JP3488189B2 - Multicolor printing apparatus and method of recording images on printing plate in multicolor printing apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor printing apparatus provided with an image recording apparatus for recording an image on a printing plate on a plate cylinder based on image data, and an image recording method.

[0002]

2. Description of the Related Art Recently, an image recording apparatus for recording an image on a printing plate based on digital image data, a so-called CTP.
A multi-color printing device in which a (Computer-To-Plate) device is incorporated in a machine has been put to practical use, for example, Japanese Patent Laid-Open No. 10-272.
It is disclosed in Japanese Laid-Open Patent Publication No. 756. Such a multi-color printing apparatus is called a digital printing machine, and is suitable for high-mix low-volume printing that requires a short working time because a printed matter can be obtained directly from image data, and the plate making process is automated. Therefore, the selling point is that even an unskilled operator can easily handle it.

[0003]

By the way, in a general multicolor printing apparatus including the above-mentioned digital printing machine, the printing paper has a mechanism in which the printing paper is pressed by the number of colors between the impression cylinder and the blanket cylinder. ing. In such a multicolor printing apparatus, the printing paper tends to stretch for each color to be printed, although it is slight. Therefore, there is a problem in that the positions of the first printed image and the second printed image do not match. In particular, since the printing paper is squeezed while rotating between the impression cylinder and the blanket cylinder in a state where the leading edge of the printing paper is clamped, the printing paper tends to expand more on the trailing end side of the printing paper than on the leading end side.

In order to solve the above problems, in a conventional multicolor printing apparatus which uses a printing plate produced by closely printing an original film or the like, a method of changing the position of an image to be made based on the color of the printing plate is used. Had adopted.

For example, FIG. 12 is an explanatory view showing an example of imposing eight page images p1 to p8 on the printing plate PL. In the figure, the original arrangement position of the page images p5 to p8 corresponding to the paper tail side of the printing paper is the position shown by the dotted line, but in consideration of the elongation of the printing paper, as shown by the solid line on the printing plate PL. The paper is arranged in advance in the direction in which the paper extends. By arranging the images so that the images are shifted by the color plates in this way, it is possible to reduce color misregistration due to paper elongation.
However, since the above method merely shifts the position of the image in a simulated manner, it cannot accurately correct the partial stretch of the image due to the stretch of the paper.

Further, if the imposition of a plurality of images as described above is possible, the position can be corrected for each image, but in the case of one image arranged over almost the entire printing plate PL, each part is corrected. It is not possible to finely adjust the position. In the case of such a single image, it is conceivable that the dimensions of the entire image are scaled to align the images. However, since the amount of expansion of the printing paper is different on the leading edge side and the trailing edge side, it is not possible to accurately cope with such a method of varying the magnification of the entire image at a constant magnification.

The present invention has been made to solve the above-mentioned problems, and multicolor printing provided with an image recording apparatus capable of correcting color misregistration of an image due to expansion of printing paper in a multicolor printing apparatus. An object is to provide an apparatus and an image recording method.

[0008]

Means for Solving the Problems The invention described in claim 1 is a multi-color printing apparatus for performing multi-color printing, the coercive printing plate
A predetermined light that is turned on / off at a predetermined timing according to predetermined image data while rotating the held plate cylinder.
Scan the printing plate with a laser beam emitted from a source
An image recording device for recording an image on the printing plate by
A plurality of stages on which an image is recorded by the image recording means.
In which inks of different colors are supplied to the printing plate
A supply means and the plurality of printing plates for one printing sheet
Printed materials can be printed by transferring the ink images above.
To obtain the printing means and the mutually different ones formed on the printed matter.
For each print image of different colors
A first upper end in a first direction corresponding to the direction of rotation;
Measured with at least the first lower end as the measurement point
Also, the mark in a second direction corresponding to the axial direction of the plate cylinder
Based on the size of the printed image, the image recording means can
Reduce the variable magnification when recording the image on each plate.
At least to the second upper edge and the second lower edge of the image.
And the calculating means for calculating
Storage means for storing, the image recording means for calculating
The image in the axial direction based on the scaled magnification
The size of the image is temporary or stepwise along the rotation direction.
The image is magnified and recorded so that
To collect.

[0009] According to a second aspect of the invention, in the multi-color printing apparatus according to claim 1, wherein the image recording means, said
The scanning speed of the laser beam is changed according to the magnification .
Thus, the image is magnified and recorded .

[0010] According to a third aspect of the invention, in the multi-color printing apparatus according to claim 1, wherein the image recording means, said
The image is scaled by changing the on / off timing of the laser beam according to the scaling ratio.
The feature is that it is recorded .

[0011] According to a fourth aspect of the invention, in the multi-color printing apparatus according to any one of claims 1 to 3, wherein the variable
Double magnification is applied to the second upper end and the second lower end.
And the second upper end of the image and
The scaling ratio between the second lower end and the second lower end is calculated by the second
Magnification of the upper end and the second lower end of the
Is determined by an interpolation calculation based on . The invention described in claim 5 is the multicolor mark according to claim 4.
In the printing apparatus, the first upper end portion and the first lower end portion
The print image giving a first positioning mark pointing to
The second person further records it together with the image on the printing plate.
The size of the printed image in the direction of the first upper end and the first
Between the first positioning marks at the lower end of the
Is measured as. Claim 6
The invention according to claim 1 is the multicolor mark according to any one of claims 1 to 5.
In the printing apparatus, the image recording unit is configured to prevent the printed image from smelling.
Second position indicating the intermediate portion in the first direction
The printing plate with a plate image giving a decision mark together with the image
On the printed image, and measure each printed image of different color.
Determined in the first direction in the printed image
Upper spacing, which is the spacing between the first upper end and the intermediate portion
And a lower space, which is the space between the lower end and the middle part.
On the basis of the image recording means
Of the different colors when recording the image
With the ratio of the upper side magnification, which is the ratio of the upper spacing, and the lower spacing,
Further equipped with means for calculating each lower magnification
The image recording means is based on the upper and lower magnifications.
To correct the size of the image in the rotation direction.
An image is recorded on a printing plate.

