JP2016020970A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can suppress, at an appropriate timing, an influence in an adjustment mode including adjustment of density and correction of color shift due to a change over time on the surface of an image carrier, so as to contribute to improvement in the accuracy of the adjustment mode, and in turn, improvement of image quality.SOLUTION: Control means, during execution of an adjustment mode such as image density adjustment and color shift correction, adjusts an output value (forward current If) of an optical sensor so that the amount of reflection light (amount of received light) of a texture part of an intermediate transfer belt becomes constant, and acquires an output value after the adjustment (S1); subsequently determines whether or not a ratio between the sensor output value (If) and an initial sensor output value (If0) stored in a memory exceeds a threshold A (1 or more) for executing a belt filming removal mode (S2); and when the ratio exceeds the threshold A, executes the belt filming removal mode (S3). In this case, the control means creates a toner pattern for filming removal on the belt and removes filming with a belt cleaning device.SELECTED DRAWING: Figure 4

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, a plotter, and a multifunction machine provided with at least one of these, and more specifically, a toner image is detected by forming a detection toner image on an image carrier. The present invention relates to an image forming apparatus having an adjustment mode that is detected by a means and performs density adjustment or color misregistration correction based on a detection result.

  In image density adjustment and color misregistration correction control used in an electrophotographic image forming apparatus, the density and position of a detection toner pattern created on a photosensitive drum or an intermediate transfer belt are read and corrected by an optical sensor. ing.

For example, in image density adjustment (process control), light emitted from a light emitting element of a reflective optical sensor is reflected by a background portion of the intermediate transfer belt on which toner is not attached, and the reflected light is received by a light receiving element. The amount of light received according to the reflected light is obtained.
Next, a reference toner image (density adjustment toner pattern) having a predetermined shape is formed on the surface of the photosensitive drum, the reference toner image is transferred onto the intermediate transfer belt, and the light emitted from the light emitting element is emitted. The reflected light is reflected by the reference toner image, and the reflected light is received by the light receiving element to obtain the received light amount according to the reflected light.
Using the amount of received light at the background portion of the surface of the intermediate transfer belt as a reference value, the reference value is compared with the amount of received light in the reference toner image to grasp the toner adhesion amount per unit area of the reference toner image.
Based on the grasped toner adhesion amount, the photosensitive drum charging potential, the developing bias, the optical writing intensity to the photosensitive drum, the control target value of the developer toner density, etc. are adjusted so that the desired toner adhesion amount is obtained. Adjust the image conditions.

In the color misregistration correction, a toner pattern having an angle with respect to the main scanning direction is formed, and a positional deviation between the main scanning direction and the sub scanning direction is detected and corrected.
When density adjustment or color misregistration correction is performed, the output of the optical sensor is adjusted so that a predetermined amount of received light is obtained at the background portion of the intermediate transfer belt surface.
That is, the optical sensor is calibrated so that a predetermined amount of received light can be obtained by adjusting the output (current value) of the light emitting element.

However, if filming occurs in which an additive such as toner or paper accumulates on the intermediate transfer belt as a thin film over time, the glossiness of the belt decreases and the output of the sensor increases.
That is, since the amount of reflected light decreases due to filming, the current value (forward current If) that flows through a light emitting element such as an LED must be increased in order to obtain a predetermined amount of received light.
The current value that flows through the light emitting element is the output value of the sensor.

If the output value of the sensor exceeds the upper limit, density adjustment and color misregistration correction cannot be performed. This is because a sufficient amount of received light cannot be obtained even though the amount of light emission is increased.
Further, there is a problem that the output of the sensor is not stable and cannot be adjusted (corrected) correctly due to uneven filming.
These problems are particularly likely to occur when the image area ratio, the number of output sheets per time are low, or the full color ratio is high.

When the area ratio of the image to be printed is high, the amount of toner input is large, so if filming has occurred on the belt, it will be removed and the belt glossiness will be automatically prevented. It is known that reduced glossiness is raised.
For the purpose of preventing uneven wear of the cleaning blade and preventing defective cleaning, there is also known a control method for forcibly supplying toner to the cleaning blade in accordance with the number of output images (Patent Document 1). reference).
If filming has occurred on the belt due to the supply of toner to the cleaning blade part, this will be removed as a result.

