JP2009053668A - Image forming apparatus and image density adjusting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve convenience by shortening the adjustment time of image density, thereby reducing the waiting time of a user. <P>SOLUTION: An image forming apparatus is provided with a transfer belt 1; photosensitive members 4Y, 4M, 4C and 4Bk which form a black adjustment pattern and a color adjustment pattern on the transfer belt 1; a pattern detection sensor 2, which detects the black adjustment pattern and the color adjustment pattern; a monochrome adjustment section which adjusts the image density of black; a color adjustment section which adjusts the image density of yellow, cyan and magenta; and an adjustment operation determination section which determines whether only adjustment by the monochrome adjustment section is performed, or only the adjustment by the color adjustment section is performed, based on the color of an image formed on a recording paper. The monochrome adjustment section adjusts the image density of black, when the black adjustment pattern is formed, and the color adjustment section adjusts the image density of yellow, cyan and magenta, when the color adjustment pattern is formed. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus and an image density adjusting method capable of forming a full-color image by superimposing a plurality of colors and forming a monochrome image only with black.

  In a conventional image forming apparatus (particularly, a tandem electrophotographic image forming apparatus), a black-and-white image is formed using only black as a function for forming and printing a black-and-white (monochrome) image for reasons such as extending the life of the image carrier. A mode for forming an image (hereinafter referred to as “monochrome mode”) is provided. In addition to the monochrome mode, there is also a function for forming and printing a color image that includes a mode for forming a full color image by superimposing a plurality of colors (hereinafter referred to as “color mode”). (For example, refer to Patent Document 1).

  In an image forming apparatus having such a monochrome mode and a color mode, feedback control is performed by forming a pattern of image patches (adjustment patches) on a transfer belt and reading the density of the formed pattern with a sensor. Some are equipped with image quality adjustment means. Conventionally, in the case of a four-color machine of a plurality of colors, for example, yellow (Y), magenta (M), cyan (C), and black (Bk), image density adjustment (color adjustment) of the four colors is performed simultaneously. It was.

JP-A-7-66953

  However, since a color image cannot be formed when the monochrome mode is set, it is necessary to temporarily switch from the monochrome mode to the color mode when performing color adjustment. The time required for this switching is not what the user (operator) desires.

  Therefore, there are many image forming apparatuses that do not perform color adjustment when the monochrome mode is set. In such an image forming apparatus, even when color adjustment is necessary, color adjustment is not performed when the monochrome mode is set. For example, when the mode is suddenly switched from the monochrome mode to the color mode, switching is performed. Sometimes color adjustment is performed, and the time required for this color adjustment becomes a user's time.

  Further, in Patent Document 1, an image forming apparatus that performs color misregistration correction by forming a correction pattern on a transfer body and reading it is disclosed. This is a color that considers switching between a monochrome mode and a color mode. Misalignment correction is not performed.

  The present invention has been made in view of the above, and in the case of forming a black image, the image density of only black is adjusted, and in the case of forming an image of a color other than black, a color other than black is used. By adjusting only the image density, it is possible to shorten the adjustment time of the image density of black and other colors, reduce the waiting time of the user, and improve the convenience, and the image forming apparatus and image An object is to provide a density adjustment method.

In order to solve the above-described problems and achieve the object, the present invention provides an image forming apparatus that forms an image by superimposing a plurality of colors, and an image carrier and a predetermined image density through the image carrier. Writing means for forming an image on a recording medium and forming a first pattern of black having different densities and a second pattern of colors other than black and having different densities on the image carrier; First detecting means for detecting the first pattern and the second pattern formed on the image carrier, and a first image adjusting black image density at the time of image formation based on the detected first pattern. Adjusting means; second adjusting means for adjusting image densities of a plurality of colors other than black at the time of image formation based on the detected second pattern; and color of an image formed on the recording medium Adjustment operation determining means for determining whether to perform only adjustment by the first adjustment means or only adjustment by the second adjustment means, based on the first adjustment means, the first adjustment means, When the first pattern is formed on the image carrier, the image density of black is adjusted, and when the second pattern is formed on the image carrier, the second pattern is adjusted to a plurality of colors other than black. The image density of the color is adjusted.

  The present invention also relates to an image density adjusting method executed by an image forming apparatus that forms an image by superimposing a plurality of colors, wherein the image forming apparatus includes an image carrier and the image carrier with a predetermined image density. Writing means for forming, on the image carrier, an image on a recording medium and forming a black first pattern having different densities and a second pattern having a plurality of colors other than black and having different densities. And first detection means for detecting the first pattern and the second pattern formed on the image carrier, and based on the detected first pattern, the black image density at the time of image formation A first adjustment step of adjusting the image density of a plurality of colors other than black during image formation based on the detected second pattern, An adjustment operation determination step for determining whether to perform only the adjustment in the first adjustment step or only the adjustment in the second adjustment step based on the color of the image formed on the recording medium; and the writing unit Therefore, when it is determined that only the adjustment by the first adjustment step is executed, the first pattern is formed on the image carrier, and when it is determined that only the adjustment by the second adjustment step is executed, An image forming step of forming two patterns on the image carrier, wherein the first adjustment step adjusts an image density of black when the first pattern is formed on the image carrier, In the second adjustment step, when the second pattern is formed on the image carrier, the image density of a plurality of colors other than black is adjusted.

  According to the present invention, when black image formation is performed, adjustment of image density of only black is performed, and when image formation of colors other than black is performed, adjustment of image density of only colors other than black is performed. As a result, it is possible to shorten the adjustment time of the image density of black and a color other than black, reduce the waiting time of the user, and improve the convenience.

  Exemplary embodiments of an image forming apparatus and an image density adjusting method according to the present invention are explained in detail below with reference to the accompanying drawings. In the following embodiments, an example in which the image forming apparatus of the present invention is applied to a four-tandem electrophotographic printer (hereinafter referred to as “printer”) is shown, but the present invention is not limited to this. The present invention can also be applied to a copying machine having a function for performing printing and color printing, and a multi-function peripheral (MFP) in which a plurality of functions such as copying, faxing, and printers are housed in one housing. Can do. In the following embodiments, a color image is printed by superimposing four colors of yellow, magenta, cyan, and black. However, the present invention is not limited to this. It is good also as a structure which prints an image.

