Image forming apparatus

Abstract

To reduce an execution time while maintaining the detection accuracy of an image adjustment operation.SOLUTION: A patch pattern is such that a length from a foremost patch (60K0) to a rearmost patch (61YD) included in the patch pattern is longer than a peripheral length Lb that is a length in a conveyance direction Dr of an intermediate transfer belt 12. An engine control unit 203 forms patches (61KL, 61CL, 61ML, 61YL) included in a range (T1 to T2) shorter than the peripheral length Lb of the patches included in the patch pattern at a first density (low density), forms patches (61KD, 61CD, 61MD, 61YD) included in a range (T2 to T3) longer than the peripheral length Lb at a second density (high density) higher than the first density, and performs image adjustment control.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus using an electrophotographic method, and, for example, to image adjustment control. [Background technology]

[0002] Conventionally, image forming apparatuses have an image adjustment function that automatically performs color shift correction and image density adjustment to achieve accurate color reproducibility and color stability. The image adjustment function forms a plurality of measurement images (patches) on a rotating belt, and detects the patches with a sensor provided in the image forming apparatus. The image adjustment function calculates the amount of color shift and density based on the detection timing of the patch and the amount of toner attached, and determines optimal image forming conditions based on the calculation results. Also, as in Patent Document 1, for example, in patch formation control and detection control, the execution time can be reduced by performing image density adjustment together with color shift correction.

[0003] The patch formed on the belt by the image adjustment function is detected by a sensor and then removed from the belt by the cleaning unit. At this time, the cleaning unit was not able to completely remove the patch, and toner remained on the belt. If a patch for the image adjustment function was formed in an area where such a cleaning failure had occurred, there was a risk that the detection accuracy would decrease due to the influence of the remaining toner. For this reason, it is common for the patch for the image adjustment function to be formed within one revolution of the belt. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-106418 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, issues arise in that the patch pattern cannot fit on one revolution of the belt due to the need to increase the number of patches to improve detection accuracy and the shortening of the belt length caused by the miniaturization of the device. In this case, the patch pattern must be divided into multiple parts so that it fits within one revolution of the belt, and the image adjustment function and cleaning must be performed alternately, which creates an issue of longer execution time for the image adjustment function.

[0006] The present invention has been made under these circumstances, and has an object to reduce the execution time while maintaining the detection accuracy of the image adjustment function. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention has the following configuration.

[0008] (1) An image forming apparatus comprising: a forming means for forming an adjustment toner image including a plurality of toner images for adjusting image density; an intermediate transfer body on whose surface the adjustment toner image is formed by the forming means; a detection means for detecting the surface of the intermediate transfer body or the adjustment toner image; and a control means for performing image adjustment control including adjustment of the image density based on the result of detection of the adjustment toner image by the detection means, wherein the length from a leading toner image to a trailing toner image included in the adjustment toner image is longer than a perimeter which is the length in the transport direction of the intermediate transfer body, and the control means forms toner images included in the adjustment toner image within a range shorter than the perimeter at a first density, and forms toner images included in a range longer than the perimeter at a second density denser than the first density, thereby performing the image adjustment control.

[0009] (2) An image forming apparatus comprising: a forming means for forming an adjustment toner image including a plurality of toner images for performing image adjustment; an intermediate transfer body on whose surface the adjustment toner image is formed by the forming means; a first detection means for detecting the surface of the intermediate transfer body or the adjustment toner image; a removal means for removing the adjustment toner image on the intermediate transfer body; and a control means for performing image adjustment control based on the result of detection of the adjustment toner image by the first detection means, wherein the image forming apparatus further comprises a second detection means for detecting whether or not toner remains on the intermediate transfer body after the adjustment toner image has been removed by the removal means, and the length from the leading toner image to the trailing toner image contained in the adjustment toner image is longer than the circumference, which is the length in the transport direction of the intermediate transfer body, and the control means detects whether or not toner remains by the second detection means after the removal means removes toner images contained in the adjustment toner image that are included in a range shorter than the circumference.

[0010] (3) An image forming apparatus including a forming means for forming an adjustment toner image including a plurality of toner images for performing image adjustment, an intermediate transfer body on whose surface the adjustment toner image is formed by the forming means, a detection means for detecting the surface of the intermediate transfer body or the adjustment toner image, a removal means for removing the adjustment toner image on the intermediate transfer body, and a control means for performing image adjustment control based on the result of detection of the adjustment toner image by the detection means, further including a prediction means for predicting whether or not a cleaning defect will occur after the adjustment toner image formed on the intermediate transfer body is removed by the removal means, and the length from the leading toner image to the trailing toner image included in the adjustment toner image is longer than the circumference, which is the length in the transport direction of the intermediate transfer body, and the control means is configured to predict whether or not a cleaning defect will occur after the adjustment toner image formed on the intermediate transfer body is removed by the removal means. an image forming apparatus comprising: an image forming unit that performs a first control in which, when it is predicted that the cleaning defect will occur, a toner image included in the adjustment toner image and included in a range shorter than the circumferential length formed on the intermediate transfer body is removed by the removing unit, and then a toner image included in the adjustment toner image and included in a range longer than the circumferential length is formed by the forming unit; and, when it is predicted that the cleaning defect will not occur by the predicting unit, a toner image included in the adjustment toner image and included in a range shorter than the circumferential length formed on the intermediate transfer body is removed by the removing unit, and then a toner image included in the adjustment toner image and included in a range longer than the circumferential length is formed by the forming unit. Effect of the Invention

[0011] According to the present invention, it is possible to reduce the execution time of an image adjustment operation while maintaining the detection accuracy. [Brief description of the drawings]

[0012] [Figure 1] Schematic diagram of an image forming apparatus according to a first embodiment, and schematic diagram of a reflected light sensor [Diagram 2]Block diagram of an image forming apparatus according to a first embodiment [Diagram 3] FIG. 1 is a flowchart showing color misregistration correction control according to a first embodiment; [Figure 4] FIG. 1 is a flowchart showing image density adjustment control according to the first embodiment; [Diagram 5] FIG. 1 is a diagram for explaining patch formation control in the first embodiment. [Figure 6] Block diagram of an image forming apparatus according to a second embodiment [Figure 7] FIG. 11 is a flowchart showing cleaning failure detection control in the second embodiment; [Figure 8] Flowchart showing retry control in the second embodiment [Figure 9] Block diagram of an image forming apparatus according to a third embodiment [Figure 10] FIG. 13 is a flowchart showing cleaning failure prediction control in the third embodiment, and shows the results of the prediction control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the components described in the embodiment are merely examples, and unless otherwise specified, the scope of the present invention is not limited to these components. EXAMPLES

[0014] (Overview of image forming device) Hereinafter, an image forming apparatus 201 according to a first embodiment to which the present invention can be applied will be described with reference to FIG. 1. FIG. 1(a) shows an outline of the overall configuration of a laser printer engine as a color image forming apparatus. The laser printer engine forms an electrostatic latent image by image light formed based on pixel signals transmitted from a controller unit (not shown), develops the electrostatic latent image, and superimposes and transfers a visible image to form a color visible image. The laser printer engine transfers the color visible image to paper 2 and fixes the color visible image on paper 2. The image forming unit includes photosensitive drums 5 arranged in parallel for each station according to the developing color, a charger 7 as a charging means, a developer 8 as a developing means, a primary transfer roller 4 as a primary transfer means, and an intermediate transfer belt 12 as an intermediate transfer body. For example, the photosensitive drum 5 is more specifically photosensitive drums 5Y, 5M, 5C, and 5K. Here, Y stands for yellow, M for magenta, C for cyan, and K for black, but Y, M, C, and K representing colors are omitted except when describing members related to specific colors.

