JP2008195020A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily detect an overlapping region, and to minimize density unevenness of a seam of a divided scanning region by easily detecting an overlapped region, when a plurality of laser exposure sections scan respective divided parts an exposure region in a main scanning direction. <P>SOLUTION: An image forming apparatus carries out scanning while three laser exposure sections 11, 12 and 13 scan respective divided parts of a main scanning region, and forms an image on a piece P1 of photosensitive material in units of dots by intensity modulating the exposure beam of each laser exposure section for every piece of pixel data constituting an image. The image forming apparatus is provided with: an image processing section 203 and the respective laser exposure sections, which print on photosensitive material a continuous test pattern which has an unsaturated specified exposure quantity, from the three laser exposure sections, and also has a partly overlapped region in the both ends of respectively divided scanning parts; a colorimeter 5 measuring the density for every dot of the test pattern image printed on the photosensitive material; and an overlapped region determination section 201 detecting dot positions in the overlapped region from the distribution of density information for every measured dot. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention scans a predetermined scanning area by sharing the exposure beams of a plurality of laser exposure units, and the exposure beam of each laser exposure unit is intensity-modulated for each pixel data constituting an image, so that a photosensitive material in dot units. The present invention relates to an image forming apparatus that forms an image thereon.

  By exposing and scanning the photosensitive material by deflecting the laser beam from the laser emission source using a polygon mirror, and modulating the laser beam with image data such as a photograph using an AOM (acousto-optic conversion element). 2. Description of the Related Art An image forming apparatus including an exposure device that forms a photographic image on a photosensitive material is known. Among the exposure apparatuses, the laser emission source, in particular, has a large temperature characteristic of the laser output power. Therefore, a temperature adjusting means using a Peltier element or the like has been provided.

  In recent years, there has been a demand for creating a relatively large photographic print such as a poster using such an image forming apparatus. In other words, it is necessary to scan the entire region in the width direction of the wide photosensitive material with a laser beam. To that end, a method for scanning the laser beam deflected by the polygon mirror in a wider region or a scanning region using a plurality of exposure apparatuses. A method of sharing can be considered. In the former method, it is necessary to increase the distance from the polygon mirror to the exposure position on the photosensitive material, leading to an increase in the size of the apparatus in the optical path length direction. Furthermore, since the fθ lens is required to have optical accuracy, if a large size lens is used, it will become expensive and costly.

Patent Documents 1 and 2 describe the latter image forming apparatus employing a plurality of exposure apparatuses. In this image forming apparatus, the main scanning area is scanned by two or three exposure apparatuses. With this configuration, there is an advantage that the size of the apparatus in the optical path length direction is hardly increased.
Japanese Patent Laid-Open No. 3-98066 JP 2006-264220 A

  In an aspect using a plurality of exposure apparatuses as in Patent Documents 1 and 2, while it is necessary to accurately share the main scanning area with the scanning area of the laser beam of each exposure apparatus, Since it is not easy to expose the image with the laser beam from the exposure apparatus, an overlap area is provided in a partial area at the end of the shared area, and the laser beam of the exposure apparatus on both sides of the overlap area is used in this overlap area. A method of exposing an image is employed. However, each exposure apparatus has individual differences, and considering the attachment error etc., there is no guarantee that the overlapping area will be constant. In this case, discontinuity occurs at the joint of the image in the overlapping area, and the image in the sub-scanning direction There may be uneven stripes.

  The present invention has been made in view of the above. When an exposure area in the main scanning direction is shared by a plurality of laser exposure units, an overlapping area is easily detected, and density unevenness in a joint of the shared scanning area is suppressed as much as possible. An object of the present invention is to provide an image forming apparatus that can perform such a process.

  According to the first aspect of the present invention, a predetermined scanning region is scanned by sharing with exposure beams of a plurality of laser exposure units, and the intensity of the exposure beam of each laser exposure unit is modulated for each pixel data constituting an image. In the image forming apparatus for forming an image on a photosensitive material in dot units, the plurality of laser exposure units have a predetermined amount of unsaturated exposure, and a partial region at the end of each scanning region to be shared is overlapped. Further, a test print means for printing a continuous test pattern on the photosensitive material, a density measuring means for measuring the density of the image of the test pattern printed on the photosensitive material for each dot, and density information for each measured dot And an overlapping portion detecting means for detecting the dot position of the overlapping region from the distribution.

