JP2012168437A - Image forming apparatus, image forming method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the number of samples of detected concentration values to improve the accuracy of detection of toner concentration, as well as eliminate influence on continuous printing operation to maintain the productivity, even when the intermediate transfer body is transferred at a low rate.SOLUTION: An image forming apparatus includes: a Y-pattern generation section 60 that forms a reference toner pattern for each photoreceptor and transfers the pattern onto an intermediate transfer belt 2; an M-pattern generation section 61; a C-pattern generation section 62; a Y-pattern detection sensor 10 that detects the concentration of a reference toner pattern formed through transfer onto the intermediate transfer belt 2; an M-pattern detection sensor 11; a C-pattern detection sensor 12; a rate control section 63 that changes a motion rate of the intermediate transfer belt 2 to a predetermined rate; and a concentration adjustment control section 52 that detects the concentration of the reference toner pattern after the motion rate of the intermediate transfer belt 2 is changed to the predetermined rate by the rate control section 63, and corrects the detected concentration value.

Description

  The present invention relates to an image forming apparatus, an image forming method, and a program having a direct transfer portion that performs monochrome printing and an indirect transfer portion that performs color printing.

  Conventionally, in a color image forming apparatus capable of both monochrome printing and full-color printing, when performing full-color printing, a color image is formed by superimposing a plurality of color images on the intermediate transfer body, and the intermediate transfer body is formed. There are two image forming means, an indirect transfer method for transferring the color image formed on the paper to the paper and a direct transfer method for transferring the black image directly to the paper. In such an apparatus, a technique is known in which the density of a reference toner pattern is detected by an optical toner density detection unit on a photoreceptor or a transfer belt, and the image density is corrected based on the detected density. Yes.

  For example, Patent Document 1 describes that a toner image transferred to a predetermined position on the surface of a transfer conveyance belt is detected. Further, FIG. 9 of Patent Document 1 discloses a configuration of an indirect transfer portion for color printing and a direct printing portion for monochrome printing. Japanese Patent Application Laid-Open No. 2005-228561 is intended to improve the accuracy of toner density detection, and discloses a technique for lowering the transfer material conveyance speed at the time of toner density detection than during normal image formation (printing). Yes.

  As described above, the image density correction of the image forming apparatus configured by the indirect transfer method or the direct transfer method cannot be printed while the density correction is performed on the configuration of the apparatus, and the correction is finished as soon as possible. In order to restart printing quickly, it is generally performed at the fastest conveyance speed and density detection is also performed at that speed. However, the detection accuracy of the toner density detection depends on the distance variation between the toner density detection unit and the measurement object, that is, the transfer body. Since the toner density detection is performed while the transfer body is being transported, the distance between the transfer body and the toner density detection unit is not always constant, and varies during the transport. In particular, when the conveyance speed is high, the fluctuation becomes large, and there is a problem that accuracy in density detection tends to deteriorate.

  In addition, when the conveyance speed is high at the time of toner density detection, if the number of samples for density detection is secured, the size of the reference toner pattern becomes relatively large, and thus there is a problem that the amount of toner consumption increases accordingly. . Further, when the conveyance speed is high, the time required for the reference toner pattern to pass through the toner density detection unit is shortened, so that there is a problem that the number of density value samples is reduced and density detection accuracy is lowered. Further, in the technique disclosed in Patent Document 1, when the above problem is solved by slowing the conveyance speed at the time of toner density detection, the continuous printing operation is also affected and productivity is reduced. There was a problem.

  The present invention has been made in view of the above, and in an image forming apparatus configured by a mixture of a direct transfer method and an indirect transfer method, when detecting the toner density of a reference toner pattern on an intermediate transfer member, the intermediate transfer Even when the body transport speed is low, the number of samples of the detected density value can be secured to improve the detection accuracy of toner density detection, and the productivity can be maintained without affecting the continuous printing operation. With the goal.

  It is another object of the present invention to reduce the amount of toner consumed at the time of toner density detection by reducing the reference toner pattern for toner density detection on the intermediate transfer member.

