JP4862526B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that prints a registration mark.

  2. Description of the Related Art Conventionally, a color image forming apparatus using a transfer type electrophotographic system has tandem printing units of four colors of black (K), cyan (C), magenta (M), and yellow (Y) in the conveyance direction of recording paper. It is arranged. The four-color printing unit forms a latent image on the photosensitive drum based on the image data, develops the latent image with the color toner of the developing device, and then transfers the toner onto the recording paper conveyed at a constant speed. A color image is formed by superimposing and transferring and fixing the images. At this time, it is necessary to increase the accuracy of color matching by reducing the positional deviation of the toner image to be transferred.

Therefore, a printing apparatus is known in which a registration mark is transferred with each color toner onto a belt, the registration mark is detected by a sensor, the position of the registration mark is detected, and the positional deviation of the registration mark is detected (patent) Reference 1).
JP 11-157134 A

  However, in the technique described in Patent Document 1, when a toner image is directly transferred onto a recording sheet without using a belt, if the image density changing function of the image forming apparatus sets a low density, There is a problem that the density of the mark becomes low and the registration mark cannot be detected with high accuracy.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of securing a density necessary for accurately detecting a registration mark.

  In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention includes a print head including a plurality of light emitting elements arranged along the main scanning direction, and a first strobe signal for generating a registration mark recording. And a second signal generating unit for generating a strobe signal for image recording, and the first signal generating unit is connected to a plurality of light emitting elements for recording registration marks on at least one end side of the print head. And a signal circuit in which the second signal generator is connected to a light emitting element group composed of a plurality of light emitting elements for image recording.

  According to the image forming apparatus of the first aspect of the invention, the first signal generator generates a strobe signal for register mark recording and emits light comprising a plurality of light emitting elements for register mark recording on at least one end side of the print head. Output to the element group. On the other hand, the second signal generator generates a strobe signal for image recording and outputs it to a light emitting element group composed of a plurality of light emitting elements for image recording of the print head.

  Here, even if the density of the recorded image is set low and the strobe signal of the image recording light emitting element group is changed, the registration mark recording strobe signal generated by the first signal generator is not changed.

  In this way, a registration mark recording strobe signal is generated for the registration mark recording light emitting element group, and an image recording strobe signal is generated for the image recording light emitting element group. Even if the density of the image to be changed is changed, it is possible to ensure the density necessary for detecting the registration mark with high accuracy.

  According to a second aspect of the present invention, there is provided an image forming apparatus comprising: a print head including a plurality of light emitting elements arranged along a main scanning direction; and a plurality of signal generating units for generating a strobe signal. A signal circuit connected to each of a plurality of light emitting element groups composed of a plurality of light emitting elements for register mark recording and a plurality of light emitting element groups composed of a plurality of light emitting elements for image recording, and a width of a recording medium on which an image is formed Based on the information, a strobe signal for register mark recording is generated in the signal generating unit connected to at least one of the plurality of light emitting element groups for register mark recording, and the light emitting element group for image recording is included. The signal generation unit connected to another light emitting element group includes signal generation control means for generating a strobe signal for image recording.

  According to the image forming apparatus of the second invention, the signal generation control unit is connected to at least one of the plurality of light emitting element groups for recording the registration mark based on the width information of the recording medium on which the image is formed. A strobe signal for registration mark recording is generated in the signal generation unit, and the strobe signal for registration mark recording is output to the light emitting element group corresponding to the recording position of the registration mark corresponding to the width of the recording medium. On the other hand, the signal generation control unit generates a strobe signal for image recording in a signal generation unit connected to another light emitting element group including the light emitting element group for image recording, and generates an image corresponding to the width of the recording medium. A strobe signal for image recording is output to the light emitting element group corresponding to the recording position.

  Here, even if the density of the image to be recorded is set low and the strobe signal of the light emitting element group for image recording is changed, the strobe signal for registration mark recording is not changed.

  As described above, a registration mark recording strobe signal is generated for the registration mark recording light emitting element group corresponding to the width information of the recording medium, and the image recording light emitting element group is subjected to image recording. Since the strobe signal is generated, even if the density of the recorded image is changed, it is possible to ensure the density necessary for accurately detecting the registration mark.

  The image forming apparatus includes an image carrier on which an electrostatic latent image is formed on a surface by a print head, and a developing unit that develops the electrostatic latent image with a developer and generates a toner image on the image carrier. The registration mark can be formed as an electrostatic latent image on the image carrier by the print head and developed by the developing means.

