JP3307992B2 - Picture area ratio measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a pattern area ratio of a printing plate.

[0002]

2. Description of the Related Art Conventionally, a pattern area ratio measuring device irradiates a printing plate with light, measures the amount of reflected light, and measures the pattern area ratio of the printing plate based on the measured value.
It is necessary to recognize the relative position between the printing plate and a detection head having an irradiation device (such as a fluorescent lamp) and a light receiving sensor array (such as a photodiode). This is because when measuring the image area ratio of each divided area corresponding to each of the plurality of ink adjusters of the printing press on the printing plate, the output value of each light receiving sensor indicates the light amount from any position on the printing plate. It is necessary to know the value.

In the prior art, as described in Japanese Patent Application Laid-Open No. 2-77609, in order to recognize the relative position between the detection head and the plate, the plate is positioned at a specific position by using a specially provided setting mechanism. I was trying to do it.

[0004]

However, in the prior art, the above-described plate positioning setting mechanism complicates the entire apparatus, and requires a plate positioning time, which causes a reduction in the operation rate. Was.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pattern area ratio measuring method capable of measuring a pattern area ratio even when the printing plate is not positioned at a specific position with respect to the supporting means.

[0006]

SUMMARY OF THE INVENTION According to the present invention, there is provided a plate supporting means for supporting a printing plate, an irradiating device for the printing plate arranged in a specific positional relationship with respect to the plate supporting means, and A detection head having a sensor array for receiving reflected light from the printing plate is provided; and the detection head and the printing plate are relatively moved, and the output value from each sensor constituting the sensor array is moved during the relative movement. The output value stored in the storage device is stored in the storage device for each predetermined relative movement, and the inclination state of the plate with respect to the sensor row direction is detected, based on the detected inclination state and the known dimensions related to the plate. From the group, an output value for an area corresponding to each of the plurality of ink adjusters of the printing press in the printing plate is selected for each of the areas, and a pattern of the printing plate for each area is selected based on the selected output value. In the image area ratio measuring method for determining by calculation the factor, to previously obtain a relation between the ratio and the sensor output value of the uncoated portion of the plate occupying the field of view of the pre-sensor relative movement Direction certain stomach orthogonal thereto from the rectangular sensor array direction certain have at least two positions was set to direction output value group definitive in the direction perpendicular thereto, of the plate at least 1
The output values from the sensors facing the two edges are respectively recognized, and the ratio of the unoccupied portion in the visual field range of the sensor is determined from the recognized output values and the relationship, and the ratio and the detection position of the sensor are determined. , The positions of at least two points on the edge are calculated, and the linear direction formed by the at least two points is recognized as the inclination direction of the printing plate.

[0007]

The position of at least two points on the edge of the printing plate is calculated based on the relationship between the ratio of the unprinted portion of the printing plate to the sensor's field of view and the sensor output value.
The direction of the straight line formed by the points is recognized as the inclination direction of the plate, and the inclination state of the plate is obtained. Then, based on the tilt state and the known dimensions of the printing plate, sensor output values from the respective regions of the printing plate corresponding to the respective ink adjusters are selected for each of the regions, and a pattern for each region is selected based on the selected output value. Calculate the area ratio.

[0008]

FIG. 1 is a schematic diagram showing a picture area ratio measuring system, FIG. 2 is a block diagram showing a picture area ratio measuring system,
FIG. 3 is a schematic diagram showing a pattern area ratio detection head, FIG. 4 is a schematic diagram showing a printing plate, a sensor row, and a reference plate, and FIG. FIG. 6 is a schematic diagram showing the relationship between the ratio K of the unprinted portion of the printing plate occupying the visual field range of the sensor and the sensor output value t. FIG. 7 is a diagram showing the detection position of the sensor and the position of the printing plate. FIG. 8 is a schematic diagram showing a method for calculating the positions of two points on an edge of a printing plate from output values of a sensor facing the edge of the printing plate, and FIG. 9 is finding a position of one corner of the printing plate. FIG. 10 is a schematic diagram showing the principle of calculating the position of each region of the printing plate, and FIG. 11 is a schematic diagram showing the principle of correcting the amount of received light at the periphery of the printing plate region. In FIG. 1, reference numeral 11 denotes a developing device, 1
2 is a picture area ratio measuring device.

The developing device 11 develops and fixes the printing plate 13 on which the image of the original film is printed. 11A is a developing solution supply nozzle, 11B is a washing nozzle, 11C is a fixing solution supply nozzle, 11D is a washing nozzle, and 11E is a drying roller. At this time, as shown in FIG. 3, the printing plate 13 is provided with a calibration mark 13A used for measuring the pattern area ratio and an identification mark 13B such as a bar code on its plain portion 13C.