[0015] The photosensitive drum 5, charger 7, and developing device 8 are mounted in a cartridge 22 that is detachably attached to the main body of the image forming apparatus 201. The photosensitive drum 5 is configured by coating an organic photoconductive layer on the outer periphery of an aluminum cylinder, and is rotated by the driving force of a drive motor (not shown), which rotates the photosensitive drum 5 in a clockwise direction in response to an image forming operation. Exposure light to the photosensitive drum 5 is sent from a scanner unit 10, and an electrostatic latent image is formed by selectively exposing the surface of the photosensitive drum 5 to light. Four chargers 7Y, 7M, 7C, and 7K for charging the photosensitive drums 5Y, 5M, 5C, and 5K are provided with charging rollers 7YR, 7MR, 7CR, and 7KR.

[0016] The image forming apparatus 201 is provided with four developing devices 8Y, 8M, 8C, and 8K for developing yellow (Y), magenta (M), cyan (C), and black (K) at each station in order to visualize the electrostatic latent image. The developing devices 8Y, 8M, 8C, and 8K are provided with developing rollers 8YR, 8MR, 8CR, and 8KR.

[0017] During color image formation, the intermediate transfer belt 12 rotates counterclockwise while in contact with the photosensitive drum 5, and receives the transfer of the visible images in a sequentially superimposed manner by the primary transfer voltage applied to the primary transfer roller 4, forming a color visible image (primary transfer). The intermediate transfer belt 12 transfers the color visible image onto the paper 2 by pinching and conveying the paper 2 at the position of the secondary transfer roller 9 (secondary transfer). Members that contribute to the formation of a color visible image on the intermediate transfer belt 12 (on the intermediate transfer body) are included in the forming means. The primary transfer roller 4 and the secondary transfer roller 9 rotate with the rotation of the intermediate transfer belt 12. The paper 2 is stored in the paper feed tray 1, and is conveyed to the secondary transfer roller 9 by the paper feed roller 40 and the pair of registration rollers 3.

[0018] The fixing section 13 fixes the transferred, unfixed color visible image while transporting the paper 2, and includes a fixing roller 14 for heating the paper 2 and a pressure roller 15 for pressing the paper 2 against the fixing roller 14. The fixing roller 14 and the pressure roller 15 are formed hollow, and a heater is built in the fixing roller 14 and is controlled to maintain an appropriate temperature. The paper 2 holding the color visible image is transported by the fixing roller 14 and the pressure roller 15, and the toner is fixed to the surface by applying heat and pressure. After the visible image is fixed, the paper 2 is discharged to the discharge section 27 by the discharge rollers 31, and the image forming operation is completed.

[0019] Reflected light sensor 50, which is a detection means (first detection means), is disposed facing intermediate transfer belt 12 in image forming apparatus 201 of FIG. 1(a), and can detect the surface of intermediate transfer belt 12 or a patch pattern 60 (see FIG. 1(b)) formed on the surface. In addition, after being used for detection by reflected light sensor 50, the formed patch pattern 60 is collected by cleaning unit 270, and the surface of intermediate transfer belt 12 is maintained in a state free of dirt. Note that each toner image used for image adjustment control is also called a patch, and a patch pattern includes a plurality of patches.

[0020] (Reflected light sensor) FIG. 1B is a diagram illustrating the configuration of the reflected light sensor 50. The reflected light sensor 50 is composed of a light emitting element 51 such as an LED (Light Emitting Diode), a light receiving element 52 such as a photodiode, an IC (not shown) for processing received light data, and a holder (not shown) for accommodating these elements. The light emitting element 51 irradiates light onto the intermediate transfer belt 12, and the light receiving element 52 detects the amount of reflected light by receiving the light reflected from the surface of the intermediate transfer belt 12 or a patch pattern 60 on the intermediate transfer belt 12. The light receiving element 52 includes a light receiving element 52a and a light receiving element 52b. The light receiving element 52a detects the diffuse reflected light and outputs a voltage corresponding to the amount of diffuse reflected light, and the light receiving element 52b detects the regular reflected light and outputs a voltage corresponding to the amount of regular reflected light. By detecting both the regular reflected light and the diffuse reflected light, the density of the patch pattern 60 can be detected from high density to low density. The reflected light sensor 50 outputs the detected specularly reflected light and diffusely reflected light as voltages to an engine control unit 204 (see FIG. 2) described later. Hereinafter, the result of detecting diffusely reflected light is also referred to as the amount of diffusely reflected light, and the result of detecting specularly reflected light is also referred to as the amount of specularly reflected light. The engine control unit 204 functions as a control means for performing image adjustment control, including adjustment of image density, based on the result of detection by the reflected light sensor 50 of an adjustment toner image (a toner image for measurement, a measurement patch) described later.

[0021] (Function block diagram) 2 is a functional block diagram of the first embodiment. The image forming apparatus 201 has a controller unit 202 and an engine unit 203. A toner image (patch) of each color is formed on the intermediate transfer belt 12 by the host computer 200 or the controller unit 202, and image adjustment control is performed. The engine unit 203 has an engine control unit 204, an image forming unit 260, a reflected light sensor 50, and a cleaning unit 270. The engine control unit 204 controls various operations of the engine. The image forming unit 260 controls the laser and high voltage, and actually forms a patch pattern 60 on the intermediate transfer belt 12. The cleaning unit 270 cleans the intermediate transfer belt 12.

[0022] The engine control unit 204 has a color shift correction control unit 210, an image density adjustment control unit 220, and a patch formation control unit 230. As described later, the patch formation control unit 230 performs control to form a patch pattern for image adjustment control. The color shift correction control unit 210 detects a patch for color shift correction used in image adjustment control for correcting color shift of a plurality of colors with a reflected light sensor 50, and acquires the result with a patch data acquisition unit 211 for color shift correction. The patch for color shift correction is formed by the patch formation control unit 230. The color shift calculation unit 212 calculates the amount of color shift with respect to the reference color from the result acquired by the patch data acquisition unit 211. The color shift correction control unit 210 feeds back the result to the image forming unit 260 and reflects it in the image formation timing of each color. Through the above control, the engine control unit 204 adjusts the color shift with respect to the reference color.

