JP6722057B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

In the image forming apparatus, for example, in order to maintain image quality, image adjustment control is performed when the power is turned on. Generally, image formation cannot be performed unless the image adjustment control is completed, and thus it is required to reduce the time required for the image adjustment control. Patent Document 1 discloses a configuration in which a test pattern for positional deviation correction and color correction is formed at the same scanning position on the same photoconductor to reduce the time for image adjustment control.

In a color image forming apparatus, a plurality of colors used for image formation, for example, yellow, magenta, cyan, and black toner images are respectively formed on corresponding photoconductors, and these are used as recording materials or intermediate transfer bodies. There is one that forms a color toner image by transferring. Patent Document 2 discloses that in such an image forming apparatus, the diameter of a photosensitive member that forms a black toner image is made larger than that of a photosensitive member that forms another color. This is to address the problem that the photoconductor that forms a black toner image is used both when forming a monochrome image and when forming a color image, and has a shorter life than other photoconductors.

JP, 2008-281864, A JP, 10-78708, A

When the sizes of the yellow, magenta, and cyan photoconductors and the black photoconductor are different, the materials of the respective photoconductors may be different. Further, the presence or absence of a sensor or the like may be different due to the arrangement space of each component. Therefore, different image adjustment control may be performed for each of the yellow, magenta, and cyan image forming units and the black image forming unit. When different image adjustment controls are performed by the image forming units having different configurations, the number of adjustment items increases and the image adjustment control time becomes long.

The present invention provides an image forming apparatus that performs image adjustment control in a short time.

According to an aspect of the present invention, an image forming apparatus forms a first photoconductor and a first electrostatic latent image on the first photoconductor, and develops the first electrostatic latent image with toner of a first color. To form a first image, a second photoconductor, and a second electrostatic latent image is formed on the second photoconductor, and the second electrostatic latent image is converted to the first color. A second image forming means for developing with a different second color toner to form a second image, and an intermediate portion to which the first image of the first photoconductor and the second image of the second photoconductor are transferred. The transfer body, the detection means for detecting the surface potential of the first photoconductor, and the first image forming means are caused to form an electrostatic latent image for measurement on the first photoconductor, and the detection means is caused to perform the measurement. Adjusting means for detecting the surface potential of the first photoconductor on which the electrostatic latent image for use is formed, and adjusting the image forming condition of the first image forming means based on the detection result of the detecting means; A light emitting means for emitting light to be radiated toward the transfer body; a measuring means for causing the light emitting means to emit light and measuring reflected light from a surface of the intermediate transfer body or an image formed on the intermediate transfer body; The second image forming means forms a measurement image on the intermediate transfer member, causes the measurement means to measure the reflected light from the measurement image, and based on the measurement result of the measurement means, Deciding means for deciding the light emission intensity, wherein the deciding means is arranged such that the adjusting means makes the first image forming means start the formation of the electrostatic latent image for measurement on the first photoconductor. It is characterized in that the measurement image is formed on the second image forming means until the image forming condition is adjusted.

According to the present invention, image adjustment control can be performed in a short time.

1 is a configuration diagram of an image forming apparatus according to an embodiment. FIG. 3 is a control configuration diagram of the image forming apparatus according to the embodiment. FIG. 3 is an explanatory diagram of a potential of a photoconductor according to one embodiment. FIG. 6 is a diagram showing a test pattern for color misregistration correction control according to an embodiment. FIG. 6 is an explanatory diagram of color misregistration amount detection according to an embodiment. 1 is a configuration diagram of a photo sensor according to an embodiment. Explanatory drawing of the light emission intensity control by one Embodiment. FIG. 6 is an explanatory diagram of background correction control according to an embodiment. 6 is a flowchart of image adjustment control according to an embodiment. 6 is a flowchart of potential control according to one embodiment. 6 is a timing chart of image adjustment control according to an embodiment.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. The following embodiments are exemplifications, and the present invention is not limited to the contents of the embodiments. Further, in each of the following drawings, components that are not necessary for explaining the embodiment are omitted from the drawings.