  The image forming apparatus includes a patch image forming control unit that forms an electrostatic latent image of a patch image on an image carrier by a print head and develops the image by a developing unit, and a patch developed on the image carrier. It can further include density detecting means for detecting the density of the image and adjusting means for adjusting the strobe signal for register mark recording based on the density detected by the density detecting means. As a result, it is possible to adjust the strobe signal for registration mark recording based on the density of the formed patch image, thereby realizing an appropriate density as a registration mark.

  According to a third aspect of the present invention, there is provided an image forming apparatus comprising: a print head including a plurality of light emitting elements arranged along a main scanning direction; a setting unit that sets light emission times of the plurality of light emitting elements of the print head; A signal generation unit for generating a strobe signal corresponding to the light emission time set by the means, a signal circuit in which the signal generation unit is connected to a plurality of light emitting elements of the print head, and a light emission time set by the setting means And a correcting means for correcting the light quantity of a light emitting element group composed of a plurality of light emitting elements for recording registration marks on at least one end side of the print head.

  According to the image forming apparatus of the third invention, the setting means sets the light emission times of the plurality of light emitting elements of the print head, the signal generator generates the strobe signal corresponding to the set light emission time, and the print Output to a plurality of light emitting elements of the head.

  At this time, based on the light emission time set by the setting unit, the correction unit corrects the light amount of the light emitting element group including a plurality of registration mark recording light emitting elements on at least one end side of the print head. For example, if the light emission time is set short in order to change the density of the recorded image to be low, the light quantity emitted by the registration mark recording light emitting element group is corrected so as to increase.

  In this way, the amount of light emitted by the light emitting element group for register mark recording is corrected according to the set light emission time, so that the resist mark can be accurately obtained even if the density of the recorded image is changed. The concentration necessary for detection can be ensured.

  As described above, according to the image forming apparatus of the present invention, a resist mark recording strobe signal is generated for a registration mark recording light emitting element group, or according to a set emission time, Since the light amount of the light emitting element group for recording the registration mark is corrected, the density necessary for accurately detecting the registration mark can be secured even if the density of the recorded image is changed. It is done.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the first embodiment, a case where the present invention is applied to a tandem color image forming apparatus using continuous paper will be described.

  As shown in FIG. 1, the color image forming apparatus 10 according to the first exemplary embodiment of the present invention supports continuous paper (continuous paper) supported and transported by a plurality of rolls with a predetermined tension. ) 40 and print units 44C, 44M, 44Y, 44K corresponding to the respective colors of cyan (C), magenta (M), yellow (Y), and black (K) along the conveyance direction of the continuous paper 40. Are arranged in order. In the following description, unless otherwise distinguished, each print unit has the same configuration, and therefore the description corresponding to each color is omitted.

  Each print unit 44 has a photosensitive drum 46 rotatably supported by an apparatus main body frame (not shown), and around each photosensitive drum 46 is along the drum rotation direction (arrow direction in FIG. 1). A cleaner (not shown), an erase lamp (not shown), a charger (not shown), an LED print head (hereinafter referred to as “LPH”) 12, a developing device 52, and a transfer roll 54 are arranged in this order. .

  That is, after the toner remaining on the photoconductive drum 46 is removed by the cleaner, the charge on the photoconductive drum 46 is discharged by the erase lamp for charge removal, and after being charged by the charger, the LPH 12 is used to remove the charge on the photoconductive drum 46. The surface is irradiated with light to form an electrostatic latent image. The electrostatic latent image formed by the LPH 12 is developed by the developing device 52 to form a toner image, and the toner image is transferred to the continuous paper 40 by the transfer roll 54. The LPH 12 is installed so that the longitudinal direction thereof is parallel to the main scanning direction, and an electrostatic latent image for one page is formed on the photosensitive drum 46 by performing sub-scanning by each photosensitive drum 46. It is formed.

  The continuous paper 40 is wound around a roll (not shown), and the continuous paper 40 is fed from the roll to the pressure contact position of the transfer roll 54, and cyan (C), magenta (M), yellow (Y), black ( In order of K), the toner images on the photosensitive drums 46 are transferred to the continuous paper 40 by the transfer rollers 54, and the color image is transferred to the continuous paper 40. The continuous paper 40 onto which the color image has been transferred is conveyed to a fixing device 64 where the image is subjected to fixing processing (heating, pressing, etc.) and then taken up by a post-processing machine (not shown). The conveyance of the continuous paper 40 is driven by the driving roller 30 and the sub driving roller 32.

  Here, in order to detect the positional deviation of each toner image on the continuous paper 40 to which the color image has been transferred, an electrostatic latent image of a registration mark is formed at a predetermined position on the photosensitive drum 46 by each LPH 12, and the developing device The toner image of the registration mark is transferred to the continuous paper 40 by developing at 52. By detecting the registration mark of each toner image, the positional deviation of each toner image can be detected.

