KR100420997B1 - Image forming apparatus and method of calculating density of image formed on the photosensitive belt thereof - Google Patents

Abstract

Disclosed are a printer and a method for measuring the density of an image formed on a photosensitive medium thereof. The printing machine includes a photosensitive medium, a light scanning device for irradiating light to the photosensitive medium, a developing device for developing an electrostatic latent image formed by the light scanning device on the photosensitive medium, and a developing material; A light detector configured to detect light incident from the test image and output the color component included in the light received from the test image into a main color component and a sub color component, and a subtracted from the main color component output from the light detector. And a density calculating section for obtaining the density value of the image corresponding to the result obtained by subtracting the color component from the reference table and outputting the density value to the controller for controlling the overall printing machine. According to the printing method and the density measurement method of the image displayed on the photosensitive medium, the image density reproducibility of the printing press can be precisely measured, and can be used to determine the printing capacity change of the printing press.

Description

Image forming apparatus and method of calculating density of image formed on the photosensitive belt

The present invention relates to a printing press and a method for measuring image density formed on the photosensitive medium, and more particularly, to a printer for measuring the density of an image by analyzing color components of light incident from an image formed on the photosensitive medium and an image formed on the photosensitive medium. It relates to a concentration measurement method.

In general, a printing machine includes a photosensitive medium, a photoconductor for scanning an image on a photosensitive medium to form an electrostatic latent image, a developer for developing an electrostatic latent image formed on the photosensitive medium with a developing material, and a transfer for transferring a toner image formed on the photosensitive medium to paper. With a device.

Such a printer may have a poor density reproducibility of an image corresponding to the received print data due to aging of each device, for example, a photosensitive medium, a light scanning device, or a change in developing conditions.

Conventionally, since a device capable of measuring image reproducibility attenuation of a printing press is not provided, there is a disadvantage in that the performance degradation of the printing press cannot be properly determined.

The present invention has been made to improve the above problems, and provides a printing press and an image density measuring method formed on the photosensitive medium which can determine the change in density reproduction capability of the printing press by measuring the density of the image formed on the photosensitive medium. The purpose is.

1 is a cross-sectional view showing a printing press according to the present invention,

FIG. 2 is a diagram illustrating an example of a configuration of the photodetector of FIG. 1;

FIG. 3 is a graph illustrating output values of components for each color of the photodetector for a test image for each density of cyan color formed on the photosensitive medium by the printer of FIG. 1;

FIG. 4 is a graph illustrating output values of components of color of the photodetector for test images of concentrations of magenta color formed on the photosensitive medium by the printer of FIG.

FIG. 5 is a graph illustrating output values of components for each color of the photodetector for a test image for each density of a yellow color formed on the photosensitive medium by the printer of FIG. 1;

FIG. 6 is a graph illustrating output values of components for each color of the photodetector for a test image for each density of a black color formed on the photosensitive medium by the printer of FIG.

7 is a graph showing the result obtained by subtracting the cyan component from the magenta component in the graph of FIG. 4,

8 is a graph illustrating a result obtained by subtracting a cyan component from a yellow component in the graph of FIG. 5,

FIG. 9 is a graph illustrating a result obtained by subtracting a cyan component from a yellow component in the graph of FIG. 6.

10 is a flow chart showing a concentration measurement process according to the present invention.

<Explanation of symbols for the main parts of the drawings>

11: photosensitive belt 12: static eliminator

13: charging machine 14 to 17: optical scanning device

18 to 21: developer 22: drying apparatus

23: transfer device 24: paper

30: light detector 40: concentration calculator

50: controller 60: input panel

In order to achieve the above object, according to the present invention, a developing device for developing a photosensitive medium, an optical scanning device for irradiating light to the photosensitive medium, and an electrostatic latent image formed by the optical scanning device on the photosensitive medium with a developing material. And a printer for controlling the overall printing machine, wherein the printer is installed to detect light incident from a test image formed on the photosensitive medium by the optical scanning device and the developing device, and is included in the received light. A light detector for separating and outputting the color component from the main color component and the sub color component; And a concentration calculating unit which obtains a density value of the test image corresponding to a result obtained by subtracting a sub-color component from the main color component output from the photodetector from a reference table and outputs it to the controller. The optical scanning device and the developing device are controlled to form the test image on the photosensitive medium.

In addition, in order to achieve the above object, a method for measuring the density of an image formed on a photosensitive medium of a printing press according to the present invention includes a photosensitive medium, an optical scanning device for irradiating light onto the photosensitive medium, and the optical scanning on the photosensitive medium. A developing device for developing an electrostatic latent image formed by the device with a developing material, and installed to detect light incident from an image formed on the photosensitive medium, and separating the color component included in the received light into a main color component and a sub color component. A method for measuring the density of an image formed on the photosensitive medium of a printing press, comprising a light detector for outputting and a density calculator for calculating a density value of the image from color components output from the light detector. Forming a test image of a color to be measured on the photosensitive medium; I. Detecting incident light from a test image formed on the photosensitive medium; All. Calculating a concentration of a set main color component and a set sub-color concentration among the color components included in the light detected in the step Na; la. And calculating the density of the test image from the result obtained by subtracting the sub-color components from the main color components calculated in the multi-step.

