JP2000355123A - Method for recording image and image recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent lowering of image quality due to color shift by a method wherein an amount of a relative position shift in images on a plurality of photosensitive materials is limited within one line irrespective of the number of multi- beams. SOLUTION: Reverse rotation of an exposing drum is started in the engagement condition of a male blade and a female blade, then a rotary encoder is reset after the lapse of a predetermined time period. After that, a time period from when the engagement thereof is released until a tip of a plate making film 102 reaches an exposing start position in an image recording section 126 is counted to be stored in a memory. As the position is determined on an image recording position based on the stored counted value, it is possible to completely align the relative positions between punch holes of the four plate making films 102 and an image recording start position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-recording system in which an image is recorded by simultaneously scanning a plurality of light beams with an image recording means while the light beam relatively moves in the sub-scanning direction of the photosensitive material. The present invention relates to an image recording method and an image recording apparatus using a beam.

[0002]

2. Description of the Related Art
When an image is recorded on a photosensitive lithographic printing plate such as a PS plate, exposure is performed in a state where a plate making film is overlaid on the photosensitive lithographic printing plate.

A plate making film is generated by recording an image by an image recording device called a film setter and developing the image.

In this film setter, a magazine for winding and storing a long plate-making film in a layered manner is set.

[0005] The exposure drum is rotated at a predetermined speed by the driving force of the driving means, and this is a sub-scanning movement. An image recording device is provided in a radial direction of a peripheral surface of the exposure drum held in close contact.

[0006] In an image recording apparatus, a plurality of light beams emitted from a laser are swung in the axial direction of an exposure drum by a plurality of optical systems (main scanning by a multi-beam method). As a result, the main scanning is repeated while the plurality of light beams are sub-scanned on the plate making film. Since the light beam is on / off controlled (or duty controlled) based on image information, a predetermined image is recorded on the plate making film.

[0007] The plate-making film on which the image has been recorded is guided from the film setter by being guided along a usual transport path, and is sent to the developing device in the next step.

[0008] Here, when the printed matter of the photosensitive lithographic printing plate is a color image, C (cyan), M
It is necessary to prepare a photosensitive lithographic printing plate for each of the four color components (magenta), Y (yellow), and K (black) (that is, four photosensitive lithographic printing plates).

[0009] On the four photosensitive lithographic printing plates, images are recorded so that the relative positions of the images coincide with each other.
By superimposing the four images, a printed matter of a full-color image can be obtained.

Since the film for making a stencil continuously moves in the sub-scanning direction, the first image recording start position (the swing width of the main scanning) after detecting the leading end (main scanning start line position) of the film for making a stencil. From the initial position). At this time, there is no correlation between the sub-scanning movement of the plate making film and the scanning of the main scanning light beam.

For this reason, an image of each color is recorded with a shift of at most about one sub-scan. What is one sub-scan
The greater the number of multi-beams, the greater the width. For example, when exposing 96 beams / mm with six beams, the beam pitch is about 10 μm, and thus the maximum deviation is 60 μm. The maximum permissible limit for printed matter is about 100 μm. If the deviation at the writing position occupies 60% or more, the deviation due to other factors such as the deviation of the transport system or the position of the positioning punch hole will occur. Is almost unacceptable, resulting in color misregistration and deterioration in image quality.

In consideration of the above facts, the present invention can keep the relative positional deviation amount of an image between a plurality of photosensitive materials within one line pitch regardless of the number of multi-beams, and deteriorates image quality due to color misregistration. It is an object of the present invention to provide an image recording method and apparatus capable of preventing the occurrence of an image.

[0013]

According to a first aspect of the present invention, one image data is divided into at least two colors, and each of the image data divided into the at least two colors is used as a sub-material of the photosensitive material. An image recording method using a multi-beam in which an image is recorded by simultaneously main scanning a plurality of light beams on an image by an image recording means while the light beam relatively moves with respect to the scanning direction. In each photosensitive material corresponding to the image, based on the amount of misalignment of the photosensitive material in a sub-scanning direction from a predetermined reference position to a main scanning start line position, from the beginning of a plurality of light beams during the first main scanning. It is characterized in that blank raster lines of non-image data are set in order.