However, since the occurrence of filming depends on how the image forming apparatus is used, even if filming occurs on the intermediate transfer belt over time and the glossiness decreases, a means for removing it at an appropriate timing There was no.
As described above, control for inputting toner for the purpose of improving the cleaning property and preventing blade turning has been conventionally performed, but since the purpose is different and executed regardless of the occurrence of filming, removal of filming is performed. It is not always done at the right time.
For this reason, the problem that the density adjustment and the color misregistration correction cannot be performed due to the temporal change of the surface of the intermediate transfer belt or the like, and the adjustment accuracy and the correction accuracy are still not solved.

  The present invention was devised in view of such a current situation, and it is possible to suppress the influence in the adjustment mode such as the density adjustment and the color misregistration correction due to the change over time of the image carrier surface at an appropriate timing. An object of the present invention is to provide an image forming apparatus that can contribute to improvement in accuracy and, in turn, improvement in image quality.

  In order to achieve the above object, an image forming apparatus of the present invention includes an image carrier that carries a toner image on a surface, and a cleaning that cleans the surface of the image carrier after the toner image is transferred to a transfer target. And a toner image detecting means for detecting a detection toner image formed separately from a normal image forming operation on the image carrier, and a detection result of the detection toner image by the toner image detection means. Adjust the output so that the density of the toner image or color misregistration correction and the amount of light received from the background of the image carrier on which the toner image is not formed or not formed are constant. Compared with the initial output value of the image carrier by the background detection means and the current output value, and when the current output value is higher, the normal image forming operation Is To form a toner image on having a removal mode of removing by said cleaning means.

  According to the present invention, the influence in the adjustment mode such as density adjustment and color misregistration correction due to the time-dependent change of the image carrier surface can be suppressed at an appropriate timing, which can contribute to the improvement of the accuracy of the adjustment mode and consequently the image quality.

1 is a schematic configuration diagram of a color printer as an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a support configuration and a cleaning configuration of an intermediate transfer belt in the color printer. FIG. 4 is a plan view of a principal part showing a density adjustment toner pattern formation position and an optical sensor arrangement position on an intermediate transfer belt. 3 is a flowchart showing a control operation of a control example 1; FIG. 7 is a diagram illustrating a formation position of a toner pattern for filming removal in a belt filming removal mode in a control example 1; 6 is a flowchart showing a control operation of Control Example 2. FIG. 10 is a diagram illustrating a formation position of a toner pattern for filming removal in a belt filming removal mode in a control example 2; 10 is a flowchart showing a control operation of Control Example 3. FIG. 10 is a diagram illustrating a formation position of a toner pattern for filming removal in a belt filming removal mode in a control example 3;

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a color printer as an image forming apparatus according to the present embodiment.
This color printer has a so-called tandem configuration in which four image forming units (process cartridges) having photosensitive drums 2Y, 2C, 2M, and 2K are arranged in the apparatus main body 1, respectively.
Opposite to the photosensitive drum of each image forming unit, an intermediate transfer unit U having an image bearing member composed of an endless belt and an intermediate transfer belt 3 as an intermediate transfer member is disposed.
The intermediate transfer belt 3 is rotatably wound around a plurality of support rollers 4, 5, 6, and 7.
The intermediate transfer belt 3 is rotationally driven in the arrow L direction by driving the support roller 4 as a driving roller in the counterclockwise direction.

The intermediate transfer belt 3 has a multilayer structure, and the base layer is made of, for example, a fluororesin, PVD sheet, or polyimide resin with little elongation, and the surface is covered with a smooth coating layer such as a fluororesin.
Reference numeral 8 denotes a tension roller that presses against the surface of the intermediate transfer belt 3 and applies tension to the intermediate transfer belt 3.
In the present embodiment, the number of photosensitive drums, that is, the number of image forming units is four, but is not limited thereto, and may be five or more.
The number of supporting rollers that support the intermediate transfer belt 3 may be two or more as long as it is necessary for rotationally driving the intermediate transfer belt 3.

The photosensitive drums 2Y, 2C, 2M, and 2K are rotationally driven in the clockwise direction while contacting the surface of the intermediate transfer belt 3, respectively.
The first photosensitive drum 2Y located at the most upstream is charged to a predetermined polarity by the charging roller 9, and the charged surface is irradiated with the light-modulated laser beam emitted from the optical writing unit 10.
As a result, an electrostatic latent image is formed on the first photosensitive drum 2Y, and this electrostatic latent image is visualized as a yellow toner image by the developing device 11.
A transfer voltage is applied to the primary transfer roller 12, whereby the toner image on the photosensitive drum 2Y is primarily transferred onto the surface of the intermediate transfer belt 3 that is rotationally driven in the direction of arrow L.
The transfer residual toner adhering to the photosensitive drum 2Y after the toner image transfer is removed by the cleaning device 13.