FIG. 1 is a schematic sectional configuration diagram of the image forming apparatus according to the present embodiment. The image forming apparatus includes image forming units Pa, Pb, Pc, and Pd that form yellow, magenta, cyan, and black toner images and transfer the toner images to the intermediate transfer belt 181. It should be noted that the same reference numerals of different numbers are used for the same components of the image forming units Pa, Pb, Pc, and Pd, except for the alphabet at the end. Further, in the following description, when it is not necessary to distinguish between colors, reference numerals excluding the alphabet at the end are used. The photoconductor 101a of the image forming portion Pa is rotationally driven in the counterclockwise direction in the drawing during image formation. The charging unit 122a charges the surface of the rotationally driven photoconductor 101a to a uniform potential. The exposure unit 111a exposes the photoconductor 101a to form an electrostatic latent image on the surface of the photoconductor 101a. The developing unit 123a attaches yellow toner to the electrostatic latent image on the photoconductor 101a, thereby forming a yellow toner image. The primary transfer roller 124a transfers the yellow toner image to the intermediate transfer belt 181. The cleaning unit 112a removes the toner that is not transferred to the intermediate transfer belt 181 and remains on the photoconductor 101a. The same applies to the image forming portions Pb and Pc except for the color of the toner.

The photoconductor 101d of the black image forming portion Pd is also rotationally driven in the counterclockwise direction in the drawing during image formation. In this embodiment, the diameter of the photoconductor 101d is larger than the diameters of the photoconductors 101a, 101b, and 101c. The charging unit 138 of the image forming unit Pd charges the surface of the rotationally driven photoconductor 101d to a uniform potential. Here, the configuration of the charging unit 138 of the image forming unit Pd of the present embodiment is different from the configurations of the charging units 122a, 122b, and 122c of the other image forming units Pa, Pb, and Pc. The exposure unit 111d exposes the photoconductor 101d to form an electrostatic latent image on the surface of the photoconductor 101d. The developing unit 123d attaches black toner to the electrostatic latent image on the photoconductor 101d, thereby forming a black toner image. The primary transfer roller 124d transfers the black toner image to the intermediate transfer belt 181. The black image forming portion Pd includes a potential sensor 135 that measures the surface potential of the photoconductor 101d. It should be noted that a full-color toner image is formed on the intermediate transfer belt 181, by superimposing the toner images of the respective colors formed on the respective photoconductors 101 and transferring them to the intermediate transfer belt 181.

The intermediate transfer belt 181 is an intermediate transfer member, is stretched by rollers 125, 126, 127, 128, and 129, and is driven to rotate in the direction of arrow X depending on the rotation of the roller 125 during image formation. Therefore, the toner images transferred by the image forming units Pa, Pb, Pc, and Pd are conveyed to the position facing the secondary transfer roller 140 as the intermediate transfer belt 181 rotates. The sheet P, which is the recording material stored in the paper feed cassette 160, reaches the opposing position of the secondary transfer roller 140 at the timing when the toner image of the intermediate transfer belt 181 reaches the opposing position of the secondary transfer roller 140. Be transported. Then, the secondary transfer roller 140 transfers the toner image on the intermediate transfer belt 181 to the sheet P. The toner that is not transferred to the sheet P and remains on the intermediate transfer belt 181 is removed by the cleaning units 116a and 116b. The sheet P on which the toner image is transferred is then conveyed to the fixing unit 113. The fixing unit 113 heats and pressurizes the sheet P, thereby fixing the toner image on the sheet P. The sheet P on which the toner image has been fixed is then discharged to the outside of the image forming apparatus. A photo sensor 109 that detects a test pattern in color misregistration correction control is provided at a position facing the intermediate transfer belt 181.