According to a second aspect of the present invention, one image data is divided into at least two colors, and the light beam is relatively moved in the sub-scanning direction of the photosensitive material.
An image recording method using a multi-beam in which an image is recorded by simultaneously main scanning a plurality of light beams on an image by an image recording means, wherein a predetermined reference position in each photosensitive material corresponding to the same image is obtained. The amount of positional deviation of the photosensitive material in the sub-scanning direction up to the main scanning start line position is determined, and the deviation of the photosensitive material at the main scanning start line position where the amount of positional deviation is largest is one line pitch at the maximum. During the main scanning of another photosensitive material, the number of blank raster lines is set in order from the top in the sub-scanning direction of the photosensitive material, and the beginning of the line excluding the number of blank raster lines is set as the apparent main scanning start line position. Features.

According to a third aspect of the present invention, C (cyan), M (magenta), Y (yellow) and B
Based on each image data color-separated into K (black), the light beam relatively moves with respect to the sub-scanning direction of the photosensitive material, and N light beams (N
Is an image recording apparatus using a multi-beam for recording an image by simultaneously performing main scanning of two or more light beams at the same time, wherein the light beam moves relatively to the sub-scanning direction of the photosensitive material. A photosensitive material detecting means provided on a transport path (on a photosensitive material transport path or a light beam transport path) for detecting a relative main scanning start line position between the photosensitive material and the light beam; and starting image recording in the main scanning. A main scanning start position detecting means for detecting a position, and a signal from the photosensitive material detecting means for detecting the position after the photosensitive material and the light beam reach a relative main scanning start line position, and Main scanning start control means for starting the main scanning by controlling the image recording means when a signal from the means is received, and main scanning starting from a relative main scanning start line position of the photosensitive material and the light beam. Until the start, the calculation means for calculating the relative movement amount L of the photosensitive material and the light beam, and the movement amount L calculated by the calculation means with respect to one known sub-scanning movement amount W in advance. Based on the ratio R (0 ≦ R <1), the smaller the ratio R, the smaller the number (N−1) of the number of light beams by one at the time of the first main scanning by the image recording means. In many cases, there is provided blank raster line setting means for setting blank raster lines in order from the top in the sub-scanning direction of the photosensitive material.

According to the first aspect of the present invention, when one image is formed by superimposing images recorded on a photosensitive material, the positioning thereof is important. In addition, the relative positional relationship between the photosensitive material and the image must also be adjusted. Here, when an image is recorded by repeating main scanning while the light beam relatively moves in the sub-scanning direction of the photosensitive material, the writing line position may be shifted between the photosensitive materials. That is, since the time required for the relative position of the photosensitive material and the light beam to reach from the predetermined reference position (for example, the tip position) on the photosensitive material to the main scanning start line position has no correlation with each other, the number of multi-beams is large. The greater the number, the greater the shift in the sub-scanning direction.

For this reason, blank raster lines of non-image data are set in order from the head of a plurality of light beams at the time of the first main scanning, based on the positional shift amount of the photosensitive material in the sub-scanning direction. That is, by providing a line in which nothing is apparently recorded, the beginning of the image is shifted to the rear side in the sub-scanning direction of the photosensitive material by that amount, so that it is possible to match the photosensitive material with the largest shift amount.

According to the second aspect of the present invention, the amount of displacement of the photosensitive material in the sub-scanning direction from a predetermined reference position (for example, the leading end position) to the main scanning start line position is obtained.