[0023] The image density adjustment control unit 220 acquires the result of detection of the patch for image density adjustment formed by the patch formation control unit 230 by the reflected light sensor 50 through the density adjustment patch data acquisition unit 222. The image density adjustment control unit 220 also acquires the result of detection of the surface of the intermediate transfer belt 12 by the reflected light sensor 50 through the background data acquisition unit 221. The density calculation unit 223 calculates the density of the patch from the results acquired by the background data acquisition unit 221 and the patch data acquisition unit 222. The image density adjustment control unit 220 feeds back the result to the image forming unit 260 and reflects it in the process formation conditions. Through the above control, the engine control unit 204 adjusts the maximum density and halftone gradation characteristics of each color.

[0024] (Color shift correction control unit) Next, the flow of color misregistration correction control executed by the color misregistration correction control unit 210 in the first embodiment will be described with reference to the flowchart in Fig. 3(a). In step (hereinafter, abbreviated as S) 301, the color misregistration correction control unit 210 causes the patch formation control unit 230 to form patch patterns 60K, 60C, 60M, and 60Y for color misregistration correction shown in Fig. 3(b) on the intermediate transfer belt 12.

[0025] (Patch for color misregistration correction) 3(b) is a diagram showing a patch pattern 60 for color misregistration correction formed on the intermediate transfer belt 12 by the patch formation control unit 230. In detail, the patch pattern 60 for color misregistration correction has a yellow patch 60Y, a magenta patch 60M, a cyan patch 60C, and a black patch 60K. Note that the patches 60Y to 60K are formed in the order of Y, M, C, and K from upstream to downstream with respect to the conveyance direction Dr of the intermediate transfer belt 12. Therefore, the reflected light sensor 50 detects the patch pattern 60 in the order of patch 60K, patch 60C, patch 60M, and patch 60Y.

[0026] Furthermore, the patch pattern 60 is formed at a position (position in a direction perpendicular to the transport direction Dr) that can be detected by the reflected light sensor 50. Furthermore, T1 is a reference position on the intermediate transfer belt 12, which is a rotating body, and T2 is a position Lb that is one revolution from T1, that is, the length (hereinafter also referred to as the circumference) of the intermediate transfer belt 12. T1 is also expressed as x=0, and T2 is also expressed as x=Lb. Since the intermediate transfer belt 12 is an endless rotating body, in reality, T1=T2.

[0027] Returning to the explanation of FIG. 3(a), in S302, the color shift correction control unit 210 acquires patch data by the patch data acquisition unit 211 for color shift correction. The patch data is data acquired by reading the output (e.g., voltage) of the reflected light sensor 50. In FIG. 3(b), the black patch 60K that arrives first at the reflected light sensor 50 is set as a reference color patch (hereinafter referred to as a reference color patch), and timing data is acquired until the other color patches 60C, 60M, and 60Y arrive. The timing data is obtained by measuring the timing at which each of the patches 60C, 60M, and 60Y is detected using a timer (not shown) included in the engine control unit 204 with the timing at which the patch 60K is detected as a reference.

[0028] In S303, color shift correction control unit 210 calculates the amount of color shift of each color relative to K, which is the reference color, by color shift calculation unit 212, based on the timing data of the patch for adjusting color shift acquired by patch data acquisition unit 211 in S302. Note that color shift calculation unit 212 stores information indicating the relationship between timing data and the amount of color shift, such as a table or a relational expression, in a storage unit (not shown) in advance, and calculates the amount of color shift based on this. In S304, color shift correction control unit 210 feeds back to the image formation timing when image forming unit 260 operates.

[0029] (Image density adjustment control unit) Next, the flow of image density adjustment control executed by the image density adjustment control unit 220 of the first embodiment will be described with reference to the flowchart of FIG. 4(a). In S401, the image density adjustment control unit 220 acquires background data 61K0, 61C0, 61M0, and 61Y0 in a state where nothing is drawn on the intermediate transfer belt 12 as shown in T1 to T2 of FIG. 4(b) by reading the output of the reflected light sensor 50 through the background data acquisition unit 221. In S402, the image density adjustment control unit 220 forms patches 61K1, 61C1, 61M1, and 61Y1 for image density adjustment shown in T2 to T3 of FIG. 4(b) on the intermediate transfer belt 12 through the patch formation control unit 230. If T1 to T2 is the first rotation of the intermediate transfer belt 12, T2 to T3 is the second rotation of the intermediate transfer belt 12 (T3 x=2Lb). In S403, the image density adjustment control unit 220 acquires patch data by reading the output of the reflected light sensor 50 using the patch data acquisition unit 222 for density adjustment.

[0030] (Patch for density adjustment) FIG. 4B is a diagram showing a patch pattern 61 for density adjustment formed on the intermediate transfer belt 12 by the patch formation control unit 230. The patch pattern 61 for density adjustment is a plurality of toner images for adjusting image density. Specifically, the patch pattern 61 for density adjustment has a yellow patch 61Y, a magenta patch 61M, a cyan patch 61C, and a black patch 61K. Note that the patches 61Y to 61K are formed in the order of Y, M, C, and K from upstream to downstream within a range from T2 to T3 with respect to the conveyance direction Dr of the intermediate transfer belt 12. Therefore, the reflected light sensor 50 detects the patch pattern 61 in the order of patch 61K, patch 61C, patch 61M, and patch 61Y.

[0031] Furthermore, the patch pattern 61 is formed at a position (position in a direction perpendicular to the transport direction Dr) that can be detected by the reflected light sensor 50. T3 represents a position at a circumference Lb from T2, and in reality, the background data 61K0, 61C0, 61M0, and 61Y0 are detected during the first rotation of the intermediate transfer belt 12, and the patches 61K1, 61C1, 61M1, and 61Y1 are formed during the second rotation.

[0032] Returning to the explanation of Fig. 4(a), in S404, the image density adjustment control unit 220 calculates each color patch density from the background data acquired by the background data acquisition unit 221 in S401 and the patch data for density adjustment acquired by the patch data acquisition unit 222 in S403. For example, taking Y as an example, the following formula 1 is used to calculate the patch density. (Formula 1) Y patch data = specular reflection amount of patch 61Y1 - diffuse reflection amount of patch 61Y1 × α Y substrate data = specular reflection amount of substrate data 61Y0 - Diffuse reflection light amount of 61Y0 x α Y patch density = Y patch data ÷ Y background data

[0033] In formula 1, α is the minimum value of the output ratio between regular reflection light and diffuse reflection light calculated from the maximum density patch of each color. From the result of calculating the patch density using formula 1, the image density adjustment control unit 220 feeds back to the process formation conditions in S405.

[0034] (Patch formation control unit) The patch formation control unit 230 performs control to form patch patterns 60, 61 used by the above-mentioned color misregistration correction control unit 210 and image density adjustment control unit 220. The patch formation control unit 230 transmits a toner image of the patch pattern to be formed as a laser control signal to the image forming unit 260. Note that a signal transmitted from the controller unit 202 may be used as the laser control signal for outputting the patch pattern.