[0012] The invention according to claim 7, in the multi-color printing apparatus according to claim 6, wherein the image recording section, the upper
Corrects the dimension in the sub-scanning direction by changing the rotation speed of the plate cylinder based on the side and lower magnifications.
To, characterized in that.

[0013]

The invention according to claim 8 does not include claim 1.
In multi-color printing apparatus according to any one of to 7, printing order
Is calculated in correspondence with .

[0015]

The invention according to claim 9 is a multicolor printing apparatus.
The method of recording images on the printing plate in
Depending on the specified image data while rotating the held plate cylinder
Predetermined light that is on / off controlled at predetermined timing
Scan the printing plate with a laser beam emitted from a source
An image recording device for recording an image on the printing plate by
And a plurality of images recorded in the image recording step.
The inks of different colors are supplied to the printing plates of
Ink supply process and the above-mentioned multiple printings on one printing paper
Printed matter by transferring the ink images on the plate respectively
And a printing step for obtaining the
For each of the print images of different colors, the plate cylinder in the print image
At least in the first direction corresponding to the direction of rotation of
1 is measured with the upper end and the first lower end as measurement points.
Also, the mark in a second direction corresponding to the axial direction of the plate cylinder
Based on the size of the printed image, it is
Magnification scaling when recording the image on each of several printing plates
A rate of at least a second top edge and a second bottom edge of the image
Calculation step for calculating a part and the calculated scaling
A step of storing a magnification, and the image recording step.
In the above, based on the calculated scaling ratio,
The size of the image in the axial direction is temporary along the rotation direction.
The image is scaled so that it is different from time to time or stepwise.
The feature is that it is recorded .

[0017]

The invention described in claim 1 0, in an image recording method to a printing plate in a multi-color printing apparatus according to claim 9, in the image recording step, the zooming magnification
Therefore, by changing the scanning speed of the laser beam,
The image is magnified and recorded .

[0019] The invention according to claim 1 1, claim 10
In the method of recording an image on a printing plate in the multicolor printing apparatus according to the item 1, in the image recording step,
According to the on / off timing of the laser beam
The image is scaled and recorded by changing
It is characterized by

[0020]

[0021]

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic side view showing an example of a multicolor printing apparatus according to the present invention, and FIG. 2 is a block diagram showing a control unit that controls the entire multicolor printing apparatus.

As shown in FIG. 1, this multicolor printing apparatus is
As a printing mechanism, first and second plate cylinders 1 and 2 for holding a printing plate, first and second blanket cylinders 3 and 4 for transferring an ink image from each plate cylinder, and a printing sheet are held. And the impression cylinder 5 that contacts both blanket cylinders 3 and 4
A feed cylinder 6 and a discharge cylinder 7 for supplying or discharging printing paper to and from the impression cylinder 5, and the first and second plate cylinders 1 and 2
A dampening water supply means 8 and an ink supply means 9 for supplying dampening water or ink to the upper printing plate, a paper feed section 10 for sequentially supplying the stacked unprinted printing papers, and a printed printing paper A sheet discharging unit 11 that sequentially stacks the sheets is provided.

On the other hand, this multicolor printing apparatus has a printing plate supply unit 12 as a plate making mechanism for supplying an unexposed printing plate to the first and second plate cylinders 1 and 2, and a printing on the plate cylinder. An image recording unit 13 for recording an image on a plate, a developing unit 14 for developing a printing plate on which an image is recorded, and a printing plate discharging unit 15 for discharging a used printing plate are provided.

Further, this multicolor printing apparatus picks up an image on a printed printing paper and measures the amount of positional deviation of the printed image, and, as shown in FIG. 2,
The image pickup unit 16 is provided for controlling each unit of the multicolor printing apparatus.
And a control unit 17 for performing image processing on the image obtained in 1. The details of each unit will be described below.

The first plate cylinder 1 is configured to be movable between a first printing position shown by a solid line in FIG. 1 and an image recording position shown by a chain double-dashed line by a plate cylinder driving mechanism (not shown). Similarly, the second plate cylinder 2 is also configured to be movable between a second printing position shown by a solid line in FIG. 1 and an image recording position shown by a chain double-dashed line by a plate cylinder driving mechanism (not shown). ing. That is, the first and second plate cylinders 1 and 2 are
When performing a printing operation, they are arranged at the first or second printing positions, respectively, and when performing a plate making operation, they are alternately arranged at the image recording positions and the plate making process of the printing plates is performed on each plate cylinder. .

Each of the first plate cylinder 1 and the second plate cylinder 2 has a peripheral surface capable of holding a printing plate for two colors, and the printing plates of the respective colors face each other by 180 degrees. Two sets of gripping means (not shown) for fixing in position are provided. FIG. 9 is an explanatory diagram showing an example in which two printing plates each having one printing area are provided on the plate cylinders 1 and 2. As shown in the drawing, a print area PR for recording an image is arranged on the printing plate, and in each print area PR, an image IM for each color and positioning marks R1 to R4 for cutting, for example, arranged at four corners thereof are arranged. And are recorded.

In the above embodiment, two printing plates each having one printing area are mounted on the plate cylinder, but one printing plate having two printing areas arranged in series is mounted. You may do it. Further, for example, a predetermined polymer or the like may be applied and cured to form the surface of the plate cylinder itself as a printing plate surface.