(Embodiment 1)
The printer according to this embodiment prints a color image by superimposing a plurality of colors, and prints a monochrome image using black.

  First, the image forming unit of the printer in this embodiment will be described. FIG. 1 is a configuration diagram illustrating an example of an image forming unit of the printer 100 according to the first embodiment. As shown in FIG. 1, in the image forming unit, four photoconductors 4Y (yellow), 4M (magenta), 4C (cyan), and 4Bk (black) are arranged in a line along the transfer belt 1, and further secondary A transfer unit 3 and a pattern detection sensor 2 are provided. In this printer, a monochrome image is printed with black, and a color image is printed with four colors of yellow, cyan, magenta, and black. The photoconductors 4Y, 4M, 4C, and 4Bk are the writing means of the present invention, the photoconductor 4Bk is the first writing means of the present invention, and the photoconductors 4Y, 4M, and 4C are the second writing means of the present invention. It is.

  The photoreceptor 4Bk transfers a black printed image toner image to the transfer belt 1 at a predetermined image density, thereby forming a monochrome image. The photoreceptors 4Y, 4M, 4C, and 4Bk transfer toner images of yellow, cyan, magenta, and black print images to the transfer belt 1 at a predetermined image density, and these toner images are sequentially superimposed on the transfer belt 1. A color image is formed by transferring the images together.

  Further, the photoreceptor 4Bk forms a black adjustment pattern on the transfer belt 1 in which a plurality of black adjustment patches having different densities are arranged. Further, the photoreceptors 4Y, 4M, and 4C form a color adjustment pattern on the transfer belt 1 in which a plurality of adjustment patches of yellow, cyan, and magenta having different densities are arranged. The black adjustment pattern and the color adjustment pattern are referred to as an adjustment pattern, and details of the adjustment pattern will be described later.

  The pattern detection sensor 2 is disposed on the upper right side of the transfer belt 1, and irradiates the transfer belt 1 with irradiation light at the timing when the black adjustment pattern and the color adjustment pattern formed on the transfer belt 1 pass. The adjustment pattern is detected by receiving the reflected light. Based on this detection result, feedback is made to the transfer bias, development / charging bias, etc., and the image density for each color is adjusted, and the image is printed with an appropriate predetermined density.

  The secondary transfer unit 3 transfers the print image formed on the transfer belt 1 to a recording sheet conveyed from a paper supply cassette (not shown).

  Note that the distance from the adjustment pattern formation position by the photoconductor 4Bk to the adjustment pattern detection position by the pattern detection sensor is L1, and the distance between the adjustment pattern formation positions of the adjacent photoconductors is L2.

  Next, the printer in this embodiment will be described. FIG. 2 is a diagram illustrating an example of the configuration of the printer 100. As shown in FIG. 2, the printer 100 includes a controller 101 that performs various control processes such as a control process of each unit of the printer 100 and an image forming process (print process). An operation panel 120 and a printer engine 130 are connected to the controller 101.

  The operation panel 120 is an operation display unit that accepts operations on displayed items, and has a UI (user interface) that can change the status (printer status information) display, print mode, and print conditions of the printer 100. ing.

The printer engine 130 includes the image forming unit as described above, and forms an image by an electrophotographic process method and prints a monochrome image or a color image on a recording sheet fed from a sheet feeding tray. Is.

The controller 101 is a generic name for control mechanisms that convert print data into drawing data and output the drawing data to the printer engine 130, and includes the following modules. The controller 101 includes a CPU (Central Processing Unit) 102 that controls the operation of the printer 100.
Is provided.

  The CPU 102 includes a ROM (Read Only Memory) 103 for storing a program executed by the CPU 102 and necessary data, and a RAM (Random Access Memory) 104 for configuring a work area of the CPU 102. 105 is connected. The RAM 104 is used as a buffer for managing print data in units of pages and temporarily storing it, a bitmap memory for converting the print data stored in the buffer into an actual print drawing image, and storing video data, and the like. .

Further, the CPU 102 includes a communication control unit 106 and an HDD (Hard Disk Drive) 107.
The engine control unit 108, the NV-RAM 109, the medium control unit 110, and the UI control unit 111 are connected via an internal bus 105, and data exchange between these elements is mainly via the internal bus 105. Done.

  The NV-RAM 109 is a non-volatile memory that stores information used for control by the CPU 102 regardless of power ON / OFF.

  The UI control unit 111 connects the operation panel 120 and exchanges data with a UI (user interface) displayed on the operation panel 120.

  The communication control unit 106 is an interface card incorporated in order to connect the printer 100 to a LAN (Local Area Network) cable, a USB (Universal Serial Bus) cable, or the like. For example, the communication control unit 106 connects a PC (Personal Computer) 150 which is an external device via a LAN cable, receives print data from the PC 150, transmits print result information to the PC 150, and the like. Perform the action.

The HDD 107 stores various print information and stores other appropriate information files and the like. In addition, the HDD 107 includes an OS (Operating System).
), Various application programs running on the OS are stored. In the present embodiment, a print processing program or the like is stored as an application program.

  The engine control unit 108 is an interface that transmits a control signal from the CPU 102 to the printer engine 130 and receives an engine status signal from the printer engine 130 to the CPU 102.

  The medium control unit 110 indicates an interface or an insertion slot for a non-volatile storage medium 140 that is a removable external recording medium (for example, an SD card). When the storage medium 140 is inserted into this slot, it is possible to recognize whether or not the storage medium 140 is inserted by a change in voltage or the like (hot-line insertion / extraction).

The printer 100 having such a configuration reads an OS from the HDD 107 into the RAM 104 when the user turns on the power, and starts the OS. The OS activated in this way activates an application program, reads information, and stores information in response to a user operation. In addition, the application program is not limited to one that runs on a predetermined OS, but may be one that causes the OS to execute a part of various processes described later, or constitutes a predetermined application program or OS. It may be included as part of a group of program files.

