KR100313868B1 - Optical scanning system of the printing press - Google Patents

Abstract

An optical scanning system of a printing press is disclosed. The optical scanning system has a circulating motion, a photosensitive medium having a slit portion in which a light transmitting portion and a light blocking portion are alternately arranged along a direction intersecting at a predetermined angle with respect to the traveling direction, and a predetermined length thereof, and the traveling direction of the photosensitive medium. At least one optical scanning device that scans light along a main scanning direction intersecting at a predetermined angle with respect to the photosensitive medium, and receives light passing from the optical scanning device opposite the optical scanning device centering on the photosensitive medium and passing through the light transmitting portions of the slit part And a light receiving unit for outputting an electrical signal corresponding thereto, and the light arriving at the pixel position set in the photosensitive medium from the input times of the electrical signals output in response to the light reception of the light passing through the light transmitting portions sequentially from the light receiving unit. Obtaining light emission time data for each pixel of the optical scanning device internally, and for each pixel In normal printing by the time data and a Gwangju Co. fisherman for controlling the light output timing of the scanning device corresponding to the image information. According to the optical scanning system of the printing press, the light emission start data for each pixel required to emit light to the pixel position set on the photosensitive medium can be obtained internally, thereby improving the printing quality, and Even after replacement of the yarn device, the operator does not have to perform a separate operation for matching the color registration, thereby improving convenience.

Description

Optical scanning system of the printing press

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light scanning system of a printing press, and more particularly, to a light scanning system of a printing press capable of automatically calculating pixel-specific light scanning time data for reaching light at a pixel position set on a photosensitive medium.

1 is a view showing a general wet color printing machine using a belt.

Referring to the drawings, the reset device 15, the optical scanning device 30, 40 (adjacent to the circulation path of the photosensitive belt 14 circulating by the plurality of rollers 11, 12, 13) ( 50, 60, photodetectors 38, 48, 58, 68, developer 36, 46, 56, 66, drying device 18, transfer device 20 It is placed at a certain distance. Reference numeral 15a denotes an exposure apparatus for erasing the electrostatic latent image, and reference numerals 15b, 37, 47, and 57 denote chargers for charging the photosensitive belt to a predetermined potential to enable the electrostatic latent image writing.

Looking at the printing process, first, when the tip of the image writing page area set on the photosensitive belt 14 reaches the dice of the first optical scanning device 30 via the reset device 15, the first optical scanning device 30 ) Scans light with yellow color image information. The electrostatic latent image formed on the photosensitive belt 14 by the first light scanning device 30 is developed by the first developing unit 36 which supplies the developer Y of yellow color. When the page area on the photosensitive belt 14 is charged by the charger 37 so that a new electrostatic latent image can be written, and then reaches the dice of the second optical scanning device 40, the second optical scanning device ( 40) scans light for image information of magenta color. The electrostatic latent image formed on the photosensitive belt 14 by the second light scanning device 40 is developed by the second developing unit 46 which supplies the developer M of magenta color.

This process includes the third and fourth light scanning devices 50 and 60 for scanning cyan and black image information, and supplying the corresponding cyan and black developer C and BK. And the fourth developer 56, 66. As a result, a color image is formed on the photosensitive belt which has passed through the fourth developer 66. The color image formed of the developing material on the photosensitive belt 14 is firstly transferred to the transfer roller 21 through which the photosensitive belt 14 and a part thereof are rotated through the drying device 18 for removing the liquid carrier element. Is transferred. Subsequently, the color image transferred to the transfer roller 21 is secondarily transferred to the paper 23 entering between the transfer roller 21 and the fixing roller 22.

On the other hand, the optical scanning device 30, 40, 50, 60 are each configured to emit light while gradually changing the angle within a predetermined angle range. In general, the optical scanning devices 30, 40, 50, and 60 that are commonly used include a light source, a rotating polygon mirror and a lens unit, and a hologram disk instead of the rotating mirror mirror.