Returning to FIG. 1, the first blanket cylinder 3
Is configured to rotate in contact with the first plate cylinder 1 at the first printing position, and the second blanket cylinder 4
Similarly for the second printing cylinder 2 at the second printing position.
It is configured to abut and rotate. The first and second blanket cylinders 3 and 4 have the same diameter as the first and second plate cylinders 1 and 2, and are blankets capable of transferring ink images of two colors from each plate cylinder. It is attached to the peripheral surface.

The impression cylinder 5 includes the first and second plate cylinders 1,
It has a diameter of 1/2 of 2, and is configured to rotate in contact with both the first and second blanket cylinders 3, 4. The impression cylinder 5 is provided with gripping means (not shown) capable of holding one sheet of printing paper having a size corresponding to the printing area on the printing plate. The gripping means can open and close at a predetermined timing by an opening / closing mechanism (not shown) to hold the printing paper.

The paper feed cylinder 6 and the paper discharge cylinder 7 have the same diameter as the impression cylinder 5, and are provided with gripping means (not shown) similar to the gripping means provided in the pressure cylinder 5. The gripping means of the paper feed cylinder 6 and the paper discharge cylinder 7 is arranged so that the printing paper can be delivered and received in synchronization with the gripping means of the impression cylinder 5.

The first and second plate cylinders 1 and 2 arranged at the first and second printing positions, the first and second blanket cylinders 3 and 4, the impression cylinder 5, and the paper feed cylinder. 6 and the discharge cylinder 7, each of the cylinders is provided with a drive gear (not shown) having the same size as the diameter of each cylinder at the cylinder end, and the gears are meshed between the cylinders contacting each other. . Therefore, by driving this gear by a print driving motor (not shown), the cylinders can be rotationally driven in synchronization.

In the multicolor printer of this embodiment,
Since the plate cylinders 1 and 2 and the blanket cylinders 3 and 4 have twice the perimeter of the impression cylinder 5, the impression cylinder makes two revolutions each time the plate cylinders 1 and 2 and the blanket cylinders 3 and 4 make one revolution. Therefore, when the impression cylinder 5 makes two rotations while holding the printing paper, multicolor printing of a total of 4 colors can be performed from each of the first and second plate cylinders 1 and 2.

Two sets of dampening water supply means 8 are arranged for each of the plate cylinders 1 and 2 at the first and second printing positions. The dampening water can be supplied selectively. This dampening water supply means 8 is composed of a water dam that stores dampening water and a dampening water roller group that pumps up the dampening water in the water dam and delivers it to the printing plate surface. abutting roller plate surface, it has been configured to between abut or away with respect to the plate cylinder surface by a cam mechanism not shown. If the printing plate is of a type that does not require dampening water, the dampening water supply means 8 is not necessary.

Two sets of ink supply means 9 are arranged for each of the plate cylinders 1 and 2 at the first and second printing positions, and are selected for the two printing plates on each plate cylinder 1 and 2. Ink of different colors can be supplied. For example, in this embodiment, K color (black) and M color (magenta) ink supply means 8 are arranged for the first plate cylinder 1, and C for the second plate cylinder 2. Color (cyan) and Y (yellow) ink supply means 8 are arranged.

The ink supply means 9 is composed of an ink fountain means for storing ink, and an ink roller group for kneading out the ink fed from the ink fountain means. At least one of the ink rollers which is in contact with the printing plate surface is is configured <br/> so that to between abut or away with respect to the plate cylinder surface by a not shown cam mechanism.

Incidentally, some of the dampening water supply means 8 and the ink supply means 9 are constructed so that they can be retracted from the movement paths of the first and second plate cylinders 1 and 2 as they move. .

The paper feed unit 10 takes out the print papers one by one from the pile in which the unused print papers are stacked and delivers the print papers to the paper feed cylinder 6. In this embodiment, the paper feed cylinder is rotated twice. It operates to supply the printing paper once every time. The paper discharge unit 11 receives the printed print paper from the paper discharge cylinder 7 and stacks the print paper.

Next, the plate making mechanism of this multicolor printing apparatus will be described. In this multicolor printing apparatus, the first and second plate cylinders 1 and 2 are alternately moved to the image recording position when performing the plate making operation. At this image recording position, a friction roller is brought into contact with the plate cylinder and is rotationally driven. This will be described later with reference to FIG.

The printing plate supply unit 12 is a cassette roll in which a roll-shaped unexposed printing plate is shielded from light and stored, a conveying roller and a conveying guide for conveying the drawn printing plate to the plate cylinders 1 and 2, and the printing plate. And a cutting means for cutting the sheet into a sheet. In this embodiment, a silver salt sensitive material for exposing and recording an image with a laser beam is used as a printing plate, but a thermal type printing plate that is melted or ablated by a laser may be used, for example.

The printing plate supply operation procedure is as follows. First, the front end of the printing plate pulled out from the cassette roll is clamped by the holding means (not shown) of the plate cylinders 1 and 2, and the plate cylinders 1 and 2 are rotated in this state. Then, the printing plate is wound around the plate cylinders 1 and 2,
After that, the printing plate is cut into a predetermined length and the trailing edge of the printing plate is sandwiched by the other gripping means.

The image recording unit 13 is for turning on / off the laser light.
By f, the printing plate is exposed to light to record an image. The image recording unit 13 will be described later with reference to FIG.

The developing section 14 develops the printing plate exposed by the image recording section 13. In this embodiment, the developing unit 14 is configured to scoop up the processing liquid stored in a processing tank (not shown) with a coating roller and apply the developing solution to a printing plate to perform a developing process. And an elevating means (not shown) that moves to a position close to the plate cylinder. Note that the developing unit 14 may be omitted if an image recording method that does not require development processing is adopted.