The image recording start position is determined in such a manner that the optical system for performing the main scanning uses a polygon mirror, a resonant mirror, or the like.
Because the surface that mechanically reflects the light beam is swung in the main scanning direction, immediately after this optical system has passed the initial position, if the photosensitive material and the light beam have reached the relative main scanning start line position, Next, the user must wait until the optical system reaches the initial position. On the other hand, immediately after the photosensitive material and the light beam reach the relative main scanning start line position, if the optical system is at the initial position, it is possible to start recording an image with almost no time lag.

If the main scanning start timings differ greatly as described above, the sub-scanning is continued by that amount, and the relative positions of the images on the photosensitive material do not match.

Therefore, for the photosensitive material at the main scanning start line position where the amount of displacement is the largest, the number of blank raster lines is set in order from the top in the sub-scanning direction of the photosensitive material at the time of main scanning of another photosensitive material. The head of the line excluding the number of blank raster lines is regarded as an apparent image recording start line.
As a result, since the displacement is a maximum of one line pitch, the displacement can be set within an allowable range. The invention according to claim 3 provides a C, which is necessary for forming a so-called full-color image,
The present invention is an apparatus for recording an image by applying a multi-beam (N light beams) to four photosensitive materials for each color of M, Y, and BK. , The main scanning start line position is detected, and then the main recording start detecting means detects the image recording start position. Therefore, the arithmetic means, between the relative main scanning start line position of the photosensitive material and the light beam until the main scanning is started,
Calculate the relative movement amount L of the photosensitive material and the light beam,
The ratio R of the movement amount L to the one sub-scanning movement amount W (0 ≦
R <1) is determined. Based on the ratio R, the smaller the ratio R is at the time of the first main scanning, the more the blank raster lines are set from the head of the photosensitive material in the sub-scanning direction (blank raster line setting means). The number of blank raster lines is set as a limit of one less than the number N of light beams.

In this case, in the case of the best timing, the first (N-1) main scanning lines are wasted. As a result, a high-quality image without color shift can be obtained.

[0023]

FIG. 1 is a schematic structural view of a film setter 100 as an image processing apparatus for a plate making film according to the present invention.

The plate making film 102 is wound around a reel 104 in a long state, and is stored in a magazine 106. The magazine 106 can be loaded at a predetermined position of the apparatus main body 108.

The plate making film 102 pulled out of the magazine 106 is sandwiched between a pair of transport rollers 110A and 110B as a feed roller 110.

In the feed roller 110, one of the transport rollers 110A (or 110B) receives the driving force from the motor 112 via a speed change means (not shown), and the plate making film 102 is held between the transport rollers 110A and 110B. As a result, the paper is sequentially pulled out of the magazine 106 and sent to the exposure drum 114.

The exposure drum 114 receives the driving force of a motor 116 through a speed change means (not shown), and is driven to rotate at the same linear speed as the linear speed of the plate making film 102 by the feed roller 110. .

Nip rollers 118 and 120 are provided at two different positions on the peripheral surface of the exposure drum 114, respectively.

The surface of one nip roller 118 is made of metal.
The plate making film 102 fed from the feed roller 110 is inserted between the feed roller 110 and the feed roller 14 and is sandwiched. The plate-making film 102 after being sandwiched
Is wound around the peripheral surface of the exposure drum 114. This wrapping continues to a position where the other nip roller 120 and the exposure drum 114 are nipped.

The other nip roller 120 has a rubber surface, and the other nip roller 120 and the exposure drum 1
14, the plate making film 102 is peeled off from the exposure drum 114, and is sent to a normal transport path NR configured by arranging a plurality of pairs of transport rollers 122.

The motors 112 and 116 are driven to rotate forward and reverse based on a control signal from a controller 124. That is, when the exposure drum 114 normally rotates in the normal direction, the plate making film 102 is received from the feed roller 110 and is sent to the normal transport path NR. ing.

The controller 124 also adjusts the driving torque of a motor 116 for rotating the exposure drum 114. That is, it is controlled to rotate at a relatively high torque during forward rotation and to rotate at a relatively low torque during reverse rotation.