In the same manner as described above, a cyan toner image, a magenta toner image, and a black toner image are formed on the second to fourth photosensitive drums 2C, 2M, and 2K, respectively, and each toner image is transferred to the yellow toner image. The toner images are sequentially transferred onto the transfer belt 3 and are transferred onto the intermediate transfer belt 3 so that four color toner images are carried thereon.
A sheet feeding device 14 is disposed in the lower part of the apparatus main body 1. A sheet S as a recording medium and a transfer medium to be transferred from the sheet feeding device 14 is secondary at a predetermined timing by rotation of a pair of registration rollers (not shown). It is conveyed toward the transfer section.
A portion between the portion of the intermediate transfer belt 3 supported by the support roller 4 and the secondary transfer roller 15 disposed to face the portion is a secondary transfer portion.
A transfer voltage is applied to the secondary transfer roller 15, whereby the superimposed toner image on the intermediate transfer belt 3 is secondarily transferred to the paper S.
The secondary transfer roller 15 is pressed against the support roller 4 via the intermediate transfer belt 3 and is driven to rotate counterclockwise while being in contact with the surface of the intermediate transfer belt 3.

The sheet S on which the toner image is transferred is sent to the fixing device 16 where the toner image is fixed on the sheet S by the action of heat and pressure.
The paper S exiting the fixing device 16 is discharged and stacked on a paper discharge tray 17 formed on the upper surface of the apparatus main body 1.
In FIG. 1, reference numeral 18 indicates a toner bottle for supplying toner to the developing device 11.

The toner that could not be transferred remains on the intermediate transfer belt 3 after the secondary transfer.
In order to clean this residual toner, the intermediate transfer unit U is provided with a belt cleaning device 20 as a cleaning means.
As shown in FIG. 2, the belt cleaning device 20 includes a cleaning blade 22 that is in contact with the surface of the intermediate transfer belt 3 and a transport screw 24 that transports the toner scraped off by the cleaning blade 22 to the outside.
A backup roller 26 is disposed on the opposite side of the portion where the cleaning blade 22 contacts the intermediate transfer belt 3.

From the secondary transfer portion, on the downstream side in the rotation direction of the intermediate transfer belt 3, the intermediate transfer belt 3 is opposed to a place where the intermediate transfer belt 3 is wound around the support roller 4 from the front surface side through a predetermined gap. An optical sensor unit 30 is disposed as a toner image detection unit.
As shown in FIG. 3, the optical sensor unit 30 has a configuration in which a plurality of optical sensors (hereinafter also simply referred to as “sensors”) 32 including light emitting elements and light receiving elements are arranged.
That is, a plurality of optical sensors 32 are provided corresponding to each color image forming unit.
Along the belt width direction (main scanning direction) of the intermediate transfer belt 3 so that the detection toner images (density adjustment toner patterns) of the respective colors Y, C, M, and K can be detected in as short a time as possible. Optical sensors 32K, 32M, 32C, and 32Y for each color are provided.
Hereinafter, the intermediate transfer belt 3 is abbreviated as a belt as appropriate.

A light emitting diode (LED) can be used as the light emitting element.
The light emission quantity of the LED can be adjusted by a forward current If flowing through the LED. However, the adjustment parameter of the light emission quantity is not limited to the forward current If, and any adjustment parameter corresponding thereto may be used.
As the light receiving element, a photodiode (PD), a phototransistor (PTr), a photo IC, or the like can be used.
The light emitted from the light emitting element is reflected by the surface of the intermediate transfer belt, and the light receiving element receives the reflected light and outputs a light receiving signal (light receiving amount).
The received light signal is converted into an electrical signal and input to a control means (not shown) as a sensor measurement value.

