JP2006178096A - Color image forming apparatus and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus capable of restricting wasteful consumption of transfer materials on which toner patches are formed for detecting image formation characteristics, and to provide its control method. <P>SOLUTION: A toner patch formed on the first transfer material is set to a first toner patch corresponding to the minimum size of the transfer material on which the color image forming apparatus can perform image formation, and thus a visible image is formed (S13). The size of the transfer material on which the visible image of the first toner patch thus formed is transferred is detected in the direction of its conveyance (S14). Based on the detected size in the direction of conveyance, a second toner patch formed on the following transfer material is determined (S18, S21, and S24). The second toner patch determined is formed on the following transfer material (S19, S23 and S25). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a color image forming apparatus that forms a toner patch on a transfer material, detects the chromaticity of the toner patch, and obtains image forming characteristics, and a control method thereof.

  In recent years, there has been a demand for higher image quality of printed images in color image forming apparatuses (printers) such as electrophotographic systems such as color printers and color copiers. However, in a color image forming apparatus, the characteristics of each part may fluctuate due to environmental changes or long-term use, and the density of a printed color image may fluctuate. In particular, in the case of an electrophotographic color image forming apparatus, even a slight environmental change may cause a change in the printed image density, and the color balance of the printed color image may be lost. Therefore, it is necessary to always have means for keeping the density of the image data and the relationship between the characteristics of the gradation of the printed image (density-gradation characteristics) constant.

  Therefore, for each color toner, gradation correction means such as a look-up table (LUT) storing process conditions such as several kinds of exposure amounts and development biases according to temperature and humidity is used, and temperature and humidity sensors are used. Based on the measured temperature and humidity, the process condition and the optimum value for gradation correction are selected and the image is printed. In addition, a toner patch for density detection is formed on an intermediate transfer member or drum with toner of each color so that a constant density-gradation characteristic can be obtained even if the characteristics of each part of the apparatus fluctuate. The density of the toner patch is detected by a density detection sensor for unfixed toner (hereinafter referred to as a density sensor), and the detection result is fed back to the process conditions such as exposure amount and development bias, and density control is performed to stabilize the patch. A print image is obtained.

  14A and 14B are diagrams illustrating an example of the configuration of the density sensor.

  The density sensor includes a light emitting element 51 such as an LED, a light receiving element 52 such as a photodiode and Cds, an optical element 53 used for coupling these light receiving and light emitting elements, an IC (not shown) that processes light reception data, and the like. It is comprised with the holder (not shown) which accommodates these.

  FIG. 14A shows a case in which both regular reflection components and irregular reflection components are detected, and FIG. 14B shows a configuration in which only irregular reflection components are detected without being affected by specular reflection.

  In the density control using this density sensor, the toner patch 54 is formed on the intermediate transfer belt 55 or the photosensitive drum and the density is detected, and then the transfer to the transfer material (recording sheet) is performed. In addition, changes in image color balance due to fixing are not controlled. Therefore, after transferring and fixing, the density of the single-color toner image on the transfer material or the chromaticity of the full-color image is detected, and feedback is given to the process conditions such as exposure amount, process conditions, look-up table (LUT), etc. A color image forming apparatus that controls density or color matching of a formed image after fixing is also considered (see Patent Document 1). The configuration of the density sensor and the color sensor in Patent Document 1 is the same as the configuration of the density sensor in FIG.

  Next, FIG. 15 is a diagram showing an example of a toner patch pattern for controlling density or color matching of an image formed on a transfer material.

The toner patch pattern 1301 is formed by continuously forming C, M, Y, K single color or mixed color toner patches while changing the density or chromaticity.
JP 2003-84532 A

  However, the above control method has the following problems.

  First, in order to obtain a stable image, toner patches of various chromaticities are formed on the transfer material, and these chromaticities are actually measured with a color sensor to determine the difference from the desired chromaticity and fed back to the process conditions. It is necessary to apply. At this time, the number of toner patches that can be formed on the transfer material is limited by the transfer speed of the transfer material and the measurement time per toner patch by the color sensor. Therefore, when the length of the transfer material used in the conveyance direction is short with respect to the number of toner patches necessary for calculating the chromaticity, the toner patch pattern is divided into two or three groups and transferred. It is necessary to form on the material. In that case, it is desirable to designate the size of the transfer material to be used in advance and form a toner patch pattern suitable for the size.

  However, if the length of the transfer material to be used in the transport direction is unknown, it is impossible to form a toner patch according to the size of the transfer material. Alternatively, the number of divisions of the toner patch pattern is maximized so that the toner patch is surely formed on the transfer material even when the transfer material having the minimum size is conveyed. In this way, a plurality of transfer materials are always required regardless of the size (long or short) of the size of the transfer material that is actually conveyed, so that the transfer material is wasted.

  The present invention has been made in view of the above problems, and the present invention is characterized in that a color image forming apparatus capable of suppressing wasteful consumption of a transfer material for forming a toner patch for detecting image forming characteristics, and It is to provide a control method.

A color image forming apparatus according to an aspect of the present invention has the following configuration. That is,
A transfer unit that transfers a visible image formed according to an image signal to a transfer material, and a density or chromaticity of a predetermined toner patch formed on the transfer material by the transfer unit is detected by a color sensor. A color image forming apparatus having image forming characteristic detecting means for detecting a forming characteristic,
A toner patch formed on the first transfer material is set to a first toner patch corresponding to the minimum size of the transfer material that can be imaged by the color image forming apparatus, and a visible image of the first toner patch is transferred to the transfer unit. First patch formation control means for forming
Detecting means for detecting a transfer direction size of the transfer material onto which a visible image of the first toner patch formed by the first patch formation control means is transferred;
Determining means for determining a second toner patch to be formed on a subsequent transfer material based on the transport direction size detected by the detecting means;
And second patch formation control means for forming the second toner patch determined by the determination means on a subsequent transfer material.