  Next, the control of the entire controller executed by the controller 101 will be described. FIG. 3 is a block diagram illustrating a functional configuration of the controller 101 in the printer 100 according to the first embodiment.

  The controller 101 mainly includes a monochrome adjustment unit 201, a color adjustment unit 202, and an adjustment operation determination unit 203, to which an NV-RAM 109 is connected.

  The NV-RAM 109 stores appropriate image density values of predetermined colors (Y, M, C, Bk).

  When the black adjustment pattern is formed on the transfer belt 1 by the photoconductor 4Bk or the like, and the black adjustment pattern is detected by the pattern detection sensor 2, the monochrome adjustment unit 201 is based on the detected black adjustment pattern at the time of image formation. The black image density is adjusted with reference to the NV-RAM 109. The adjustment will be described in detail below.

  FIG. 4 is a diagram illustrating an example of a black adjustment pattern for adjusting black (Bk). As shown in FIG. 4, the black adjustment pattern is an adjustment pattern in which ten black adjustment patches having different densities are arranged in a gradation from the top to the bottom. The black adjustment pattern is formed so that adjustment patches are arranged in the sub-scanning direction of the transfer belt 1 by the photoconductor 4Bk or the like that has received an instruction from the controller 101. When the black adjustment pattern is detected by the pattern detection sensor 2, the monochrome adjustment unit 201 measures the black image density and refers to the detected black adjustment pattern density and the image density stored in the NV-RAM 109. Then, the image density of black is adjusted by performing feedback control. Note that the feedback control method is performed by a conventionally known method, and a description thereof is omitted here.

  When a color adjustment pattern is formed on the transfer belt 1 by the photoconductors 4Y, 4M, and 4C and the color adjustment pattern is detected by the pattern detection sensor 2, the color adjustment unit 202 performs image processing based on the detected color adjustment pattern. The image density of yellow, cyan, and magenta at the time of formation is adjusted with reference to the NV-RAM 109. The adjustment will be described in detail below.

  FIG. 5 is a diagram illustrating an example of a color adjustment pattern for simultaneously adjusting three colors of yellow (Y), magenta (M), and cyan (C). As shown in FIG. 5, the color adjustment pattern is an adjustment pattern in which 10 adjustment patches of different colors are arranged in parallel in a gradation from the top to the bottom. The color adjustment pattern is formed so that adjustment patches are arranged in the sub-scanning direction of the transfer belt 1 by the photoreceptors 4Y, 4M, 4C, and the like that have received an instruction from the controller 101. When the color adjustment pattern is detected by the pattern detection sensor 2, the color adjustment unit 202 measures the image density of each color, and refers to the detected color adjustment pattern density and the image density stored in the NV-RAM 109. Then, the image density of yellow, cyan, and magenta is adjusted by performing feedback control. As with the above, description of the feedback control method is omitted.

The adjustment operation determination unit 203 determines that an image density adjustment operation is necessary when a predetermined time has elapsed, and performs only the adjustment by the monochrome adjustment unit 201 based on the color of the image formed on the recording paper. It is determined whether to execute or only the adjustment by the color adjustment unit 202 is executed. This will be described in detail below with reference to the drawings.

  The adjustment operation determination unit 203 determines whether a monochrome image or a color image is printed depending on whether the photoreceptors 4Y, 4M, and 4C are separated from or in contact with the transfer belt 1. Therefore, first, the case where the photoreceptors 4Y, 4M, 4C and the transfer belt 1 are separated from each other and the case where they are in contact with each other will be described. 6 and 7 are diagrams illustrating an example of the image forming unit of the printer 100 according to the first embodiment.

  As described in FIG. 1, the photoconductors 4Y, 4M, 4C, and 4Bk are arranged in a line along the transfer belt 1. As shown in FIG. 6, transfer rollers 5Y, 5M, 5C, and 5Bk are arranged on the opposite sides of the respective photoreceptors 4Y, 4M, 4C, and 4Bk through the transfer belt 1, respectively. The transfer rollers 5Y, 5M, and 5C are fixed to the fixed member 8 at equal intervals while the roller portion is rotatable. The fixing member 8 can be rotated around the fulcrum F by the driving force of the DC brush motor 7 and the rotation of the cam 6.

  In the image forming unit, a position detection sensor (not shown) for detecting whether the photoreceptors 4Y, 4M, and 4C and the transfer belt 1 are separated or in contact with each other is provided near the transfer roller 5 or the cam 6. Is provided. For example, when the position detection sensor detects that the photoreceptors 4Y, 4M, and 4C are separated from the transfer belt 1, a signal indicating that the position has been switched from ON to OFF is sent to the adjustment operation determination unit 203 of the controller 101. When it is detected that the photoconductors 4Y, 4M, and 4C are in contact with the transfer belt 1, a signal indicating that switching from OFF to ON is sent to the adjustment operation determination unit 203 of the controller 101.

  When the position detection sensor detects that the photoconductors 4Y, 4M, and 4C are in contact with the transfer belt 1, as shown in FIG. 6, the transfer rollers 5Y, 5M, 5C, and 5Bk and the photoconductors 4Y, 4M, 4C and 4Bk are all in contact via the transfer belt 1. Accordingly, since the photoconductors 4Y, 4M, and 4C are in a state in which the toner image of the print image can be transferred to the transfer belt 1, the printer is in a state of printing a color image on the recording paper. Accordingly, the adjustment operation determination unit 203 determines that only the adjustment by the color adjustment unit 202 is performed when a signal indicating that the photoreceptors 4Y, 4M, and 4C are in contact with the transfer belt 1 is received. When this determination is made, the photoreceptors 4Y, 4M, and 4C form a color adjustment pattern on the transfer belt 1, and the color adjustment unit 202 adjusts the image densities of yellow, cyan, and magenta. Further, in FIG. 6, when the cam 6 is rotated in the direction of the arrow R1, the fixing member 8 is rotated around the fulcrum F to be in the state shown in FIG.