  In order to solve the above-mentioned problems and achieve the object, the present invention forms a monochrome image and transfers it to a recording paper, and forms each color image of YMC for each photoconductor. And an indirect transfer means for transferring the color image to a recording sheet via the transfer body, and a reference toner pattern for each photoconductor. Each color toner pattern forming means for transferring to the transfer body, each color density detecting means for detecting the density of a reference toner pattern formed by transferring to the transfer body, and the moving speed of the transfer body at a predetermined speed. When the speed change means for changing to the speed and each of the color density detection means detects the density of the reference toner pattern, the speed change means changes the moving speed of the transfer body to a predetermined speed before the change. It is detected by the color density detecting means, for a density correcting means for correcting the value of the detected concentration, comprising: a.

  The present invention secures the number of detected density value samples by delaying the transfer body of the indirect transfer portion and detecting the toner density by each color density detecting means in the direct transfer operation in which image formation by indirect transfer is not performed. Thus, the detection accuracy of toner density detection can be improved, and the productivity can be maintained without affecting the continuous printing operation.

FIG. 1 is an explanatory diagram showing a main configuration (at the time of direct transfer) of a direct transfer portion and an indirect transfer portion according to this embodiment. FIG. 2 is an explanatory diagram showing the main configuration (during indirect transfer) of the direct transfer unit and the indirect transfer unit according to this embodiment. FIG. 3 is a block diagram showing a hardware configuration of the image forming apparatus according to this embodiment. FIG. 4 is a block diagram showing a functional configuration of the image forming apparatus according to this embodiment. FIG. 5 is an explanatory diagram showing a main configuration of the toner density detection of the image forming apparatus according to this embodiment. FIG. 6 is an explanatory view showing an arrangement example of each photoconductor and each pattern detection sensor. FIG. 7 is an explanatory diagram showing the positions of the reference toner pattern transferred to the intermediate transfer belt and the pattern density sensor. FIG. 8 is an explanatory diagram illustrating the formation of a reference toner pattern and a detection example thereof when a failure occurs in the Y pattern detection sensor. FIG. 9 is an explanatory diagram illustrating an example in which each pattern detection sensor detects a reference toner pattern having the same density in Y color. FIG. 10 is an explanatory diagram showing the shape of a reference toner pattern in toner density detection performed by controlling the conveyance speed of the intermediate transfer belt. FIG. 11 is a flowchart showing toner density detection and correction operations on the intermediate transfer belt during the monochrome printing operation. FIG. 12 is a block diagram illustrating a hardware configuration of the image forming apparatus.

  Exemplary embodiments of an image forming apparatus, an image forming method, and a program according to the present invention will be explained below in detail with reference to the accompanying drawings.

(Embodiment)
In the image forming apparatus according to this embodiment, the direct transfer unit and the indirect transfer unit are configured to contact / separate each other in accordance with the formation of a monochrome image and the formation of a color image. FIGS. 1 and 2 are explanatory views showing the main configuration of a direct transfer unit and an indirect transfer unit according to this embodiment. FIG. 1 shows an example in which the transfer roller of the direct transfer unit is separated from the indirect transfer unit, and FIG. 2 shows an example in which the intermediate transfer belt of the indirect transfer unit is separated from the direct transfer unit. In the drawing, Y is an abbreviation for yellow, M for magenta, C for cyan, and K for black.

  1 and 2, reference numeral 1 is a direct transfer belt for transferring a monochrome image, reference numeral 2 is an intermediate transfer belt for transferring images of Y, M, and C, reference numeral 3 is an intermediate transfer belt roller, reference numeral 4 Is a Y photoconductor on which a Y-color electrostatic latent image is formed, symbol 5 is an M photoconductor on which an M-color electrostatic latent image is formed, and symbol 6 is a C-photosensitive on which a C-color electrostatic latent image is formed. No. 7 is a K photoconductor on which an electrostatic latent image of K color is formed, No. 8 is a direct transfer belt roller, No. 9 is a transfer roller, and No. 10 is a Y pattern detection sensor for detecting a reference toner pattern of Y color. Reference numeral 11 denotes an M pattern detection sensor that detects a reference toner pattern of M color, reference numeral 12 denotes a C pattern detection sensor that detects a reference toner pattern of C color, and reference numeral 13 denotes a K pattern detection that detects a reference toner pattern of K color. It is a sensor. Each of these pattern detection sensors uses, for example, an optical sensor composed of a light emitting element and a light receiving element.

