JP7207971B2 - image forming device - Google Patents

Description

The present invention relates to an image forming apparatus capable of outputting a test chart for adjusting transfer voltage.

Conventionally, an electrophotographic image forming apparatus has a problem that a desired toner image cannot be formed on an image carrier due to changes in the usage environment of the apparatus main body and durability conditions. To solve this problem, after forming a specific test chart on the recording material, the user adjusts the transfer voltage based on the patch image information selected from the test chart formed on the recording material. , methods have been proposed to improve the stability of image quality.

FIG. 10 shows an example of a conventional transfer voltage adjustment test chart.

The patch image of the test chart 500 is a monochromatic solid image formed on the recording material by switching the transfer voltage, and the respective colors of yellow (Y), magenta (M), cyan (C), and black (K) are printed. They are arranged along the traveling direction of the recording material.

The secondary transfer voltage is changed so that the voltage value supplied to the secondary transfer roller is changed stepwise in accordance with the timing at which each patch image is transferred to the recording material by the secondary transfer roller.

Numerical values in seven stages from -3 to +3 in FIG. 10 indicate levels of voltage values supplied to the secondary transfer roller.

When the user selects the numerical value written on the left side of the patch image that the user has judged to be optimal because there are no problems such as defective images or insufficient density, and inputs the numerical value from the operation panel, the image forming apparatus to execute the transfer voltage adjustment control.

FIG. 11 is a diagram showing the relationship between the pitch of a conventional patch image and the secondary transfer voltage.

A secondary transfer voltage with a predetermined amount (.DELTA.150 V in FIG. 11) changed stepwise for each patch image along the traveling direction of the recording material is applied to form a toner image of the patch on the recording material.

Switching of the secondary transfer voltage for each patch image is performed from the trailing edge of each patch image, and it is necessary to converge the secondary transfer voltage to the target value by the leading edge of the next patch.

In the case of FIG. 11, the process speed (hereinafter referred to as PS)=500 mm/s, the patch interval is 10 mm, and the secondary transfer output voltage must be converged within 20 ms (=10 mm/50 mm/s).

JP-A-2000-221803

FIG. 12 is a diagram showing the relationship between a conventional secondary transfer voltage and a patch image.

As shown in the figure, in the conventional example, the secondary transfer voltage is increased by a predetermined amount ΔV between adjacent patches. The secondary transfer voltage target value at the time of formation is a value (V6) increased by ΔV from V5.

If the secondary transfer voltage value does not converge to V6 by the leading edge position of the patch image on the right side of FIG. 12, an image defect occurs at the leading edge of the patch image due to insufficient secondary transfer voltage, and the user selects the optimum patch image. may not be possible.

Therefore, it is necessary to set the interval between each patch image to a dimension (PS×T9) or more corresponding to the time T9 required from the switching start timing of the secondary transfer voltage until the secondary transfer voltage converges to V6.

As described above, in the conventional transfer voltage adjustment chart, the density of each patch image is changed discretely, and a plurality of patch images are formed with intervals. For this reason, if it is desired to finely adjust the density of each patch, the number of patches increases. In particular, in the case of using a machine with a high PS, it is necessary to secure a wide interval between each patch image, and there is a problem that the number of adjustment charts increases. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of suppressing an increase in the number of output test charts while increasing the level of a transfer voltage applied at the time of outputting a test chart for adjusting the transfer voltage. is to provide

An image forming apparatus of the present invention for solving the above problems includes an image carrier on which a toner image is formed;
a transfer member that transfers the toner image formed on the image carrier onto a recording material at a transfer portion;
a power source for applying a voltage to the transfer member; and control means capable of executing an output mode for outputting a predetermined test chart on which a test image is formed for adjusting the transfer voltage applied to the transfer member during image formation. wherein, in the output mode, the control means forms a predetermined test image continuous in the moving direction of the image carrier, and while the predetermined test image is passing through the transfer section, the power source a target value of the voltage applied by is switched a plurality of times to transfer the predetermined test image, and the test chart is formed with boundary lines for partitioning the predetermined test image into a plurality of mutually adjacent areas. It is characterized by