  When the position detection sensor detects that the photoconductors 4Y, 4M, and 4C are separated from the transfer belt 1, only the transfer roller 5Bk and the photoconductor 4Bk pass through the transfer belt 1 as shown in FIG. It will be in contact. Therefore, since the photoconductors 4Y, 4M, and 4C cannot transfer the toner image of the print image to the transfer belt 1, the printer is printing a monochrome image on the recording paper. Accordingly, the adjustment operation determination unit 203 determines that only the adjustment by the monochrome adjustment unit 201 is performed when a signal indicating that the photoreceptors 4Y, 4M, and 4C are separated from the transfer belt 1 is received. When the determination is made, the photoreceptor 4Bk forms a black adjustment pattern on the transfer belt 1, and the black image density is adjusted by the monochrome adjustment unit 201. In FIG. 7, when the cam 6 is rotated in the direction of the arrow R2, the fixing member 8 rotates about the fulcrum F and returns to the state shown in FIG.

  As described above, the adjustment operation determination unit 203 determines that only the adjustment by the monochrome adjustment unit 201 is performed when the photoreceptors 4Y, 4M, and 4C and the transfer belt 1 are separated from each other. On the other hand, when the photoreceptors 4Y, 4M, and 4C are in contact with the transfer belt 1, the adjustment operation determination unit 203 determines that only the adjustment by the color adjustment unit 202 is performed.

  The adjustment operation determination unit 203 according to the present embodiment determines whether or not an image density adjustment operation is necessary depending on whether or not a predetermined time has elapsed. However, the present invention is not limited to this. There is no. In other words, the image density adjustment operation may be determined based on a predetermined number of printed sheets and temperature.

  Next, first, adjustment time when image density adjustment in the prior art, that is, image density adjustment of all four colors of yellow (Y), magenta (M), cyan (C), and black (Bk) is performed simultaneously. Then, the monochrome and color image density adjustment time of the printer of this embodiment will be described.

  FIG. 8 is an example of a timing chart showing image density adjustment time in the prior art. In the timing charts in the following embodiments, it is assumed that the timings for forming the adjustment patterns of the respective colors are lowered by the photoreceptors 4Y, 4M, 4C, and 4Bk. Similarly, it is assumed that pattern detection by the pattern detection sensor 2 is also performed when the pattern detection sensor 2 is low.

  In a conventional printer, when printing a color image, the image density is adjusted for all colors (here, four colors Y, M, C, and Bk). Therefore, as shown in FIG. 8, first, an adjustment pattern of yellow (Y) is formed on the transfer belt 1 by the photoreceptor 4Y. Then, after a lapse of time until the transfer belt 1 at the adjustment pattern formation position by the photoreceptor 4Y reaches the formation position of the photoreceptor 4M (after the passage of the time of the distance L2 in FIG. 1), the photoreceptor. By 4M, a magenta (M) adjustment pattern is formed on the transfer belt 1. Similarly, adjustment patterns of other colors are also formed in the order of cyan (C) and black (Bk).

  Here, an adjustment pattern using four colors of yellow (Y), magenta (M), cyan (C), and black (Bk) will be described. FIG. 9 is a diagram illustrating an example of an adjustment pattern in the prior art. As shown in FIG. 9, in this adjustment pattern, ten adjustment patches of different colors having different densities are arranged in parallel in a gradation from the upper part to the lower part. This adjustment pattern is formed so that the adjustment patches are arranged in the sub-scanning direction of the transfer belt 1 by the photoreceptors 4Y, 4M, 4C, 4Bk, and the like. When this adjustment pattern is detected by the sensor, the image density of each color is adjusted.

  Then, an adjustment pattern for each of the four colors is formed on the transfer belt 1 in the order of Y, M, C, and Bk, and after a certain period of time has elapsed since the formation of the adjustment pattern for the last color (Bk of the fourth color) is started, Adjustment patterns for each color are detected. This fixed time is a time (a time corresponding to a distance L1 in FIG. 1) from when the transfer belt 1 reaches the detection position by the pattern detection sensor from the position where the last color adjustment pattern is formed. Strictly speaking, it is necessary to estimate the time for the start of charging and the start of exposure for each color, but these times are omitted in the present embodiment.

  Here, the time taken from the start of image density adjustment to the end of adjustment (image density adjustment time) is the time after the start of the adjustment pattern of the first color (here, yellow (Y)) on the transfer belt 1. The adjustment time until all the adjustment patterns are detected by the pattern detection sensor 2 and the adjustment of the image density by the monochrome adjustment unit 201 or the color adjustment unit 202 is completed. The same applies to the following embodiments.

Next, the adjustment time of the image density of yellow, cyan, and magenta by the printer of this embodiment will be described. FIG. 10 is an example of a timing chart showing the adjustment time of the image density of yellow, cyan, and magenta in the first embodiment.

  In the printer of this embodiment, as described above, when printing a color image, the image density is adjusted for colors other than black (here, three colors Y, M, and C). Therefore, as shown in FIG. 10, first, a yellow (Y) adjustment pattern is formed on the transfer belt 1 by the photoreceptor 4Y. Then, after a lapse of time until the transfer belt 1 at the adjustment pattern formation position by the photoreceptor 4Y reaches the formation position of the photoreceptor 4M (after the passage of the time of the distance L2 in FIG. 1), the photoreceptor. By 4M, a magenta (M) adjustment pattern is formed on the transfer belt 1. In the same manner, a cyan (C) adjustment pattern is formed. As described above, the black (Bk) adjustment pattern is not formed.

  Then, an adjustment pattern for each of the three colors in the order of Y, M, and C is formed on the transfer belt 1, and after a predetermined time has elapsed since the formation of the adjustment pattern for the last color (C of the third color) has started, Adjustment patterns are detected. Note that the predetermined time is the same as in the prior art.

  Here, compared with the timing chart of the prior art (FIG. 8), in the present embodiment, since the black adjustment pattern is not formed, the start of the detection timing by the pattern detection sensor 2 is accordingly accelerated. Yes. Therefore, it is possible to shorten the image density adjustment time for yellow, cyan, and magenta compared to the image density adjustment time in the prior art.

