drum cleaner control unit 108 controls the photosensitive drum driving unit 10
7 and the like, while controlling the separation and pressure contact of the cleaning blade 51 provided in the drum cleaner 5. In the image forming apparatus according to the present embodiment, as described above,
By controlling the separation and press-contact of the blade 51, only the portion of the surface of the photosensitive drum 4 where the toner image or the pattern is formed is cleaned. Regarding the control of pressing the blade 51 only at the portion where the toner image or the pattern is formed, the control units 104 to 1 of the image forming system
06, in particular, based on the application timing of the developing bias by the developing device control unit 106, the rotation speed of the photosensitive drum 4, and the like. Is omitted.

The transfer belt driving unit 109 controls the rotation of the transfer belt driving roller 15. This control mainly includes control of the rotation timing for synchronizing the conveyance of the recording sheet with the rotation of the photosensitive drum 4, control of the rotation speed, and the like. The belt cleaner control unit 110 controls the separation / pressing of the cleaning blade 291 while cooperating with the transfer belt driving unit 109 and the like. In the image forming apparatus of the present embodiment, by controlling the separation / pressing of the blade 291, only the portion corresponding to the transfer position of the toner image on the surface of the transfer belt 23 is cleaned. The control for pressing the blade 291 only in this portion is mainly performed by the transfer charger control unit 1.
04 and the transfer belt 2
3 can be realized based on the moving speed and the like, but this is also a known technique, and a detailed description thereof will be omitted. In this embodiment, the pattern is not formed on the transfer belt 23. However, when the pattern is formed, it is easy to realize that only the portion corresponding to the pattern forming position is cleaned.

(3) Processing Content of Control Unit 100 Next, the processing content of the control unit 100 in the present embodiment will be described. FIG. 3 is a flowchart showing the processing content of control unit 100 in the present embodiment. As shown in the figure, there are four operation modes of the control unit 100 in the present embodiment: an image forming mode, an image quality adjustment mode, a member cleaning mode, and a trouble mode. Control unit 1
00 repeats the processing based on the operation mode while determining which of the four operation modes to execute (S101). The operation mode is held in the mode setting area 1031 in the RAM 103 as a number indicating the mode, for example, and the operation mode is set as needed by a program executed by the CPU 101.

If the operation mode is the image forming mode, the process proceeds to a normal image forming operation (S102). However, since this is a normal image forming operation, detailed description thereof will be omitted. However, in the image forming operation of the present embodiment, an operation mode is set as needed. That is, after performing image formation for a certain period, the image quality adjustment mode and the member cleaning mode are set to perform image quality adjustment and member cleaning.

If the operation mode is set to the image quality adjustment mode, the process proceeds to the image quality adjustment operation (S103).
Since it is preferable to perform image quality adjustment before performing the first normal image formation, the image quality adjustment mode is set as the first operation mode after the power is turned on in the image forming apparatus of the present embodiment. However, the initial setting is not limited to this. FIG.
5 is a flowchart showing the content of an image quality adjustment operation in the present embodiment.

As shown in the figure, in the image quality adjustment operation, first, the calibration processing of the optical sensor 30a is performed (S20).
1). In the sensor calibration process according to the present embodiment, first, the light emitting unit (LED) of the optical sensor 30a emits light, and the output of the light receiving unit (PD) for the portion (background) where the toner is not adhered on the surface of the photosensitive drum 4 Is calibrated to the 0 level. Further, the output of the light receiving unit when the light emitting unit is turned off is calibrated to the maximum level. That is, in the subsequent pattern detection, the difference between the output of the light receiving portion in the background portion where the toner is not adhered and the output of the light receiving portion in the portion where the toner is adhered is obtained as the detection result.
Note that this sensor calibration process does not need to be performed every time in the image adjustment operation, but may be performed when the power is turned on as described above, or may be performed after a certain time has elapsed. Further, as the output of the light receiving unit, sampling may be performed several times while the light emitting unit is emitting light, and an average value thereof may be obtained.