The picture area ratio measuring device 12 includes a printing plate transport device 14, a detecting head 16, a storage device 17, and an arithmetic device 18.

The plate carrying device 14 functions as a plate supporting means for supporting the plate 13 and serves to transfer the plate 13 to the detection head 1.
6, and also has a function as a moving device that moves relative to 6.

Specifically, as shown in FIG. 1, the plate carrying device 14 places the plate 13 on a plurality of rotating rollers 21 arranged side by side, supports the plate 13, and carries the plate. In FIG. 1, 21A is an encoder.

At this time, the plate carrying device 14 is provided with an air chamber 22 which is substantially closed except for the plate carrying surface region below and outside the plate carrying surface formed by the rotating roller 21. Further, the plate transport device 14 includes an exhaust fan 28 at the bottom of each air chamber 22. Exhaust fan 28, during transportation of the printing plate 13, air pressure acting on the surface opposite to the contact surface of the rotating roller 21 in the plate 13, Daito than pressure acting on the surface side of the rotating roller 21 Air chamber 2
Adjust the pressure inside 2. Thus, plate transport device 14, by the difference in pressure acting on both surfaces of the plate 13, will be pressing the plate 13 on the side of the rotating roller 21, as a result, the plate 13 and the rotary roller 21 The contact resistance between them is increased, and the printing plate 13 can be transported reliably without slippage.

The detection head 16 is disposed above the plate transporting device 14 in a specific positional relationship, and as shown in FIG. 3, an irradiating device 31 for the plate 13 and light reflected from the plate 13. Is provided. Accordingly, the detection head 16 outputs the light reception value received from the reflected light of the corresponding detection area by each sensor 33 of the sensor array 32 for each predetermined relative movement amount of the printing plate 13 by the printing plate transport device 14. it can. In FIG. 3, A to E defined in the printing plate 13 are areas corresponding to a plurality of ink adjusters of the printing press.

In the measurement zone of the printing plate 13 with which the sensors 33 of the detection head 16 face each other, below the passing line of the printing plate 13, as shown in FIGS.
Reference plate 102 on which 01 (measurement object for correction) is installed
Is provided. Therefore, each sensor 33 of the detection head 16 measures the amount of reflected light from the correction reference plate 101 before passing through the plate 13, and measures the amount of reflected light from the plate 13 when passing through the plate 13. The correction reference plate 101 is for correcting a measurement error caused by a difference in output characteristics between the sensors 33, and is configured to give the same reflected light amount at any position with the same projected light amount.

The storage device 17 stores each sensor 3 of the detection head 16 when the printing plate 13 is relatively moved with respect to the detection head 16.
3 is stored for each predetermined relative movement amount of the printing plate 13.

At this time, the detection head 16 also functions as a plate inclination detecting device, and detects the inclination direction of the plate 13 with respect to the direction of the sensor array 32 as shown in the following (A) to (C). The inclination state of the printing plate 13 which is conveyed by the conveying device 14 as described above and whose reflected light is received by the detection head 16 can be detected.

(A) A reference plate 101 as described above is provided at a position facing the sensor array 32 and below the surface of the plate 13 for carrying the plate.
Is laid, and the amount of reflected light received by the sensor 33 is
Reference plate 101> solid portion 13C ≧ picture portion ≧ calibration mark 13A.

Therefore, one sensor is selected as a specific sensor 33A from the sensor array 32 of the detection head 16 (see FIG. 4). Then, the area of the uncoated portion 13C of the printing plate 13 is gradually changed with respect to the visual field range of the sensor 33A (see FIGS. 5A to 5C), and the sensor output value t at each time is stored in the storage device 17. (See FIG. 6).

In FIG. 5, the visual field range of the specific sensor 33A is S ₀ = a × b, and the distance from the sensor center o to the lower edge 13E of the printing plate 13 is y. FIG. 5A shows the sensor 3.
There is no solid portion 13C in the field of view of 3A (the occupancy of the reference plate 101 is 100%), and in FIG. 5B, the solid portion 13C exists in the field of view of the sensor 33A. Finally, as shown in FIG. 5C, the sensor output value t is increased until the solid portion 13C occupies the entire visual field range of the sensor 33A (the occupancy of the reference plate 101 is 0%).
Record.

[0021] In FIG. 6, y = y _a is a state of FIG. 5 (A), t = t 0, y = y i is the state of FIG. 5 (B), t = t i, y = 0 Is the sensor center o is the lower edge 13E
A state that matches _{a, t = t s, y =} -y a Figure 5
(C) a state of a t = t _n.

