JP2007160538A - Printing equipment and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide printing equipment which attains precise printing by accurately controlling the peripheral speed of a blanket cylinder. <P>SOLUTION: The equipment has a plate cylinder 1 which comprises a plate corresponding to a printing pattern, the blanket cylinder 21 whereon a blanket 22 is wound and which receives the printing pattern from the plate and transfers it onto a glass substrate 30, a scale 24 for obtaining the peripheral speed of the blanket 22, a CCD camera 25 reading the scale 24, and a control part 10 which controls a motor 26 driving the blanket cylinder 21, based on an output from the CCD camera 25. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printing apparatus and a printing method capable of realizing high-precision printing.

  As one method for forming a flat panel display pattern such as a liquid crystal display (LCD), plasma display (PDP), EL (Electro Luminescence) display on a flat glass substrate or ceramic substrate, a cylindrical plate cylinder and this plate A printing method using a blanket cylinder (offset cylinder) arranged to face the cylinder has been proposed.

On the other hand, in recent years, glass substrates used for liquid crystal displays and the like tend to be enlarged. Nevertheless, high printing accuracy such as printing accuracy of several μm is required for a glass substrate having a size of 1 m × 1 m, for example. This means that if a cylindrical plate cylinder and a blanket cylinder having a diameter of 1 m are used, an error of the order of μm in diameter is allowed.
It is extremely difficult and costly to produce a plate cylinder and a blanket cylinder having a diameter of 1 m that can fit in an error of several μm.

  Patent Document 1 proposes a technique of providing a proximity switch for reading a base point of a plate cylinder together with a rotary encoder that obtains a rotation phase of the plate cylinder so as to accurately grasp the rotation phase of the plate cylinder.

Utility Model Registration No. 2592605

  However, no matter how accurately the rotational phase is controlled, if the cross section of the plate cylinder or blanket cylinder is not a perfect circle but an ellipse or an ellipse, the outer peripheral surface of each cylinder from the center of rotation. Since the distance (radius) varies depending on the rotation angle, the movement amount (peripheral speed) per unit time in the circumferential direction on the outer peripheral surface is different. Specifically, the peripheral speed increases at an angle where the radius of the plate cylinder or the blanket cylinder is large, and the peripheral speed decreases at an angle where the radius is small. Such a problem also occurs when the rotation center of the plate cylinder or the blanket cylinder is deviated from the true center. If the peripheral speed on the outer peripheral surface of the plate cylinder or the blanket cylinder varies depending on the angle, the printed image is also elongated or contracted accordingly.

  The present applicant has proposed various inventions in Japanese Patent Application No. 2005-056399 (unpublished at the time of filing the application) in order to solve the above-described problems with the plate cylinder.

  However, even if the rotation of the plate cylinder can be precisely controlled, if an error remains in the rotation control (peripheral speed control) of the blanket cylinder, the final printed image will be adversely affected. Particularly, a blanket made of rubber for receiving a pattern is wound around the blanket cylinder, and it is necessary to obtain a peripheral speed on the outer peripheral surface of the blanket.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a printing apparatus and a printing method that realize precise printing by accurately controlling the peripheral speed of a blanket cylinder.

In order to solve the above problems, the printing apparatus and printing method of the present invention employ the following means.
That is, the printing apparatus according to the present invention includes a plate cylinder provided with a plate corresponding to a printed pattern, and a blanket wound thereon, and also receives the pattern from the plate on the plate cylinder, and transfers the pattern to a substrate. A blanket cylinder that transfers the blanket cylinder, a blanket cylinder driving unit that rotationally drives the blanket cylinder, a scale for obtaining the peripheral speed of the blanket, a scale reading unit that reads the scale, and an output from the scale reading unit And a control unit for controlling the blanket cylinder driving unit.

  Since the scale for obtaining the peripheral speed of the blanket is read by the scale reading means, and the blanket cylinder drive unit is controlled based on the output of the scale reading means, printing that accurately reflects the peripheral speed of the blanket is realized. The Thereby, precise printing is realized.