  Further, a CCD 26 for reading registration marks recorded on the continuous paper 40 is provided on the downstream side of the print unit 44K in the conveyance path of the continuous paper 40.

  Further, in the color image forming apparatus 10, a controller 20 for controlling each part in the apparatus, a plurality of sub print control units 22 for controlling each print unit 44, and synchronous control with respect to each sub print control unit 22. A registration mark detection unit 28 for detecting registration marks in the toner images of four colors C, M, Y, and K based on the reading result of the main print control unit 24 and the CCD 26 is provided.

  The main print control unit 24 calculates a registration mark misregistration correction value based on the four-color registration mark detection information detected by the registration mark detection unit 28 and corrects the misregistration. Data is output to each sub print control unit 22, and each sub print control unit 22 is caused to execute a positional deviation correction process. The misregistration correction process may use a conventionally known misregistration correction technique, and a description of the misregistration correction process is omitted.

  Further, the controller 20 outputs image data to each sub print control unit 22 and exchanges a command for performing print control and status information indicating a print state with the main print control unit 24.

  As shown in FIG. 2, the LPH 12 is provided with an LED array 68 in which LED chips are arranged in the main scanning direction on a substrate formed of a Pt plate or the like, and for driving the LED chips of the LED array 68. A plurality of driver ICs 70 are provided.

Further, the LPH 12 is provided with a Selfoc lens array 72 configured by arranging a plurality of gradient index rod lenses. In the SELFOC lens array 72, rod lenses are arranged so as to form an erecting equal-magnification image with a plurality of (for example, 5 to 6) rod lenses for one dot, as shown in FIG. The light emitted from each LED chip 74 is imaged on the photosensitive drum 46. Next, an electrical configuration for controlling the LPH 12 of the color image forming apparatus 10 will be described with reference to FIG.

  The sub print control unit 22 includes a print sequence control circuit 88, a print data memory 90, and strobe signal generation circuits 92A to 92C. The print data memory 90 stores image data for one page input from the controller 20. In addition, the print sequence control circuit 88 controls the print sequence of one page, and the image for one page is printed on the continuous paper 40.

  The print sequence control circuit 88 receives the page synchronization signal and the line synchronization signal from the main print control unit 24 and outputs address data to the print data memory 90. The print data memory 90 outputs the data signal of the corresponding image data. Output to LPH12.

  The print sequence control circuit 88 outputs a clock signal to the LPH 12, and outputs a load signal to the LPH 12 and the strobe signal generation circuits 92A to 92C.

  The three strobe signal generation circuits 92A to 92C have the same configuration, and all receive the load signal and output the strobe signals STRB1 to STRB3 to the LPH 12, respectively. Each of these strobe signal generation circuits 92A to 92C has a built-in strobe time register (not shown). A value corresponding to the strobe time is written into the strobe time register by the controller 20, and the strobe signal becomes high level only for the strobe time. The signal is output to the LPH 12.

  As shown in FIG. 5, the strobe signal STRB1 is input to a plurality of LED chips 74 on one end side of the printing range and on one end side of the LED array 68 corresponding to the registration mark area for printing the registration mark. The strobe signal STRB3 is input to the plurality of LED chips 74 on the other end side of the printing range and on the other end side of the LED array 68 corresponding to the registration mark area. The strobe signal STRB2 is input to a plurality of LED chips 74 of the LED array 68, which is an area between the registration mark areas at both ends and corresponding to a printing area for printing an image.

  Next, the internal configuration of the LPH 12 will be described with reference to FIG. The LPH 12 includes an LED chip group 94A in the registration mark area, a plurality of LED chip groups 94B in the printing area, an LED chip group 94C in the registration mark area, a driver IC 70A for driving the LED chip group 94A, and a plurality of LED chip groups 94B. A plurality of driver ICs 70B for driving each of them and a driver IC 70C for driving the LED chip group 94C are provided.

  A data signal from the print data memory 90 and a clock signal and a load signal from the print sequence control circuit 88 are input to each of the driver ICs 70A to 70C. Further, strobe signals STRB1 and STRB3 from strobe signal generation circuits 92A and 92C are input to driver IC 70A and driver IC 70B, respectively, and strobe signal STRB2 from strobe signal generation circuit 92B is input to driver IC 70B. .

  The driver ICs 70A to 70C receive the load signal, input a data signal by an N-bit shift register (not shown) that operates with a clock signal, and are connected to each of the driver ICs 70A to 70C by the data signal and the strobe signal. Each of the LED chips 74 of the LED chip groups 94A to 94C is driven.