In the present embodiment, the configurations of the image forming portions Pa, Pb, and Pc that form toner images of chromatic colors, that is, yellow, magenta, and cyan, and the image forming portion Pd that form a toner image of achromatic colors, that is, black, are different. Specifically, as described above, in this embodiment, the diameter of the photoconductor 101d is larger than the diameters of the photoconductors 101a, 101b, and 101c. As an example, the outer diameter of the photoconductor 101d is 80 [mm], and the outer diameter of the photoconductors 101a, 101b, and 101c is 30 [mm]. Further, as described above, the configuration of the charging unit 138 of the image forming unit Pd is different from the configuration of the charging units 122a, 122b, 122c of the image forming units Pa, Pb, Pc. In the present embodiment, the charging units 122a, 122b, 122c are contact charging units that contact and charge the surfaces of the photoconductors 101a, 101b, 101c, respectively. On the other hand, the charging unit 138 of the image forming unit Pd includes a charger and a grid plate, and charges the photoconductor 101d with a bias output from the grid plate without contacting the surface of the photoconductor 101d. It is a non-contact charging section.

FIG. 2 is a diagram showing a control configuration of the image forming apparatus. The system controller 200 is a control unit that totally controls the image forming apparatus. The CPU 201 of the system controller 200 executes programs stored in the ROM 202 to perform various controls on the image forming apparatus. Further, the CPU 201 uses the RAM 203 to store data necessary for controlling the image forming apparatus. The operation unit 20 allows the user to operate the image forming apparatus and displays the state of the image forming apparatus to the user. That is, the operation unit 20 provides an input/output interface function with the user.

The pattern forming unit 213 includes a test pattern (measurement image) for color misregistration correction control described later, a test pattern (measurement image) for emission intensity control of the photosensor 109, and a test pattern (measurement image) for background correction. Image) is formed. The photosensor 109 irradiates the intermediate transfer belt 181 with light, receives the reflected light from the surface and the test pattern formed by the pattern forming unit 213, and outputs a signal according to the received light intensity. As a result, the pattern reading unit 214 reads the test pattern formed on the intermediate transfer belt 181 by the pattern forming unit 213. The environment sensor 224 acquires environment information such as temperature and humidity inside the image forming apparatus.

The image forming apparatus performs image adjustment control to prevent image defects due to environmental changes and deterioration of each member. In the present embodiment, in this image adjustment control, the potential control of the photoconductor 101d, the emission intensity control of the photosensor 109, the background supplement control, and the color misregistration correction control are performed. Hereinafter, each control will be described in order.

First, the potential control of the photoconductor 101d will be described. FIG. 10 is a flowchart of potential control. In step S20, the CPU 201 causes the grid plate of the charging unit 138 to output the initial bias Vg_rgh. The initial bias Vg_rgh is determined based on the environmental information at the time of potential control acquired by the environmental sensor 224. Specifically, first, the target potential Vd_target at the developing position of the developing unit 123d and the dark attenuation amount EPCatt are determined based on the environmental information during the potential control. The relationship between the value of the environmental information and the target potential and dark attenuation amount at the developing position is determined in advance and stored in, for example, the ROM 202. The dark attenuation amount is the amount of change in the potential of the photoconductor 101d between the potential measurement position by the potential sensor 135 and the developing position by the developing unit 123d. Then, the target potential EPCsens of the potential sensor 135 is
EPCsens=Vd_target-EPCatt
Ask by. Then, a value obtained by adding a predetermined dark attenuation amount (Att) to the target potential EPCsens is set as the initial bias Vg_rgh. That is, the initial bias Vg_rgh is
Vg_rgh=EPCsens+Att
Ask as. Note that Att is the difference between the potential output by the grid plate and the potential at the measurement position of the potential sensor 135 of the photoconductor 101d charged by this potential.

In step S21, the CPU 201 detects the potential of the surface of the photoconductor 101d using the potential sensor 135. Then, in S22, the CPU 201 determines the grid bias Vg by using the detection result in S21. Specifically, if the surface potential of the photoconductor 101d detected in S21 is V1, the grid bias Vg is determined by the following equation.
Vg=Vg_rgh+(EPCsens−V1)×(Vg_rgh)/EPCsens
The charging unit 138 outputs the grid bias Vg, so that the surface potential Vd at the developing position of the photoconductor 101d becomes the target potential Vd_target.