  Furthermore, in the printing apparatus of the present invention, the scale is formed in a rotation direction of the blanket wound around the blanket cylinder.

  Since the scale is formed in the rotation direction of the blanket (printing direction, vertical direction), the peripheral speed of the blanket can be obtained when the blanket cylinder is rotated.

Furthermore, in the printing apparatus of the present invention, the scale is transferred to the blanket from the plate provided on the plate cylinder.

  Since the scale transferred from the plate is used, the work of forming the scale on the blanket outside the machine can be omitted separately.

  Furthermore, in the printing apparatus of the present invention, the scale is a belt-like belt having the same material and thickness as the blanket, and is provided on the side of the blanket.

  Since the belt-like belt having the same material and thickness as the blanket is used as the scale, the outer diameter equivalent to that of the blanket wound around the blanket cylinder can be simulated.

  Furthermore, in the printing apparatus of the present invention, the scale is formed on the blanket cylinder and on the side of the blanket.

  If the blanket thickness can be obtained accurately and the error due to the blanket thickness is expected to be small, the scale may be formed directly on the blanket cylinder.

  Furthermore, in the printing apparatus of the present invention, two or more scales are formed in the axial direction of the blanket cylinder.

  Since two or more scales are formed in the axial direction of the blanket cylinder, even when the diameter of the blanket cylinder is different at each position in the axial direction of the blanket cylinder, by using a plurality of scales (for example, each By averaging the scale readings), the blanket cylinder diameter error can be minimized.

  Further, in the printing apparatus according to the present invention, the control unit previously corrects a change in the blanket equivalent radius with respect to the peripheral speed of the blanket cylinder and / or a change in the blanket equivalent radius with respect to the blanket nip width. The blanket cylinder driving unit is controlled based on the correction map.

The equivalent radius of the blanket wound around the blanket cylinder decreases as the peripheral speed increases. Further, the equivalent radius of the blanket wound around the blanket cylinder increases as the nip width increases. Such data is obtained as a correction map in advance, and the blanket cylinder driving unit is controlled based on the correction map. As a result, the peripheral speed at the nip position where the transfer is actually performed is reflected, and precise printing becomes possible.
Here, the equivalent radius means a local radius at the nip position after the blanket is deformed.

  Further, the printing method of the present invention comprises a plate cylinder provided with a plate corresponding to a printed pattern, and a blanket wound, accepts the pattern from the plate on the plate cylinder, and prints the pattern onto a substrate. In a printing method using a printing apparatus comprising a blanket cylinder to be transferred and a blanket cylinder driving unit that rotationally drives the blanket cylinder, a scale for obtaining a peripheral speed of the blanket is read, and the blanket is based on the read result The drum driving unit is controlled.

  Since the scale for obtaining the peripheral speed of the blanket is read and the blanket cylinder driving unit is controlled based on the read result, printing that accurately reflects the peripheral speed of the blanket is realized. Thereby, precise printing is realized.

  Since the peripheral speed of the blanket wound around the blanket cylinder is obtained and controlled, the blanket can be rotationally driven at the designed peripheral speed, and precise printing can be performed.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 shows a printing apparatus according to an embodiment of the present invention.
The printing apparatus according to the present embodiment is a gravure offset printing method. The printing apparatus includes a cylindrical plate cylinder 1 that is rotationally driven at a fixed position, a cylindrical blanket cylinder 21 that is rotationally driven at a fixed position, and a flat plate 31 that travels below the blanket cylinder 21. And.

The plate cylinder 1 is a metal cylinder having a diameter of, for example, 1 m. The plate cylinder 1 includes a copper layer plated on a release layer such as Ag, and the surface thereof is polished. Photoresist is applied to the plate cylinder 1 and exposed by a laser (not shown) of a plate making apparatus provided separately. Thereafter, the photoresist is removed by development, and if necessary, hard chrome plating is applied to impart corrosion resistance. As a result, a printing pattern (plate) 5 corresponding to the printing pattern is formed on the outer peripheral surface of the plate cylinder 1.
The plate cylinder 1 may be substantially cylindrical and does not have to be a circular shape with a closed cross section. That is, the image line portion on which the print pattern 5 is formed only needs to be a cylindrical surface.

