JP2005215340A - Apparatus and method for image formation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form make adjustments to image formation conditions of toner images formed on both surfaces of a transfer material and to form images of high quality over both the surfaces of the transfer material. <P>SOLUTION: The transfer material which has color patch images formed on the top and reverse surfaces passes through a specified paper conveyance path and is carried to a conveyance path 77. At this time, the color patch formed on the top surface side P1 of the transfer material is detected by a 2nd color sensor S2 and the color patch formed on the reverse surface side P2 of the transfer material is detected by a 1st color sensor S1. The color patches formed on the respective surfaces P1 and P2 of the transfer material are different in history of fixation with detection points of time. The color patches formed on the sides P1 and P2 of the transfer material are independently detected to generate color balance correction data corresponding to the fixation history of the transfer material, and then the color balance of toner images formed on both the surface sides of the transfer material can be optimized to create a color document having the both-surface images of high quality. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus and method, and more particularly, to an image forming apparatus and method for adjusting image forming conditions for providing stable high image quality.

  A plurality of electrophotographic process units having a charging device and a developing device arranged around the photosensitive member are juxtaposed in the device, and an optical image is formed on the surface of the photosensitive member in each process unit by an exposure device using laser, LED light, or the like. A latent image is formed on the surface of the photosensitive member by image formation, and the latent image is visualized using a toner by a developing device, and then sequentially transferred to the intermediate transfer belt and fixed onto the transfer material in a batch, and a color image is formed. An image forming apparatus to be formed has been put into practical use in recent years. In addition, color image forming apparatuses employing an electrophotographic system such as a color printer and a color copying machine are required to have higher output image quality.

  However, in color image forming apparatuses, the color of the resulting image changes if there are changes in the environment due to environmental changes or long-term use, especially in the case of electrophotographic color image forming apparatuses. However, there is a risk of color fluctuations and loss of color balance. For this reason, conventionally, a method for stably reproducing the color and the gradation of the color has been proposed. For example, the absolute humidity measured by the temperature / humidity sensor for each color toner using several kinds of exposure amounts according to absolute humidity, process conditions such as development bias, and gradation correction methods such as a look-up table (LUT). Based on the above, the process condition at that time and the optimum value for gradation correction are selected.

  In addition, a density detection toner patch is formed on the intermediate transfer member, the photosensitive member, etc. for each color toner so that a constant color and color gradation can be obtained even if the state of each part of the apparatus changes. The density of the unfixed single-color toner patch is detected by a density detection sensor for unfixed toner (hereinafter referred to as a density sensor). Based on the detection result, process conditions such as exposure amount and development bias, and gradation correction means such as LUT Thus, a stable color and color gradation are obtained by performing density control by applying feedback to the above. However, density control using such a density sensor detects patches by forming a patch on an intermediate transfer member or drum, and changes in the color balance of the image due to subsequent transfer and fixing to a transfer material. There is no control over. The color balance also changes depending on the transfer efficiency in transferring the toner image to the transfer material, and heating and pressurization by fixing. This change cannot be dealt with by density control using the density sensor.

  Therefore, cyan (C), magenta (M), yellow (Y), and black (K) single-color gradation patches or C, M, and Y mixed-color patches are formed on the transfer material, and the fixing material is fixed on the transfer material after fixing. A color image forming apparatus provided with a sensor (hereinafter referred to as a color sensor) for detecting the density or chromaticity of a patch has been proposed (for example, see Patent Document 1).

JP 2003-084532 A

  However, when test patches (density patches and chromaticity patches) for reading with a color sensor are formed on both surfaces of a transfer material and read with a color sensor to adjust image forming conditions, the following problems may occur. .

  When color images are formed on both sides of a transfer material, an image is formed on the surface of the transfer material 1 through a so-called electrophotographic image forming process, and then heat and pressure are applied to the toner image by a fixing device. After fixing the toner image on the upper surface, a desired color image is fixed on the second surface of the transfer material on the second surface of the transfer material through a similar image forming process. As a result, color images are formed on both sides of the transfer material.

  That is, the first toner image formed first must not only pass through the fixing device when fixing the image of itself, but must also pass through the fixing device when fixing the image on the second surface. The first image passes through the fixing device twice. Further, the toner image on the second surface on the transfer material forms an image on the transfer material that has passed the fixing device once, and then passes the fixing device once on the transfer material so that the toner image is transferred onto the transfer material 2 surface. Will be held.

