JPH09300589A - System for dynamic reflection density measurement and control for rolled band printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the reflection density accurate and reliable by analyzing a digitized image containing a first color, then generating the reflection density value of the digitized image and correcting the reflection density by a light scattering compensation signal and a light discontinuation compensation signal. SOLUTION: Light scattering data to be used to compensate for a light scatter is obtained by slowly moving a CCD matrix sensor 30 crosswise when the light passes scattered as a slow pass in the start mode. If a few number of passes are made in order to obtain light scattering data, the obtained digitized image is analyzed, then the data obtained by the light scatter pass is averaged by counting the total number of white pixels in the entire image, and the percentage of the white pixels is sought to store it in memory. This percentage data is used for compensating for reflection density data measured when analyzing the refection factor of each of the color blocks using each of keys during printing operation. After the operation in the start mode, it is switched to the execution mode and the CCD matrix sensor 30 is transferred across the rolled band on a printing press. In this case, the CCD matrix sensor 30 is synchronized with the speed of the rolled band to obtain the reflection density data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a method and apparatus for measuring the reflection density of a print pattern of ink in a predetermined area and using the measurement result to control the supply of printing ink by a printing press.

[0002]

2. Description of the Related Art A web (web) printing machine of the type that prints full-color magazines and other printed matter at high speed generally has a large number of printing stations, and when the web passes through the printing machine, each station Print different colors on the web. Such printing machines generally have a plurality of printing stations, which typically print in cyan, magenta, yellow and black respectively. Print quality depends not only on the proper alignment of each color printed by each printing station, but also on the amount of ink printed for each color by the printing station and the resulting distribution pattern.

The distribution of the ink transferred to the web during the printing operation is typically referred to as the "key," which varies depending on the type of printing machine, but is typically approximately 1-2 inches apart. Controlled by a number of ink zone control mechanisms spaced across the width of the press at, these keys effectively define a zone that limits the amount of ink available for transfer to the web. For each color printed, the amount of ink transferred at each key position on each printing station can be very small or relatively large, depending on the perceived color in the printed image. As is well known to those skilled in the art, for women dressed in bright red, which occupy a significant portion of the area of impression, red is a combination of magenta and yellow, so a large amount of magenta and yellow Ink needs to be applied at both magenta and yellow printing stations. That is, each key in the red garment area is controlled to give more of their ink than in the other areas of the printed impression. In general, the transfer of ink printed at each printing station is important to achieve the desired perceived color in the resulting product.

In the operation of a full-color printing machine, the reflection density of the final printed product is measured using a small handheld densitometer and the quality of the final finished product is checked to confirm the quality of the actual print (eg page 1 of a magazine). It has long been practiced to print some test targets of each color of ink on the outer area. Such a densitometer gives readings in the range of approximately 0.5 to 2.5, with higher values indicating lower reflectance and closer to black. Such densitometers are extremely sensitive to operation and often must be calibrated to give reliable reflectance density readings. After setting up the printing operation, the printer must take samples at regular intervals during the printing press run and measure the reflection density to see if the ink transfer has changed. If so, adjust the press appropriately,
Match the measurement result with the desired value. It is also known in the art that printing press adjustments do not result in immediate changes in ink transfer. For example, adjusting one ink key may affect adjacent keys.

[0005]

It has been recognized for many years that it would be desirable to have a system that could measure the transfer of ink printed by a printing press on a web by means of the printing press. Attempts have been made to provide such systems, but due to the dynamic nature of the web printer, such attempts have not been successful.

Accordingly, a primary object of the present invention is a system for measuring the quality of a predetermined area printed on a web by a high speed web printer, the improved system being capable of making such measurements while the press is in operation. To provide.

Another object of the present invention is that the printing machine is operable to provide a reflection density value for each of several color inks while the printing machine is operating at high speeds, and It is to provide an improved system in which the values are accurate and reliable.

It is another object of the present invention to be operable to provide a reflection density value for each of several colored inks while the printing machine is operating at high speeds, and yet the reflection density value thereof. To provide an improved system that is accurate and reliable.

Another object of the present invention is to use a CCD matrix sensor and strobe to obtain a matrix image of the web and to provide a test print area containing various color blocks printed by the individual printing stations of the printing press. It is an object of the present invention to provide an improved reflection density measuring device which analyzes the obtained image and obtains the reflection density value for each block.

Yet another object of the present invention is to provide an improved apparatus which allows real-time analysis of reflection density for acquired pixel data while the printing machine is running at high speed.

Another object of the present invention is to print a test print area containing a color block of each color printed by a color station on the web and to obtain a separate reflection density value for each color at each key position. It is an object of the present invention to provide an improved device in which a test print area is printed adjacent to each key position on the printing machine, as required by the above, thereby providing extremely reliable and accurate reflection density values. The test print area may include a solid (solid) color block, a shaded (screen) color block, a combined shaded and solid color block, and an overprinted multi-solid color block.

Another object of the present invention is to acquire a pixel data image during operation of the printing machine, divide the image into three separate channels, red, green and blue, and obtain the resulting image digitally for each channel. It is an object of the present invention to provide an improved device which can be analyzed after being converted into an accurate reflection density value for each color of cyan, magenta, yellow and black to be printed.

Yet another object of the present invention is to provide an improved apparatus which employs a very sophisticated compensation and calibration scheme so that it is extremely reliable and accurate in determining reflection density values. The attendant objectives are to compensate for changes in the intensity and color temperature of a particular strobe firing and for the discontinuity of the strobe light distribution on the winding from which the image is taken. Another attendant objective is to calibrate the digitized part of the device to minimum and maximum reflectance values using very highly reflective or white and very low reflective or certified black standards, It is to ensure the consistency of calibration over time.

A related object is to provide a digitized image of the analog image obtained by the CCD matrix sensor and analyze the digitized image pixel by pixel during various operations of the device. Such analysis allows the device to neglect dust spots and other smears virtually pixel by pixel during various analyzes performed by itself, as well as the geometrical shape of the shape and screen dimensions contained in the resulting image. A measurement can be made.

Other objects and advantages will be apparent from the following detailed description with reference to the accompanying drawings.

[0016]

According to a first aspect of the present invention, an amount of ink of a first color that can be transferred to a web at positions spaced apart from each other across a width of a web printer in a printing operation. What is claimed is: 1. A roll band printer having a controllable ink zone control mechanism and a printing roller for transferring ink to the roll band, wherein the plate roll is attached to the roll plate. Using a color block set having a non-printing region extending in the lateral direction, the roll printing machine being substantially arranged at each of the mutually spaced positions on the roll, and using at least the color block set having the first color, Within a predetermined range in a dynamic reflection density measurement control system for a web printer, which measures the reflection density of the at least first color printed on the web moving during operation of the web printer. Consisting of multiple pixels with intensity values of Image acquisition means for acquiring a digitized image of a predetermined size of the winding strip, memory means for storing the digitized image, strobe means for illuminating at least a predetermined region of the winding material at the time of ignition, and the digital Calibration means for calibrating the image acquisition means by providing predetermined values for high and low light reflectance levels of the image, and at least a portion of one of the color block sets located in the acquired digitized image. Compensation means for measuring the presence and intensity of the printed matter and generating a light scatter compensation signal for compensating for the presence of the printed matter which affects at least the measured reflection density of said first color, and stored in said memory means , Analyzing the acquired digitized image of a surface with a uniform reference, and analyzing the digitized image to obtain a composite image of the entire digitized image acquired upon ignition of the strobe means. And a processing means for generating a light discontinuity compensation signal for compensating the non-uniform illumination between the plurality of positions, the processing means comprising at least the first color. Is analyzed to generate a reflection density value of the digitized image, and the reflection density value is corrected by the light scattering compensation signal and the light discontinuity compensation signal.

In a second aspect based on the first aspect, the image acquisition means includes charge coupled device (CCD) matrix sensor means suitable for acquiring the digitized image.
The CCD matrix sensor means has a lens and a separating means for separating light passing through the lens into three paths having red, green and blue lights, respectively. The CCD matrix sensor means comprises the separating means. Separated by 3
It is characterized by having three channels corresponding to one path, each channel outputting an image matrix of a corresponding color.

In a third aspect based on the second aspect, the CCD matrix sensor means and the strobe means are mounted to obtain a digitized image of a desired region of the roll, and the CCD matrix sensor means is mounted. And carriage means for moving the strobe means and the strobe means across the width of the winding body.

In a fourth aspect based on the second aspect, the intensity and the color of the illumination generated at the time of ignition by the strobe means are measured, and a strobe intensity signal indicating the measured intensity and color is generated. The processing means is characterized in that the processing means uses the strobe intensity signal to generate the reflection density that compensates for variations in intensity and color during strobe firing.