  The plate cylinder 1 is rotationally driven around a central axis L1 by a motor 16. A reduction gear 14 is interposed between the motor 16 and the plate cylinder 1. The motor 16 is provided with a rotary encoder 17 so that the angle, rotation speed, etc. of the motor 16 can be obtained. The output of the rotary encoder 17 is sent to the control unit 10.

A scale 9 is formed on the side of the print pattern 5. As described in Japanese Patent Application No. 2005-056399 by the present applicant, the scale 9 is formed at the time of laser writing of the printing pattern 5 by the plate making apparatus.
A CCD camera 11 for reading the scale 9 is provided at a position facing the scale 9. The output of the CCD camera 11 is sent to the control unit 10.

The blanket cylinder 21 is a metal cylinder having a diameter of, for example, 1 m. A rubber blanket 22 is wound around the outer periphery of the blanket cylinder 21. The ink of the printing pattern 5 on the plate cylinder 1 is received on the outer surface of the blanket 22 and then transferred to the glass substrate 30 on the surface plate 31.
A scale 24 is provided on the side of the blanket 22 in the rotational direction of the blanket cylinder 21. The scale 24 is provided at a position out of the receiving area where the printing pattern 5 is received from the plate cylinder 1. The scale 25 is formed with a large number of line segments with known intervals between the line segments. For example, a linear encoder linear scale available from Renishaw Corporation or HEIDENHAIN Corporation can be used. Specifically, a linear scale is attached to the side of the blanket 22 before or after the blanket 22 is attached to the blanket cylinder 21, and this is used as the scale 24.

  In addition, the blanket cylinder 1 should just be a substantially cylindrical shape, and the cross section does not need to be a closed circle. That is, it is only necessary that the image line portion on which the print pattern 5 is formed has a cylindrical surface, for example, a gap in which a position serving as a blanket holding mechanism that holds and fixes both ends of the blanket 22 in the vertical direction is partially cut out. The shape which has a part may be sufficient.

The blanket cylinder 21 is disposed so as to face the central axis L3 of the blanket cylinder 1 parallel to the central axis L1 of the plate cylinder 1, and the plate cylinder 1 and the blanket 22 are in contact with each other during printing. The blanket cylinder 21 is driven by a motor (blanket cylinder drive unit) 26, and a reduction gear 23 is provided between them. The motor 26 is provided with a rotary encoder 27 so that the angle, rotation speed, etc. of the motor 26 can be obtained. The output of the rotary encoder 27 is sent to the control unit 10.
A CCD camera (scale reading means) 25 for reading the scale 24 is provided at a position facing the scale 24. The output of the CCD camera 25 is sent to the control unit 10.

The surface plate 31 is disposed so as to travel below the plate cylinder 1 and the blanket cylinder 21. A glass substrate 30 is placed on the surface plate 31. The surface plate 31 translates with respect to the plate cylinder 1 and the blanket cylinder 21 (see arrow A). For example, a ball screw 33 is adopted as this drive mechanism, and the ball screw 33 is driven by a motor 36 via a reduction gear 34. The motor 36 is provided with a rotary encoder 37 so that the angle, rotation speed, etc. of the motor 36 can be obtained. The output of the rotary encoder 37 is sent to the control unit 10.
FIG. 1 shows a state after the glass substrate 30 passes under the blanket cylinder 21 and the printing pattern 35 is printed.

  The control unit 10 controls the entire printing apparatus, and performs drive control of the plate cylinder 1, the offset cylinder 21, the surface plate 31, and the like, for example. The control unit 10 includes a calculation unit 10 a that controls the rotation of the plate cylinder 1 and a calculation unit 10 b that controls the rotation of the blanket cylinder 21. Command values for various controls are output from these arithmetic units 10a and 10b.