  The color image forming apparatus 10 is equipped with an image density changing function, and the setting of the image density is changed by a user operation. For example, the controller 20 adjusts the light emission time of light emitted from the LPH 12 to change the image density setting.

  Next, the operation according to the first embodiment will be described. In this embodiment, a case where the image density is set low by the user will be described as an example.

  First, when the image density is set low by the user setting, the controller 20 sets a value corresponding to the strobe time corresponding to the set density in the strobe signal generation circuit 92B.

  Here, the density of the registration mark area is a constant optimum density that can accurately detect the registration mark, and a value corresponding to a predetermined strobe time is set in the strobe signal generation circuits 92A and 92C. The density change setting is not reflected in the strobe time setting of the strobe signal generation circuits 92A and 92C.

  Also, in the initial operation when the apparatus is turned on, registration mark misalignment correction processing is performed. In the misregistration correction process, in each print unit 44, the LED chip groups 94A and 94C on both ends of the LPH 12 cause the electrostatic latent images of the registration marks to be in the regions on both ends in the main scanning direction on the photosensitive drum 46 (registration marks). The toner image of the registration mark is formed on each photosensitive drum 46 by being developed by the developing device 52.

  Then, the toner images of the respective colors are superimposed on the continuous paper 40 and transferred from the photosensitive drums 46.

  When the process of transferring the registration mark to the continuous paper 40 is performed by the color image forming apparatus 10, the signals input to the driver ICs 70A to 70C change as shown in FIG.

  First, print data data signals and clock signals for the registration mark areas at both ends of the first line are input to the driver ICs 70A and 70C, respectively, and print data data signals for the print area of the first line When each of the strobe signals STRB1 to STRB3 is input after the clock signal is input to each of the driver ICs 70B and the load signal is input, the driver IC 70A determines that the LED chip is based on the strobe signals STRB1 and the data signals. Each LED chip 74 of the group 94A is driven, and the plurality of driver ICs 70B drive each LED chip 74 of the plurality of LED chip groups 94B based on the strobe signal STRB2 and the data signal, and the driver IC 70C includes the strobe signal STRB3. LED chip based on the data signal Driving each LED chip 74 of the group 94C.

  Here, since a value corresponding to a short strobe time is set in the strobe signal generating circuit 92B in order to reduce the image density, the LED chip group 94B is driven by the strobe signal STRB2 having a short strobe time, and the LED chip The light emission time 74 is shortened, and the image density in the print area is lowered.

  On the other hand, since the strobe signal generation circuits 92A and 92C are set to a value corresponding to a predetermined strobe time so as to obtain an optimum image density for accurately detecting a registration mark, the strobe time is set to a predetermined time. The LED chip groups 94A and 94C are driven by the strobe signals STRB1 and STRB3, and the light emission time of the LED chip 74 becomes a predetermined time, and the image density in the registration mark region becomes the optimum density.

  Then, the image of the resist mark is read by the CCD 26 from the area where the resist mark of the continuous paper 40 on which the resist mark is superimposed is printed, and the resist mark detector 28 detects the resist mark of each color. Then, the registration error of the registration mark is calculated by the main print control unit 24, and the misregistration correction process is performed by the sub print control unit 22, and the color image corrected for the misregistration is printed on the continuous paper 40. Is done.

  It should be noted that an existing technique may be used for the misalignment correction process, and a description regarding the misalignment correction process is omitted.

  As described above, according to the color image forming apparatus according to the first embodiment, a predetermined strobe for accurately detecting a registration mark with respect to the driver IC of the LED chip group corresponding to the registration mark area. A strobe signal having a time is generated, and a strobe signal having a strobe time corresponding to the set image density is generated for the driver IC of the LED chip group corresponding to the print area. In the case of transfer, even if the setting of the image density to be printed is changed, it is possible to ensure the optimum density necessary for accurately detecting the registration mark.

  In the above embodiment, the case where the present invention is applied to a tandem color image forming apparatus has been described as an example. However, the present invention is not limited to this, and the present invention is applied to a monochrome image forming apparatus. May be. Even in the case of a monochrome image forming apparatus, in a configuration in which roll paper or the like is conveyed pinlessly, it is preferable to detect misregistration of a registration mark and perform misregistration correction. In addition, since a monochrome image forming apparatus often prints at a considerably low density setting at the request of an end user, it is necessary to secure an optimum density necessary for accurately detecting a registration mark. Is effective.

