JP2017211467A - Image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in which it is difficult to correctly perform color shift correction in a case where a heavy structure like a scanner is provided as a movable type even if a printer includes a color shift correction function since the weight to a printer unit being a support as a structure changes following the opening/closing state of the scanner and the structural distortion of a printer unit housing changes in an image formation apparatus having the heavy structure like the scanner as the movable type.SOLUTION: An image formation apparatus includes: an image recording unit 10 which detects a color shift amount between images in plural colors and performs color shift correction printing for correcting the color shift between the images in the plural colors on the basis of the color shift amount; an image reading unit 60 which is held in a freely rotatable manner with respect to the image recording unit 10; and an opening/closing sensor 19 which detects the opening/closing state of the image reading unit 60. The image recording unit 10 detects the color shift amount between the images in the plural colors at the state where the image reading unit 60 is closed and executes the color shift correction printing on the basis of the color shift amount.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus such as an electrophotographic printer, a copying machine, and a FAX, and more particularly to an image forming apparatus having a color misregistration correction function during printing.

  Conventionally, prior to a printing operation, a color misalignment correction operation is performed to improve positional accuracy, and various corrections are made to the detected misregistration amount to adjust the printing position (for example, for example, Patent Document 1).

  On the other hand, with the increasing functionality of image forming apparatuses, optional devices such as scanners are combined with printer apparatuses. This optional device is mounted integrally with the printer device, and is often mounted on the upper portion of the printer device for ease of user access and downsizing of the printer device. In particular, scanners are often positioned above the printer output unit to set the original, and there is a need to reduce the height of the device and reduce the size, as well as ease of access for the user to take out printing paper. In order to satisfy both, the scanner unit is mounted in a movable manner, and the scanner unit is flipped up to ensure accessibility to the discharge unit.

Japanese Unexamined Patent Publication No. 2001-134041 (5th page, FIG. 4)

  However, in an image forming apparatus that includes a movable structure such as the above-described scanner in a movable manner, the load applied to the printer unit that serves as a structure changes as the scanner is opened and closed, and the structure of the printer unit casing is changed. Distortion changes, and furthermore, it is difficult to prevent misalignment between each recording head and the image drum unit due to processing accuracy of unit parts constituting the device and mounting accuracy of the recording head to the device. The printing position on the recording medium was not constant.

  For this reason, even in a printing apparatus having a color misregistration correction function, when a heavy structure such as a scanner is provided in a movable manner, it is difficult to accurately perform color misregistration correction.

The present invention detects an amount of color misregistration between a plurality of color images, and performs color misregistration correction printing for correcting a color misregistration between the plurality of color images based on the amount of color misregistration, and the image recording In an image recording apparatus having a first posture with respect to a portion, a movable portion capable of taking a second posture other than the first posture, and a posture detecting portion for detecting the posture of the movable portion.
The image recording unit
A first color misregistration amount between the images of the plurality of colors when the movable portion is in the first posture is detected, and the color misregistration correction printing is performed based on the first color misregistration amount. And

  According to the present invention, it is possible to detect a color misregistration amount adapted to the posture of the movable part, and it is possible to perform optimum color misregistration correction printing.

1 is a main part configuration diagram showing a main part configuration of an image forming apparatus according to a first embodiment of the present invention; FIG. 2 is a schematic configuration diagram schematically showing an image forming unit for black (K) together with a transfer belt, a corresponding transfer roller, and a corresponding exposure head. FIG. 3 is an external perspective view illustrating a state in which the image reading unit is rotated to an open position with respect to the image recording unit and opened. FIG. 3 is an external perspective view illustrating a state in which the image reading unit is rotated to a closed position with respect to the image recording unit and closed. 2 is a block diagram illustrating a circuit configuration of a control system in an image recording unit of the image forming apparatus. FIG. FIG. 4 is an enlarged view showing a detection pattern printed on a transfer belt by 3 blocks in order to detect a color misregistration amount in the main scanning direction. It is a figure which shows the whole structure of the pattern for a detection for detecting the color shift amount in the main scanning direction. FIG. 4 is an enlarged view showing a detection pattern printed on a transfer belt by 3 blocks in order to detect a color misregistration amount in the sub-scanning direction. It is a figure which shows the whole structure of the pattern for a detection for detecting the color shift amount in a subscanning direction. It is a figure which shows another pattern for a detection which detects the color shift amount in a subscanning direction. 6 is a flowchart illustrating a process of color misregistration detection processing and color misregistration correction printing performed by the image forming apparatus according to the present exemplary embodiment.

Embodiment 1 FIG.
FIG. 1 is a main part configuration diagram showing a main part configuration of an image forming apparatus 1 according to the first embodiment of the present invention.

  As shown in FIG. 1, the image forming apparatus 1 includes an image recording unit 10 and an image reading unit 60 as a movable unit disposed above the image recording unit 10. The image reading unit 60 is described later. The image recording unit 10 is held openably and closably.