After that, in S23, the charging unit 138 outputs the grid bias Vg determined in S22 to charge the photoconductor 101d, and exposes the surface of the charged photoconductor 101d while changing the light intensity of the exposure unit 111d. That is, a measurement electrostatic latent image for potential control is formed on the photoconductor 101d. In S24, the CPU 201 measures and detects the potential of the electrostatic latent image for measurement of the photoconductor 101d by the potential sensor 135, and in S25, based on the detection result of S24, the light intensity of the exposure section 111d and the surface of the photoconductor 101d. Find the relationship with the potential. In the following description, the correspondence relationship between the light intensity of the exposed portion 111d and the surface potential of the photoconductor 101d is called an EV curve. Then, in S26, the CPU 201 determines the image forming condition of the image forming unit Pd. Specifically, the exposure portion potential of the photoconductor 101d, that is, the exposure intensity with the potential of the exposure region as the target potential Vl is determined. The target potential Vl is calculated by the following formula.
Vl=EPCsens+Vback+Vcont

Note that Vback and Vcont are determined based on the environmental state acquired by the environmental sensor 224 during potential control. Therefore, the relationship between the environmental state and Vback and Vcont is determined in advance and stored in, for example, the ROM 202. Further, the CPU 201 sets the absolute value, which is lower than the potential Vd by Vback, as the developing bias Vdc output from the developing unit 123d. FIG. 3 shows the relationship of each potential. By charging the photoconductor 101d with the grid bias Vg, the potential at the developing position on the surface of the photoconductor 101d becomes Vd. A potential lower than the charging potential Vd by Vback is set as the developing bias Vdc output by the developing unit 123d. A potential lower than the developing bias Vdc by Vcont becomes Vl. Thus, the potential control is adjustment control of image forming conditions for adjusting the charging potential of the photoconductor 101d, the exposure intensity of the exposure unit 111d, and the developing bias of the developing unit 123d as the image forming conditions of the image forming unit Pd.

Subsequently, the color misregistration correction control will be described. In the image forming apparatus, due to temperature rise in the image forming apparatus due to image formation and changes in the installation environment, the exposure position for each photoconductor 101 changes, causing so-called color misregistration. Therefore, the image forming apparatus performs color misregistration correction control. FIG. 4 shows a test pattern formed on the intermediate transfer belt 181 in the color misregistration correction control. As shown in FIG. 4, in this embodiment, three photosensors 109a, 109b, and 109c are provided at different positions in the main scanning direction of the intermediate transfer belt 181. The main scanning direction is a direction orthogonal to the conveyance direction of the intermediate transfer belt 181, that is, the left-right direction in FIG. The transport direction of the intermediate transfer belt 181 is also referred to as a sub-scanning direction below. Note that, as shown in FIGS. 1 and 2, when it is not necessary to distinguish the three photosensors 109a, 109b, and 109c, they are collectively referred to as the photosensor 109. In this embodiment, the test patterns detected by the three photosensors 109a, 109b, and 109c are the same pattern.

In the test pattern shown in FIG. 4, reference numerals 300Ya and 300Yb are yellow toner images, and reference numerals 300Ca and 300Cb are cyan toner images. Reference numerals 300Ka1, 300Ka2, 300Kb1, and 300Kb2 are black toner images, and reference numerals 300M to 307M, 300Mak, and 300Mbk are magenta toner images. In this embodiment, magenta is used as the reference color, and the relative color shift amount of another color with respect to magenta is calculated. In the test pattern of FIG. 4, the black toner images 300Ka1 and 300Ka2 are formed on the magenta toner image 300Mak so as to partially overlap the magenta toner image 300Mak. Specifically, the end face of the magenta toner image 300Mak in the transport direction of the intermediate transfer belt 181 is at the position indicated by the dotted line, and black toner images 300Ka1 and 300Ka2 are formed thereon as shown in FIG. There is. The same applies to the toner image 300Mbk. This is because the color of the surface of the intermediate transfer belt 181 of the present embodiment is black, and when a black toner image is formed independently, the difference between the reflected light from the black toner image and the reflected light from the intermediate transfer belt 181. Is very small. That is, when the black toner image is formed alone, the position of the black toner image cannot be detected with high accuracy. Therefore, in the present embodiment, the position of the black toner image is specified by superimposing the black toner image on the magenta toner image of the reference color and detecting the boundary between black and magenta.

