JP2018141859A - Writing control device and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a writing control device which reduces the downtime due to color shift correction regardless of the formation position of a correction pattern.SOLUTION: An optical writing control unit 409 includes: a light emission control section 34 which controls light emission of an LEDA 11; a correction pattern generation section 32 which can generate the first correction pattern group formed of the transverse line and the second correction pattern group formed of the slant line; a correction value calculation section 36 which calculates the correction value of correcting the writing position on a photoreceptor on the basis of the detection result of correction pattern detection means 17 of detecting a correction pattern image in an endless rotor; and a correction execution determination section 31 which receives the result of fluctuation factor detection means 500 that can detect the change of the state of an apparatus mounted with the optical writing control device and determines the necessity of correction execution using the correction pattern. The correction pattern generation section selects a case of generating both of the first correction pattern group and the second correction pattern group or a case of generating only the first correction pattern group.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a writing control apparatus and an image forming apparatus.

  In an image forming apparatus using a binary LEDA (Light-emitting diode Array) writing method, image adjustment such as color misregistration correction and density correction for a formed image is performed by forming a test pattern on the intermediate transfer belt, It is already known to perform this test pattern (correction pattern) by detecting it with a sensor.

  In addition, there is a high possibility that color misregistration will occur in the state of the device immediately after the power is turned on, such as when the main power is turned on or after returning from the sleep mode, so during the first printing operation immediately after the power is turned on or immediately after the power is turned on. It is already known to perform color misregistration correction.

  When the power is turned on, if the reserved print job is monochrome output, the print job is executed without image adjustment. If the reserved print job is color output, the print job is executed after image adjustment. It is already known that the start-up time can be shortened during monochrome output and the adjusted image can be output during color output.

  Patent Document 1 discloses a first test pattern sequence that is arranged at a position that does not overlap a print image for the purpose of reducing downtime immediately after power-on while maintaining image quality, and a print image. In a system in which color misregistration correction is performed using the second test pattern sequence arranged at the overlapping position, if there is a print request during execution of color misregistration correction after the power is turned on, the formation of the second test pattern sequence is stopped. Thus, it is disclosed that color misregistration correction is continued using only the first test pattern sequence.

  However, in the above-mentioned Patent Document 1, there is a condition that both the first test pattern row arranged at a position not overlapping with the print image and the second test pattern row arranged at a position overlapping the print image can be formed. There is a problem that downtime can be reduced only by the connected color misregistration correction system.

  Therefore, in view of the above circumstances, an object of the present invention is to provide a writing control apparatus that can reduce downtime due to color misregistration correction while maintaining image quality regardless of the position where the correction pattern is formed.

In order to solve the above problems, in one embodiment of the present invention,
An optical writing control device that controls an exposure unit including an LED light source that exposes a rotatable photosensitive member to write an electrostatic latent image,
A light emission control unit that controls light emission of the LED light source based on information of pixels or correction patterns constituting an image to be imaged and output;
A correction pattern generation unit capable of generating a first correction pattern group consisting of horizontal lines and a second correction pattern group consisting of diagonal lines as the correction patterns, and sending the correction patterns to the light emission control unit;
The correction pattern image by the correction pattern detection means for detecting the correction pattern image on the endless rotating body on which the correction pattern image developed by developing the electrostatic latent image of the correction pattern formed on the photosensitive member is transferred and conveyed. A correction value calculation unit that calculates a correction value for correcting the writing position on the photoconductor by the LED light source controlled by the light emission control unit, based on the detection result of
Correction execution for determining whether or not correction execution using the correction pattern is necessary by inputting a detection result of a variation factor detecting means capable of detecting a change when a change occurs in the state of the apparatus on which the optical writing control apparatus is mounted. A determination unit, and
The correction pattern generation unit generates the correction pattern using both the first correction pattern group and the second correction pattern group according to the result of the variation factor detection unit; and There is provided an optical writing control device capable of selecting a case where the correction pattern is generated using only a correction pattern group.

  According to one aspect, in the writing control apparatus, it is possible to reduce downtime due to color misregistration correction while maintaining image quality regardless of the position where the correction pattern is formed.

1 is a diagram illustrating an example of the overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 6 is a diagram showing another example of the overall configuration of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a diagram illustrating functional blocks of the image forming apparatus according to the embodiment of the invention. 1 is a hardware block diagram of an image forming apparatus according to an embodiment of the present invention. The control block diagram of the write-control apparatus which concerns on embodiment of this invention. Explanatory drawing of main scanning color shift comparison of LD writing and LED writing. Explanatory drawing of the correction pattern image formed on a conveyance path | route. FIG. 6 is a diagram for explaining color misregistration detection in the main scanning direction and sub-scanning direction using a color misregistration detection pattern. The figure explaining the horizontal line pattern specialized in the color shift correction | amendment of a subscanning direction. Explanatory drawing of color misregistration correction execution judgment which concerns on this invention. 9 is a flowchart of color misregistration correction execution determination according to a comparative example.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the following drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

<Overall configuration of image forming apparatus>
FIG. 1 is a diagram illustrating an example of an embodiment of an image forming apparatus 100 according to the present embodiment. The image forming apparatus 100 shown in the figure transfers an image by a direct transfer method.

  The image forming apparatus 100 includes a sheet feeding and conveying unit such as a sheet feeding tray 1, a conveying and transferring unit including a conveying belt 5, a transfer device 15, pattern detection sensors 17 and 18, an image forming unit 6, and a fixing device 16. Have

  The conveyor belt 5 is an endless rotating body that moves a sheet P that is an example of a recording medium. The conveyor belt 5 is wound around a driving roller 7 that is driven to rotate and a driven roller 8. The drive roller 7 is driven to rotate by a drive motor (not shown). The driving roller 7 and the driven roller 8 move the conveyance belt 5.