  Then, even though the second image on the transfer material is formed on the transfer material that has passed through the fixing, color correction is performed when an image is formed and fixed on the first transfer material before fixing. As a result, a deviation from the proper color balance value occurs as in the first image. This is because it is known that the toner image on the transfer material has different surface properties (gloss, flatness, roughness, etc.) depending on the history of heat and pressure received. This is because, even if the toner image is formed on the front and back surfaces of the transfer material, the visible toner image varies depending on the number of times of fixing. In other words, when color correction is applied to image formation on both sides of a transfer material by the same configuration method as color correction effective for current image formation on only one side, the color correction value on each side may not be appropriate. At the same time, there is a problem that the color balance is different between the first and second images subjected to color correction.

  The present invention has been made in view of such problems, and an object thereof is to provide an image forming apparatus and method capable of adjusting optimum image forming conditions for each surface even when performing double-sided image formation. And

  In order to achieve such an object, the image forming apparatus of the present invention includes a double-sided forming unit that forms an image on the first surface and the second side of the transfer material, and the double-sided forming unit forms an image on the transfer material. Before performing, pattern forming means for forming an image of a predetermined pattern on the first surface and the second surface, and first pattern information read by reading the pattern formed on the first surface is stored. A first reading means for reading, a second reading means for reading the pattern formed on the second surface and storing the read second pattern information, and a double-side forming means for forming an image on the transfer material. The image forming conditions are adjusted using the stored first pattern information when forming an image on the first surface, and the stored second pattern information is used when forming an image on the second surface. Image forming conditions to adjust image forming conditions Characterized in that an adjusting means.

  In addition, the image forming method of the present invention includes a double-sided forming step of forming an image on the first surface and the second surface of the transfer material by the double-sided forming unit, and before forming an image on the transfer material in the double-sided forming step. A pattern forming step for performing image formation of a predetermined pattern on the first surface and the second surface in advance, and a first reading unit that reads and reads the pattern formed on the first surface. A first reading step for storing pattern information; a second reading step for storing second pattern information read by reading a pattern formed on the second surface by the second reading means; When forming an image on a transfer material in the forming step, when forming an image on the first surface, the image forming conditions are adjusted using the stored first pattern information, and when forming an image on the second surface. Record Using the second pattern information which is characterized in that an image forming condition adjusting step of adjusting an image forming condition.

  According to the present invention, before the image is formed on the transfer material by the double-side forming means, the pattern forming means for forming an image of a predetermined pattern on the first surface and the second surface in advance is formed on the first surface. A first reading means for reading the read pattern and storing the first pattern information read, and a second reading for storing the second pattern information read by reading the pattern formed on the second surface When the image is formed on the transfer material by the image forming means and the double-side forming means, when the image is formed on the first surface, the image forming conditions are adjusted using the stored first pattern information, and the image is formed on the second surface. The image forming condition adjustment unit that adjusts the image forming condition using the stored second pattern information when forming the image forming condition can be adjusted for each side of the transfer material. As a result, both sides of the transfer material It is possible to form a glide height quality image.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
Hereinafter, an embodiment in which the present invention is applied to an image recording apparatus will be described.
FIG. 1 is a cross-sectional view showing the configuration of the color LBP, and a specific operation function will be described using this. Such printer operation modes include a normal print mode and a test mode. First, the operation in the normal print mode will be described.

  The LBP in FIG. 1 is a four-drum full-color LBP. The photosensitive drums 50Y, 50M, 50C, and 50K are provided in each image forming station provided with developing materials (toners) of yellow, magenta, cyan, and black, respectively. It has been. The surface of each photosensitive drum 50Y, 50M, 50C, 50K is exposed to laser light emitted from the corresponding laser device 51Y, 51M, 51C, 51K based on the image data input from the image input unit 101. As a result, a latent image is formed, and further developed with each color developer of yellow, magenta, cyan, and black to form a toner image. On the intermediate transfer belt 52, the toner images for the respective colors formed by the photosensitive drums 50Y, 50M, 50C, and 50K are primarily transferred. A sheet P, which is a transfer material, is stacked on the sheet feeding cassette 53, is fed by a sheet feeding roller 54, is conveyed by a feed / retard roller pair 55, and a pair of conveying rollers 56, 57, and is stopped from driving. It is conveyed to the roller pair 59.