The high-torque side is not particularly limited, but the low-torque side is used when the stencil film 102 whose conveyance is restricted is nipped and conveyed (reverse feed) by the nip rollers 118 and 120.
It is set to such an extent that the plate making film 102 is tensioned by a predetermined tension and is not damaged.

An image recording section 126 is provided above the region of the exposure drum 114 around which the plate making film 102 is wound.

As shown in FIG. 2, the image recording unit 126
Helium neon laser 128 (hereinafter simply referred to as laser 1
28).

The controller 124 stores image information, and controls an AOM (acoustic optical element) 132 based on the image information to output a plurality of light beams (blink).
Is controlled.

The light beam output from the laser 128 is transmitted through a reflection mirror 130 to an AOM (acoustic optical element).
The light beam is divided into a plurality of light beams (six light beams in the present embodiment) by the 132 and is input to the resonance scanner 134 via the reflection mirror 133. In the resonance scanner 134, the six light beams have a function of oscillating in the main scanning direction of the plate making film 102. The light beam oscillated in the main scanning direction is transmitted by the scanning lens 136 and the two Exposure drum 1 via reflection mirrors 137 and 139
14 is scanned. Here, the six light beams are arranged in the sub-scanning direction on the plate making film 102, and are recorded for six main scanning lines in one main scan.

At this time, the exposure drum 114 is rotating at a constant speed, and the rotation causes the plate making film 102 to move in the sub-scanning direction. Therefore, the plate making film 10
In step 2, subscanning is performed so that six main scanning lines are recorded, and by repeating this, an image based on image information can be recorded on the plate making film 102.

In the vicinity of the exposure drum 114, a leading end detection sensor 115 for detecting the leading end of the plate making film 102 in the transport direction is provided.
It is determined that the recording position has been reached when the leading end of the plate making film 102 is detected.

Therefore, after the leading edge detection sensor 115 detects the leading edge of the plate making film 102, an image is recorded from the time when the resonance scanner 134 reaches the initial position.

A cutter section 138 is provided in the middle of the normal transport path NR so that the plate making film 102 on which the image on the exposure drum 114 is recorded can be cut at predetermined lengths. It has become. The cut sheet-shaped plate making film 102 is discharged from the film setter 100 and sent to a developing device (not shown) which is a subsequent process.

Here, the film setter 100 of the present embodiment is provided with a punch unit 140 for punching a positioning punch hole.

The punch unit 140 is provided on the downstream side of the exposure drum 114 and at the end of a branch path DR branched from the normal transport path NR.

The branch path DR is connected to the other nip roller 1.
Plate-making film 102 formed by an exposure drum 20 and an exposure drum 114
Is a starting point, and at this starting point, it is slightly downward in FIG.
(Approximately 45 ° in the lower left direction).

Here, whether the plate making film 102 is guided to the normal transport path NR or the branch path DR is determined by the necessity of punch holes, and the movable guide section 1
By moving the position 42, the actual plate making film 102 is guided in a desired direction.

As shown in FIG. 3A, the movable guide plate 142 is provided at a branch point between the normal transport path NR and the branch path DR with a point 150 rotatably supported at one end. By rotating the shaft 150,
One of the transport routes can be selected.

As another structure of the movable guide portion 142, as shown in FIG.
4, 146, and 148. The three rollers 144, 146, 148 are in contact with each other in the vertical direction. The central roller 146 has a driving force for rotating forward and backward.

Here, when the plate making film 102 is to be guided to the normal transport path NR, the center roller 14
6 is rotated counterclockwise. As a result, the plate making film 102 is sandwiched between the upper roller 144 and the center roller 146, and is guided and conveyed to the normal conveyance path NR. When the leading edge of the plate making film 102 goes below the center roller 146, the lower roller 1
With the rotation of 48, it is pushed up toward the central roller 146.