  The strobe time of the strobe signal output to the driver IC of the LED chip group corresponding to the registration mark area is set to a predetermined strobe time and has not been changed by the image density setting. The setting may be changed separately by a setting different from the setting.

  Next, a color image forming apparatus according to the second embodiment of the present invention will be described. In addition, about the structure and operation | movement basically the same as 1st Embodiment, the same code | symbol as 1st Embodiment is attached | subjected and the description is abbreviate | omitted.

  The image forming apparatus according to the second embodiment is mainly different from the first embodiment in that a plurality of LED chip groups in the registration mark area are provided and the width of the plural types of continuous paper 40 can be handled. Is different.

  As shown in FIG. 8, the plurality of LED chips 74 of the LPH LED array 168 include an LED chip group consisting of a plurality of LED chips 74 corresponding to a registration mark region on one end side of the LED array 168, and the LED array 168. The area between the plurality of LED chip groups consisting of a plurality of LED chips 74 corresponding to the registration mark area on the end side and the registration mark areas on both ends, which is the minimum print guarantee area on the continuous paper 40 having the minimum width It is divided into a plurality of LED chip groups consisting of a plurality of LED chips 74 corresponding to the paper width printing area, and the plurality of LED chip groups corresponding to the registration mark area on the other end side includes, for example, nine registration mark small This is an LED chip group composed of a plurality of LED chips 74 corresponding to a region. Note that the nine registration mark small areas are equal to the areas where the registration marks are printed in each of the widths of the plurality of types of continuous paper 40.

  As shown in FIG. 9, the sub print control unit 122 is provided with eleven strobe signal generation circuits 92A to 92K, and outputs the strobe signals STRB1 to STRB11 to the LPH 112, respectively. A value corresponding to the strobe time is set by the controller 120 in each of the strobe signal generation circuits 92A to 92K. The strobe signal generation circuit 92B is connected to a driver IC connected to a plurality of LED chip groups corresponding to the minimum paper width printing area in order to output the strobe signal STRB2, and the strobe signal generation circuit 92B includes a user A value corresponding to the strobe time corresponding to the image density set by is set.

  The strobe signal STRB1 output from the strobe signal generation circuit 92A is input to a driver IC connected to an LED chip group composed of a plurality of LED chips 74 corresponding to the registration mark region on one end side.

  Further, each of the strobe signal generation circuits 92C to 92K is connected to a plurality of driver ICs connected to a plurality of LED chip groups including a plurality of LED chips 74 corresponding to each of the nine registration mark small regions. Each of the signal generation circuits 92C to 92K outputs each of the strobe signals STRB3 to STRB11 to the driver IC corresponding to each of the nine registration mark small regions.

  Next, a registration mark printing processing routine for printing registration marks executed in the color image forming apparatus according to the second embodiment will be described with reference to FIG.

  First, in step 200, the width information of the continuous paper 40 to be printed is acquired, and in step 202, based on the width information of the continuous paper 40, from the nine registration mark small areas on the other end side, A resist mark small region corresponding to a portion to be printed with a resist mark is selected, and a predetermined strobe signal for registration is supplied to a strobe signal generation circuit 92 connected to the driver IC of the LED chip group of the selected resist mark small region. A value corresponding to the strobe time is set. The strobe time of the registration strobe signal may be determined in advance by experimentally obtaining a time corresponding to the optimum image density for accurately detecting the registration mark.

  In step 204, based on the width information of the continuous paper 40, one of the nine registration mark subregions in the registration mark region on the other end side is selected as the portion corresponding to the portion where the registration mark is printed in step 202. A value corresponding to the strobe time of the print strobe signal is set in the strobe signal generation circuit 92 connected to the driver IC of the LED chip group in the resist mark small region corresponding to the print region. To do. For example, all the registration mark small areas between the minimum sheet width printing area and the registration mark small area corresponding to the portion where the registration mark is printed become the registration mark small area corresponding to the printing area, and correspond to this printing area. The strobe time of the print strobe signal is set in the strobe signal generation circuit 92 connected to the driver IC in the registration mark small area.

  In the next step 206, registration mark printing processing is performed, and the registration mark printing processing routine is terminated. When this printing process is executed, each signal input to the driver IC changes as shown in FIG. A case where the image density is set low will be described. For example, when the continuous paper 40 having the minimum continuous paper 40 width is to be printed, the strobe signal generation circuit 92B corresponding to the minimum paper width print area has a short strobe to reduce the image density. Since the value corresponding to the time is set, the LED chip group corresponding to the minimum paper width printing area is driven by the strobe signal STRB2 having the short strobe time, the light emission time of the LED chip 74 is shortened, and the image of the printing area is displayed. The concentration is lowered.