  The image recording unit 10 is configured as a color electrophotographic printer capable of printing four colors, for example, black (K), yellow (Y), magenta (M), and cyan (C), for forming a color image. As shown in the figure, a paper tray 11, an image forming unit 12, and a fixing device 13 are provided, and further, a paper feed roller 20 for conveying a recording paper 14 as a recording medium to each of these units, a pair of registration rollers 21, a pair of conveyance rollers 22 and 23, and a pair of discharge rollers 24.

  The paper tray 11 accommodates the recording paper 14 in a stacked state, and is detachably attached to the lower part in the image recording unit 10. The paper feed roller 20 takes out the recording paper 14 stored in the paper tray 11 one by one from the top and feeds it to the paper transport path. The registration roller pair 21 and the conveyance roller pair 22 correct the skew of the recording paper 14 and convey it to the image forming unit 12.

  The image forming unit 12 includes four image forming units 25, exposure heads 31 to 34, which are detachably disposed along the paper conveyance path, and toner images formed by the respective image forming units 25 as described later. 14 includes a transfer processing unit 41 that transfers the image by a Coulomb force.

  Four image forming units arranged in series in order from the upstream side of the sheet conveyance path, that is, an image forming unit 25K for black (K), an image forming unit 25Y for yellow (Y), and an image forming for magenta (M). The unit 25M and the image forming unit 25C for cyan (C) (which may be simply referred to as 25 when there is no particular distinction) all have the same configuration, and the color of the toner as the developer used, That is, only black (K), yellow (Y), magenta (M), and cyan (C) are different.

  The transfer processing unit 41 stretches the transfer belt 42 together with a transfer belt 42 that electrostatically attracts and conveys the recording paper 14, a drive roller 43 that is driven to rotate by a drive unit (not shown), and drives the transfer belt 42. The toner images formed on the surface of the photosensitive drum 101 are arranged so as to be in pressure contact with each other via the transfer belt 42 at positions facing the photosensitive drum 101 of the image forming units 25 and tension rollers 44a, 44b, 44c. And transfer rollers 35 to 38 to which a voltage is applied so as to be transferred onto the recording paper 14. The stacker 47 is formed on the upper side of the cover 46, and is stacked with the recording sheets 14 printed by the image recording unit 10 and discharged by the discharge roller pair 24.

  Here, the configuration of the image forming unit 25K including black (K) toner will be described. The image forming unit 25Y including yellow (Y) toner, the image forming unit 25M including magenta (M) toner, and the image forming unit 25C including cyan (C) toner differ only in toner color. Since the configuration is the same as that of the image forming unit 25K including black (K) toner, description thereof will be omitted.

  FIG. 2 is a schematic configuration diagram schematically showing a black (K) image forming unit 25 </ b> K together with the transfer belt 42, the corresponding transfer roller 35, and the corresponding exposure head 31.

  As shown in the figure, in the image forming unit 25K, a photosensitive drum 101 is rotatably arranged in the direction of the arrow, and around the photosensitive drum 101, the photosensitive drum 101 is sequentially arranged from the upstream side in the rotation direction. A charging roller 102 that contacts the surface of the substrate with a certain pressure to supply and charge the surface of the photosensitive drum 101; and an exposure head 31 that irradiates (exposes) light onto the surface of the charged photosensitive drum 101 to form an electrostatic latent image. Is disposed.

  Further, a developing unit 109 that generates a toner image by developing the electrostatic latent image by attaching toner 108 of a predetermined color (here, black) to the surface of the photosensitive drum 101 on which the electrostatic latent image is formed, and a photosensitive member A cleaning blade 104 is provided for removing residual toner remaining when the toner image on the drum 101 is transferred to the recording paper 14. For this reason, the cleaning blade 104 is formed of an elastic body, and the edge portion thereof is disposed so as to contact the surface of the photosensitive drum 101 with a constant pressure.

  The developing unit 109 stores and supplies toner 108 (here, black) and supplies the toner cartridge 105, the developing roller 103, the supply roller 106 that supplies the toner 108 supplied from the toner cartridge 105 to the developing roller 103, and the developing roller 103. A developing blade 107 for thinning the toner 108 is formed, and the electrostatic latent image formed on the surface of the photosensitive drum 101 is visualized, that is, developed by the thinned toner 108. The image forming unit 25K is configured to detachably dispose the toner cartridge 105 above the supply roller 106.

  The developing roller 103 and the supply roller 106 are arranged in parallel with each other so as to contact with each other at a constant pressure, and rotate in the direction of the arrow (same direction) shown in the figure. Further, as shown in the figure, the developing blade 107 and the developing roller 103 are arranged in parallel to each other such that, for example, a bent portion of the developing blade 107 contacts the peripheral surface of the developing roller 103 with a constant pressure.