According to this configuration, a predetermined scanning area corresponding to the width dimension of the photosensitive material is scanned by sharing with the exposure beams from the plurality of laser exposure units. In each laser exposure unit, the exposure beam is intensity-modulated for each pixel data constituting the image, and the image is exposed to each shared area, thereby one image for the entire predetermined scanning area. Is formed. Further, the light intensity corresponding to a predetermined amount of unsaturated exposure from each laser exposure unit so that a partial region at the end of each scanning region to be shared overlaps a partial region at the end of the adjacent laser light. Test pattern image data is output and printed on a photosensitive material. Since the test pattern image is continuous in the width direction and is at an unsaturated level, the overlapping portion is printed in an overlapping manner with the adjacent test pattern image, compared to the density of the test pattern image in the non-overlapping area. It will be relatively high. Therefore,
The density of the test pattern image printed by the density measuring means installed in the image forming apparatus or prepared separately is measured for each dot, and the distribution of density information for each dot measured by the overlapping part detecting means Thus, the position of the dot in the overlapping area, that is, the overlapping area in the sharing area in dot units is detected. Once the detected overlapping area is identified, the laser light from the laser exposure unit adjacent to the overlapping area is distributed in intensity (shading correction) in actual image printing, so that a superimposed image forming process can be performed. Alternatively, it may be used for information for completely dividing adjacent shared areas (for example, dividing by the dot position at the center of the overlapping area), and various usage modes of the overlapping area are conceivable.

  Therefore, even if there are individual differences and mounting errors between the laser exposure units, the overlapping region detection operation is performed individually at the manufacturing stage or the initial adjustment stage, or periodically or as needed. Thus, it is possible to print an image appropriately on the overlapping area, and the occurrence of density unevenness due to discontinuity of the image at the joints (overlapping areas) of the scanning ranges handled by the plurality of laser exposure units is suppressed. .

  According to the first aspect of the present invention, even if there are individual differences and mounting errors between the laser exposure units, the image forming apparatus is individually manufactured or initially adjusted, or periodically or as needed. By performing the overlapping area detection operation, it is possible to properly print an image on the overlapping area, and as a result, due to the discontinuity of the image at the joints (overlapping areas) of each scanning range handled by multiple laser exposure units Occurrence of uneven density can be suppressed.

  FIG. 1 is an overall configuration diagram of a photographic processing apparatus 1 showing an embodiment of an image forming apparatus according to the present invention. The photographic processing device 1 is a photographic photosensitive material based on, for example, image data obtained by capturing a photographic image of each frame of a film with a scanner (not shown), or image data transferred from a computer or an external memory. A laser exposure unit 10 that exposes the photosensitive material P to form a predetermined image on the photosensitive material P is provided. The laser exposure unit 10 is disposed at a position facing the exposure position on the conveyor 2 that conveys the photosensitive material P in the interior 1 b of the housing 1 a of the photographic processing apparatus 1. The conveyor (photosensitive material conveyance unit) 2 includes a plurality of conveyance roller pairs 2a and guide rails 2b arranged along the conveyance direction.

  In addition, a plurality of magazines, for example, magazines 3 and 4 that respectively store the photosensitive material P wound in a roll shape are exchangeably loaded on the upper surface of the housing 1a. In order to detect the type of the photosensitive material P stored in the magazines 3 and 4, the sensors 3a and 4a are opposed to the upper surface of the housing 1a with the magazines 3 and 4 and the magazines 3 and 4 loaded, respectively. Is arranged. In the sensors 3a and 4a, for example, a plurality of magnets for expressing the type of photosensitive material (mainly width size) by a predetermined bit are arranged on the magazines 3 and 4 side so as to form a bit code, and on the housing 1a side. The magnetic sensor unit for recognizing the bit code is provided. Further, a colorimeter 5 as a density measuring means is provided on the upper surface of the housing 1a for reading a test chart after exposure, which will be described later, and measuring the density for each color of R, G, B (each light). Yes.