  On the other hand, the strobe signal generation circuits 92A, 92C to 92K are set to values corresponding to a predetermined strobe time so as to obtain an optimum image density for detecting the registration mark with high accuracy. By the strobe signals STRB1, STRB3 to STRB11, the LED chip group corresponding to a plurality of resist mark small regions including the portion where the resist mark is printed and the LED chip group corresponding to the resist mark region on one end side are driven. The light emission time becomes a predetermined time, and the image density in the registration mark area becomes the optimum density.

  As described above, according to the color image forming apparatus according to the second embodiment, the driver IC of the LED chip group in the registration mark area and the LED in the registration mark small area corresponding to the width information of the continuous paper to be printed. A strobe signal having a strobe time capable of accurately detecting a registration mark is generated for the driver IC of the chip group, and a strobe time corresponding to the set image density is set for the driver IC of the LED chip group in the print area. When the toner image is directly transferred onto the continuous paper, the optimum density necessary for accurately detecting the registration mark can be ensured even when the set image density is changed. it can.

  In addition, even when there are multiple types of continuous paper, the width of the continuous paper is different, and the registration mark is printed on these continuous papers, the registration mark is accurately detected corresponding to the continuous paper to be printed. It is possible to secure the optimum concentration necessary for the purpose.

  Next, a color image forming apparatus according to a third embodiment of the present invention will be described. In addition, about the structure and operation | movement fundamentally the same as 1st Embodiment, the same code | symbol as 1st Embodiment is attached | subjected and the description is abbreviate | omitted.

  The color image forming apparatus according to the third embodiment is different from the first embodiment in that the same strobe signal is input to all the driver ICs and the amount of light of each dot can be corrected. Mainly different.

  As shown in FIG. 12, the sub print control unit 322 includes a print sequence control circuit 388, a print data memory 90, a strobe signal generation circuit 92, and a correction data memory 390. The correction data memory 390 includes a controller. Correction data indicating the light amount correction value for each dot input from 320 is written, and the correction data memory 390 outputs a correction signal for each dot to the LPH 312.

  The print sequence control circuit 288 outputs a clock signal to the LPH 312 and outputs a load signal to the LPH 312 and the strobe signal generation circuit 92. The strobe signal generation circuit 92 outputs a strobe signal STRB common to all driver ICs to the LPH 312.

  As illustrated in FIG. 13, the LPH 312 includes a plurality of LED chip groups 294 including a plurality of LED chips, and a plurality of driver ICs 270 that drive each of the plurality of LED chip groups 294.

  Each of the driver ICs 270 receives a data signal from the print data memory 90, a clock signal and a load signal from the print sequence control circuit 288, and a strobe signal STRB from the strobe signal generation circuit 92. Further, the correction signal from the correction data memory 390 is input to the driver IC 270, and the current of the power source supplied to the LED chip 74 of the LED chip group 294 is corrected according to the correction signal for each dot, and the data signal and The LED chip 74 of the LED chip group 294 connected to the driver IC 270 is driven by the strobe signal.

  Next, a light amount adjustment processing routine for adjusting the light amount executed by the controller 320 of the color image forming apparatus according to the third embodiment will be described with reference to FIG.

  First, in step 400, the color to be adjusted is set to yellow (Y), and in step 402, it is determined whether or not the setting of the light emission time of the LPH 312 has been changed. If the user has not changed the image density setting, the light amount adjustment processing routine is terminated. On the other hand, the user changes the image density setting, and the setting of the light emission time (that is, the strobe time of the strobe signal) is changed. If so, it is determined in step 404 whether the set emission time is shorter than the standard setting.

  When the image density is set low, the set light emission time is shorter than the standard setting, and therefore, in step 406, the amount of increase in the light amount correction value is calculated based on the amount of change in the light emission time due to the setting change. For example, as shown in FIG. 15, when the light emission time is reduced by 10%, the light amount correction value is increased by 10%.

  On the other hand, when the image density is set high, since the set light emission time is longer than the standard setting, in step 408, a light amount correction value down amount is calculated based on the light emission time change amount. For example, when the light emission time is increased by 10%, the light amount correction value is decreased by 10%.

  In step 410, the dot correction data corresponding to the registration mark area is changed for the print unit of the adjustment target color based on the light amount correction value up amount or the light amount correction value down amount calculated in steps 406 and 408. In step 412, it is determined whether or not the light amount adjustment in steps 402 to 410 has been completed for all four colors Y, M, C, and K. If not, the process proceeds to step 414. The next color is set as the adjustment target color, and the process returns to step 402. On the other hand, when the light amount adjustment is completed for all four colors, the light amount adjustment processing routine is ended.