The optical scanning devices 30, 40, 50, and 60 are rotated at a constant speed in order to sequentially scan the optical signals corresponding to the image information for each pixel position set on the photosensitive belt 14. The light emission timing control of the light source which emits light with respect to a rotating facet mirror or a hologram disk is calculated | required.

In particular, a color printing machine provided with a plurality of optical scanning devices 30, 40, 50, 60 so as to scan different color information with respect to the photosensitive belt 14, which is a circulating photosensitive medium, while maintaining a predetermined distance. In this case, if the optical signal emitted from each optical scanning device 30, 40, 50, 60 is not controlled to reach the same pixel position set on the photosensitive belt 14, the pattern by color is mutually different. It cannot shift and obtain a desired image.

In this way, the color restoring error means that the images for each color are written shifted from the pixel image writing position set on the photosensitive belt 14.

In order to correct such a color registration error, conventionally, after instructing to print an image of a set test pattern, the inspector directly measures the distance difference between the test patterns for each color output on the paper 23, and therefrom a registration error. The amount was calculated. However, this method has the disadvantage that the operator has to calculate the registration error amount directly, and that the artificial error is likely to be included in the error amount calculation.

The present invention was devised to solve the above problems, and the optical quality of the optical scanning device can internally calculate light emission timing data for each pixel required to emit light to a pixel position set on the photosensitive medium, thereby improving print quality. The purpose is to provide an optical scanning system of the printing press to improve.

1 is a cross-sectional view showing a typical wet color printing press,

Figure 2 is a perspective view showing a light scanning system of the printing machine according to the present invention,

3 is a partial excerpt perspective view of the optical scanning system of FIG.

4 is a waveform diagram illustrating the optical scanning process of the optical scanning system of FIG.

5 is a cross-sectional view showing still another configuration example of the light receiving unit of the optical scanning system of FIG.

<Explanation of symbols for main parts of the drawings>

11, 12, 13: roller 14, 74: photosensitive belt

15: reset device 15b, 37, 47, 57: charger

18: drying apparatus 20: transfer apparatus

21: transfer roller 22: fixing roller

23: paper 30, 40, 50, 60: optical scanning device

31, 41, 51, 61: light source 32, 42, 52, 62: rotating face mirror

33, 43, 53, 63: Lens units 36, 46, 56, 66: Developer

38, 48, 58, 68, 85: photodetector 75: slit portion

75a: light transmitting portion 75b: light shielding portion

81, 82, 83, 84: Light receiving part 86: Optical concentrator

90: optical fiber control unit 91: memory

According to the present invention for achieving the above object, at least one optical scanning device for scanning the light along the main scanning direction intersecting at a predetermined angle with respect to the traveling direction of the photosensitive medium, and the optical fiber In the optical scanning system of the printing machine having a optical scanning control unit for controlling the driving of the scanning device, the light transmitting portion and the light blocking portion are alternately arranged in a predetermined length on the photosensitive medium along a direction intersecting at a predetermined angle with respect to the traveling direction. A formed slit portion; And a light receiving unit opposite the optical scanning device centered on the photosensitive medium, receiving the light emitted from the optical scanning device and passing through the light transmitting portions of the slit part and outputting an electrical signal corresponding to the optical scanning control unit. And the optical scanning controller is required to allow light to reach a pixel position set in the photosensitive medium from input times of electrical signals output in response to the reception of light sequentially passing through the light transmitting portions from the light receiving portion. It is characterized in that the light emission time data for each pixel of the scanning device is obtained internally, and the light emission time of the optical scanning device corresponding to the image information during normal printing is controlled by the light emission time data for each pixel.

Preferably, the photodetector further includes a photodetector for receiving the light from the optical scanning device toward the position outside the photosensitive medium at a fixed position and outputting a signal corresponding to the received light to the optical scanning controller. In addition, the optical scanning controller is provided with a memory for storing the light emission time data for each pixel.

Hereinafter, the optical scanning system of the printing press according to a preferred embodiment of the present invention with reference to the accompanying drawings in more detail.

Figure 2 is a perspective view showing a light scanning system of a printing press according to the present invention. Elements having the same function as in the above-described drawings are denoted by the same reference numerals.