According to the present invention, an image forming apparatus capable of suppressing an increase in the number of output test charts while increasing the level of a transfer voltage applied when outputting a test image when outputting a test chart for transfer voltage adjustment. can provide

1 is a configuration diagram of an image forming apparatus according to an embodiment; FIG. 3 is a block diagram of a control circuit of the embodiment; FIG. FIG. 10 is a diagram showing the relationship between the secondary transfer voltage level and the patch image on the transfer voltage adjustment chart; 5 is a flow chart of transfer voltage adjustment in Embodiment 1. FIG. 5 is a diagram showing the relationship between the patch image of the transfer voltage adjustment chart and the secondary transfer voltage in Example 1. FIG. 4 is a test chart for transfer voltage adjustment in Example 1. FIG. 4 is a judgment result input screen for secondary transfer voltage adjustment in the first embodiment. FIG. 10 is a diagram showing the relationship between the patch image of the transfer voltage adjustment chart and the secondary transfer voltage in Example 2; 7 is a test chart for transfer voltage adjustment in Example 2. FIG. 2 is a conventional test chart for transfer voltage adjustment. FIG. 10 is a diagram showing the relationship between the pitch of a conventional patch image and the secondary transfer voltage; FIG. 10 is a diagram showing the relationship between a conventional secondary transfer voltage and a patch image;

[Example 1]
FIG. 1 is a schematic configuration diagram of an electrophotographic process image forming apparatus to which the present invention is applied. This image forming apparatus has four image forming units for yellow, magenta, cyan, and black. In the figure, a to d attached after the numerals in the reference numerals correspond to yellow, magenta, cyan, and black image forming portions, respectively. Therefore, in the following description, a to d will be omitted.

1 is a photoreceptor as an image carrier, 2 is a charger, 3 is an exposure device, 4 is a developing device, 41 is a developing sleeve in the developing device, 5 is a primary transfer roller, 6 is a photoreceptor cleaner, and 7 is an intermediate transfer. Belt 8 is an intermediate transfer belt cleaner.

9 is a secondary transfer roller, 10 is a fixing device, L is a laser beam for exposure, and P is a recording material such as paper or an OHP sheet.

When a CPU (not shown) that controls the entire image forming apparatus receives an image forming command for the recording material P, the photoreceptor 1, the intermediate transfer belt 7, the developing sleeve 41, the primary transfer roller 5, and the secondary as a transfer member. The rotation of the transfer roller 9 and the fixing device 10 is started. The photosensitive member 1 is driven by a drum motor (not shown). The surface of the photoreceptor 1 is uniformly charged by a charger 2 to which a high voltage is applied from a high voltage power source (not shown).

Next, the surface of the charged photoreceptor 1 rotates to reach the laser irradiation position from the exposure device 3 , and the exposure device 3 performs exposure according to image signals, forming an electrostatic latent image on the photoreceptor 1 . be done. After that, in the developing device 4 , a high voltage is applied to the developing sleeve 41 by a high voltage power source (not shown). Negatively charged toner is developed from the developing sleeve into a latent image with a positive potential (positive from the developing sleeve, negative with respect to GND), and rotates in the direction of the primary transfer roller 5 . The toner images on the four photoreceptors 1 are superimposed and transferred onto the intermediate transfer belt 7 by the primary transfer roller 5 at the primary transfer portion. Here, the intermediate transfer belt 7 functions as an image carrier that carries a toner image. Further, the toner image transferred onto the intermediate transfer belt 7 is transferred onto the recording material P by the secondary transfer roller 9 at the secondary transfer portion. A DC high voltage for transferring the toner image is also applied to the primary transfer roller 5 and the secondary transfer roller 9 from a high voltage power source (not shown). The transfer residual toner remaining on the photoreceptor 1 is scraped off and collected by the photoreceptor cleaner 6 . Untransferred toner remaining on the intermediate transfer belt 7 is scraped off and collected by an intermediate transfer belt cleaner 8 . The toner image transferred to the recording material P is fixed on the recording material P by a fixing device 10 under pressure and temperature, thereby obtaining a color image.