  Next, a monochrome image density adjustment time by the printer of this embodiment will be described. FIG. 11 is an example of a timing chart showing the monochrome image density adjustment time in the first embodiment.

  In the printer of this embodiment, as described above, when printing a monochrome image, the image density is adjusted only for black. Therefore, as shown in FIG. 11, a black (Bk) adjustment pattern is formed on the transfer belt 1 by the photoreceptor 4 </ b> Bk. As described above, the adjustment patterns of yellow (Y), magenta (M), and cyan (C) are not formed.

  Then, after a predetermined time has elapsed after the Bk adjustment pattern is formed, the black adjustment pattern is detected. Note that the predetermined time is the same as in the prior art.

  Here, compared with the timing chart of the prior art (FIG. 8), in the present embodiment, the adjustment pattern of yellow (Y), magenta (M), and cyan (C) is not formed, and accordingly, the pattern is increased accordingly. The start of the detection timing by the detection sensor 2 is earlier. Therefore, the monochrome image density adjustment time can be shortened compared to the image density adjustment time in the prior art. Compared with the timing chart of the image density of yellow, cyan, and magenta (FIG. 10), the adjustment of the monochrome image density is performed only for black, so the adjustment time of the monochrome image density is yellow, cyan. The magenta image density adjustment time is shorter.

  Next, print processing by the printer of this embodiment will be described. FIG. 12 is a flowchart illustrating a flow of printing processing by the printer 100 according to the first embodiment.

First, the printer engine 130 prints one color or monochrome image (step S11). Then, the adjustment operation determination unit 203 determines whether or not a predetermined time has passed (step S12). If the predetermined time has not elapsed (step S12: No), it is determined that the image density adjustment operation is not necessary, and the printer engine 130 determines whether there is a next page to be printed (step S13). If there is no next page (step S13: No), the process ends. On the other hand, when there is a next page (step S13: Yes), the process returns to step S11 and is repeated.

  In step S12, when the predetermined time has elapsed (step S12: Yes), it is determined that the image density adjustment operation is necessary, and the adjustment operation determination unit 203 determines that the photoconductors 4Y, 4M, and 4C and the transfer belt 1 are used. Is separated from each other (step S14). When it is determined that they are separated (step S14: Yes), the adjustment operation determination unit 203 determines that only the image density adjustment by the monochrome adjustment unit 201 is performed, and the adjustment of the image density of black (Bk) is performed. It is executed (step S16).

  On the other hand, when it is determined that they are not separated, that is, when it is determined that the photoconductors 4Y, 4M, and 4C are in contact with the transfer belt 1 (step S14: No), the adjustment operation determination unit 203 is It is determined that only the adjustment of the image density by the color adjustment unit 202 is performed, and the adjustment of the image density of yellow (Y), magenta (M), and cyan (C) is executed (step S15).

  As described above, in the printer according to the first embodiment, when the photoreceptors 4Y, 4M, and 4C and the transfer belt 1 are separated from each other, it is determined that monochrome printing is performed, and the image density of Bk is determined. If only the adjustment is performed and the photoreceptors 4Y, 4M, and 4C are in contact with the transfer belt 1, it is determined that color printing is being performed, and only the image densities of Y, M, and C are adjusted. . Therefore, as compared with the case of adjusting the image density of four colors, the image density of each of the image density adjustment of yellow, cyan and magenta (three colors) and the image density of black (one color) is adjusted. The adjustment time can be shortened, the waiting time of the user can be reduced, and convenience can be improved. In addition, when printing a monochrome image, the printer according to the first embodiment separates the photoconductors 4Y, 4M, and 4C from the transfer belt 1, so that the photoconductors 4Y, 4M, and 4C can be made long lasting. .

(Embodiment 2)
In the printer according to the first embodiment, whether the adjustment by the monochrome adjustment unit or the adjustment by the color adjustment unit is performed depending on whether the photoconductors 4Y, 4M, and 4C are separated from or in contact with the transfer belt 1. I was judging. On the other hand, in the present embodiment, it is determined whether the adjustment by the monochrome adjustment unit or the adjustment by the color adjustment unit is performed according to the setting of monochrome printing or color printing.

  The configurations of the image forming unit and the printer are the same as those in the first embodiment, and thus description thereof is omitted (see FIGS. 1 and 2). Next, the control of the entire controller executed by the controller 101 will be described. FIG. 13 is a block diagram of a functional configuration of the controller 101 in the printer 100 according to the second embodiment.

  The controller 101 mainly includes a monochrome adjustment unit 201, a color adjustment unit 202, an adjustment operation determination unit 303, and a mode setting unit 304, to which an NV-RAM 109 is connected. Here, since the functions and configurations of the monochrome adjustment unit 201, the color adjustment unit 202, and the NV-RAM 109 are the same as those in the first embodiment, description thereof will be omitted.

  The mode setting unit 304 receives a monochrome mode in which an image is formed on a recording sheet using only one color of black (Bk), yellow (Y), magenta (M), and cyan (C ), When an input instruction for setting one of the print modes, which is a color mode for forming an image on recording paper with four colors of black (Bk), is received, the received print mode is stored in the NV-RAM 109. The print mode is set.

  When the print mode setting is switched, the adjustment operation determination unit 303 determines that an image density adjustment operation is necessary, and executes only the adjustment by the monochrome adjustment unit 201 based on the color of the image formed on the recording paper. It is also determined whether or not only the adjustment by the color adjustment unit 202 is executed.

  That is, when the mode setting unit 304 sets the color mode to the monochrome mode, the adjustment operation determination unit 303 determines that only the adjustment by the monochrome adjustment unit 201 is performed because a monochrome image is printed. On the other hand, when the mode setting unit 304 sets the monochrome mode to the color mode, since a color image is printed, it is determined that only the adjustment by the color adjustment unit 202 is executed.

  Here, the image density adjustment time in the prior art and the image density adjustment time in the present embodiment are the same as those in the first embodiment, and thus the description thereof is omitted (see FIGS. 8, 10, and 11).

  Next, print processing by the printer of this embodiment will be described. FIG. 14 is a flowchart illustrating a flow of printing processing by the printer 100 according to the second embodiment.