The color printer according to the present embodiment has an image density adjustment mode, a color misregistration correction mode, and a removal mode.
In the image density adjustment mode (process control), density adjustment toner patterns Kp, Mp, Cp, and Yp as detection toner images are formed and transferred onto the intermediate transfer belt 3 separately from the normal image forming operation.
The toner pattern for density adjustment is detected by each sensor, and the density adjustment as described above is performed based on the detection result.
In the color misregistration correction mode, a color misregistration correction toner pattern as a detection toner image is formed in an inclined state in the main scanning direction separately from the normal image forming operation, and is transferred onto the intermediate transfer belt 3.
The color misregistration correction toner pattern is detected by each sensor, and the positional deviation in the main scanning direction and the sub scanning direction is corrected based on the detection result.
For each sensor, a color misregistration correction toner pattern formed so as to be connected in series in the moving direction of the intermediate transfer belt may be detected.

In the removal mode, the optical sensor unit 30 serves as a background portion detection unit whose output is adjusted so that the amount of light received from the background portion of the intermediate transfer belt 3 is constant.
That is, the optical sensor unit 30 also serves as a background portion detection unit in the removal mode.
The background portion refers to a portion where the toner image is not formed on the surface of the intermediate transfer belt 3 (non-image portion) or a portion where the toner image is not formed in the image forming portion.
The control means compares the initial output value If0 of the background detection means stored in a memory (not shown) with the current output value If, and if the current output value is higher, normal image formation In addition to the operation, control is performed to form a toner image and remove it with the belt cleaning device 20.

The toner image formed in the removal mode is for recovering the surface state of the intermediate transfer belt 3 by removing filming generated on the surface of the intermediate transfer belt 3. The belt is not secondarily transferred but is removed by the belt cleaning device 20.
In this case, the secondary transfer roller 15 is separated.
Since toner is supplied to the cleaning portion by the toner image formed in the removal mode, the coefficient of friction or the scraping function with respect to the surface of the intermediate transfer belt 3 is increased, and filming is removed.

  The initial output value of the background portion detection means means the sensor output value at the background portion of the intermediate transfer belt 3 in the initial stage of use (when new) or the sensor output value at the background portion immediately after filming is removed. .

The removal mode execution timing will be described below.
Hereinafter, the removal mode is referred to as a belt filming removal mode.

[Control Example 1: Implementation between papers]
A control example 1 in the belt filming removal mode will be described with reference to the flowchart of FIG.
The control means adjusts the output value (forward current If) of the optical sensor so that the reflected light amount (light reception amount) of the background portion of the intermediate transfer belt 3 is constant when executing an adjustment mode such as image density adjustment or color misregistration correction. Then, the adjusted output value is acquired (S1).
That is, the sensor output value after adjustment of the amount of reflected light from the background portion that is acquired first when the adjustment mode is executed is acquired as the current sensor output value in the belt filming removal mode. However, the sensor output value acquisition timing is not limited to this.

The ratio between the (current) sensor output value (If) and the initial sensor output value (If0) stored in the memory is an execution threshold A (1 or more) for executing the belt filming removal mode. It is determined whether or not it exceeds (S2).
If the execution threshold A is exceeded, the belt filming removal mode is executed (S3).
In the belt filming removal mode, for normal image formation after execution of the density adjustment and color misregistration correction adjustment modes, the filming removal is performed once every B sheets and between sheets (between recording media = between sheets). The toner pattern is created on the belt, and the belt filming removal mode is executed (S4).
If the execution threshold A is not exceeded in S2, the belt filming removal mode is not executed (S5).

As shown in FIG. 5, the size of the toner pattern Fp formed in the belt filming removal mode is the size w in the width direction orthogonal to the moving direction of the surface of the intermediate transfer belt 3 formed by a normal image forming operation. The maximum size of the sheet S on which the toner image is transferred or the maximum size of the installation width of the optical sensor 32.
In this way, it is possible to remove belt filming in the entire sensor area and the sheet passing width.
In this drawing, an example is shown in which the optical sensor 32 as the background portion detecting means is installed outside the image forming area, but the density adjusting sensor shown in FIG. 3 may be used.
The length t of the toner pattern Fp in the paper conveyance direction is 5 mm or more.
Create a toner pattern for only black in monochrome mode and for each color in full color.

  For example, as shown in Table 1, if a plurality of execution threshold values A and execution number B can be set, toner can be input at an appropriate timing according to the filming state.

As shown in Table 1, when the ratio of the sensor output values is If / If0 <1.5, the belt filming removal mode is not executed.
When the ratio of the sensor output values is 1.5 ≦ If / If0 <2, a toner pattern is created on the belt once between 100 sheets and between sheets.
When the ratio of the sensor output values is 2 ≦ If / If0 <3, a toner pattern is created on the belt once between 50 sheets between sheets.
When the ratio of the sensor output values is 3 ≦ If / If0, a toner pattern is created on the belt once every 10 sheets between papers.