A method of using the printing apparatus having the above configuration will be described below.
Ink is applied on the printing pattern 5 on the plate cylinder 1 by an ink application device (not shown). Then, the plate cylinder 1 is rotated based on a command from the control unit 10, and the printing pattern 5 is transferred to the blanket 22 on the blanket cylinder 21. The blanket cylinder 21 is also rotated based on a command from the control unit 10.
At the same time, the surface plate 31 translates based on the command from the control unit 10, and the print pattern received on the blanket 22 is transferred to the glass substrate 30. In this way, the print pattern 35 is formed on the glass substrate 30.

Next, control of the blanket cylinder 21 will be described with reference to FIG.
First, the blanket cylinder 21 is installed in the printing apparatus (S1). At this time, the scale 24 is attached to the blanket 22. At this time, the blanket cylinder 21 and the plate cylinder 1 are separated from each other. In this state, the motor 26 is driven to rotate the blanket cylinder 21 (S2).
During the rotation, the scale 24 is read by the CCD camera 25 (S3). Since the scale 9 is formed by repeating a number of short line segments in the rotation direction at known intervals, the read detection signal of the scale 9 is a pulse signal. The number of pulses in the minute interval Δt of the pulse signal is sent to the control unit 10 as the number of detected pulses, and compared with the number of command pulses output from the calculation unit 10b (S4). The number of command pulses corresponds to the peripheral speed of the blanket cylinder 21 defined in the design, and is the number of pulses in a minute time Δt.
The difference between the number of detected pulses and the number of command pulses is a correction amount, and after adding a predetermined gain K, an output command value is output to the motor 26 (S5, S6). This output command value is associated with the angle θ of the blanket cylinder 21 obtained from the rotary encoder 27 and stored as a correction map in a storage unit (not shown) of the control unit 10 (S7).

FIG. 3 shows the concept of comparison calculation between the number of command pulses and the number of detected pulses performed by the control unit 10.
As shown in the figure, for example, the number of command pulses at a minute interval Δt corresponding to a reference peripheral speed (desired peripheral speed given at the time of printing) on the outer surface of the blanket 22 on the blanket cylinder 21 is 10 And
At this time, as shown in FIG. 3, since the number of detected pulses is 9 at the first Δt, a correction value corresponding to this difference (shaded line in the figure) is output. Specifically, since the number of pulses is smaller by 1, it is determined that the blanket cylinder 21 is rotating slower than the reference peripheral speed, and an output command is issued so as to rotate the motor 26 earlier (see S5 in FIG. 2). At the next Δt, since the number of detected pulses is 8, an amount of correction value corresponding to the difference of 2 is output, and the motor 26 is further rotated. At the next Δt, since the number of detected pulses is 11, the number of pulses is one more than the reference value, which means that the blanket cylinder 21 rotates faster than the reference peripheral speed, and the motor An output command is issued so as to turn 26 later (see S6 in FIG. 4).
The above processing is repeated, and an output command value for one rotation of the blanket cylinder 21 is acquired for each angle θ of the blanket cylinder 21 to form a correction map.

  Such a correction map is similarly acquired for the plate cylinder 1 using the scale 9, the CCD camera 11, and the control unit 10.

  Printing is performed using the correction map thus obtained (S8). That is, after bringing the plate cylinder 1 and the blanket cylinder 21 into contact with each other, the control unit 10 sends an output command according to the correction map to the motors 26 and 16 to rotate the blanket cylinder 21 and the plate cylinder 1.

According to this embodiment, there exist the following effects.
Since the scale 24 for obtaining the peripheral speed on the outer surface of the blanket 22 is read by the CCD camera 25 and the motor 26 for driving the blanket cylinder 21 is controlled based on the output of the CCD camera 25, the blanket 22 Printing that accurately reflects the peripheral speed of the outer surface is realized. As a result, rotation at the reference peripheral speed becomes possible, and precise printing is realized without any deviation of the printing pattern.
Since the scale 24 formed on the outer surface of the blanket 22 is read, the peripheral speed of the blanket can be directly obtained. Therefore, even if the diameter of the blanket cylinder 21 and the thickness of the blanket 22 are different in the circumferential direction, or the central axis L3 of the blanket cylinder 21 is deviated from the true center, the peripheral speed can be accurately obtained. it can.