  The housing 1a and the magazines 3 and 4 are dark boxes, and the leading ends of the photosensitive materials P are drawn from the magazines 3 and 4 to the interior 1b of the housing 1a. The photosensitive material P is cut into a predetermined size (length) by a cutter 6 provided in the interior 1b of the housing 1a. Hereinafter, the photosensitive material P cut to a predetermined length is referred to as a photosensitive material piece P1. The photosensitive material piece P1 is conveyed further downstream from the exposure position to the developing unit 7 by the conveyor 2 in the interior 1b of the housing 1a. Note that the magazines 3 and 4 and the conveyor 2 are photosensitive materials of different sizes. In this embodiment, the normal conveying system, that is, the mode in which the center in the width direction of the photosensitive material piece P1 coincides with the center of the conveying path regardless of the size. It is configured to be conveyed on the basis of (center reference).

  The developing unit 7 has a plurality of tanks 7a, 7b, 7c, and 7d for storing a developing solution, a fixing solution, a bleaching solution, and a stabilizing solution, respectively. When the photosensitive material piece P1 exposed by the laser exposure unit 10 is conveyed through the developing unit 7, the latent image is developed, and an image is formed on the photosensitive surface of the photosensitive material piece P1. The photosensitive material piece P1 on which the image is formed is dried by the drying unit 8 and discharged from the inside 1b of the housing 1a. The discharged photosensitive material piece P1 is stacked on a sorter 9 provided on the upper surface of the housing 1a.

  In addition to the control unit 20 provided in the housing 1a, the photographic processing apparatus 1 includes a monitor 31, such as a CRT or LCD, a keyboard 32, and a mouse 33, which are connected to the control unit 20, and includes a microcomputer or the like inside. A terminal unit 30 having a control unit is provided. By these, the user inputs orders and print information, a predetermined command (command) related to the printing operation, and confirms input information such as information related to development of the photosensitive material P. Is. The print information includes the width size of the photosensitive material P to be printed. The terminal unit 30 may be provided separately from the housing 1a of the photo processing apparatus 1 or may be provided integrally with the housing 1a.

  FIG. 2 is a diagram showing an example of the configuration of the laser exposure unit. In the present embodiment, the laser exposure unit 10 is composed of three laser exposure units 11, 12, and 13, and each is individually accommodated in a housing having a box shape, for example. The three laser exposure units 11, 12, and 13 have the same configuration. Hereinafter, the laser exposure unit 11 will be described as a representative.

  The laser exposure unit 11 has three laser light sources 110R, 110G, and 110B that output laser light in the R (red), G (green), and B (blue) wavelength bands, which are the three primary colors of light, each having a unique wavelength. Is provided.

  Further, the laser exposure unit 11 has a light modulator (such as an acousto-optic modulator) (hereinafter referred to as an acousto-optic modulator) via a condenser lens on each optical path of each laser beam from the laser light sources 110R, 110G, and 110B. 111R, 111G, and 111B (referred to as AOM) are disposed, and mirrors 112R, 112G, and 112B are disposed on the downstream side thereof via a slit plate. The mirrors 112R, 112G, 112B and the mirror 113 reflect the laser light emitted from the laser light sources 110R, 110G, and 110B in the direction of the polygon mirror 114.

  The mirror 112R is a total reflection mirror, and reflects the red laser light output from the laser light source 110R to the mirror 112G side. The mirror 112G is a half mirror that transmits red laser light and reflects green laser light output from the laser light source 110G to the mirror 112B side. The mirror 112B is a half mirror that transmits the red laser light and the green laser light and reflects the blue laser light output from the laser light source 110B to the mirror 113 side. The three laser beams are superimposed (combined) by the mirror 112B.

  The polygon mirror 114 is rotated at a constant speed (for example, 10,000 to 20,000 rpm) in a direction indicated by an arrow by a polygon driver 115 such as a pulse motor, and reflects laser light in a predetermined range. An fθ lens 116 is provided in front of the polygon mirror 114, and the polygon mirror 114 and the fθ lens 116 deflect the laser beam on the photosensitive material piece P1 at a constant speed in the main scanning direction indicated by the arrow A. The photosensitive material piece P1 is conveyed by the conveyor 2 in a direction perpendicular to the paper surface of FIG. Therefore, the photosensitive surface of the photosensitive material piece P1 is exposed in the width direction by scanning with the light-modulated laser beam.