In a fifth aspect based on the first aspect, the color block set comprises a solid color block, a halftone block, a block combining solid and halftone shade, and an overprinted solid block. Characterize.

In a sixth aspect based on the first aspect, the memory means has a high reflection level of a pixel in a digitized image with respect to a light-scattering compensation signal, which becomes a substantially asymptotic curve when plotted together. The relationship between the distances from the color block of interest in the digitized image is shown, and the light scattering compensation data having a nearly asymptotic curve by plotting these relationships together is characterized.

In a seventh aspect based on the first aspect, the processing means analyzes substantially all pixels of the digitized image of the color block set, and outputs at least one light scattering compensation signal relating to the color block set. The light scattering compensation signal for the target block of the color block set is calculated while being calculated.

In an eighth aspect based on the second aspect, the calibrating means has a predetermined size and a predetermined high reflectance used when the image acquiring means acquires the first reference digitized image. And a second reference consisting of a predetermined size and a predetermined low reflectance used when the image acquisition means acquires a second reference digitized image,
The processing means analyzes the digitized images of the first reference and the second reference and generates a predetermined value for the first reference and the second reference.

A ninth invention is the eighth invention, wherein each of the digitized images comprises a plurality of individual pixels,
Each of these pixels has an intensity value that can vary from around 0 to at least 255 and the CCD matrix sensor means obtains a highly reflective, uniform reference surface matrix image and the system: The matrix image is stored in the memory means, and the processing means is
A large number of intensity values of the individual pixels are examined to obtain a compensation coefficient for pixels having intensity values deviated from a uniform intensity value, and the compensation coefficient is a discontinuous amount from the uniform intensity value. Proportionally, further stored in said memory means, for use by said processing means in generating said reflection density values of said at least first color.

A tenth aspect of the invention is suitable for locating an edge position of a winding belt moving during operation in the third aspect of the invention, wherein the processing means winds the CCD matrix sensor means by the carriage means. It is moved to a position near the edge of the strip to obtain a matrix image of a part of the strip, and the image obtaining means is activated in response to the firing of the strobe means, and the obtained matrix image is A matrix of individual pixels each having a low standard deviation of the intensity values below a predetermined limit, each pixel of the image of the unprinted web having a low standard deviation of the intensity values, Each pixel of the image of FIG. 2 has a high standard deviation of the intensity values, and each pixel of the image of the printed web portion is of an intensity value standard which is approximately comparable to the standard deviation of the intensity values of said web support roller. A deviation, the processing means analyzes the matrix image to determine whether there is a pixel with a standard deviation having a low intensity value, and the pixel moves while moving toward one of the edges. The position of the edge of the web is determined by detecting the position where the standard deviation of the intensity is no longer low, and the edge of the web is located, and the processing means has a standard deviation of low intensity in each preceding image. If it is determined that no carriage exists, the carriage means causes the CCD matrix sensor means to cause the image acquisition means to generate one or more consecutive new digitized images along the longitudinal direction of the web. Move it to the acquisition position and analyze the new digitized image pixels approximately along the longitudinal direction of the roll until it is determined that there are low intensity standard deviation pixels. After that, while moving in a direction toward one of the edges, a position where the pixel has no standard deviation with a low intensity value is detected to obtain an edge of the winding strip, thereby locating the edge position of the winding strip. To do.

Broadly speaking, the present invention prints on a web, preferably web, by a web printer of the type having a number of printing stations, each suitable for printing impressions of the respective color. It is intended for a device for determining the reflection density value of each color of the formed ink. Full color printers typically print black in addition to cyan, magenta and yellow. The device embodying the invention is suitable for obtaining the reflection density values for each color in a reliable and accurate manner while the web is moving at high speed during the printing operation.

The apparatus also obtains a digitized image of a moving web using strobe illumination, then examines the intensity of individual pixels in the image and analyzes the digitized image to determine the reflection density value. Suitable to get. The device operates to obtain a digitized image while the press is operating at speeds in excess of 3000 feet per minute, and reflection density values are obtained in real time for each measurement.

This apparatus uses a multi-color CCD matrix sensor, which obtains a matrix image and has a separating means such as a prism for separating or splitting light into red, green and blue components. Each component of is processed in a separate channel. That is, multi-color C
Each matrix image obtained by the CD matrix sensor produces a separate channel for each of the colors red, green and blue, correspondingly measuring the reflection densities of the cyan, magenta and yellow printed ink colors respectively. To do. It should be noted that the sensor may include a different kind of separating means for separating light into red, green and blue components.

It is generally known to those skilled in the art that it is difficult to reliably and accurately measure the reflection density of printed ink using conventional handheld densitometers that have existed for many years. . Such densitometers are prone to drifting measurement results and often must be manually recalibrated. The present invention is suitable for providing accurate and reliable reflection density measurements as a result of auto-calibration and for converting the reflection density measurements into substantially the same readings as those measured by the densitometer. The reading of the densitometer is theoretically 0
Between 3 and 3, a high number represents a minimum reflectance and a low number represents a reflectance of 100%, but the working range is generally between approximately 0.5 and 2.5 with a value of 2.5. Generally represents the darkest dark printable.

The apparatus uses several test print areas which may contain several sets of small solid color blocks of cyan, magenta, yellow and black. These multiple color block sets are each printed across a width of the web at a predetermined position corresponding to an ink zone adjustment control mechanism (often called a key) of the printing press. The test print area may include a plurality of solid color block sets, a plurality of shaded color block sets, a combination of shaded and solid color blocks, and an overprinted multi-solid color block. As is well known in the art, the control mechanism regulates the ink supply in a zone extending across the web. That is, the control mechanism changes the amount of ink that is present during the printing operation and that can ultimately be transferred to the web. Since the control mechanisms are spaced from each other by approximately 1-2 inches, there are approximately 24 zones on a 38 inch wide press. In the device of the present invention, 1-2
A test print area is used at each key position so that the reflection density can be measured every inch.

In the preferred embodiment, each test print area comprises a plurality of color block sets including rectangular color blocks adjacent to each other, each color block set preferably having seven color blocks.
Includes black, cyan, magenta and yellow color blocks in a preferred order. Each color block necessarily results in at least one color block of each color, including black, for the resulting digitized image. All seven color blocks are properly positioned and dimensioned such that they are included in the resulting image. To be decided Digitized image is 760
It preferably consists of pixels x 480 pixels, each pixel having a variable intensity value between 0 and at least 255. The correlation between the analog intensity value and the digital density value can be either linear or non-linear.

However, as part of the calibration capability, the white level is preferably set to an intensity value greater than 200 and less than 255 and the black level is preferably set to an intensity value greater than 0 and less than 63. White level is an official white standard (preferably a reflectance of 9
9%) and the black level is set by obtaining an image of the official black standard (preferably 2% reflectance). The device also compensates for variations in light intensity and color temperature of up to 5%, which occur at the individual firing of the strobe unit. This point is done by measuring the illumination of each firing of the strobe unit and producing a correction value used in such compensation. In addition, the device also compensates for illumination discontinuities in the area of the imaged field of view, which is referred to as optical field discontinuity compensation. This light field discontinuity compensation data is stored in memory and is used during operation to compensate for such illumination non-uniformities.

Further, due to the characteristics of the optical system, some light scattering exists in the device. This causes what is known as the light scattering effect, the intensity of the pixel measured in the analysis area depends on the field of view, i.e. the amount and position of the reflected light from the print itself, and depending on the content of the print, It also causes variations in the intensity readings of the analysis area itself. The device compensates for such light scattering properties. Calibrating and compensating for light scatter, light discontinuities, and strobe illumination variations are important in producing accurate reflection density values during operation.

It should be understood that there are significant sources of paper contamination in the environment of the printing press, and such contamination sources can significantly affect the accuracy of the measurement. In addition, the printing process is not perfect and may result in unwanted spots or spots in the test print area itself.
Various abnormalities can occur. Arrows or other indicia may be printed on the web for reasons unrelated to the test print area, and such indicia are sometimes printed over the test print area to ensure proper alignment of the apparatus of the present invention. This can cause operational problems. For this reason, the apparatus also includes an analysis routine that ensures accurate and reliable performance by correcting pixels that are not within the expected intensity level and then performing an analysis of the measurements to give a reliable reflection density value. .

[0035]

1 is a block diagram of an apparatus embodying the present invention, the apparatus includes a CCD matrix sensor 30 having a lens 32 with a nozzle structure 34. CCD matrix sensor 3
0 is to obtain a matrix image of the web 36, which is wound around the web support roller 38 so as to provide the surface with its printed indicia, and the CCD matrix sensor 30 being wound. A matrix image of each part of the strip can be acquired. A pair of strobe units 40 are CC
The winding band 3 is provided adjacent to the D matrix sensor 30.
The light is directed from both sides of the sensor toward 6,
During operation, the CCD matrix sensor illuminates the area of the web 36 from which the matrix image is obtained. Roll 36
The strobe unit 40 substantially stops the winding member so that a matrix image can be obtained even when is moving at high speed.