  The paper feed tray 1 stores paper P. The paper P is separated one by one by the paper feed roller 2 and the separation roller 3, transported while being guided by the guide plate 4, and transported by the transport belt 5 from the upstream side in the transport direction of the transport belt 5. The paper P is attracted to the transport belt 5 by an electrostatic attraction action.

  From the upstream side of the conveying belt 5, an image forming unit 6BK for black, an image forming unit 6M for magenta, an image forming unit 6C for cyan, and an image forming unit 6Y for yellow are arranged. The configuration of the image forming unit 6 is different in the color of the toner image to be formed, but the internal configuration is the same.

  The paper P is first transported to the image forming unit 6BK and transferred with a black toner image. Similarly, on the paper P, a magenta toner image, a cyan toner image, and a yellow toner image are transferred.

  The image forming unit (image unit) 6BK includes a photosensitive drum 9BK, a charger 10BK, a solid-state scanning head 11BK, a phenomenon unit 12BK, a photosensitive member cleaner (not shown), a grading unit 13BK, and the like. The image forming unit 6BK can be replaced as a photoconductor unit (PCDU: Photo Conductor Drum Unit) when the image forming unit 6BK deteriorates due to aging.

  The photoreceptor drum 9BK is a photoreceptor that transfers toner onto the paper P. Around the photoconductor drum 9BK, a charger 10BK, a solid scanning head 11BK, a phenomenon device 12BK, a photoconductor cleaner (not shown), a slow charger 13BK, and the like are arranged.

  The charger 10BK uniformly charges the outer peripheral surface of the photosensitive drum 9BK in the dark.

  The solid-state scanning head 11BK includes an LED light source (LED array 63, see FIG. 6) that is a light emitting element such as a plurality of LEDs. The solid scanning head 11BK functions as an exposure unit that emits light corresponding to the black image and forms a latent image of the black image on the photosensitive drum 9BK.

  The phenomenon device 12BK uses black toner to visualize the latent image of the black image formed on the photosensitive drum 9BK, that is, forms a black toner image on the photosensitive drum 9BK.

  The transfer unit 15BK transfers the black toner image at a transfer position where the photosensitive drum 9BK and the paper P on the transport belt 5 are in contact with each other.

  After the black toner image is transferred to the paper P, the photoconductor cleaner wipes off unnecessary toner remaining on the outer peripheral surface of the photoconductor drum 9BK, and the gradual charger 13BK neutralizes the photoconductor drum 9BK.

  After the black toner image is transferred, the paper P is transported to the next image forming unit 6M by the transport belt 5.

  Similar to the procedure in the image forming unit 6BK, the image forming unit 6M forms a magenta toner image on the photosensitive drum 9M, and transfers the magenta toner image superimposed on the black toner image on the paper P. .

  Similarly, in the image forming unit 6C and the image forming unit 6Y, the cyan toner image and the yellow toner image are transferred to the paper P.

  Note that the configurations of the image forming unit 6M, the image forming unit 6C, and the image forming unit 6Y are the same as the functions of the image forming unit 6BK.

  Four color toner images are transferred to the paper P, and a full color image is formed on the paper P.

  The paper P on which the full-color image is formed is peeled off from the transport belt 5 and sent to the fixing device 16. The fixing device 16 fixes the full-color image on the paper P, and then discharges it to the outside of the image forming apparatus 100.

  The image forming apparatus 100 includes pattern detection sensors 17 and 18. The pattern detection sensors 17 and 18 are optical sensors for reading the misregistration correction pattern and the density correction pattern transferred onto the conveyance belt 5 by the photosensitive drums 9BK, 9M, 9C, and 9Y.

  The pattern detection sensors (correction pattern detection means) 17 and 18 receive the reflected light from the light emitting element for irradiating the pattern drawn on the surface of the conveyor belt (endless rotating body) 5 and the correction pattern. Includes a light receiving element.

  The belt cleaner 20 is disposed downstream of the pattern detection sensors 17 and 18 and upstream of the photosensitive drum 9. The belt cleaner 20 scrapes off the toner adhering to the surface of the conveyor belt 5.

  FIG. 2 shows another example of the overall configuration of the image forming apparatus according to the embodiment of the present invention. In this example, the description of the parts common to FIG. 1 is omitted, and different parts will be described. The image forming apparatus 100A shown in FIG. 2 transfers an image by an intermediate transfer method.

  The image forming apparatus 100 </ b> A includes a paper feed conveyance unit such as a paper feed tray 1, an intermediate transfer belt 19, a conveyance transfer unit including a primary transfer unit 23, pattern detection sensors 17 and 18, an image formation unit 6, And a fixing device 16A.

  In the image forming apparatus 100A of FIG. 2, the conveyance belt 5 that conveys the paper P so as to directly transfer the toner image from the photosensitive drum 9 to the paper P is not an endless rotating body, and the toner image is temporarily formed on the outer circumferential surface of the belt. The intermediate transfer belt 19 to be held is used as an endless rotating body.

  The image forming unit 6 provided for each color forms a toner image on the photosensitive drum 9 for each color, as in FIG.

  The toner image formed on the photosensitive drum 9BK is sandwiched between the photosensitive drum 9BK and the primary transfer unit 23BK, and the black toner image is transferred to the intermediate transfer belt 19. The photosensitive drums 9M, 9C, and 9Y on which the toner images of different colors are formed sandwich the toner images together with the primary transfer units 23M, 23C, and 23Y, and thereby the black toner images of the rotating intermediate transfer belt 19 are sandwiched. A toner image is transferred on top of the toner image. By this transfer, a full-color image is formed on the intermediate transfer belt 19.