[0035] FIG. 5(a) is a diagram showing an example of patch patterns that are toner images for adjusting images formed on the intermediate transfer belt 12. The patch patterns are composed of patch patterns 60 for color shift correction and patch patterns 61 for image density adjustment output from each station, and the patches are spaced apart so as not to overlap each other. More specifically, the patch patterns 60 for color shift correction, which are the second toner image group, have 60K0, 60C0, 60M0, 60Y0, 60K1, 60C1, 60M1, and 60Y1. The patch patterns 61 for image density adjustment, which are the first toner image group, have 61KL, 61CL, 61ML, 61YL, 61KD, 61CD, 61MD, and 61YD. The number and types of patch patterns are not limited to those shown in this example, and may vary depending on the time required for color shift and density control, the required accuracy, and the like.

[0036] The patch patterns 60 for correcting color misregistration are arranged at predetermined intervals so as to cancel the amount of color misregistration due to the rotational cycle of rotating bodies such as the intermediate transfer belt 12 and the photosensitive drum 5. For this reason, the intervals between the two patch groups (60K0, 60C0, 60M0, 60Y0) for correcting color misregistration and the patch group (60K1, 60C1, 60M1, 60Y1) are used to form the patch pattern 61 for adjusting image density. This makes it possible to reduce the execution time of the image adjustment function.

[0037] 5(a), in order to improve the accuracy of image density adjustment, patch patterns 61 for adjusting the density of each of the low-density region and the high-density region are arranged. That is, the patch formation control unit 230 forms low-density patches 61KL, 61CL, 61ML, and 61YL, which are the first density for adjusting the density of the low-density region. The patch formation control unit 230 also forms high-density patches 61KD, 61CD, 61MD, and 61YD, which are the second density darker than the first density for adjusting the density of the high-density region. As a result of this, as shown in FIG. 5(a), the patch patterns have a length of more than one revolution of the intermediate transfer belt 12.

[0038] 5A, the length from the first toner image (patch 60K0) to the last toner image (patch 61YD) included in the patch pattern is longer than the circumferential length, which is the length in the transport direction Dr of the intermediate transfer belt 12. That is, if the length of the patch pattern is the pattern length Lp and the circumferential length in the transport direction Dr (which is also the rotation direction) of the intermediate transfer belt 12 is the circumferential length Lb, then the relationship Lp>Lb holds. Note that in the patch pattern of FIG. 5A, patches 60K0 to 61Y1 are formed from T1 to T2 (the first rotation of the intermediate transfer belt 12), and patches 61KD to 61YD are formed from T2 to T3 (the second rotation of the intermediate transfer belt 12).

[0039] However, as described above, a patch pattern that spans more than one revolution of the intermediate transfer belt 12 may reduce detection accuracy due to poor cleaning. In normal printing, the cleaning unit 270 can remove a small amount of toner (hereinafter referred to as residual toner) that has not been transferred to the paper 2 for each revolution of the intermediate transfer belt 12. However, with the image adjustment function, more toner than the residual toner reaches the cleaning unit 270 at one time, so there is a risk that the cleaning unit 270 will not be able to remove the toner.

[0040] 5A, that is, if the cleaning unit 270 cannot remove the toner of the patch drawn on the first rotation of the intermediate transfer belt 12, the toner will remain as dirt on the second rotation of the intermediate transfer belt 12 in the range from T2 to T3. This may affect the detection accuracy when the reflected light sensor 50 detects the patch formed in the range from T2 to T3.

[0041] In order to reduce the effect of this dirt on the detection accuracy in the second rotation, the patch formation control unit 230 in the first embodiment forms a patch for adjusting the density of the low density region (hereinafter referred to as a low density patch) in the first rotation of the intermediate transfer belt 12 from T1 to T2, and forms a patch for adjusting the density of the high density region (hereinafter referred to as a high density patch) in the second rotation of the intermediate transfer belt 12 from T2 to T3. That is, the patches 61KL, 61CL, 61ML, and 61YL in FIG. 5(a) are low density patches, and the patches 61KD, 61CD, 61MD, and 61YD are high density patches.

[0042] This is because high-density patches are less susceptible to contamination by remaining toner than low-density patches. Thus, in the first embodiment, the average density of density adjustment patches included from the head to the perimeter Lb in the patch pattern is higher than the average density of density adjustment patches included from the head to the perimeter Lb. Note that, since the patch pattern 61 includes multiple patches, the densities of the multiple patches are averaged. Also, in order to prevent the density adjustment patches formed from T2 to T3 from being affected by the remaining toner, the patches may be made to have a higher density than the densest remaining toner, for example.

[0043] (effect of poor cleaning) The fact that high-density patches are less affected when a cleaning failure occurs compared to low-density patches will be explained using the experimental data shown in Figures 5(b) and 5(c). Figure 5(b) shows the measurement results (voltage) when there is a cleaning failure and when there is no cleaning failure, and Figure 5(c) shows the calculation results of Equation 1 based on the measurement results in Figure 5(b).

[0044] As shown in FIG. 5(c), in the case of the minimum density patch, the difference between when no cleaning failure occurs and when a cleaning failure occurs is 0.3. In the case of the maximum density patch, the difference between when no cleaning failure occurs and when a cleaning failure occurs is 0.01, which is smaller than the difference in the case of the minimum density patch. As described above, although there is an increase in density due to the influence of the remaining toner in both the minimum density patch and the maximum density patch, the influence of the high density patch is small compared to the influence of the low density patch, and conversely, it can be seen that the influence of the low density patch is large. From the difference between when there is a cleaning failure and when there is no cleaning failure in FIG. 5(c), the minimum density patch is more greatly influenced by the remaining toner than the maximum density patch. Therefore, as in the first embodiment, by forming a low density patch in the first rotation and a high density patch in the second rotation, even if the patch pattern extends over one or more rotations of the intermediate transfer belt 12, the detection accuracy is prevented from decreasing when a cleaning failure occurs.

[0045] In this way, the engine control unit 204 forms patches included in the patch pattern that are included in a range shorter than the circumferential length Lb of the intermediate transfer belt 12 in a first density, and forms patches included in a range longer than the circumferential length Lb in a second density darker than the first density. The range shorter than the circumferential length Lb corresponds to the range from T1 to T2 in FIG. 5A, and the patches included in that range correspond to the patches 61KL, 61CL, 61ML, and 61YL. The range longer than the circumferential length Lb is the range of the next revolution of the intermediate transfer belt 12, which corresponds to the range from T2 to T3 in FIG. 5A, and the patches included in that range correspond to the patches 61KD, 61CD, 61MD, and 61YD.

[0046] As described above, according to the first embodiment, when a patch pattern is formed for one or more revolutions of the belt in the image adjustment function, a low density patch is formed in the first revolution and a high density patch is formed in the second revolution. As a result, the high density patch in the second revolution is hardly affected by poor cleaning, and it is possible to shorten the time required for cleaning before forming the patch in the second revolution, which was previously required.

