JP3537544B2 - Gravure engraving system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gravure engraving system, and more particularly to a gravure engraving system for producing an intaglio for gravure printing by engraving a plurality of cells on the surface of a gravure cylinder.

[0002]

2. Description of the Related Art In a gravure engraving system, a microscopic recess called a cell is formed on the surface of a gravure cylinder while rotating a cylindrical gravure cylinder having a copper plating on the surface thereof. This is a system for producing. The amount of ink to be filled in the cell is controlled by the depth and width (area) of the cell, so that the print density is expressed. An engraving head is used to form cells on the surface of the gravure cylinder. The engraving head is provided with a stylus having a diamond needle (bite) at the tip, and engraving is performed by vibrating the stylus at a frequency of several KHz.

FIG. 17C shows a waveform of an engraving signal applied to an engraving head in a conventional gravure engraving system, and corresponds to a stylus displacement waveform. This signal waveform is obtained by superimposing a density signal waveform as shown in FIG. 17B on a high-frequency carry signal waveform as shown in FIG. 17A (ie, modulating the carry signal with the density signal). Things. By applying such an engraving signal to the engraving head, cells having a depth and width corresponding to the density signal can be engraved on the surface of the gravure cylinder. The dashed line R in FIG. 17C corresponds to the surface of the gravure cylinder, and the hatched portions in the figure correspond to the cells.

FIG. 18 is a diagram showing an example of a top surface shape of a cell engraved by a conventional gravure engraving system and an arrangement state thereof. As shown in FIG. 18, conventional cells are regularly arranged. The shape of each cell is approximate to a rhombus as shown in FIG.

[0005]

The level of the density signal changes according to the gradation designated on the image data, that is, the print density. The level of the density signal appears as the width of the cell (width in the sub-scanning direction). Therefore, the gradation specified on the image data corresponds to the width of the cell, and the cell area is approximately proportional to the square of the width of the cell. The area is, as shown in FIG.
It changes like a function. As described above, in the conventional gravure engraving system, since the cell area is not linearly proportional to the gradation on the image data, the density of the printed matter cannot be accurately controlled as it is. Therefore, conventionally, a test engraving was performed to observe a change in the density of an actual printed matter, and correction of image data was performed based on the observation result.

Accordingly, an object of the present invention is to provide a gravure engraving system in which the area of a cell actually engraved is linearly proportional to the gradation specified by the original image data. is there.

[0007]

Means for Solving the Problems According to claim 1 of the present invention,
A gravure engraving system for producing an intaglio for gravure printing by engraving a plurality of cells on the surface of a gravure cylinder, comprising a rotating means for rotating the gravure cylinder in a main scanning direction, and having a constant frequency and a constant amplitude. Carry signal generating means for generating a sinusoidal carry signal, density signal generating means for generating a density signal whose level changes according to the gradation of given image data, and superimposing the density signal on the carry signal, An engraving signal generating means for generating an engraving signal, a stylus for engraving a cell, and a sub stylus for engraving the stylus with respect to a gravure cylinder rotating in the main scanning direction by reciprocating vibration according to the engraving signal. Stylus feed means for feeding in the scanning direction, the area of the cell is linear with respect to the change in the gradation of the original image data As proportional, after correcting the gradation of the image data of the original, and a gradation correction means for providing a density signal generating means.

According to a second aspect of the present invention, in the first aspect of the present invention, the gradation correcting means changes the area of a cell engraved when the original image data is directly supplied to the density signal generating means for each gradation. A first calculating means for calculating, a second calculating means for calculating a cell area in a case where the area of the cell is linearly proportional to a change in gradation of the original image data for each gradation,
And third calculating means for calculating a correction value for each gradation value of the original image data based on the calculation result of the second calculating means.

[0009]

In the invention according to the first aspect, the gradation correcting means corrects the gradation of the original image data so that the cell area is linearly proportional to the change in the gradation of the original image data. After that, the signal is supplied to the density signal generating means. As a result, the area of the cell actually engraved is linearly proportional to the change in the gradation of the original image data, so that it is possible to accurately control the print density without performing test engraving. .