A color image forming apparatus according to an aspect of the present invention has the following configuration. That is,
A transfer unit that transfers a visible image formed according to an image signal to a transfer material, and a density or chromaticity of a predetermined toner patch formed on the transfer material by the transfer unit is detected by a color sensor. A color image forming apparatus having image forming characteristic detecting means for detecting a forming characteristic,
First patch formation control means for setting a toner patch to be formed on the first transfer material to a required maximum amount and forming a visible image of the first toner patch on the transfer means;
Detection means for detecting a transfer direction size of the transfer material to which a visible image of the first toner patch formed by the first patch formation control means is to be transferred;
An acquisition means for acquiring a toner patch amount actually transferred and formed on the first transfer material based on the transport direction size detected by the detection means;
Control means for controlling detection of the image formation characteristics by the image formation characteristic detection means in accordance with the toner patch amount acquired by the acquisition means;
A determining unit that determines a second toner patch to be formed on a subsequent transfer material based on the toner patch amount acquired by the acquiring unit and a transfer direction size of the transfer material detected by the detecting unit;
And second patch formation control means for forming the second toner patch determined by the determination means on a subsequent transfer material.

A color image forming apparatus according to an aspect of the present invention has the following configuration. That is,
A transfer unit that transfers a visible image formed according to an image signal to a transfer material, and a density or chromaticity of a predetermined toner patch formed on the transfer material by the transfer unit is detected by a color sensor. A color image forming apparatus having image forming characteristic detecting means for detecting a forming characteristic,
Detection means for detecting the transfer material size in the transfer direction;
First determination means for determining a first toner patch to be formed on the transfer material in accordance with the transfer direction size of the transfer material detected by the detection means;
First patch formation control means for forming the first toner patch determined by the first determination means on the transfer material by the transfer means;
Second determination means for determining a second toner patch to be formed on a subsequent transfer material based on the first toner patch formed on the transfer material and the transport direction size detected by the detection means;
And second patch formation control means for forming the second toner patch determined by the second determination means on a subsequent transfer material.

A control method in a color image forming apparatus according to an aspect of the present invention includes the following steps. That is,
A transfer unit that transfers a visible image formed according to an image signal to a transfer material, and a density or chromaticity of a predetermined toner patch formed on the transfer material by the transfer unit is detected by a color sensor. A control method in a color image forming apparatus having image forming characteristic detecting means for detecting a forming characteristic,
A toner patch formed on the first transfer material is set to a first toner patch corresponding to the minimum size of the transfer material that can be imaged by the color image forming apparatus, and a visible image of the first toner patch is transferred to the transfer unit. A first patch formation control step for forming
A detection step of detecting a conveyance direction size of the transfer material onto which a visible image of the first toner patch formed in the first patch formation control step is transferred;
A determination step of determining a second toner patch to be formed on a subsequent transfer material based on the transport direction size detected in the detection step;
A second patch formation control step of forming the second toner patch determined in the determination step on a subsequent transfer material.

A control method in a color image forming apparatus according to an aspect of the present invention includes the following steps. That is,
A transfer unit that transfers a visible image formed according to an image signal to a transfer material, and a density or chromaticity of a predetermined toner patch formed on the transfer material by the transfer unit is detected by a color sensor. A control method in a color image forming apparatus having image forming characteristic detecting means for detecting a forming characteristic,
A first patch formation control step of setting a toner patch to be formed on the first transfer material to a necessary maximum amount and forming a visible image of the first toner patch on the transfer means;
A detection step of detecting a transfer direction size of the transfer material to which a visible image of the first toner patch formed in the first patch formation control step is to be transferred;
An acquisition step of acquiring a toner patch amount actually transferred and formed on the first transfer material based on the transport direction size detected in the detection step;
A control step of controlling the detection of the image formation characteristics by the image formation characteristic detection means according to the toner patch amount acquired in the acquisition step;
A determination step of determining a second toner patch to be formed on a subsequent transfer material based on the toner patch amount acquired in the acquisition step and a conveyance direction size of the transfer material detected in the detection step;
A second patch formation control step of forming the second toner patch determined in the determination step on a subsequent transfer material.

A control method in a color image forming apparatus according to an aspect of the present invention includes the following steps. That is,
A transfer unit that transfers a visible image formed according to an image signal to a transfer material, and a density or chromaticity of a predetermined toner patch formed on the transfer material by the transfer unit is detected by a color sensor. A control method in a color image forming apparatus having image forming characteristic detecting means for detecting a forming characteristic,
A detection process for detecting the transfer material size in the transfer direction;
A first determination step of determining a first toner patch to be formed on the transfer material according to the transport direction size of the transfer material detected in the detection step;
A first patch formation control step of forming the first toner patch determined in the first determination step on the transfer material by the transfer unit;
A second determination step of determining a second toner patch to be formed on a subsequent transfer material based on the first toner patch formed on the transfer material and the transport direction size detected in the detection step;
And a second patch formation control step of forming the second toner patch determined in the second determination step on a subsequent transfer material.

  According to the present invention, there is an effect that wasteful consumption of a transfer material for forming a toner patch for detecting image forming characteristics can be suppressed.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a structural cross-sectional view mainly showing a printer engine (image forming unit) of a color laser beam printer which is an example of a color image forming apparatus according to an embodiment of the present invention.

  The image forming unit of this color laser beam printer has image forming units for four colors of yellow (yellow), magenta (M), cyan (C), and black (K). An electrostatic latent image is formed by exposure based on image data of the color to be developed, and the electrostatic latent image is developed to be a visible image, and then the color visible image is transferred to a transfer material (recording sheet) that is a recording medium. The final printed image is obtained. That is, the image forming unit includes a photosensitive drum (5Y, 5M, 5C, 5K), a charger (7Y, 7M, 7C, 7K), a laser scanner for each station arranged in parallel for the number of development colors (here, four colors). (10Y, 10M, 10C, 10K), developing device (8Y, 8M, 8C, 8K), toner cartridge (11Y, 11M, 11C, 11K), intermediate transfer belt 12, primary transfer roller (6Y, 6M, 6C, 6K) ), A secondary transfer roller 9, a paper feeding / conveying unit, a fixing device 13, and the like.

