JP2814842B2 - Printing stain inspection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing stain inspection apparatus for detecting a stain on a picture while printing the same picture by printing.

[0002]

2. Description of the Related Art While printing the same picture on a printing machine, the ink drops drastically, the ink jumps over, or the picture becomes faint due to the blurred ink. In addition, the background may be smeared with the ink spread over the entire paper rather than locally. As a method for detecting such stains, light is applied to a web (printing paper, film, or the like in the form of a strip),
A method of detecting dirt by detecting a change in the reflected light is used. In Japanese Patent Publication No. 4-24228, as a method of detecting a printing failure, a light source is received at a plurality of points, and the amount of light received at the light receiving point is compared with a reference value. There is disclosed a method for judging an error in a specific manner.

[0003]

When the web surface is exposed to light and the amount of reflection is measured to check the contamination of the web, a major factor causing a measurement error is a change in the amount of reflected light due to a variation in luminance of the light source. It is a change. Fluorescent lights, incandescent lamps,
As for a light source such as an LED, a luminance change occurs due to a change in ambient temperature, so that a measurement error occurs. In addition ,
When the dirt determination is performed by setting a dirt determination standard for each element, when the web meanders, the amount of light entering each light receiving element becomes 1
It changed for each picture, and it was erroneously determined to be dirty.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and provides a printing dirt inspection apparatus for performing a stable inspection by correcting a fluctuation of a light source and detecting a dirt irrespective of a meandering of a web. The purpose is to do.

[0005]

In order to achieve the above object, a rod-like light source installed in a web width direction which is a direction orthogonal to a moving direction of a web, and a web width for receiving light reflected by the web from the light source. A plurality of reflected light receiving elements disposed over the range of the web width in the direction, a light source light receiving element for receiving light from the light source, and a pattern for detecting one pattern area printed on the web Range detecting means, and the detected one
In the pattern range, the output of each of the reflected light receiving elements and
The output of the light source light receiving element was obtained, and the value obtained by dividing the integrated value of the output of each reflected light receiving element by the integrated value of the output of the light source light receiving element was added for the reflected light receiving element provided in a predetermined range. The apparatus includes a screen brightness equivalent value calculating means for calculating a screen brightness equivalent value, and a picture stain determining means for comparing the screen brightness equivalent value with a reference value to determine stain.

Further, the reflected light receiving element is divided into a plurality of blocks, the light source light receiving element is provided for each block, and the integrated value of the reflected light receiving element in the same block is set to the light source corresponding to this block. It is divided by the integral value of the light receiving element.

The light source is provided in the vicinity of the position where the web is rolled, and the reflected light receiving element can receive the reflected light from the web background over both ends of the width of the web.

[0008]

The same picture is repeatedly printed on the web and moved. The reflected light over the length of one picture from each reflected light receiving element arranged in the width direction of the web is integrated. Similarly, each reflected light receiving element from the light source light receiving element received light
The amount of received light over the same length of one picture is integrated. A value obtained by dividing the integrated value of the output of the reflected light receiving element by the integrated value of the output of the light source light receiving element for the reflected light receiving element provided in the predetermined range (the screen brightness equivalent value) is the predetermined value. It is a value obtained by correcting the change in the luminance of the light source and the change in the running speed of the web for one picture in the range of the web that generates the reflected light received by the reflected light receiving element within the range. The reason is that the light source luminance change is corrected by dividing by the integral value of the output of the light source light receiving element. When the moving speed of the web changes, the integrated value of the output of each reflected light receiving element also changes at the same time, and the integrated value of the light source light receiving element also changes. By dividing by the integral value of the output of the light receiving element, the change in traveling speed is corrected at the same time as the change in luminance.

The reflected light receiving element is divided into a plurality of blocks,
A light source light receiving element is associated with each block. The light source is arranged in a bar shape in the width direction of the web, and the reflected light receiving element is also arranged in the width direction of the web. Although the light source is rod-shaped, the brightness is not completely uniform over the width of the web. Therefore, by providing a light source light receiving element for checking the light source light for each block, it is possible to correct uneven brightness of the light source.