  As shown in FIG. 1, transfer rollers 35 to 38 transfer the recording paper 14 by electrostatically absorbing and conveying the recording paper 14 at positions facing the respective photosensitive drums 101 of the five image forming units 25 described above. It is arrange | positioned in the state press-contacted via. These transfer rollers 35 to 38 respectively transfer the toner images on the corresponding photosensitive drums 101 to the recording paper 14. At the time of this transfer, the surface potentials of the photosensitive drums 101 and the respective photosensitive drums 101 are transferred. A voltage for applying a predetermined potential difference to the surface potential of the correspondingly arranged transfer rollers 35 to 38 is applied.

  The fixing device 13 includes a heating roller 13a and a pressure roller 13b inside, and fixes the toner image transferred onto the recording paper 14 by applying pressure and heating. In addition, the transfer process and the fixing process are executed by rotationally driving the transfer rollers 35 to 38 and the rollers of the fixing device 13 through a motor (not shown) in the main body of the image recording unit 10 and several gears of different systems. .

  Four paper sensors 15 to 18 arranged along the transport path detect the recording paper 14 being transported, and transmit a detection information signal to a printer control unit 153 (FIG. 5) described later based on the paper detection. To do.

  The image reading unit 60 is a unit that reads a document to obtain image information, and includes an operation panel 61 that is a user interface, such as a scanner unit and a FAX housed in the apparatus main body 62, and an image reading (not shown) that controls these. Consists of a control unit.

  3 and 4 are external perspective views of the image forming apparatus 1. FIG. 3 shows a state in which the image reading unit 60 is rotated to the open position with respect to the image recording unit 10, and FIG. In the figure, the image reading unit 60 is rotated to the closed position with respect to the image recording unit 10 and closed.

  The image reading unit 60 is arranged by the image recording unit 10 around a rotation shaft (not shown) disposed in the image recording unit 10 in the vicinity of the discharge roller pair 24 shown in FIG. It is held rotatably.

  The image forming apparatus 1 reads an original in the image reading unit 60 or prints in the image recording unit 10, but at least when reading an original in the image reading unit 60, as shown in FIG. The image reading unit 60 is executed with the image recording unit 10 closed. On the other hand, for example, when the printed recording paper 14 collected in the stacker 47 (FIG. 1) is taken out, the image reading unit 60 is opened with respect to the image recording unit 10 as shown in FIG. Thus, the printed recording paper 14 on the stacker 47 can be easily taken out.

  An open / close sensor 19 serving as a posture detecting unit disposed in the vicinity of the rotation axis of the image reading unit 60 monitors the opening / closing of the image reading unit 60, and the image reading unit 60 is in the open position shown in FIG. 4 transmits the opening / closing information that can determine whether or not it is in the closed position shown in FIG.

  FIG. 5 is a block diagram illustrating a circuit configuration of a control system in the image recording unit 10 of the image forming apparatus 1.

  In the figure, the host interface unit 150 transmits / receives data to / from a command / image processing unit 151, and the command / image processing unit 151 outputs image data to the exposure head interface unit 152. The exposure head interface unit 152 controls head drive pulses and the like by the printer control unit 153, and causes the exposure heads 31, 32, 33, and 34 for each color to emit light.

  The printer control unit 153 includes a microprocessor, a ROM, a RAM, an input / output port, a timer, and the like, and sends a voltage setting signal to the charging bias generation unit 161, the development bias generation unit 162, and the transfer bias generation unit 163. The charging bias generator 161 individually applies a charging bias voltage to the charging roller 102 (FIG. 1) of each image forming unit 25 for black (K), yellow (Y), magenta (M), and cyan (C). The developing bias generator 162 includes the developing roller 103 (FIG. 1), the supply roller 106, and the developing blade of each image forming unit 25 for black (K), yellow (Y), magenta (M), and cyan (C). A bias voltage is individually applied to 107 (FIG. 1).

  The transfer bias generation unit 163 is a transfer for each color, which is arranged to face the photosensitive drum 101 of each image forming unit 25 for black (K), yellow (Y), magenta (M), and cyan (C). A bias voltage is individually applied to the rollers 35, 36, 37, and 38.

  The printer control unit 153 includes a paper feed motor 154 that drives the paper feed roller 20, a registration motor 155 that drives the registration roller pair 21, a drive roller 43, a conveyance roller pair 22, 23, and a belt motor 156 that drives the discharge roller pair 24. , Four drum motors (K, Y) for individually driving the respective rotary members such as the fixing device motor 157 for driving the rollers 13a and 13b of the fixing device 13 and the photosensitive drum 101 of the image forming unit 25. , M, C) 158 is driven at a predetermined timing. The temperature of the fixing device heater 159 provided in the heating roller 13a of the fixing device 13 is controlled by the printer control unit 153 according to the detection value of the thermistor 165 that detects the temperature of the heating roller 13a.