  The full-color image formed on the intermediate transfer belt 19 is transferred to the paper P at the secondary transfer nip 21. In the secondary transfer nip 21, the sheet P is pressed against the intermediate transfer belt 19 by sandwiching the sheet P between the secondary transfer roller 22 and the driven roller (secondary transfer counter roller) 8 </ b> A. Thereby, transfer efficiency can be improved.

  After the full-color image is transferred to the paper P, the fixing device 16A fixes the full-color image on the paper P. After the fixing, the fixing device 16A discharges the paper P to the outside of the image forming apparatus 100A.

  In the following description, an example of the image forming apparatus 100 will be described. However, the configuration and control described below are also applicable to the image forming apparatus 100A shown in FIG.

<Functional configuration>
FIG. 3 is a diagram illustrating an example of a functional configuration of the image forming apparatus 100 according to the present embodiment.

  The image forming apparatus 100 includes a control unit 401, a computer interface unit 402, an image forming process unit 403, a print request receiving unit 404, an operation unit 405, a print job management unit 406, a fixing unit 407, and a reading unit. 408, an image writing control unit 409, a line memory 410, an optical writing unit 411, and a storage unit 412.

  The control unit 401 controls each of these blocks.

  The computer interface unit 402 relays signals transmitted and received between a terminal such as a computer and the image forming apparatus 100.

  The print request reception unit 404 receives a print request from the terminal via the computer interface unit 402, and requests the control unit 401 for request processing and image data.

  A print job management unit 406 manages the order of print requests received by the image forming apparatus 100. Further, as shown in FIG. 5 described later, it has a function of counting the number of printed sheets (printed pages).

  The image forming process unit 403 creates a toner image on the photosensitive drum 9 by electrophotography in cooperation with the optical writing control unit 409 and transfers the toner image onto the paper P. This corresponds to the image forming unit including the photosensitive drum 9, the chargers 10 and 13, the developing device 12, the slow electric machine 13 and the like shown in FIGS. In addition, when a positional deviation or the like is detected during printing, the image forming process unit 403 performs correction as appropriate.

  The fixing unit 407 (16) applies heat and pressure to the paper P on which the toner image is transferred to fix the toner image.

  The operation unit 405 receives an operation input from the user to the image forming apparatus 100 and notifies the control unit 432 of the received input content. The operation unit 405 displays the state of the image forming apparatus 100 to the user. Further, as shown in FIG. 5 to be described later, switching of the power mode (power ON / OFF, energy saving mode, standby mode, drive mode) is instructed by the user.

  When the image forming apparatus 100 is used as a copying machine, the reading unit 408 reads, for example, an image (printing information) of a document on a document tray or contact glass, converts it into image data (electrical signal), and performs control. To the unit 401.

  The storage unit 412 stores information necessary for the image forming apparatus 100 to operate. Image data is received from the terminal and the reading unit 408 and stored. A control log of the control unit 401 to the optical writing control unit 409 is stored.

  The optical writing control unit 409 performs image processing on the image data transmitted from the print request receiving unit 404 or the reading unit 408, converts the image data into a solid scanning head control signal, and turns on the solid scanning head 11. Specifically, the optical writing control unit 409 causes the solid-state scanning head 11 to emit light in order to form a latent image corresponding to the generated pixel data on the photosensitive drum 9. A light emission processing method of the optical writing control unit 409 and the solid-state scanning head 11 will be described later with reference to FIG.

  The line memory 410 serves as a memory for the optical writing control unit 409, stores image data transmitted from the print request reception unit 404 or the reading unit 408 via the control unit 401 in a temporary buffer, and performs skewing by image processing. Adjust the amount.

<Hardware configuration>
FIG. 4 is a diagram illustrating an example of a hardware configuration of the image forming apparatus 100 according to the present embodiment. The image forming apparatus 100 according to the present embodiment includes an engine 113 that executes image formation in addition to the same configuration as an information processing terminal such as a general server or a PC (Personal Computer).

  As shown in FIG. 4, the image forming apparatus 100 according to the present embodiment includes a CPU (Central Processing Unit) 110, a RAM (Random Access Memory) 111, a ROM (Read Only Memory) 112, an engine 113, an HDD (Hard Disk Drive). ) 114 and I / F (Interface) 115 are connected via a bus 118.

  An LCD (Liquid Crystal Display) 116 and an operation unit 117 are connected to the I / F 115.

  The CPU 110 is a calculation unit and controls the operation of the entire image forming apparatus 100. The RAM 111 is a volatile storage medium that can read and write information at high speed. When the CPU 110 processes information, the RAM 111 is used as a work area for the CPU 110. The ROM 112 is a read-only nonvolatile storage medium and stores a program such as firmware.

  The engine 113 is a mechanism that actually executes image formation in the image forming apparatus 100. For example, the image forming unit 6, a toner replenishing mechanism that replenishes toner from the toner bottle (not shown) to the developing device 12, a paper feed / conveying mechanism (2, 3), a transfer unit (15, 8, 23, 22, 19) and a drive control unit such as the fixing unit 16 or the like.

  The HDD 114 is a non-volatile storage medium that can read and write information, and stores an OS (Operating System), various control programs, application programs, and the like.

  The I / F 115 connects and controls the bus 118 and various hardware and networks.

  The LCD 116 is a visual user interface for the user to check the state of the image forming apparatus 100. The operation unit 117 includes a user interface such as a keyboard and a mouse for the user to input information to the image forming apparatus 100.