  The photosensitive drums (5Y, 5M, 5C, 5K) are configured by applying an organic optical conductive layer to the outer periphery of an aluminum cylinder, and are rotationally driven in a counterclockwise direction by a drive motor (not shown). The chargers (7Y, 7M, 7C, and 7K) include charging sleeves (7YS, 7MS, 7CS, and 7KS) for primarily charging the photosensitive drums (5Y, 5M, 5C, and 5K). The respective surfaces of the photosensitive drums (5Y, 5M, 5C, 5K) are selectively exposed based on the input image data by the corresponding laser scanners (10Y, 10M, 10C, 10K), and sequentially electrostatically A latent image is formed. The developing devices (8Y, 8M, 8C, 8K) are provided with developing sleeves (8YS, 8MS, 8CS, 8CK) in order to visualize the electrostatic latent image.

  The intermediate transfer belt 12 is an endless belt stretched by a driving roller 18a and driven rollers (18b, 18c), and rotates clockwise while contacting the photosensitive drum (5Y, 5M, 5C, 5K). The toner images of the respective colors on the photosensitive drums (5Y, 5M, 5C, 5K) are sequentially primary-transferred onto the belt surface by the primary transfer rollers (6Y, 6M, 6C, 6K). As a result, a primary transfer image in which a plurality of color toners are superimposed is formed on the intermediate transfer belt 12.

  A transfer material 1 is accommodated in a paper feed cassette 2 or a paper feed tray 3 as a paper feed unit, and this transfer material 1 is transported on a transport path 25 including a paper feed roller 4 and a transport roller 24. Then, the position reaches the pre-registration sensor 19 position. Thereafter, the transfer material 1 is further conveyed by a certain amount, reaches the registration roller 23, forms a loop, and waits.

  Next, the transfer material 1 that has been waiting is transported again and sent to the position of the secondary transfer roller 9. Here, the secondary transfer roller 9 abuts on the intermediate transfer belt 12, and the transfer material 1 is nipped and conveyed by the intermediate transfer belt 12 and the secondary transfer roller 9, whereby multiple transfer is performed on the intermediate transfer belt 12. The color visible images are secondarily transferred to the transfer material 1 at once. The secondary transfer roller 9 is in contact with the intermediate transfer belt 12 as indicated by a solid line during the secondary transfer, but is separated to a position indicated by a dotted line after the secondary transfer. The cleaner container 21 cleans the intermediate transfer belt 12 with a built-in cleaning blade, and stores the toner remaining on the intermediate transfer belt 12 without being secondarily transferred to the transfer material 1 by the secondary transfer roller 9 as waste toner. . The fixing device 13 is for fixing the toner image on the transfer material 1 to the transfer material 1 while conveying the transfer material 1, and for fixing the transfer material 1 to the fixing roller 14 in pressure contact with the fixing roller 14 for heating the toner. The pressure roller 15 is provided. The fixing roller 14 and the pressure roller 15 are formed in a hollow shape, and heaters 16 and 17 are incorporated therein, respectively. After the toner is fixed in this manner, the transfer material 1 is conveyed by the paper discharge roller 26 and discharged to the paper discharge unit 27, and the image forming operation is completed.

  In FIG. 1, the color sensor 42 is disposed downstream of the fixing device 13 in the conveyance path of the transfer material 1. The color detection unit of the color sensor 42 is directed to the image forming surface of the transfer material 1 being conveyed, and detects the RGB value of the patch after fixing formed on the transfer material 1.

  The chromaticity control according to the first to third embodiments is performed by the user's manual operation when the user desires to perform the control, or when the environmental change is detected, or after the chromaticity control is executed. It is automatically performed at a predetermined timing such as the number of sheets set.

[Embodiment 1]
In the first embodiment, when the length of the transfer material 1 used for chromaticity control in the transport direction is unknown, the toner patch is formed with the size of the toner patch formed on the first transfer material 1 as the minimum size. When the toner patch is transferred to the first transfer material, the length of the transfer material 1 in the transport direction is measured, and the transfer material 1 is formed on the second and subsequent transfer materials 1 based on the measurement result. Determine the toner patch pattern. As a result, a toner patch corresponding to the size of the transfer material 1 is formed on the second and subsequent transfer materials 1, and chromaticity control is executed.

  FIG. 2 is a block diagram illustrating the configuration of the color image forming apparatus (color printer) according to the present embodiment.

  In FIG. 2, a control unit 201 controls the overall operation of the color image forming apparatus. An image forming unit 202 includes, for example, an image forming unit as shown in FIG. The laser drive circuit 204 inputs image signals corresponding to the image signals of the respective colors from the control unit 201, drives the semiconductor lasers corresponding to the respective colors, and operates on the corresponding photosensitive drums (5Y, 5M, 5C, 5K). Then, an electrostatic latent image corresponding to the image signal is formed. The transport motor 205 is a motor for driving the transfer material 1, and by rotating the motor 205, the transfer material is transported from the paper feed cassette and transported on the transport path 25. The motor driver 203 rotationally drives the transport motor 205 in accordance with a drive signal from the control unit 201. In FIG. 2, the other photosensitive drums (5Y, 5M, 5C, and 5K), the intermediate transfer belt 12, and the rotation driving motor for the fixing unit 13 are omitted.

  The control unit 201 includes a CPU 210, a ROM 211 that stores a control program executed by the CPU 210, and a RAM 212 that is used as a work area for temporarily storing various data during the control operation by the CPU 210. The timer 213 is used to count a predetermined time under the control of the CPU 210, or to count the time from when an event is issued until the next event occurs. The time from when the leading edge of the transfer material 1 is detected by the sensor 19 until the trailing edge is detected is counted.