(B) Next, the calculation device 18 obtains the light amount change rate K (see FIG. 6). This K is

(Equation 1) (A is the reflected light amount value t ₀ of the reference plate 101, and B is the solid portion 13
The reflected light amount values t _n and C of C are calculated by an arithmetic expression of each sensor output value t _i ). When C = A, that is, when the entire visual field range is the reference plate 101, 0% and C = When B
That is, since the visual field range is 100% when the entire visual field range is the plain area 13C, the light amount change rate K represents the ratio (occupancy rate) of the plain area 13C to the visual field range of the sensor 33.

The light amount change rate K obtained by calculation for each sensor output value and y (the printing plate 1 from the center o of the sensor 33A)
3 (distance to the lower edge 13E) in a graph (see FIG. 6). So we know that y is + y
_a, although becomes quadratic curve as close to -y _a, in the detection area W of the sensor 33A (detection coverage area of a single sensor 33 at the time of the image area ratio measurement), K = αy + β
(Α, β can be obtained from the graph). Therefore, K = αy + β

(Equation 2) Becomes

Therefore, if the sensor 33 facing (facing) the lower edge 13E of the printing plate 13 is found, the output value t of the sensor 33 is substituted into the equation (1) as C, and the y value, that is, the sensor value is obtained. Lower edge 13 of plate 13 from center o of 33
The distance y to E will be known.

(C) How to find the sensor 33 facing the lower edge 13E of the printing plate 13 The pattern area ratio measuring device 12 detects the leading edge 13F of the printing plate 13 upstream of the detection head 16. The sensor 103 is provided (see FIGS. 1 and 2). The sensor 103 is also used for detecting the trailing edge 13R of the printing plate 13. Then, based on the output signal of the tip detection sensor 103, the detection head 16 starts operating, and the plurality of light receiving sensors 33 included in the detection head 16 start taking in the reflected light amount value at the pitch P.

The amount of movement of the printing plate 13 from the time when the leading edge detection sensor 103 detects the leading edge 13F of the printing plate 13 is detected by an encoder 21A or the like of the printing plate transport device 14.

In this way, every time the printing plate 13 moves by the pitch P, the output value t of each sensor 33 is stored in the storage device 17 together with the coordinate value (X _i , Y _i ) of the detected position.

In FIG. 7, an XY axis having an origin opposite to the lowermost sensor 33 of the sensor array 32 of the detection head 16 is set. Here, the printing plate 13 actually moves, but assuming that the sensor array 32 moves, the detection head 16 moves the distance M from the time when the leading edge detection sensor 103 detects the leading edge 13F of the printing plate 13.
After the movement, the first sensor output value is captured, and thereafter, the same capture is performed every time the sensor output value is moved by the pitch (detection interval) distance P. Note that these captured data are stored together with the detection positions of the sensors 33 as described above.

Next, a preset data fetch position,
From the output value of each sensor 33 at the detection position of S ₁ and S ₂ which in this example is two points set in a relative movement direction of the plate 13 and the sensor array 32, under the plate 13 as follows edge 13E Is calculated.

[0030] First, in the detection position S _1, the sensor array 32
Bottom 0th output value d ₀ of the sensor (the (indicating the amount of received light value from the reference plate 101) as the denominator, the output value d _i of each sensor
Is performed with 分子 as the numerator. The sensor where this quotient first falls below the predetermined set value Z is set to the lower edge 1
It is assumed that the sensor 33 faces 3E. In FIG. 8, the output value d ₃
This is the third sensor. Then, to calculate the distance y ₃ to the bottom edge 13E from the center o of the third sensor using the equation (1). In addition, y ₃ is (1) where A is d
₀ , B is d ₄ (the output value of the 4th sensor next to the 3rd sensor,
Or d ₅ Any Good), and the C is a value obtained by substituting the d _3. Similarly, in the detection position S _2, the sensor facing the lower edge 13E, found to be number 2 sensor, it can be obtained y ₂ from equation (1).

By the way, since M, P, and the sensor interval l are known, the sensor center o of the third sensor at the detection position S _{1 and} the sensor center o of the second sensor at S ₂ on the XY axes.
XY coordinates are obtained. Since y ₂ and y ₃ have been obtained as described above, the lower edge 13
E indicates the coordinates of points Q and R (see FIGS. 8 and 9) corresponding to the third sensor and the second sensor at the detection positions S ₁ and S ₂ , and the lower edge 13E exists on a straight line passing through these two points Will do.