In the invention according to claim 2, the gradation correcting means calculates the area of a cell to be engraved for each gradation when the original image data is directly supplied to the density signal generating means, and calculates the original image data. The cell area in the case of being linearly proportional to the change in gradation is calculated for each gradation, and a correction value for each gradation value of the original image data is calculated based on the calculation result.

[0011]

1 and 2 are a front view and a plan view, respectively, of a gravure engraving machine used in a gravure engraving system according to one embodiment of the present invention. 1 and 2, the gravure engraving machine 100 includes a bed 1, a headstock 2 fixed to the upper surface of the bed 1, a tailstock 3 disposed opposite to the headstock 2, and a table 4. It has. The tailstock 3 is movable in the left-right direction of the apparatus along a pair of guide rails 6 arranged on the upper surface of the bed 1. The tailstock 3 can be moved toward or away from the headstock 2 by a drive mechanism 9 including a motor and a belt provided on the bed side. In addition, the center 12 of the tailstock 3 can be freely protruded and retracted by the cylinder 13. The table 4 is movable left and right along a pair of guide rails 7 arranged on the upper surface of the bed 1. The table 4 can be moved along the guide rails 7 by the ball screw 15 arranged between the pair of guide rails 7 and the drive motor 16 for driving the same. The spindle 10 of the headstock 2 is rotated by a drive mechanism 11 including a drive motor and a belt. In such a configuration, the gravure cylinder 14 is supported between the main shaft 10 and the center 12, as shown by a two-dot chain line in FIG.

An engraving head 21 is provided on the table 4 so as to be movable in the front-rear direction of the apparatus (a direction perpendicular to the plane of FIG. 1). A guide rail 20 is provided on the upper surface of the table 4, and the engraving head 21 is moved by a driving mechanism including a ball screw 22 and a driving motor 23.

FIG. 3 is a perspective view showing a stylus provided on the engraving head 21 and a driving mechanism thereof. In FIG. 3, a stylus 30 is fixed to a tip of a torsion shaft 31, and one end of the stylus 30 has a diamond cutting tool 32 attached thereto. The other end of the torsion shaft 31 is fixed to the fixing part 33. Further, a rotor 34 having a diamond shape in a plan view is fixed to an intermediate portion of the torsion shaft 31. A laminated magnetic body (stator) 35 is arranged around the rotor 34 so as to sandwich the rotor 34, and a permanent magnet 36 for applying a magnetic force to the stator 35 is arranged on a side of the stator 35. . Also, the rotor 34
A coil 37 is disposed between the rotor 34 and the stator 35 around the periphery of the coil 37. In such a configuration, the coil 3
By applying the engraving signal to 7, the stylus 30 vibrates in the direction of arrow B in the figure according to the frequency of the engraving signal.

FIG. 4 is an external view of the diamond cutting tool 32. In particular, FIG. 4 (a) is a front view, FIG. 4 (b) is a left side view thereof, and FIG. It is a bottom view. As shown in FIG.
Has the shape of a triangular pyramid, and the vertex 32a of this triangular pyramid
Carves the surface of the gravure cylinder 14 with.

The gravure engraving machine of the first embodiment configured as described above carves cells along the main scanning direction (the circumferential direction of the gravure cylinder 14) shown in FIG. The engraving head 21 is fed at a predetermined pitch in the sub-scanning direction (a direction parallel to the rotation axis of the gravure cylinder 14), and engraves the next row of cells. By repeating this,
On the surface of the gravure cylinder 14, an intaglio composed of a plurality of cells is formed.

FIG. 6 is a block diagram showing an electrical configuration of a gravure engraving system using the gravure engraving machine 100 shown in FIGS. In FIG. 6, a gravure engraving machine 100 is connected to a data creation device 201 including a personal computer or the like. The data creation device 201 includes a reading device 202 such as a scanner.
And other image systems 203, an external storage device 204 such as a hard disk device, and an operation unit 205 such as a keyboard and a mouse. Data creation device 20
1 creates gravure platemaking image data based on data read from a predetermined document by the reading device 202 and other data obtained from the image system 203. For example, the data creation device 201 obtains image data for offset from another image system, and creates image data by performing offset / gravure conversion. The operator operates the operation unit 205 to input various data or instructions (for example, engraving conditions such as the number of lines and cell patterns (eron gate, compressed, etc.)) to the data creation device 201. Based on input data or an instruction from the operation unit 205, the data creating device 201 generates carry command data, a sub-scanning command signal, and a main scanning command signal together with the image data. These data and signals are provided to the gravure engraving machine 100.