  The reflection intensity detection mechanism 45 transmits reflection intensity detection information for executing color misregistration correction processing by the printer control unit 153 to the printer control unit 153, as will be described later.

  In the above configuration, the outline of the printing operation of the image forming apparatus will be described first.

  The image recording unit 10 inputs print data described in PDL (Page Description Language) or the like from an external device including the image reading unit 60 (FIG. 1) via the host interface unit 150 (FIG. 2). The input data is converted into bitmap data by the command / image processing unit 151 (FIG. 2). The image recording unit 10 starts the printing operation after setting the heating roller 13a of the fixing device 13 to a predetermined temperature by controlling the temperature of the fixing device heater 159 according to the detection value of the thermistor 165 (FIG. 2).

  The recording paper 14 set in the paper tray 11 is fed by the paper feed roller 20, and the recording paper 14 whose skew has been corrected by the registration roller pair 21 and the conveyance roller pair 22 is synchronized with an image forming operation described later. Then, it is conveyed onto the transfer belt 42. The four image forming units 25 form toner images on the internal photosensitive drum 101 by an electrophotographic process. At this time, each of the four photosensitive drums 101 is arranged correspondingly, and an electrostatic latent image is formed by the exposure heads 31 to 34 that are turned on according to the bitmap data, and developed by the corresponding developing roller 103. As a result, toner images of corresponding colors are formed.

  The toner images formed on the four photoconductive drums 101 are conveyed on the transfer belt 42 by the transfer bias voltages applied to the transfer rollers 35 to 38 disposed facing the photoconductive drums 101. The recording paper 14 is sequentially superimposed and transferred. After the four color toner images are transferred onto the recording paper 14, the recording paper 14 is further fixed by the fixing device 13, further conveyed, and discharged to the stacker 47.

  During the above-described printing operation, the printer control unit 153 shown in FIG. 5 sets a high-voltage output voltage according to a predetermined table value, and supplies a predetermined voltage to the charging bias generation unit 161, the development bias generation unit 162, and the transfer bias generation unit 163. Outputs a voltage setting signal. The charging bias generator 161 individually applies a bias voltage to the charging roller 102 (FIG. 2) of each image forming unit 25 based on the voltage setting signal, and the developing bias generator 162 based on the voltage setting signal. A bias voltage is individually applied to the developing roller 103, the supply roller 106, and the developing blade 107 (FIG. 2) of each image forming unit 25, and the transfer bias generating unit 163 generates each transfer roller 35 based on the voltage setting signal. Supply transfer bias voltage to .about.38.

  Here, an example of the printing position correction operation according to the color misregistration amount performed by the image recording unit 10 will be described.

  FIG. 6 is an enlarged view of the detection pattern printed on the transfer belt 42 by 3 blocks in order to detect the amount of color misregistration in the main scanning direction, and FIG. 7 shows the color in the main scanning direction. It is a figure which shows the whole structure of the pattern for a detection for detecting deviation | shift amount.

  Here, FIG. 6A shows a black pattern, and FIG. 6B shows a color (yellow (Y), magenta (M), or cyan (C) color) pattern. Has been. Here, the black and color patterns are shown as separate ones. Actually, however, first, a black pattern is printed on the transfer belt 42, and then yellow (Y), magenta (M), and cyan (C ) Is printed on top of it. 6 (a) and 6 (b), the transfer belt 42 runs in the right direction, and the fourth and subsequent blocks from the top are omitted.

  As shown in FIG. 6A, the black pattern to be printed first is obtained by drawing four striped patterns each having a width of 5 dots perpendicular to the main scanning direction at intervals of 5 dots. Four striped patterns are defined as one block, and nine blocks of striped patterns are linearly arranged in the belt running direction at regular intervals in the sub-scanning direction (see FIG. 7). Note that the four stripes of each block are all arranged at the same position in the main scanning direction.

  In the color pattern shown in FIG. 6B, the configuration of each block is the same as that of the black pattern, and the upper left position TL of the first block printed at the forefront is used as a reference. Thus, the print position in the sub-scanning direction is set so as to overlap the first block of the black pattern. On the other hand, the arrangement position of the leading block in the main scanning direction of the color pattern is set to a printing position shifted to the left by 4 dots to the left as compared with the black pattern. Then, in the second and subsequent blocks that are printed behind the first block in the sub-scanning direction, a printing position shifted to the right by one dot is set for each preceding block.

  As shown in FIG. 7, the black pattern previously printed on the transfer belt 42 is printed after the detection pattern composed of the black stripe pattern and the color pattern set in the above-described arrangement. As shown in FIGS. 7A and 7B, there are two types corresponding to the printing position shift in the main scanning direction of the color pattern with respect to the black pattern. The overlapping ratio of the detection patterns changes for each block. In addition, when the two types of detection patterns overlap in this way, the color toner and the underlying black toner are not fixed on the transfer belt 42, so that the color detection pattern is used. The covered black detection pattern is not seen through.