In this multicolor printing apparatus, the first and second plate cylinders 1 and 2 are moved to the image recording position, the printing plate is supplied, and the image is recorded and developed to perform the plate making operation.
When the plate making work is completed, the first and second plate cylinders 1 and 2 can be arranged at the first and second printing positions, respectively, and the printing work can be performed.

On the other hand, this multicolor printing apparatus can automatically eject the printing plate after the printing operation is completed. In this embodiment, the printing plate discharge unit 15 includes a peeling unit that peels the printing plate from the plate cylinder at the image recording position, a conveying unit that conveys the peeled printing plate, and a used used printing plate that has been conveyed. And a discharge cassette for discharging.

Next, the structure of the image pickup section 16 will be described with reference to FIG. Note that FIG. 3 is a schematic side view of the image pickup unit 16 and the paper discharge unit 11. First of all, the paper discharge section 11 is provided with the paper discharge cylinder 7
And two endless chains 30 wound between the paper discharge cylinder 7 and two pairs of gears 7'having substantially the same diameter, and the two paper chains convey the printing paper S. It comprises a plurality of gripping means 31 for carrying out, and a discharge tray 32 for stacking the printing paper S conveyed by these gripping means 31.

Gears (not shown) for engaging with the chain 30 are provided at both ends of the paper discharge cylinder 7, and two gears 7'having substantially the same diameter are arranged facing the gears. Has been done. An endless chain 30 is wound around the gear portion of the discharge cylinder 7 and the gear 7 '. The length of the chain 30 is set to an integral multiple of the circumference of the paper discharge cylinder 7.

The gripping means 31 has an openable / closable claw member for holding the front end of the printing paper S, and a plurality of gripping means 3 are provided.
1 is fixed across the two chains. The distance between the gripping means 31 corresponds to the circumferential length of the paper discharge cylinder 7. The gripping means 31 travels in a loop in synchronization with the rotation of the paper discharge cylinder 7. On the other hand, each gripping means 31 is configured to open and close in synchronization with a gripping means (not shown) provided on the paper discharge cylinder 7 by a cam mechanism (not shown), and the printing paper S is discharged from the paper discharge cylinder 7. receive. Further, the gripping means 31 is opened and closed by a cam mechanism (not shown) on the paper discharge table 32 to discharge the print paper S.

The paper discharge table 32 is a pallet-like member on which a plurality of printing papers S can be stacked, and is moved up and down by an elevating means (not shown). That is, as the print paper S is discharged, the paper discharge tray 32 is sequentially lowered to make the discharge height of the print paper S constant, and the discharge operation of the print paper S can be smoothly performed.

In the paper discharge section 11, the front end of the print sheet S is conveyed by being held by the gripping means 31, so that the rear end of the print sheet S is not fixed. For this reason, the printing paper S flaps as it is conveyed. In the present embodiment, in order to suppress the fluttering of the printing paper S, a suction roller 33 is provided on the front side of the paper discharge table 32 to stabilize the conveyance state of the printing paper S.

The suction roller 33 has a large number of fine suction holes on its surface and is connected to a vacuum pump (not shown). Further, the suction roller 33 is arranged such that its roller axis is parallel to the gripping means 31 and the top of the roller is positioned at substantially the same height as the downward passage position of the chain 30. The suction roller 33 is configured to be rotationally driven in accordance with the passing speed of the gripping means 31 or only to be rotatable. Therefore, the printing paper S
When the paper is passed over the suction roller 33, it is conveyed while being sucked onto the surface of the suction roller 33, so that the printing paper S does not flap right above the suction roller 33. Instead of the suction roller 33, a plate-shaped suction member that flatly sucks the printing paper S may be used.

The image pickup section 16 comprises an illuminating means 34 for illuminating the conveyed printing paper and an image pickup means 35 for picking up an image on the illuminated printing paper to obtain image data. The illuminating means 34 is arranged along the suction roller 33, is composed of a plurality of linear light sources that illuminate the printing paper on the suction roller 33, and is provided between the chains 30. An imaging slit is formed in the center of the light source.

The image pickup means 35 comprises a housing 36 for shielding light and dust, a mirror 37, a lens 38, and a CCD line sensor 39 arranged inside the housing. The image pickup means 35 picks up the image of the printing paper on the suction roller 33 through the slit of the illumination means 34, and the incident light of the image folded by the mirror 37 passes through the lens 38 and the CCD line sensor. The light is received at 39.
The CCD line sensor reads an image corresponding to the three colors of RGB. In this embodiment, the image on the printing paper is sequentially read line by line as the printing paper moves. In this embodiment, the entire image on the printing paper is read line-sequentially. Then, the read image data is subjected to image processing by the control unit 17.

Next, the control unit 17 shown in FIG. 2 will be described. As shown in the block diagram of FIG. 2, the multicolor printing apparatus is provided with a control unit 17 for controlling each unit of the multicolor printing apparatus including the image recording unit 13, the image pickup unit 16, and the like. The control unit 17 is composed of a computer system including an input unit 41 such as a keyboard operable by an operator, a display unit 42 such as a monitor, and a storage unit 43 capable of storing image data, various data, programs, etc. LA to receive the correct image data
It is connected to an external image data creation device (not shown) by N or the like.

The control section 17 controls each section of the multicolor printing apparatus and performs image processing of the image data picked up by the image pickup section 16. By this image processing, the coordinate positions of the positioning marks R1 to R4 are calculated, and the color density of each part of the image is measured. The former coordinate positions of the positioning marks R1 to R4 are used for setting the magnification during image recording according to the present invention. The latter color density is used for adjusting the amount of ink.