When the web meanders, the value obtained by integrating the output of one reflected light receiving element for one picture is the same as the picture itself, but the picture in the field of view of the adjacent reflected light receiving element deviated by meandering is within the field of view of the user. As it comes into the picture, it changes when the picture becomes the next picture. When the reflected light receiving element is narrowed down to a predetermined range within the web in the width direction of the web, the integrated value of the output of the reflected light receiving element within this range also changes. Therefore, the range of the inspection visual field width is extended beyond the width of the web to the background of the web as shown in FIG. 5, and the sum of screen brightness equivalent values of the entire inspection visual field width is obtained. The hatched area in the figure is the reflection surface of the web background. Even if the web is meandering and moves left and right in the figure, if the width of the web is constant and the inspection visual field width of the reflected light receiving element is constant, the total area of the hatched portions does not change. Therefore, the value obtained by dividing the integrated value of the output of the reflected light receiving element corresponding to the inspection visual field width by the integrated value of the output of the light source light receiving element, that is, the sum of the brightness equivalent values does not change even if the web is meandering. Thereby, the influence of the meandering of the web can be eliminated. Further, since the inspection is performed in the vicinity of the deflector roll, there is no fluctuation in the pass line of the web, so that a stable inspection with a constant distance between the web and the measuring unit can be performed.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the overall configuration of the present embodiment.
1 runs on the web in the direction of the arrow. Reference numeral 2 denotes a pattern, and the same pattern is printed on the web 1 at a constant pitch determined by the diameter of the plate cylinder 3. Reference numeral 4 denotes a blanket cylinder which prints on the web 1 while transferring the ink of the plate cylinder 3 to the blanket cylinder 4 and pressing the ink with the impression cylinder 5. Reference numeral 6 denotes a deflector roll for changing the running direction of the web 1. Reference numeral 7 denotes a measurement start detector, which indicates a reference position of the plate cylinder 3. That is, one picture 2 on the web 1
Indicate the positions of t1, t2, and t3 in FIG. Reference numeral 8 denotes an encoder that outputs a travel length pulse of the web 1. Reference numeral 9 denotes a measuring unit for measuring the stain data of the picture 2. Reference numeral 10 denotes a light source power source of the light source provided in the measuring unit 9. Reference numeral 11 denotes a data processing unit which calculates the stain on the picture 2 from the data of the measurement start measuring unit 7, encoder 8 and measuring unit 9. An operation unit 12 operates the data processing unit 11 by an operator.

FIG. 2 is a perspective view showing the structure of the measuring section 9. The fluorescent lamp 20 is used as a light source, and is turned on at a high frequency to suppress flicker of luminance. The fluorescent lamp 20 can irradiate almost ideal band-like light to the surface of the web 1 due to its rod-like shape, but there is a luminance change with time and a luminance change due to an ambient temperature. Reference numeral 21 denotes a light receiver, in which a plurality of light receiving elements are arranged in parallel with the fluorescent lamp 20 as reflected light receiving elements, for example, using an amorphous silicon photodiode array. Reference numeral 22 denotes a light source luminance change detection sensor, which is a light source light receiving element in which a plurality of light receiving elements are arranged in parallel with the fluorescent lamp 20. This is a fluorescent light
Reference numeral 20 is used to correct for slight uneven luminance distribution in the longitudinal direction. Reference numeral 23 denotes a partition plate for preventing light of the fluorescent lamp 20 from directly entering the light receiver 21. 24 is a signal processing unit.

FIG. 3 is a detailed view of the light receiver 21. (A) is a front view in which slits 25 are arranged at a constant pitch. One light receiving element 26 is provided in two slits 25.
3B, only the parallel light passing through the slit 25 in the XX section is incident on the reflected light receiving element 26. In order to make the parallel light as much as possible, the slit 25 is subdivided into two light receiving elements. Double the number. (C) shows the arrangement of the reflected light receiving element 26 on the printed circuit board 27 in the YY section.

FIG. 4 is a view showing an optical system of the measuring section 9.
The light of the fluorescent lamp 20 is reflected by the web 1 on the deflector roll 6 and enters the light receiving element 26 of the light receiver 21. Further, the direct light of the fluorescent lamp 20 enters the light source luminance change detection sensor 22.

FIG. 5 is a diagram showing the arrangement of the web 1, the deflector roll 6, the light source luminance change detecting sensor 22, and the light receiving element 26. The reflected light receiving element 26 is arranged in parallel with the deflector roll 6, and the web 1 as shown in the inspection field width.
Cover a range larger than the width of The reflected light receiving element 26 is divided into a plurality of blocks, and the light source luminance change detection sensor 22 is assigned to each block. The light source luminance change detection sensor 22 covers the reflected light receiving element 26 as shown in the figure. FIG. 5 shows an example in which the measuring unit 9 faces the deflector roll 6 as in FIG. 1. FIG. 6A shows the inspection field where the measuring unit 9 faces the intermediate position between the two deflector rolls 6. Is shown. FIG. 6B is a side view of FIG.