The CCD matrix sensor 30, the strobe unit 40, the strobe power supply and trigger module 42, the cable interface and the pixel data amplifier 44 are shown enclosed within a dotted line 46.
Reference numeral 6 represents a carriage structure having an image forming head which laterally moves beyond the width of the scanner roll to obtain a matrix image of the web. Another dotted line 48 represents the portion of the device mounted on the sensor module. An encoder 50 is also connected to the printing press to measure the operating speed of the printing press and to provide a matrix image at the appropriate time to provide a test print area within the field of view of the CCD matrix sensor in the circumferential direction (firing angle). ) Is required to synchronize.

A motor 52 is also attached to the printing machine and drives the carriage back and forth to accurately control the position of the CCD matrix sensor. The motor 52 is a controller 58.
Is preferably a stepper motor driven by a driver 54 which receives a signal on line 56 from The device preferably includes a cabinet containing the components and circuitry shown at the bottom of FIG. The motor controller 58 uses a 16-bit bus 6 via a bus connection 62 similar to other bus connections to other components.
Connected to 0. The other components mentioned above receive the encoder signal from the encoder 50 via the line 66 and the line 6 which also extends to the pixel data memory 70.
Also included is an ignition controller 42 that provides an output signal to the strobe controller 64 via 8 and the pixel data memory 70 receives the digitized image and performs some of the analysis steps for the data in the digitized image.

An input / output (I / O) controller 72 provides control for operation of the pixel data memory 70, CCD matrix sensor 30, strobe controller 64 and motor control portion of the device. Line 74 is I / O controller 72
To a strobe controller 64, which controls the synchronization of strobe firing and causes a matrix image to be acquired by a CCD matrix sensor, the latter image acquisition being functionally performed by data sent via line 76. .
The I / O controller 72 is also connected to an analog / digital (A / D) converter 78 via a line 80, and sensor information from the sensor module 48 via a line 82 and a line 84. It receives data regarding the operation of the pixel data memory 70. There is also a pixel data memory processor 86 for the pixel data memory 70, which is connected to the pixel data memory 70 via line 87. Similarly, the A / D converter 78 for converting the analog matrix image obtained by the CCD matrix sensor into a digitized image by a linear or non-linear method is also connected to the pixel data memory 70 via the line 73.
It is connected to the. The A / D converter 78 may be of a type having a processing capacity of 32 bits. 0 to 25 for three colors
The intensity level of 5 occupies only 24 bits out of 32 bits, so using an additional 2 bits for 4 colors gives a resolution of 10 bits, ie an intensity level of 1024.

The main processing power is implemented by the CPU 88 and Ethernet for networking with multiple devices.
An (Ethernet) network card 90 is also provided.
The sensor module 48 includes a number of sensors, including three end-of-travel (EOT) sensors 91, which provide a signal that the carriage has moved to or near the end of its movement, which signals are provided via line 82. To the I / O control device 72, and further operation stops the motor 52 which may damage the device. The CCD matrix sensor 30 gives an analog signal of the obtained matrix image to the amplifier 44 via a line 93, and a control signal for firing the strobe unit 40 is given via a line 94.

Although most of the operation of the apparatus is performed by the parts shown in the block diagram of FIG. 1, it is understood that the block diagram of FIG. 1 is only a part of the entire equipment installed in the printing press. Should be. The apparatus embodying the present invention is generally suitable for measuring the reflection density and geometry of a test print area in a full-fledged printing press which involves printing on both sides of the web. In addition, this device is similar to the system shown in FIG.
Also suitable for measuring the reflection density of a test print area on each side of one web, the system includes four devices shown at 95 in FIG. 1, a control processor 96, a workstation 98 for each web. And each workstation has a monitor 99 and a keyboard 100. Workstation 98, individual devices 95 and control processor 96
Are connected to each other via an Ethernet network 101,
The control processor 96 may also have a network 102 that links the device to a print shop network.
The control processor 96 is a central message passer (CMP) module 10 that operates to convey messages from each component on the network 101 to another component.
3 inclusive. That is, all messages from one processor to another processor are controlled by the CMP 103. The system also has a hard disk 104, a floppy disk 105 and a modem 106, each connected to a control processor 96. Data regarding the status and operation of the device can be stored in the hard disk 104,
Data can be loaded and unloaded using the floppy disk 105. The modem 106 allows the device to perform diagnostic and maintenance work from a long distance.

It should also be understood that CPU 88 of the apparatus of FIG. 1 is a 486 microprocessor. As will be described later, there are microcode operations performed by the pixel data memory processor 86, which are executed by the CPU 8
It can be carried out in 8. Similarly, although there are functional operations performed on certain components of FIG. 1, this may be performed on another component. As processing speeds continue to increase as computer technology evolves, it is expected that fewer microprocessors shown in FIG. 1 will do the trick.

The present invention substantially includes implementing the concepts described herein, including the specific routines and subroutines described herein for carrying out the claimed invention.
Of course, it is important that the calculations to perform the routine be performed very quickly, but the particular hardware configuration may be quite different from that shown in FIG. For example, some of the subroutines could be done in dedicated hardware.

In accordance with an important aspect of the present invention, the apparatus uses a test print area printed on the web as shown in FIGS. 3, 4 and 5. FIG. 3 shows a trap target block 108 that is created by overprinting each part in the target block by combining inks of magenta, cyan, and yellow colors. FIG. 3 also has block sets 110 and 111 which are combinations of shaded and solid parts. One of the blocksets 110 and 111 preferably has 50% shaded and the other has 75% shaded. The shaded area is made by printing dots of a predetermined size within the shaded area, but it should be understood that the shaded area may not appear as shown in FIG. 3 (b). 4 such blocks per set
It is preferable that one block be present for each color of magenta, cyan and yellow. 4 and 5 do not include a trap target block or a combination of shaded and solid blocks, and are used to measure the reflection density of various color blocks that are part of each set and are used for solid color block set 112.
Is particularly shown. Two of the color block sets are shown in FIG. 3, and one enlarged color block set is shown in FIG. FIG. 5 shows a copy of a portion of a printed page, which is a printed page of a magazine having a page approximately 8 inches wide defined by a left edge 116 and a fold line indicated by dotted line 118. Includes five color block sets near the margin below line 114 representing the bottom. The copy of FIG. 5 is approximately 80% of the normal scale.

Referring to the enlarged view of FIG. 3, a line 114 representing the bottom of the printed matter on the previous page and a left edge 116 are shown.
And a line 120 representing the beginning of the printed material on the next page. The printed matter is schematically represented by diagonal lines and is numbered 122. Each color block set consists of seven color blocks located adjacent to each other, with each color block set 112 located near the control zone of the press, shown in FIG. 3 as 1.565 inches on either side of the center. The area between lines 114 and 120 is color block set 1
12, a gap 124 including, for example, marks for measuring control of cutting lines and alignment control is shown. FIG. 5 shows arrows 26 and short lines 128 used to control cutting, magazine forming, etc. by the printing press.

Referring to the enlarged view of one color block set shown in FIG. 4, this set consists of seven blocks for each color of cyan, magenta, yellow and black. The specific number and type of color blocks are shown in Figure 7.
The number shown in the color block set of FIG. That is, the black color block 130 is located at the center,
The cyan color block 132 is located on the right side and the left end of the black color block 130, the magenta color block 134 is located on the right side of the cyan color block, and the yellow color block 136 is located on the left side and the right end of the black color block. The black color block 130 has a tab 131 in the upper right corner as shown in FIG. 4, and the tab is a different corner for each color block set printed on the web as shown in FIGS. 3 and 5. Is located in. These tabs provide information about which color block is in the location and allow the device to determine if the color block set was skipped when passing through the CCD matrix sensor. It should be understood that smaller or larger size color blocks than illustrated may also be used.