Next, the structure of the image recording section 13 will be described with reference to FIG. 4 is a block diagram of the image recording unit 13 and its peripheral portion. In the figure, first, a friction roller 51 is directly or indirectly abutted on the plate cylinders 1 and 2 in the plate making position by a driving unit (not shown). The friction roller 51 is rotationally driven by a drive motor 53 via a motor driver 52. Therefore, in this embodiment, the drive motor 53 rotates the friction roller 51,
Following this, the plate cylinders 1 and 2 can be rotationally driven. The contact between the friction roller 51 and the plate cylinders 1 and 2 is set by the roller material, contact pressure, etc. so as to prevent slippage as much as possible.

On the other hand, the image recording section 13 is a means for recording an image on the printing plates on the plate cylinders 1 and 2, and a laser light source 54 for irradiating a laser beam for recording and a laser light source 54.
And a polygon mirror 55 that deflects the laser beam emitted from the plate toward the printing plate. The laser light source 54
Is equipped with a semiconductor laser element and its peripheral optical system, and enables spot exposure by a laser beam by driving the semiconductor laser on / off. The polygon mirror 55 has five mirror surfaces for deflecting the laser beam, and is rotatably supported so as to scan the laser beam along the axial direction of the plate cylinders 1 and 2. It should be noted that the polygon mirror 55 uses the motor driver 56 to drive the drive motor 5.
It is driven to rotate by 7.

Further, the image recording section 13 includes the drive motor 5
A scanning control circuit 58 for controlling driving of the lasers 3 and 57 and an exposure control circuit 59 for controlling the laser light source 54 based on image data are provided.

The scanning control circuit 58 has two sensors 60a, 60 for detecting the origin position in the rotation of the plate cylinders 1, 2.
b and the oscillator 61, and the origin position detection signals za and zb and the reference clock signal cs are input from each. The sensors 60a and 60b are optical sensors that optically detect a detection member (not shown) installed on the plate cylinders 1 and 2, and two sensors 60a and 60b are provided to detect the origin positions with respect to the two printing areas on the plate cylinders. It is provided.

In the scanning control circuit 58, the drive motor 53 is controlled to rotate at a predetermined speed via the motor driver 52 based on the input signals. That is, the input timing intervals of the origin position detection signals za and zb are counted by the reference clock signal cs, and the drive motor 53 is feedback-controlled so that the count number becomes a predetermined value, whereby the rotational speeds of the plate cylinders 1 and 2 are controlled. It can be controlled to a desired value. Further, the scanning control circuit 58 controls the drive motor 57 via the motor driver 56 so as to rotate the polygon mirror 55 at a predetermined speed.

On the other hand, in the image recording unit 13, a position advanced in the sub-scanning direction by a predetermined offset amount from the origin position detected by the sensors 60a and 60b is set as the image recording start position in the sub-scanning direction. By changing the offset amount, the positional deviation of the image in the sub-scanning direction is corrected. Therefore, the scan control circuit 58 is
An image recording start signal ys indicating the image recording start position is generated based on the set offset amount and is given to the exposure control circuit 59.

Similarly, the image recording unit 13 sets the time point when a predetermined number of reference clock signals are counted from the origin position as the rotation end position, and outputs the plate cylinder rotation stop signal ye indicating the rotation end position.

The exposure control circuit 59 uses the reference clock signal c
Based on s, a dot clock signal dc that determines the timing of recording an image is internally generated. Then, starting from the input of the image recording start signal ys, the laser light source 54 is driven based on the image data at the timing of the dot clock signal dc to generate a laser beam for image recording. This laser beam is a polygon mirror 55
Scanning is performed in the axial direction (main scanning direction) of the plate cylinder. In addition, a start sensor 6 for detecting the laser beam in order to detect the head position of each laser beam in the main scanning direction.
Two are provided.

The exposure control circuit 59 can correct the image recording start position in the main scanning direction in the same manner as the correction of the image recording start position in the sub scanning direction. Figure 5
FIG. 9 is a diagram for explaining an image recording start position in the main scanning direction in the exposure control circuit 59. In the exposure control circuit 59, a timing memory 63 is prepared corresponding to the position (address) in the main scanning direction where the polygon mirror 55 scans. Each address position of the timing memory 63 corresponds to the position of a dot printed in the main scanning direction.

In this mechanism, first, from the time when the exposure control circuit 59 detects the laser beam by the start sensor 62, the start of the timing memory 63 (address ST in FIG. 5) based on the timing of the dot clock signal dc. Starts reading from.

When the content of the timing memory 63 becomes data indicating the start of recording (address XS in FIG. 5), the exposure control circuit 59 sequentially sends the image data to be recorded to the laser light source 54 and starts recording. When the content of the timing memory 63 becomes data indicating the end of recording (address XE in FIG. 5), the exposure control circuit 59 ends recording.

In this mechanism, the area corresponding to the addresses XS to XE becomes the recording area in the main scanning direction of the image. Therefore, when positioning the image in the main scanning direction,
The addresses XS and XE for writing the recording start and end data in the timing memory 63 may be changed.

In the above embodiment, the data is written in the timing memory 63 only at the image recording start position and the image recording end position. However, depending on the type of printing plate,
In some cases, it is necessary to set a burn-out area in the peripheral portion of the printing plate. For example, in the case of a positive type silver salt photosensitive material, a so-called "burn-off" process is required in which the peripheral portion of the printing plate is exposed to prevent ink from adhering. When performing such burn-off processing, burn-out start and burn-out end data are written in the timing memory 63. In the burn-out area thus set, the exposure control circuit 59 may record with the image data for burn-out prepared in advance.

Further, instead of the image data for burning out, various management data and marks, for example, image data such as a color management chart, may be prepared and recorded at the edge of the printing plate.