Next, an image forming system, ie, the printer head 10,
The AIDC pattern is formed on the surface of the photosensitive drum 4 by controlling the charging charger 7, the developing device 8, and the like (S20).
2). More specifically, the surface of the photosensitive drum 4 uniformly charged by the charging charger 7 is exposed by the printer head 10 based on the AIDC pattern image data stored in the ROM 102, and the surface of the photosensitive drum 4 is exposed. After forming an electrostatic latent image of the AIDC pattern on the developing device 8
The AIDC pattern is formed on the surface of the photosensitive drum 4 by toner.

Thereafter, the AIDC by the optical sensor 30a
Wait until the pattern reading timing arrives (S2
03: Yes), the AIDC pattern is read by the optical sensor 30a (S204). Specifically, the AIDC pattern is read by lighting the LED as the light emitting unit and sampling the output value of the PD as the light receiving unit a predetermined number of times (for example, seven times) at a predetermined timing.

Here, a specific shape of the AIDC pattern formed in this embodiment will be described. FIG. 5 is a diagram schematically showing an example of a specific shape of the AIDC pattern formed in the present embodiment. FIG. 2A shows an example in which an AIDC pattern is formed on the surface of the photosensitive drum 4 in the present embodiment, and FIG. 2B shows an example in which an AIDC pattern is formed on the transfer belt 23. It is shown.

As shown in the figure, in the present embodiment, adjustment is made on the charging grid voltage of the charging charger 7, the developing bias voltage of the developing device 8, and the laser gradation of the laser diode included in the print head 10, respectively. To do this, a plurality of gradation patterns P4a to P4e or P23a to P23e are formed for each item.
FIG. 5 shows an example in which a pattern of five gradations is created as a pattern for adjusting the charging grid voltage, for example. Assuming that each key is created, fifteen patterns are formed in total.

The reason why a plurality of patterns are created in this manner is based on the following reasons. That is, for example, a pattern for adjusting the charging grid voltage will be described as an example. By setting the laser gradation and the developing bias to constant values and changing only the charging grid voltage in a gradation manner, a plurality of the above-described plurality is obtained. A pattern can be formed. When the formed pattern is detected by the optical sensor 30a, it is possible to obtain the degree of change in the detection result based on the change in gradation. In the image forming apparatus of the present embodiment, an appropriate charging grid voltage is predicted from the degree of the change. The same applies to the developing bias and the laser gradation. The number of patterns to be formed is not limited to five, and any number of patterns may be formed as necessary, and only one may be formed in some cases.

When the AIDC pattern formed as described above is detected by the optical sensor 30a, the detection result is obtained, for example, in the form of a waveform as shown in FIG. Returning to the flowchart of FIG. 4, the control unit 100 determines whether the pattern read value is abnormal based on the detection result (S20).
5). In the example of FIG. 6, all of the detected values fall within the normal range, and it can be said that the pattern read values are normal. In the present embodiment, for example, as shown in FIG. 7A, when the detected values for all the patterns are below the normal range, or as shown in FIG. If the detected value of the pattern is above the normal range, it is determined that the read value is abnormal.

As a case where such a pattern reading value abnormality is caused by contamination of the pattern forming member, for example, the following situation can be considered. That is, FIG.
Such an output may occur when the portion read as the background in the zero-level calibration of the sensor is dirty.
On the other hand, the output as shown in FIG. 7B may occur when the 0-level calibration is normally performed but the pattern formation position is dirty. Therefore, when these abnormalities occur, cleaning the pattern holding member may contribute to eliminating read value abnormalities.

If it is determined that the read value is not abnormal (S205: No), there is no problem. After performing the normal image quality adjustment processing (S206), the operation mode is performed to perform the normal image formation. Is set to the image forming mode (S
207). Further, at this time, since the cleaning wait flag may be set, the flag is reset (S
208), returning to the flowchart of FIG. Since the cleaning wait flag may not be set in step S208, it is determined whether or not the cleaning wait flag is set before this step, and only when the cleaning wait flag is set, the flag is reset. May be performed. Further, since the image quality adjustment processing is a known processing, detailed description is omitted, but as a result, adjustment of the charging grid voltage, the developing bias, the laser gradation, and the like are performed.