  FIG. 3 is a flowchart for explaining a process for measuring the length in the conveyance direction of the transfer material 1 using the pre-registration sensor 19 in the color image forming apparatus according to the present embodiment. A program for executing this process is stored in the ROM 211. This process is executed under the control of the CPU 210.

  4A to 4C are diagrams for explaining the transport state of the transfer material 1 when measuring the length in the transport direction of the transfer material 1 according to the flowchart of FIG.

  First, in step S1, a loop is formed at the position of the registration roller 23 on the conveyance path 25, and the timing for resuming conveyance of the transfer material 1 (FIG. 4A) that is on standby is awaited. This timing is a timing at which a toner image of each color is formed on the intermediate transfer belt 12 and the image is transferred to the transfer material 1. When it is time to resume the transfer of the transfer material 1, in step S2, the transfer motor 205 is rotationally driven to start the transfer of the transfer material 1. In step S3, the timer 213 starts counting in accordance with the resumption of the conveyance. After the transfer material 1 is thus conveyed on the conveyance path 25 (FIG. 4B), it waits for the pre-registration sensor 19 to detect the rear end of the transfer material 1 in step S4. When the trailing edge of the transfer material 1 is thus detected by the pre-registration sensor 19 (FIG. 4C), the counting operation by the timer 213 is stopped in step S5. In step S6, the loop length when the transfer material 1 is looped in the state shown in FIG. 4A, the distance from the pre-registration sensor 19 to the registration roller 23, the time measured by the timer 213, and the transfer material 1 The length in the conveyance direction of the conveyed transfer material 1 is calculated from the conveyance speed.

  FIGS. 5A to 5C are diagrams illustrating an example in which a toner patch used in chromaticity control according to the first embodiment is formed on a transfer material.

  In the first embodiment, the number of toner patches necessary for chromaticity control is eight tp1 to tp8. In the first embodiment, since the length of the first transfer material 1 in the conveyance direction is unknown, the first transfer material 401 has toner patches tp1 to tp3 as shown in FIG. The toner patches tp1 to tp3 are printed using the toner patch pattern 402. Since the size of the toner patch pattern 402 is shorter than the length of the smallest transfer material that can be printed by the color image forming apparatus according to the present embodiment, the toner patch pattern 402 can be reliably formed on the transfer material 401.

  Next, in the second transfer material 403, the length in the transport direction of the second transfer material can be predicted based on the length of the first transfer material. If it is determined that the toner patches tp4 to tp8 can be formed on the second transfer material 403, the toner patches are formed using the toner patch pattern 404 as shown in FIG. On the other hand, if it is determined that all the toner patches tp4 to tp8 cannot be formed on the second transfer material 403, the toner patch pattern 406 (tp4 to tp6) is applied to the second transfer material 405 as shown in FIG. ) And a toner patch pattern 408 (tp7 to tp8) is used for the third transfer material 407.

  That is, in the first embodiment, a minimum toner patch is formed on the first transfer material, and when the length of the transfer material in the transport direction is determined, the transfer material in the transport direction of the second and subsequent transfer materials is determined. It is determined that the length is the same, and the toner patches to be formed on the second and subsequent transfer materials are determined based on the remaining toner patches and the size of the transfer material.

  FIG. 6 is a flowchart illustrating chromaticity detection processing using the color sensor 42 when the length of the transfer material 1 in the conveyance direction is unknown in the color image forming apparatus according to the first embodiment.

  When executing chromaticity control, first, in step S11, since the length of the transfer material 1 in the conveyance direction is unknown, the toner patch pattern 402 (FIG. 5A) is selected. Next, when conveyance of the transfer material 1 is started in step S12, the transfer material 1 is conveyed from the paper feed cassette 2 or the paper feed tray 3 to the secondary transfer roller 9, and is formed on the intermediate transfer belt 12 in step S13. The toner patch image is transferred to the transfer material 1. At this time, in parallel with the above processing, in step S14, the length of the transfer material 1 in the transport direction is measured by the method described in FIG. Thereafter, in step S15, the transfer material 1 onto which the toner patch has been transferred is conveyed to the fixing device 13 and is passed through the fixing device 13, whereby the toner patch is melted and fixed on the transfer material 1. After the toner image is fixed in this manner, the transfer material 1 is conveyed by the paper discharge roller 26, and the color sensor 42 detects the chromaticity of the toner patch on the transfer material 1 in step S16.

  When the detection of the toner patch on the first transfer material 1 is thus completed, the transfer material 1 is discharged to the paper discharge tray 27. In step S17, the length in the conveyance direction of the transfer material 1 measured in step S14 is compared with the size of the remaining toner patch pattern 404 (FIG. 5B). If the length of the transfer material 1 in the transport direction is longer, the process proceeds to step S18, and the toner patch pattern 404 is selected. Next, in step S19, the toner patch pattern 404 is formed on the transfer material 1 in the same manner as the first sheet. Next, in step S20, the toner patch formed on the second transfer material 1 by the color sensor 42. Detect chromaticity of.

  On the other hand, if the length of the transfer material 1 in the transport direction is shorter in step S17, the process proceeds to step S21, and the toner patch pattern 406 is selected for the second transfer material to create a toner patch (step S22). In step S23, the color sensor 42 detects the chromaticity of the toner patch. In step S24, a toner patch pattern 408 is selected on the third transfer material 1, and in step S25, a toner patch pattern is formed. In step S26, the chromaticity of the toner patch is detected.

  When detection of all toner patches (tp1 to tp8) necessary for chromaticity control is completed in this way, the obtained chromaticity information is fed back to image forming conditions such as exposure amount, development bias, and lookup table (LUT). Thus, a stable image can be obtained.

  As described above, according to the first embodiment, when the color patch is printed on the transfer material 1 and the color is read to change the image forming characteristics, the length of the transfer material to be used in the conveyance direction is unknown. Even in this case, a minimum toner patch is formed on the first transfer material, and the length of the transfer material in the transport direction is measured. A toner patch pattern having a size suitable for the length in the direction can be formed. Therefore, useless transfer material consumption can be suppressed and usability can be improved.