The gravure engraving machine 100 includes a density signal generating unit 101, a carry signal generating unit 102, a sub-scanning motor 103, a main scanning motor 104, an adding unit 105, an engraving head 21, a sub-scanning motor 107, , A main scanning motor 108. The density signal generator 101 generates a density signal based on image data provided from the data generator 201. Carry signal generator 102
Determines the amplitude and the offset amount based on the carry command data provided from the data creation device 201, and generates a carry signal. The adder 105 adds the density signal from the density signal generator 101 and the carry signal from the carry signal generator 102, and then applies the result to the engraving head 21 as an engraving signal. The sub-scanning motor 107 is a motor for moving the engraving head 21 in the sub-scanning direction. The main scanning motor 108 is a motor for rotating the gravure cylinder 14. Sub-scanning motor control unit 1
Numeral 03 denotes a data generating device 20 for changing the feed amount of the engraving head 21 in the sub-scanning direction according to engraving conditions such as the number of lines.
1 on the basis of the sub-scanning command signal from
7 is controlled. The main scanning motor control unit 104 controls the main scanning motor 108 based on a main scanning command signal from the data creating device 201 to change the rotation speed of the gravure cylinder 14 according to the difference in the cell pattern and the number of lines. .

In this embodiment, as shown in FIG.
Of values 0 to 256 that can be represented by 8 bits, values 29 to 22
8 is used to express the gradation. Here, the value 29 corresponds to the minimum density gradation, and the value 228 corresponds to the maximum density gradation. Therefore, between the minimum density gradation and the maximum density gradation,
It is represented by 199 gradation values.

Further, in this embodiment, when engraving a large-sized cell, a portion communicating with each other, that is, a channel C (see FIG. 8A) is formed between cells adjacent in the main scanning direction. ing. By forming such a channel C, the flow of ink in the main scanning direction is improved,
The efficiency of filling each cell with ink is improved. In order to form the channel C, as shown in FIG. 9, the level of the vertex portion K of the engraving signal corresponding to the maximum density cell is set lower than the reference level R corresponding to the surface of the gravure cylinder. As a result, the width of the cell is increased, and a channel appears between cells adjacent in the main scanning direction.

FIG. 10 is a flowchart showing the operation of the gravure engraving system according to the above embodiment. This figure 1
The operation of 0 is mainly executed by the data creation device 201 of FIG. The operation of the above embodiment will be described below with reference to FIG.

First, the data creating apparatus 201 selects and inputs parameters necessary for correction from various preset parameters (step S1). The parameters input at this time are the maximum cell width W _MAX and the minimum cell width W
And _MIN, and the maximum channel width C _{MA X,} a cell pitch P ₁ in the sub-scanning direction, a cell pitch P ₂ Doo in the main scanning direction. Here, the maximum cell width W _MAX is the maximum density gradation 228
, Ie, the width of the maximum density cell in the sub-scanning direction (see FIG. 7). The minimum cell width W _MIN is the width of the cell corresponding to the lowest density gradation 29, that is, the minimum density cell in the sub-scanning direction (see FIG. 7). The maximum channel width C _MAX is the width of the channel C in the sub-scanning direction generated when engraving the maximum density cell (the maximum width of the channel C; FIG. 8).
Reference).

Next, the data creating device 201 calculates a predetermined value required for area correction, which will be described later, based on the various parameters input in step S1 (step S2).
Hereinafter, the predetermined value will be described in detail.