  When paper feeding from a multi paper feeding unit (not shown) is designated, sheets P as a transfer material are stacked on a multi paper feeding tray (not shown), and a multi paper feeding roller (see FIG. (Not shown) and conveyed to a pair of registration rollers 59 which is conveyed by a conveyance roller pair 57 and stopped driving. The skew of the sheet P is corrected by the registration roller pair 59, and then conveyed to the secondary transfer unit 60 at a predetermined timing to transfer the toner image on the intermediate transfer belt 52, and then the secondary transfer device 60. The toner image is fixed by being conveyed to the fixing device 61 by the secondary transfer roller 60a and the intermediate transfer belt 52.

  When FD paper discharge is specified with the image forming surface down, the sheet P that has passed through the fixing device 61 is moved by moving the flapper 67 to a position indicated by a solid line by a solenoid driven by the control unit 100. The paper passes through the upper side of the flapper 67, is conveyed to the paper discharge roller pair 62, and is conveyed to the conveyance path 77. The sheet P conveyed to the conveyance path 77 is conveyed by a pair of discharge rollers 68 and 63 and discharged and stacked on the discharge tray 64 with the image forming surface facing down.

  In addition, when FU paper discharge is specified with the image forming surface facing upward, the sheet P that has passed through the fixing device 61 is moved by moving the flapper 67 to a position indicated by a broken line by a solenoid driven by the control unit 100. Passes through the lower side of the flapper 67, is conveyed by the pair of paper discharge rollers 65, and is discharged and stacked on the paper discharge tray 66 with the image forming surface facing up. Subsequently, when an image is formed on the back surface of the sheet P, the flapper 69 is operated by a solenoid driven by the control unit 100, and the conveying direction of the sheet material P using the reverse roller pair 71 via the conveying roller pair 70. Is reversed, and the flapper 72 is operated to guide it to the duplex conveyance path 73. The sheet material P is conveyed again to the registration roller pair 59 via the conveyance roller pair 57 using the double-sided conveyance roller pairs 74, 75 and 76, and after the skew feeding is corrected, the secondary transfer is performed at a predetermined timing. The toner image on the intermediate transfer belt 52 is transferred to the back surface of the sheet P by being conveyed to the unit 60. Next, the secondary transfer roller 60a of the secondary transfer device 60 and the intermediate transfer belt 52 are conveyed to the fixing device 61 to fix the toner image on the back surface of the sheet P, and are conveyed to the paper discharge tray 64 or 66. The paper is ejected.

  FIG. 2 is a diagram showing an example of the patch pattern 82 formed on the sheet P. As shown in FIG. The patch pattern 82 for density or chromaticity control is a gray tone patch pattern that is the center of the color reproduction area and is a very important color for achieving color balance. It is composed of a gray gradation patch 80 only for black (K) and a process gray gradation patch 81 in which yellow (Y), magenta (M), and cyan (C) are mixed, and patches 80a and 81a, patch 80b, As in 81b and patches 80c and 81c, in the standard image forming apparatus, only the gray (K) gray gradation patch 80 and the process gray gradation patch 81 having the same or the closest chromaticity are arranged in pairs.

  FIG. 3 is a cross-sectional view showing details of the conveyance path 77 and the color sensors S1 and S2 in the color LBP. The color sensors S1 and S2 are arranged on the conveyance path 77 so as to be able to detect different surfaces of the sheet P. The color sensor S1 sequentially applies patches 82 formed on the P1 side which is the back surface on the sheet P from the patch 80a. Then, the color sensor S2 sequentially detects patches 82 formed on the P2 side, which is the surface on the sheet P, from the patch 80a.

Next, the operation in the test mode will be described with reference to the flowchart of FIG.
In step S401, the control unit 100 determines whether or not a print command is received from the image input unit 101. If the print command is received, the control unit 100 proceeds to step S402.

  In step S402, the control unit 100 determines whether the print command received from the image input unit 101 indicates the normal print mode or the test mode. If the print command is the normal print mode, the control unit 100 determines that the print command is the sheet P in step S403. The toner image forming operation is started. On the other hand, if it is the test mode, the process proceeds to step S404, and image formation of the test pattern (patch pattern 82) on the front surface P1 of the sheet P is started. The test mode is specified when the test mode is specified with an operation panel (not shown) on the printer or an external device such as a personal computer connected to the printer, or when the control unit 100 changes the environment. This is a case where it is necessary to automatically perform the test mode based on the detection result of the variation of each part of the apparatus.