  In such a hardware configuration, a program stored in a recording medium such as the ROM 112, the HDD 114, or an optical disk (not shown) is read into the RAM 111. A software control unit is configured by the CPU 110 performing calculations according to the program read into the RAM 111. A functional block as shown in FIGS. 3 and 5 for realizing the functions of the image forming apparatus 100 according to the present embodiment is configured by a combination of the software control unit configured as described above and hardware.

<Functional configuration of optical writing controller>
Next, a control block of the optical writing control unit 409 according to the present embodiment will be described with reference to FIG. FIG. 5 is a diagram illustrating a functional configuration of the optical writing control unit (optical writing control device) 409 according to the present embodiment, and a connection relationship between the LEDA 11 and the pattern detection sensors 17 and 18 and the variation factor detection unit.

  As shown in FIG. 5, the optical writing control unit 409 according to the present embodiment includes a light emission control unit 34, a counting unit 35, a correction value calculation unit 36, a sensor control unit 37, a reference value storage unit 38, and a correction value storage unit 39. including.

  Further, the optical writing control unit 409 is configured to generate a test pattern (correction pattern) for detection at the time of optical writing position correction, which is indicated by a portion surrounded by an alternate long and short dash line. A pattern generation unit 32 and a correction pattern storage unit 33 are included.

  The optical writing control unit 409 is connected to a variation factor detecting unit 500. The variation factor detection unit 500 includes a temperature / humidity sensor 501, a print page count unit 416, an operation unit 405, a cover detection unit 502, an image unit replacement detection sensor 503, an endless rotating unit replacement detection sensor 504, and the like. The variation factor detecting means 500 is scattered throughout the image forming apparatus, and is a generic name for these sensors.

  The optical writing control unit 409 according to the present embodiment includes information processing mechanisms such as the CPU 110, the RAM 111, the ROM 112, and the HDD 114 described with reference to FIG. 1. The optical writing control unit 409 as illustrated in FIG. Similar to the control unit 401 of the forming apparatus 1, a control program stored in the ROM 112 or the HDD 114 is loaded into the RAM 111 and operates according to the control of the CPU 110.

  The correction execution determination unit 31 receives the detection result of the variation factor detection unit 500 that can detect a change in the state of the image forming apparatus 100 in which the optical writing control unit 409 is mounted. Whether or not correction execution is necessary is determined according to the detection result.

  As the variation factor detection unit 500, the temperature and humidity sensor 501 and the temperature and / or humidity inside or outside the image forming apparatus 100 are detected. The print page count unit 416 is provided in the print job management unit 406 shown in FIG. 3 and counts the cumulative number of print pages.

  Further, although there is no specific detection means as the variation factor detection means 500, when the main power supply of the image forming apparatus 100 is turned on, the correction execution determination unit 31 detects that by starting to supply power. To do.

  In addition, the operation unit 405 that also functions as the variation factor detection unit 500 detects that the user is instructed to switch the power mode (power ON / OFF, energy saving mode, standby mode, drive mode) as a change in the device state. To do.

  The correction execution determination unit 31 includes (A) a change in temperature and humidity, (B) that the cumulative number of printed pages has reached a predetermined number, (C) the main power supply ON, and (D) the power supply mode. When switching, it is determined that “the change in the apparatus state is a change in which the positions of the photosensitive member (photosensitive drum) 9 and the exposure unit (solid scanning head) 11 do not change”.

  Further, as the variation factor detection unit 500, a cover detection unit 502 detects opening and closing of a cover provided in the housing of the image forming apparatus 100. The image unit replacement detection sensor 503 detects that an image unit (image forming unit 6), that is, a unit including the photoconductor 9 has been replaced. The endless rotating body replacement detection sensor 504 detects that the intermediate transfer belt 19 or the conveyance belt 5 has been replaced.

  The correction execution determination unit 31 determines that the variation factors of the apparatus are (E) cover opening / closing, (F) replacement of the image unit, and (G) replacement of the endless rotating body. 9 and the position of the exposure means 11 are both changed. Note that “the change in the apparatus state is a change in which the positions of the photoconductor 9 and the exposure unit 11 both fluctuate” includes a case in which there is a possibility of fluctuation in addition to the actual fluctuation.

  The correction pattern storage unit (correction pattern storage unit) 33 uses a correction pattern (test pattern, correction) including a first correction pattern group composed of horizontal lines and a second correction pattern group composed of diagonal lines used for correction. Pixel information) is stored.

  The correction pattern generation unit (correction pattern generation unit) 32 generates a correction pattern using both the first correction pattern group and the second correction pattern group according to the result of the variation factor detection unit 50. The correction pattern is generated by selecting the case where the correction pattern is generated using only the first correction pattern group. Details of the correction pattern will be described later with reference to FIGS.

  Specifically, when the correction execution determination unit 31 determines that “the change in the apparatus state is a change in which the positions of the photoconductor 9 and the exposure unit 11 both fluctuate”, the correction pattern generation unit 32 determines the first correction pattern. A correction pattern is generated using both the group and the second correction pattern group.

  On the other hand, when the correction execution determination unit 31 determines that “the change in the apparatus state is a change in which the positions of the photoconductor 9 and the exposure unit 11 do not change”, the correction pattern generation unit 32 determines the first correction pattern group. A correction pattern is generated using only

  The light emission control unit 34 is a light source control unit that controls the LED A 11 based on image information input from the print request receiving unit 404 or the reading unit 408 via the control unit 401. That is, the light emission control unit 34 also functions as a pixel information acquisition unit. The light emission controller 34 realizes optical writing on the photosensitive drum 9 by causing the LEDA 11 to emit light at a predetermined line cycle.

  The line cycle in which the light emission control unit 34 controls the light emission of the LEDA 11 is determined by the output resolution of the image forming apparatus 1. However, as described above, the light emission control is performed when scaling is performed in the sub-scanning direction in accordance with the ratio with the paper conveyance speed. The unit 34 performs scaling in the sub-scanning direction by adjusting the line period.