In other words, the worse the filming state, the shorter the execution interval of the belt filming removal mode.
In other words, as the difference between the current sensor output value and the initial sensor output value is larger, the number of executions of the belt filming removal mode is increased.
The area of the toner pattern Fp may be increased as the difference between the current sensor output value and the initial sensor output value increases.

When the belt filming removal mode is executed between sheets, the sheet passing time does not change depending on whether or not the belt filming removal mode is executed.
In a model in which the sheet interval is short and the time for contacting / separating the secondary transfer roller 15 cannot be secured, it is necessary to make the sheet interval longer than usual in the belt filming removal mode.
In this case, when the belt filming removal mode is executed, the sheet passing time becomes longer, and so-called waiting time becomes longer.
Therefore, in a model that adjusts the sheet interval, the waiting time is shorter when the belt filming removal mode is not executed than when it is executed.

The toner pattern Fp may be formed only in an area detectable by the sensor.
The purpose of the filming removal in the present invention is to suppress a decrease in accuracy of sensor calibration due to the filming in the adjustment mode. Therefore, if other areas do not cause a problem, the filming is removed only in the detection area of the sensor. Just do it.
Thus, by setting the formation range of the toner pattern Fp to the minimum necessary range, toner consumption in the belt filming removal mode can be saved.

[Example 2: Implementation at job end]
A control example 2 in the belt filming removal mode will be described with reference to the flowchart of FIG.
Description of the same parts as those in the first embodiment will be omitted as appropriate.
In this control example, the belt filming removal mode is executed at the timing of a job end (at the end of a predetermined number of image forming operations).
It is determined whether or not the acquired sensor output value If is twice or more compared with the initial output value If0 (S2), and if it is twice or more, an execution flag for the belt filming removal mode is set (S3).
The control means counts and accumulates the number of sheets to be passed, and executes the belt filming removal mode at the end of the job after reaching the set number (S4).
That is, as shown in FIG. 7, a toner pattern Fp is created on the belt after transfer to the final sheet.

After executing the belt filming removal mode, the accumulated sheet passing number is reset (S5).
Thereafter, the process is repeated until the next sensor output adjustment is performed.
Double in S2 is an example, and one or more threshold values can be set.

  For example, as shown in Table 2, if a plurality of execution thresholds A and execution sheets C can be set, toner can be input at an appropriate timing according to the filming state.

As shown in Table 2, when the ratio of the sensor output values is If / If0 <1.5, the belt filming removal mode is not executed.
When the ratio of sensor output values is 1.5 ≦ If / If0 <2, a toner pattern is created on the belt for each job end after reaching 100 sheets.
When the ratio of the sensor output values is 2 ≦ If / If0 <3, a toner pattern is created on the belt for each job end after reaching 50 sheets.
When the sensor output value ratio is 3 ≦ If / If0, a toner pattern is created on the belt for each job end after reaching 10 sheets.

When the belt filming removal mode is executed at the job end timing, when the next job is performed after entering the apparatus shutdown operation, the belt job removal mode is entered. Since the belt filming removal mode is performed, the waiting time becomes longer.
Therefore, when the belt filming removal mode is not executed, the waiting time is shorter than when the belt filming removal mode is executed.

[Control Example 3: Implementation in Adjustment Mode]
A control example 3 in the belt filming removal mode will be described with reference to the flowchart of FIG.
Description of the same parts as those in the first embodiment will be omitted as appropriate.
The execution timing of the belt filming removal mode in this control is when the image density adjustment mode is executed or when the color misregistration correction mode is executed.

In the belt filming removal mode in this control, a toner pattern Fp is created on the belt before and after the density adjustment pattern and color misregistration correction pattern in various adjustment modes such as density adjustment and color misregistration correction (S4).
For example, at the time of process control, a toner pattern Fp for belt filming removal mode is created on the belt following the density adjustment pattern.

  For example, as shown in Table 3, when a plurality of execution threshold values A and execution sheet numbers D can be set, the execution interval of the belt filming removal mode is adjusted by shortening the execution interval of the adjustment mode according to the filming state. can do.