[Control block diagram]
FIG. 2 is a block diagram of the control circuit of the image forming apparatus of the present invention.

In FIG. 2, reference numeral 200 denotes a control device as control means for controlling the operation of the image forming apparatus, and the control device 200 includes a control circuit 201 including a CPU for controlling the operation of the image forming apparatus. The control device 200 also includes a storage unit 202 for storing programs, parameters, etc. for controlling the operation of the image forming apparatus, and a transfer voltage adjustment test pattern forming unit 203 for storing image data of a test chart for transfer voltage adjustment. and

As shown in FIG. 2, the control circuit 201 controls the image forming section 100 and sets the secondary transfer voltage applied to the secondary transfer roller 9 via the high voltage power supply circuit 204 to a desired value. configured to control.

Further, the control circuit 201 controls the operation of the image forming apparatus based on the input signal from the operation section 205, as shown in FIG.

In the transfer voltage adjustment mode by the user, which will be described later, the selection pattern information of the patch image that the user has determined to be optimum and selected can be input from the operation unit 205 . Pattern information of the patch image input from the operation unit 205 is stored in the storage unit 202 via the control circuit 201 . The secondary transfer voltage is adjusted during the image forming operation based on this stored information.

FIG. 3 shows the relationship between the secondary transfer voltage level and the patch image as the test image of the transfer voltage adjustment chart in this embodiment.

When the secondary transfer voltage is within the proper range, an appropriate amount of toner is evenly placed on the recording material. Otherwise, the amount of applied toner may become uneven, resulting in an image defect such as a transfer smear. If the secondary transfer voltage is too high, abnormal discharge occurs, resulting in image defects such as punch-through in which the amount of toner applied is partially reduced. The user selects the optimum patch image with a uniform amount of toner from the transfer voltage adjustment chart, and the secondary transfer voltage is adjusted to the optimum value, and the appropriate amount of toner is applied to the recording material without image defects. Images can be output.

[Method for Determining Secondary Transfer Voltage]
Next, a method for determining the secondary transfer voltage during image formation will be described.

A secondary transfer voltage for transferring a toner image onto a recording sheet is determined by an adjustment process called ATVC (Active Transfer Voltage Control).

ATVC is a process of adjusting the secondary transfer voltage according to the resistance value of the secondary transfer roller, which changes due to the ambient environment (temperature/humidity) and deterioration of the secondary transfer roller. It is executed by the control circuit 201 before the transfer process.

The ATVC applies a plurality of constant-voltage-controlled adjustment voltages from the high-voltage power supply circuit 204 to the secondary transfer roller 9, and when the adjustment voltages are applied, the secondary transfer portion is detected by current detection means (not shown). This is done by measuring the current that flows. ATVC allows the correlation between voltage and current to be calculated. Further, based on the calculated correlation between the current and the voltage, a voltage Vb for passing the secondary transfer setting current Itag required for secondary transfer is calculated.

The voltage (Vb+Vp) obtained by adding the recording material apportionment voltage Vp to Vb for flowing the secondary transfer target current Itag is the set voltage Vtr of the secondary transfer voltage under constant voltage control during the secondary transfer process following the adjustment process. is set as

[Transfer voltage adjustment mode]
Next, a procedure for adjusting the transfer voltage and a method for creating a test chart for adjusting the transfer voltage will be described.

4 is a flow chart for transfer voltage adjustment in the first embodiment, FIG. 5 is a diagram showing the relationship between the patch image of the transfer voltage adjustment chart in the first embodiment and the secondary transfer voltage, and FIG. 6 is the transfer voltage adjustment in the first embodiment. It is a test chart.