[Embodiment 2]
In the first embodiment, when the length of the transfer material 1 used for chromaticity control in the transport direction is unknown, only a part of the toner patch required for chromaticity control is formed on the first transfer material. It was something to do. Therefore, at least two transfer materials are required to form all the toner patches necessary for chromaticity control.

  On the other hand, in the second embodiment, in the color image forming apparatus of FIG. 1, when the length in the transport direction of the transfer material 1 used for chromaticity control is unknown, the chromaticity is applied to the first transfer material. All the toner patches necessary for control are formed, and the length of the transfer material 1 in the conveyance direction is measured by the pre-registration sensor 19, and all the toner patches are formed on the first transfer material 1. A method for selecting a toner patch pattern to be formed on the second transfer material 1 based on the measured length of the transfer material 1 in the conveyance direction only when it cannot be described.

  7A and 7B are diagrams illustrating an example in which a toner patch pattern used in chromaticity control according to the second embodiment is formed on a transfer material.

  Also in the second embodiment, as in the first embodiment, eight toner patches tp1 to tp8 are necessary for chromaticity control, and the length of the transfer material 1 in the conveyance direction is unknown, FIG. As shown in (A), the first transfer material 601 has an intermediate so as to form a toner patch using a toner patch pattern 602 composed of all the toner patches tp1 to tp8 necessary for obtaining image forming characteristics. A toner patch is formed on the transfer belt 12. If the length of the first transfer material 601 is short and all of the eight toner patches tp1 to tp8 cannot be formed on the transfer material 601, the second sheet as shown in FIG. 7B. The transfer material 603 is used, and the toner patch pattern 604 is used for the transfer material 603 to form the remaining toner patches.

  FIG. 8 shows the formation of a toner patch on the transfer material 1 and the chromaticity by the color sensor 42 when the length of the transfer material 1 in the transport direction is unknown in the color image forming apparatus according to Embodiment 2 of the present invention. In the flowchart explaining the detection process, a program for executing this process is stored in the ROM 211 and executed under the control of the CPU 210. The hardware configuration of the color image forming apparatus according to the second embodiment is the same as the hardware configuration of the color image forming apparatus according to the above-described first embodiment, and thus the description thereof is omitted.

  In the second embodiment, when the chromaticity control is executed, since the length of the first transfer material 1 in the transport direction is unknown, the toner patch pattern 602 (FIG. 7A) shown in FIG. tp1 to tp8) are selected. In step S 32, when the conveyance motor 205 starts to rotate and the transfer material 1 starts to be conveyed, the transfer material 1 is conveyed from the paper feed cassette 2 or the paper feed tray 3 to the secondary transfer roller 9. Accordingly, the toner patch image formed on the intermediate transfer belt 12 is transferred to the transfer material 1 in step S33. At this time, in parallel with the above processing, the length of the transfer material 1 in the transport direction is measured in step S34 by the same method as in the first embodiment. Based on the measurement result and the length of the toner patch in the transport direction, the number of toner patches detected by the color sensor 42 is calculated in step S35.

  For example, when the measured length of the transfer material 1 in the transport direction is the size of the transfer material 601 in FIG. 7A, the toner patches formed on the transfer material 601 are four toner particles tp1 to tp4. The subsequent toner patches tp5 to tp8 are not transferred onto the transfer material 601. In this case, the number of toner patches of the first transfer material 601 detected by the color sensor 42 is four. At this time, the toner images of the remaining toner patches tp5 to tp8 formed on the intermediate transfer belt 12 are removed by the cleaner container 21 and stored as waste toner.

  The first transfer material 1 onto which the toner patch has been transferred is conveyed to the fixing device 13 and passes through the fixing device 13, whereby the toner patch is melted and fixed on the transfer material 1 (step S36). Further, the transfer material 1 is further conveyed by the paper discharge roller 26, and the chromaticity of the toner patch is detected by the color sensor 42 in step S37. At this time, the chromaticities of the toner patches of the number determined in step S35 are detected. When all the toner patches on the first transfer material 1 are thus detected, the transfer material 1 is discharged to the paper discharge tray 27.

  Next, in step S38, the length of the first transfer material 1 in the transport direction measured in step S34 is compared with the size of all toner patch patterns 602, and whether or not to end chromaticity control, that is, one It is determined whether all the toner patch patterns 602 have been transferred to the first transfer material 1 and the chromaticity of all the toner patches has been detected. When the length of the first transfer material 1 in the transport direction is sufficiently long, all toner patches necessary for chromaticity control are formed on the first transfer material, and the chromaticity detection by the color sensor 42 is performed. It is determined that the process is finished, and the chromaticity control is finished at this point.

  On the other hand, if the length of the first transfer material 1 in the transport direction is short, it is determined that all the toner patches necessary for chromaticity control have not been transferred to the first transfer material 1. Proceeding to S39, chromaticity control is continued. In this example, for example, the toner patch pattern 604 is selected as the toner patch pattern to be formed on the second transfer material 1, and the toner patch pattern 604 is selected as in the case of the first transfer material 1. A patch pattern 604 is formed on the transfer material (step S40), and the chromaticity of the toner patch is detected by the color sensor 42 (step S41). When the chromaticity of all toner patches necessary for chromaticity control is thus detected, the chromaticity control is terminated.

  A stable image can be obtained by feeding back the chromaticity information thus obtained to image forming conditions such as an exposure amount, a developing bias, and a look-up table (LUT).

  As described above, according to the second embodiment, the toner patch is formed on the first transfer material even when the length of the transfer material used in the chromaticity control execution is unknown. In addition, by measuring the length of the transfer material in the transport direction, a toner patch pattern having a size suitable for the length of the transfer material in the transport direction can be formed on the second and subsequent sheets.