  The light emission control unit 34 is input from the correction pattern generation unit 32 as described above in the drawing parameter correction process in addition to driving and controlling the LEDA 11 based on the drawing information input from the control unit 401. The LEDA 11 is driven and controlled also when a correction pattern (correction pattern) is drawn.

  As described in FIGS. 1 and 2, a plurality of LEDA 11 are provided corresponding to each color. Therefore, as shown in FIG. 5, a plurality of light emission control units 34 are also provided so as to correspond to the plurality of LEDs A11.

  The correction value generated as a result of the positional deviation correction process in the drawing parameter correction process is stored as a positional deviation correction value in the correction value storage unit 39 shown in FIG. The light emission control unit 34 corrects the timing for driving the LEDA 11 based on the positional deviation correction value stored in the correction value storage unit 39.

  Specifically, the drive timing of the LEDA 11 is corrected by the light emission control unit 34 by delaying the timing for driving the LEDA 11 to emit light on the basis of the drawing information input from the control unit 401, that is, by shifting the line. Realized.

  On the other hand, since the drawing information is sequentially input from the control unit 401 according to a predetermined cycle, the input drawing information is held and read in order to shift the line and delay the light emission timing. It is necessary to delay the timing.

  Therefore, the light emission control unit 34 is connected to the line memory 410 as a storage medium for holding drawing information input for each main scanning line, and stores the drawing information input from the control unit 401 in the line memory 410. Hold by letting.

  In the misregistration correction process, the count unit 35 starts counting at the same time as the light emission control unit 34 controls the LEDA 11 to start exposure of the photoconductor 9BK. The count unit 35 acquires a detection signal that is output when the sensor control unit 37 detects a positional deviation correction pattern based on the output signals of the pattern detection sensors 17 and 18. Further, the count unit 35 inputs the count value at the timing when the detection signal is acquired to the correction value calculation unit 36. That is, the count unit 35 functions as a detection timing acquisition unit that acquires pattern detection timing.

  The sensor control unit 37 is a control unit that controls the pattern detection sensors 17 and 18, and as described above, based on the output signals of the pattern detection sensors 17 and 18, a misregistration correction pattern formed on the transport belt 5. However, it is determined that the positions of the pattern detection sensors 17 and 18 have been reached, and a detection signal is output. That is, the sensor control unit 37 functions as a detection signal acquisition unit that acquires pattern detection signals from the pattern detection sensors 17 and 18.

  In addition, the sensor control unit 37 acquires the signal strength of the output signals of the pattern detection sensors 17 and 19 and inputs the signal strength to the correction value calculation unit 36 when performing density correction using the density correction pattern. Further, the sensor control unit 37 adjusts the detection timing of the density correction pattern in accordance with the detection result of the positional deviation correction pattern.

  The correction value calculation unit 36 is based on the count value acquired from the count unit 35 and the signal intensity of the detection result of the density correction pattern acquired from the sensor control unit 37. The correction value is calculated based on the reference value for density correction. The correction value calculation unit 36 functions as a reference value acquisition unit and a correction value calculation unit. The reference value storage unit 38 stores a reference value for use in such calculation.

  A configuration of the solid-state scanning head (LEDA) 11 controlled by the optical writing control unit 401 as described above will be described.

<Configuration of exposure means>
6A and 6B show the configuration of the solid-state scanning head 11 (exposure means), where FIG. 6A shows writing by LD (Laser Diode), and FIG. 6B shows the optical path of writing by LED (Light Emitting Diode). It is.

<LD writing>
As shown in FIG. 9A, in the LD optical device 70, a light beam emitted from a laser light source such as a semiconductor laser is deflected by a polygon mirror 71 and is incident on an fθ lens 72. After passing through the fθ lens 72, the light beam is reflected and deflected by a plurality of reflecting mirrors 73, 74, 75, and irradiates the photosensitive member in an image form.

  Here, the polygon mirror 71, the fθ lens 72, and the reflection mirrors 73, 74, and 75 are surrounded by a sheet metal or a mold as the LSU unit 76, and the polygon motor serving as a heat source is also in the vicinity, so that it is easily affected by heat.

  For this reason, main scanning color misregistration is likely to occur due to lens rotation irregularities due to polygon motor rotation and thermal expansion, and the optical path length is long as shown by the arrow, and therefore even a slight color misregistration tends to amplify the misregistration.

<LED writing>
As shown in FIG. 6B, the solid-state scanning head 11 that is an LED optical device includes an LED substrate 61 and a lens array 64. In the LED substrate 61, a plurality of LED chips 62, which are LED light sources, are arranged to constitute an LED array 63 as a chip row, and the LED arrays 63, which are chip rows, are arranged in a staggered manner.

  In the lens array 64, a plurality of lenses are provided in close contact. Note that the arrangement of the chips and lenses is not limited to the shape shown in FIG. 6B, but may be other shapes.

  As shown in FIG. 6, there are misalignment when mounting the chip and misalignment when assembling the lens array. However, once corrected in a fixed state on the machine, there is no mirror, so the optical path will not move thereafter. The main scanning color misregistration hardly occurs.

  Compared to FIG. 6A, it is not necessary to enclose the LED substrate 61 and the lens array 64 as a unit, and since there is no heat source such as a polygon motor nearby, it is difficult to be affected by heat itself. Furthermore, there are chip position fluctuation and lens deformation due to thermal expansion, but the influence is small because the optical path length is short compared with LD.