First, the user operates the operation unit 205 to start adjusting the secondary transfer voltage. That is, the control circuit 201 starts the output mode for outputting the transfer voltage adjustment test pattern based on the input signal from the operation unit 205 . (S401)

When the secondary transfer voltage adjustment is started, image forming data for generating a predetermined transfer voltage adjustment test chart composed of patch images as shown in FIG. 201. That is, the control circuit 201 acquires image forming data for generating a predetermined transfer voltage adjustment test chart from the transfer voltage adjustment test pattern forming unit 203 . (S402)

The control circuit 201 sends an image forming signal to each of the image forming section 100 and the high-voltage power supply circuit 204 according to the received image forming data. (S403)

The image forming section 100 includes the photoreceptor 1, the charger 2, the developing sleeve 41, the primary transfer roller 5, the secondary transfer roller 9, the exposure device 3, and the like. The image forming signal is a high voltage power source (not shown) that supplies a high voltage to each of the charging device 2, the developing sleeve 41, the primary transfer roller 5, and the secondary transfer roller 9, an output value control signal of the high voltage power source circuit 204, and an output value control signal of the exposure device 3. image signal and the like.

When the image forming signal is sent to the image forming section and the high-voltage power supply circuit 204, an image forming operation for forming a transfer voltage adjustment test chart on a recording material is started. (S404)
A patch image as a predetermined test image is formed continuously in the moving direction of the photoreceptor 1 .

A patch image formed on the surface of the photoreceptor 1 by the image forming unit 100 is transferred onto the intermediate transfer belt 7 by the primary transfer roller 5 . The patch image on the intermediate transfer belt 7 is transferred to the recording material P by applying a slope-shaped voltage, which will be described later, to the secondary transfer roller 9 from the high-voltage power supply circuit 204 . That is, the patch image 301 as a test image for adjusting the secondary transfer voltage is formed continuously in the movement direction of the photoreceptor 1, and voltages of different levels are applied to the secondary transfer when passing through the secondary transfer portion. It is applied to the roller 9 and transferred. That is, the control circuit 201 forms patch images 301 continuous in the moving direction of the photosensitive member 1 in the output mode. Then, when the patch image 301 passes through the secondary transfer portion, the control circuit 201 switches the target value of the voltage applied to the secondary transfer roller 9 multiple times to transfer the patch image 301 onto the recording material P. FIG.

The transferred patch image 301 is fixed on the recording material P by the pressure and temperature of the fixing device 10, and a transfer voltage adjustment test chart 300 as shown in FIG. 6 is output. (S405) As described above, in this embodiment, based on an instruction from the operation unit 205, an output mode for outputting a predetermined transfer voltage adjustment test chart can be executed.

A patch image 301 of the test chart 300 is a single-color solid image in which yellow (Y), magenta (M), cyan (C), and black (K) are arranged along the traveling direction of the recording material. The same pattern for each color is formed side by side so that the amount of toner applied on the intermediate transfer belt 7 is the same.

The numerical values shown on the left side of FIG. 6 indicate representative values of the level of the secondary transfer voltage applied to the secondary transfer roller, and the larger the numerical value, the higher the transfer voltage value. That is, when the patch image 301 passes through the secondary transfer portion, the control circuit 201 changes the target value of the voltage supplied by the high-voltage power supply circuit 204 multiple times to ramp up the voltage. That is, the control circuit 201 monotonously increases the target value of the voltage supplied by the high-voltage power supply circuit 204 when the patch image 301 passes through the secondary transfer portion. By changing the secondary transfer voltage applied to the secondary transfer roller in this manner, the state of the toner transferred onto the recording material is changed.

In this embodiment, the secondary transfer voltage level is prepared in 13 steps from -6 to +6, and the patch image selection pattern is divided into 13 steps, but the number of divisions can be changed.

Further, in this embodiment, when the secondary transfer voltage is switched in a slope manner to create a transfer voltage adjustment chart, a grid-like line image (boundary line) is formed as shown in FIG. This makes it easy for the user to select the patch image with the optimum toner coverage. The patch image 301 is partitioned into a plurality of areas adjacent to each other by the grid boundary lines. The patch image 301 is divided into a plurality of areas according to the transfer voltage level range. That is, in this embodiment, a line image (boundary line), which is an image for improving visibility, is also formed together with an image patch for confirming the toner application state.