The CCD matrix sensor 30 has approximately 10
It is positioned close enough to the web 36 to obtain a matrix image of size 500/00 inch by 380/1000 inch. In FIG. 4, a rectangle 138 represents the approximate size of the matrix image obtained by the CCD matrix sensor 30 with respect to the size of the color block set 112. This physical size produces a matrix image which, when digitized, is a matrix of individual pixels of 760 pixels x 480 pixels. The device is actually 3 for each of the colors red, blue and green.
Generate one such matrix image. From such a physical size to pixel size ratio, each pixel represents approximately 0.0006 inches. This ratio allows the device to determine the shape and size of the print, including the size of the dots printed on various screens, especially the size of the dots printed on the screen target used to calculate the print contrast and dot gain. It is possible. Also, FIG.
For the color blocks 112 shown in FIG. 1, the size of each block in pixels is approximately 60 pixels wide by 11 long.
It is 2 pixels and one solid color block 136 is shown in FIG. The color block 136 shown in FIG.
The outer boundaries of the top end 140, the bottom end 142, the left end 144,
Includes right edge 146 and tab 131.

The shape of the shaded and solid combination blocks 110 and 111 is shown in FIG. It should be understood that both the solid and shaded portions are adjacent to each other in the circumferential direction of the web, rather than in the transverse direction, ie, the lateral direction of FIG. Used to find print contrast 7
In combination block 110 with 5% shading, an image of block 110 is obtained and the size of the individual dots can be accurately measured as a result of the physical size to pixel size ratio described above. This allows the device to measure dot gain and print contrast from geometric measurements of pixels in known blocks.

Using reflectance, the dot gain can be calculated by the well-known Murray-Davies equation as follows:% Apparent Dot Area = 100 x (1-10- ^{(D (t) -D (p))} ) / (1-1
0- ^{(D (s) -D (p))} -50, where D (s) is the density of the solid part, D (t) is the density of the shaded part, and D (p) is the density of the paper.

For the trap target 108, the apparatus analyzes the image and obtains an apparent trap based on the following equation:% apparent trap = 100 × (Dop−D1) / D2 where Dop is “overprint printing density− Paper Density ", D1
Is "the density of the first applied ink-the density of the paper", and D2 is
"Density of second applied ink-density of paper".

Similarly, the print contrast was analyzed by obtaining a digitized image of a 75% shaded / solid combination block,
It is calculated using the following formula:% print contrast = 100 × (D (s) −D (t))
/ D (s) where D (s) is the major filter density of the solid part, D
(T) is the major filter density of the shaded portion. Depending on the arrangement direction of the shaded and solid combination block 110 in which both the shaded and solid portions are adjacent to each other in the circumferential direction of the winding body, comparison can be made using both the shaded and solid portions on the same circumferential line. Therefore, more accurate print contrast can be measured, and the possibility that the ink application to the shaded portion will change with respect to the ink application to the solid portion due to ink peeling is reduced.

The carriage structure 46 is shown in detail in FIG. 11 and comprises an envelope having an outer wall 148, which holds the CCD matrix sensor 30 and the strobe unit 40 therein. Although FIG. 11 is greatly simplified, the strobe unit 40 is shown as having a collimator lens 150 located near its exit, with the collimator lens 150 centering the strobe light CC.
A point 152 that also coincides with the center line of the D matrix sensor 30.
Send to. That is, the strobe illuminates the image area on the web 36. The light from the strobe unit is CCD
The matrix sensor nozzle 34 exits the outer wall 148 through a transparent window 154 located adjacent to the extending opening. A capacitor 156 is provided adjacent to the strobe unit 40.
And the power supply 158 for the strobe unit is located in the lower right corner as shown. Although the top of the envelope is not shown, it is preferably completely closed to prevent dust particles from entering it and substantially sealed from the outside. In this regard, the only aperture is the one at the end of the cone 34 from which the CCD matrix sensor 30 is air purged so that a matrix image of the web 36 is obtained.

The carriage (structure) 46 is a pair of rails 1 corresponding to a cooperating mounting structure (not shown) on the lower surface thereof.
By moving along 62, it moves laterally with respect to the winding body, that is, in the left-right direction indicated by arrow 160.
The carriage is laterally moved by a belt drive 164. The belt drive 164 is connected to a drive sprocket connected to the motor 52 shown in FIG. Detailed constructions of rails 162 and belts 164 are well known to those skilled in the art, and the particular construction used to move the carriage laterally along the rails or a comparable construction is included in the novel features of the invention. I can't. The carriage 46 moves laterally along the web 36, but may extend beyond the ends 116 of the web and even the edges of the web support roller 38 itself.

The carriage 46 is a schematic enclosure 1
66 may be moved, and the envelope 166 may move to the carriage 4
White reference 16 that can be located near the end of the range of movement of 6
8 and black reference 170. Although not shown in FIG. 11, fiducials 168 and 170 are preferably housed in a dust-free environment, which means that envelope 166 is substantially sealed except when an image of each fiducial is acquired. Means being done. The normal end of the movement does not extend to the envelope 166, only when the reference image is acquired, the carriage can be moved further to the left and activated at an appropriate point to open a substantially closed door or the like to open the reference 168. And 170 are preferably exposed so that their images can be obtained.

In relation to the above, the moving end of motion (EOT)
The sensor causes the carriage 4 to reach the end of the roll supporting roller 38.
Gives a signal indicating that 6 has moved. Further, the ACC moving end sensor indicates the moving end of the envelope 166, and the opposite end of the roller 38 is controlled by the moving end sensor 91. As will be described later, photodiodes 172 are provided adjacent to the collimator lenses 150, respectively, and are located so as to provide a signal proportional to the output of the strobe unit 40. This signal is sent via line 93 to the A / D converter 78 and, after digitizing the analog matrix image, the information used to adjust the intensity values of the pixels which are part of the resulting digitized image. Is part of.

In accordance with an important aspect of the present invention, CCD matrix sensor 30 directs light into three paths or channels,
That is, it is of a type including an internal prism divided into red, green and blue. That is, each obtained matrix image gives a total of three matrix images, one for each of the three colors, and these three matrix images are sent to the A / D converter 78, where there are three separate digitized images. Will be digitized. The intensity values of the individual pixels of the digitized image are lower in the ink color channel of interest. It is desirable to provide a photodiode responsive to the color of each channel to compensate for variations in total intensity and color temperature, in which case an additional sensor similar to sensor 172 shown in FIG. 11 is provided. Such sensors may be manufactured to respond to the colors red, green and blue, or the sensors may be filtered to respond to each color.

The red, green and blue components of the signal represent an addition method which produces the full range of the color spectrum, while the printing of colors on the web is based on the subtraction method and each of the CCD matrix sensors. There is a fixed relationship between the channel and the ink color to be processed. For example, yellow has one of three channels removed, while magenta and cyan have one of the other two channels removed. Black has all three channels removed. Since yellow is blue-free, the complete yellow blue channel yields no blue or 100% red and green. In the case of cyan, there is no red, so the red channel is zero and the green and blue channels are almost 100%. The magenta channel does not contain green and is almost 100% red and blue. Since black does not have all three channels, perfect black produces neither red, green nor blue. Printing yellow over cyan removes the blue and red channels, leaving green. As is well known to those skilled in the art, the subtraction method is used when printing ink, and the addition method is used when red and green are added by light to obtain yellow.

In the present invention, it suffices to look at one channel at a time, and if the signal level decreases, the reflection density is insufficient for the reflectance of the color, so that the decrease indicates the evaluation of the reflection density. High density inks are very dark, which means they reflect less of that color. The reflectance is calculated according to the present invention and is cyan,
To determine the reflection densities of each of the three colors, magenta and yellow, it is only necessary to analyze the three channels individually. The reflection density of black is calculated from the average of one channel or all three channels.

Referring to the operation of the apparatus embodying the present invention, referring to FIG. 12 which is a flowchart outlining the operation of the apparatus, the system is initialized as shown in block 202 via the start block 200, The main loop then begins (block 204) with the switching of multiplexing functions between each case controlling each aspect of the operation of the device (block 206). That is, the routine asks whether to calibrate the CCD matrix sensor (block 208), and if so at startup (block 210). If the CCD matrix sensor has been recently calibrated, the routine queries whether the edge of the web was found (block 212), and if so, executes the routine to find the edge of the web (block 214). ..

There are more than one way to find the edge of the web, but it generally depends on whether there is print on the web. If the web is not printed, the edge of the web can be determined more easily than when it is printed. In either case, once the edge of the web is found, the process returns to the start 204 of the main loop. If it is not necessary to find the edge of the winding, that is, the edge is known, the routine proceeds to Case 3 and determines if data should be obtained (block 216), and if so.
It is determined whether reflection density data or scatter data should be obtained (block 218). If the press operation is new and light scatter data is not available, the device obtains light scatter data (block 220). If light scatter data has already been obtained, the device is set to obtain the reflection density (block 222). As will be described later, when acquiring light scattering data, the device moves the CCD matrix sensor, sequentially acquires a matrix image at each key position across the roll, and digitizes the matrix image for analysis. The content of whiteness in the acquired matrix image is determined. At this time, all pixels in the matrix image are measured relative to the threshold white to determine the amount of light scattering compensation to be done for each particular image. This compensation amount depends on the printed image adjacent to each key.