  Therefore, in an image forming system in which LED writing is fixedly installed in a machine, main scanning color misregistration correction only needs to be performed when a unit such as a photoconductor or an intermediate transfer belt is replaced. Further, in an image forming system in which LED writing is retracted in conjunction with opening and closing of the cover, main scanning color misregistration correction may be executed even when the cover is opened and closed.

<Example of correction pattern>
FIG. 7 is a diagram for explaining a color misregistration detection pattern. Specifically, FIG. 7 shows an example of a color misregistration detection pattern row formed on an endless rotating body (the conveyance belt 5 or the intermediate transfer belt 19).

  As shown in FIG. 7, the color misregistration correction pattern (correction pattern image) is a total of four rows in which horizontal line patterns or diagonal line patterns composed of four colors Y, Bk, M, and C are arranged near each other. The horizontal line pattern 203 is formed as one set and the diagonal line pattern 204 is formed as one set (201). The oblique line pattern has an inclination angle of 45 ° in the belt conveyance direction (sub-scanning direction). The horizontal line pattern 203 is a first correction pattern group, and the oblique line pattern 204 is a second correction pattern group.

  As shown in FIG. 7, the color misregistration detection pattern row 210 is arranged in two rows along the sub-scanning direction according to the positions of the plurality of color misregistration detection pattern images 201, 201,. Configured. At this time, the color misregistration detection pattern images 201 are arranged along the sub-scanning direction (the rotation direction of the endless rotating body), for example, as a set of eight.

  The number of pattern sets and the pattern interval are set according to the size of the apparatus (machine size) and the like. It should be noted that the horizontal line pattern and the oblique line pattern may be arranged in other orders.

  When the endless rotating bodies (8, 19) on which the color misregistration detection pattern rows 210 are thus formed are conveyed in the sub-scanning direction, the pattern detection sensors 17, 19 are used to detect the color misregistration detection patterns. Move over 210.

  At this time, the correction pattern is detected by the sensor elements of the pattern detection sensors 17 and 18, and the color misregistration amount is calculated from the detection result to calculate the correction amount.

<Example of color misregistration detection pattern that is a variation factor affecting main scanning misalignment>
FIG. 8 is a diagram for explaining color misregistration detection in the main scanning direction and sub-scanning direction using a color misregistration detection pattern.
In order to calculate the color misregistration in the sub-scanning direction, the horizontal line pattern 203 is used, and the pattern intervals (y1, m1, c1) between the color K as the reference color and the other colors Y, M, and C are measured.

  Then, the color shift in the sub-scanning direction can be calculated by comparing the measurement result with the ideal distance of each color with respect to the reference color.

  On the other hand, when a main scanning color shift occurs in any of Y, Bk, M, and C, the detection position of the oblique line pattern changes, and the distance between the horizontal line and the oblique line pattern changes accordingly.

  In order to calculate the color shift in the main scanning direction, for each color, the distance (y2, k2, m2, c2) between each line of the horizontal line pattern 203 and each line of the oblique line pattern 204 is measured.

  Since each line of the oblique line pattern 204 has an angle of 45 ° with respect to the main scanning direction, the difference between the reference color (color K) and the other colors Y, M, and C in the measured interval is the color Y. , M, and C are the amount of color misregistration in the main scanning direction. For example, the color misregistration amount of the color Y in the main scanning direction is obtained by (k2-y2), the color misregistration amount of the color M in the main scanning direction is obtained by (k2-m2), and the color C main scanning direction. The color misregistration amount at is determined by (k2-c2).

  In this way, the color misregistration detection pattern image 201 including both the horizontal line pattern 203 and the oblique line pattern 204 can be used to obtain the color misregistration (registration misregistration) amounts in the sub-scanning direction and the main scanning direction.

  Such color misregistration amount detection processing can be executed using, for example, at least one color misregistration detection pattern image 201.

  However, by detecting the color misregistration amount for each color using the plurality of color misregistration detection pattern images 201, the color misregistration correction process can be performed with higher accuracy. For example, if the color misregistration amount calculated using a plurality of color misregistration detection pattern images 201 is subjected to statistical processing such as average value processing to calculate the color misregistration amount of each color, the detection accuracy is further improved. To do.

  In addition, the above-described color misregistration amount detection processing is performed using the sensors 17 and 18 having different positions in the main scanning direction, thereby detecting both components in the main scanning direction and the sub scanning direction for each misregistration amount. can do. For example, a skew component that is a deviation in the sub-scanning direction can be obtained by calculating a difference in the amount of color deviation in the sub-scanning direction detected by the sensor 17 and the sensor 18, respectively.

  In this manner, by combining and processing the detection results of the plurality of color misregistration detection pattern arrays 210 output from the sensors 17 and 18, (1) main scanning registration deviation, (2) sub-scanning registration deviation, and ( 3) Image forming conditions can be adjusted by correcting a plurality of items such as skew correction.

  Although not shown, a sensor is provided in the center and a pattern corresponding to the center is further formed to calculate the difference in deviation in the main scanning direction (belt width direction) and obtain the magnification error deviation. It is. When the magnification error deviation is corrected, the size of the image written on the photosensitive drum 9 may be adjusted by the light emission control unit 34 as writing means.

<Example of color misregistration detection pattern that is not a fluctuation factor affecting main scanning misalignment>
FIG. 9 is a diagram illustrating a horizontal line pattern specialized for color misregistration correction in the sub-scanning direction.

  At this time, only the sub-scanning resist misalignment is detected using the color misregistration detection pattern composed only of the horizontal line pattern 203 which is a horizontal line mark parallel to the main scanning direction shown in FIG.

  As described above, when there is no possibility that the variation factor may change the main scanning direction, only the pattern for correcting the sub-scanning direction may be formed to correct the color misregistration correction value. When a pattern is formed as shown in FIG. 6, it is not necessary to form a pattern for correcting the main scanning direction, so that toner can be saved and downtime can be shortened.