1. γ_C Operation of This γ_C Is the gradation of the smallest cell when the channel C appears
Value. FIG. 8A shows the top surface shape of the maximum density cell.
are doing. In this case, the cell shape is the maximum cell width W_MAX 
And the maximum channel width C_MAX And On the other hand, FIG.
(B) is the top surface shape of the smallest cell when the channel C appears.
Shape. The cell width in this case is W _MAX -C_MAX 
It becomes. Here, generally, the cell width W (W_MAX ≧ W ≧ W
_MIN ) Is proportional to the gradation γ (228 ≧ γ ≧ 29)
Therefore, the cell width W is obtained by the following equation (1). The following equation
In (1), (W_MAX -W_MIN ) / 199 is a unit
The increment of the cell width per gradation is shown.

(Equation 1)

Here, the minimum cell width W _MAX -C _MAX when the channel C appears can be obtained by substituting γ _C (the gradation of the minimum cell when the channel C appears) into the above equation (1). It is obtained by the following equation (2).

(Equation 2)

When the above equation (2) is modified to obtain the gradation γ _C , the following equation (3) is obtained.

[Equation 3]

2. Calculation of f / e This value f / e is frequently used for calculation of area correction performed later. Therefore, by calculating the value f / e in advance, the subsequent correction calculation is simplified. Where f
Is の of the cell width W when the channel C does not appear (when γ <γ _C ), and is obtained by the following equation (4).

(Equation 4)

On the other hand, e is 1/2 of the total amplitude α of the carry signal (see FIG. 9A), and is obtained by the following equation (5).

(Equation 5)

Accordingly, f / e is obtained from the above equations (4) and (5) by the following equation (6).

(Equation 6)

3. First, the area of the cell when the channel C does not appear (when γ _C > γ ≧ 29) will be described. Now, the cell width W (=
Considering the area of the cell having 2f), the cell area A
Is four times the area of the hatched portion in FIG. In FIG. 11, the equation of the outer curve φ of the cell is expressed by the following equation (7).

(Equation 7)

The coordinates of the point x ₀ in FIG. 11 are obtained as the value of x when y = 0 is set in the above equation (7), and is expressed by the following equation (8).

(Equation 8)

Therefore, the cell area A can be obtained by the following equation (9).

(Equation 9)

Next, when channel C appears (228 ≧
(when γ ≧ γ _C ) will be described. In this case, the area A of the cell, as shown in FIG. 12, the cell to the sum of the original area (area of the hatched region) (the area of the rectangular area where dots attached) area of A ₃ and the channel unit A ₄ Become.
Here, the area A ₃ is obtained by substituting f = 2e into the above equation (9), and A ₃ = 2eP ₂ . On the other hand, the channel portion has a rectangular shape in which the length of one side is P ₂ and the length of the other side is C, and the area A ₄ is A ₄ = P ₂ C. Therefore, the entire cell area A is obtained by the following equation (10).

(Equation 10)

A cell area A having a predetermined cell width W (= 2f) is obtained from the above equations (9) and (10). Note that the gradation γ
Determines the cell width W, the cell area A becomes the gradation γ
Can be determined by

4. Calculation of the area increment ΔA per unit gradation Assuming that the maximum cell area is A _MAX and the minimum cell area is A _MIN , the area increment ΔA per unit gradation is expressed by the following equation (11).
Is required.

(Equation 11)

In the above equation (11), the maximum cell area A _MAX can be obtained by the following equation (12) by substituting W = W _MAX into the above equation (10).

(Equation 12)

The minimum cell area A _MIN can be obtained by substituting f = f _MIN into the above equation (9) to obtain the following equation (1).
Required in 3).

(Equation 13)

In the above equation (13), f _MIN / e
Is obtained by the following equation (14).

[Equation 14]

As described above, in step S2, the gradation γ _C of the minimum cell when the channel C appears, f / e,
Formula for calculating cell area A and increment Δ of area per unit gradation
A is required.

Next, the data creating device 201 creates a data conversion table for making the gradation of the original image data and the area of the cell a linear relationship (step S3). First, the data conversion table creation operation will be described with specific numerical values. In addition, each numerical value shown below is
It is pointed out in advance that this is an example, and the present invention is not limited to these numerical values.