  In step S404, the control unit 100 starts to form a toner image on the surface P1 of the sheet P. Specifically, the control unit 100 generates a test pattern (patch) signal from a signal generation circuit (not shown), and the test pattern (patch). The surfaces of the photosensitive drums 50Y, 50M, 50C, and 50K are exposed by laser light emitted based on the signal data to form latent images. Thereafter, a test pattern toner image is formed on the sheet P by the same process as the operation in the normal print mode and is conveyed to the fixing device 61 to fix the toner image.

  In step S405, the control unit 100 reverses the sheet P so that the test pattern is formed on the back surface P2 of the sheet P. Specifically, the sheet P that has passed through the fixing device 61 is transported to the double-sided transport path 73 by switching the transport direction by the reverse roller pair 71, and the sheet P is transported to the position of the registration roller pair 59. .

  In step S406, the control unit 100 starts to form a toner image on the back surface P2 of the sheet P. Specifically, the control unit 100 generates a test pattern (patch) signal from a signal generation circuit (not shown), and the test pattern (patch). The surfaces of the photosensitive drums 50Y, 50M, 50C, and 50K are exposed by laser light emitted based on the signal data to form latent images. Thereafter, a test pattern toner image is formed on the sheet P by the same process as the operation in the normal print mode and is conveyed to the fixing device 61 to fix the toner image.

  In step S <b> 407, the control unit 100 performs chromaticity inspection of the sheet P using the color sensors S <b> 1 and S <b> 2 provided on both sides of the conveyance surface of the conveyance path 77. Specifically, the front surface P1 of the sheet P is detected by the color sensor S2, and the back surface P2 of the sheet P is detected by the color sensor S1. The result of detecting the front surface P1 of the sheet P by the color sensor S2 is used to adjust the image forming conditions for the first surface when performing double-sided printing, and the back surface P2 of the sheet P is detected by the color sensor S1. The result is used to adjust the image forming conditions for the second side when performing duplex printing.

  In step S408, the control unit 100 sets image forming conditions in the normal print mode. As the setting of the image forming conditions, the control unit 100 uses the detected result of the exposure amount by the laser device 51 of the image forming unit and the developing roller facing the photosensitive drum 50 to develop the photosensitive drum 50 with a toner image. To a table (calibration table) for correction processing performed by the image input unit 101 on an input image from an external device in order to correct the process conditions such as the developing bias voltage applied to the image and the density-gradation characteristics. By feeding back, the density or chromaticity of the final output image formed on the transfer material is controlled. Although it is possible to detect the output image of the color image forming apparatus with an external image reading device or a densitometer / chromaticity meter and perform the same control, this method completes the control within the color image forming apparatus. Is excellent. This color sensor uses, for example, three or more light sources having different emission spectra such as red (R), green (G), and blue (B) as light emitting elements, or the light emitting elements emit light of white (W). Are used to provide three or more types of filters having different spectral transmittances such as red (R), green (G), and blue (B) on the light receiving element. As a result, three or more different outputs such as RGB output can be obtained.

  Finally, in step S409, the control unit 100 determines whether or not the sheet P is discharged from the color LBP and stacked on the discharge tray 64. If it is determined that the sheet P is discharged, the operation on the sheet P is ended. . The color sensors S1 and S2 do not need to be opposed to each other, and may be located anywhere as long as the color sensors S1 and S2 are installed on the respective surfaces of the transfer material conveyed after fixing and satisfy the functions thereof.

(Second Embodiment)
In the first embodiment, the image recording apparatus is a color image forming apparatus using a so-called intermediate transfer belt. However, as another embodiment of the present invention, a so-called transfer conveyance belt that performs direct transfer while conveying on a transfer material. A color image forming apparatus using can be used.

It is sectional drawing which shows the structure of the color LBP concerning one Embodiment of this invention. It is a figure which shows an example of the patch pattern formed on the conventional sheet | seat P. FIG. It is sectional drawing which shows the detail of a conveyance path, a 1st color sensor, and a 2nd color sensor among color LBP. It is a flowchart which shows operation | movement of color LBP.