Once the reflection density data has been obtained, the end of the loop block has been reached (block 224) and the routine queries if the press is down (block 226). If the press is down, the routine is CCD
Ask if it is time to recalibrate the matrix sensor, and if so, recalibrate the CCD matrix sensor (block 230). If it is not time to calibrate, the routine returns to the beginning 204 of the main loop. Generally, if the press has been down for more than 10 minutes, the CCD
It is desirable to recalibrate the matrix sensor. If the press is not stopped, the routine queries whether a motion request has been made (block 232). If a motion request has been made, some work motions can be performed (block 234). A working or normal printing operation involves a view request that allows the operator to request an image of a particular location on the web which may be different from the image obtained for the color block set. Here, the operator of the printing press may also wish to monitor particularly important areas of the impression, such as the brightest areas (highlights). Such an operation generally controls many other data acquisition operations by controlling the CCD matrix sensor to move to a specific position, acquiring the data at an acceptable time, and then returning to normal operation of the device. Can be done at the same time. The operator may also request calibration of the CCD matrix sensor that is determined by the operator and is independent of the CCD matrix sensor calibration routine that occurs during the operation of routines such as those shown in blocks 210 and 230.

Looking at the operation of the device, it can operate in one of several modes including idle, start, sample and maintain. In idle mode, the device is ready to get data, but is not commanded to actually get the data. During the initialization of the printing press operation, the device is prepared for data acquisition, but if, for example, a CCD matrix sensor is calibrated, the light scatter will be seen until a print is present on the web which can be analyzed for light scatter compensation. Can not get the data. The device can determine the edge of the web before the print appears, as well as the width of the web, and the system then waits for the print to appear. When the print appears, the operator is switched to start mode. During the light scatter pass, the CCD matrix sensor slowly moves laterally to obtain light scatter data used to compensate for light scatter. The slow path is needed to obtain the light scatter data because more data is analyzed to determine the light scatter compensation, ie, each pixel of the 760 × 480 pixel matrix. Once several passes have been made to obtain the light scatter data, the data obtained are averaged over those passes to give a reliable light scatter compensation factor used to determine the reflection density.

Light scattering compensation data must be acquired for each of the three channels red, green and blue, and these three compensation factors are generated for each key position across the web. It should be understood. The obtained light scattering compensation coefficient is stored in the memory and used during the printing operation. It should be appreciated that this allows for real-time scatter correction for each acquisition of data. In-line dedicated processors may be required to perform such functions.

Generally, it is necessary to print 5,000 to 25,000 times in order to set a color on the printing press. With the apparatus of the present invention, such settings can be achieved with significantly less prints, i.e. 2,500 prints.

After the start-up mode, the device is switched to the run mode, where there is preferably a minimum number of data passes for every 500 impressions to obtain reflection density data. These reflection density values are stored in memory. In maintenance mode, the device makes several data passes every approximately 500 impressions, stores the data in memory, and is used to generate run report reports for the printing press.

When acquiring the reflection density data, the CCD matrix sensor is moved across the web. The travel speed is synchronized with the web speed of the press and the CCD matrix sensor is rotated for each rotation so that the device can take a digitized image of each color block and calculate the reflection density in less than approximately 70 ms. Move about 1 1/2 inch each. In the preferred embodiment illustrated and described herein, at the set speed of the printing press, the device can obtain a digitized image with each revolution of the printing roller, and digitizes from approximately 12 color keys per second. Images are obtained and analyzed.

As is well known in the printing industry, it is often necessary to keep a sample of printing work, as it may be used in the future, such as when a customer complains about the print quality of a publication. It is not uncommon for a considerable area to store such samples to be set aside in the printing plant. As such, it is uneconomical to use valuable floor space within a printing plant.

According to an important feature of the present invention, the reflection density data obtained in both the sample and maintenance modes is a detailed report of the color density of each color printed approximately every 500 impressions throughout the printing operation. give. Such data can be used to create frequent "snapshot" reports of reflection density, providing a print run history that can be used to satisfy customers regarding print quality.

The apparatus of the present invention substantially prints the reflection density data in memory and can be printed out after work in the form of a report showing the print quality after virtually every 500 impressions. Substantially eliminates the need to keep a copy of the run. The device has 3 lines, where the customer has a 6 digit work number and a 3 digit form
A number, a three-digit run number, a work name, a work description and a publication code can be identified.

The report also gives the printing company a record of the changes made to each key from beginning to end, including the corrections made until the printing press is stable. It also gives useful information. This information can be used as a teaching tool to help printers avoid unnecessary corrections at the beginning of work execution. Typically, another facility within the printing company will provide preset values for each key that have been corrected accordingly until stable press operation is reached. Also, printers typically make initial corrections that are known to be unnecessary because they are too early, and prior to the corrections make initial corrections that mean keying the reflection density that is not stabilized. With the reflectance data obtained from the present invention, many of the premature initial corrections are virtually unnecessary,
It also clearly shows to the printer that each key can be returned to the position or settings that were close to the presets, even after thousands of prints.

In accordance with an important feature of the present invention, referring to FIG. 11, the CCD matrix sensor 30 and the CCD matrix sensor 30 for calibrating the digitized portion of the device.
The carriage 46 is movable to the left side in the figure so that a matrix image of either the white reference 168 or the black reference 170 can be obtained at a predetermined position. Each standard is shown in Figure 1.
As shown in Fig. 0, it has a substantially flat circular shape, and it is a lab in PO Box 70, North Sutton, 03260, New Hampshire, USA.
Spectralon (Spect
ralon) Color standard. These standards are calibrated and measured for 8 degree / hemispherical spectral reflectance using a double beam ratio recording integrating sphere reflectometer. As previously mentioned,
The datums 168 and 170 are contained within a protective envelope 166,
At the time of image acquisition by the CCD matrix sensor 30, there should be no dust particles on the surface of each reference that could significantly affect the intensity readings obtained for each pixel. It is for this reason that the carriage preferably has a mechanism that opens the cover or the like to allow the CCD matrix sensor to obtain the standard 168 and 170 matrix images.

To calibrate the digitized part of the device, C
The CD matrix sensor 30 acquires both black and white reference matrix images, and the matrix images are digitized such that each pixel of the digitized image has an intensity level that falls within a possible range of 0-255. However, the calibration process preferably sets the intensity value of the black standard to approximately 8 and the intensity value of the white standard to approximately 240.
This is for three independent channels, red, green and blue,
It is achieved by treating everything individually.

To begin the calibration process, the carriage 46 is moved to both reference positions so that a matrix image is obtained. Motor 52 (FIG. 1) is moved to the zero position, which is the end of travel limit, and pixel data memory 70 (FIG. 1) is tested to remove bad data values.

The device is equipped with a glass window 1 for both standards and strobes.
Check the spot on 54. This point is a white reference 168 with spots 212, 214 and 216.
It can be understood by reference to FIG. 10 which shows two matrix images of The matrix image shown in FIG. 10 (b) is an exaggerated image obtained after moving the CCD matrix sensor 0.020 to 0.030 inches with respect to the matrix image of FIG. 10 (a). The device logically determines that the spot 216 that has moved to the right in FIG. 10 (b) relative to the position in FIG. 10 (a) is the result of dust located on the window 154 rather than the reference 168 itself. . Many of these spots adversely affect the fidelity of the fiducials, so if such spots are detected, both fiducials and glass window 154 should be cleaned.

However, apart from being able to clean both standards and the glass window, the device of the present invention measures the pixel intensity of each pixel during its analysis and if it is not within a predetermined threshold, It also ignores the pixel in which the spot is located by excluding it. In other words, if the matrix image is black-referenced, the reflectance should be very low and spots with intensity values above 40, for example, are discarded. Similarly, if the matrix image is a white reference, reflection values below approximately 200 are discarded or eliminated when calculating the average of the reference pixel values.

After the spot is located, the device
A matrix image is acquired by moving the D matrix sensor to the black reference, and the matrix image is digitized,
It is set to a predetermined level, which is preferably approximately 8. C
The CD matrix sensor and its associated components continue to acquire digitized images until the level is 8 ± 0.25. If it does not fall within the range, adjustment may be performed until the tolerance is satisfied, and image acquisition may be required about 8 times. The carriage 46 then moves the CCD matrix sensor to capture the matrix image of the white reference 168 and the system is set to have a white level of 240 ± 0.95. Digitized images are continuously acquired for the white reference until the white level is also within this tolerance. Once this is complete, the device repeats the above operation two more times, for a total of three times. After that, the device returns to the black reference and takes 10 digitized images and averages them to give the value used by the device. The same operation is then performed for the white reference and the resulting average value is stored in memory.