FIG. 7 is a block diagram showing the configuration of the signal processing unit 24 of the measuring unit 9. S1 to Sm are reflected light receiving elements 26 and S that faithfully convert a reflected light amount value that changes every moment into an electromotive force.
S1 to SSn are light source luminance change detection sensors 22 that faithfully convert the direct light of the fluorescent lamp 20 into an electromotive force and are constituted by light receiving elements. Reference numeral 30 denotes a preamplifier, which normalizes dark currents and variations in sensitivity of the reflected light receiving elements S1 to Sm by adjusting bias and gain to convert electromotive forces of S1 to Sm into voltage signals. An integrator 31 integrates the output signal of the preamplifier 30 for one picture. Reference numeral 32 denotes a sample-and-hold device, which holds an integrated value for one picture integrated by the integrator 31. Similarly, 33 is a preamplifier, 34 is an integrator, and 35 is a sample and hold device. 36 and 37 are multiplexers and 38 is a divider for dividing the value of the sample hold 32 by the value of the sample hold 35. 39
Amplifies the divided value for each of the reflected light receiving elements S1 to Sm with an amplifier. 40 is A / that converts an analog value to a digital value.
A D converter, 41 is a CPU, and 42 is a memory.

Next, the operation will be described. When the web 1 runs, the MS signal is output from the measurement start detector 7 attached to the plate cylinder 3 as a start timing signal as shown in FIG. This MS signal is at the position of the head of the plate cylinder 3 and, when printed on the web 1, corresponds to the start position of one picture as shown in FIG. Further, a web running length pulse is output from an encoder 8 attached to the deflector roll 6. The MS signal and the web running length pulse of the encoder 8 are sent to the data processing unit 11.

In the data processing section 11, the distance for each picture in the measuring section 9 by the web running pulse from the encoder 8 (FIG. 1)
L) is tracked. When the MS signal enters the measurement visual field, that is, when a in FIG. 8 enters the measurement visual field, a measurement start command is given from the data processing unit 11 to the measurement unit 9. The data processing unit 11 sequentially performs the distance tracking of L in FIG. 1 for each incoming MS signal, and outputs a measurement start command to the measurement unit 9.

The amount of reflected light changes every moment depending on the pattern 2 of the printed web 1 passing through the detection field of view of the measuring section 9 and its density. Each light receiving element S1 to S in FIG.
The output of m is represented by PA in FIG. This is the light receiving element Sk
And the change in print density within the visual field range. IA indicates a value obtained by integrating PA for one picture, that is, between t1 and t2. This means that the integral value of the lightness equivalent value including the print density in the visual field range of each light receiving element Sk can be regarded as a picture area in a single color. SHA in FIG. 8 indicates a value obtained by sampling and holding the output of the integrator 31. Therefore, the sample hold value of the integral value performed between t1 and t2 is shown between t2 and t3. The processing of PA, IA, and SHA is performed in parallel for each of S1 to Sm. PA for each element of S1 to Sm
In order to adjust the output level, first, black paper is placed on the measurement surface and the output from PA1 to PAm in FIG. 7 is adjusted to be zero. Adjust to a value.

Next, the outputs of the light source luminance change detection sensors SS1 to SSn for detecting the luminance change of the fluorescent lamp 20 shown in FIG. SS1
ＳＳSSn generate an electromotive force proportional to the intensity of the luminance of the fluorescent lamp 20. The preamplifiers PAS1 to PASn turn off the light source, adjust the bias so that the outputs of PAS1 to PASn become zero, and then turn on the light source to adjust the gain. When the web 1 of PA1 to PAm is blank, Normalization is performed so that a predetermined identical value of the output and the outputs of PA1 to PASn become the same output, so that the division operation can be performed at high speed and with high accuracy. The time constants of the integrators IAS1 to IASn at the next stage are the same as those of the integrators IA1 to IAm, and the integration range is between t1 and t2. The sample hold units SHAS1 to SHASn at the next stage of the integrator 34 hold the integrated value of the integrator. 9 is the output of the preamplifier 33, IA
S is the output of the integrator 34, and SHAS is the output of the sample and hold 35.

In FIG. 7, the CPU 41 holds the SHA of the signal measured by Sk by the analog multiplexer 36 in accordance with the timing of the MS signal.
k is selected, and the output of the SHASk 'holding the integrated value of the measurement signal of the corresponding light source luminance change detection sensor SSk' by the analog multiplexer 37 is output to the reflected light receiving element 26 and the light source shown in FIG. It is selected by a corresponding combination of the luminance change detection sensors 22. Divider 38 outputs MUX 36 to M
Divide by the output of UX37. Thereby, both the traveling speed correction of the web 1 and the luminance correction of the fluorescent lamp 2 can be performed at once.

An MS signal interval (t1 to
Since t2) is inversely proportional to the running speed of the web 1, the running speed of the web 1 can be obtained by measuring the interval between the MS signals.
Since the reset timing of the integrator 31 is performed by the MS signal, if the input of the integrator 31 is set to a constant value, the output of the integrator 31 is obtained as a value inversely proportional to the traveling speed of the web 1. Since the integration time is the same for both the reflected light receiving element Sk and the light source luminance detection sensor SSk ', the divided value is independent of the web speed.