In FIG. 6, line images (Y, M, and C are black and K is white (no toner is applied)) are formed to divide the patch image area.

Here, the relationship between the patch image of the transfer voltage adjustment chart and the secondary transfer voltage waveform will be described with reference to FIG.

In S404 described above, the secondary transfer voltage value supplied from the high-voltage power supply circuit 204 to the secondary transfer roller 9 is changed in a slope shape as shown in FIG. I am letting

The secondary transfer voltage applied to the secondary transfer roller 9 is determined by the result of the ATVC described above.

In this embodiment, the voltage Vtr1 obtained by adding the recording material apportionment voltage Vp to Vb calculated during ATVC is the central value (=3475 V) when the secondary transfer voltage level is 0 in FIG.

That is, the control circuit 201 controls the high-voltage power supply circuit 204 so that the secondary transfer roller 9 is applied with a voltage that varies in a slope from 2500 V to 4450 V centered on 3475 V from the leading edge to the trailing edge of the patch image 301 . do.

After the start of the transfer voltage adjustment, the initial voltage V1 for transfer voltage adjustment (2500 V in this embodiment) calculated based on the above-mentioned ATVC calculation result is applied to the secondary transfer roller by the timing when the leading edge of the patch image is transferred to the recording material. 9.

T1 is a time set as a time sufficient for the secondary transfer voltage to stabilize at the initial voltage V1 after the secondary transfer voltage starts to be supplied to the secondary transfer roller 9 .

When T1 elapses and the leading edge of the patch image is transferred to the recording material, the high-voltage power supply circuit 204 slopes the secondary transfer voltage level at a rate of ΔV2 (150 V in this embodiment) per area. increase likewise. That is, the secondary transfer voltage is increased in a slope during T2 from the leading edge position of the patch image to the trailing edge position.

In this embodiment, the secondary transfer voltage value applied to the secondary transfer roller 9 in the patch image area is increased in a slope form to 2500 to 2500V+150V×13=4450V. However, it is also possible to change the inclination of the slope by setting the change step value of the secondary transfer voltage to other than 150V.

The patch image is a solid image in which the toner application state changes according to the level of the secondary transfer voltage applied to the secondary transfer roller 9 from the leading edge of the image to the trailing edge of the image.

The user determined that the patch image for each color, which was divided into areas for each secondary transfer voltage level on the transfer voltage adjustment test chart output in this way, was optimal in terms of the toner application state without problems such as image defects or insufficient density. Select a patch image from the selection pattern.

In S406, confirmation is made as to whether or not the user has input the selected secondary transfer voltage level information from the operation unit 205 .

A secondary transfer voltage level selection screen as shown in FIG. 7 is displayed on the operation unit 205, and when information on the secondary transfer voltage level determined by the user to be the optimum value is input, the control circuit 201 selects it. Control to write the secondary transfer voltage level information to the storage unit 202 is executed. (S407)

When the secondary transfer voltage level information is written in the storage unit 202, the secondary transfer voltage adjustment ends. (S408)

After adjusting the secondary transfer voltage as described above, the secondary transfer voltage during the image generation operation is adjusted to a value calculated based on the secondary transfer voltage level information selected by the user. It is possible to obtain an image with toner on it.

As described above, in this embodiment, when preparing the test chart for adjusting the secondary transfer voltage, the secondary transfer voltage is changed in a slope to form the patch image.

As described above, in this embodiment, the secondary transfer voltage is changed in a slope when the test image is transferred. As a result, when the secondary transfer voltage is switched stepwise by a predetermined amount between patches as in the prior art, the patch interval required until the secondary transfer voltage stabilizes becomes unnecessary. This makes it possible to reduce the number of transfer voltage adjustment charts while increasing the transfer voltage level that can be formed per sheet of recording material.

[Example 2]
Another embodiment of the present invention will now be described.