  The direct transfer unit includes a direct transfer belt 1, a K photoconductor 7, a transfer roller 9, a transfer belt roller 8, a K pattern detection sensor 13, and the like for monochrome printing. The indirect transfer unit includes an intermediate transfer belt 2, a secondary transfer roller 3, a Y photoconductor 4, an M photoconductor 5, a C photoconductor 6, a Y pattern detection sensor 10, an M pattern detection sensor 11, and the like. C pattern detection sensor 12 and the like are included.

  In the image forming apparatus configured as described above, when performing monochrome printing, a K toner image is formed on the K photoconductor 7 and transferred to a sheet at the point of the transfer roller 9 by a direct transfer method. On the other hand, when performing color printing, Y, M, and C toner images are formed by the Y photoconductor 4, the M photoconductor 5, and the C photoconductor 6, and are superimposed on the intermediate transfer belt 2. The secondary transfer roller 3 approaches the transfer belt 1 directly to a position where it can be transferred to the paper during full-color printing, and Y, M, and C are applied to the paper during monochrome printing and pattern image formation for color matching control. When it is not necessary to transfer the toner image, the toner image is separated from the transfer belt 1 directly.

  FIG. 3 is a block diagram showing a hardware configuration of the image forming apparatus according to this embodiment. As shown in FIG. 3, the control system of the image forming apparatus includes a CPU 301, a RAM 302, a ROM 303, an I / O control unit 304, a transfer drive motor I / F 306a, a driver 307a, a transfer drive motor I / F 306b, and a driver 307b. Yes.

  The CPU 301 controls the entire apparatus including the reception of image data input from the controller 110 and the transmission / reception control of control commands. A RAM 302 used as a work memory, a ROM 303 for storing a control program for the CPU 301, and an I / O control unit 304 are connected to each other via a bus 309, and a data read / write process and contact / separation mechanism according to an instruction from the CPU 301. Various operations such as a motor, a clutch, a solenoid, and a sensor that drive each load 305 are executed, and a toner density is detected by a pattern detection sensor.

  In response to a drive command from the CPU 301, the transfer drive motor I / F 306a outputs a command signal that commands the drive frequency of the drive pulse signal to the driver 307a. The transfer drive motor M1 is rotationally driven according to this frequency. With this rotational drive, the drive roller is rotationally driven. Similarly, the transfer drive motor I / F 306b outputs a command signal that commands the drive frequency of the drive pulse signal to the driver 307b in response to a drive command from the CPU 301. The transfer drive motor M2 is rotationally driven according to this frequency. Note that the transfer drive motors M1 and M2 have a configuration in which the rotation speed can be variably controlled. For example, a stepping motor or a DC motor is used.

  The RAM 302 is used as a work area when executing a program stored in the ROM 303. Since this RAM 302 is a volatile memory, parameters used in the next belt drive such as amplitude and phase values are not shown. Data is stored in a nonvolatile memory such as EEPROM (Electrically Erasable Programmable Read Only Memory), etc., and data for one belt period is developed on RAM 302 using a sine function or approximate expression when the power is turned on or the transfer drive motor is driven. To do.

  The programs executed by the image forming apparatus according to the present embodiment are the units (print control unit 51, indirect transfer control unit 53, direct transfer control unit 54, secondary transfer control unit 55, and measurement unit 56) described later with reference to FIG. The module configuration includes an alignment control unit (not shown) and the like. As actual hardware, the CPU 301 reads out the program from the ROM 303 and executes the program so that each unit is loaded onto the main storage device and printed. A control unit 51, an alignment control unit, an indirect transfer control unit 53, a direct transfer control unit 54, a secondary transfer control unit 55, a measurement unit 56, and the like are generated on the main storage device.