  Similarly, the laser exposure units 12 and 13 scan the light-modulated laser beam in a predetermined region in the width direction of the photosensitive material piece P1. The optical axes are set so that the scanning of the laser beams from the laser exposure units 11, 12, 13 is in the same line (or zigzag), and the scanning ranges partially overlap on the photosensitive material piece P1. (See FIG. 2).

  Further, a mirror 118 for reflecting the laser beam toward the synchronous sensor 117 is provided on the emission side of the fθ lens 116 and on the upstream side in the main scanning direction closest to the image exposure region. The synchronization sensor 117 is configured by a light receiving element such as a photodiode (PD), for example, and outputs a synchronization signal for starting image exposure by receiving, for example, red laser light or all three colors.

  The laser exposure unit 11 is set so that the intensity of each laser beam is constant. The intensity of each laser beam emitted from the laser light sources 110R, 110G, and 110B is modulated by the AOMs 111R, 111G, and 111B, respectively, according to the density gradation of each component of R, G, and B constituting the image data. The

  The photographic processing apparatus 1 includes a main control unit 200 including a CPU for controlling the overall operation. The main control unit 200 includes an image processing unit 203, a timing control unit 240 for controlling input / output timing of image data, and a polygon clock generator 250a inside, and a rotation control instruction to the polygon driver 114 (124, 134). A polygon control unit 250 is connected.

  The laser driving unit 110 is connected between the main control unit 200 and the laser light sources 110R, 110G, and 110B, and maintains the emission intensity of the laser beam output from the laser light sources 110R, 110G, and 110B at a predetermined constant level. It is something to control.

  As shown in FIG. 3, the image processing unit 203 includes an exposure area determination unit 2031 and an image processing unit 2032. The image processing unit 203 divides the image data of each color to be printed in the main scanning direction and a necessary level for each image data. Temporary storage of image data after tone adjustment correction processing and necessary correction processing is performed. The image data is, for example, one photographic image data, and is two-dimensional image data having a plurality of pixel data constituting one line for each RGB color. The image processing unit 203 receives the clock data from the timing control unit 240 for the image data of each color for each line in units of lines, or sequentially transfers the image data for one line one pixel at a time to the image transfer unit 210, in this case the line. Output to the memories 211R, 211G, 211B. The line memories 211R, 211G, and 211B receive the clock signal from the timing control unit 240, serially store the image data for one line of each color, and start the laser beam based on the detection signal from the synchronization sensor 117. Are sequentially read out pixel by pixel in synchronism with the exposure operation to the photosensitive material.

  The AOM drivers 212R, 212G, and 212B are controlled to modulate the intensity of the laser light of each color that passes through the AOMs 111R, 111G, and 111B in accordance with the gradation density data of the pixel data of each color. The AOMs 111R, 111G, and 111B are configured by unillustrated acoustooptic elements, ultrasonic transducers, light modulation element driving units, and the like. When the ultrasonic transducer is driven by the drive signal supplied from the light modulation element driving unit, a periodic refractive index change that functions as a diffraction grating is generated inside the acoustooptic device. When the laser light is incident on the AOMs 111R, 111G, and 111B, the laser light is diffracted by Bragg reflection by the diffraction grating generated by the ultrasonic vibration, and is emitted as zero-order diffracted light and first-order diffracted light. The 0th-order diffracted light is shielded by the wall of the slit plate, and the 1st-order diffracted light passes through the slit plate and enters the mirrors 112R, 112G, and 112B.

  When the timing controller 240 detects from the detection signal from the paper position sensor 2c that the leading end of the photosensitive material piece P1 conveyed by the conveyor 2 has been conveyed to the position (exposure start position) at which photo printing is started, exposure is performed. Start operation. Further, the timing control unit 240 detects the pulse period of the rotation pulse from the rotation amount detection means such as a rotary encoder (not shown) from the polygon driver 115, and the pulse period is stable, that is, the polygon mirror 115 is at a constant speed. It is to confirm that it is rotating. Further, after confirming that the detection signal from the position sensor is input and the polygon mirror 115 is rotating at a constant speed, the timing control unit 240 detects each detection signal from the synchronous sensors 117, 127, 137 (this embodiment). (In this embodiment, every time a laser beam of R color is detected), it is transferred to the line memories 211R to 211B, 221R to 221B, 231R to 231B and the AOM drivers 212R to 212B, 222R to 222B, 232R to 232B at a predetermined timing. Output a start signal. The image processing unit 203 sequentially reads out pixel signals for one line to the line memories 211R to 211B, 221R to 221B, and 231R to 231B each time a transfer start signal is output.