  In the case of FIG. 7A in which there is no print position shift in the main scanning direction, two types of detection patterns are completely overlapped in the fifth block counted from the front in the sub-scanning direction. FIG. 7B shows a case where the print position of the color detection pattern is shifted by 2 dots to the left in the main scanning direction with respect to black, and is the seventh position counted from the front in the sub-scanning direction. In this block, two types of detection patterns are completely overlapped. According to such a nine-block detection pattern, as the print position is shifted by one dot, the block number of the detection pattern that completely overlaps changes, so that there is a print position shift in the main scanning direction. If it is within 4 dots in the left-right direction, it can be detected.

  Next, a detection pattern used for correcting the printing position in the sub-scanning direction will be described.

  FIG. 8 is an enlarged view of the detection pattern printed on the transfer belt by 3 blocks in order to detect the color misregistration amount in the sub-scanning direction, and FIG. 9 is a color misregistration in the sub-scanning direction. It is a figure which shows the whole structure of the pattern for a detection for detecting quantity.

  Here, FIG. 8A shows a black pattern, and FIG. 8B shows a color (yellow (Y), magenta (M), or cyan (C) color) pattern. However, as in the case of color misregistration detection in the main scanning direction, these patterns are actually printed on the conveyance belt in a superimposed manner. As shown in FIG. 8A, the black pattern to be printed first is obtained by drawing four striped patterns each having a 5-dot width perpendicular to the sub-scanning direction at 5-dot intervals. Four striped patterns are arranged as one block, and nine blocks of striped patterns are linearly arranged in the belt running direction with a certain interval in the sub-scanning direction (see FIG. 9). Note that the four stripes of each block are all arranged at the same position in the main scanning direction.

  In the color pattern shown in FIG. 8B, the configuration of each block itself is the same as the arrangement of the black pattern, and in the main scanning direction, the left and right directions are the same in all the blocks. The print position is set so as to overlap the detection pattern. On the other hand, the arrangement position of the first block in the sub-scanning direction is set to a printing position shifted by 4 dots rearward in the sub-scanning direction compared to the black pattern.

  The color pattern of the second block is arranged at the printing position shifted by 3 dots backward in the sub-scanning direction compared to the black pattern. Similarly, in each block printed subsequent to the rear in the sub-scanning direction, the shift amount is decreased by one dot from the previous block, and in the last nine blocks, the shift amount is increased forward in the sub-scanning direction. They are arranged at printing positions shifted by 4 dots.

  When the black and color striped patterns arranged in this way are overlaid on the transfer belt 42 and printed, the color pattern with respect to the black pattern corresponds to the printing position shift in the sub-scanning direction as shown in FIG. As shown in a) and (b), the overlapping ratio of the two types of detection patterns changes for each block. In the case of FIG. 9A in which the printing position in the sub-scanning direction is not shifted, two types of detection patterns are completely overlapped in the fifth block counted from the front in the sub-scanning direction. FIG. 9B shows a case where the printing position of the color pattern is shifted backward by 2 dots in the sub-scanning direction with respect to black, and 2 in the seventh block counted from the front in the sub-scanning direction. There are overlapping types of detection patterns. According to such a 9-block detection pattern, as in the case of color misregistration detection in the main scanning direction, it is possible to detect printing position misregistration within a range of 4 dots in the sub scanning direction.

  In FIG. 9, in order to detect the color misregistration amount in the sub-scanning direction, the detection pattern in which one stripe is composed of four stripes has been described. However, even in the case of a detection pattern having only one stripe per block, it is possible to detect a printing position shift similarly. FIG. 10 is a diagram showing another detection pattern for detecting the color misregistration amount in the sub-scanning direction. In the case of a block composed of a single stripe, even if the length of the entire detection pattern is shortened, the same color misregistration can be detected, so that it is possible to reduce the time spent for color misregistration detection.

  Next, the printing position correction operation according to the color misregistration amount will be specifically described.

  First, a correction procedure for eliminating color misregistration in the main scanning direction of yellow (Y) with respect to black (K) will be described.

  First, only the transfer belt 42 is driven in a state in which paper feeding is stopped, and the black (K) image forming unit 25K and the transfer roller 35 form a detection pattern in the main scanning direction with black toner on the surface of the transfer belt 42. Print. Subsequently, a detection pattern in the main scanning direction using yellow toner is printed by the image forming unit 25Y and the transfer roller 36 for yellow (Y) so as to overlap with the black detection pattern.