  FIG. 4 is a block diagram showing a functional configuration of the image forming apparatus according to this embodiment. In FIG. 4, reference numeral 12Y is a Y image forming unit, reference numeral 12M is an M image forming unit, reference numeral 12C is a C image forming unit, reference numeral 12K is a K image forming unit, reference numeral 51 is a print control unit, reference numeral 52 is density adjustment control. , 53 is an indirect transfer control unit, 54 is a direct transfer control unit, 55 is a secondary transfer control unit, 56 is a measurement unit, and 15 is a secondary transfer unit.

  The K image forming unit 12K includes the K photoconductor 7 in FIG. 1, and the Y image forming unit 12Y, the M image forming unit 12M, and the C image forming unit 12C include the Y photoconductor 4, the M photoconductor 5, and C. A photoreceptor 6 is included. These image forming units are arranged in order according to the electrophotographic process, and this arrangement structure forms an electrostatic latent image according to image information, which is visualized by a developing device (not shown). To form a toner image.

  The direct transfer unit is configured to form a monochrome image by the K image forming unit 12K and transfer the monochrome image directly onto the transfer belt 1. The indirect transfer unit forms Y, M, and C images by the Y image forming unit 12Y, the M image forming unit 12M, and the C image forming unit 12C, and sequentially transfers the Y, M, and C images onto the intermediate transfer belt 2. Configured to do.

  The functional block shown here indicates a function or means realized by executing the program in this embodiment. The print control unit 51 includes an entire system, that is, a density adjustment control unit 52, an indirect transfer control unit 53, a direct transfer control unit 54, a secondary transfer control unit 55, a measurement unit 56, and the like in order to execute full color printing and monochrome printing. Control. The direct transfer control unit 54 controls the K-color image forming unit 12K during full color printing and monochrome printing to form a black toner image for direct transfer onto a transfer sheet. The indirect transfer control unit 53 controls the Y, C, and M color image forming units 12 (Y, C, and M) and the intermediate transfer belt 2 during full color printing, and transfers Y, M, and C to transfer paper. The toner image is formed.

  The secondary transfer control unit 55 controls the secondary transfer roller 3 (see FIG. 1) of the secondary transfer unit 15 to bring the secondary transfer roller 3 close to or away from the intermediate transfer belt 2, thereby causing the intermediate transfer belt to move. Y, M, and C toner images transferred to 2 are transferred to transfer paper.

  The secondary transfer control unit 55 brings the secondary transfer roller 3 close to a position where transfer onto the transfer paper is possible during full color printing. As a result, the Y, M, and C toner images superimposed on the intermediate transfer belt 2 by the indirect transfer method are transferred to the transfer paper at the point of the secondary transfer roller 3 of the secondary transfer unit 15. The secondary transfer control unit 55 does not need to transfer the Y, M, and C toner images onto the transfer paper during monochrome printing, and is thus separated from the intermediate transfer belt 2 (see FIG. 1). The secondary transfer control unit 55 does not need to transfer the Y, M, and C toner images onto the transfer paper when the density adjustment control pattern image is formed, so the secondary transfer roller 3 of the secondary transfer unit 15 is moved. To be separated from the transfer belt 1 directly. As will be described later, the density adjustment control unit 52 reads the reference toner pattern, detects the density of the pattern image for density adjustment control of the indirect transfer unit, or the density of the pattern image for density adjustment control of the direct transfer unit, and detects the detection. The image density is corrected based on the density.