FIG. 5 is an explanatory diagram of a method for detecting the amount of yellow color shift with respect to magenta. FIG. 5 also shows a waveform obtained by binarizing the output of the photo sensor 109 with a threshold value. The threshold value is stored in the pattern reading unit 214. In FIG. 5, reference numeral 301Ya is the distance between the magenta toner image 300M and the yellow toner image 300Ya, and reference numeral 302Ya is the distance between the yellow toner image 300Ya and the magenta toner image 301M. Similarly, reference numeral 301Yb is the distance between the magenta toner image 304M and the yellow toner image 300Yb, and reference numeral 302Yb is the distance between the yellow toner image 300Yb and the magenta toner image 305M. As is clear from FIG. 5, when the yellow toner image shifts to the left side of the figure with respect to the magenta toner image, the distances 302Ya and 301Yb increase and the distances 301Ya and 302Yb decrease. When each toner image is formed at an angle of 45 degrees with respect to the transport direction, the increase/decrease amount of the distances 301Ya, 302Ya, 301Yb, and 302Yb is equal to the color misregistration amount of yellow with respect to magenta in the main scanning direction. Therefore, the amount of color misregistration in the main scanning direction can be calculated by the following formula.
{(302Ya-301Ya)/2+(301Yb-302Yb)/2}/2
The amount of color misregistration in the sub-scanning direction can be calculated by the following formula.
{(302Ya-301Ya)/2+(302Yb-301Yb)/2}/2
The same applies to cyan and black.

For example, a plurality of test patterns shown in FIG. 5 are formed over the circumference of the intermediate transfer belt 181 along the transport direction. Then, the CPU 201 obtains an average value of each color shift amount in the main scanning direction and the sub scanning direction obtained for each test pattern, and controls the image forming condition relating to the color shift.

Next, the emission intensity control of the photo sensor 109 will be described. FIG. 6 is a configuration diagram of the photo sensor 109. The light emitting unit 151 emits light toward the intermediate transfer belt 181. Of the irradiated light, the reflected light at the detection area 154 is condensed by the lens 153 and enters the light receiving portion 152. In the present embodiment, the light receiving unit 152 is provided so as to receive irregularly reflected light on the surface of the intermediate transfer belt 181 or the test pattern formed on the intermediate transfer belt 181. The detection signal corresponding to the received light intensity output by the light receiving unit 152 is binarized by being compared with a threshold value by the pattern reading unit 214. If the peak value of the detection signal is low, the test pattern cannot be correctly detected in the color misregistration correction control. Therefore, in this embodiment, the light emission intensity of the light emitting unit 151 is controlled.

FIG. 7 is an explanatory diagram of the emission intensity control of the photo sensor 109. First, the CPU 201 forms the test pattern shown in FIG. 7 on the intermediate transfer belt 181. In FIG. 7, reference numerals 350M, 350C, and 350Y are magenta, cyan, and yellow toner images, respectively. The CPU 201 drives the light emitting unit 151 with a predetermined reference voltage to cause the light emitting unit 151 to emit light, and acquires the detection signal output by the light receiving unit 152 when the reflected light of the toner image of each color is received. Then, the one having the lowest peak value of the detection signal corresponding to the reflected light from the toner images of the three colors is determined. The solid line in FIG. 7 shows this peak value. The peak value of the reflected light from the toner images 350M and 350Y is about 0.8V, and the peak value of the reflected light from the toner image 350C is about 0.5V. is there. Then, the CPU 201 adjusts the drive voltage of the light emitting unit 151 so that the lowest peak value becomes the target value. In the example of FIG. 7, this target value is 1V. The dotted line in FIG. 7 shows the peak value of the reflected light from each toner image after the emission intensity adjustment. The peak value of the reflected light from the toner image 350C having the lowest peak value before the emission intensity control is 1V which is the target value. Therefore, the peak value of the reflected light from the other toner images is higher than the target value of 1V. As described above, the emission intensity control of the present embodiment is determination control that determines the emission intensity of the light emitting unit 151.