  As a result, a detection pattern as shown in FIG. 7 is printed on the transfer belt 42 and sequentially sent before the reflection intensity detection mechanism 45 (FIG. 1). The reflection intensity detection mechanism 45 outputs an optical signal corresponding to the reflectance of each block to the printer control unit 153 as an electrical signal corresponding to the density level. The storage means (RAM) of the printer controller 153 stores the amount of yellow color misregistration with respect to black based on the block position where the highest output is detected.

Here,
The reflectance of the color toner> the reflectance of the transfer belt 42> the reflectance of the black (K) toner, and the output of the reflection intensity detection mechanism 45 is such that the color pattern completely overlaps the black (B) pattern. The black (B) pattern and the color pattern are shifted, and the output decreases as the black pattern is exposed.

  After the yellow color misregistration amount is measured, the detection pattern on the transfer belt 42 is scraped off to the waste toner tank 49 by the cleaning mechanism constituted by the tension roller 44a and the cleaning blade 48 shown in FIG.

  The procedure for storing the color misregistration in the main scanning direction of magenta (M) and cyan (C) with respect to black (K) is performed in the same manner as in the case of yellow (Y), and magenta (M) and cyan (C), respectively. Is stored. The print position shift in the main scanning direction is corrected as follows based on the color shift amount of each color detected in this way.

  The color misregistration in the main scanning direction can be corrected by changing the timing of sending image data with respect to the data transfer clock. That is, when the yellow (Y) toner printing position is shifted by one dot to the right in the main scanning direction with respect to the black (K) toner printing position, for example, the positional shift signal is sent from the printer control unit 153 to the exposure head interface. Notification to the unit 152. The exposure head interface unit 152 shifts the yellow (Y) image printing position by one dot to the left by advancing the output timing of the yellow (Y) image signal to the yellow (Y) image forming unit 25Y by one dot. Correction is performed.

  With respect to the print positions of other color images, the color misregistration can be eliminated if the same position correction is performed with reference to the print position by the exposure head 31 of the black (K) image forming unit 25K. In this way, by correcting the printing position in the main scanning direction for all color image data, printing without color misregistration in the main scanning direction becomes possible.

  Even in the printing position correction operation in the sub-scanning direction, the detection of the color misregistration amount for each of yellow (Y), magenta (M), and cyan (C) uses a detection pattern for detecting the color misregistration amount in the sub-scanning direction. Thus, the detection is performed in the same manner as the detection of the color misregistration amount in the main scanning direction. However, in the correction procedure for eliminating color misregistration in the sub-scanning direction, the yellow (Y) toner printing position is deviated by, for example, 3 dots rearward in the sub-scanning direction with respect to the black (K) toner printing position. In this case, the positional deviation signal is notified from the printer control unit 153 to the exposure head interface unit 152.

The exposure head interface unit 152 shifts the print position of the yellow (Y) image by 3 dots forward by changing the output of the image data in the command / image processing unit 151 to a forward value by 3 dots and outputting it. Correction is performed. Similarly, by correcting the print positions in the sub-scanning direction for all color image data, printing without color misregistration in the sub-scanning direction becomes possible.
Hereinafter, the operation of detecting the color misregistration amount of each color by the above-described method is referred to as color misregistration amount detection processing. Based on the detected color misregistration amount (correction value), the printing position and the print timing are corrected to eliminate the color misregistration. The printing process performed in this way may be referred to as color misregistration correction printing.

  Next, color misregistration detection processing and color misregistration correction printing performed by the image forming apparatus 1 according to the present embodiment will be described.

  Here, the printer control unit 153 includes a memory (RAM) that individually stores each color misregistration amount detected corresponding to each open state or closed state detected by the open / close sensor 19. According to the state, it is possible to select a color misregistration amount (correction value) to be used for color misregistration correction printing, and also hold information on whether or not the correction value needs to be updated with new and old information as correction values.

  This new / old information is set as “old” information when exchanging consumables, when a certain number of printing operations are completed, etc., and holds that the correction value needs to be updated by performing a new color misregistration detection process. Is for. On the other hand, if the new / old information is in a “new” state, a new color misregistration amount detection process is not performed.

  Hereinafter, the flowchart shown in FIG. 11 shows the process of color misregistration detection processing and color misregistration correction printing performed by the image forming apparatus 1 of the present embodiment. The operation of the image forming apparatus 1 of the embodiment will be further described.

  First, after the main power is turned on, the image forming apparatus 1 transmits a print operation instructed by the user to the image recording unit 10 as a print job, and receives the print job received by the host interface unit 150 from the printer control. Under the control of the unit 153, the command / image processing unit 151 and the exposure head interface unit 152 perform processing to prepare for starting the printing operation.