  Next, an example in which the toner density of each of Y, M, and C in the indirect transfer portion is detected will be described in detail. FIG. 5 is an explanatory diagram showing a main configuration of the toner density detection of the image forming apparatus according to this embodiment. In FIG. 5, reference numeral 14 denotes a Y reference toner pattern for detecting the density of Y toner transferred to the intermediate transfer belt 2 after being formed on the Y photoconductor 4, and reference numeral 15 is after being formed on the M photoconductor 5. An M reference toner pattern for detecting the density of M toner transferred to the intermediate transfer belt 2, and a reference numeral 16, which is formed on the C photoconductor 6 and then transferred to the intermediate transfer belt 2 for detecting the density of C toner. Reference toner pattern, reference numeral 60 is a Y pattern generator for generating a Y reference toner pattern 14, reference numeral 61 is an M pattern generator for generating an M reference toner pattern 15, and reference numeral 62 is a C pattern generator for generating a C reference toner pattern 16. , 63 is a speed control unit for controlling the speed of the transfer drive motor M2 for driving the intermediate transfer belt 2, and 64 is a speed for measuring the moving speed of the intermediate transfer belt 2. It is a measuring unit. The speed controller 63 is realized by a driver 307b shown in FIG.

  The speed control unit 63 controls the transfer drive motor M2 so that the intermediate transfer belt 2 has a predetermined moving speed during the toner density detection process. Further, the transfer drive motor M2 is controlled so that the process speed determined at the time of actual color image formation is obtained. Further, the speed measuring unit 64 measures the moving speed of the intermediate transfer belt 2 as necessary. The speed measuring unit 64 is set to a speed (for example, normal transport linear speed: 200 mm / sec, transport linear speed at detection: 100 mm / sec as shown in FIG. 10 described later) by the speed control unit 63. If it is the structure controlled by switching, it is not particularly necessary.

  In FIG. 5, although not included in the configuration of this embodiment, the conventional toner concentration detection sensor 17 and the toner detection sensor of this embodiment (pattern detection sensors 10, 11, and 12 for each color) are arranged. In order to explain the difference in arrangement, the arrangement of the conventional toner density detection sensor 17 is illustrated.

  As shown in FIG. 5, Y, M, and C reference toner patterns 14, 15, 16 (pattern detection sensors 10, 11, 16 for each color) formed on the Y photoconductor 4, the M photoconductor 5, and the C photoconductor 6, respectively. The distance to 12) is shorter than the conventional distance. For example, if the distance to the conventional toner density detection sensor 17 is 75 × 2 + 15 + 75 = 240 mm, the Y reference toner pattern 14 formed on the Y photoconductor 4 is shortened to 37 mm.

  In the configuration shown in FIG. 5, the toner density is detected by the indirect transfer portion, and the toner density is corrected based on the detected toner density information. First, the speed controller 63 controls the secondary transfer belt 2 to a predetermined toner density detection speed. The Y pattern generation unit 60 forms a Y color toner pattern on the Y photoconductor 4. Thereafter, the Y pattern detection sensor 10 reads the Y reference toner pattern 14 transferred to the intermediate transfer belt 2 and inputs it to the density adjustment control unit 52 as toner density information. Similarly, for the M and C colors, the reference toner patterns are detected by the M and C pattern detection sensors 11 and 12. The density adjustment control unit 52 has a predetermined image density based on the toner density information of the reference toner patterns 14, 15, and 16 for Y, M, and C read by the pattern detection sensors 10, 11, and 12 for each color. The correction process is performed.

  FIG. 6 is an explanatory view showing an arrangement example of each photoconductor and each pattern density sensor. As shown in FIG. 6, the Y pattern density sensor 10 for the Y photoconductor 4 is the rear part (upper part in the drawing), the M pattern density sensor 11 for the M photoconductor 5 is the center, and the C pattern density sensor 12 for the C photoconductor 6. Each sensor is provided at a different position in the main scanning direction, such as a front part of the apparatus (lower part in the figure). In addition, this sensor arrangement example is not limited to this, Each sensor should just be a different position, respectively.

  FIG. 7 is an explanatory diagram showing the positions of the reference toner pattern transferred to the intermediate transfer belt and the pattern density sensor. As shown in this figure, in this embodiment, each pattern density sensor changes its position in the main scanning direction for each photoconductor, and the reference toner pattern is formed in accordance with the sensor position. The Y reference toner pattern 14 thus formed on the intermediate transfer belt 2 is read by the Y pattern density sensor 10. Similarly, the other M and C are optically read by the corresponding pattern density sensors, and density correction is executed based on the read toner density information.