  First, the printer engine 130 prints one color or monochrome image (step S21). Then, the adjustment operation determination unit 303 determines whether or not the print mode setting has been switched (step S22). If the print mode setting has not been switched (step S22: No), the printer engine 130 determines whether there is a next page to be printed (step S23). If there is no next page (step S23: No), the process ends. On the other hand, when there is a next page (step S23: Yes), the process returns to step S21 and is repeated.

  When the print mode setting is switched in step S22 (step S22: Yes), the adjustment operation determination unit 303 determines whether the print mode is set to the color mode (step S24). When the color mode is not set, that is, when the monochrome mode is set (step S24: No), the adjustment operation determination unit 303 determines that only the image density adjustment by the monochrome adjustment unit 201 is performed, and black ( The image density of Bk) is adjusted (step S26).

  On the other hand, when the color mode is set (step S24: Yes), the adjustment operation determination unit 303 determines that only the image density adjustment by the color adjustment unit 202 is performed, and yellow (Y), magenta (M), The cyan (C) image density is adjusted (step S25).

  As described above, when the printer according to the second embodiment is set to the monochrome mode, it is determined that monochrome printing is performed, and only the Bk image density is adjusted, and when the color mode is set. Therefore, it is determined that color printing is being performed, and only the Y, M, and C image densities are adjusted. Therefore, as compared with the case of adjusting the image density of four colors, the image density of each of the image density adjustment of yellow, cyan and magenta (three colors) and the image density of black (one color) is adjusted. The adjustment time can be shortened, the waiting time of the user can be reduced, and convenience can be improved.

(Embodiment 3)
The color adjustment pattern in the first embodiment is obtained by arranging the adjustment patterns of the respective colors (three colors) in parallel in the sub-scanning direction of the transfer belt. On the other hand, the color adjustment pattern in this embodiment arranges the adjustment patterns for each color in series in the sub-scanning direction of the transfer belt.

  Since the configuration of the image forming unit, the printer, and the functional configuration of the controller are the same as those in the first embodiment, description thereof is omitted (see FIGS. 1 to 3).

  Next, the adjustment pattern formed on the transfer belt 1 will be described. FIG. 15 is a diagram illustrating an example of a black adjustment pattern for adjusting the black (Bk) color. As shown in FIG. 15, the black adjustment pattern is an adjustment pattern in which ten black adjustment patches having different densities are arranged in a gradation from the left to the right. The black adjustment pattern is formed so that adjustment patches are arranged in the sub-scanning direction of the transfer belt 1 by the photoconductor 4Bk or the like that has received an instruction from the controller 101. When the black adjustment pattern is detected by the pattern detection sensor 2, the monochrome adjustment unit 201 measures the black image density and refers to the detected black adjustment pattern density and the image density stored in the NV-RAM 109. Then, the image density of black is adjusted by performing feedback control. The description of the feedback control method is omitted as in the first embodiment.

  FIG. 16 is a diagram illustrating an example of a color adjustment pattern for simultaneously adjusting three colors of cyan (C), magenta (M), and yellow (Y). As shown in FIG. 16, the color adjustment pattern is an adjustment pattern in which 10 adjustment patches of different colors are arranged in parallel from the left to the right. The color adjustment pattern is transferred in the sub-scanning direction of the transfer belt 1 in the order of cyan (C), magenta (M), and yellow (Y) by the photoconductors 4Y, 4M, 4C, and the like that have received instructions from the controller 101. Are formed in series. When the color detection pattern is detected by the pattern detection sensor 2, the color adjustment unit 202 measures the image density of each color (three colors), and the density of the detected color adjustment pattern and the image stored in the NV-RAM 109. The image density of yellow, cyan, and magenta is adjusted by performing feedback control with reference to the density. As with the above, description of the feedback control method is omitted.

  Next, first, adjustment time when image density adjustment in the prior art, that is, image density adjustment of all four colors of black (Bk), cyan (C), magenta (M), and yellow (Y) is performed simultaneously. Then, the monochrome and color image density adjustment time of the printer of this embodiment will be described.

  FIG. 17 is an example of a timing chart showing image density adjustment time in the prior art. In the timing charts in the following embodiments, it is assumed that the timings for forming the adjustment patterns of the respective colors are lowered by the photoreceptors 4Y, 4M, 4C, and 4Bk. Similarly, it is assumed that pattern detection by the pattern detection sensor 2 is also performed when the pattern detection sensor 2 is low.

  In a conventional printer, when a color image is printed, the image density is adjusted for all colors (here, four colors). Accordingly, as shown in FIG. 17, first, a black (Bk) adjustment pattern is formed on the transfer belt 1 by the photoreceptor 4 </ b> Bk. Then, at a predetermined timing after the formation of the black (Bk) adjustment pattern is started, a cyan (C) adjustment pattern is formed on the transfer belt 1 by the photoconductor 4C. The predetermined timing is a timing at which the formation distance of the remaining adjustment pattern formed by the photoreceptor 4Bk corresponds to the distance of the transfer belt 1 between the formation position by the photoreceptor 4Bk and the formation position by the photoreceptor 4C. . Similarly, adjustment patterns of other colors are formed in the order of magenta (M) and yellow (Y).

Here, an adjustment pattern using four colors of black (Bk), cyan (C), magenta (M), and yellow (Y) will be described. FIG. 18 is a diagram illustrating an example of an adjustment pattern in the related art. As shown in FIG. 9, in this adjustment pattern, 10 adjustment patches of different colors having different densities are arranged in series in a gradation from the left to the right. This adjustment pattern is formed so that the adjustment patches are arranged in the sub-scanning direction of the transfer belt 1 by the photoreceptors 4Y, 4M, 4C, 4Bk, and the like. When this adjustment pattern is detected by the sensor, the image density of each color is adjusted.