Referring to the drawings, the optical scanning system is circulated by a plurality of rollers (11, 12, 13), and a photosensitive belt (74) having a slit portion (75) formed at a portion thereof, and the photosensitive belt (74). A plurality of light scanning devices 30, 40, 50, 60 for scanning light and a plurality of light receiving light emitted from the light scanning devices 30, 40, 50, 60 at a fixed position. Light detectors 38, 48, 58, 68, and light receiving portions 81, 82, 83, 84 provided to receive light passing through the slit portion 75, and optical fiber A fisherman 90 is provided.

The photosensitive belt 74 forms an electrostatic latent image in response to incident light, and a slit portion 75 is provided at a portion thereof. The slit portion 75 is an area not used for image writing, and a plurality of light-transmitting portions 75a and light-shielding portions 75b are alternately formed along the main scanning direction, which is a direction perpendicular to the traveling direction of the photosensitive belt 74. have. The light transmitting portion 75a of the slit portion 75 may be formed in the form of a through hole, and preferably formed of a transparent material. The light blocking portion 75b is formed of a light blocking material by using a printing technique. The light-transmitting portion 75a is formed to be as fine as possible at equal intervals, for example, preferably to maintain a pixel interval or several times the distance thereof.

The optical scanning devices 30, 40, 50, and 60 are light sources 31, 41, 51, 61, rotating mirrors 32, 42, 52, 62, and lenses, respectively. Units 33, 43, 53 and 63 are provided. The optical scanning device 30, 40, 50, 60 includes a scan disk (not shown) in which a hologram pattern is formed so as to deflect incident light, and a light source for emitting light to the scan disk that is rotated. It may be configured.

The photodetectors 38, 48, 58, 68 are arranged to detect light directed from the edge of the photosensitive belt 74 to the edge from a position away from the predetermined distance.

The light receiving parts 81, 82, 83, and 84 are installed on the photosensitive belt 74 by being disposed to face each of the optical scanning devices 30, 40, 50, and 60 behind the photosensitive belt 74. The light passing through the light transmitting portion 75a of the slit 75 is received and outputs an electrical signal corresponding thereto. The light receiving units 81, 82, 83, and 84 array photodetection cells at positions facing the light transmitting portions 75a, and output a signal corresponding to light reception for each photodetection cell 90. The light detector 85 may be configured to be output to the light detector 85, and is scanned from the photodetector 85 made of one light receiving cell and the optical scanning device 30, 40, 50, 60, and each light transmitting portion 75a. May be provided with a light concentrator 86 for focusing light passing through the light into the light receiving region of the photodetector 85. The light concentrator 86 applied in FIG. 5 is a reflecting mirror.

The optical scanning controller 90 controls the optical scanning apparatus 30, 40, 50, 60 so that the light corresponding to the image information can reach the pixel position set on the photosensitive belt 74. In addition, when the self-diagnosis request signal is generated, when the slit portion 75 on the photosensitive belt 74 reaches the dice of each optical scanning device 30, 40, 50, 60, As a result, the light receivers 81, 82, 83, and 84 receive a signal output corresponding to the light transmission of each light transmitting portion 75a, and internally update the light emission timing data for each pixel. The self-diagnosis request signal may internally correspond to an instruction to calculate pixel-based light emission time data, and may be generated internally in the optical scanning controller 90 at a set period or at a warm-up period performed after power is turned on. In addition, you may be able to receive an instruction from an external source. In order to receive the self-diagnosis request signal from the outside, a self-diagnosis key capable of transmitting the self-diagnosis request signal to the optical scanning control unit 90 is provided on an operation panel (not shown) which is an input device provided outside the main body of the printer. In the case of a printer used in connection with a computer, a user can transmit a self-diagnosis request signal to the printer with the help of a printer driver program installed in the computer.