On the other hand, the plate making film 102 is transferred to the branch road DR.
, The center roller 146 is rotated clockwise. As a result, the plate making film 102
Is sandwiched between the lower roller 148 and the central roller 146, and is guided and conveyed to the branch path DR. When the leading end of the film 102 for making a plate goes above the center roller 146, it is pushed down toward the center roller 146 by the rotation of the upper roller 144.

The above three rollers 144, 146, 148
Alternatively, the guide plate may be movable, and the transport path may be switched as in point switching.

Exposure drum 114 and punch unit 140
A guide plate 152 is provided in a branch path DR between the punch unit 1 and the punch unit 1.
It can transport up to 40.

The punch unit 140 includes a driver 154
Is connected to the controller 124 via the. The punch unit 140 is provided with a male blade and a female blade. The male blade is driven by the driver 154 with the plate making film 102 interposed between the male blade and the female blade. By moving it and fitting it to the female blade, a punch hole of a predetermined shape (for example, circular) is formed.

The punch unit 140 is provided with a tip detection sensor 156, which is controlled by the tip detection sensor 156 so that a male blade is fitted when the tip of the plate making film 102 is detected. I have.

The state in which the male blade is fitted to the female blade is maintained for a predetermined time, during which the plate making film 102 is reversely fed by the reverse rotation of the exposure drum 114 and
4 and the looseness generated between the fitting portion of the male blade and the female blade is eliminated, and the tension state is established. In this case, since the reverse rotation of the exposure drum 114 has a low torque as described above, the plate making film 102 does not break.

Here, a rotary encoder 158 is attached to the exposure drum 114, and the output signal is supplied to the controller 124. The controller 124 resets the output signal from the rotary encoder 158 when a predetermined time has elapsed after the start of the reverse rotation of the exposure drum 114, and then releases the male blade and the female blade to thereby control the leading edge of the plate making film 102. The section counts until the section reaches the exposure start position in the image recording section 126.

Referring to FIG. 4, in step 200, an image recording mode is input from an operation panel (not shown) or the like.
Set. This recording mode determines whether the image is a monochrome image such as a black and white image or a color image. In the case of a monotone image, the recording mode is constituted by one plate making film 102, and in the case of a color image, Is composed of four plate making films 102 for each color of CMYK.

In the next step 202, the plate making film 102 is pulled out of the magazine 106,
In steps 04 and 206, the feed roller 110 is driven forward and the exposure drum 114 is driven forward.

In the next step 208, it is determined whether or not punch holes are required. That is, in the case of a color image, in order to determine whether or not punch holes are required for positioning the four plate making films 102, this determination depends on the recording mode set in the step 200.

If it is determined in step 208 that punch holes need to be formed, it is determined that a color image is to be recorded.
In step 210, the movable guide portion 142 is set to the branch road DR guide side.

As a result, the plate making film 102, which is nipped and conveyed by the feed roller 110 and is wound around a part of the peripheral surface of the exposure drum 114 by the nip rollers 118 and 120, is connected to the branch path DR where the punch unit 140 is provided. Transported to the end of

In step 212, the punch unit 14
It is determined whether or not the leading edge of the plate making film 102 has been detected by the leading edge detection sensor 156 provided at 0. If the determination is affirmative, the process proceeds to step 214 to stop driving the feed roller 110 and the exposure drum 114. I do.

In the next step 216, the male blade is fitted to the female blade to form a punch hole, and a punch hole is formed. In the present embodiment, the male blade maintains a state fitted to the female blade.

In the next step 218, the exposure drum 11
4 is driven in reverse. At this time, since the male blade is in a state of being inserted into the punch hole, even if the plate-making film 102 is loosened, the slack is eliminated and a tension state is set.

Here, in this embodiment, since the driving torque at the time of reverse rotation driving of the exposure drum 114 is set to a low torque, the male blade does not damage the periphery of the punch hole at the time of the tension, so that it can be used for plate making. The predetermined tension state of the film 102 is maintained.