  FIG. 3 is a functional block diagram of the overlapping area determination or image processing part. As described above, the image input unit 400 is assumed to be a device that optically reads an image on a film, or a network unit that acquires image data from an external memory or the like. An image storage unit 401 is a memory unit that temporarily stores a captured image. The test pattern data storage unit 301 is image data for test printing, and is saturated when a predetermined density gradation, for example, a gradation range of “0” to “255” is printed twice. Even if it is saturated (for example, “100”), or even if it is saturated, a continuous line image of each color having an unsaturated gradation (for example, “200”) whose density difference from the non-saturated region can be sufficiently identified by the colorimeter 5 It is.

  The colorimeter 5 is a sensor that can measure at least the density, and is a mechanism (slider structure or rotation of a ball screw) that can move in one direction (here, the main scanning direction) and a pulse motor that moves at a constant speed. It is configured. Alternatively, the position in the main scanning direction, that is, the measurement position can be detected with a resolution of 1 dot by counting the number of pulses of the pulse motor with a counter. As a result, density information is obtained in units of each dot of the test pattern image printed on the photosensitive material piece P1. Note that a line sensor that does not require movement may be employed as the colorimeter 5.

  The overlap area determination unit 201 obtains a correction position, that is, an overlap area, from the density data for each dot measured by the colorimeter 5, and a color measurement data acquisition unit 2011, a correction position calculation unit 2012, and a correction position setting unit 2013. Is provided. In the colorimetric data acquisition unit 2011, the exposure area determination unit 2031 receives an instruction from the terminal 30, reads the test pattern data in the test pattern data storage unit 501, and exposes it via the laser exposure units 11, 12, and 13. For the test pattern image of the photosensitive material piece P1, density data for each dot of the test pattern image measured by the colorimeter 5 is fetched and temporarily stored.

  The correction position calculation unit 2012 compares the density data for each dot captured by the colorimetric data acquisition unit 2011 with the density level of the test pattern data instructed to be printed by the exposure area determination unit 2031 to determine whether the overlapping area is non-overlapping. This is to determine whether it is an area. For example, if the measured density data level is substantially the same as the density level of the test pattern data (the difference between the two is within a predetermined range), it is determined as a non-overlapping area, and if it is greater than a predetermined value, it is determined as an overlapping area. In the above example, if the test pattern density value is “100” and the measured density value is “80” to “120” (difference is plus or minus 20), the areas are substantially the same as the non-overlapping areas. "Or a higher value, for example," 150 "or more, it is determined as an overlapping region.

  FIG. 4 is a diagram showing the density state of the test pattern image exposed in the test mode. In FIG. 4, from the polygon mirrors 115, 125, 135 (see FIG. 2), within the range of the sharing area set in advance so that the sharing areas adjacent to each other sufficiently overlap each other, for example, the density value “ It is assumed that scanning is performed with a test pattern of 100 "and printing is performed on the photosensitive material piece P1. Here, each sharing area is P11, P12, and P13. For example, in the case of the photosensitive material piece P1 having a width of 36 inches, an overlapping area corresponding to a predetermined small dimension is added to 12 inches (actually, as can be seen from FIG. 4, main scanning of the overlapping areas Q1 and Q2 is performed. That is, a half of the direction width is added). On the photosensitive material piece P1, an overlapping area Q1 between the sharing area P11 and the sharing area P12 adjacent to each other is exposed as a density “200”, and an overlapping area Q2 between the sharing area P12 and the sharing area P13 adjacent to each other is exposed. Is exposed as a density “200”, and the other range is a density “100”. The main scanning direction positions at both ends of the overlapping area Q1 are q11 and q12, and the main scanning direction positions at both ends of the overlapping area Q2 are q21 and q22. The correction position calculation unit 2012 identifies the dot q11 to q12 and the dots q21 to q22 as overlapping regions from the sequential comparison of density data of adjacent dots as described above.