<Flow>
Next, a control flow at the start of the correction process of the optical writing control unit 409 according to the present embodiment will be described with reference to FIG.

  FIG. 10 is a flowchart at the start of the color misregistration correction process according to the embodiment of the present invention.

  As described above, color misregistration is necessary when the environment changes due to temperature, durability, or power control, and when the positions of the image carrier (photosensitive member 9) and the exposure unit 11 change or change. This is the case.

  Therefore, when the correction execution determination unit 31 of the optical writing control unit 409 detects that a variation factor has occurred, the flow of FIG. 10 is started.

  In step S1, the correction execution determination unit 31 determines whether or not the execution timing condition is satisfied.

  The execution timing condition indicates, for example, the timing at which a printing break is reached when a variation factor occurs during printing. Alternatively, when the image unit or the intermediate transfer belt is replaced, the timing when the cover of the housing is closed after the replacement. In addition, when the power is turned on or restored, it indicates the timing when the main board is started.

  In step S2, color misregistration correction is initially set. Specifically, the correction execution determination unit 31 instructs the control unit 401 to perform initial setting, and the control unit 401 causes the image forming process unit to execute initial setting.

  In order to perform color misregistration correction, a latent image (electrostatic latent image) and a toner image are created by the exposure unit and the image unit 6 by an image forming operation as in printing, and a conveyance path (conveyance path) It is necessary to transfer to the endless rotating body (5, 19). Therefore, when starting the color misregistration correction process other than during printing, the image forming unit 6 is started up by the initial setting in S2. Specifically, in the image forming unit, rotation driving of the photosensitive member 9, a stirring operation and a toner replenishing operation of the developer in the developing device 12, and a rotation operation of the developing roller are started, and the LED light source (LED array 63) of the exposure unit 11 is started. Is ready for irradiation.

  In S3, the correction execution determination unit 31 determines a color misregistration correction mode.

  Specifically, the correction execution determination unit 31 refers to, for example, Table 1 to determine whether or not the variation factor detected during the START is a variation factor that affects the main scanning deviation.

表１に示すように、ユーザー・サービスマンが行う動作のうち、カバー開閉と、画像ユニットの交換、着脱動作では、像担持体と露光手段の位置が共に変動する可能性が高い。

As shown in Table 1, among the operations performed by the user / serviceman, the positions of the image carrier and the exposure means are likely to fluctuate both when the cover is opened / closed and when the image unit is replaced / removed.

  The image unit attaching / detaching operation refers to, for example, an operation of temporarily removing the image unit in order to clear a paper jam in the housing. Replacement means replacing each unit with a new one.

  Therefore, in these cases, the process proceeds to step S4 as “it is a fluctuation factor affecting the main scanning deviation”.

  In step S4, the correction execution determination unit 31 instructs the correction pattern generation unit 32 to create both the horizontal line pattern and the diagonal line pattern shown in FIG. The correction pattern generation unit 32 reads out and creates both the horizontal line pattern and the diagonal line pattern from the correction pattern storage unit 33 and sends correction pattern data to the light emission control unit 34.

  On the other hand, in Table 1, the change in the durability state of the working member is the change in the surrounding environment during the printing operation, the change in the in-machine condition, the change in durability, the change in the power supply mode is the change in the image carrier and the exposure means. The position is likely to change together.

  Therefore, in these cases, it is determined that “it is not a fluctuation factor affecting the main scanning deviation” (No in S3), and the process proceeds to step S5.

  In step S5, the correction execution determination unit 31 instructs the correction pattern generation unit 32 to create only the correction pattern of only the horizontal line pattern shown in FIG. The correction pattern creation unit selects and reads only the horizontal line pattern from the correction pattern storage unit 33 and creates it, and sends the correction pattern data to the light emission control unit 34.

  In step S 6, the color detection sensor 17, 18 detects the color at a timing that matches the type (mode) of the correction pattern acquired by the light emission control unit 34, and the sensor control unit 37 can appropriately detect the color. Set the detection of deviation correction.

  As described above, since the color misregistration correction mode is selected according to the variation factor, when the variation factor affects the main scanning color misregistration, the normal color misregistration correction using the horizontal line / diagonal line pattern is executed, while the variation factor is determined. If the main scanning color shift is not affected, horizontal line color shift correction using only the horizontal line is executed.

  For this reason, the diagonal line for main scanning correction is omitted according to the cause of the color misregistration correction, and only the horizontal line is used. Correction-related downtime can be reduced.

<Comparative example>
FIG. 11 is an explanatory diagram of the color misregistration correction execution determination of the comparative example. As shown in FIG. 11, in the flow of the comparative example, there is no case classification according to the variation factor, and as shown in Table 2, the horizontal line / diagonal line pattern is obtained with all color misregistration corrections regardless of the variation factor. The normal color misregistration correction used is executed.

したがって、検出の際に、斜線パターンが増えると、図８に示すように、斜線パターンは横線パターンより、搬送路上の距離が長く、さらに全体のパターンの搬送路上の長さも増えるため、色ずれ補正起因のダウンタイムが長く発生してしまった。

Therefore, when the number of hatched patterns increases at the time of detection, as shown in FIG. 8, the hatched pattern has a longer distance on the transport path than the horizontal line pattern, and the length of the entire pattern on the transport path also increases. The resulting downtime has occurred for a long time.

  On the other hand, in the present invention, as shown in FIGS. 5 and 11, the diagonal lines for main scanning correction are omitted according to the cause of color misregistration correction, and only horizontal lines are used. Therefore, it is possible to reduce the downtime caused by the color misregistration correction, particularly during the printing operation, while maintaining the image quality regardless of the color misregistration correction system.