Next, the background correction control will be described. As described with reference to FIG. 5, in the test pattern for the color misregistration correction control of the present embodiment, the black toner image is formed on the magenta toner image. The light receiving unit 152 of the photo sensor 109 of the present embodiment receives irregularly reflected light. Since the intensity of diffused reflection light from the black and magenta toner images is different, the CPU 201 can detect the boundary between the black toner image and the magenta toner image. However, when the black density decreases, the magenta toner image thereunder becomes transparent, which also increases the intensity of diffused reflection light from the black portion. Therefore, in order to determine the threshold value for detecting the boundary between black and magenta, it is necessary to grasp the level of the detection signal output from the photosensor 9 while receiving the reflected light from the superimposed portion of magenta and black. .. Therefore, in the present embodiment, the background correction control is executed.

In the background correction control, for example, like the toner images 300MaK, 300Ka1 and 300Ka2 in FIG. 4, a superposed image in which a black toner image is superimposed on a magenta toner image is formed. FIG. 8A shows a detection signal when the black density is high. In this example, when the black density is high, the intensity of irregularly reflected light on black is lower than the intensity of irregularly reflected light on the surface of the intermediate transfer belt 181. On the other hand, FIG. 8B shows a detection signal when the black density becomes low. As shown in FIG. 8B, when the black density is low, the level of the detection signal when the reflected light from the black portion is received becomes high. Therefore, the threshold value for detecting the boundary between magenta and black is also determined according to the peak value of the detection signal when the reflected light from the black portion is received. For example, the threshold in the state of FIG. 8(B) is set higher than the threshold in the state of FIG. 8(A).

In this embodiment, when the power of the image forming apparatus is turned on, the image adjustment control is performed in consideration of the environmental fluctuation during the period when the power is not turned on. FIG. 9 is a flowchart of this image adjustment control. First, in S10, the CPU 201 starts the potential control shown in FIG. 10 and the light emission intensity control of the photo sensor 109 in parallel. Subsequently, in S11, the CPU 201 determines the light emission intensity of the photo sensor 109 based on the result of the light emission intensity control. After that, in S12, the CPU 201 causes the photo sensor 109 to emit light, and causes the photo sensor 109 to receive the reflected light from the surface of the intermediate transfer belt 181, and thereby the photo sensor 109 when the surface of the intermediate transfer belt 181 is detected. Measure the level of the detection signal of. This is to detect the intensity of irregularly reflected light on the intermediate transfer belt 181, as shown in FIG.

The potential control started in S10 is performed only for the image forming unit Pd. As described with reference to FIG. 7, the emission intensity control of the photo sensor 109 forms yellow, cyan, and magenta toner images, but does not form black toner images. Further, the process of S12 does not form an image. Therefore, the potential control can be performed in parallel with the light intensity control and the detection of the surface of the intermediate transfer belt 181.

After that, in S13, the CPU 201 determines whether or not the potential control is completed, and if not completed, waits until it is completed. When the potential control is completed, the CPU 201 forms a superimposed image for background correction, that is, an image in which a black toner image is superposed on a magenta toner image in the present embodiment in S14, and the photo sensor 109 forms the superimposed image. The level of the detection signal corresponding to the diffusely reflected light from is measured. Then, the CPU 201 determines the threshold value for boundary detection based on the level of the detection signal in S12 and the level of the detection signal in S14, as described in FIG. Note that, for example, when the level of the detection signal in S14 is lower than the detection signal level in S12, the threshold value is set to the first threshold value. For example, the CPU 201 sets the value obtained by adding a predetermined level to the detection signal level in step S12 as the first threshold value. On the other hand, when the level of the detection signal in S14 is higher than the level of the detection signal in S12, the threshold value is set to the second threshold value. The CPU 201 sets, for example, a value obtained by adding a predetermined level to the detection signal level in step S14 as the second threshold value. The second threshold is a value larger than the first threshold. Alternatively, when the level of the detection signal in S14 is higher than the level of the detection signal in S12, the threshold value may be set according to the difference.