On the other hand, when it is determined that the read value is abnormal (S205: Yes), it is determined whether or not the cleaning waiting flag is set (S209). The cleaning waiting flag is a flag set in the cleaning waiting flag area 1032 in the RAM 103 in the present embodiment. As described later, in this image quality adjustment operation, since the pattern reading value is abnormal, This flag is set when shifting to the member cleaning mode (see S212).
Therefore, the fact that the cleaning waiting flag is set at the point in time after passing through step S209 means that (S209: Ye
s) This means that an abnormality in the pattern reading value has already been detected, and an abnormality in the reading value has been detected in the pattern reading once after the member cleaning operation has been performed.

That is, since the pattern reading value abnormality was not eliminated by cleaning the members, it is determined in this embodiment that a trouble has occurred in the image adjustment mechanism.
The trouble mode is set (S210), the cleaning waiting flag is reset (S208), and the process returns to the flowchart of FIG. Thereafter, in step S105 of the flowchart of FIG. 3, a trouble occurrence is displayed on a display output unit such as a liquid crystal panel (not shown). Detailed explanation of the trouble display is omitted,
The display output means is not limited to the display means capable of displaying characters, figures, etc., such as the liquid crystal panel, but includes lighting and blinking of LEDs and the like, output of sounds such as beeps and electronic sounds, generation of fragrance, It is possible to include all means that can make the user aware of the occurrence of some situation.

If the cleaning waiting flag has not been set in step S209 (S209: No), the member cleaning mode (S211) and the cleaning are performed so that the image adjustment operation is performed again after cleaning the pattern holding member. After setting the wait flag (S212), the process returns to the flowchart of FIG. As described above, the operation mode is the mode setting area 1
Since it is set to 031, the content stored in the area is updated to set the member cleaning mode. The cleaning waiting flag set here indicates that the image quality adjustment operation needs to be performed again after the cleaning of the pattern holding member is completed.

Returning to the flowchart of FIG. 3, when the member cleaning mode is set as the operation mode in step S101, the member cleaning operation (S1) is performed.
04). FIG. 8 is a flowchart showing the detailed contents of the member cleaning operation. As shown in the figure,
In the member cleaning operation, first, the cleaning blade provided in the cleaning device is pressed into contact (S3).
01). In the present embodiment, the pattern is the photosensitive drum 4
Formed on the surface of the drum cleaner control unit 1
By the control of 08, the cleaning blade 51 is pressed against the surface of the photosensitive drum 4. When a pattern is formed on the transfer belt 23, the cleaning blade 291 is pressed against the transfer belt 23 under the control of the belt cleaner control unit 110.

Thereafter, the surface of the photosensitive drum 4 is cleaned by rotating the photosensitive drum 4 for a predetermined time under the control of the photosensitive drum control unit 107. Note that the predetermined time may be a time corresponding to one rotation of the photosensitive drum 4 or may be longer. Also,
When the pattern is transferred onto the transfer belt 23, the cleaning may be performed for a time corresponding to one rotation of the transfer belt, or may be longer.

When the cleaning is completed (S302: Yes),
The cleaning blade 51 is separated (S303), and it is determined whether or not the cleaning waiting flag is set (S3).
04). As described above, when the cleaning wait flag is set (S304: Yes), the image quality adjustment operation needs to be performed again, so that the content of the mode setting area 1031 is updated and the image quality adjustment mode is set ( S305), FIG.
It returns to the flowchart of. If the cleaning waiting flag is not set, it means that the member has been cleaned in the process of performing the normal image forming operation, and the image forming mode is set to return to the normal image forming operation. Are set (S306), and the process returns to the flowchart of FIG.

When an abnormal pattern reading value is detected in the image quality adjustment operation by the above operation, the pattern holding member can be cleaned and the image quality adjustment operation can be performed again. Therefore, even in an image forming apparatus in which the separation and press-contact of the cleaning blade is controlled in order to extend the life of the pattern holding member and the cleaning blade, the influence of the contamination of the pattern holding member is eliminated, and the pattern detection accuracy is improved. It is possible to do.

<Modifications> Although the image forming apparatuses according to the various embodiments of the present invention have been described above, it is needless to say that the contents of the present invention are not limited to the specific examples shown in the above embodiments. Yes, for example, the following modifications can be considered. (1) That is, in the above-described embodiment, the case where the read value abnormality is not detected again in the image adjustment operation (FIG. 4)
Step S209: No), the pattern holding member is always cleaned.
After the determination of 09, it may be further determined whether or not the life of the pattern holding member is approaching, and the pattern holding member may be cleaned only when the life is approaching.