The value used by the device consists only of the average of 10 digitized images for each reference taken after the last pass by the routine. The reason for using these values is
Especially set the black level to 8 and the white level to 24
This is because when set to 0, an interaction occurs between the black level and the white level. There is little interaction, so move back and forth between both standards to set each level repeatedly,
It is desirable that the level obtained is accurate.

It should be appreciated that the calibration routine will be performed when the device is powered up and will need to be recalibrated more frequently until the device reaches a stable working temperature. For example, if the printing machine is stopped, the CCD
Recalibrate the matrix sensor to make sure each level is set correctly. Also, the time required to complete the calibration is only approximately 30 seconds to 1 minute.

According to yet another important feature of the present invention, referring to FIG. 11, strobe unit 40 is the center of the light and is also the centerline of CCD matrix sensor 30.
It is clear that it is positioned so that it points to 52. The light passes through each window 154 and reaches an area on the winding body,
Illuminate the web from two directions. Since the intensity of the pixels of the resulting matrix image is a function of the amount of light emitted from the strobe unit, the areas of the resulting matrix image are either uniformly illuminated or the illumination of each area is known so that variations can be compensated. This is very important.

The device analyzes the intensity of the light emitted from the two strobe units to determine what the discontinuity of the light is, and to compensate for the non-uniformity of the light across the matrix image. The device provides this compensation in the area of the entire digitized image obtained from the white reference, preferably about 64x64.
By analyzing the pixels. The device averages the intensities of the pixels in each region and then stores the average value along with the address or location of each region, during compensation,
Either compensation factor is applied to the measured intensity values for the pixels located within each region. Compensation analysis
It only has to be done during initial alignment and, if appropriate, when the optics are adjusted or subsequently changed.

The light discontinuity analysis is performed for each channel of the CCD matrix sensor system, that is, each of the red, green and blue channels has a light discontinuity compensation coefficient for each region of 64 × 64 pixels in the image. Should be understood. The brightest intensity is then set to 1, and all other intensities are calculated for the brightest intensity, typically 0.97, 0.98, 0.99 or 1.0, etc.

According to another important feature of the invention, the accuracy of the reflection density measurement is also influenced by a phenomenon referred to herein as light scattering, which means that the determination of the reflection density depends on the relative position and the resulting matrix. It also means that it may be influenced by the content of the printed matter adjacent to the color blocks of the color block set 112 that are part of the image. As shown in FIGS. 3 and 4, the area 122 above the line 114 may, and in most cases, contains printed matter, and the line 12
The same applies to the area 122 below 0. The resulting matrix image 138 shown in FIG. 4 contains approximately seven color blocks, but at the same time necessarily includes a portion of region 122.

Each color block set 112 has a printed material 122 whose overall brightness changes according to the content of the printed material in the image.
Next to each other, the number of light and dark pixels may change for each key across the width of the web. The effect of light scattering is substantially generated by the higher reflection values, i.e. higher pixel intensities, located in the field of view. In the field of view, on the other hand, such higher intensity pixels have a greater effect the closer they are to the measured pixel. Both of these effects, the amount of high intensity pixels and their proximity to the measured pixel, are asymptotic properties. CCD
The matrix sensor has a focusing lens and a CCD matrix sensor prism that divides the matrix image into red, green and blue channels. It gives one reading when surrounded by black and another reading when surrounded by white. The light is scattered as it travels through the lens, changing the reading of the color block of interest.

The color block set has been analyzed,
It has been found that if the surrounding area 122 (FIG. 4) is all white, it is generally measured as about 94% white. This is because, out of the seven color blocks, only black and the target color block in each channel are determined to be dark. Thus, considering three channels, there are only nine dark blocks in the three digitized images. If region 122 is black, then all white regions are reduced to approximately 80% white.

Depending on the content of the printed matter of the obtained image,
Since the readings obtained from the red, green and blue channels are relatively variable, light scatter compensation must be determined for each of the three channels. This is in part due to the strobe unit's very bright blue light, which makes yellow stand out. The strobe unit is preferably a xenon strobe whose blue light is the predominant component. The output of the xenon strobe is relatively constant,
It may change within a range of ± 5% from one strobe firing to the next strobe firing. Therefore, it is necessary to measure the output of the strobe unit 40 so that the photodiode 1
72 (FIG. 11) is located and the actual output for each strobe is fed back to the pixel data memory 70,
It is used to compensate the intensity values obtained for individual color blocks during the reflection density analysis. The photodiode sums the light output from both strobes. It has been found that the intensity of the light generated during each strobe firing varies by almost 5%, but such variations are random and typically about 1%. Variations of this degree do not result in substantial variations in the intensity values obtained, which is usually 0.75 pixel intensity. However, it is desirable to compensate for such variations as well, by providing three sensors for each strobe unit and placing an appropriate filter in front of each sensor to allow the strobe unit intensity to be measured for each color channel. It is advantageous to more accurately measure the variation in strobe firing for each color.

In order to quantify the phenomenon of light scattering, it is possible to model the effect of light scattering using a printed test pattern and obtain data approximating a light scattering compensation curve as shown in FIG. Compensation of light scattering phenomenon is within the range of 8-240
It can be as high as 5, and the reading will be inaccurate without compensation. This data is stored in the memory for each color. As a result, an asymptotic chart as shown in FIG. 7 is obtained, and as the ratio of white pixels to all pixels changes from 100% to 0, the intensity compensation coefficient decreases from 1 to almost 0.9. The data for determining such a curve may be acquired once for each color, and then used for each device in which the curve is manufactured. However, it is understood that the amount of light scattering compensation is determined for each printing operation, and that one point on the curve for each color for each key is stored in memory and used to compensate the measured light scattering. Should be.

To obtain the light scattering compensation data and the light scattering curve shown in FIG. 7, the instrument analyzes the resulting digitized image of each channel and counts the total number of white pixels in the overall image to determine the total Find the percentage of white in the image. If you have an intensity value greater than half of the full range,
Those pixels are considered white. When the percentages are obtained by averaging the data of the six light scattering passes, the light scattering data is stored in the memory, and the reflection density measured when performing the analysis of the reflection density of each color block with each key during operation. Used to compensate data. The lowest possible percentage of white pixels is 80%, so the area of the curve actually used is the left part of the curve shown in FIG.

The apparatus first calculates the start and end positions of the CCD matrix sensor pass across the roll. The method by which the device locates both edges of the web and calculates the width of the web is described below. Once the start and end positions have been calculated, the device reads the speed of the printing press and calculates the speed required to obtain an image of the color block set at each key position. The apparatus also calculates the acceleration time, which is the time required for the carriage 46 to start from a stop position corresponding to the left side of the actual winding strip edge 116 shown in FIG. The speed of the printing press is obtained from the encoder 50. If the acceleration time is acceptable, the routine sets the motor speed, strobe controller 64 and pixel data memory 70 to establish the priority of operation. If the starting time is not acceptable, the motor control device 5
8 will change the position of the carriage 46 so that by the time the first key is reached, it will be accelerated to reach the proper pass speed. When the position is changed, the speed of the printing press is read again and the pass speed and acceleration time are recalculated. After the strobe control motor speed and pixel data memory are set, the routine uses a fast delay timer to wait for the next strobe firing opportunity, and after waiting for the computation time, starts moving the motor 52 to a strobe interrupt. Enable.

With respect to strobe firing timing, it should be understood that each revolution of the encoder 50 corresponds to 3600 counts. The device is, for example, trying to fire a strobe with a particular encoder count of 2000, which is 8 milliseconds, but depending on the rotational speed of the encoder, different counts may be needed to fire the strobe at the appropriate time. It is known to be necessary or not. To determine which count should be used, the device counts up for a quarter of a revolution using a fixed speed clock to keep track of how long it takes and how many counts to equal 8 milliseconds. Ask if you need. If this is required, the CCD matrix sensor is reset, the countdown is performed, and the strobe is fired at 200 counts.

According to yet another important feature of the invention, the two edges of the actual winding during operation are first located,
It is important to check the width of the web. This is done at the beginning of the work run of the printing press and does not have to be done again during that run. Knowing the width is important for determining how many keys are used by the printing unit across the web with control of the reflection density. Also, after the width has been calculated, at least one edge of the web is monitored so that the device can determine if the web has moved laterally with respect to the rollers 38 during operation of the printing press. That is also important.

Further, when the operation of the printing press is in the maintenance mode or the execution mode, it is possible to perform the reflection density pass every approximately 500 times of printing and leave the apparatus in the idle state while the reflection density pass is not performed. Especially important. However, even in the waiting state, the apparatus traces the edge of the winding body so that the position of the color block set can be accurately calculated, and the position of the color block set can be located when the reflection density pass is performed.