  The correction position setting unit 2013 uses the information of the obtained overlapping region Q1 (dots q11 to q12) and the overlapping region Q2 (dots q21 to q22), and the laser exposure units 11 and 12 that share these overlapping regions Q1 and Q2. , 13 are grasped, and the shared area and overlapping area of each laser exposure unit 11, 12, 13 are newly set as dot positions using the information on the dot positions. . This new overlapping area setting, that is, the correction position setting, is a mode in which the adjacent laser beams are superimposed to expose the image, and the shading correction value in dot units for both laser beams is set individually. is doing. For example, as shown in FIG. 5, when the relationship between the laser exposure units 11 and 12 is viewed now (the relationship between the laser exposure units 12 and 13 is the same), the shading correction characteristic SD1 is given to the laser exposure unit 11. The shading correction characteristic SD2 is set for the laser exposure unit 12. These characteristics SD1 and SD2 are set such that the added value of the shading correction value of the corresponding dot that is the print position in the laser exposure units 11 and 12 is “1”. A predetermined scanning range is set in each of the laser exposure units 11, 12, and 13 so that the overlapping area is surely generated when the test pattern is printed. The overlapping area set after this test is It may be the same as that at the time of the test, or rather, it is preferable to set a new range so as to be a predetermined narrow range due to the nature of the overlapping region. When a predetermined overlapping area narrower than the test time is set, the dot positions of other areas are further based on the normal shading correction process, that is, a test pattern for shading correction of a predetermined level (even if the same as the test time) It is only necessary to set a shading correction value according to the ratio between the predetermined level and the exposure amount on the photosensitive material P obtained by scanning (good).

  The image processing unit 203 uses, as pixel position information, predetermined divided areas that the laser exposure units 11, 12, and 13 share in the main scanning direction for each image to be printed input from the image input unit 4. An exposure area determination unit 2031 to be stored, a shading correction value storage unit 2032 in which a shading correction value for each dot in each divided area including an overlapping area is stored, and a divided image corresponding to each image according to the shading correction value The image processing unit 2033 temporarily stores each image data after correcting (multiplying) the density value of the data and performing a predetermined gamma correction in a memory portion corresponding to each divided area. The exposure area determination unit 2031 receives an instruction from the terminal 30, reads the test pattern data from the test pattern data storage unit 501 to the laser exposure units 11, 12, and 13 and exposes the photosensitive material piece P1. is there.

  Although the photosensitive material piece P1 having a size of 36 inches has been described with reference to FIG. 4, there are various sizes of photosensitive materials. For example, assuming a photosensitive material having a size of 16 inches, the overlapping area Q1, the center standard, is assumed. Image printing is performed on both sides of Q2. On the other hand, the overlapping regions Q1 and Q2 are processes that use both shading correction values by the adjacent laser exposure units 11, 12, and 12, 13, and therefore, it is preferable to reproduce the image using the non-overlapping regions as much as possible. . Therefore, instead of the center-based transport method, a mode in which the transport method using the one end side in the width direction as a reference (one-end reference) is adopted for the conveyor 2 can be considered. In this way, if the above-mentioned 16-inch photosensitive material is assumed to be the left end reference in FIG. 4, the printing process can be performed in the shared areas P11 and P12, and the overlapping area Q2 need not be used. The shift of the photosensitive material piece P1 toward one end in the width direction is such that the placement position of the magazines 3 and 4 placed on the upper portion of the housing 1a is changed in accordance with the width size of the photosensitive material P to be stored. A shift mechanism may be employed between the cutter 6 of the conveyor 2 and the exposure position. Alternatively, a magazine in which the photosensitive material P is stored at one end in the width direction in the magazines 3 and 4 may be configured regardless of the size of the photosensitive material P.