  Furthermore, when the toner patch is formed on the first transfer material, all the toner patches necessary for chromaticity control are formed on the intermediate transfer belt and transferred to the transfer material. Only when all the toner patches necessary for controlling the chromaticity cannot be transferred to the material, the second and subsequent transfer materials are used to form a toner patch pattern. Therefore, if the number of transfer materials necessary for this chromaticity control is sufficiently large, the number of transfer materials to be used can be reduced and the usability can be improved as compared with the first embodiment. it can.

[Embodiment 3]
In the first and second embodiments, when the size of the transfer material is unknown when the chromaticity control is executed, a toner patch pattern is formed on the first transfer material, and the pre-registration sensor 19 detects the transfer material 1. The method for measuring the length in the transport direction and determining the toner patch size for the second and subsequent sheets based on the measurement result has been described.

  In contrast, in the third embodiment, when the length of the transfer material 1 in the transport direction is unknown in the color image forming apparatus having the double-sided printing mechanism, first, only the length of the transfer material 1 in the transport direction is measured. After that, the transfer material 1 is conveyed to the double-sided conveyance path using the double-sided printing mechanism, and the number of toner patches corresponding to the length of the transfer material 1 is formed on the back surface of the transfer material 1. .

  FIG. 9 is a structural cross-sectional view showing the configuration of the image forming unit of the color image forming apparatus according to Embodiment 3 of the present invention. The same parts as those in FIG. .

  Here, a double-sided conveyance roller 31 is provided on the double-sided flapper 28, the switchback mechanism 29, and the double-sided conveyance path 30 in order to enable image formation on both sides of the transfer material 1.

  With reference to FIGS. 10A and 10B and FIGS. 11A to 11C, a double-sided printing operation in the color image forming apparatus according to the third embodiment will be described.

  When performing the double-sided printing operation, first, similarly to the above-described first embodiment, the transfer material 1 is fed from the paper feed cassette 2 or the paper feed tray 3, and the surface of the transfer material 1 is transferred by the secondary transfer roller 9. The toner image is transferred from the intermediate transfer belt 12. The toner image is melted and fixed on the transfer material 1 by the fixing unit 13 (FIG. 10A).

  Thereafter, the transfer material 1 is transported to the switchback mechanism 29 by the double-sided flapper 28 (FIG. 10B), where the transporting direction of the transfer material 1 is changed and transported to the double-sided transport path 30 by the double-sided transport roller 31. (FIG. 11 (A)). Then, the transfer material 1 conveyed from the double-sided conveyance path 30 passes through the conveyance path 25 again, and the toner image is again transferred to the back surface thereof by the secondary transfer roller 9, and the toner image is melted and fixed by the fixing unit 13. (FIG. 11B). Thereafter, the paper is discharged to the paper discharge tray 27 by the double-sided flapper 28, and the double-sided printing operation is finished (FIG. 11C). Since such double-sided printing is a well-known technique, only a brief description will be given.

  FIGS. 12A and 12B are diagrams for explaining an example of printing a toner patch on a transfer material in the color image forming apparatus according to Embodiment 3 of the present invention.

  In the third embodiment, eight toner patches tp1 to tp8 are used for chromaticity control as in the first and second embodiments, and all eight toner patches are formed on one transfer material 1001. If possible, as shown in FIG. 12A, all eight toner patches are formed on one transfer material by using a toner patch pattern 1002 composed of all toner patches.

  On the other hand, when all eight toner patches tp1 to tp8 cannot be formed on one transfer material, as shown in FIG. 12B, a toner patch made up of toner patches tp1 to tp4 on the first transfer material 1003. Using the pattern 1004, a toner patch is formed on the second transfer material 1005 using a toner patch pattern 1006 composed of toner patches tp5 to tp8. In this case, if all the eight toner patches tp1 to tp8 cannot be formed even if the second transfer material is used, it is a matter of course that more transfer materials are used.

  FIG. 13 is a flowchart for explaining toner patch formation on a transfer material and chromaticity detection processing by the color color sensor 42 in the color image forming apparatus according to Embodiment 3 of the present invention. A program for executing this processing is a ROM 211. And is executed under the control of the CPU 210. The hardware configuration of the color image forming apparatus according to the third embodiment is the same as the hardware configuration of the color image forming apparatus according to the above-described first embodiment, and thus the description thereof is omitted.

  In the third embodiment, when the paper size is unknown at the time of executing the chromaticity control, first, in step S51, the toner patch pattern is not formed, and the transfer material 1 is transferred from the paper feed cassette 2 or the paper feed tray 3. In step S52, the pre-registration sensor 19 is used to measure the length of the transfer material 1 in the conveyance direction. The length of the transfer material 1 in the conveyance direction is measured by the same method as in the first embodiment. After the length is measured in this way, the transfer material 1 passes through the fixing unit 13 and is conveyed by the double-sided flapper 28 to the double-sided conveyance path 30 by the double-sided conveyance roller 31 via the switchback mechanism unit 29 (step S53). 10 to 11 (A)).

  In step S54, the length of the transfer material 1 in the conveyance direction measured in step S52 is compared with the length of the toner patch pattern 1002, and necessary for chromaticity control, that is, all these toner patches are formed. The number of transfer materials 1 necessary for the transfer and the toner patch pattern to be formed on each transfer material 1 are determined.

  Here, when the length of the transfer material 1 in the transport direction is long and all the toner patches required for chromaticity control can be formed on the first transfer material, the process proceeds to step S62, and all the toner patches tp1 to tp8 are formed. A toner patch pattern 1002 is selected. In step S63, conveyance of the transfer material 1 is started from the duplex conveyance path 30, and in step S64, a toner patch pattern 1002 is formed and fixed on the back surface of the conveyed transfer material 1. In step S65, the chromaticity of the toner patch is detected by the color sensor 42, and the chromaticity control is terminated.