Next, referring to FIG.
Since the distance between 3 and the detection head 16 is known at the design stage, the coordinate value of the point U on the leading edge 13F detected by the leading edge detection sensor 103 on the coordinate axis is also known. Then, a straight line passing through the point U and orthogonal to the straight line QR is determined by arithmetic, and it can be seen here that the intersection V of the two straight lines is one corner of the printing plate 13 (see FIG. 9).

The intersection point V which is one corner of the printing plate 13 and the printing plate 1
If the inclination state of the printing plate 3 is known, various dimensions (the size of the printing plate 13, the size of the picture portion area, the size of the divided area, etc.) of the printing plate 13 are input as shown in the following (1) and (2). By using the size, the position of the calibration mark 13A, etc.), the position of the printing plate on the coordinate axis shown in FIG. 7 can be found as shown by a solid line, and the pattern is obtained by using the sensor output value located in the solid line. The area ratio can be obtained for each divided region.

(1) First, the areas A to E of the printing plate 13 in the inclined state and the position of the calibration mark 13A are calculated as follows.

In the state as shown in FIG. 10A where the printing plate 13 is not inclined, for example, the corner a of the printing plate 13 is set at the coordinate origin (0, 0) based on the known dimensions of the printing plate 13 which has been input in advance. )
, For example, four corner positions (x ₁ , y ₁ ) of the area A and the calibration mark 13A, respectively.
(X ₄ , y ₄ ) to (x _k , y _k )... (X _n , y _n ) can be calculated as coordinate values.

Further, as shown in FIG. 10B, when the plate 13 is rotated by an angle θ about the corner a, the four corner positions of the area A and the position of the calibration mark 13A are converted by coordinate conversion. It can be calculated as a coordinate value.

Further, as shown in FIG.
When the corner a of the printing plate 13 shown in FIG. 10B is translated from the coordinate origin (0, 0) to the coordinate (0, k), the four corner positions of the area A are similarly converted by the coordinate conversion. The position of the calibration mark 13A is represented by coordinate values (X ₁ , Y ₁ ) (X ₄ , Y ₄ ), (X _k , Y _k ).
It can be calculated as (X _n , Y _n ).

(2) For the printing plate 13 in the inclined state, after calculating the positions of the respective areas A to E and the calibration marks 13A as described above, the pattern area ratio of each area is obtained as follows. . The area A will be described.

The area A has four points (X ₁ , Y ₁ )... (X ₄ , Y
_This is the area enclosed by ₄ ). Therefore, a light reception value corresponding to the coordinate values existing in the area A is selected from the light reception value group stored in the storage device 17 based on the coordinate values stored together with the respective light reception values. The light reception value for the calibration mark 13A is selected in the same manner.

The light receiving value group selected as the light receiving value in the area A is averaged, and the pattern area ratio of the area A is calculated from the average light receiving value and the calibration value of the calibration mark 13A.

In the above embodiment, for example, the region A
In the calculation of the pattern area ratio, first, four corner coordinate values (X ₁ , Y ₁ )... (X ₄ , Y ₄ ) of the area A are obtained.
Next, the light receiving value corresponding to the coordinate value in the area surrounded by the coordinate values is selected from the storage device 17, and the pattern area ratio is obtained from the average value of the selected light receiving values.

However, in the case of the above embodiment, as shown in FIG. 11, in calculating the area A, the coordinate values (X _p , Y _p )
The coordinate value (X _p , Y _p ) is outside of the area A, although the light-receiving value of is a part of the detection area (the range of one square) belongs to the area A. It is not used at all for the calculation of the pattern area ratio of the area A. Conversely, the received light value of the coordinate values ( _Xr , _Yr ) is calculated as the pattern area ratio of the area A as it is, even though a part of the detection area is out of the area A. It is to be used for.

Therefore, in order to improve the calculation accuracy of the pattern area ratio, the selection of the received light value from the storage device 17 is preferably performed as follows. That is, in consideration of the detection area of each sensor, if a part of the detection area is within the area A, the received light value is used when calculating the picture area ratio. However, weighting is performed.

The above weighting is performed, for example, by using coordinate values (X _p ,
For Y _p), the ratio pa / (p _a + p of the area belonging to the area A relative to the detection area _{(p a + p 0) (} p a)
₀ ) is multiplied by the light receiving value of the coordinate value (X _p , Y _p ), and the result of the multiplication is used for calculating the pattern area ratio.

Further, the coordinate values (X _r, Y _r) For the proportion of the detection area (r _a + r ₀₎ area which belongs to the area A with respect to (r _a) ra / a (r _a + r _0), the coordinates The light receiving value of the value ( _Xr , _Yr ) is multiplied, and the result of the multiplication is used for the calculation of the pattern area ratio.