This embodiment can also be modified as follows.
[Real-time control]
Printing is performed immediately after the plate cylinder 1 and the blanket cylinder 21 are installed in the printing apparatus without creating a correction map before printing. In this case, the motors 16 and 26 are driven in real time by an output command value obtained by adding a correction amount based on the difference between the number of detected pulses obtained by the CCD cameras 11 and 21 and the number of command pulses.
In this way, correction is performed in real time, and it is not necessary to prepare a correction map in advance, so that the setup time can be shortened.
Further, for example, it is possible to cope with errors that occur during printing, such as thermal expansion of the plate cylinder 1 and the blanket cylinder 21.

The CCD cameras 11 and 25 have a slow detection speed and may make real-time measurement difficult. In such a case, an electromagnetic method using inductosin or an optical method using the interference scanning principle is used.
For example, an MP scale manufactured by Mitsubishi Heavy Industries, Ltd. can be used as the inductosin as an electromagnetic method. Specifically, the scales 24 and 9 formed on the blanket cylinder 21 and the plate cylinder 1 are comb-shaped coils, and a similar comb-shaped coil is disposed on the detection side facing the scale. An alternating current is passed through each coil to generate an induced voltage due to electromagnetic induction. When the positions of the scales 24 and 9 and the detection side change relatively, the induced voltage also changes, and the positions of the scales 24 and 9 are read in association with the changed voltages.
The interference scanning principle as an optical method is used as follows.
For example, step gratings in which a reflection line having a height of 0.2 μm is provided on a flat reflection surface are formed as scales 24 and 9. On the detection side facing the scales 24 and 9, a scanning plate is disposed as a transparent phase grating having the same grating interval as the scales 24 and 9.
When the light from the light source is irradiated and passed through the scanning plate, the order having approximately the same luminous intensity -1.0-. Diffracted into +1 partial waves. Most of these diffracted partial waves are diffracted by the scales 24 and 9 into orders +1 and −1. These partial waves meet again at the scanning plate, are diffracted again, and interfere with each other. This basically forms three waves that are emitted from the scanning plate at different angles. A light receiving element arranged on the detection side converts the intensity of these lights into an electric signal and reads the positions of the scales 24 and 9.

[Correction of diameter error in the axial direction]
The scale 24 shown in FIG. 1 is provided on one side of the blanket 22, but may be provided on both sides of the blanket. For example, as shown in FIG. 4, two scales 24 are provided on both sides along the vertical direction (printing direction, rotation direction) of the blanket 22. Note that the blanket 22 in FIG. 4 is in a state where it is unfolded in a planar shape before being wound around the blanket cylinder 21.
Thus, the scales 24 provided at both ends of the blanket 22 are read by the CCD cameras provided for the scales 24, respectively. That is, two CCD cameras 25 shown in FIG. 1 are provided at both ends of the blanket cylinder 21.
Thereby, for example, when the blanket cylinder 21 has a truncated cone shape, even if the angle θ is the same, the diameter is different if the position in the direction of the central axis L3 is different. In this case, if the position in the direction of the central axis L3 is different, the peripheral speed on the surface of the blanket 22 is different. In such a case, the scales 24 provided at both ends of the blanket 22 are used in order to average the diameter error in the direction of the central axis L3. That is, an average value of the number of detection pulses obtained by each CCD camera 25 is obtained, and control is performed based on this average value.