  On the other hand, when the length of the transfer material 1 in the transport direction is short and all the toner patches tp1 to tp8 cannot be formed on one transfer material 1 (when the second or subsequent transfer material 1 is required). Proceeding to step S55, toner patch patterns 1004 and 1006 are selected in the example of FIG. Next, in step S56, the transfer material 1 is conveyed from the double-sided conveyance path 30, and in step S57, a toner patch pattern 1004 is formed on the back surface of the transfer material 1. The chromaticity of the toner patch is detected (step S58).

  For the second transfer material 1, in step S59, feeding of the transfer material 1 from the paper feed cassette 2 or the paper feed tray 3 is started, and in step S60, the remaining toner is applied to the surface of the transfer material. A patch pattern 1006 is formed, and the chromaticity of the toner patch is detected by the color sensor 42 in step S61 in the same manner as described above. When the detection of all toner patches necessary for chromaticity control is thus completed, the chromaticity control is terminated. A stable image can be obtained by feeding back the chromaticity information thus obtained to image forming conditions such as an exposure amount, a developing bias, and a look-up table (LUT).

  As described above, according to the third embodiment, when the length of the transfer material in the conveyance direction is unknown at the time of executing the chromaticity control, the length of the transfer material in the conveyance direction is first determined by the pre-registration sensor 19. After measuring and determining the length of the transfer material in the transport direction, a toner patch pattern suitable for the size of the transfer material is formed by forming a toner patch pattern on the back surface of the transfer material using a double-sided printing mechanism. can do.

  Further, in the third embodiment, since the exact length of the transfer material for forming the toner patch is determined and then the toner patch corresponding to the length is formed, wasteful consumption of the transfer material and toner is eliminated. be able to.

  In the third embodiment, in the color image forming apparatus having the double-sided printing mechanism, when the length of the transfer material in the transport direction is unknown, the transfer material is transported in the transfer direction using the double-sided print mechanism when executing the chromaticity control. In the case of a color image forming apparatus not provided with a double-sided printing mechanism, the length of the transfer material in the conveyance direction is measured during the normal printing operation, and the chromaticity is measured. When the control is executed, a toner patch pattern to be formed on the transfer material may be selected based on the length of the transfer material in the transport direction measured during the printing operation.

  In the above-described embodiment, the toner patch is formed by using a maximum of two transfer materials. However, when a transfer material for the third and subsequent sheets is required, the transfer materials are not limited to those transfer materials. This can be realized by the same process as the toner patch formation and chromaticity detection on the second transfer material.

1 is a structural cross-sectional view mainly showing a printer engine (image forming unit) of a color laser beam printer which is an example of a color image forming apparatus according to an embodiment of the present invention. 1 is a block diagram illustrating a configuration of a color image forming apparatus (color printer) according to an exemplary embodiment. 6 is a flowchart for explaining a process of measuring a length in a conveyance direction of a transfer material using a pre-registration sensor in the color image forming apparatus according to the embodiment. FIG. 4 is a diagram for explaining a transfer material conveyance state when measuring the length of the transfer material in the conveyance direction according to the flowchart of FIG. 3. 6 is a diagram illustrating an example of a toner patch pattern used in chromaticity control according to the first embodiment. FIG. 6 is a flowchart for explaining chromaticity detection processing using a color sensor when the length of a transfer material in the conveyance direction is unknown in the color image forming apparatus according to the first embodiment. FIG. 6 is a diagram illustrating an example of forming a toner patch pattern used in chromaticity control according to Embodiment 2 on a transfer material. 9 is a flowchart showing toner patch formation on a transfer material and chromaticity detection processing by a color sensor when the length of the transfer material in the conveyance direction is unknown in the color image forming apparatus according to Embodiment 2 of the present invention. . FIG. 6 is a structural cross-sectional view illustrating a configuration of an image forming unit of a color image forming apparatus according to Embodiment 3 of the present invention. , It is a figure explaining the conveyance operation of the transfer material at the time of double-sided printing in Embodiment 3 of this invention. FIG. 10 is a diagram illustrating a printing example of a toner patch on a transfer material in a color image forming apparatus according to a third embodiment of the present invention. 10 is a flowchart illustrating toner patch formation on a transfer material and chromaticity detection by a color color sensor in a color image forming apparatus according to Embodiment 3 of the present invention. It is a figure which shows an example of a structure of a density sensor. FIG. 6 is a diagram illustrating an example of a density or color matching control toner patch pattern formed on a transfer material.

Claims (14)