  As the shift mechanism, a pressing member capable of appearing and retracting in the conveyance path from one side in the width direction is arranged between the conveyance roller pair 2a arranged at a predetermined interval along the conveyance path of the conveyor 2, and the pressing member It is possible to adopt a structure in which the drive unit is made to appear and disappear in the width direction. According to this configuration, the photosensitive material piece P1 cut by the cutter 6 is shifted to the one end side in the width direction by the pressing member at a position until it reaches the exposure position. A contact piece may be provided on the one end side, and the photosensitive material piece P1 may be shifted until the side of the shifted photosensitive material piece P1 contacts the contact side. In this way, at the exposure position, image printing on the photosensitive material piece P1 is always performed on the basis of one end. Further, as another aspect of the shift mechanism, a part of the conveyor 2 has an independent structure portion that is slidable in the width direction between the cutter 6 and the exposure position, and is at the center reference at the position of the cutter 6. Before the photosensitive material piece P1 is conveyed to the exposure position, it is shifted to one end side in the width direction at this independent structure portion, and the shifted photosensitive material piece P1 is continuously conveyed toward the exposure position. It is also possible. The shift amount may be determined based on detection signals from the sensors 3a and 4a that detect the type (size) of the photosensitive material P stored in the magazines 3 and 4.

  In the mode in which the photosensitive material piece P1 is conveyed and exposed on the basis of one end, the image processing in the image processing unit 203 is performed so that the image data in the main scanning direction is line memory 211R-211B, 221R-221B, 231R so as to meet the one end reference. To 231B. For example, when printing on the 16-inch photosensitive material piece P1, only image data transfer processing to the line memories 211R to 211B and 221R to 221B is required.

  Alternatively, from the minimum size up to 23 inches, the printing operation in the overlapping area is not performed as much as possible as one end reference. On the other hand, when printing on the photosensitive material piece P1 of a larger size, the overlapping area Q1, Since the printing operation is always performed in Q2, a method of switching the conveyance method according to the size may be used so that the center reference is used as it is.

  In addition, the following aspects are employable for this invention. The line memory has two lines, and one line of data from the image processing unit is alternately transferred to each line, and the transfer is performed from the opposite one line side. It is preferable in terms of efficiency. Further, the number of laser exposure units to be shared is not limited to three, but may be two, or may be a predetermined number of four or more, and any type can be adopted. Further, the laser exposure unit 10 may have a mode in which the laser exposure units are housed in a common housing.

  As another calculation method for the correction position calculation unit 2012, the density data captured in the colorimetric data acquisition unit 2011 is calculated for each dot, for example, by comparing the density data of adjacent dots in order from one side. And detecting or specifying a dot whose density greatly changes compared to the density of the previous dot, that is, a dot that becomes higher and a dot that becomes lower.

1 is an overall configuration diagram of a photographic processing apparatus showing an embodiment of an image forming apparatus according to the present invention. It is a figure which shows an example of a structure of a laser exposure unit. It is a functional block diagram of an overlap area determination thru | or image processing part. It is a figure which shows the condition of the density | concentration of the test pattern image exposed by test mode. It is a figure which shows an example of the shading correction value with respect to an overlapping area | region.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photo processing apparatus 2 Conveyor 5 Colorimeter 10 Laser exposure unit
11, 12, 13 Laser exposure unit 110 Laser drive unit 110R-110B, 120R-120B, 130R-130B Laser light source 111R-111B, 121R-121B, 131R-131B AOM
211R to 211B, 221R to 221B, 231R to 231B Line memory 212R to 212B, 222R to 222B, 232R to 232B AOM driver 114, 124, 134 Polygon mirror 201 Overlapping area determination unit 2011 Colorimetric data acquisition unit 2012 Correction position calculation unit 2013 Correction position setting unit 203 Image processing unit 2031 Exposure region determination unit 2032 Shading correction value storage unit 2033 Image processing unit 210 Image transfer unit P1 Photosensitive material piece P11, P12, P13 Sharing region Q1, Q2 Overlapping region

Claims (1)

A predetermined scanning area is scanned by sharing with exposure beams of a plurality of laser exposure units, and the exposure beam of each laser exposure unit is intensity-modulated for each pixel data constituting the image, so that an image is formed on the photosensitive material in dot units. In the image forming apparatus to be formed,
Test print means for printing a continuous test pattern on the photosensitive material, which has a predetermined amount of unsaturated exposure from the plurality of laser exposure units, and which overlaps a partial area at the end of each scanning area to be shared; A density measuring means for measuring the density of a test pattern image printed on the photosensitive material for each dot, and an overlapping portion detecting means for detecting the dot position of the overlapping area from the distribution of density information for each measured dot An image forming apparatus.

Images