Next, a correction procedure based on the measured amount of positional deviation will be described with reference to the flowcharts of FIGS. First, the flowchart of FIG. 6 is a flowchart showing the main flow of the printing operation by the multicolor printing apparatus according to the present embodiment. In the figure, in step S1, a plate making operation is first performed to create a printing plate. In the next step S2, printing is performed with the printing plate that was made. In the next step S3, the image pickup unit 16 reads the positioning marks R1 to R4 on the printed printing paper, and the control unit 17
Calculates the amount of positional deviation. In step S4, the magnification at the time of recording the image is calculated from the obtained positional deviation amount and stored in the storage means 43. In step S5, it is determined whether or not there is the next printing work. If there is the next printing work, the process returns to step S1. If there is no next work, various end processes are performed and the present flow ends.

Next, FIG. 7 is a flow chart showing the flow for calculating the magnification from the measurement of the positional deviation amount. In the following description, FIG. 10 will be used to describe the positional deviation amount of the color plate on the printing paper. In the example shown in FIG. 10, the dotted line indicates the position of the preprinted black image k, and the upper end side of the image is the recording start side. In this example,
The image k is deformed into a trapezoidal shape (the figure is exaggerated) in which the trailing edge of the paper is widened as shown in FIG. On the other hand, the solid line is the post-printed yellow image y, showing an example in which the original square shape is maintained.
In this example, the extension of the plate cylinder in the rotation direction is ignored for easy understanding. Also, other colors are omitted.

First, in step S11, the width size k1 at the upper end and the width size k2 at the lower end of the image k are determined from the position coordinates of the positioning marks provided on the left and right of the image k.
And are calculated. Similarly, in the next step S12,
The width size y1 of the upper end of the image y and the width size y2 of the lower end are calculated.

In step S13, the magnification of the image k with respect to the image y is first obtained from the obtained width sizes k1, k2, y1 and y2. That is, the magnification h1 at the upper end of the image k with respect to the image y is h1 = k1 / y1, and the magnification h2 at the lower end is h2 = k2 / y2. Therefore, in this example, when the image y is recorded, the image y is enlarged by the magnification h1 when recording the upper end of the image and is enlarged by the magnification h2 when the lower end of the image is recorded, so that the image y has the same length as the image k. Can be

The magnifications h1 and h2 are calculated at the upper end and the lower end of the image, but not at the intermediate part. Therefore, the magnification of the intermediate portion is the above magnifications h1 and h2.
Will be obtained by interpolation calculation. For example, in the simplest linear interpolation, when the number of scanning lines in the sub-scanning direction of the image y is n, the magnification h (i) at the i-th main scanning line from the upper end is h (i). = H1
It can be represented by + i · (h2-h1) / n. (However, the value of the variable i = 0 to n)

In this embodiment, the above-obtained magnification h
With (i), the image size can be changed by changing the rotation speed of the polygon mirror in the main scanning direction (plate cylinder axis direction) in a scanning line sequential manner.

On the other hand, when the rotation speed of the polygon mirror 55 is varied as in the present embodiment, the start position in the main scanning direction designated by the timing memory 63 is displaced. Therefore, the addresses XS and XE corresponding to the recording start position and the recording end position of the timing memory 63 must be rewritten according to the speed of the polygon mirror 55.

For example, the change amount m (i, i + 1) of the image size between the i-th main scanning line and the i + 1-th main scanning line counted from the upper end of the image y is m (i, i +).
1) = y (i + 1) · h (i + 1) −y (i) · h
(I). Here, y (i) is the width size of the i-th main scanning line of the image y, and y (i) is obtained by linear interpolation calculation between the width size y1 at the upper end and the width size y2 at the lower end. = Y1 + i · (y2-y1) / n. (However, i = 0 to n)

This image size change amount m (i, i + 1)
If the image is equally distributed to the left and right of the image, it is necessary to shift the recording start position in the main scanning direction by m (i, i + 1) / 2. Normally, this m (i, i + 1) / 2 is an extremely small amount, and therefore the amount of change m in size for each main scanning line is m.
(I, +1) / 2 is line-sequentially accumulated, and when the accumulated value reaches the image size corresponding to one address of the timing memory, the address of the recording start position of the timing memory 63 corresponds to one address. It will be carried forward one by one.

In step S14, the obtained magnification h1,
h2 is stored in the storage means 43 in correspondence with the printing order or printing color of the image y, and this flow is ended.

On the other hand, the elongation of the printing paper may be larger on the paper tail side than on the paper edge side, and it may not be accurate just by linearly interpolating between the upper end portion and the lower end portion as described above. . In this case, a positioning mark may be prepared in the intermediate portion in the sub-scanning direction and the magnification may be calculated at a plurality of positions. As a result, the accuracy of interpolation between positioning marks is increased.

Next, FIG. 8 is a flow chart showing a procedure for recording while correcting the image y based on the magnification. In the figure, first, in step S21, various initial settings such as a variable i = 0 described later are made. Then, in step S22, the plate cylinder starts to rotate at a predetermined reference speed.

In the next step S23, the polygon mirror 55 is rotated at the rotation speed V = V0 / h1. Here, the rotation speed V0 is a reference rotation speed when the original image k is recorded.

In the next step S24, it is determined whether or not the recording start position in the sub-scanning direction has been reached. When the recording start position is reached, the laser light source 54 is turned on / off based on the image data in the next step S25, and the i-th main scanning is performed. (However, variable i = 0 to n)

When the recording for one main scan is completed, in the next step S26, the rotation speed V of the polygon mirror is corrected to V = V0 / h (i). However, h (i) = h
It is 1 + i * (h2-h1) / n. At this time, the recording start position in the main scanning direction by the timing memory 63 is also changed appropriately.

