JP2006168287A - Online print quality inspection device - Google Patents

Abstract

An object of the present invention is to convert a reflected light amount signal from a light receiving element attached to a printing press into data such as color values used for printing quality control, and online with image quality data such as color values as a reference prepared in advance. We propose a method and a device that enable instant comparison and confirmation.
A quality inspection apparatus for a printed matter being printed by a printing press, comprising a light emitting element and a light receiving element installed in the printing press, wherein the print image information of the printed matter is separated into three primary colors and read. Obtained by an input means, a conversion means for converting the three primary colors and the like into color values, a second input means for inputting the color values of the print image prepared in advance in consideration of the print state, and the conversion means The value obtained and the value given from the second input means are compared, and the analysis means for converting the information into information necessary for print quality control, and the result obtained by the analysis means in real time during operation of the printing press And an on-line print quality inspection apparatus.
[Selection] Figure 1

Description

  The present invention relates to a method and apparatus for inspecting printed matter on-line for checking the quality of printed matter printed by a printing press.

Conventional quality inspections of printed matter include on-line inspection for smudges, irregularities, creases, tears, etc., and on-line inspection for density, dot gain, and color tone after printing is completed or after stopping. It was broken.
The former uses a reading device such as a CCD camera installed on a printing press such as a rotary press to continuously read the printed matter and detect and display printing defects such as dirt, irregularity, folding, and tearing online. . However, with this method, it has been impossible to inspect and manage the quality such as printing density and color value.

On the other hand, the latter removes the printed matter printed by the printing press, measures the data used for printing management such as density, color value, dot gain, etc. with a commercially available densitometer or colorimeter, and manages the quality. In order to check the quality, the printing operator stopped the printing machine each time, measured the machine, adjusted the machine accordingly, and managed the printing quality offline.
In addition, the reflected light amount signal from the signal detection device attached to the printing press can be converted into data such as density, color value, dot gain, etc. used for printing management, and print quality can be checked instantly online. There was also a method and apparatus invention.

However, with this method, quality control of the printed matter printed on the printing press can be performed, but it is compared with image quality data such as color values that are assumed in advance, and the print quality is confirmed, and machine adjustment is performed. It was difficult to do.
JP-A-7-323526 JP-A-7-323525 Japanese Patent Application No. 2004-173812 Japanese Patent Application No. 2004-175225

  In view of the above, the present invention converts a reflected light amount signal from a signal detection device attached to a printing press into data such as a color value used for printing management, and provides image quality data as a reference prepared in advance. It is intended to propose a method and an apparatus that can be compared and confirmed instantaneously online.

The present invention is an on-line print quality inspection apparatus for inspecting the quality of printed matter being printed on a printing press,
A first input means comprising a light-emitting element and a light-receiving element installed in a printing press, wherein the print image information of a printed matter is separated into three primary colors, or three primary colors and an infrared color and read;
Conversion means for converting the three primary colors, or the three primary colors and the infrared color into color values;
A second input means for inputting a color value for the print image prepared in advance in consideration of the print state;
An analysis unit that compares the value obtained by the conversion unit with the value input from the second input unit and converts the value into information necessary for print quality control;
Display means for displaying the result obtained by the analyzing means in real time during operation of the printing press;
The present invention relates to an on-line print quality inspection apparatus.
Further, according to the present invention, the first input means irradiates the print image with light of three primary colors or three primary colors and infrared light from three or four types of light emitting elements when the printing press is operated, By continuously detecting the print image using the light receiving element that reacts to the light provided in the input means and averaging the detected signals, the signals of the three primary colors or the three primary colors and the infrared color of the print image are obtained. It is related with the said online printing quality inspection apparatus characterized by the above-mentioned.

  Further, according to the present invention, the conversion means uses XYZ or CIEL * a * b according to a polynomial approximation formula that differs for each color from the signals of the three primary colors or the three primary colors and the infrared color of the print image obtained from the first input means. The present invention relates to the above-mentioned online print quality inspection apparatus for converting color values to *.