A transfer unit that transfers a visible image formed according to an image signal to a transfer material, and a density or chromaticity of a predetermined toner patch formed on the transfer material by the transfer unit is detected by a color sensor. A color image forming apparatus having image forming characteristic detecting means for detecting a forming characteristic,
A toner patch formed on the first transfer material is set to a first toner patch corresponding to the minimum size of the transfer material that can be imaged by the color image forming apparatus, and a visible image of the first toner patch is transferred to the transfer unit. First patch formation control means for forming
Detecting means for detecting a transfer direction size of the transfer material onto which a visible image of the first toner patch formed by the first patch formation control means is transferred;
Determining means for determining a second toner patch to be formed on a subsequent transfer material based on the transport direction size detected by the detecting means;
Second patch formation control means for forming the second toner patch determined by the determination means on a subsequent transfer material;
A color image forming apparatus comprising: A transfer unit that transfers a visible image formed according to an image signal to a transfer material, and a density or chromaticity of a predetermined toner patch formed on the transfer material by the transfer unit is detected by a color sensor. A color image forming apparatus having image forming characteristic detecting means for detecting a forming characteristic,
First patch formation control means for setting a toner patch to be formed on the first transfer material to a required maximum amount and forming a visible image of the first toner patch on the transfer means;
Detection means for detecting a transfer direction size of the transfer material to which a visible image of the first toner patch formed by the first patch formation control means is to be transferred;
An acquisition means for acquiring a toner patch amount actually transferred and formed on the first transfer material based on the transport direction size detected by the detection means;
Control means for controlling detection of the image formation characteristics by the image formation characteristic detection means in accordance with the toner patch amount acquired by the acquisition means;
A determining unit that determines a second toner patch to be formed on a subsequent transfer material based on the toner patch amount acquired by the acquiring unit and a transfer direction size of the transfer material detected by the detecting unit;
Second patch formation control means for forming the second toner patch determined by the determination means on a subsequent transfer material;
A color image forming apparatus comprising: A transfer unit that transfers a visible image formed according to an image signal to a transfer material, and a density or chromaticity of a predetermined toner patch formed on the transfer material by the transfer unit is detected by a color sensor. A color image forming apparatus having image forming characteristic detecting means for detecting a forming characteristic,
Detection means for detecting the transfer material size in the transfer direction;
First determination means for determining a first toner patch to be formed on the transfer material in accordance with the transfer direction size of the transfer material detected by the detection means;
First patch formation control means for forming the first toner patch determined by the first determination means on the transfer material by the transfer means;
Second determination means for determining a second toner patch to be formed on a subsequent transfer material based on the first toner patch formed on the transfer material and the transport direction size detected by the detection means;
Second patch formation control means for forming the second toner patch determined by the second determination means on a subsequent transfer material;
A color image forming apparatus comprising:   The total amount of the first and second toner patches corresponds to a toner patch amount necessary for detecting the image forming characteristics. Color image forming apparatus.   The formation of the second toner patch on a subsequent transfer material is omitted when the first toner patch corresponds to a toner patch amount necessary for detecting the image forming characteristic. Item 5. The color image forming apparatus according to any one of Items 1 to 4. Further comprising a double-sided image forming unit that enables image formation on both sides of the transfer material,
The detection means detects the length of the transfer material conveyed to the double-sided image forming unit,
The color image forming apparatus according to claim 3, wherein the first patch formation control unit forms the first toner patch on a back surface of the transfer material. The detection means includes
A sensor for detecting a leading edge and a trailing edge of the transfer material conveyed along a conveyance path;
A timer for measuring an elapsed time from the front end to the rear end of the transfer material detected by the sensor;
7. The color image forming apparatus according to claim 3, wherein a size in the conveyance direction of the transfer material is detected based on the elapsed time and the conveyance speed of the transfer material. A transfer unit that transfers a visible image formed in accordance with an image signal to a transfer material, and a density or chromaticity of a predetermined toner patch formed on the transfer material by the transfer unit is detected by a color sensor. A control method in a color image forming apparatus having image forming characteristic detecting means for detecting a forming characteristic,
A toner patch formed on the first transfer material is set to a first toner patch corresponding to the minimum size of the transfer material that can be imaged by the color image forming apparatus, and a visible image of the first toner patch is transferred to the transfer unit. A first patch formation control step for forming
A detection step of detecting a conveyance direction size of the transfer material onto which a visible image of the first toner patch formed in the first patch formation control step is transferred;
A determination step of determining a second toner patch to be formed on a subsequent transfer material based on the transport direction size detected in the detection step;
A second patch formation control step of forming the second toner patch determined in the determination step on a subsequent transfer material;
A control method in a color image forming apparatus. A transfer unit that transfers a visible image formed according to an image signal to a transfer material, and a density or chromaticity of a predetermined toner patch formed on the transfer material by the transfer unit is detected by a color sensor. A control method in a color image forming apparatus having image forming characteristic detecting means for detecting a forming characteristic,
A first patch formation control step of setting a toner patch to be formed on the first transfer material to a necessary maximum amount and forming a visible image of the first toner patch on the transfer means;
A detection step of detecting a transfer direction size of the transfer material to which a visible image of the first toner patch formed in the first patch formation control step is to be transferred;
An acquisition step of acquiring a toner patch amount actually transferred and formed on the first transfer material based on the transport direction size detected in the detection step;
A control step of controlling the detection of the image formation characteristics by the image formation characteristic detection means according to the toner patch amount acquired in the acquisition step;
A determination step of determining a second toner patch to be formed on a subsequent transfer material based on the toner patch amount acquired in the acquisition step and a conveyance direction size of the transfer material detected in the detection step;
A second patch formation control step of forming the second toner patch determined in the determination step on a subsequent transfer material;
A control method in a color image forming apparatus. A transfer unit that transfers a visible image formed according to an image signal to a transfer material, and a density or chromaticity of a predetermined toner patch formed on the transfer material by the transfer unit is detected by a color sensor. A control method in a color image forming apparatus having image forming characteristic detecting means for detecting a forming characteristic,
A detection process for detecting the transfer material size in the transfer direction;
A first determination step of determining a first toner patch to be formed on the transfer material according to the transport direction size of the transfer material detected in the detection step;
A first patch formation control step of forming the first toner patch determined in the first determination step on the transfer material by the transfer unit;
A second determination step of determining a second toner patch to be formed on a subsequent transfer material based on the first toner patch formed on the transfer material and the transport direction size detected in the detection step;
A second patch formation control step of forming the second toner patch determined in the second determination step on a subsequent transfer material;
A control method in a color image forming apparatus.   11. The total amount of the first and second toner patches corresponds to a toner patch amount necessary for detecting the image forming characteristics. Control method for color image forming apparatus.   The formation of the second toner patch on a subsequent transfer material is omitted when the first toner patch corresponds to a toner patch amount necessary for detecting the image forming characteristic. Item 12. A control method in a color image forming apparatus according to any one of Items 8 to 11. Further comprising a double-sided image forming unit that enables image formation on both sides of the transfer material,
In the detection step, the length of the transfer material conveyed to the double-sided image forming unit is detected,
The control method for a color image forming apparatus according to claim 10, wherein, in the first patch formation control step, the first toner patch is formed on a back surface of the transfer material. The detection step includes
Detecting the leading edge and the trailing edge of the transfer material conveyed along the conveying path;
Measuring the elapsed time from the front end to the rear end of the transfer material,
14. The control method in the color image forming apparatus according to claim 10, wherein the size in the conveyance direction of the transfer material is detected based on the elapsed time and the conveyance speed of the transfer material.

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