As shown in FIG. 13, the gradation specified on the original image data (image data taken in from the reading device 202 or another image system 203) is 29 to 228.
199 stages. Without correcting the gradation on the original image data, when it is applied to the density signal generating unit 101, the area of the cell, 841 (= 29 ²⁾ to 51
It changes within the range of 984 (= 228 ² ). If the area of the cell increases or decreases by (51984-841) / 199 = 257 per unit gradation, the cell area ideally changes with respect to the gradation of the original image data, as shown in FIG. That is, it is linearly proportional. For example, if the original image data has a gradation of 100, the ideal cell area is 841 + 257 (100−29) = 19088. The gradation of the original image data with respect to this ideal area 19088 is 138 as shown in FIG.
In step S3, a table for performing such gradation conversion is created.

In step S3, the data creation device 2
01 is obtained by using the equations (9) and (10) obtained in step S2 described above, and each gradation γ = 29 of the original image data.
The cell areas A (29) to A (228) with respect to .about.228 are calculated to create a first list as shown in FIG. Next, the data creating device 201 calculates ideal cell areas A ′ (29) to A ′ (228) for each gradation γ = 29 to 228 of the original image data using the following equation (15). Then, a second list as shown in FIG. 16B is created. A ′ = ΔA (γ−29) + A _MIN (15) Next, the data creation device 201 calculates the corrected gradation value corresponding to each ideal cell area on the second list from the first list. A search is performed to create a gradation data conversion table as shown in FIG.

Next, the data creating device 201 inputs image data from the reading device 202 or another image system 203 and uses the data conversion table (see FIG. 16 (c)) created in step S3 to generate image data. The gradation value is converted (step S4). Thereby, the data creation device 2
From 01, the image data whose gradation has been corrected is output to the density signal generation unit 101. Therefore, the area of the cell is linearly proportional to the gradation on the original image data.

The density signal generation unit 101 performs the processing shown in FIG.
A density signal as shown in FIG. This density signal is supplied to carry signal generating section 102 in adder 105.
9 (see FIG. 9A) and applied to the engraving head 21 as an engraving signal (see FIG. 9C). The engraving head 21 reciprocates the stylus 30 in the direction B in FIG. 3 in accordance with the engraving signal provided. At this time, the main scanning motor 108 rotates the gravure cylinder 14 in the main scanning direction. by this,
One row of cells is engraved along the main scanning direction. Sub-scanning motor 107 moves the engraving head 21 each time the engraving of cells of one column is completed in the sub-scanning direction by a predetermined pitch P _1. By repeating such an operation, a plurality of rows of cells are engraved in the gravure cylinder 14.

In the above embodiment, the cell area for each gradation when the original image data is not corrected is obtained by calculation. However, the cell area is measured in advance by trial engraving, and the actual measurement is performed. The value may be registered in the system and used.

In the above embodiment, a data conversion table is created in advance, and when actual image data is input, the data conversion table is searched to obtain a corrected gradation. However, in the case where the data creating device 201 has a high-speed CPU, the corrected gradation is obtained only by the calculation at the time of inputting the image data without using such a data conversion table. Is also good.

Further, in the above-described embodiment, the stylus 30 is moved at a predetermined pitch in the sub-scanning direction every time the engraving of one row of cells in the main scanning direction is completed. The cells may be sent in the sub-scanning direction to engrave the cells in the gravure cylinder 14 in a spiral shape.

[0047]

According to the first aspect of the present invention, the tone of the original image data is corrected and then applied to the density signal generating means. Cell area can be linearly proportional. As a result, it is possible to accurately control the print density without performing trial engraving as in the related art.

According to the second aspect of the present invention, when the original image data is directly supplied to the density signal generating means, the area of the cell to be engraved and the change in the gradation of the original image data are linearly changed. Since the gradation of the original image data is corrected based on the calculation result with the area of the cell to be engraved in the case of proportionality, the gradation of the original image data can be easily and accurately corrected.

[Brief description of the drawings]

FIG. 1 is a front view of a gravure engraving machine used in a gravure engraving system according to one embodiment of the present invention.