[Modification of scale]
As shown in FIGS. 5 and 6, the shape of the scale provided in the blanket 22 can be changed. That is, instead of using the scale 24 in which many short line segments are arranged in the vertical direction, a scale in which the cross marks 40 are arranged in the vertical direction is used. As shown in FIG. 6, the cross mark 40 is composed of a horizontal line segment 40a extending in the width direction of the blanket 22 and a vertical line segment 40b orthogonal to the horizontal line segment 40a and extending in the vertical direction. In this way, since the center position 40c where the horizontal line segment 40a and the vertical line segment 40b intersect is detected by using the cross shape, the vertical position of the cross mark 40 constituting the scale 24 and the width direction perpendicular thereto. The position can be accurately grasped. Thereby, the reading accuracy of the scale 24 is improved and the printing accuracy is improved.

Moreover, as shown in FIG. 7, it is good also as forming a scale in the blanket 22 by printing.
The scale 24 shown in FIG. 1 is configured by attaching a linear scale, for example. However, as shown in FIG. 7, a scale 43 transferred from a scale pattern 42 formed on the plate cylinder 1 is used. It may be used. In this way, the trouble of sticking the linear scale on the blanket 22 can be saved, and workability is improved.
However, the scale pattern 42 formed on the plate cylinder 1 needs to be formed by line segments having an accurate interval so that the peripheral speed on the surface of the blanket 22 can be accurately measured.

Further, as shown in FIG. 8, a belt-like belt 46 may be wound around the blanket cylinder 21 around the blanket 22, and the scale 47 may be formed on the outer surface of the belt 46. A belt 46 having the same material and thickness as the blanket 22 is used. In this way, the outer diameter equivalent to that of the blanket 22 wound around the blanket cylinder 21 can be simulated, and the peripheral speed of the outer surface of the blanket 22 can be obtained in the same manner as the scale 24 shown in FIG. it can.
FIG. 8 shows a blanket holding mechanism 48 that holds and fixes both ends of the blanket 22 and the belt 46.

Further, as shown in FIG. 9, a scale 50 may be provided on the surface of the blanket cylinder 21 instead of on the blanket 22.
FIG. 9 shows a configuration in which a scale 50 is formed on the blanket cylinder 21 by a plate making apparatus that forms a plate on the outer surface of the plate cylinder 1. The scale 50 is written by the laser emitted from the laser head 3.
When the thickness of the blanket 22 can be accurately obtained and the error in the rotational direction θ due to the thickness is expected to be small, the scale is directly applied to the blanket cylinder 21 without providing a scale on the surface of the blanket 22. 50 is provided. Thus, since the plate making apparatus of the plate cylinder 1 can be used, it is not necessary to purchase a separate linear scale.

[Correction of equivalent radius of blanket]
Since the blanket 22 is made of an elastic body such as rubber, the equivalent radius changes according to the peripheral speed and the nip width. In other words, the radius of the blanket 22 which is wound blanket cylinder 21 wound, compared to the radius r ₀ in the stationary state, the local radii i.e. equivalent radius at the nip position when the peripheral speed is increased becomes smaller (FIG. 10 (a) reference). This is because when the peripheral speed increases, the contact time between the blanket 22 and the glass substrate 30 is shortened, and the contact force is reduced. Then, the deformation amount of the blanket 22 becomes smaller than before the peripheral speed increases. As a result, the apparent radius (equivalent radius) of the blanket 22 is reduced. Thus, the equivalent radius decreases as the peripheral speed increases.

In addition, the radius of the blanket 22 wound around the blanket cylinder 21 increases as the nip width increases as the nip pressure increases as compared to the radius r ₀ in a stationary state (see FIG. 10B). . The reason for this will be described with reference to FIG. In the drawing, the contact state between the blanket 22 and the glass substrate 30 is shown. The contact between the blanket 22 and the plate cylinder 1 can be considered similarly.
When the contact force between the blanket cylinder 21 and the glass substrate 30 is increased, the contact portion of the blanket 22 is deformed so as to follow the planar shape of the glass substrate 30, and the nip width increases. That is, the shape of the blanket 22, the state of deformation before the blanket 22a of radius r ₀ keeping the circular, changes the state of the deformed blanket 22b of radius r ₁ which contact portion is deformed. The contact portion of the deformed blanket 22b is deformed so as to follow the planar shape, the radius of curvature of the contact portion is increased (i.e., the radius increases from r ₀ to r _1), the apparent blanket 22 as a result The upper radius (equivalent radius) will increase. Thus, the equivalent radius increases as the nip width increases.