  As mentioned above, although this invention has been demonstrated based on each embodiment, this invention is not limited to the requirements shown in the said embodiment. With respect to these points, the gist of the present invention can be changed without departing from the scope of the present invention, and can be appropriately determined according to the application form.

5 Conveyor belt (endless rotating body, unit including endless rotating body)
6 Image forming unit (unit including photoconductor, image unit)
9 Photosensitive drum (photosensitive member)
11 Solid scanning head (LEDA, exposure means)
17, 18 Pattern detection sensor (correction pattern detection means)
19 Intermediate transfer belt (endless rotating body, unit including endless rotating body)
31 Correction execution determination unit 32 Correction pattern generation unit 34 Light emission control unit 61 LED substrate 62 LED chip 63 LED array (LED light source)
100, 100A Image forming apparatus 201 Color misregistration detection pattern image (correction pattern)
203 Horizontal line pattern (first correction pattern group)
204 Diagonal line pattern (second correction pattern group)
409 Optical writing control unit (optical writing control device)
500 Fluctuation factor detection means P Paper (recording medium)

Japanese Patent No. 6036059

Claims (12)

An optical writing control device that controls an exposure unit including an LED light source that exposes a rotatable photosensitive member to write an electrostatic latent image,
A light emission control unit that controls light emission of the LED light source based on information of pixels or correction patterns constituting an image to be imaged and output;
A correction pattern generation unit capable of generating a first correction pattern group consisting of horizontal lines and a second correction pattern group consisting of diagonal lines as the correction patterns, and sending the correction patterns to the light emission control unit;
The correction pattern image by the correction pattern detection means for detecting the correction pattern image on the endless rotating body on which the correction pattern image developed by developing the electrostatic latent image of the correction pattern formed on the photosensitive member is transferred and conveyed. A correction value calculation unit that calculates a correction value for correcting the writing position on the photoconductor by the LED light source controlled by the light emission control unit, based on the detection result of
Correction execution for determining whether or not correction execution using the correction pattern is necessary by inputting a detection result of a variation factor detecting means capable of detecting a change when a change occurs in the state of the apparatus on which the optical writing control apparatus is mounted. A determination unit, and
The correction pattern generation unit generates the correction pattern using both the first correction pattern group and the second correction pattern group according to the result of the variation factor detection unit; and An optical writing control device capable of selecting a case where the correction pattern is generated using only a correction pattern group. The optical writing control device according to claim 1;
A plurality of photoreceptors;
An exposure unit that includes a plurality of LED arrays in which a plurality of the LED light sources are arranged, and that writes the electrostatic latent image on each of the photoreceptors by emitting light from the plurality of LED light sources of each LED array;
An endless rotating body to which a correction pattern image obtained by developing an electrostatic latent image of a correction pattern formed on the photosensitive member is transferred and conveyed;
Correction pattern detection means for detecting the correction pattern image in the endless rotating body;
An image forming apparatus comprising: a variation factor detecting unit configured to detect a change in the state of the apparatus when a change occurs in the apparatus state of the image forming apparatus. When the correction execution determination unit determines that the change in the apparatus state detected by the variation factor detection unit is a change in which neither the position of the photoconductor nor the exposure unit varies.
The image forming apparatus according to claim 2, wherein the correction execution determination unit causes the correction pattern generation unit to generate the correction pattern using only the first correction pattern group. When the change in the device state detected by the variation factor detection means is a change in ambient temperature and humidity,
The image forming apparatus according to claim 3, wherein the correction execution determination unit causes the correction pattern generation unit to generate the correction pattern using only the first correction pattern group. When the change in the apparatus state detected by the variation factor detection means is that the cumulative number of printed pages has reached a predetermined number,
The image forming apparatus according to claim 3, wherein the correction execution determination unit causes the correction pattern generation unit to generate the correction pattern using only the first correction pattern group. When the correction execution determination unit determines that the change in the apparatus state is that the main power source of the image forming apparatus is turned on or the power mode of the image forming apparatus is changed,
The image forming apparatus according to claim 3, wherein the correction execution determination unit causes the correction pattern generation unit to generate the correction pattern using only the first correction pattern group. When the correction execution determination unit determines that the change in the state of the apparatus detected by the change factor detection unit is a change in which the positions of the photoconductor and the exposure unit both change,
The correction execution determination unit causes the correction pattern generation unit to generate the correction pattern using both the first correction pattern group and the second correction pattern group. Image forming apparatus. When the change in the apparatus state detected by the variation factor detection means is detection of opening / closing of a cover provided in a housing of the image forming apparatus,
The correction execution determination unit causes the correction pattern generation unit to generate the correction pattern using both the first correction pattern group and the second correction pattern group. Image forming apparatus. When the change in the apparatus state detected by the variation factor detection means is replacement of a unit including the photoconductor,
The correction execution determination unit causes the correction pattern generation unit to generate the correction pattern using both the first correction pattern group and the second correction pattern group. Image forming apparatus. When the change in the apparatus state detected by the variation factor detection means is replacement of a unit including the endless rotating body,
The correction execution determination unit causes the correction pattern generation unit to generate the correction pattern using both the first correction pattern group and the second correction pattern group. Image forming apparatus. 11. The intermediate transfer belt according to claim 2, wherein the endless rotator is an intermediate transfer belt on which images of respective colors formed on each of the plurality of photoconductors are transferred in a superimposed manner. The image forming apparatus according to one item. 11. The endless rotating body is a conveyance belt that conveys the recording medium in order to directly transfer an image of each color from the plurality of photosensitive members to the recording medium. The image forming apparatus described in 1.

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