The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the first embodiment. Accordingly, the same reference numerals are given to elements that are the same as or have functions equivalent to those of the image forming apparatus of the first embodiment, and detailed description thereof will be omitted, and the characteristic features of the present embodiment will be described.

In Example 1, the patch image of the test chart formed on the recording material was one in which the toner application state varied from the leading end of each color image to the trailing end of the image in accordance with the voltage applied to the secondary transfer roller 9. .

In this embodiment, a plurality of patch images of each color are provided, and spaces (without toner images) are provided to divide the plurality of patch images.

The number of intervals between each patch image is set such that the number of test charts does not increase.

According to the present embodiment, it is possible to improve the visibility of the chart when the user selects the patch image with the optimum toner-applied state, like the line image for dividing the patch image in FIG. 6 described above.

FIG. 8 is a diagram showing the relationship between the patch image of the transfer voltage adjustment chart and the secondary transfer voltage in the second embodiment, and FIG. 9 is the transfer voltage adjustment test chart of the second embodiment.

The patch image of the test chart 400 in FIG. 9 is a single-color solid image in which yellow (Y), magenta (M), cyan (C), and black (K) are arranged along the traveling direction of the recording material. The numerical value shown on the left side of the Y patch image in FIG. 9 indicates the level of the secondary transfer voltage applied to the secondary transfer roller. The amount of toner applied increases.

In this embodiment, the secondary transfer voltage level is prepared in 13 steps from -6 to +6, and the selection pattern of the toner coverage state of the patch image is divided into 13 steps. It is possible.

In the patch image of the test chart for adjusting the transfer voltage of Example 1, the toner borne state changes according to the level of the secondary transfer voltage applied to the secondary transfer roller 9 from the leading end of the image to the trailing end of the image as described above. It is one solid image.

On the other hand, the patch images of the test chart of Example 2 are provided with three patch images of each color, and two intervals (with no toner image) are provided for dividing the three patch images.

As in the first embodiment, 13 steps of secondary transfer voltage levels from -6 to +6 are prepared, and the patch image selection pattern is divided into 13 steps. The second embodiment differs from the first embodiment in that intervals are provided between the secondary transfer levels of -3 and -2 and between +2 and +3 to divide the image patches.

In this embodiment, the selection pattern of the secondary transfer voltage level is 13 steps, the number of patch images for each color is 3, and the number of patch intervals for each color is 2. Numerical values are also possible.

Further, in this embodiment, as in the case of the first embodiment, when creating a transfer voltage adjustment chart, as shown in FIG. An image is also formed together with an image patch for confirming the state of toner application.

In FIG. 9, line images (Y, M, and C are black and K is white (no toner is applied)) are formed to divide the patch image area.

Here, the relationship between the patch image of the transfer voltage adjustment chart and the secondary transfer voltage waveform in the second embodiment will be described with reference to FIG.

In the second embodiment, the secondary transfer voltage value supplied from the high-voltage power supply circuit 204 to the secondary transfer roller 9 is changed as shown in FIG. I am letting

After the transfer voltage adjustment is started, the initial voltage V3 for transfer voltage adjustment (2500 V in this embodiment) calculated based on the above-described ATVC calculation result is applied to the secondary transfer roller by the timing when the leading edge of the patch image is transferred to the recording material. 9.

T3 is a time period set as a time sufficient for the secondary transfer voltage to stabilize at the initial voltage V3 after the secondary transfer voltage starts to be supplied to the secondary transfer roller 9 .

After T3 has elapsed, the high-voltage power supply circuit 204 increases the secondary transfer voltage level by ΔV4 (150 V in this embodiment) per area during T4 from the leading edge position to the trailing edge position of the first patch image 401 on the recording material. The secondary transfer voltage is increased in a slope.

During T4, the secondary transfer voltage increases by 600V in a slope.

In the next period T5, the secondary transfer voltage is maintained at V3+ΔV4×4 (2500V+150V×4=3100V in this embodiment). No patch images are formed during this period, forming a gap between the next second patch image 402 .