That is, when a print job is generated (step S100), the printer control unit 153 confirms the open / closed state of the image reading unit 60 (FIGS. 1, 3 and 4) based on information from the open / close sensor 19 (step 101). When the image reading unit 60 is in the closed position (step 101, Yes), the old and new state of the color misregistration amount (correction value) corresponding to the closed state of the image reading unit 60 is confirmed (step 102).
The new / old information here is recorded as “old” information when the consumables are replaced or when a certain number of printing operations are completed. This is done by setting and confirming a flag recorded as information.

  When the color misregistration amount (correction value) is “new” information (No in step S102), the image reading unit 60 based on this color misregistration amount (correction value) is used as a correction value that is not required to be updated. Color misregistration correction printing is executed (steps S103 and S118).

  On the other hand, when it is determined in step S102 that the color misregistration amount (correction value) is “old” information (step S102, Yes), the above described new color misregistration amount detection when the image reading unit 60 is in the closed state is performed. The process is started (step S104), and the color misregistration amount detection process is executed while monitoring that the image reading unit 60 is in the closed position (steps S105 and S106).

  If it is detected that the image reading unit 60 is in the open position during the color misregistration amount detection process (No in step S105), the process is interrupted and the process returns to step S101, and the image reading unit 60 is in the closed state. If the color misregistration amount detection process is completed as it is (Yes in step S106), the correction data to be stored is updated with the newly detected color misregistration amount (correction value), and the new and old information is changed to "new" information (step S107). ), Based on the updated color misregistration amount (correction value), the image reading unit 60 executes color misregistration correction printing in a closed state (step S118).

On the other hand, after the print job is generated (step S100) or during the color misregistration amount detection process in the closed state of the image reading unit 60, the image reading unit 60 is in the open position (No in step S105), and the image reading unit. If it is detected that 60 is in the open position (step 101, No), the old and new state of the color misregistration amount (correction value) corresponding to the open state of the image reading unit 60 is confirmed (step 112).
The new / old information here is recorded as “old” information when the consumables are replaced or when a certain number of printing operations are completed. This is done by setting and confirming a flag recorded as information.

  When the color misregistration amount (correction value) is “new” information (No in step S112), the image reading unit 60 based on this color misregistration amount (correction value) as an update-unnecessary correction value is in an open state. Color misregistration correction printing is executed (steps S113 and S118).

  On the other hand, when it is determined in step S112 that the color misregistration amount (correction value) is “old” information (step S112, Yes), the new color misregistration amount detection described above when the image reading unit 60 is in the open state. The process is started (step S114), and the color misregistration amount detection process is executed while monitoring that the image reading unit 60 is in the open position (steps S115 and S116).

  If it is detected that the image reading unit 60 is in the closed position during the color misregistration detection process (No in step S115), the process is interrupted and the process proceeds to step S102, and the image reading unit 60 is in the open state. If the color misregistration amount detection process is completed as it is (Yes in step S116), the correction data to be stored is updated with the newly detected color misregistration amount (correction value) so that the new and old information becomes the "new" information (step) S117) Based on the updated color misregistration amount (correction value), the image reading unit 60 executes color misregistration correction printing under the open state (step S118). When the process proceeds to step S102, the above-described series of processing is repeated when the image reading unit 60 is closed.

  As described above, according to the image forming apparatus 1 of the present embodiment, when a print job is generated and the image reading unit 60 is in a closed (open) state, stored correction data corresponding to the state is stored. When the correction data is determined to be “new”, the image reading unit 60 executes color misregistration correction printing under the closed (open) state based on the stored correction data. When the stored correction data is determined to be “old”, a color misregistration amount detection process is newly executed in a closed (open) situation, and the newly detected correction data is used as “new” information. In addition to updating the memory, color misregistration correction printing is performed under the closed (open) state of the image reading unit 60 based on the correction data of the “new” information.

  Further, when the open / close state of the image reading unit 60 changes during the color misregistration detection process, color misregistration correction printing is performed through the above-described process based on the changed state.

  In the present embodiment, when the open / close state of the image reading unit 60 changes during the color misregistration detection process, an example of executing color misregistration correction printing through the above process based on the state after the change is shown. However, if the open / close state of the image reading unit 60 changes during execution of color misregistration correction printing, the printing operation is already being performed, and thus the correction value may not be correctly reflected when the printing operation is completed. For example, the information may be displayed on the operation panel 61 and notified to the user.

  Further, in the present embodiment, an example of performing color misregistration amount detection processing in each state according to the open / closed state of the image reading unit 60, storing each correction value, and executing color misregistration correction printing according to each state. However, the present invention is not limited to this, and in order to simplify the configuration and the processing process, when the image reading unit 60 is in an open state, information for prompting the image reading unit 60 to close is displayed, for example, on the operation panel. The above-described series of color misregistration amount detection processing and color misregistration correction printing are executed only when the image reading unit 60 is in the closed state. You may comprise.