When it is determined in the next step 220 that the predetermined time has elapsed, in step 224, the count value of the rotary encoder 158 is reset. That is, the plate making film 102 is
When a predetermined tension state is established between the punch unit 4 and the punch unit 140, the count value is reset, so that the reset can always be performed under the same condition (the same position).

In the next step 226, the exposure drum 11
4 is stopped, and the engagement between the male blade and the female blade that have been inserted into and maintained in the punch holes is released (the punching operation is released). In step 228, the exposure drum 114 and the feed roller 110 are released.
Is driven in reverse.

When the plate making film 102 is fed backward after the punching operation is released, the rotary encoder 158 attached to the exposure drum 114 is counted from the reset state. The plate making film 102 is fed backward until the count value reaches a predetermined value.

If it is determined in step 230 that the count value of the rotary encoder 158 has reached a predetermined value,
The flow shifts to step 232, where the reverse drive of the feed roller 110 and the exposure drum 114 is stopped, and the flow shifts to step 234.

If it is determined in step 208 that punching of punch holes is unnecessary, that is, if the image is a monotone image, the process proceeds from step 208 to step 234. In step 234, the movable guide portion is set to the normal conveyance path guide side, and the process proceeds to image recording control shown in FIG.

As shown in FIG. 5, in step 250, the feed roller 110 and the exposure drum 114 are driven to rotate in the normal direction. Then, in step 252, the leading edge of the plate making film 102 is detected by the leading end detection sensor 115 near the exposure drum 114. It is determined whether or not it has been detected.

If an affirmative determination is made in step 252,
It is determined that the leading end of the plate making film 102 has reached the prescribed position, and an image recording process is executed in step 254. In this image recording process, the resonance scanner 1
The main scanning of the multi-beam (six beams) is started in synchronization with a signal indicating that 34 has reached the initial position. Since the sub-scan is always performed by the rotation driving of the exposure drum 114, the main scan is sequentially repeated,
Recording of one image is completed. The image recording process will be described later with reference to FIGS.

After passing the predetermined length (sub-scanning) after the image recording is completed (step 256), that is, when the predetermined amount of the stencil film 102 is conveyed, the feed roller 1
The driving of the exposure drum 114 and the exposure drum 114 is stopped (step 258), and in step 260, the cutter unit 138 is operated to cut the plate making film 102 into a sheet of one image. Cut sheet-shaped plate making film 102
Is conveyed by the pair of conveying rollers 122 and discharged from the film setter 100.

On the other hand, the remaining plate-making film (long side) 1
02 is the feed roller 110 in step 262.
And the exposure drum 114 is driven to rotate in the reverse direction, whereby the sheet is fed backward.

In step 264, it is determined whether or not the count value of the rotary encoder 158 accompanying the reverse feed has reached a predetermined value. If the determination is affirmative, it is determined that the same position as in step 230 in FIG. 4 has been reached. In step 266, the feed roller 110 and the exposure drum 1
The reverse rotation drive of No. 14 is stopped.

In the next step 268, it is determined whether or not to continue the process. If the process is to be continued, the process returns to step 200 in FIG. 4, and if not, the process ends.

FIG. 6 shows a subroutine of the image recording process.

In step 270, the feed roller 110
Then, the exposure drum 114 is driven to rotate forward, and then, in step 272, it is determined whether or not the main scanning start line position has been reached.

If an affirmative determination is made in step 272, an image recording start instruction signal is output (step 274).

In the next step 276, the moving amount L and the one sub-scanning width W (the sub-scanning length moving during one main scanning) with respect to the time difference between the image recording start instruction signal and the signal that the resonant scanner has reached the initial position. ) Is calculated (L / W = R), and then in step 278, the number of blank raster lines S from the upper limit (the uppermost line) of the multi-beam is set according to the ratio R.

At step 280, image data is read based on the set blank raster line number S.