In the next step S27, it is determined whether i = n. That is, if i = n, it means that the recording of the image is completed, and the process proceeds to step S28. In step S28, the rotation of the plate cylinder is stopped in response to the reception of the plate cylinder rotation stop signal ye, and the operation of each unit ends.

If i = n is not satisfied in step S27, the variable i is incremented in step S29 and then step S29 is performed.
Return to 25.

As described above, in this embodiment, since the scanning speed in the main scanning direction is varied in the sub-scanning direction order, the image is magnified in the main scanning line-sequential manner.
Matches image k.

In the above embodiment, the rotation speed of the polygon mirror 55 is temporarily changed for each main scan, but the rotation speed may be changed stepwise in units of a plurality of scanning lines. . For example, in the simplest example, the rotation speed V0 / h1 of the polygon mirror 55 is in the first half area from the upper edge of the image to the center of the image, and the same rotation speed V0 is in the second half area from the center of the image to the rear edge. / H2 and the like are considered.

[Second Embodiment] In the above-described embodiment, the speed of the polygon mirror 55 is changed to perform the magnification change in the main scanning direction.
This may be achieved by changing the cycle of the dot clock signal dc for n / off control. That is, when the reference cycle of the dot clock signal dc when the image k is recorded is T0, the cycle T of the dot clock signal dc in the i-th scanning line is T = h (i) · T0,
However, h (i) = h1 + i · (h2-h1) / n (i =
0 to n). In this case as well, it is needless to say that the setting of the recording start address XS needs to be changed because the read timing of the timing memory 63 changes with the change of the dot clock signal dc.

[Third Embodiment] First and Second Embodiments
In the embodiment, only the scaling of the image in the main scanning direction (axial direction of the plate cylinder) has been described, but the printing paper also extends in the sub-scanning direction (rotating direction of the plate cylinder). Hereinafter, in this embodiment, alignment in the sub-scanning direction will be briefly described.

FIG. 11 is a diagram showing an example in which the printing paper is extended in the direction of rotation of the plate cylinder. The dotted line in the figure shows the image k of the first printing and the solid line shows the image y of the second printing. As shown in the figure, in this example, the size from the upper end of the image k to the positioning mark R5 provided in the center is k3, and the size from the body positioning mark R5 to the lower end is k4. The size from the portion to the positioning mark R5 is y3, and the size from the body positioning mark R5 to the lower end is y4. Also, the amount of positional deviation between the image k and the image y at the upper end is a.

In this case, the magnification h3 of the image k with respect to the image y is h3 = k in the first half area from the upper end to the center of the image.
3 / y3, and the magnification h4 of the image k with respect to the image y is h4 = k4 / y4 in the latter half region. Therefore, the image y
When recording, the image may be enlarged in the sub-scanning direction by the magnification h3 in the first half area and may be enlarged in the sub-scanning direction by the magnification h4 in the latter half area. Further, in aligning the image upper end portions of the image k and the image y, the recording start position of the image y may be shifted by a.

Regarding the scaling of the image in the sub-scanning direction,
The rotation speed of the plate cylinder may be changed. That is, in the first half area up to the positioning mark R5, the rotation speed U of the plate cylinder is U = U
0 / h3, in the latter half region, U = U0 / h4 may be used for rotation. However, U0 is the reference rotation speed of the plate cylinder when the image k is recorded.

[Fourth Embodiment] In the above embodiment, the image of the first printing color plate and the image of the second printing color plate are matched, but they may be reversed. For example, in the first embodiment, the image k may be previously scaled based on the image y.

[Fifth Embodiment] The magnification may be obtained corresponding to a printing color (printing order) and used when recording an image of a corresponding color. At this time, if it is stored according to the printing conditions, particularly the type of printing paper, and the magnification is changed based on the printing paper used, the positioning can be performed more accurately.

[0096]

According to the present invention, it is possible to correct the image color misregistration caused by the elongation of the printing paper and the like by scaling the image for each part.

[Brief description of drawings]

FIG. 1 is a schematic side view showing an example of a multicolor printing apparatus according to the present invention.

FIG. 2 is a block diagram showing a configuration of a control unit of this multicolor printing apparatus.

FIG. 3 is a schematic side view showing a configuration of an image pickup unit in this multicolor printing apparatus.

FIG. 4 is a block diagram showing a configuration of an image recording unit in this multicolor printing apparatus.

FIG. 5 is an explanatory diagram for explaining positioning of an image in a main scanning direction.

FIG. 6 is a flowchart showing a procedure of overall work in this multicolor printing apparatus.

FIG. 7 is a flowchart showing a procedure of magnification calculation in this multicolor printing apparatus.

FIG. 8 is a flowchart showing a procedure of image recording in this multicolor printing apparatus.

FIG. 9 is an explanatory diagram showing a printing plate.

FIG. 10 is an explanatory diagram for explaining a positional deviation of an image on a printing sheet in a plate cylinder axis direction.

FIG. 11 is an explanatory diagram for explaining a positional deviation of an image on a printing paper in a plate cylinder rotation direction.

FIG. 12 is an explanatory diagram for explaining the arrangement of images in a conventional printing apparatus.