  Then, an adjustment pattern for each of the four colors is formed on the transfer belt 1 in the order of Bk, C, M, and Y, and after the formation of the adjustment pattern for the first color (Bk of the first color) has started, a certain time has passed. Adjustment patterns for each color are detected. This fixed time is a time (a time corresponding to a distance L1 in FIG. 1) until the transfer belt 1 reaches the detection position by the pattern detection sensor 2 from the formation position of the first color adjustment pattern. Strictly speaking, it is necessary to estimate the time for the start of charging and the start of exposure for each color, but these times are omitted in the present embodiment.

  Next, the adjustment time of the image density of yellow, cyan, and magenta by the printer of this embodiment will be described. FIG. 19 is an example of a timing chart showing adjustment times of yellow, cyan, and magenta image densities in the third embodiment.

  In the printer of this embodiment, as described above, when printing a color image, the image density is adjusted for colors other than black (here, three colors Y, M, and C). Accordingly, as shown in FIG. 19, first, a cyan (C) adjustment pattern is formed on the transfer belt 1 by the photoreceptor 4C. A magenta (M) adjustment pattern is formed on the transfer belt 1 by the photosensitive member 4M at a predetermined timing after the formation of the cyan (C) adjustment pattern is started. This predetermined timing is the same as in the prior art (see FIG. 17). Similarly, adjustment patterns are formed in the order of yellow (Y). As described above, the black (Bk) adjustment pattern is not formed.

  In this embodiment, the color adjustment patterns are formed in the order of cyan (C), magenta (M), and yellow (Y), and the color adjustment patterns are formed in the reverse order of the first embodiment. That is, as in the first embodiment, when the color adjustment patterns are formed in the order of yellow (Y), magenta (M), and cyan (C), the formation of the yellow (Y) adjustment pattern is completed, and then magenta After the formation of the (M) adjustment pattern is started and the formation of the magenta (M) adjustment pattern is completed, the formation of the cyan (C) adjustment pattern is started. On the other hand, when the color adjustment pattern is formed in the order of cyan (C), magenta (M), and yellow (Y) as in the present embodiment, formation of the adjustment pattern for cyan (C) is started. Before the formation is completed, the formation of the magenta (M) adjustment pattern is started. Then, the formation of the yellow (Y) adjustment pattern can be started before the formation of the magenta (M) adjustment pattern is completed. Therefore, in this embodiment, since there is a section in which cyan (C) and magenta (M), and magenta (M) and yellow (Y) can simultaneously form an adjustment pattern, color adjustment is performed in order from yellow (Y). Rather than forming a pattern, forming the color adjustment pattern in order from cyan (C) leads to a reduction in adjustment time.

  Then, an adjustment pattern for each of the three colors in the order of Y, M, and C is formed on the transfer belt 1, and after a predetermined time has elapsed since the formation of the adjustment pattern for the first color (C of the first color) has started, Adjustment patterns are detected. Note that the predetermined time is the same as in the prior art.

Here, compared with the timing chart of the prior art (FIG. 17), in this embodiment, since the black (Bk) adjustment pattern is not formed, the time required for completing the detection by the pattern detection sensor 2 is increased accordingly. It is getting faster. Therefore, it is possible to shorten the image density adjustment time for yellow, cyan, and magenta compared to the image density adjustment time in the prior art.

  Next, a monochrome image density adjustment time by the printer of this embodiment will be described. FIG. 20 is an example of a timing chart showing the monochrome image density adjustment time in the third embodiment.

  In the printer of this embodiment, as described above, when printing a monochrome image, the image density is adjusted only for black. Accordingly, as shown in FIG. 20, a black (Bk) adjustment pattern is formed on the transfer belt 1 by the photosensitive member 4Bk. As described above, the adjustment patterns of yellow (Y), magenta (M), and cyan (C) are not formed.

  Then, after a predetermined time has elapsed after the Bk adjustment pattern is formed, the black adjustment pattern is detected. Note that the predetermined time is the same as in the prior art.

  Here, compared with the timing chart of the prior art (FIG. 17), in the present embodiment, the adjustment pattern of yellow (Y), magenta (M), and cyan (C) is not formed, and accordingly, the pattern is accordingly increased. The time to complete the detection by the detection sensor 2 is earlier. Therefore, the monochrome image density adjustment time can be shortened compared to the image density adjustment time in the prior art. As compared with the timing chart of the image density of yellow, cyan, and magenta (FIG. 19), the adjustment of the monochrome image density is performed only for black, so the adjustment time of the monochrome image density is yellow, cyan. The magenta image density adjustment time is shorter.

  Here, since the flow of the printing process by the printer of the present embodiment is the same as that of the first embodiment, description thereof is omitted (see FIG. 12).

  As described above, in the printer according to the first embodiment, when the photoreceptors 4Y, 4M, and 4C and the transfer belt 1 are separated from each other, it is determined that monochrome printing is performed, and the image density of Bk is determined. If only the adjustment is performed and the photoreceptors 4Y, 4M, and 4C are in contact with the transfer belt 1, it is determined that color printing is being performed, and only the image densities of Y, M, and C are adjusted. . Therefore, as compared with the case of adjusting the image density of four colors, the image density of each of the image density adjustment of yellow, cyan and magenta (three colors) and the image density of black (one color) is adjusted. The adjustment time can be shortened, the waiting time of the user can be reduced, and convenience can be improved. In addition, by forming the color adjustment patterns in series, it is possible to adjust the image density by detecting the adjustment pattern of each color with a single pattern detection sensor. It becomes unnecessary and the manufacturing cost can be reduced.

  In the present embodiment, as in the first embodiment, adjustment by the monochrome adjustment unit or color adjustment is performed depending on whether the photoreceptors 4Y, 4M, and 4C and the transfer belt 1 are separated from or in contact with each other. It is determined whether to perform adjustment by the part. Further, in the present embodiment, similarly to the second embodiment, it is possible to determine whether adjustment by the monochrome adjustment unit or adjustment by the color adjustment unit is performed according to the setting of monochrome printing or color printing. ing.

  In this embodiment, the case where four colors of black (Bk), magenta (M), cyan (C), and yellow (Y) are used is described as an example. However, the present invention is not limited to this. You may comprise by increasing / decreasing quantity and kind.