Here, when the timing is the best (when the time difference between the image recording start instruction signal and the signal when the resonant scanner reaches the initial position is the shortest) and when the timing is the worst (the image recording start instruction signal and the When the time difference from the signal at which the resonant scanner reaches the initial position is the longest), a large deviation of the writing start position occurs. In the present embodiment in which the number S of multi-beams is 6, this shift is shifted by 6 beams.

The width of the main scanning line is about 10 μm, and the allowable range of color misregistration as a printed matter is limited to 100 μm. If the shift at the start of recording occupies most of the allowable range, another factor (four plate making films 1
02) easily exceeds the allowable range, resulting in a decrease in the finished image.

Therefore, in the present embodiment, the ratio R (=
(L / W), the number of lines in the normal line is set to only the lower limit (lowest line), and the other lines are set as blank raster lines. Upper line)
Is controlled so as to be shifted by a maximum of one line.

As shown in FIG. 7, pattern A is a case where the resonant scanner 134 reaches the initial position immediately after the plate making film 102 reaches the main scanning start line position, and is the most appropriate positional relationship. For this reason, it is possible to write six multi-beams from the main scanning start line position of the plate making film 102. However, in this embodiment, in this case, five multi-beams are used as blank raster lines, An image is recorded only on the bottom line (one line).

Patterns B to E show the case where the time from when the plate making film 102 reaches the main scanning start line position to when the resonant scanner 134 reaches the initial position is divided step by step. The number S of raster lines is determined. That is, the smaller the time difference between the image recording start instruction signal and the signal that the resonant scanner has reached the initial position, the smaller the number of blank raster lines S
The longer the time difference between the image recording start instruction signal and the signal that the resonant scanner has reached the initial position,
The number S of blank raster lines is reduced.

On the other hand, the pattern F is the film 10 for plate making.
2 is a case where the resonant scanner 134 reaches the initial position immediately before reaching the main scanning start line position, the time until the next writing start is longest, and the plate making film 102 is transported the longest in the sub-scanning direction. This is the area where
In this case, the image is completely recorded with a delay of substantially one main scanning time.

That is, the pattern A is set to the maximum value (N-1) of the number of blank raster lines S, and thereafter, areas of patterns B to F are set, and the number of blank raster lines S
Is reduced one by one and an image is recorded based on the image data only in the remaining lines, so that even if the image recording is performed in any pattern, it is possible to suppress the displacement to a maximum of one line.

In step 282 shown in FIG. 6, the main scanning is started. In the plate making film 102, the blank raster line number S is determined by one of the patterns A to F, and the first main scanning is performed. Is performed, the shift between the four plate making films 102 in the case of a color image is a maximum of one line width, and no further shift occurs. As a result, it is possible to reduce deterioration in image quality such as color misregistration. In addition, here, as much as the shift is reduced,
It is possible to allow a certain degree of tolerance for other factors (such as the positional deviation of the punch holes), and it is possible to effectively use the allowable deviation of 100 μm.

The image is recorded as the same number of raster lines by a plurality of light beams for each main scan, and ends when all the raster lines for one screen are recorded. At this time, in the last main scan, not all of the plurality of light beams become image data. In the last main scan, only the required number of light beams are on / off controlled by image data, but the remaining light beams are set as blank raster lines of non-image data. In step 284, it is determined whether or not one image has been recorded. If the determination is affirmative, this routine ends.

In the image processing apparatus for a stencil film shown in FIG. 1, the stencil film is conveyed by a feed roller or a roller sandwiched between exposure drums so that the light beam is relatively directed in the sub-scanning direction of the photosensitive material. This is an example of a method of moving to.

On the other hand, the photosensitive material is fixed on the inner surface of the exposure drum, and the light beam moves in the main scanning direction and the sub-scanning direction to record one screen (inner drum method), or the photosensitive material is wound around the exposure drum. The present invention can also be applied to a system (outer drum system) in which the exposure drum is rotated at high speed (main scanning) together with the photosensitive material in a state where the light beam moves in the sub-scanning direction to record one screen.