If there is a printed matter on the edge of the web, it may be troublesome to find the edge position of the web. It is often difficult to distinguish the printed matter on the web from the surface of the roller 38 when the printed matter is printed all the way to the very edge of the web. In practice, while the roller is generally made of high reflectance steel, ink is often present on the roller surface adjacent to the roll, which makes it difficult to distinguish the roll from the roller. Basically, the edge of the winding strip is obtained by acquiring an image of the known position of the winding strip, then analyzing the pixels while moving in a stepwise manner toward the edge, and locating the edge position. The analysis in this case is generally based on the fact that the white paper to which the web is has a strength value known to be between 240 and approximately 128. Rollers typically produce maximum intensity values of 255 without ink on their surface. Therefore, if the strength exceeds 240, it is understood that the roller surface is analyzed, and the strength is 240
Between 128 and 128, it is the winding itself that is being analyzed. If the strength is lower than 128, it is determined that it is a print on the web or ink on the roller.

The device takes advantage of the fact that all printing machines have a printing cylinder on which the plate is mounted.
Referring to FIG. 8, which is an end view of the printing cylinder 370,
The printing cylinder 370 has a gap 372 used to mount the plate thereon, the plate extending from one side of the gap 372 along the circumference of the printing cylinder 370 to the opposite side of the mounting gap. The importance of the gap 372 lies in providing a printing gap on the web because it is present on every impression cylinder and no print is printed on the part of the web which overlaps the gap 372. The portion of the winding strip corresponding to the region based on the gap 372 is between the lines 376 and 368 as shown in FIG.

Gap 372 is becoming smaller and smaller at the current state of the art in printing presses, with some printing presses now having a gap of only 0.040 inches, compared to the full gap of 0.25 inches in many conventional printing presses. Inches. The printing plate prints two pages with a space indicated by 124 between each printing, and the color block set is printed in the space. The state of the art in printing presses not only reduces the size of the gap 372, but also its space or gap 1 shown in FIGS.
24 has also been reduced, some as low as 0.100 inches. In this case, the color block height needs to be only 0.09375 inches, which is almost 1
It is 12 pixels. The height of the color block seems to be even smaller.

This apparatus locates the edge position of the winding band. At start-up, it is important for the device to know its current position, so that the motor can be moved first to the leftmost stop position and then to the correct position to start the analysis.

A common method performed by the apparatus is to locate the color block, which allows verification of paper size and determination of color block set position. This is done to ensure that the device is acquiring an image of each color block set. If you find the color block set on both ends,
Use their presence to check the width of the paper. If the press is running in maintenance mode,
The device continuously scans for one of the color block sets at the edge of the paper to see if the web is moving horizontally or circumferentially.
In other words, it tracks the winding body.

The device operates in three modes. In the start-up mode, which is operated for the first time, the device locates the color block set and determines the width of the paper. If this is done successfully, check to see if keys on the edge of the web are available. To do this,
Occasionally, the mark may be printed over the color block, or the color block set at the end may be put on or off half of the band and may not be usable. That is, the routine checks the outermost keys to see if they are valid, and if the outermost keys are not valid, it moves to the next key and uses the color block set for that key to wind the scroll. Track the body. Thus, in start-up mode, the device locates the color block set, finds the width of the paper, finds a valid key,
After this is completed, the edge key is analyzed during operation. And if the edge key is lost, jump back to the search loop looking for it. If for some reason the edge key is not found, the device repeats the above process from the beginning and searches for the first set of color blocks.

According to still another important feature of the present invention, even when printing is performed, that is, when there is a printed matter on the web and the position of any color block set cannot be determined. The device is configured to find the edge of the web. Basically, the apparatus determines the edge position of the winding body by locating the gap between the two lines 376 and 378 (FIG. 9) on the winding body and using that gap area to find the edge of the winding body. To act like. This is because it is known that there is no printed matter on the web at the gap position.

The device acquires an image and analyzes the resulting image to read two vertical lines in the acquired image as shown at 470 and 472 in FIG. That is, the task of this process is to take an image and perform the analysis vertically until the analysis moving along both lines 470 and 472 agrees, ie the gap between the two lines 376 and 378 is reached. Is to make sure that it actually contains the gap. Then, at this point, the routine allows movement toward the edge based on points 394 and 396.

This device acquires actual reflection density data during operation and accurately obtains the reflection density value. This device also
Effectively locate the color block of the color block set for each key and calibrate the digitizing part of the device,
Compensates for strobe unit intensity, light discontinuities over the area of the image, and light scattering.

When the device starts to analyze the reflection density, it first gives the average sum, the number of pixels, the color being analyzed, the position on the screen, and the calculated row average of the reflection density. The device then calculates the required light discontinuity compensation and light scattering compensation for the particular pixel of interest, determines both the white and black levels of the color being analyzed, and calculates the compensated average. The device then calculates the reflection density from the compensated average and both the white and black levels of the color being analyzed. The device then calculates the key number, stores the reflection density value according to the key number and color, and sets a good reflection density state. The device then asks if all the data has been analyzed, else it returns to the start of the analysis. If all the data have been analyzed, the advance direction is reversed by the number of paths (channels).

The data obtained from the analysis of the reflection density is the color being analyzed, the x and y coordinate values on the image, the height and width of the area being analyzed, the sum of all the pixels in the area,
And the number of pixels added.

Each color block in the color block set is located as shown in FIGS. The device is set to acquire an image at the first key position. Once the image is obtained, a search of the color block set is called to find all color blocks 1 present in the image.
Locate 30-136. For each color block found, the device reads the data in the block.

As shown in FIG. 6, the color block is approximately 60 pixels by 112 pixels in size, and the analysis area is a rectangle 651 that is preferably located in the middle of the color block and preferably 40 x 70 pixels in size. . The device then determines if the read was successful, and if so, queries if there are four or more blocks and the average vertical block position is calculated. It is then determined if the block is larger than 50 pixels from the center of the color block and, if so, the vertical position of the CCD matrix sensor is adjusted. The device then proceeds to the next block,
Queries if four or more blocks were found. If four or more blocks are found, the system checks to see if the correct color block has been analyzed. This point
It does this by verifying the correct order of the blocks, determining if the spacing is valid, making sure that every fourth block is the same color, and that the black blocks have tabs. . Blocks that are not properly spaced are removed by the device. The device then determines if the correct color block was found and, if not found, adjusts the vertical position of the CCD matrix sensor.

According to another feature of the invention, the apparatus of the invention is equivalent to the readings obtained with a handheld densitometer for printing machine operators who have used conventional handheld densitometers for many years. It is convenient because you can use the densitometer readings obtained by. To get an accurate analysis value of the reflection density,
Strictly speaking, a transformation is needed as given by: Reflection Density = −Log ₁₀ [(value −B _level ) / (W _level −
B _level )] where B _level is equal to the pixel value without reflection,
W _level is equal to the pixel value for 100% reflection.
Since the white level is preferably calibrated in the range of 200-240 and the black level is preferably calibrated in the range of 0-63, if it respectively does not reflect at all (white) or if it reflects completely. It is the standard for (black). These values can be set more finely for the white level 242 and the black level 4,
In this case, the above equation generally becomes: Reflection Density = −Log ₁₀ [(value−4) / 238] This device provides a measurement that is roughly comparable to that obtained with an accurately calibrated handheld densitometer. The value is generated with high reliability.

In accordance with another feature of the present invention, referring to FIG. 11, nozzles 34 may be used to remove dust or dust that interferes with the lenses of CCD matrix sensor 30 to reduce the number of pixels included in the various analyzes described above. It is designed to prevent other particles from getting inside the dust. Nozzle 3
4 has a pair of ports 1200 to which air hoses 1202 are respectively attached, these air hoses being connected to a positive air pressure source so that air is guided into the nozzle 34. The nozzle 34 has an inner annular chamber 1204 with an inner wall 1206, which allows air to pass through the nozzle 3.
4 has a number of openings 1208 pointing into the interior.
The air is also directed towards the main center opening, opening 1
208 is at a slight angle to the centerline of the CCD matrix sensor to create the swirling effect. The air stream thus formed limits the entry of particles that may reach the lens into the nozzle.

Although various embodiments of the present invention have been illustrated and described above, various alternatives, substitutes and equivalents other than those described above can also be used, and the present invention also covers the claims and the equivalents of the claims. It should be understood that it is limited only by the content.

Various features of the invention are set forth in the following claims.