[Explanation of symbols]

1 First plate cylinder 2 Second plate cylinder 3 first blanket body 4 Second blanket body 5 impression cylinder 6 paper feed cylinder 7 Paper ejection cylinder 9 Ink supply means 11 Paper output section 13 Image recording section 16 Imaging unit 17 Control unit 41 Input means 42 display means 43 storage means 51 friction roller 53 Drive motor (for plate cylinder rotation) 54 laser light source 55 polygon mirror 57 Drive motor (for polygon mirror) 58 Scan control circuit 59 Exposure control circuit 60a, 60b Origin position detection sensor 62 Start sensor 63 Timing memory cs reference clock signal dc dot clock signal h1 to h4 magnification R1 to R5 positioning marks T dot clock signal cycle Rotation speed of U plate cylinder V polygon mirror rotation speed

Front page continuation (72) Inventor Yoshihiro Katsuma 4-chome Tenjin Kita-cho 1-chome, Horikawa-dori Teranouchi, Kamigyo-ku, Kyoto Dai Nippon Screen Mfg. Co., Ltd. (56) Reference JP 2000-79674 (JP , A) JP-A-2-230268 (JP, A) JP-A-63-5366 (JP, A) Actual development 61-104460 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB) (Name) B41F 7/02 B41C 1/055 G03B 27/73

Claims (11)

(57) [Claims] 1. A multicolor printing apparatus for performing multicolor printing, wherein on / off control is performed at predetermined timing according to predetermined image data while rotating a plate cylinder holding a printing plate.
A laser beam emitted from a predetermined light source.
Recording an image on the printing plate by scanning over the plate
Image recording means and a plurality of printing plates on which images are recorded by the image recording means
Ink supply that supplies different colors of ink to each other
Means and ink images on the plurality of printing plates for one printing paper
Printing means for obtaining printed matter by transferring each
And printed images of different colors formed on the printed matter.
And the rotation direction of the plate cylinder in the printed image.
The first upper end and the first lower end in the first direction
The axis of the plate cylinder measured as at least the measurement point
Based on the size of the printed image in a second direction corresponding to the direction
And the image recording means is provided in front of each of the plurality of printing plates.
When the image is recorded, the scaling factor of at least the
A calculator for calculating the second upper end and the second lower end
A step and a storage unit for storing the calculated scaling ratio , the image recording unit based on the calculated scaling ratio.
Note that the size of the image is temporary or stepwise along the rotation direction.
A multicolor printing apparatus , wherein the image is magnified and recorded so as to be different stepwise . 2. The image recording means according to the scaling factor.
By changing the scanning speed of the laser beam Te,
The multicolor printing apparatus according to claim 1, wherein the image is scaled and recorded . 3. The image recording means according to the scaling factor.
Change the on / off timing of the laser beam
The multicolor printing apparatus according to claim 1 , wherein the image is magnified and recorded by performing printing. 4. The variable magnification is the second upper end and the second
2 and the lower end of the
The scaling factor between the second upper end and the second lower end is
The calculated second upper end and the second lower end.
It is determined by the interpolation calculation based on the scaling factor
That, claims 1, wherein the multicolor printing apparatus according to any one of 3. 5. The image recording section includes a first upper end portion and a front portion.
A first positioning mark indicating the first lower end is provided.
A printing plate image is further recorded on the printing plate together with the image.
And the size of the printed image in the second direction is the first upper edge.
Part and the first positioning mark at the first lower end
The multicolor printing apparatus according to claim 4, wherein the multicolor printing apparatus is measured as a distance between adjacent marks. 6. The image recording unit is arranged in front of the printed image.
Second positioning indicating the intermediate portion in the first direction
A plate image giving a mark is printed on the printing plate together with the image.
And recorded on each of the first and second print images of different colors.
Between the first upper end and the middle part in the direction of 1.
The upper space, which is a space, and the space between the lower end and the middle part.
A plurality of image recording means based on the lower spacing.
When printing the image on each of the printing plates
Is the ratio of the upper spacing between different colors
A method to calculate the lower magnification, which is the ratio of the lower spacing.
A step, and the image recording means is arranged in the rotation direction based on the upper and lower magnifications.
Record the image on the printing plate while correcting the dimensions of the image
The multicolor printing apparatus according to any one of claims 1 to 5, wherein 7. The image recording unit is configured to rotate the plate cylinder based on the upper and lower magnifications.
By changing the
The multicolor printing apparatus according to claim 6, wherein correction is performed . 8. The upper and lower magnifications correspond to a printing order.
8. The calculation according to claim 1, wherein
Multicolor printing apparatus according to Zureka. 9. A method for recording an image on a printing plate in a multi-color printing apparatus , wherein on / off control is performed at predetermined timing according to predetermined image data while rotating a plate cylinder holding the printing plate.
A laser beam emitted from a predetermined light source.
Recording an image on the printing plate by scanning over the plate
Image recording step and a plurality of prints in which images are recorded in the image recording step
Ink supply that supplies different colors of ink to the plate
Feeding process and ink images on the multiple printing plates for one printing paper
Printing process to obtain printed matter by transferring each
And printed images of different colors formed on the printed matter.
And the rotation direction of the plate cylinder in the printed image.
At least the first upper end in the first direction and the first
The axis of the plate cylinder measured with the lower end as the measurement point
Based on the size of the printed image in a second direction corresponding to the direction
In the image recording step, a plurality of printing plates are used.
When changing the zoom ratio when recording the image,
The second upper end and the second lower end of the image are calculated.
That includes a calculation step, a storage step of storing the computed the zooming magnification, and in the image recording step, on the basis of the calculated the zooming magnification, prior to said axial direction
Note that the size of the image is temporary or stepwise along the rotation direction.
An image recording method , characterized in that the image is magnified and recorded so as to be different stepwise . 10. The variable magnification in the image recording step.
The scanning speed of the laser beam can be changed according to the magnification.
The image recording method according to claim 9 , wherein the image is magnified and recorded by . 11. The variable magnification in the image recording step.
On / off timing of the laser beam according to magnification
The image is scaled and recorded by changing the
That, images recording method according to claim 10, characterized in that.