  FIG. 8 is an explanatory diagram illustrating the formation of a reference toner pattern and a detection example thereof when a failure occurs in the Y pattern density sensor. Here, a case is shown in which it is regarded as a failure, for example, the sensor output is abnormal although the Y pattern density sensor 10 is in the detection state. As shown in FIG. 8, when the Y pattern density sensor 10 fails, a Y reference toner pattern 14 is formed at a position corresponding to the M pattern density sensor 11 and read by the M pattern density sensor 11. In this way, when a certain pattern density sensor fails, a reference toner pattern of a color corresponding to the failed sensor is formed at a sensor position that operates normally, and is read by the pattern density sensor, so that Y, M, C Toner density detection for each color is realized.

  FIG. 9 is an explanatory diagram showing an example in which each pattern density sensor detects a reference toner pattern having the same density in Y color. Here, as shown in FIG. 9, Y reference toner patterns 14a, 14b, and 14c having the same density are formed at main scanning positions that can be detected by the Y pattern density sensor 10, the M pattern density sensor 11, and the C pattern density sensor 12. To do. Thus, by forming a reference toner pattern having the same density in the main scanning direction and reading it by each pattern density sensor, it is possible to more accurately detect the toner density of the color in the main scanning direction.

  FIG. 10 is an explanatory diagram showing the shape of a reference toner pattern in toner density detection performed by controlling the conveyance speed of the intermediate transfer belt. 10A shows the case where the conveyance speed of the intermediate transfer belt 2 is 200 mm / sec, and FIG. 10B shows the case where the conveyance speed of the intermediate transfer belt 2 is 100 mm / sec. As shown in FIG. 10, when density detection is performed at a transport speed (B) that is slower than the speed of (A), even if the pattern length in the transport direction of the reference toner pattern is shortened (even if the pattern is small). It can be seen that a sufficient number of samples of detection values can be secured. That is, since the size of the reference toner pattern in the toner density correction can be reduced, the amount of toner consumed other than printing can be suppressed, and the running cost can be suppressed. The pattern length can be changed according to the conveyance linear velocity.

  FIG. 11 is a flowchart showing toner density detection and correction operations on the intermediate transfer belt during the monochrome printing operation. This operation is executed by the print control unit 51. First, it is determined whether monochrome printing by the direct transfer belt 1 is being executed (step S11). If it is determined that monochrome printing is in progress, the conveyance speed of the intermediate transfer belt 2 is controlled to 100 mm / sec, for example, as shown in FIG. 10 (step S12). Subsequently, the toner density detection operation described above is performed at this transport speed (step S14), and toner density correction is executed from the detected toner density (step S15). On the other hand, if it is determined in step S11 that monochrome printing is not being performed, the conveyance speed of the intermediate transfer belt 2 is not changed (step S13), the process proceeds to step S14, and toner density detection and toner density correction for K toner are executed.

  Thus, during the printing operation by the direct transfer method (monochrome printing), the secondary transfer roller 3 is in a state of being directly separated from the transfer belt 1 and the intermediate transfer belt 2 is in a state of not contributing to printing. . Therefore, only during monochrome printing, the drive motor of the intermediate transfer belt 2 is controlled to a linear speed at which density is easy to detect (slow conveyance linear speed) to detect density. As a result, it is possible to perform density detection with improved detection accuracy of the reference toner pattern while maintaining the productivity of monochrome printing. For printing other than monochrome printing (during color printing), the transfer speed of the intermediate transfer belt at the time of toner density detection is set as the printing speed, so that the influence on the printing operation due to toner density correction can be minimized.