  Further, according to the present invention, the second input means uses the known color management system to reproduce XYZ or CIEL * a * b * from the RGB value or CMYK value of the print image to be targeted. The present invention relates to the above-described online print quality inspection apparatus which converts and calculates the color value.

In the present invention, the analysis unit compares the color value obtained by the conversion unit with the color value obtained by the second input unit, converts the color value to a value necessary for print quality management, and is set in advance. The present invention relates to the on-line print quality inspection apparatus that analyzes in real time whether or not the print quality control standard value is met.

  According to the present invention, in view of the above points, the present invention is prepared in advance by converting a reflected light amount signal from a light receiving element attached to a printing press into data such as a color value used for printing quality control. There is an effect that the image quality data such as a reference color value can be instantaneously compared and confirmed online.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing an example of the configuration of the apparatus of the present invention. This device has a first input unit installed on the printing machine for capturing images, an inspection unit for comparing and analyzing the input image with a reference prepared in advance, and inspecting print quality, and a display for displaying inspection results in real time. Including parts.

  The first input unit as the first input means includes a light emitting element and a light receiving element. As the light emitting element, for example, three colors of light of red, green, and blue, or four colors of red, green, blue, and infrared are used. It is possible to use a light emitting diode such as an LED that can irradiate the light. The three or four colors are not particularly limited as long as data conversion described later is possible, but the RGB three primary colors are preferable in terms of convenience and the like, and the RGB three primary colors will be described below as representative examples.

  The light emitting element irradiates a printed material during operation of the printing press. The light emitting element is not particularly limited as long as it can monitor the printed matter, and may be inside or outside the printing press. Irradiation may be direct irradiation or via a mirror or a color filter. Irradiated and reflected light is detected by the light receiving element. The positional relationship among the light emitting element, the printed material, and the light receiving element is not particularly limited as long as the printed image can be detected. For example, it arrange | positions so that it may reflect in the running direction of the base material printed. As the light receiving element, a semiconductor element that reacts to light, such as a CCD, a CMOS, or a photodiode, can be used. Further, it can also be used when a light-emitting element or a light-receiving element that is more effective in the future is developed.

  The light-emitting element may be one light-emitting element capable of emitting two or more colors by filter replacement or the like, or may be one light-emitting element for one color. The light receiving element may be capable of receiving two or more colors by exchanging filters or the like, or may be one light receiving element for one color. There is no particular limitation on the order of the colors to be irradiated, and light of several colors may be simultaneously irradiated as long as the reading can be performed independently on the apparatus.

  There may be one first input unit or two or more first input units in the online print quality inspection apparatus. For example, the first input unit may be arranged at equal intervals in the horizontal direction of the paper to be printed.

  The inspection unit which is a main part of the apparatus includes an instruction unit, a conversion unit which is a conversion unit, a second input unit which is a second input unit, an analysis unit which is an analysis unit, and a storage unit. The inspection unit may be a normal personal computer to which an instruction unit such as a keyboard is connected. From the instructing unit, a start signal for data input to the first input unit and the second input unit, the start of inspection to the conversion unit, the analysis unit, and the storage unit, setting of various inspection conditions, and instructions are performed. Also, the inspection result output to the display unit may be made from the instruction unit.

The conversion unit reads a predetermined number of times of print image data consisting of three primary colors RGB or four colors obtained by adding an infrared color to the three primary colors sequentially sent from the first input unit in accordance with the operation of the printing press. Is converted into color values (XYZ, CIEL * a * b *, etc.) for printing CMYK (cyan, magenta, yellow, black) using a polynomial approximation method.
For example, using (Equation 1)

  The characteristics of the light receiving element of the input device are set in advance as variables a, a ′, a ″, b, b ′, b ″, c, c ′, c ″, and the input RGB is output as the output color value signal L * at the time of conversion. In this embodiment, a three-variable first-order conversion formula is shown, but three-variable second-order or third-order conversion may be used.

  The second input unit inputs a color value that serves as a reference for an image to be printed. The reference color value is prepared by calculation in consideration of the printing characteristics and printing conditions of the printing machine to which this apparatus is connected. Usually, the RGB value or CMYK value of the print image to be targeted is commercially available. XYZ or CIEL * a * b color values converted by a known color management system can be used. In addition, as a reference color value, a reference value in standard printing, a value of a different printing machine, or a value at a different time of the same printing machine may be used.