  Further, in consideration of simplification, when executing color misregistration correction printing in an open state, a predetermined color misregistration correction value (initial value or correction value in a closed state) is set without performing color misregistration amount detection processing. The present invention may be configured such that a printing operation is performed only by application and that an accurate color misregistration correction printing is not performed, for example, is displayed on the operation panel to notify the user. It can be taken.

  As described above, according to the image forming apparatus of the present embodiment, the color misregistration correction printing is performed in consideration of the distortion of the casing caused by the open / closed state of the image reading unit 60. Therefore, the color misregistration is always stably performed. It is possible to provide an image forming apparatus that is capable of printing a color image that is suppressed and has excellent print quality.

  In the present embodiment, the image forming apparatus including the image recording unit 10 and the image reading unit 60 rotatably held on the image recording unit 10 is described. However, the present invention describes the image recording unit 10 and the image recording unit. The present invention can also be applied to an apparatus that combines an accessory device, a cover, a paper feed unit, and the like with a behavior that causes distortion to ten cases.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus, 10 Image recording part, 11 Paper tray, 12 Image forming part, 13 Fixing device, 13a Heating roller, 13b Pressure roller, 14 Recording paper, 15 Paper sensor, 16 Paper sensor, 17 Paper sensor, 18 Paper Sensor, 19 Open / close sensor, 20 Paper feed roller, 21 Registration roller pair, 22 Transport roller pair, 23 Transport roller pair, 24 Discharge roller pair, 25 Image forming unit, 31 Exposure head, 32 Exposure head, 33 Exposure head, 34 Exposure Head, 35 Transfer roller, 36 Transfer roller, 37 Transfer roller, 38 Transfer roller, 41 Transfer processing section, 42 Transfer belt, 43 Drive roller, 44a Tension roller, 44b Tension roller, 44c Tension roller, 45 Reflection intensity detection mechanism, 46 Cover, 47 stacker 48 cleaning blade, 49 waste toner tank, 60 image reading unit, 61 operation panel, 62 apparatus main body, 101 photosensitive drum, 102 charging roller, 103 developing roller, 104 cleaning blade, 105 toner cartridge, 106 supply roller, 107 developing blade , 108 toner, 109 developing unit, 150 host interface unit, 151 command / image processing unit, 152 exposure head interface unit, 153 printer control unit, 154 paper feed motor, 155 registration motor, 156 belt motor, 157 fixing device motor, 158 Drum motor (K, Y, M, C), 159 Fixer heater, 161 Charging bias generator, 162 Development bias generator, 163 Transfer bias generator, 165 Thermistor

Claims (9)

An image recording unit that detects a color misregistration amount between a plurality of color images and performs color misregistration correction printing that corrects a color misregistration between the plurality of color images based on the color misregistration amount;
A movable part capable of taking a first posture with respect to the image recording unit and a second posture other than the first posture;
In an image recording apparatus having a posture detection unit that detects the posture of the movable unit,
The image recording unit
A first color misregistration amount between the images of the plurality of colors when the movable portion is in the first posture is detected, and the color misregistration correction printing is performed based on the first color misregistration amount. An image forming apparatus.   A second color misregistration amount between the images of the plurality of colors when the movable portion is in the second posture is detected, and the color misregistration correction printing is executed based on the second color misregistration amount. The image forming apparatus according to claim 1.   When the posture of the movable portion changes during detection of the first color shift amount or the second color shift amount, the color shift amount corresponding to the post-change posture is detected, and the detected color shift amount is detected. The image forming apparatus according to claim 2, wherein the color misregistration correction printing is executed based on the image forming apparatus.   The first color misregistration amount and the second color misregistration amount are stored in the storage unit as correction values accompanied by new and old information. When the old and new information is “new”, the first color misregistration amount and the second color misregistration amount are based on the already stored correction values. The color misregistration correction printing is executed, and when the old and new information is “old”, the color misregistration correction printing is executed based on the correction value which is newly detected and the old and new information is “new”. The image forming apparatus according to claim 2 or 3,   2. The user is informed that color misregistration correction printing has not been performed based on a correct correction value when the posture of the movable portion changes during execution of the color misregistration correction printing. 5. The image forming apparatus according to any one of 4 above.   The image forming apparatus according to claim 1, wherein when the movable portion is in the second posture, the user is notified to change to the first posture.   When the movable portion is in the second posture, the color misregistration correction printing is executed based on a predetermined color misregistration correction value, and the color misregistration correction printing is not performed based on a correct correction value. The image forming apparatus according to claim 1, wherein the image forming apparatus is notified.   The image forming apparatus according to claim 1, wherein the movable unit is an image reading unit that is rotatably held by the image recording unit. The first posture indicates a state in which the image reading unit is in a closed position that is a rotational position for closing the upper portion of the image recording unit, and the second posture is determined by the image reading unit. 9. The image forming apparatus according to claim 8, wherein the image forming apparatus is in an open position in which an upper portion of the section is opened.

Images