Next, the high-voltage power supply circuit 204 applies the secondary transfer voltage at a rate of ΔV4 (150 V in this embodiment) per area of secondary transfer voltage level during T6 from the leading edge position to the trailing edge position of the second patch image 402. Increase in a slope.

During T6, the secondary transfer voltage ramps up by 750V.

In the next period T7, the secondary transfer voltage is maintained at V3+ΔV4×4+ΔV4×5 (2500 V+150 V×9=3850 V in this embodiment).

No patch image is formed during this period, forming a gap between the next third patch image 403 . Next, the high-voltage power supply circuit 204 increases the secondary transfer voltage at a rate of ΔV4 (150 V in this embodiment) per area of the secondary transfer voltage level from the leading edge position to the trailing edge position of the third patch image 403 in a slope shape. . During T8, the secondary transfer voltage rises in a slope of 600V.

In this embodiment, the secondary transfer voltage is ramped up to 2500V-2500V+150V×4=3100V in the first patch image area. Also, in the second patch image area, the secondary transfer voltage is ramped up to 3100V-3100V+150V×5=3850V. Also, the secondary transfer voltage is ramped up to 3850V-3850V+150V×4=4450V in the third patch image area. Each patch image is a solid image in which the toner-bearing state changes according to the level of the secondary transfer voltage applied to the secondary transfer roller 9 from the leading edge of the image to the trailing edge of the image.

The user selects a patch image with a secondary transfer voltage level that is determined to be optimal for each color without problems such as image defects or insufficient density from the output transfer voltage adjustment test chart.

After adjusting the secondary transfer voltage as described above, the secondary transfer voltage during the image generation operation is adjusted to a value calculated based on the secondary transfer voltage level information selected by the user. It is possible to obtain an image with toner on it.

As described above, in this embodiment, when preparing the test chart for adjusting the secondary transfer voltage, the secondary transfer voltage is changed in a slope to form the patch image. In addition, a plurality of patch images of each color are provided, and spaces (without toner images) are provided for dividing the plurality of patch images.

By setting the interval between each patch image to the number that does not increase the number of test charts, it is possible to increase the number of steps for each toner loading state that can be formed per sheet of recording material compared to the conventional method. It is possible to reduce the number of sheets.

Further, by providing an interval between the image patches, it is possible to improve the visibility of the chart when the user selects the patch image in the optimum toner-carrying state.

Others In this embodiment, an example in which the target value of the secondary transfer voltage applied when forming the patch image 301 is monotonically increased has been shown, but it may be monotonously decreased. Alternatively, the target value of the secondary transfer voltage may be maintained constant, or may be changed from an increase to a decrease.

In this embodiment, the high-voltage power supply circuit 204 as a power supply is controlled by constant voltage, but may be controlled by constant current. That is, the patch image 301 may be formed by monotonously increasing or decreasing the target value of the current supplied to the secondary transfer roller when forming the patch image 301 .

REFERENCE SIGNS LIST 1 photosensitive drum 100 image forming unit 201 control circuit 203 test pattern forming unit for adjusting transfer voltage 204 high-voltage power supply circuit

Claims (3)

an image carrier on which a toner image is formed;
a transfer member that transfers the toner image formed on the image carrier onto a recording material at a transfer portion;
a power supply that applies a voltage to the transfer member;
An image forming apparatus comprising: control means capable of executing an output mode for outputting a predetermined test chart on which a test image is formed for adjusting the transfer voltage applied to the transfer member during image formation,
The control means forms a predetermined test image continuous in the moving direction of the image carrier in the output mode, and the voltage applied by the power supply while the predetermined test image is passing through the transfer section. Switching the target value of a plurality of times to transfer the predetermined test image ,
The image forming apparatus according to claim 1, wherein the test chart is formed with boundary lines for partitioning the predetermined test image into a plurality of adjacent areas . 2. The control means ramps up the target value of the voltage applied by the power supply while the predetermined test image is passing through the transfer section in the output mode. image forming device. 3. The image forming apparatus according to claim 1 , wherein the boundary lines partition the predetermined test image in a grid pattern.

Images