[0047] As described above, according to the first embodiment, it is possible to reduce the execution time of the image adjustment operation while maintaining the detection accuracy. EXAMPLES

[0048] The second embodiment has the same configuration as the image forming apparatus 201 in Fig. 1, and is characterized in that it includes a cleaning detection means for detecting whether the cleaning unit 270 has removed toner, and changes the processing of the image adjustment function according to the cleaning detection result. The cleaning unit 270 functions as a removal means for removing the patch pattern on the intermediate transfer belt 12. Explanations of the same points as in the first embodiment will be omitted.

[0049] (Function block diagram) FIG. 6 is a functional block diagram of the second embodiment. The cleaning failure detection control unit 240 detects the occurrence of a cleaning failure using the reflected light sensor 50. The detection control unit 240 functions as a second detection unit that detects whether or not toner remains on the intermediate transfer belt 12 after the patch pattern is removed by the cleaning unit 270. In addition, the engine control unit 204 changes the control of the image adjustment function according to the detection result of the detection control unit 240. When a retry is determined based on the detection result of the cleaning failure detection control unit 240, the retry control unit 250 cleans the intermediate transfer belt 12 and then retries the image adjustment function. In other words, the retry control unit 250 can be said to be an image adjustment retry unit that performs image adjustment again when the detection control unit 240 detects an insufficient cleaning state. The functions other than those described above are the same as those of the first embodiment, so their explanations will be omitted.

[0050] (Cleaning failure detection control unit) 7A, a description will be given of the cleaning defect detection control executed by the cleaning defect detection control unit 240. Note that the cleaning defect detection control operates during the image adjustment control, and the patch pattern for the image adjustment control is drawn on the intermediate transfer belt 12 by the patch formation control unit 230.

[0051] In S701, the detection control unit 240 acquires background data of the intermediate transfer belt 12 using the reflected light sensor 50. The background data acquired here is background data at the same positions as the patches K2 and C2 formed on the intermediate transfer belt 12 from T2 to T3, such as K1 and C1 shown in FIG. 7B. In S702, the detection control unit 240 acquires cleaning data K3 and C3, which are background data one revolution after the formation of the patches K2 and C2, using the reflected light sensor 50. The cleaning data K3 and C3 are data of the surface of the intermediate transfer belt 12 on which no patch is formed, after cleaning the patches K2 and C2. The cleaning data K3 and C3 are data of the same positions as the patches K2 and C2 formed on the intermediate transfer belt 12, as in S701.

[0052] In S703, the detection control unit 240 detects a cleaning defect using the base data obtained in S701 and the cleaning data obtained in S702. Specifically, the detection control unit 240 compares the base data K1 and cleaning data K3 in Fig. 7(b) and also compares the base data C1 and cleaning data C3. Taking C as an example, the comparison is performed using the following formula 2. (Formula 2) C1×β>C3

[0053] The detection control unit 240 detects a cleaning defect when formula 2 is satisfied. In formula 2, C1 is the base data, C3 is the cleaning data, and β is a coefficient used for detecting a cleaning defect. In the second embodiment, the coefficient β is set to 0.98. For example, when the base data C1 is 2.1 V, if the cleaning data C3 is less than 2.058 V, the detection control unit 240 determines that a cleaning defect has occurred. When toner is on the surface of the intermediate transfer belt 12 due to a cleaning defect, as in the cleaning data C3 of FIG. 7(b), a large difference occurs from the base data C1, and therefore the detection control unit 240 determines that a cleaning defect has occurred.

[0054] In S704, the detection control unit 240 determines whether or not there is a cleaning defect based on the cleaning defect detection in S703. If the detection control unit 240 determines in S704 that there is no cleaning defect, the process ends. If the detection control unit 240 determines in S704 that there is a cleaning defect, the process proceeds to S705. In S705, the detection control unit 240 performs retry control using the retry control unit 250.

[0055] In this way, while performing image adjustment control, engine control unit 204 removes toner images included in an area shorter than circumferential length Lb from among the patches included in the patch pattern by cleaning unit 270. After that, engine control unit 204 detects whether the patch pattern has been removed by detection control unit 240. In other words, detection control unit 240 determines the cleaning status after the patch pattern has passed through cleaning unit 270 by a distance equal to or greater than circumferential length Lb during image adjustment execution (after T3 in FIG. 7B).

[0056] (Retry control unit) The retry control performed in S705 of Fig. 7 when a cleaning defect is detected by the cleaning defect detection control unit 240 will be described with reference to the flowchart of Fig. 8. In S801, the retry control unit 250 holds the patch data of the first round in the range from T1 to T2 in Fig. 5, which is not affected by the cleaning defect, among the patch data acquired by the density adjustment patch data acquisition unit 222. Note that the data from the second round onwards in the range from T2 to T3 in Fig. 5 is not used because it is affected by the cleaning defect.

[0057] In S802, the retry control unit 250 controls cleaning of the intermediate transfer belt 12. That is, cleaning is performed again at this timing. In S803, the retry control unit 250 causes the patch formation control unit 230 to form only the patch pattern for the second rotation, which is in the range from T2 to T3 in FIG. 5, on the intermediate transfer belt 12. In S804, the retry control unit 250 causes the patch data acquisition unit 222 for density adjustment to acquire the patch data for the second rotation formed in S803.

[0058] By performing image adjustment by combining the first round data acquired in S801 and the second round data acquired in S804, it is possible to maintain the accuracy of image adjustment even during retry control. Note that when the cleaning defect detection control unit 240 detects a cleaning defect, it is not necessary to perform retry control, and image adjustment control may be performed using only the patch data from the first round.

[0059] In this way, when the detection control unit 240 detects that toner remains on the intermediate transfer belt 12, the engine control unit 204 removes the toner remaining on the intermediate transfer belt 12 by the cleaning unit 270. After that, the engine control unit 204 forms a toner image included in a range longer than the circumference Lb of the patch pattern. The engine control unit 204 performs adjustment control based on two results. One of the two results is a detection result of the reflected light sensor 50 detecting a patch included in a range shorter than the circumference Lb before removal by the cleaning unit 270. The other of the two results is a result of the reflected light sensor 50 detecting a patch included in a range longer than the circumference Lb formed after the cleaning unit 270 removes the toner remaining on the intermediate transfer belt 12. That is, the retry control unit 250 does not form at least a patch within a range of Lp (pattern length) - Lb (circumference) from the beginning of the pattern among the patches within the circumference Lb from the beginning of the pattern when forming the patch pattern. The retry control unit 250 performs image adjustment using both the detection result of the range from the head of the pattern to the circumference Lb detected in the immediately previous image adjustment and the detection result at the time of the retry. The engine control unit 204 may perform adjustment control based only on the detection result of the reflected light sensor 50 detecting a patch included in a range shorter than the circumference Lb before removal by the cleaning unit 270. That is, when an insufficient cleaning state is detected, the engine control unit 204 may perform image adjustment using only the detection result of the patch detected by the reflected light sensor 50 in the range from the head of the pattern to the circumference Lb.