Explanation of symbols

50Y, 50M, 50C, 50K Photosensitive drums 51Y, 51M, 51C, 51K Laser device 52 Intermediate transfer belt 53 Paper feed cassette 54 Paper feed roller 55 Feed / retard rollers 56, 57, 70 Transport roller pair 59 Registration roller pair 60 Secondary Transfer section 60a Secondary transfer roller 61 Fixing device 62, 63, 65, 68 Paper discharge roller pair 64, 66 Paper discharge tray 67, 69, 72 Flapper 71 Reverse roller pair 73 Double-sided conveyance path 74-76 Double-sided conveyance roller pair 77 Path 80, 81, 82 Patch 100 Control unit 101 Image data input unit S1, S2 Color sensor

Claims (8)

An image forming apparatus comprising double-sided forming means for forming an image on a first surface and a second surface of a transfer material,
Pattern forming means for forming an image of a predetermined pattern on the first surface and the second surface in advance before forming an image on the transfer material by the double-side forming means;
First reading means for reading a pattern formed on the first surface and storing the read first pattern information;
Second reading means for reading the pattern formed on the second surface and storing the read second pattern information;
When forming an image on the transfer material by the double-sided forming means, when forming an image on the first surface, the second surface is adjusted by adjusting image forming conditions using the stored first pattern information. An image forming apparatus comprising: an image forming condition adjusting unit that adjusts an image forming condition using the stored second pattern information when forming an image. The double-sided forming unit sequentially forms an image using an exposure apparatus and an electrophotographic process unit, and applies predetermined heat and pressure to the toner image on the first surface of the transfer material to thereby transfer the transfer material. After the image forming process for fixing the toner image on the first surface is performed, the image forming process is performed on the second surface of the transfer material to thereby form the first surface and the second surface of the transfer material. Image formation on the surface,
The predetermined pattern is a color patch,
The pattern information is the density or chromaticity of the color patch formed on the transfer material, and the image forming condition adjusting means adjusts the density or chromaticity unevenness when forming an image on the transfer material. The image forming apparatus according to claim 1.   The double-sided forming means sequentially forms a primary transfer image on an intermediate transfer belt using an exposure apparatus and an electrophotographic process unit, and after the secondary transfer of the primary transfer image onto the transfer material in a batch, the transfer material 2. An image is formed on a first surface and a second surface of the transfer material by fixing the toner image to the transfer material by applying predetermined heat and pressure to the upper toner image. The image forming apparatus described in 1.   The double-side forming unit sequentially transfers multiple images onto the transfer material while conveying the transfer material by a transfer conveyance belt using an exposure apparatus and an electrophotographic process unit, and then applies a predetermined image to the toner image on the transfer material. 2. The image forming apparatus according to claim 1, wherein an image is formed on the first surface and the second surface of the transfer material by fixing the toner image to the transfer material by applying heat and pressure. .   The double-sided forming unit sequentially transfers images onto the belt in a multiplex manner with a photosensitive belt using an exposure apparatus and an electrophotographic process unit, and then transfers the primary transfer image collectively onto the transfer material. The image formation is performed on the first surface and the second surface of the transfer material by fixing the toner image to the transfer material by applying predetermined heat and pressure to the toner image on the transfer material. The image forming apparatus according to claim 1. The first reading unit reads a pattern formed on the first surface after fixing the first surface of the transfer material N times, and stores the read first pattern information.
The second reading unit reads a pattern formed on the second surface after fixing the second surface of the transfer material N-1 times and stores the read second pattern information. The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus. An instruction input means for inputting an instruction as to whether or not to adjust the image forming conditions;
6. The image forming apparatus according to claim 1, wherein the image forming condition adjusting unit does not adjust the image forming condition when the instruction indicates that the adjustment is not performed. An image forming method comprising a double-sided forming step of forming an image on a first surface and a second surface of a transfer material by a double-sided forming unit,
A pattern forming step of performing image formation of a predetermined pattern on the first surface and the second surface in advance before forming an image on the transfer material in the double-sided formation step;
A first reading step of reading a pattern formed on the first surface by a first reading unit and storing the read first pattern information;
A second reading step of reading the pattern formed on the second surface by the second reading means and storing the read second pattern information;
In forming an image on the transfer material in the double-sided forming step, when forming an image on the first surface, the second surface is adjusted by adjusting image forming conditions using the stored first pattern information. An image forming method comprising: an image forming condition adjusting step for adjusting an image forming condition using the stored second pattern information when forming an image.

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