That is, if the life of the pattern holding member is approaching the end of its life, it becomes particularly easy to become dirty. Therefore, only when the life of the pattern holding member is approaching its end, the cleaning is performed and the image adjustment operation is performed again. If not,
It is determined that there is a problem with the image adjustment mechanism, and the mode shifts to the trouble mode. Even in this case, the influence of the stain on the pattern holding member can be eliminated to some extent. The life of the pattern holding member can be determined based on, for example, the number of prints on the recording sheet, the drive time of the photosensitive drum 4 and the transfer belt 23, and the like.

(2) In the above embodiment,
Although a case has been described in which both the drum cleaner 5 and the transfer belt cleaner 29 control the separation and pressure contact of the cleaning blade, the separation and pressure contact may be performed in only one of them. For example, there may be a case where the blade 51 of the drum cleaner 5 is always kept in pressure contact in order to prevent the surface of the photosensitive drum 4 from being damaged. In this case, the strength of the pressing force may be controlled. That is, when an abnormal pattern reading value is detected, the pressure of the cleaning blade 51 can be increased to clean the surface of the photosensitive drum 4.

(3) In the above embodiment, the case where the pattern is formed only on the surface of the photosensitive drum 4 has been described in detail, but as already mentioned in the embodiment,
Even when the pattern is transferred onto the transfer belt 23, application is easy. (4) In the above embodiment, the case where a plurality of patterns are formed as shown in FIG. 5 has been described. However, the number of patterns is not limited at all, and the present invention can be applied to a single pattern. In addition, as described with reference to FIGS. 6 and 7, in the above-described embodiment, when all the detected values are out of the normal range, it is determined that the pattern reading value is abnormal. However, the present invention is not limited to this. In any case, the pattern reading value is determined to be abnormal if it is out of the normal range, or it is determined to be abnormal if it is out of the normal range for a predetermined ratio or more within a predetermined sampling time interval. Various things are possible.

(5) As mentioned in the embodiment, FIG.
In the case where the pattern reading value abnormality described above has occurred, the portion to be cleaned may be estimated from the output value in some cases. That is, if the output as shown in FIG. 7A is obtained, it is conceivable to clean the portion read as the background portion where no toner is attached in the sensor 0 level calibration process. If an output as shown in FIG. 7B is obtained, the portion where the pattern is formed may be cleaned.

These positions can be calculated based on the reading timing of the optical sensor 30a (or 30b), the rotation speed of the photosensitive drum 4, the rotation speed of the transfer belt 23, and the like. ) Or when the detection result as shown in (b) is obtained, it is also possible to control so that only the portion to be cleaned is cleaned. In particular,
An area capable of holding a number is secured as the cleaning waiting flag area 1032, and a reading value abnormality below the normal range as shown in FIG. 7A and a reading value abnormality exceeding the normal range as shown in FIG. Then, the numerical value held as the cleaning waiting flag is changed. Thereafter, when cleaning the pattern holding member in the member cleaning mode, only the necessary portions may be cleaned based on the value set as the cleaning waiting flag.

[0055]

As described above, according to the image forming apparatus of the present invention, the density of the toner pattern formed at a predetermined position of the pattern holding member is detected and output, and the pattern holding It is determined whether or not the member needs to be cleaned, and when it is determined that the member needs to be cleaned, the pattern holding member is cleaned. It is possible to eliminate the influence of dirt on the pattern holding member at the time of detecting a pattern without adversely affecting the life of the pattern, thereby improving the accuracy of pattern detection by detecting means such as an optical sensor. is there.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a functional block diagram illustrating a configuration of a control unit 100 according to the present embodiment.

FIG. 3 is a flowchart showing processing contents of a control unit 100 in the present embodiment.

FIG. 4 is a flowchart illustrating detailed processing contents of an image adjustment operation.

FIG. 5A is a diagram schematically illustrating an example of a pattern formed on the surface of a photoconductor drum 4; FIG. 4B is a diagram schematically illustrating an example of a pattern formed on the transfer belt.

FIG. 6 is a diagram schematically illustrating an example of a result of detecting a pattern with an AIDC sensor.