2 is a configuration diagram illustrating an example of an image forming unit of the printer 100 according to the first embodiment. FIG. 2 is a diagram illustrating an example of a configuration of a printer 100. FIG. FIG. 2 is a block diagram illustrating a functional configuration of a controller 101 in the printer 100 according to the first embodiment. It is a figure which shows an example of a black adjustment pattern. It is a figure which shows an example of a color adjustment pattern. 2 is a diagram illustrating an example of an image forming unit of the printer 100 according to the first embodiment. FIG. 2 is a diagram illustrating an example of an image forming unit of the printer 100 according to the first embodiment. FIG. It is an example of the timing chart which shows the adjustment time of the image density in a prior art. It is a figure which shows an example of the adjustment pattern in a prior art. 3 is an example of a timing chart showing adjustment times of yellow, cyan, and magenta image densities in the first embodiment. 3 is an example of a timing chart showing a monochrome image density adjustment time in the first embodiment. 3 is a flowchart illustrating a flow of printing processing by the printer 100 according to the first embodiment. FIG. 4 is a block diagram illustrating a functional configuration of a controller 101 in a printer 100 according to a second embodiment. 6 is a flowchart illustrating a flow of a printing process performed by the printer according to the second embodiment. It is a figure which shows an example of a black adjustment pattern. It is a figure which shows an example of a color adjustment pattern. It is an example of the timing chart which shows the adjustment time of the image density in a prior art. It is a figure which shows an example of the adjustment pattern in a prior art. 12 is an example of a timing chart showing adjustment times of yellow, cyan, and magenta image densities in the third embodiment. 12 is an example of a timing chart showing a monochrome image density adjustment time in the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transfer belt 2 Pattern detection sensor 3 Secondary transfer part 4Y, 4M, 4C, 4Bk Photoconductor 5Y, 5M, 5C, 5Bk Transfer roller 6 Cam 7 DC brush motor 8 Fixed member 100 Printer 101 Controller 102 CPU
103 ROM
104 RAM
105 Internal bus 106 Communication control unit 107 HDD
108 engine control unit 110 medium control unit 111 UI control unit 120 operation panel 130 printer engine 140 storage medium 201 monochrome adjustment unit 202 color adjustment unit 203, 303 adjustment operation determination unit 304 mode setting unit

Claims (9)

In an image forming apparatus that forms an image by superimposing a plurality of colors,
An image carrier;
An image is formed on a recording medium through the image carrier with a predetermined image density, a black first pattern having different densities, and a second pattern having a plurality of colors other than black and having different densities. Writing means for forming the image carrier on the image carrier;
First detection means for detecting the first pattern and the second pattern formed on the image carrier;
First adjusting means for adjusting the black image density at the time of image formation based on the detected first pattern;
Based on the detected second pattern, second adjusting means for adjusting image densities of a plurality of colors other than black at the time of image formation;
Adjustment operation determining means for determining whether only the adjustment by the first adjusting means or only the adjustment by the second adjusting means is executed based on the color of the image formed on the recording medium. ,
The first adjusting means adjusts the image density of black when the first pattern is formed on the image carrier,
The image forming apparatus according to claim 2, wherein the second adjusting unit adjusts image densities of a plurality of colors other than black when the second pattern is formed on the image carrier.   2. The image forming apparatus according to claim 1, wherein the adjustment operation determination unit determines that only the adjustment by the first adjustment unit is executed during image formation using only black.   3. The image forming apparatus according to claim 2, wherein the adjustment operation determination unit determines that only the adjustment by the second adjustment unit is executed during image formation with a plurality of colors. The writing means includes first writing means for forming the first pattern on the image carrier, and second writing means for forming the second pattern on the image carrier,
A second detection means for detecting whether the second writing means and the image carrier are separated from or in contact with each other;
When the second writing unit and the image carrier are separated from each other, the adjustment operation determining unit performs only the adjustment by the first adjusting unit, and the second writing unit, the image carrier, 2. The image forming apparatus according to claim 1, wherein when the two are in contact with each other, it is determined that only the adjustment by the second adjustment unit is executed. According to an input instruction from a user, the apparatus further comprises mode setting means for setting either a monochrome mode for forming an image on the recording medium only with black or a color mode for forming an image on the recording medium with a plurality of colors.
The adjustment operation determination unit executes only the adjustment by the first adjustment unit when the monochrome mode is set, and executes only the adjustment by the second adjustment unit when the color mode is set. The image forming apparatus according to claim 1, wherein the determination is performed.   The image forming apparatus according to claim 1, wherein the writing unit forms each of the plurality of second patterns corresponding to a plurality of colors other than black in parallel in the sub-scanning direction of the image carrier. . The image forming apparatus according to claim 1, wherein the writing unit forms each of the plurality of second patterns corresponding to a plurality of colors other than black in series in the sub-scanning direction of the image carrier. .   The image forming apparatus according to claim 1, wherein an execution time of the adjustment by the first adjustment unit is shorter than an execution time of the adjustment by the second adjustment unit. In an image density adjustment method executed by an image forming apparatus that forms an image by superimposing a plurality of colors,
The image forming apparatus includes:
An image carrier;
An image is formed on a recording medium through the image carrier with a predetermined image density, a black first pattern having different densities, and a second pattern having a plurality of colors other than black and having different densities. Writing means for forming the image carrier on the image carrier;
First detection means for detecting the first pattern and the second pattern formed on the image carrier,
A first adjustment step of adjusting a black image density at the time of image formation based on the detected first pattern;
A second adjustment step of adjusting image densities of a plurality of colors other than black at the time of image formation based on the detected second pattern;
An adjustment operation determination step for determining whether to perform only the adjustment by the first adjustment step or only the adjustment by the second adjustment step, based on the color of the image formed on the recording medium;
When it is determined by the writing means that only the adjustment by the first adjustment step is executed, the first pattern is formed on the image carrier and it is determined that only the adjustment by the second adjustment step is executed. And an image forming step of forming the second pattern on the image carrier,
The first adjustment step adjusts the image density of black when the first pattern is formed on the image carrier,
In the second adjustment step, when the second pattern is formed on the image carrier, the image density of a plurality of colors other than black is adjusted.

Images