[0060] As described above, according to the second embodiment, if a cleaning failure is detected when a patch pattern is formed for one or more revolutions of the belt in the image adjustment function, correct patch data can be obtained after the occurrence of the cleaning failure by retry control. Therefore, it is possible to maintain the detection accuracy of the image adjustment function. Also, if the cleaning performance of the intermediate transfer belt 12 is sufficient, the execution time can be shortened by ending the control after one image adjustment.

[0061] As described above, according to the second embodiment, it is possible to reduce the execution time of the image adjustment operation while maintaining the detection accuracy. EXAMPLES

[0062] The third embodiment has the same configuration as the image forming apparatus 201 in Fig. 1, and is characterized in that cleaning defects are predicted using an environment sensor 70 that measures the environment (not shown in Fig. 1) and the like, and the processing of the image adjustment function is changed according to the prediction result. Explanations of the same parts as in the first and second embodiments will be omitted.

[0063] (Function block diagram) FIG. 9 is a functional block diagram of the third embodiment. A cleaning failure prediction control unit 280 predicts a cleaning failure using life data of the intermediate transfer belt 12 and the cleaning unit 270 and the detection result of the environmental sensor 70. The environmental sensor 70 functions as a temperature detection means for detecting the environmental temperature. The prediction control unit 280 functions as a prediction means for predicting whether or not a cleaning failure will occur after the patch pattern formed on the intermediate transfer belt 12 is removed by the cleaning unit 270. In addition, the engine control unit 204 changes the control of the image adjustment function according to the prediction result. Functions other than those described above are similar to those of the first and second embodiments, so a description thereof will be omitted.

[0064] (Cleaning failure prediction control) The cleaning failure prediction control executed by the cleaning failure prediction control unit 280 will be described with reference to the flowchart of FIG. 10(a). In S1001, the prediction control unit 280 predicts a cleaning failure using remaining life data of the intermediate transfer belt 12 calculated from the use times of the intermediate transfer belt 12 and the cleaning unit 270, and the environmental temperature acquired by the environmental sensor 70. The use times of the intermediate transfer belt 12 and the cleaning unit 270 are assumed to be accumulated in a storage unit of the engine control unit 204. In addition, the storage unit is assumed to store in advance, for example, a table showing the relationship between the use time and the remaining life of the intermediate transfer belt 12, a relational expression showing the relationship between the use time and the remaining life of the intermediate transfer belt 12, or the like. The engine control unit 204 functions as a life acquisition unit that acquires the remaining life of the intermediate transfer belt 12 based on the use time and the table or the relational expression. The prediction control unit 280 predicts whether or not the patch pattern formed on the intermediate transfer belt 12 will be removed by the cleaning unit 270 based on the detection result of the environmental sensor 70 and / or the remaining life (acquired result) of the intermediate transfer belt 12.

[0065] FIG. 10B shows the judgment conditions and results of cleaning failure prediction in the third embodiment. The judgment conditions are the environmental temperature acquired by the environmental sensor 70 and the remaining life (belt life) of the intermediate transfer belt 12, and the cleaning failure is predicted according to the respective thresholds, and the operation of the image adjustment control is changed. For example, when the environmental temperature detected by the environmental sensor 70 is 5° C. or higher and the belt life is 30% or less, the prediction control unit 280 predicts that a cleaning failure will not occur (NO). For example, even if the environmental temperature detected by the environmental sensor 70 is 5° C. or higher, when the belt life is 0%, the prediction control unit 280 predicts that a cleaning failure will occur (YES). Furthermore, when the environmental temperature detected by the environmental sensor 70 is less than 5° C., the prediction control unit 280 predicts that a cleaning failure will occur (YES) regardless of the belt life. The cleaning failure prediction control unit 280 may make a judgment using the result detected by the cleaning failure detection control unit 240 described in the second embodiment when the image adjustment control was executed the previous time. 10B, the predictive control unit 280 makes a prediction based on the environmental temperature and the belt life, but the prediction may also be made by adding the life of the cleaning unit 270 to the judgment conditions. Furthermore, the predictive control unit 280 may make a prediction using at least one of the environmental temperature, the belt life, and the life of the cleaning unit 270.

[0066] In S1002, the predictive control unit 280 predicts whether or not there is a high possibility of a cleaning failure occurring based on the cleaning failure prediction in S1001. If the predictive control unit 280 predicts that there is a low possibility of a cleaning failure occurring in S1002, the process proceeds to S1003. In S1003, the predictive control unit 280 performs the image adjustment control described in the first embodiment in which patches are continuously formed and data is acquired from the second round onwards, and ends the predictive control.

[0067] If the prediction control unit 280 predicts in S1002 that there is a high possibility of a cleaning failure occurring, the process proceeds to S1004. In S1004, the prediction control unit 280 performs patch formation for the first round, for example, in the range from T1 to T2 in Fig. 5, using the patch formation control unit 230. In S1005, the prediction control unit 280 acquires patch data from the first round of patches formed in S1004 using the patch data acquisition unit 211 for color shift correction and the patch data acquisition unit 222 for density adjustment.

[0068] In S1006, the prediction control unit 280 controls the cleaning unit 270 to clean the intermediate transfer belt 12. By performing cleaning control at the timing of S1006 without forming (i.e., before forming) a patch for the second rotation, which would be wasted due to a decrease in detection accuracy caused by a cleaning failure, it is possible to further shorten the execution time.

[0069] 5. In S1008, the prediction control unit 280 acquires patch data from the second round of patches formed in S1007 by the patch data acquisition unit 211 for color shift correction and the patch data acquisition unit 222 for density adjustment. The engine control unit 204 combines the data from the first round acquired in S1005 and the data from the second round acquired in S1008 to perform image adjustment, thereby making it possible to maintain the accuracy of image adjustment even during cleaning failure prediction control.

[0070] In this way, when the predictive control unit 280 predicts that a cleaning defect will occur, the engine control unit 204 performs control as follows. The engine control unit 204 performs a first control to remove the remaining toner by the cleaning unit 270 (FIG. 10, S1006). When the predictive control unit 280 predicts that a cleaning defect will not occur, the engine control unit 204 performs control as follows. Since a cleaning defect will not occur, the engine control unit 204 does not clean the remaining toner, and performs a second control to form a patch included in a range longer than the circumferential length Lb (FIG. 10, S1003).