  The analysis unit compares and analyzes both from the color values obtained by the conversion means and the second input unit, and is necessary for print quality control such as color unevenness, variation, and stability of the printed matter using color difference etc. It is possible to convert it into various information. The converted information necessary for quality control is analyzed in real time as to whether it conforms to a preset print quality control reference value, and is used as an inspection result.

  The inspection unit preferably includes a storage unit. The storage unit stores the analysis result as digital data.

  Further, the display unit, which is a display unit, displays the inspection results sequentially sent from the inspection unit during operation of the printing press in real time, and a monitor or a printer can be used.

FIG. 2 is a flowchart showing the processing of the online print quality inspection apparatus.
First, the reference color value input by the second input unit and the print quality management reference value for managing the color value are taken into the inspection unit. These values are input using, for example, a network, various storage media, or the instruction unit. Next, printing of the image is started. By sending an analysis start instruction from the inspection unit to the first input unit during operation of the printing press, the image input of the first input unit starts.

Next, the RGB three primary colors of the captured image that are sequentially sent in accordance with the operation of the printing machine, or the print image data composed of four colors obtained by adding the infrared color to the three primary colors is averaged according to the number of times of reading that is specified in advance. Convert to color values (XYZ, CIEL * a * b *, etc.) for printing CMYK (cyan, magenta, yellow, black) by an approximation method.
Then, the conversion-created color value and the reference color value input by the second input unit are transmitted to the analysis unit.

  The analysis unit derives a color difference or the like from the two image color values, and displays a result of comparison analysis such as a deviation from the reference color value on a display unit such as a monitor or a printer. At this time, a warning is displayed together with a result greatly deviating from the print quality control reference value.

Finally, when the analysis result is stored, it can be stored in the storage unit in a reusable form by a storage instruction.
In addition, if there is a problem with the print quality due to the analysis result, send the analysis result as a signal to the inking device that adjusts the ink supply amount provided in the printing machine, and adjust the ink supply amount to the optimal amount. Is also possible.

Example of device configuration Flow chart showing print inspection process

Claims (5)

An online print quality inspection device for inspecting the quality of printed matter being printed on a printing press,
A first input means comprising a light-emitting element and a light-receiving element installed in a printing press, wherein the print image information of a printed matter is separated into three primary colors, or three primary colors and an infrared color and read;
Conversion means for converting the three primary colors, or the three primary colors and the infrared color into color values;
A second input means for inputting a color value for the print image prepared in advance in consideration of the print state;
An analysis unit that compares the value obtained by the conversion unit with the value input from the second input unit and converts the value into information necessary for print quality control;
Display means for displaying the result obtained by the analyzing means in real time during operation of the printing press;
An on-line print quality inspection apparatus characterized by comprising: The first input means can irradiate the printed image with light of three primary colors or three primary colors and infrared light from three or four types of light emitting elements when the printing press is operating, and each input light quantity can be provided in the input means. A print image is continuously detected using a light receiving element that reacts to the light, and the detected signals are averaged to obtain signals of the three primary colors or the three primary colors and the infrared color of the print image. The on-line print quality inspection apparatus according to claim 1. The conversion means converts the three primary colors or the three primary colors and infrared signals of the print image obtained from the first input means into color values of XYZ or CIEL * a * b * using polynomial approximation formulas that differ for each color. The on-line print quality inspection apparatus according to claim 1 or 2. The second input means converts the RGB value or CMYK value of the print image to be targeted into XYZ or CIEL * a * b * color values that can be reproduced on a printing press using a known color management system. The on-line print quality inspection apparatus according to any one of claims 1 to 3. The analysis unit compares the color value obtained by the conversion unit with the color value obtained by the second input unit, converts the color value to a value necessary for print quality management, and sets it to a preset print quality management reference value. The on-line print quality inspection apparatus according to any one of claims 1 to 4, wherein the on-line print quality inspection apparatus analyzes in real time whether or not it conforms.

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