[0108]

According to the above description, cyan, magenta,
It should be understood that a device has been described which requires the reflectance densities of each of the yellow and black colors to be determined in a highly accurate and reliable manner. Accurate and reliable operation is due to sophisticated calibration and compensation techniques, as well as their implementation in the digital domain. This device is 300
Real-time reflection density measurements can be made while the press is running at speeds above 0 feet and can be used to control individual keys on the press to give the desired ink reflection density during operation. Control signals can be generated.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus embodying the present invention that monitors what is printed by a webbing printer on one side of a webbing.

FIG. 2 is a block diagram of an apparatus embodying the present invention that monitors what is printed on each side of two webs.

FIG. 3 is an enlarged plan view of a portion of a web with printed material in addition to the two solid color block sets of the test print area used by the apparatus of the present invention. Figure 3A
FIG. 4 is a diagram showing an enlarged part of the shaded and solid combination color block shown in FIG. 3.

FIG. 4 is a diagram showing one solid color block set in which a test print area is enlarged, together with outline lines of a schematic size of a matrix image obtained by a CCD matrix sensor.

FIG. 5 is a print showing a portion of one page of a magazine, which has been reduced by approximately 20% and has a width of approximately 8 inches, and which has five solid color block sets of a test print area printed in the outer area of the printed page. FIG.

FIG. 6 is a diagram showing one color block together with two spots.

FIG. 7 is a diagram showing a graph of a typical light scattering compensation approximation curve.

FIG. 8 is a simplified schematic end view of a printing roller of a printing machine.

FIG. 9 is a simplified representative side view of a portion of a web on a roller.

FIG. 10 is a side view of a high reflectance reference used to calibrate the digitizing portion of the apparatus of the present invention and another side view of a high reflectance reference used to calibrate the digitizing portion of the apparatus of the present invention.

FIG. 11 is a partially removed and partially cross-sectional plan view showing the image forming head, showing the state in which the head is at a position for acquiring a matrix image of a part of the winding member.

FIG. 12 is a flowchart showing the operation of the main image control program.

[Explanation of symbols]

30 CCD Matrix Sensor 36 Roll (rolling paper) 38 Printing Roller (roll Support Roller) 40 Strobe Means (Unit) 46 Carriage (Means) 70 Pixel Data Memory 86 Pixel Data Memory Processor 88 CPU 95 Reflection Density Measuring Device 108 Overlay Printed solid block (trap target block) 110, 111 Shading and solid combination block set 112 Solid block set 116 Wedge edge 122 Printed material 138 Matrix image 150 Collimator lens 160, 170 First, second (white, black) Standard

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Claims (10)

[Claims] 1. An adjustable ink zone control mechanism for controlling the amount of first color ink transferable to the web at positions spaced apart from one another across the width of the web printer during printing operations. A roll band printer having a printing roller for transferring ink to the roll, which has a non-printing region extending in the lateral direction of the roll with the plate attached to the print roller. , Using the color block set having at least the first color, wherein the web printer is arranged substantially at each of the positions spaced apart from each other on the web while the web printer is operating. A dynamic reflection density measurement control system for a web printing press for measuring the reflection density of at least a first color printed on a moving web comprising a plurality of pixels having intensity values within a predetermined range. Digit of the specified size Image acquisition means for acquiring a digitized image, a memory means for storing the digitized image, a strobe means for illuminating at least a predetermined area of the winding member at the time of ignition, and high and low light reflection of the digitized image. Calibration means for calibrating the image acquisition means by providing a predetermined value for the rate level, and measuring the presence and intensity of the printed matter located in the acquired digitized image of at least a portion of one of the color block sets. And a compensating means for generating a light scattering compensation signal for compensating for the presence of the printed matter affecting at least the measured reflection density of the first color; and a uniform reference surface stored in the memory means. Analyzing the acquired digitized image and the intensity of illumination for a plurality of positions throughout the digitized image acquired during the firing of the strobe means by analysis of the digitized image And processing means for generating a light discontinuity compensation signal for compensating for the non-uniform illumination between the plurality of positions, the processing means analyzing the digitized image including at least the first color. To produce a reflection density value of the digitized image, the reflection density value being modified by the light scattering compensation signal and the light discontinuity compensation signal. Density measurement control system. 2. The image acquisition means comprises charge coupled device (CCD) matrix sensor means suitable for acquiring the digitized image, the CCD matrix sensor means comprising a lens and a lens passing through the lens. Separating means for separating the light into three paths respectively having red, green and blue light, wherein the CCD matrix sensor means has three channels corresponding to the three paths separated by the separating means. 2. The dynamic reflection density measurement control system for a webbing printer according to claim 1, wherein each of the channels outputs an image matrix of a corresponding color. 3. The CCD matrix sensor means and the strobe means are mounted to obtain a digitized image of a desired region of the roll, and the CCD matrix sensor means and the strobe means are attached to the roll. A dynamic reflection density measurement control system for a webbing press as claimed in claim 2, further comprising carriage means for moving across the width. 4. The processing means further comprises means for measuring the intensity and color of illumination generated by the strobe means at the time of ignition and generating a strobe intensity signal indicating the measured intensity and color. 3. The dynamic reflection density for a webbing printing machine according to claim 2, wherein the strobe intensity signal is used to generate the reflection density that compensates for variations in intensity and color during strobe firing. Measurement control system. 5. The winding band according to claim 1, wherein the color block set includes a solid color block, a shaded block, a block obtained by combining solid and shaded areas, and an overprinted solid block. Dynamic reflection density measurement control system for body printing machines. 6. The memory means is a substantially asymptotic curve when plotted together.
FIG. 6 shows the relationship between the high reflection level of a pixel in a digitized image and the distance from a color block of interest in the digitized image for a light scatter compensation signal, and these relationships are plotted together to yield a substantially asymptotic curve. A dynamic reflection density measurement control system for a webbing printer according to claim 1, characterized in that it has the following light scattering compensation data. 7. The processing means analyzes substantially all pixels of a digitized image of the color block set to determine at least one light scatter compensation signal for the color block set,
2. The dynamic reflection density measurement control system for a webbing printing machine according to claim 1, wherein the light-scattering compensation signal for the target block of the color block set is calculated. 8. The calibration means comprises: a first reference having a predetermined size and a predetermined high reflectance used when the image acquisition means acquires a digitized image of the first reference; and the image. The acquisition means has a second reference having a predetermined size and a predetermined low reflectance used when acquiring the digitized image of the second reference, and the processing means has the first reference and the second reference. A dynamic reflection density measurement for a web printing press according to claim 2, characterized in that the digitized image of the second reference is analyzed to generate predetermined values for the first reference and the second reference. Control system. 9. Each of said digitized images comprises a plurality of individual pixels, each of said pixels having a variable intensity value over a range from near 0 to at least 255, said CCD matrix sensor means being high. A matrix image of a surface of uniform reference with reflectivity is obtained, the system stores the matrix image in the memory means, and the processing means examines a number of intensity values of the individual pixels. Determining a compensation factor for pixels having intensity values that deviate from the uniform intensity value, the compensation factor being proportional to the amount of discontinuity from the uniform intensity value and further stored in the memory means, 9. Dynamic reflection for a web printer according to claim 8, characterized in that it is used by the processing means in generating the reflection density value of the at least first color. Degree measurement control system. 10. It is suitable for locating an edge position of a winding band moving during operation, wherein said processing means is said CC means by said carriage means.
The D-matrix sensor means is moved to a position close to the edge of the winding strip so as to obtain a matrix image of a part of the winding strip, and the image obtaining means is activated in response to the firing of the strobe means, and the acquisition The printed matrix image consists of a matrix of individual pixels each having a low standard deviation of intensity values below a predetermined limit, each pixel of the image of the unprinted web having a low standard deviation of intensity values. , Each pixel of the image of the roll support roller has a high standard deviation of the intensity value, and each pixel of the image of the printed roll portion is approximately comparable to the standard deviation of the intensity value of said roll support roller. The standard deviation of the intensity value, the processing means analyzes the matrix image to determine whether there is a pixel with a standard deviation having a low intensity value, and the processing means moves toward one of the edges. Don't move Locating the edge of the strip by detecting the position where the pixel has no low standard deviation of the intensity value and determining the edge of the strip, the processing means comprising: If it is determined that a low standard deviation does not exist, the carriage means directs the CCD matrix sensor means to the image acquisition means by one or more new consecutive digital signals along the longitudinal direction of the web. Move to the position where the image is acquired and analyze the pixels of the new digitized image approximately along the longitudinal direction of the roll until it is determined that there are low standard deviation pixels with low intensity values, then the edges The edge position of the winding strip is determined by detecting the position where the pixel has no standard deviation with a low intensity value while moving in the direction toward one side, and obtaining the edge of the winding strip. A dynamic reflection density measurement control system for a webbing printer according to claim 3, characterized in that the position is determined.