After that, the CPU 201 starts the color misregistration correction control in S16 and waits until the color misregistration correction control is completed in S17. In the color misregistration correction control, as described with reference to FIG. 5, the relative color misregistration amount of the other color with respect to the reference color is obtained in each of the main scanning direction and the sub scanning direction. Then, the CPU 201 controls the image forming conditions based on the amount of color misregistration in each of the main scanning direction and the sub scanning direction. The image forming conditions are conditions for correcting the main-scanning writing position of each color, the magnification in the main-scanning direction, the writing position in the sub-scanning direction, the inclination with respect to the sub-scanning direction, and the like.

FIG. 11 is an example of a timing chart of image adjustment control at power-on in the present embodiment. In this embodiment, the image forming conditions of the image forming portion Pd are determined and adjusted by controlling the potential. Then, the CPU 201 forms a test pattern for light intensity control until the image forming conditions of the image forming portion Pd are adjusted. Further, the CPU 201 completes the determination of the light emission intensity of the light emitting unit 151 of the photo sensor 109 before adjusting the image forming conditions of the image forming unit Pd. Further, when the CPU 201 determines the light emission intensity of the light emitting unit 151 of the photo sensor 109, it starts measuring the intensity of the reflected light from the surface of the intermediate transfer belt 181, that is, the background measurement. In the example of FIG. 11, the CPU 201 completes the measurement of the intensity of the reflected light from the surface of the intermediate transfer belt 181 until the image forming conditions of the image forming unit Pd are adjusted. After that, the CPU 201 forms a superimposed image in which the black toner image is superimposed on the magenta toner image in the image forming portions Pb and Pd in this example, and measures the reflected light from the superimposed image, that is, the background measurement. Start. Then, the CPU 201 determines a threshold value for detecting the boundary between magenta and black based on the measurement result of the reflected light from the superimposed image, and starts the color misregistration correction control using this threshold value. That is, the CPU 201 functions as a threshold value determining unit.

As described above, even when different image adjustment controls are performed in the image forming units having different configurations, it is possible to reduce the time required for the image adjustment control by performing some image adjustment controls in parallel.

[Other Embodiments]
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program. It can also be realized by the processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

101a to 101d: photoconductor, Pa to Pd: image forming unit, 181: intermediate transfer belt, 135: potential sensor, 201: CPU, 151: light emitting unit, 152: light receiving unit, 109: photo sensor

Claims (12)