  When the density is changed by the light emission time of the LED chip 74, the strobe signal is common to all the LED chips 74, so that the density of the registration mark also decreases. However, as described above, the light amount adjustment processing routine is performed. When executed, the correction value of the light amount for each dot in the registration mark area is changed in accordance with the amount of change in the light emission time so that the density of the registration mark does not decrease even if the density setting of the printing area is changed low. Therefore, the image density in the registration mark area can be set to a density necessary for accurately detecting the registration mark.

  As described above, according to the color image forming apparatus of the third embodiment, the amount of light emitted by the LED chip group corresponding to the registration mark area is corrected according to the set emission time. Therefore, when the toner image is directly transferred onto the continuous paper, the optimum density necessary for accurately detecting the registration mark can be ensured even if the image density setting is changed.

  Next, a color image forming apparatus according to a fourth embodiment of the present invention will be described. In addition, about the structure and operation | movement fundamentally the same as 1st Embodiment, the same code | symbol as 1st Embodiment is attached | subjected and the description is abbreviate | omitted.

  The color image forming apparatus according to the fourth embodiment is mainly different from the first embodiment in that the image density of the registration mark region can be adjusted to a predetermined optimum density.

  As shown in FIG. 16, in each of the print units 544C, 544M, 544Y, and 544K of the color image forming apparatus 510 according to the fourth embodiment, a density detection sensor is provided downstream of the developing device 52 on the photosensitive drum 46. 556 is provided. The density detection sensor 556 includes a light emitting element and a light receiving element. The light receiving element detects reflected light when the registration mark passes through the detection position, and the amount of toner constituting the registration mark is determined based on the intensity of the reflected light. The detection signal shown is output to the controller 520. This toner amount is a toner adhesion amount or a toner concentration.

  Since the other configuration of the color image forming apparatus 510 is the same as that of the first embodiment, the description thereof is omitted.

  Next, a light amount adjustment processing routine according to the fourth embodiment will be described with reference to FIG. First, in step 600, the color to be adjusted is set to yellow (Y). In step 602, a variable n for identifying a plurality of light emission times to be temporarily set is set to an initial value of 1. In step 604, LPH12 Is set to the temporary light emission time n. At this time, the strobe time value corresponding to the set temporary light emission time n is set in the strobe signal generation circuit 92 so that the light emission time of the LPH 12 becomes the temporary light emission time n.

  In step 606, an electrostatic latent image of a patch image prepared in advance is formed by the LPH 12, developed by the developing device 52, and a toner image of the patch image is formed on the photosensitive drum 46. In step 608, It is determined whether n is less than a constant N (for example, N = 4) indicating the number of temporary light emission times to be set. If there is a temporary light emission time that has not been set, the process proceeds to step 610 and n is set. After incrementing, the process returns to step 604, and a toner image of the patch image is formed on the photosensitive drum 46 with a newly set temporary light emission time. When the toner image of the patch image is formed in all temporarily set light emission times, the process proceeds from step 608 to step 612.

  In step 612, the densities of all patch images formed on the photosensitive drum 46 are detected by the density detection sensor 556. In step 614, the above-described steps 602 to 602 are performed for all four colors C, M, Y, and K. It is determined whether or not the density detection process in step 612 has been completed. If there is a color for which the detection process has not been performed, the next color is set as an adjustment target color in step 616, and the process returns to step 602 to return to the next Detection processing is performed in the print unit 544 for the color to be adjusted. When the detection process is completed for all four colors, the process proceeds from step 614 to step 618.

  In step 618, for each color of C, M, Y, and K, based on the patch image density for each of the four provisional light emission times detected in step 612, the light emission time at which a standard density predetermined as the optimum density is obtained. In step 620, the controller 520 sets the strobe time value corresponding to the light emission time calculated in step 618 to the C, M, Y, and K print units 544 by the controller 520. It is set to 92C, the light emission time of the LED chip groups 94A and 94C in the registration mark area of each LPH 12 is adjusted, and the light amount adjustment processing routine is completed.

  Then, when the registration mark printing process is performed, the registration mark is formed at an optimum density, and the formed registration mark is detected, and a positional deviation correction process is performed.

  As described above, according to the color image forming apparatus of the fourth embodiment, the density of the patch image formed by each print unit is detected, and the registration mark is detected based on the detected density of the patch image. Since the light emission time for printing at the optimum density is calculated and the strobe time of the strobe signal output to the driver IC of the LED chip group corresponding to the registration mark area is adjusted, the registration mark can be printed at the optimum density.