Hereinafter, with reference to the accompanying drawings will be described in more detail the printing press according to a preferred embodiment of the present invention and a method for measuring the density of the image formed on the photosensitive medium.

1 is a cross-sectional view showing a printing machine according to the present invention.

Referring to the drawings, the printing machine includes a printing engine, a light detector 30, a concentration calculator 40, a controller 50, and an input panel 60.

The printing engine is provided with a photosensitive belt 11, a static eliminator 12, a charger 13, a optical scanning device 14 to 17, a developing device 18 to 21, a drying device 22, and a transfer device 23. do.

The static eliminator 12 irradiates light on the photosensitive belt 11 to remove the electrostatic latent image remaining on the photosensitive belt 11.

The charger 13 charges the photosensitive belt 11 to a predetermined small potential so that a new electrostatic latent image can be written on the photosensitive belt 11.

The optical scanning devices 14 to 17 scan yellow, magenta, cyan and black color image information onto the photosensitive belt 11, respectively.

The developing units 18 to 21 respectively supply yellow, magenta, cyan and black developing solutions to the photosensitive belt 11 to develop an electrostatic latent image.

The transfer device 23 transfers the image formed on the photosensitive belt 11 to the paper 24.

The photodetector 30 is installed at a position capable of detecting light incident from the image 35 formed of the developing material on the photosensitive belt 11. In the example shown, the photodetector 30 is provided between the drying apparatus 22 and the transfer apparatus 23.

The light detector 30 is configured to detect light incident from the image 35 formed on the photosensitive belt 11 through a developing process, and separately output color components included in the detected light. As illustrated in FIG. 2, the photodetector 30 may include a plurality of sensors to detect components of different colors with respect to incident light. For example, the first sensor 31 detects and outputs only the yellow color component of the incident light, the second sensor 32 detects and outputs only the magenta color component of the incident light, and the third sensor 33 receives the incident light. It is configured to detect and output only the cyan color component. In FIG. 2, reference numeral 35a denotes a test image.

The density calculator 40 receives the color components output from the photodetector 30, and records the concentrations corresponding to the difference between the input color component information and the main color component and the sub color component recorded in the lookup table 40a. The density of the inspection target image is calculated using the value.

The controller 50 is to control the overall printing press. When the development concentration diagnosis mode for checking the image density reproducibility of the printing press is required, the controller 50 controls the printing engine and the concentration calculating section 40, and the concentration calculating section 40 The change in image reproduction ability is judged from the density value output from

The progress request of the developing concentration diagnostic mode may be set by the user by operating the input panel 60. Alternatively, the developer concentration diagnostic mode may be automatically performed whenever the controller 50 internally sets a condition. For example, the developer concentration diagnosis mode may be set every time the printer is turned on, or every set number of prints, for example, 1000 prints.

When the developing concentration diagnosis mode is set, the controller 50 controls the printing engine to form a test image having a set density on the photosensitive belt 11, and controls the density value calculated for the test image from the concentration calculation unit 40. It determines whether the density reproducibility of the printer changes.

An image concentration measurement process of such a printer will be described in more detail with reference to FIGS. 3 to 10.

FIG. 3 shows 20 test pattern image patches on the photosensitive belt 11 to be spaced apart from each other by a predetermined distance such that the density value is 5% on the blue photosensitive belt 11 using a printing press having a normal density reproduction capability. After forming, it is a graph showing the color component value output from the photodetector 30 for each pattern image.

As can be seen from the graph of FIG. 3, the values of the monochromatic components output from the photodetector 30 for the test pattern image patches formed on the photosensitive belts 11 at different concentrations correspond to one-to-one correspondences. It can be seen that the same value is output for different concentrations. Therefore, the monochromatic component output from the photodetector 30 cannot accurately calculate the density value of the inspection target image.

3 to 6, the image of the test pattern is developed in magenta, yellow, and black under the same conditions as in FIG. 3, and the output values for each color of the light detector 30 corresponding to the developed test pattern image are shown in FIGS. 4 to 6. In the graphs of FIGS. 4 to 6, it can be seen that an output value of each color component of the photodetector 30 does not correspond one-to-one to the density of the test pattern image.

On the other hand, the result obtained by subtracting the cyan component from the magenta component among the data values of FIG. 3 is shown in FIG. In FIG. 7, a result value corresponding to the difference in density of the test pattern image patches was obtained.

8 is a graph illustrating a result obtained by subtracting a cyan component from a yellow component in the graph of FIG. 5, and FIG. 9 is a graph illustrating a result obtained by subtracting a cyan component from a yellow component in the graph of FIG. 6. 8 and 9 also obtained results corresponding to the difference in density between the yellow test image patch and the black test image patch.