[0071] In other words, the engine control unit 204 performs the first image adjustment when the prediction control unit 280 predicts that the cleaning state is insufficient, and performs the second image adjustment when the prediction control unit 280 does not predict that the cleaning state is insufficient. The first image adjustment is image adjustment using a first adjustment pattern whose pattern length Lp and the circumference Lb have a relationship of Lp≦Lb. The second image adjustment is image adjustment using a second adjustment pattern whose pattern length Lp and the circumference Lb have a relationship of Lp>Lb. In the third embodiment, the retry control unit 250 also functions as an image adjustment retry unit that performs image adjustment again after performing the first image adjustment. The retry patch pattern has a pattern length Lp2, where Lp2 is a relationship of Lp2≦Lb with the circumference Lb. The retry patch pattern is a pattern that includes all patches that are not included in the first adjustment pattern among the patches included in the second adjustment pattern. The retry control unit 250 performs image adjustment using both the detection result of the immediately preceding first image adjustment and the detection result at the time of retry. The retry control unit 250 performs a cleaning operation to remove the patch pattern remaining on the intermediate transfer belt 12 by the cleaning unit, and then forms a patch pattern for retry.

[0072] As described above, in the third embodiment, the prediction control unit 280 predicts the cleaning status using at least one or more pieces of information among the lifespan of the intermediate transfer belt 12, the lifespan of the cleaning unit 270, and the detection result of the environment sensor 70 that measures the environment in which the image forming apparatus 201 is placed. The prediction control unit 280 may also predict the cleaning status using the most recent result detected by the detection control unit 240.

[0073] As described above, according to the third embodiment, by determining whether or not a cleaning defect occurs before controlling the image adjustment function, it is possible to reduce the execution time required for forming a patch for the second round, which would otherwise be wasted. In addition, since the patch data for the second round is acquired after cleaning control, it is possible to maintain the detection accuracy of the image adjustment function. Note that when the cleaning defect prediction control unit 280 predicts a cleaning defect, it is not necessary to form a patch for the second round, and image adjustment control may be performed using only the patch data for the first round.

[0074] Furthermore, the service life of the intermediate transfer belt 12 is determined based on the usage time of the intermediate transfer belt 12 and the cleaning unit 270, but it is also possible to use, for example, the rotation time of the intermediate transfer belt 12, the drive time of the motor that drives the intermediate transfer belt 12, or the cumulative number of prints of the paper P on which images have been formed. In other words, it is also possible to use information that is correlated with the service life of the intermediate transfer belt 12. Furthermore, the environmental sensor 70 detects the environmental temperature, but it is also possible to use other information, such as humidity or moisture content, as long as it is information that can cause cleaning defects.

[0075] As described above, according to the third embodiment, it is possible to reduce the execution time of the image adjustment operation while maintaining the detection accuracy.

[0076] The disclosure of this embodiment includes the following configuration. (Configuration 1) a forming means for forming an adjusting toner image including a plurality of toner images for adjusting an image density; an intermediate transfer body on whose surface the adjusting toner image is formed by the forming means; a detection unit for detecting the surface of the intermediate transfer body or the adjusting toner image; a control unit that performs image adjustment control including adjustment of the image density based on a result of detection of the adjusting toner image by the detection unit; An image forming apparatus comprising: the length from the leading toner image to the trailing toner image included in the adjustment toner image is longer than a circumferential length, which is a length in a transport direction of the intermediate transfer body, The image forming apparatus is characterized in that the control means forms a toner image included in the adjustment toner image, which is within a range shorter than the circumferential length, at a first density, and forms a toner image included in a range longer than the circumferential length at a second density darker than the first density, thereby performing the image adjustment control. (Configuration 2) When the plurality of toner images for adjusting the image density are defined as a first toner image group, The image forming apparatus according to any one of the above, wherein the adjusting toner images include a second toner image group including a plurality of toner images for adjusting color misregistration of a plurality of colors. (Configuration 3) a forming means for forming a toner image for adjustment, the toner image including a plurality of toner images for performing image adjustment; an intermediate transfer body on whose surface the adjusting toner image is formed by the forming means; a first detection unit that detects the surface of the intermediate transfer body or the adjusting toner image; a removing unit for removing the adjusting toner image on the intermediate transfer body; a control unit that performs image adjustment control based on a result of detection of the adjusting toner image by the first detection unit; An image forming apparatus comprising: a second detection unit that detects whether or not toner remains on the intermediate transfer body after the adjustment toner image is removed by the removing unit, the length from the leading toner image to the trailing toner image included in the adjustment toner image is longer than a circumferential length, which is a length in a transport direction of the intermediate transfer body, The image forming apparatus is characterized in that the control means detects whether or not toner remains using the second detection means after the removal means removes a toner image included in the adjustment toner image that is within a range shorter than the circumference. (Configuration 4) When the second detection means detects that toner remains on the intermediate transfer body, The above-mentioned image forming apparatus is characterized in that the control means removes the toner remaining on the intermediate transfer body using the removing means, and then causes the forming means to form a toner image of the adjustment toner image that is included in a range longer than the circumference. (Configuration 5) The above-mentioned image forming apparatus is characterized in that the control means performs the image adjustment control based on the result of detection by the first detection means of a toner image included in a range shorter than the circumference before removal by the removal means, and the result of detection by the first detection means of a toner image included in a range longer than the circumference formed by the formation means after the removal means removes the toner remaining on the intermediate transfer body. (Configuration 6) When the second detection means detects that toner remains on the intermediate transfer body, The above-mentioned image forming apparatus, characterized in that the control means performs the image adjustment control based on the result of detection by the first detection means of a toner image included in a range shorter than the circumference before it is removed by the removal means. (Configuration 7) a forming means for forming a toner image for adjustment, the toner image including a plurality of toner images for performing image adjustment; an intermediate transfer body on whose surface the adjusting toner image is formed by the forming means; a detection unit for detecting the surface of the intermediate transfer body or the adjusting toner image; a removing unit for removing the adjusting toner image on the intermediate transfer body; a control unit that performs image adjustment control based on a result of detection of the adjusting toner image by the detection unit; An image forming apparatus comprising: a predicting unit for predicting whether or not a cleaning defect will occur after the adjusting toner image formed on the intermediate transfer body is removed by the removing unit, the length from the leading toner image to the trailing toner image included in the adjustment toner image is longer than a circumferential length, which is a length in a transport direction of the intermediate transfer body, The control means when the prediction means predicts that the cleaning failure will occur, a first control is performed in which the removing means removes a toner image included in the adjustment toner image that is included in a range shorter than the circumferential length formed on the intermediate transfer body, and then the removing means removes toner remaining on the intermediate transfer body, and then the forming means forms a toner image included in the adjustment toner image that is included in a range longer than the circumferential length, When the prediction means predicts that the cleaning defect will not occur, a second control is performed in which a toner image included in the adjustment toner image and included in a range shorter than the circumferential length formed on the intermediate transfer body is removed by the removing means, and then a toner image included in the adjustment toner image and included in a range longer than the circumferential length is formed. 1. An image forming apparatus comprising: (Configuration 8) the adjusting toner image includes a plurality of toner images for adjusting an image density, The above-mentioned image forming device is characterized in that, in the second control, the control means forms a toner image included in the adjustment toner image that is within a range shorter than the circumferential length at a first density, and forms a toner image included in a range longer than the circumferential length at a second density that is darker than the first density, thereby performing the image adjustment. (Configuration 9) When the plurality of toner images for adjusting the image density are defined as a first toner image group, The image forming apparatus according to any one of the above, wherein the adjusting toner images include a second toner image group including a plurality of toner images for adjusting color misregistration of a plurality of colors. (Configuration 10) The above-mentioned image forming apparatus, characterized in that in the first control, the control means performs the image adjustment control based on the result of detection by the detection means of a toner image included in a range shorter than the circumference before removal by the removal means, and the result of detection by the detection means of a toner image included in a range longer than the circumference formed by the formation means after the removal means removes the toner remaining on the intermediate transfer body. (Configuration 11) The above-mentioned image forming apparatus, characterized in that in the first control, the control means performs the image adjustment control based on the detection result obtained by the detection means of the toner image included in a range shorter than the circumference before being removed by the removal means. (Configuration 12) A temperature detection means for detecting an environmental temperature; a life acquisition unit that acquires a life of the intermediate transfer body and / or the removal unit; Equipped with The image forming apparatus according to claim 1, wherein the prediction unit predicts whether or not the cleaning failure will occur based on at least one of the detection result of the temperature detection unit and the acquisition result of the life acquisition unit. [Explanation of symbols]