A first photoconductor,
First image forming means for forming a first electrostatic latent image on the first photoconductor and developing the first electrostatic latent image with toner of a first color to form a first image;
A second photoconductor,
Second image formation in which a second electrostatic latent image is formed on the second photoconductor and the second electrostatic latent image is developed with a toner of a second color different from the first color to form a second image. Means and
An intermediate transfer member onto which the first image of the first photoconductor and the second image of the second photoconductor are transferred;
Detection means for detecting the surface potential of the first photoconductor,
The first image forming unit forms a measurement electrostatic latent image on the first photoconductor, and the detection unit detects the surface potential of the first photoconductor on which the measurement electrostatic latent image is formed. Adjusting means for adjusting the image forming condition of the first image forming means based on the detection result of the detecting means,
A light emitting means for emitting light to be radiated toward the intermediate transfer member,
Measuring means for causing the light emitting means to emit light, and measuring reflected light from the surface of the intermediate transfer member or an image formed on the intermediate transfer member;
The second image forming means forms a measurement image on the intermediate transfer member, the measurement means measures the reflected light from the measurement image, and based on the measurement result of the measurement means, the light emitting means. Determining means for determining the emission intensity of
The deciding means sets the first image forming means between the start of the formation of the measuring electrostatic latent image on the first photoconductor and the adjustment means adjusting the image forming condition. 2. An image forming apparatus, wherein the image forming unit forms the measurement image. The image forming apparatus according to claim 1, wherein the first color is an achromatic color and the second color is a chromatic color. The determining unit is configured to emit the light during a period from when the first image forming unit starts forming the measuring electrostatic latent image on the first photoconductor to when the adjusting unit adjusts the image forming condition. The image forming apparatus according to claim 1, wherein the light emission intensity of the means is determined. 4. The substrate measuring means for causing the measuring means to measure the reflected light from the surface of the intermediate transfer body when the determining means determines the emission intensity of the light emitting means. The image forming apparatus according to claim 1. The background measuring unit is configured to perform the operation between the first image forming unit starting to form the measuring electrostatic latent image on the first photosensitive member and the adjusting unit adjusting the image forming condition. The image forming apparatus according to claim 4, wherein the measurement of the reflected light from the surface of the intermediate transfer member is completed. When the determining unit determines the light emission intensity of the light emitting unit and the adjusting unit adjusts the image forming condition, a superimposed image in which the first image is superposed on the second image is formed on the first image forming unit and the second image forming unit. 4. A substrate measuring unit which is formed on the intermediate transfer member by the second image forming unit, and the measuring unit is further provided with a background measuring unit for measuring reflected light from the superimposed image. 2. The image forming apparatus according to item 1. The image forming apparatus further comprises threshold value determining means for determining a threshold value for detecting the boundary between the first image and the second image in the color misregistration correction control based on the measurement result of the reflected light from the superimposed image by the background measuring means. The image forming apparatus according to claim 6, wherein. 8. The measuring means further comprises a light receiving means for receiving diffused reflected light from the surface of the intermediate transfer body or an image formed on the intermediate transfer body. The image forming apparatus according to item 1. The first image forming unit uses a charging unit that charges the first photoconductor, an exposure unit that exposes the charged first photoconductor, and the first electrostatic latent image with the toner of the first color. Developing means for developing,
9. The image forming apparatus according to claim 1, wherein the image forming condition is a surface potential of the first photoconductor charged by the charging unit. The first image forming unit uses a charging unit that charges the first photoconductor, an exposure unit that exposes the charged first photoconductor, and the first electrostatic latent image with the toner of the first color. Developing means for developing,
The image forming apparatus according to claim 1, wherein the image forming condition is an exposure intensity of the exposing unit. The first image forming unit uses a charging unit that charges the first photoconductor, an exposure unit that exposes the charged first photoconductor, and the first electrostatic latent image with the toner of the first color. Developing means for developing,
The image forming apparatus according to claim 1, wherein the image forming condition is a developing bias of the developing unit. A first photoconductor,
First image forming means for forming a first electrostatic latent image on the first photoconductor and developing the first electrostatic latent image with toner of a first color to form a first image;
A second photoconductor,
Second image formation in which a second electrostatic latent image is formed on the second photoconductor and the second electrostatic latent image is developed with a toner of a second color different from the first color to form a second image. Means and
An intermediate transfer member onto which the first image of the first photoconductor and the second image of the second photoconductor are transferred;
Detection means for detecting the surface potential of the first photoconductor,
The first image forming unit forms a measurement electrostatic latent image on the first photoconductor, and the detection unit detects the surface potential of the first photoconductor on which the measurement electrostatic latent image is formed. Adjusting means for performing adjustment control for adjusting the image forming condition of the first image forming means based on the detection result of the detecting means,
A light emitting means for emitting light to be radiated toward the intermediate transfer member,
Measuring means for causing the light emitting means to emit light, and measuring reflected light from the surface of the intermediate transfer member or an image formed on the intermediate transfer member;
The second image forming means forms a measurement image on the intermediate transfer member, the measurement means measures the reflected light from the measurement image, and based on the measurement result of the measurement means, the light emitting means. And a determination means for performing determination control for determining the emission intensity of
An image forming apparatus, wherein a period during which the determination control is performed by the determination unit has a period that overlaps with a period during which the adjustment control is performed by the adjustment unit.

Images