FIGS. 7A and 7B are diagrams schematically illustrating an example of a detection result indicating that a pattern reading value is abnormal in the present embodiment; FIG.

FIG. 8 is a flowchart showing a detailed processing content of a member cleaning operation.

FIG. 9 is a diagram for describing conventional AIDC control.

[Explanation of symbols]

 Reference Signs List 2 folding mirror 4 photoreceptor drum 5 drum cleaner 51 drum cleaning blade 6 eraser lamp 7 charging charger 8 developing device 9 transfer charger 10 printer head 15 transfer belt drive roller 20 paper feed cassette 21 pickup roller 22 timing roller 23 transfer belt 24 transport belt Reference Signs List 25 fixing device 28 discharge tray 29 transfer belt cleaner 291 belt cleaning blade 30a, 30b optical sensor 100 control unit 101 CPU 102 ROM 103 RAM 1031 mode setting area 1032 cleaning waiting flag area 104 transfer charger control unit 105 charging charger control unit 106 developing device Control unit 107 Photoconductor drum driving unit 108 Drum cleaner control unit 109 Transfer belt driving unit 110 Belt cleaner system Part P4a~P4e pattern P23a~P23e pattern

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Kazuo Okunishi 2-3-1-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Koji Scoop Azuchi-cho, Chuo-ku, Osaka-shi, Osaka 2-3-13, Osaka International Building Minolta Co., Ltd. (72) Inventor Atsushi Kawai 2-3-13-1 Azuchicho, Chuo-ku, Osaka-shi, Osaka Osaka International Building Minolta Co., Ltd. (72) Inventor Yoshiaki Takano Osaka 2-13-13 Azuchicho, Chuo-ku, Osaka-shi Osaka International Building Minolta Co., Ltd. F term (reference) 2H027 DA09 DA10 DE02 EC06 EC10 ED28 GA30 GB07 HB01 HB14 2H032 BA09 BA18 BA30 2H034 BF08 BF12

Claims (7)

[Claims] 1. A pattern forming means for forming a toner pattern at a predetermined position on a pattern holding member; a detecting means for detecting and outputting the density of the toner pattern; and a cleaning of the pattern holding member based on an output of the detecting means. Determining means for determining whether or not the pattern is in a required state; and cleaning means for cleaning the pattern holding member when the determination means determines that the state is in a state requiring cleaning. Image forming apparatus. 2. The method according to claim 1, wherein the pattern forming unit forms the toner pattern again after cleaning by the cleaning unit, and the detecting unit detects and outputs the density of the formed toner pattern again. The image forming apparatus according to claim 1. 3. The image forming apparatus further comprises: a display output unit that outputs a display to an operator; and a display output control unit that controls an output to the display output unit. Even in the detection of the density of the toner pattern again, if the state requiring cleaning of the pattern holding member is not resolved, the display output control unit is notified of the occurrence of an abnormality in the apparatus, and the display output 3. The control unit according to claim 2, wherein the control unit receives the notification from the detection result determination unit, and controls the display output unit so as to output to the operator that an abnormality has occurred in the apparatus. Image forming apparatus. 4. The method according to claim 1, wherein the detecting unit determines a difference between a detection result in a portion where the toner pattern is not formed and a detection result in a portion where the toner pattern is formed in the pattern holding member. The image forming apparatus according to claim 1, wherein the image forming apparatus outputs the detection result. 5. When the cleaning result is determined by the detection result determining means to be in a state where cleaning of the pattern holding member is necessary, the detecting means in the pattern holding member forms the toner pattern. 5. The image forming apparatus according to claim 4, wherein at least one of a portion detected as a portion that has not been cleaned and a portion on which the toner pattern has been formed is cleaned. 6. 6. The cleaning means, when the detection result determination means determines that the pattern holding member needs to be cleaned, all the cleaning means can clean the pattern holding member. The image forming apparatus according to any one of claims 1 to 4, wherein the cleaning of the portion is performed. 7. The detection result determination unit has a life determination unit that determines whether the life of the pattern forming member is approaching. In addition to the output of the detection unit, the life determination unit determines whether the life is short. 7. The image forming apparatus according to claim 1, wherein when it is determined that the pattern holding member is approaching, it is determined that the pattern holding member needs to be cleaned.