As a result, in the present invention, a monochromatic inspection target image is formed on the photosensitive belt 11, and then the density of the inspection target image is measured from the result obtained by subtracting two mutually different components of light incident from the inspection target image. . Here, the color component to be subtracted is called a main color component, and the subtraction component is called a subcolor component.

For example, when the result of FIG. 7 is to be applied, the main color component may be set to magenta, and the sub color component may be set to cyan for the mode for checking the density reproducibility of magenta color. Similarly, when the result of FIG. 8 is to be applied, the main color component is set to yellow and the sub color component is set to cyan for the mode for checking the density reproducibility of the yellow color. In this case, the main color component is set to yellow and the sub color component is set to cyan for the mode of checking the density reproducibility of the black color. And the result data of FIGS. 7-9 is recorded in the lookup table 40a.

Then, as an example, the density measurement process of the image for checking the yellow color reproducibility will be described with reference to FIG. 10.

First, if it is determined that the development concentration diagnostic mode, the set test pattern image is formed on the photosensitive belt 11 (step 100). For example, when the internal test pattern image data is set to form a test pattern image of 10% concentration on the photosensitive belt 11, the controller 50 first controls the optical scanning device 14 to control the image data of 10% concentration. The light corresponding to this is to be scanned on the photosensitive belt (11). The electrostatic latent image of the test image formed by the light scanned on the photosensitive belt 11 is developed by the developer 18 supplying a yellow developer.

When the test image formed on the photosensitive belt 11 reaches the light receiving region of the photodetector 30, the photodetector 30 detects light incident from the test image forming region and separates the color components included in the detected light. And output (step 110).

On the other hand, the controller 50 provides the concentration calculation unit 40 with information that the color of the current inspection target image is yellow.

The concentration calculation unit 40 subtracts a cyan component, which is a sub-color component, from a yellow color component, which is a set main color component, among the color components output from the photodetector 30. Then, the density value corresponding to the result value obtained by subtracting the cyan component from the yellow component is found in the lookup table 40a to calculate the density value of the test image (step 120). The controller 50 compares the concentration value of the development result input and calculated by the concentration calculation unit 40 with a target density value (10% in the above example) set when the test image is formed to determine the density reproduction capability of the printer. The density reproducibility determination result can be displayed through a display device (not shown) of the printing press or used to adjust operating conditions so that each device can normalize the print density reproducibility.

Determination of density reproduction ability for other colors is performed in the same way.

As described above, according to the printing press and the density measuring method of the image displayed on the photosensitive medium according to the present invention, the image density reproducibility of the printing press can be precisely measured, and thus it can be used to determine the change in printing capability of the printing press. .

Claims (8)

A photosensitive medium, a light scanning device for irradiating light to the photosensitive medium, a developing device for developing an electrostatic latent image formed by the light scanning device on the photosensitive medium with a developing material, and a controller for controlling the overall printing machine. In the printing press, The photodetector is installed to detect the light incident from the test image formed on the photosensitive medium by the optical scanning device and the developing device, and outputs the color component included in the received light by separating the primary component and the secondary component. Wow; And a density calculating section for obtaining a density value of the image corresponding to a result obtained by subtracting a sub-color component from the main color component output from the photodetector from a reference table and outputting it to the controller. And the controller controls the optical scanning device and the developer so that the test image is formed on the photosensitive medium. The printer according to claim 1, wherein the main color component is a magenta color component and the sub color component is a cyan color component when the test image is developed in magenta color. The printer according to claim 1, wherein the main color component is a yellow color component and the sub-color component is a cyan component when developing the test image in a yellow color. The printer according to claim 1, wherein the main color component is a yellow color component and the sub-color component is a cyan component when developing the test image in a black color. A photosensitive medium, an optical scanning device for irradiating light to the photosensitive medium, a developing device for developing an electrostatic latent image formed by the optical scanning device on the photosensitive medium with a developing material, and an incident image from a test image formed on the photosensitive medium. A light detector configured to detect light and separate and output a color component included in the received light into a main color component and a sub-color component, and a density calculation to calculate a density value of the image from the color component output from the light detector In the method for measuring the density of the image formed on the photosensitive medium of the printing machine having a portion, end. Forming a test image of a color to be measured on the photosensitive medium; I. Detecting incident light from a test image formed on the photosensitive medium; All. Calculating a concentration of a set main color component and a set sub-color concentration among the color components included in the light detected in the step Na; la. Calculating a density of the test image from a result obtained by subtracting the sub-color components from the components of the main colors calculated in the multi-step; and measuring the density of the image formed on the photosensitive medium of the printing machine. . The printer according to claim 5, wherein the main color component is a magenta component and the sub color component is a cyan component when developing the test image in magenta color. The printer according to claim 5, wherein the main color component is a yellow color component and the sub-color component is a cyan component when developing the test image in a yellow color. 6. The printing machine according to claim 5, wherein the main color component is a yellow color component and the sub-color component is a cyan component when developing the test image in a black color.