Although the calculation accuracy of the pattern area ratio is reduced, the coordinate values (X _p , Y _p ) and (X _r , Y _r ) are used in order to simplify the calculation process and to maintain a certain accuracy. For example, the light receiving amount of those coordinate values may be multiplied by, for example, 50%, and the result of the multiplication may be used for the calculation of the pattern area ratio.

Next, the operation of the present embodiment will be described.
Solid portion 13C of printing plate 13 occupying the field of view of sensor 33
The printing plate 1 is determined based on the relationship between the ratio of the portion and the sensor output value.
The positions of at least two points S ₁ and S ₂ on the edge 13E of the third plate 13 are calculated, and the linear direction formed by the at least two points S ₁ and S ₂ is recognized as the inclination direction of the plate 13, and Obtain the tilt state. Then, based on the tilt state and the known dimensions of the printing plate 13, sensor output values from the respective regions A to E of the printing plate 13 corresponding to the respective ink adjusters are selected for each region, and based on the selected output value. The picture area ratio for each area is calculated.

In the present embodiment, the inclination direction of the printing plate 13 is determined based on the sensor output values of the _two detection positions S ₁ and S ₂ , but the sensor output values of three or more detection positions are used. The determination may be made by performing arithmetic processing (for example, using a least squares method).

[0049]

As described above, according to the present invention, it is possible to provide a pattern area ratio measuring method capable of measuring the pattern area ratio even when the printing plate is not positioned at a specific position with respect to the supporting means. .

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a pattern area ratio measurement system.

FIG. 2 is a block diagram showing a pattern area ratio measurement system.

FIG. 3 is a schematic diagram showing a pattern area ratio detection head.

FIG. 4 is a schematic diagram showing a printing plate, a sensor array, and a reference plate.

FIG. 5 is a schematic diagram showing a state in which the area of the uncoated portion of the printing plate is changed with respect to the visual field range of the sensor.

FIG. 6 is a schematic diagram showing the relationship between the ratio K of the unprinted portion of the printing plate in the field of view of the sensor and the sensor output value t.

FIG. 7 is a schematic diagram illustrating a relationship between a detection position of a sensor and a position where a printing plate exists.

FIG. 8 is a schematic diagram showing a method for calculating the positions of two points on an edge of a printing plate from an output value of a sensor facing the edge of the printing plate.

FIG. 9 is a schematic diagram showing a method for determining a position of one corner of a printing plate.

FIG. 10 is a schematic diagram showing the principle of calculating the position of each area of the printing plate.

FIG. 11 is a schematic diagram showing the principle of correcting the amount of received light at the peripheral edge of the printing plate.

[Explanation of symbols]

 Reference Signs List 12 picture area ratio measuring device 13 printing plate 13E edge 14 printing plate transport device 16 detection head 17 storage device 18 arithmetic device 32 sensor array 33 sensor

Continuation of front page (56) References JP-A-4-15842 (JP, A) JP-A-2-77609 (JP, A) JP-A-62-2229008 (JP, A) JP-A-61-122510 (JP) , A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01B 11/00-11/30 102 B41F 31/00-35/04 G03F 5/00

Claims (1)

(57) [Claims] 1. A printing plate supporting means for supporting a printing plate, a device for irradiating the printing plate with a specific positional relationship with respect to the printing plate supporting means, and receiving reflected light from the printing plate. A detection head having a sensor array that performs relative movement between the detection head and the printing plate, and outputs the output value from each sensor constituting the sensor array to the storage device at each predetermined relative movement during the relative movement. In addition to detecting the inclination state of the printing plate with respect to the sensor row direction, based on the detected inclination state and the known dimensions related to the printing plate, printing on the printing plate is performed based on the output value group stored in the storage device. An output value for an area corresponding to each of the plurality of ink adjusters of the printer is selected for each area, and a picture area ratio of a printing plate for each area is calculated based on the selected output value. In pattern area ratio measuring method, to previously obtain a relation between the ratio and the sensor output value of the uncoated portion of the plate occupying the field of view of the pre-sensor relative movement Direction certain <br/> physician direction towards orthogonal thereto sensor array direction certain have at least two positions have set from the output value group definitive in the direction perpendicular thereto, the output value from the sensor face at least one edge of the plate as well as cognitive respectively, From the perceived output values and the relationship, the ratio of the solid portion in the visual field range of the sensor is determined, and the positions of at least two points on the edge are calculated based on the ratio and the detection position of the sensor. A method of measuring a pattern area ratio, characterized in that a linear direction formed by at least two points is recognized as an inclination direction of the printing plate.