As shown in Table 3, when the ratio of the sensor output values is If / If0 <1.5, the belt filming removal mode is not executed.
When the ratio of sensor output values is 1.5 ≦ If / If0 <2, the adjustment mode is entered every 200 sheets, and at the same time, a toner pattern for the belt filming removal mode is created on the belt.
When the ratio of sensor output values is 2 ≦ If / If0 <3, the adjustment mode is entered every 100 sheets, and at the same time, a toner pattern for the belt filming removal mode is created on the belt.
When the sensor output value ratio is 3 ≦ If / If0, the adjustment mode is entered every 50 sheets, and at the same time, a toner pattern for the filming removal mode is created on the belt.

When the belt filming removal mode is executed, since the toner pattern for the filming removal mode is added to the pattern formed in the adjustment mode, the waiting time is increased accordingly.
However, compared to the case where the filming removal mode toner pattern is formed at a timing different from that in the adjustment mode, the user's frustration with respect to the length of the waiting time can be reduced.
In this control, when the belt filming removal mode is not executed, the waiting time is shorter than when the belt filming removal mode is executed.
When the belt filming removal mode is not executed (S5 in FIG. 8), the control unit returns the adjustment mode execution interval to the normal setting.

In the above-described embodiment, the execution target of the filming removal mode is the intermediate transfer belt, but the same can be applied to the photosensitive drum.
In this case, the photosensitive drum is an image carrier and the intermediate transfer belt is a transfer target.
Moreover, in the said embodiment, although the optical sensor unit was set as the structure which also serves as a background part detection means, it is good also as a structure which provides a background part detection means (sensor) separately from an optical sensor unit.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to such specific embodiments, and unless specifically limited by the above description, the present invention described in the claims is not limited. Various modifications and changes are possible within the scope of the gist.
The effects described in the embodiments of the present invention are merely examples of the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

3 Intermediate transfer belt as image carrier 20 Belt cleaning device as cleaning means 30 Optical sensor unit as toner image detection means and background portion detection means

JP 2003-345207 A

Claims (10)

An image carrier that carries a toner image on the surface;
A cleaning means for cleaning the surface of the image carrier after the toner image is transferred to the transfer body;
A toner image detecting means for detecting a detection toner image formed separately from the normal image forming operation on the image carrier;
An adjustment mode for performing density adjustment or color shift correction of the toner image based on the detection result of the detection toner image by the toner image detection means;
A background portion detection means whose output is adjusted so that the amount of light received from the background portion where the toner image of the image carrier is not formed or not formed is constant;
The initial output value of the image carrier by the background detection unit and the current output value are compared. When the current output value is higher, a toner image is formed separately from the normal image forming operation. A removal mode for removal by the cleaning means;
An image forming apparatus. The image forming apparatus according to claim 1.
An image forming apparatus in which the image carrier is an intermediate transfer member, and the toner image detection unit also serves as the background portion detection unit. The image forming apparatus according to claim 1, wherein
An image forming apparatus that increases the number of executions of the removal mode as the difference between the current output value and the initial output value increases. The image forming apparatus according to any one of claims 1 to 3,
An image forming apparatus that increases the area of the toner image formed in the removal mode as the difference between the current output value and the initial output value increases. The image forming apparatus according to any one of claims 1 to 4,
The timing for executing the removal mode is an image forming apparatus at the end of a normal image forming operation. The image forming apparatus according to claim 1, wherein:
The image forming apparatus in which the adjustment mode is an image density adjustment mode for adjusting density, and the timing for executing the removal mode is when the image density adjustment mode is executed. The image forming apparatus according to claim 1, wherein:
The image forming apparatus, wherein the adjustment mode is a color misregistration correction mode for correcting color misregistration, and the timing for executing the removal mode is when the color misregistration correction mode is executed. The image forming apparatus according to any one of claims 1 to 4,
The timing at which the removal mode is executed is an image forming apparatus that is between recording media to which a toner image formed by a normal image forming operation is transferred. The image forming apparatus according to any one of claims 1 to 8,
The size of the toner image formed in the removal mode is such that the width direction orthogonal to the moving direction of the surface of the image carrier is the maximum size of the recording medium to which the toner image formed in the normal image forming operation is transferred. An image forming apparatus that is equal to or larger than a maximum size of an installation width of the background portion detection unit or the toner image detection unit. The image forming apparatus according to any one of claims 1 to 8,
An image forming apparatus in which a toner image formed in the removal mode is formed at a position where the background portion detection unit or the toner image detection unit can detect.

Images