[0092]

As described above, according to the image recording method and the image recording apparatus of the present invention, regardless of the number of multi-beams, the relative positional deviation amount of an image between a plurality of photosensitive materials is kept within one line pitch. This has an excellent effect that the image quality can be prevented from lowering due to color misregistration.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a film setter according to the present embodiment.

FIG. 2 is a perspective view of an image exposure unit.

3A and 3B are schematic diagrams of a movable guide unit, where FIG. 3A is an example applied to the present embodiment, and FIG. 3B is a modified example.

FIG. 4 is a flowchart showing a feed control routine for a plate making film.

FIG. 5 is an image recording control routine on a plate making film.

FIG. 6 is a subroutine showing details at the time of image recording.

FIG. 7 is a diagram illustrating a plurality of patterns for determining the number S of blank raster lines at the beginning of main scanning.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 film setter 102 plate-making film 110 feed roller 114 exposure drum 115 tip detection sensor (photosensitive material detection unit) 124 controller (main scanning start control unit, calculation unit, blank raster line setting unit) 126 image recording unit 134 resonance scanner ( Main scanning start position detecting means)

Claims (3)

[Claims] An image data is divided into at least two colors, and a light beam relatively moves in a sub-scanning direction of a photosensitive material based on each image data divided into at least two colors. An image recording method using a multi-beam in which an image is recorded by simultaneously scanning a plurality of light beams in an image by an image recording means, wherein a predetermined standard for each photosensitive material corresponding to the same image is used. Based on the amount of displacement of the photosensitive material in the sub-scanning direction from the position to the main scanning start line position, blank raster lines of non-image data are set in order from the head of the plurality of light beams during the first main scanning. Characteristic image recording method. 2. A method according to claim 1, wherein one image data is divided into at least two colors, and a plurality of light beams are formed by an image recording means while the light beams relatively move in the sub-scanning direction of the photosensitive material. An image recording method using a multi-beam in which an image is recorded by simultaneously performing main scanning, wherein a sub-scanning of the photosensitive material from a predetermined reference position to a main scanning start line position in each photosensitive material corresponding to the same image. In the main scanning of another photosensitive material, the amount of misalignment in the main scanning direction is determined so that the photosensitive material having the largest amount of misalignment is the main scanning start line position and has a maximum of one line pitch. An image in which the number of blank raster lines is set in order from the top in the sub-scanning direction, and the head of the line excluding the number of blank raster lines is set as an apparent main scanning start line position. Recording method. 3. Based on image data obtained by color-separating one image into C (cyan), M (magenta), Y (yellow), and BK (black), each of the light-sensitive materials in a sub-scanning direction. An image recording apparatus using a multi-beam in which N (N is an integer of two or more) light beams is simultaneously scanned by an image recording means while an image beam is relatively moved to record an image. A photosensitive material and a light beam are provided on a transport path on which a light beam relatively moves with respect to a sub-scanning direction of the photosensitive material (on a photosensitive material transport path or a light beam transport path); A photosensitive material detecting means for detecting a start line position; a main scanning start position detecting means for detecting an image recording start position in the main scanning; and a signal from the photosensitive material detecting means, the photosensitive material and the light beam Main scanning start control means for controlling the image recording means to start main scanning after reaching a relative main scanning start line position and upon receiving a signal from the main scanning start position detecting means; Calculating means for calculating a relative movement amount L of the photosensitive material and the light beam during a period from the relative main scanning start line position of the photosensitive material and the light beam until the main scanning is started; Based on the ratio R (0 ≦ R <1) of the movement amount L calculated by the calculation means to the one sub-scanning movement amount W
At the time of the first main scanning by the image recording means, the smaller the ratio R is, the smaller the number (N-1) of the number of light beams is than the number N of the light beams, the larger the ratio becomes. A blank raster line setting unit for setting a line.