1 is a schematic diagram illustrating a configuration of a color image forming apparatus according to a first embodiment of the present invention. It is the schematic which shows the structure of LPH which concerns on the 1st Embodiment of this invention. It is an image figure which shows a mode that the light light-emitted by the LED chip which concerns on the 1st Embodiment of this invention is imaged on a photoreceptor drum by a Selfoc lens array. 1 is a block diagram showing an electrical configuration of a color image forming apparatus according to a first embodiment of the present invention. It is an image figure which shows the position of the registration mark area | region in the printing range of the LED array which concerns on the 1st Embodiment of this invention. It is a circuit diagram which shows the electrical structure of LPH which concerns on the 1st Embodiment of this invention. It is a time chart which shows the mode of the signal input into LPH which concerns on the 1st Embodiment of this invention. It is an image figure which shows the position of the registration mark area | region in the printing range of the LED array which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the electrical constitution of the color image forming apparatus which concerns on the 2nd Embodiment of this invention. 7 is a flowchart showing the contents of a registration mark printing processing routine of a color image forming apparatus according to a second embodiment of the present invention. It is a time chart which shows the mode of the signal input into LPH which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the electrical constitution of the color image forming apparatus which concerns on the 3rd Embodiment of this invention. It is a circuit diagram which shows the electric constitution of LPH concerning the 3rd Embodiment of this invention. It is a flowchart which shows the content of the light quantity adjustment process routine of the color image forming apparatus which concerns on the 3rd Embodiment of this invention. It is a graph which shows the relationship between light emission time and the increase amount of light quantity correction amount. It is the schematic which shows the structure of the color image forming apparatus which concerns on the 4th Embodiment of this invention. It is a flowchart which shows the content of the light quantity adjustment process routine of the color image forming apparatus which concerns on the 4th Embodiment of this invention.

Explanation of symbols

10, 510 color image forming apparatus 12 LPH
20, 120, 320, 520 Controller 22, 122, 322 Sub print controller 24 Main print controller 28 Registration mark detector 40 Continuous paper 44, 544 Print unit 46 Photosensitive drum 52 Developer 68, 168 LED array 70, 270 Driver IC
74 LED chips 88, 288, 388 Print sequence control circuit 90 Print data memory 92 Strobe signal generation circuit 94, 294 LED chip group 390 Correction data memory 556 Density detection sensor STRB Strobe signal

Claims (5)

A print head comprising a plurality of light emitting elements arranged along the main scanning direction;
A first signal generator for generating a registration mark recording strobe signal; and a second signal generator for generating an image recording strobe signal, wherein the first signal generator is at least one end of the print head. A signal circuit connected to a light emitting element group composed of a plurality of light emitting elements for registration mark recording on the side, and the second signal generator connected to a light emitting element group composed of a plurality of light emitting elements for image recording;
An image forming apparatus including: A print head comprising a plurality of light emitting elements arranged along the main scanning direction;
A plurality of signal generators for generating a strobe signal, and each of the plurality of signal generators includes a plurality of light emitting element groups composed of a plurality of light emitting elements for register mark recording and a light emission composed of a plurality of light emitting elements for image recording A signal circuit connected to each of the element groups;
Based on the width information of the recording medium on which the image is formed, the signal generator connected to at least one of the plurality of light emitting element groups for register mark recording generates a strobe signal for register mark recording, Signal generation control means for generating a strobe signal for image recording in the signal generator connected to other light emitting element groups including the light emitting element group for image recording;
An image forming apparatus including: An image carrier on which an electrostatic latent image is formed on the surface by the print head;
And developing means for developing the electrostatic latent image with a developer to generate a toner image on the image carrier,
The image forming apparatus according to claim 1, wherein the registration mark is formed as an electrostatic latent image on the image carrier by the print head and developed by the developing unit. Patch image formation control means for forming an electrostatic latent image of a patch image on the image carrier by the print head and developing the image by the developing means;
Density detecting means for detecting the density of the patch image developed on the image carrier;
Adjusting means for adjusting the strobe signal for recording the registration mark based on the density detected by the density detecting means;
The image forming apparatus according to claim 3, further comprising: A print head comprising a plurality of light emitting elements arranged along the main scanning direction;
Setting means for setting light emission times of a plurality of light emitting elements of the print head;
A signal generator that generates a strobe signal corresponding to the light emission time set by the setting means, and a signal circuit that connects the signal generator to a plurality of light emitting elements of the print head;
Based on the light emission time set by the setting means, correction means for correcting the light quantity of a light emitting element group consisting of a plurality of light emitting elements for registration mark recording on at least one end side of the print head;
An image forming apparatus including:

Images