FIG. 2 is a plan view of a gravure engraving machine used in the gravure engraving system according to one embodiment of the present invention.

FIG. 3 is a perspective view showing a stylus provided on the engraving head 21 of FIG. 1 and a driving mechanism thereof.

4 is an external view of the diamond cutting tool 32 of FIG.

FIG. 5 is a diagram for explaining a main scanning direction and a sub-scanning direction with respect to the gravure cylinder.

FIG. 6 is a block diagram showing an electrical configuration of a gravure engraving system using the gravure engraving machine shown in FIGS. 1 and 2.

FIG. 7 is a diagram for explaining the gradation expression of image data employed in the gravure engraving system of the embodiment.

FIG. 8 is a diagram showing a relationship between a channel generated between cells adjacent in the main scanning direction and a cell width in the present embodiment.

FIG. 9 is a waveform diagram of various signals used in the gravure engraving system of the present embodiment.

FIG. 10 is a flowchart showing the operation of the gravure engraving system of the present embodiment.

FIG. 11 is a diagram for explaining a method for obtaining a cell area when a channel C does not appear;

FIG. 12 is a diagram for explaining a method of obtaining a cell area when a channel C appears.

FIG. 13 is a diagram showing a state in which the cell area changes nonlinearly with respect to the gradation of the image data before correction.

FIG. 14 is a diagram showing a state in which the cell area changes linearly with respect to the gradation of image data after correction.

FIG. 15 is a diagram illustrating a method of obtaining a gradation of image data after correction from a relationship between a gradation of image data before correction and a cell area.

FIG. 16 is a diagram illustrating a procedure for creating a conversion table of gradation data in the present embodiment.

FIG. 17 is a waveform diagram of various signals used in a conventional gravure engraving system.

FIG. 18 is a diagram showing a top surface shape of a cell carved by a conventional gravure engraving system and an arrangement state thereof.

FIG. 19 is a diagram showing a top surface shape of a cell carved by a conventional gravure engraving system in a pseudo equivalent to another geometric figure.

FIG. 20 is a diagram showing that the gradation of the original image data and the cell area have a non-linear relationship.

[Explanation of symbols]

14 ... gravure cylinder 21 ... Engraving head 30 ... Stylus 32 ... diamond bite 100 ... gravure engraving machine 101: density signal generation unit 102: Carry signal generator 103: sub-scanning motor control unit 104: Main scanning motor control unit 105 ... Addition unit 107: Sub-scanning motor 108 ... Main scanning motor 201: Data creation device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-191001 (JP, A) JP-A-7-64276 (JP, A) JP-A-3-73343 (JP, A) 507722 (JP, A) Table 9-502936 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41C 1/045

Claims (2)

(57) [Claims] 1. A gravure engraving system for producing an intaglio for gravure printing by engraving a plurality of cells on the surface of a gravure cylinder, comprising: a rotating means for rotating the gravure cylinder in a main scanning direction; Carry signal generating means for generating a sinusoidal carry signal having a frequency and a constant amplitude; density signal generating means for generating a density signal whose level changes according to the gradation of image data to be provided; By engraving a density signal, an engraving signal generating means for generating an engraving signal, and by reciprocating vibration according to the engraving signal, a gravure cylinder rotating in the main scanning direction, a stylus for engraving a cell, A stylus feeding means for feeding the stylus in a sub-scanning direction orthogonal to the main scanning direction; A gravure engraving system comprising: a tone correction unit that corrects the tone of the original image data so that the area of the cell is linearly proportional to the change in the tone, and then applies the corrected tone signal to the density signal generating unit. . 2. The gradation correction means comprises: first calculation means for calculating the area of a cell to be engraved when the original image data is directly provided to the density signal generation means for each gradation; A second calculating means for calculating an area of the cell in a case where the area of the cell is linearly proportional to a change in gradation of the original image data for each gradation, based on a calculation result of the first and second calculating means hand,
3. The gravure engraving system according to claim 1, further comprising: a third calculating unit configured to calculate a correction value for each gradation value of the original image data.