  FIG. 12 is a block diagram illustrating a hardware configuration example of the image forming apparatus. As shown in the figure, this multifunction machine has a configuration in which a controller 210 and an engine unit (Engine) 260 are connected by a PCI (Peripheral Component Interface) bus. The controller 210 is a controller that controls the entire image forming apparatus and controls drawing, communication, and input from an operation unit (not shown). The engine unit 260 is a printer engine that can be connected to a PCI bus, and is, for example, a monochrome plotter, a 1-drum color plotter, a 4-drum color plotter, a scanner, or a fax unit. The engine unit 260 includes an image processing unit such as error diffusion and gamma conversion in addition to a so-called engine unit such as a plotter.

  The controller 210 includes a CPU 211, a north bridge (NB) 213, a system memory (MEM-P) 212, a south bridge (SB) 214, a local memory (MEM-C) 217, and an ASIC (Application Specific Integrated Circuit). 216 and a hard disk drive (HDD) 218, and the North Bridge (NB) 213 and the ASIC 216 are connected by an AGP (Accelerated Graphics Port) bus 215. The MEM-P 212 further includes a ROM (Read Only Memory) 212a and a RAM (Random Access Memory) 212b.

  The CPU 211 performs overall control of the image forming apparatus, has a chip set including the NB 213, the MEM-P 212, and the SB 214, and is connected to other devices via the chip set.

  The NB 213 is a bridge for connecting the CPU 211 to the MEM-P 212, SB 214, and the AGP bus 215, and includes a memory controller that controls reading and writing to the MEM-P 212, a PCI master, and an AGP target.

  The MEM-P 212 is a system memory used as a memory for storing programs and data, a memory for developing programs and data, a printer drawing memory, and the like, and includes a ROM 212a and a RAM 212b. The ROM 212a is a read-only memory used as a memory for storing programs and data, and the RAM 212b is a writable and readable memory used as a program / data development memory, a printer drawing memory, and the like.

  The SB 214 is a bridge for connecting the NB 213 to a PCI device and peripheral devices. The SB 214 is connected to the NB 213 via a PCI bus, and a network interface (I / F) unit and the like are also connected to the PCI bus.

  The ASIC 216 is an IC (Integrated Circuit) for image processing having hardware elements for image processing, and has a role of a bridge for connecting the AGP bus 215, the PCI bus, the HDD 218, and the MEM-C 217. The ASIC 216 includes a PCI target and an AGP master, an arbiter (ARB) that forms the core of the ASIC 216, a memory controller that controls the MEM-C 217, and a plurality of DMACs (Direct Memory) that rotate image data using hardware logic. (Access Controller) and a PCI unit that performs data transfer between the engine unit 260 via the PCI bus. The ASIC 216 is connected to an FCU (Facsimile Control Unit) 230, a USB (Universal Serial Bus) 240, and an IEEE 1394 (the Institute of Electrical and Electronics 13) interface via a PCI bus. The operation display unit 220 is directly connected to the ASIC 216.

  The MEM-C 217 is a local memory used as a copy image buffer and a code buffer, and an HDD (Hard Disk Drive) 218 is a storage for storing image data, programs, font data, and forms. It is.

  The AGP bus 215 is a bus interface for a graphics accelerator card proposed for speeding up graphics processing. The AGP bus 215 speeds up the graphics accelerator card by directly accessing the MEM-P 212 with high throughput. It is.

  A program executed in the image forming apparatus of this embodiment is a file in an installable format or an executable format, and is a computer such as a CD-ROM, a flexible disk (FD), a CD-R, a DVD (Digital Versatile Disk). Recorded on a readable recording medium. Further, the program executed in the image forming apparatus of this embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. The image forming program executed by the image forming apparatus according to this embodiment may be provided or distributed via a network such as the Internet.

  Further, the program according to this embodiment may be provided by being incorporated in advance in a ROM or the like. The program executed by the image forming apparatus according to the present embodiment has a module configuration including each part of the above-described image forming apparatus. As actual hardware, a CPU (processor) reads the image forming program from the storage medium. By executing the above, the above-described units are loaded onto the main storage device and generated on the main storage device.