  The data shown in FIGS. 10A and 10B relating to the equivalent radius of the blanket 22 is stored in the storage area of the control unit 10 as a correction map, and the peripheral speed is calculated using this equivalent radius during printing. To do. For example, the plate cylinder 1 and the blanket cylinder 21 are mounted on a printing apparatus, and the nip width between the blanket cylinder 21 and the plate cylinder 1 and the nip width between the blanket cylinder 21 and the glass substrate 30 are measured. Based on the measured nip width, an equivalent radius is obtained from the correction map shown in FIG. For the peripheral speed, an equivalent radius is obtained from the correction map shown in FIG. 10A based on the desired reference peripheral speed. Using these equivalent radii, the command pulse (see FIG. 3) used during printing is corrected. In this way, the peripheral speed of the nip position where the transfer is performed is accurately reflected, so that more precise printing can be realized.

It is the perspective view which showed the principal part of the printing apparatus of this invention. It is the flowchart which showed the control method of the blanket cylinder. It is the figure which showed the relationship between the number of detection pulses and the number of command pulses. It is the top view which showed the modification which provided the scale in the both ends of the blanket. It is the top view which showed the modification of the scale. It is the top view which showed the cross mark which comprises a scale. It is the perspective view which showed the other formation method of the scale. It is the perspective view which showed the other formation method of the scale. It is the perspective view which showed the structure which forms a scale in the surface of a blanket cylinder. It is a graph used for correction | amendment of the equivalent radius of a blanket, (a) shows the change of the equivalent radius with respect to speed, (b) shows the change of the equivalent radius with respect to nip width. It is sectional drawing which showed the reason for the equivalent radius of a blanket increasing with the increase in nip width.

Explanation of symbols

1 Plate Cylinder 10 Control Unit 21 Blanket Cylinder 22 Blanket 24 Scale 26 Motor (Blanket Drive Unit)
25 CCD camera (scale reading means)

Claims (8)

A plate cylinder provided with a plate corresponding to the printed pattern;
As the blanket is wound, a blanket cylinder that receives a pattern from the plate on the plate cylinder and transfers the pattern to a substrate;
A blanket cylinder driving unit for rotating the blanket cylinder;
A scale for obtaining the peripheral speed of the blanket;
Scale reading means for reading the scale;
And a control unit that controls the blanket cylinder driving unit based on an output from the scale reading unit. The printing apparatus according to claim 1, wherein the scale is formed in a rotation direction of the blanket wound around the blanket cylinder. The printing apparatus according to claim 1, wherein the scale is transferred to the blanket from the plate provided on the plate cylinder. The printing apparatus according to claim 1, wherein the scale is a belt-like belt having the same material and thickness as the blanket, and is provided on a side of the blanket. The printing apparatus according to claim 1, wherein the scale is formed on a side of the blanket on the blanket cylinder. 6. The printing apparatus according to claim 1, wherein two or more scales are formed in an axial direction of the blanket cylinder. The control unit obtains, in advance as a correction map, a change in the equivalent radius of the blanket with respect to the peripheral speed of the blanket cylinder and / or a change in the equivalent radius of the blanket with respect to the nip width of the blanket. 8. The printing apparatus according to claim 1, wherein the blanket cylinder driving unit is controlled based on the printing apparatus. A plate cylinder provided with a plate corresponding to the printed pattern;
As the blanket is wound, a blanket cylinder that receives a pattern from the plate on the plate cylinder and transfers the pattern to a substrate;
In a printing method by a printing apparatus comprising a blanket cylinder driving unit that rotationally drives the blanket cylinder,
Read the scale to obtain the peripheral speed of the blanket,
A printing method characterized in that the blanket cylinder driving unit is controlled based on the reading result.

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