[0077] 4 Primary transfer roller 12 Intermediate transfer belt 22 Cartridge 50 Reflected light sensor 204 Engine control unit

Claims

1. a forming means for forming an adjusting toner image including a plurality of toner images for adjusting an image density; an intermediate transfer body on whose surface the adjusting toner image is formed by the forming means; a detection unit for detecting the surface of the intermediate transfer body or the adjusting toner image; a control unit that performs image adjustment control including adjustment of the image density based on a result of detection of the adjusting toner image by the detection unit; An image forming apparatus comprising: the length from the leading toner image to the trailing toner image included in the adjustment toner image is longer than a circumferential length, which is a length in a transport direction of the intermediate transfer body, The image forming apparatus is characterized in that the control means forms a toner image included in the adjustment toner image, which is within a range shorter than the circumference, at a first density, and forms a toner image included in a range longer than the circumference at a second density that is darker than the first density, thereby performing the image adjustment control.

2. When the plurality of toner images for adjusting the image density are defined as a first toner image group, 2. The image forming apparatus according to claim 1, wherein the adjusting toner images include a second toner image group including a plurality of toner images for adjusting color misregistration of a plurality of colors.

3. a forming means for forming a toner image for adjustment, the toner image including a plurality of toner images for performing image adjustment; an intermediate transfer body on whose surface the adjusting toner image is formed by the forming means; a first detection unit that detects the surface of the intermediate transfer body or the adjusting toner image; a removing unit for removing the adjusting toner image on the intermediate transfer body; a control unit that performs image adjustment control based on a result of detection of the adjusting toner image by the first detection unit; An image forming apparatus comprising: a second detection unit that detects whether or not toner remains on the intermediate transfer body after the adjusting toner image is removed by the removing unit, the length from the leading toner image to the trailing toner image included in the adjustment toner image is longer than a circumferential length, which is a length in a transport direction of the intermediate transfer body, The image forming apparatus is characterized in that the control means detects whether or not toner remains using the second detection means after the removal means removes the toner images contained in the adjustment toner image that are within a range shorter than the circumference.

4. When the second detection means detects that toner remains on the intermediate transfer body, 4. The image forming apparatus according to claim 3, wherein the control unit causes the removing unit to remove the toner remaining on the intermediate transfer body, and then causes the forming unit to form a toner image of the adjustment toner image that is included in a range longer than the circumference.

5. The image forming apparatus according to claim 4, characterized in that the control means performs the image adjustment control based on a result of detection by the first detection means of a toner image included in a range shorter than the circumference before removal by the removal means, and a result of detection by the first detection means of a toner image included in a range longer than the circumference formed by the formation means after the removal means removes the toner remaining on the intermediate transfer body.

6. When the second detection means detects that toner remains on the intermediate transfer body, 4. The image forming apparatus according to claim 3, wherein the control means performs the image adjustment control based on a result of detection by the first detection means of a toner image included in an area shorter than the circumference before being removed by the removal means.

7. a forming means for forming a toner image for adjustment, the toner image including a plurality of toner images for performing image adjustment; an intermediate transfer body on whose surface the adjusting toner image is formed by the forming means; a detection unit for detecting the surface of the intermediate transfer body or the adjusting toner image; a removing unit for removing the adjusting toner image on the intermediate transfer body; a control unit that performs image adjustment control based on a result of detection of the adjusting toner image by the detection unit; An image forming apparatus comprising: a predicting unit for predicting whether or not a cleaning defect will occur after the adjusting toner image formed on the intermediate transfer body is removed by the removing unit, the length from the leading toner image to the trailing toner image included in the adjustment toner image is longer than a circumferential length, which is a length in a transport direction of the intermediate transfer body, The control means when the predicting means predicts that the cleaning failure will occur, a first control is performed in which the removing means removes the toner remaining on the intermediate transfer body, and then the forming means forms a toner image of the adjusting toner image that is included in a range longer than the circumferential length, When the predicting means predicts that the cleaning defect will not occur, a second control is performed to form a toner image included in the adjustment toner image, the toner image being included in a range longer than the circumferential length.

1. An image forming apparatus comprising:

8. the adjusting toner image includes a plurality of toner images for adjusting an image density, The image forming apparatus according to claim 7, characterized in that, in the second control, the control means forms a toner image included in the adjustment toner image that is within a range shorter than the circumferential length at a first density, and forms a toner image included in a range longer than the circumferential length at a second density that is darker than the first density, thereby performing the image adjustment.

9. When the plurality of toner images for adjusting the image density are defined as a first toner image group, 9. The image forming apparatus according to claim 8, wherein the adjusting toner images include a second toner image group including a plurality of toner images for adjusting color misregistration of a plurality of colors.

10. The image forming apparatus according to claim 7, characterized in that, in the first control, the control means performs the image adjustment control based on the result of detection by the detection means of a toner image included in a range shorter than the circumference before removal by the removal means, and the result of detection by the detection means of a toner image included in a range longer than the circumference formed by the formation means after the removal means removes the toner remaining on the intermediate transfer body.

11. The image forming apparatus according to claim 7, wherein the control means performs the image adjustment control in the first control based on a result of detection by the detection means of a toner image included in a range shorter than the circumference before being removed by the removal means.

12. A temperature detection means for detecting an environmental temperature; a life acquisition unit that acquires a life of the intermediate transfer body and / or the removing unit; Equipped with 12. The image forming apparatus according to claim 7, wherein the prediction unit predicts whether or not the cleaning failure will occur based on at least one of the detection result of the temperature detection unit and the acquisition result of the life acquisition unit.

Images