DESCRIPTION OF SYMBOLS 1 Direct transfer belt 2 Intermediate transfer belt 4 Y photoconductor 5 M photoconductor 6 C photoconductor 7 K photoconductor 10 Y pattern detection sensor 11 M pattern detection sensor 12 C pattern detection sensor 13 K pattern detection sensor 14 Y reference toner pattern 15 M reference toner pattern 16 C reference toner pattern 51 Print control unit 52 Density adjustment control unit 60 Y pattern generation unit 61 M pattern generation unit 62 C pattern generation unit 63 Speed control unit

JP 2009-25814 A JP 2003-131538 A

Claims (8)

A direct transfer means for forming a monochrome image and transferring it to the recording paper, and forming an image of each color of YMC for each photoconductor, transferring the image to the transfer body to form a color image, An indirect transfer means for transferring to a recording paper via a transfer body,
Each color toner pattern forming means for forming a reference toner pattern for each photoconductor and transferring it to the transfer body;
Each color density detecting means for detecting the density of a reference toner pattern formed by transferring to the transfer body;
Speed changing means for changing the moving speed of the transfer body to a predetermined speed;
When each of the color density detecting means detects the density of the reference toner pattern, the speed changing means changes the moving speed of the transfer body to a predetermined speed, and then the color density detecting means detects the detected density. Density correction means for correcting the density value;
An image forming apparatus comprising: The color density detection means are arranged at different positions in the main scanning direction,
2. The image forming apparatus according to claim 1, wherein each color toner pattern forming unit forms a reference toner pattern at a position corresponding to each color density detecting unit arranged in the main scanning direction.   3. The image formation according to claim 2, wherein each of the color toner pattern forming units forms a reference toner pattern of the same color and the same density at a position corresponding to each color density detection unit arranged in the main scanning direction. apparatus.   Each color toner pattern forming unit forms a reference toner pattern at a position that can be detected by each of the other color toner pattern forming units when each color density detection unit cannot obtain a predetermined detection output. The image forming apparatus according to claim 2.   The speed changing means changes the moving speed to a lower moving speed than the moving speed of the transfer body during image formation when the density of the reference toner pattern is detected by each color density detecting means. The image forming apparatus according to any one of 4.   Each of the color toner pattern forming means is a reference toner pattern having a minimum size capable of detecting the density of the reference toner pattern by each color density detecting means in accordance with the moving speed of the transfer body by the speed changing means. The image forming apparatus according to claim 5, wherein the image forming apparatus is formed. A direct transfer means for forming a monochrome image and transferring it to the recording paper, and forming an image of each color of YMC for each photoconductor, transferring the image to the transfer body to form a color image, An image forming method executed by an image forming apparatus having an indirect transfer means for transferring to a recording sheet via a transfer body,
Each color toner pattern forming means forms a reference toner pattern for each of the photoconductors, and transfers each color toner pattern to the transfer body;
Each color density detection unit detects each density of a reference toner pattern formed by being transferred to the transfer body;
A speed changing step for changing the moving speed of the transfer body to a predetermined speed;
When the density correction unit detects the density of the reference toner pattern in each of the color density detection processes, the transfer speed of the transfer body is changed to a predetermined speed by the speed change process, and then detected in each color density detection process. A density correction process for correcting the detected density value;
An image forming method comprising: A direct transfer means for forming a monochrome image and transferring it to the recording paper, and forming an image of each color of YMC for each photoconductor, transferring the image to the transfer body to form a color image, A program for causing a computer to have an indirect transfer means for transferring to a recording sheet via a transfer body,
Each color toner pattern forming step of forming a reference toner pattern for each of the photoconductors and transferring it to the transfer body;
Each color density detection step for detecting the density of a reference toner pattern formed by being transferred to the transfer body;
A speed changing step for changing the moving speed of the transfer body to a predetermined speed;
When the density of the reference toner pattern is detected in each color density detection step, the transfer speed of the transfer body is changed to a predetermined speed by the speed change step, and then detected in each color density detection step. A density correction step for correcting the density value;
A program for running

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