The Sk measurement signal corrected by the divider 38 is converted into digital data by an A / D converter 40 through an amplifier 39 and stored in a memory 42.

The number of light receiving elements S1 to Si for measuring the range in which the luminance is to be corrected by SS1 is equal to the number i of the light receiving elements S1 to MUX37.
Each time the selection data of X36 is changed, the division result of the divider 38 is A / D converted and stored in the memory 42. Then SS
When 2 is within the range for luminance correction, the MUX 37 selects SS2, and the MUX 36 sequentially selects Si + 1 to S2i.
The processing up to Sn is performed in this way, and stored in the memory 42. All data stored in the memory 42 is sent to the data processing unit 11.

The data processing unit 11 adds all the correction data of S1 to Sn to obtain data of one entire picture. When the operator determines that the printing state is good, all the data of the one design surface S1 to Sn measured at that time are added and stored as a reference value. The web 1 passing through the measuring surface of the measuring device 9 is measured for one picture length, compared with a reference value, and a deviation is calculated. The deviation is within a deviation allowable range set on the operation panel surface of the operation unit 12. It judges whether or not it is within the range, and outputs a warning signal if it exceeds the allowable range.

The change in ink splashing, ink fading, and background stain is a very small value with respect to the value obtained by adding all the data. Since the calibration is performed for each element and the division is normalized by division, it is possible to identify even if there is a small change in the brightness equivalent value with respect to the reference picture. As a result, the allowable deviation value can be set small.

[0027]

As is apparent from the above description, the present invention corrects the output of the light receiving element that receives the reflected light from the web by using the light source luminance change detection sensor, and changes the light source and the speed of the web. Can be detected. In addition, by extending the monitoring range of the light receiving element beyond the width of the web, the influence of the meandering of the web can be eliminated and the contamination can be determined.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is a perspective view of a measurement unit.

FIG. 3 is a detailed view of a light receiver.

FIG. 4 is a diagram illustrating an optical system of a measurement unit.

FIG. 5 is a diagram showing an arrangement relationship between a web, a deflector roll, a light source luminance change detection sensor, and a reflected light receiving element.

FIG. 6 is a diagram illustrating a relationship between a web, a deflector roll, a measurement unit, and an inspection field width.

FIG. 7 is a block diagram illustrating a configuration of a signal processing unit of the measurement unit.

FIG. 8 is a diagram illustrating a state in which the output of a light receiving element that receives reflected light from a web is integrated through a preamplifier and held.

FIG. 9 is a diagram showing a state in which the output of the light source luminance change detection sensor is integrated through a preamplifier and held.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Web 2 Pattern 3 Plate cylinder 6 Deflector roll 7 Measurement start detector 8 Encoder 9 Measurement unit 11 Data processing unit 20 Fluorescent lamp 21 Receiver 22 Light source luminance change detection sensor 24 Signal processing unit 26 Reflected light receiving element 30, 33 Preamplifier 31 , 34 Integrator 32, 35 Sample hold 36, 37 Multiplexer 38 Divider 39 Amplifier 40 A / D converter 41 CPU 42 Memory

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideo Hamanaka 2951-4 Ishikawa-cho, Hachioji-shi, Tokyo Nireco Co., Ltd. (56) References JP-A-63-116853 (JP, A) (58) Fields investigated Int.Cl. ⁶ , DB name) B41F 33/14 G01N 21/89

Claims (3)

(57) [Claims] 1. A bar-shaped light source installed in the web width direction is a direction perpendicular to the moving direction of the web, range of web width in the web width direction for receiving the light reflected on the web from the light source
A plurality of reflected light receiving elements installed over the surroundings; a light source light receiving element for receiving light from the light source; a picture area detecting means for detecting one picture area printed on the web; In the pattern range, each reflected light receiving element
The output and the output of the light source light receiving element are obtained, and the reflected light receiving element provided in a predetermined range is obtained by dividing the integrated value of the output of each of the reflected light receiving elements by the integrated value of the output of the light source light receiving element. A print stain inspection apparatus comprising: a screen brightness equivalent value calculating means for calculating the added screen brightness equivalent value; and a picture stain determining means for determining the stain by comparing the screen brightness equivalent value with a reference value. 2. The method according to claim 1, wherein the reflected light receiving element is divided into a plurality of blocks, the light source light receiving element is provided for each block, and an integrated value of the reflected light receiving element in the same block is assigned to the light source corresponding to the block. 2. The printing smear inspection apparatus according to claim 1, wherein the division is made by an integral value of the light receiving element. 3. The method according to claim 1, wherein the light source is provided near a position where the web is rolled, and the reflected light receiving element can receive reflected light from the web background over both ends of the width of the web. 3. The printing stain inspection apparatus according to claim 1, wherein