When the self-diagnosis request signal is generated, the process of calculating the optical scan timing data for each pixel of the optical scan controller 90 will be described. The process of obtaining the optical scanning time data for each pixel in the main scanning direction of each optical scanning device 30, 40, 50, 60 is performed by the light transmitting portion 75a of the slit portion 75 provided on the photosensitive belt 74. Since they are obtained from the time data passed through them, there is a time difference, but the methods are the same. Therefore, the process of obtaining the optical scanning time data for each pixel for one optical scanning device 30 will be described with reference to the drawings of FIG. 3.

First, the rollers 11, 12 and 13 are driven to circulate the photosensitive belt 74 at the same speed as in the printing operation. When the photosensitive belt 74 proceeds at the set feed speed, the light scanning device 30 is driven to continuously emit light from the light scanning device 30. When the slit portion 75 provided on the photosensitive belt 74 reaches the dice of the optical scanning device 30 in the process of continuously emitting light from the optical scanning device 30, first, the photosensitive belt 74 is removed. The pulse signal corresponding to the light reception is output from the photodetector 38 which receives the light directed to the off position. The pulse signal corresponds to the light reception from the position out of the photosensitive belt 74 to the edge of the photosensitive belt 74 in the scanned light. After outputting the pulse signal, a signal corresponding to the reception of light passing through the transmissive portion 75a which is first placed in the main scanning direction is output from the light receiving portion 81. Subsequently, a signal corresponding to light reception of the light passing through the second, third, ..., and the last light transmitting portions 75 is sequentially output from the light receiving portion 81. In this way, the input time of the signal output in response to the light transmission of each light transmitting portion 75a in the light receiving portion 81 is stored in the memory 91 of the optical scanning controller 90. After the light emission from the light source 31 is started, the time stored in the memory 91 for the reaction time from the light receiving portion 81 to the input point of the signal output in correspondence with the light reception of the light passing through each light transmitting portion 75a. The light emission start time data for each pixel may be obtained by subtracting from. However, since the reaction time is negligible in consideration of the light speed and the electrical response speed, the time stored in the memory 91 is converted to the pixel light emission time. It may be used as it is as data.

In this case, when the separation distance P between the adjacent light transmitting portions 75a is set to a multiple of the pixel interval, the time inputted from the light receiving portion 81 in response to light reception for each light transmitting portion 75a is sequentially applied. 75a) The value obtained by equally dividing by the number of pixels located within the interval is used as the optical scanning data for each pixel.

For example, when the distance P between the adjacent light transmitting portion 75a includes four pixels, as shown in FIG. 3, the first light transmitting portion 75a based on the falling point of the pulse signal of the photodetector 38. The light reception signal corresponding to the light passage of the t) is input to t0, and the light reception signal corresponding to the light passage of the second light transmission portion 75a is t1, and the light reception signal corresponding to the light passage of the third light transmission portion 75a is t2. When inputted as, ..., time data such as t0, t1 * 1/4, t1 * 2/4, t1 * 3/4, t2 * 1/4, ..., It is finally stored in the memory 91 in the optical scanning control unit 90 as emission time data. The light emission timing data for each pixel thus calculated are used to control the image writing timing during normal printing. For example, when the first light-transmitting portion 75a corresponds to the first pixel corresponding to the image writing front end, when the normal image scanning is performed, as shown in FIG. 4, it is emitted from the optical scanning device 30 from the photodetector 38. When the pulse signal corresponding to the received light of the received light is input, the time corresponding to the light emission timing data for each pixel stored internally in the memory 91 after t0 time from the point of time when the pulse signal falls (in the example, t1 * 1/4 For each of t1 * 2/4, t1 * 3/4, t2 * 1/4, ..., the video clock signal VCLK is generated. The light source 31 is driven in synchronization with the video clock signal VCLK to emit light corresponding to the pixel-specific image data Vdata. When the image scanning for one line is finished, the driving of the light source 31 is temporarily stopped, and when it is time to emit light toward the photodetector 38, the light source 31 is turned on again until a pulse signal is output. Let's do it. Then, when the pulse signal is output, the driving of the light source 31 is temporarily stopped by the same method as described above, and when the t0 time has elapsed from the time when the pulse signal falls, the video clock signal VCLK outputs light corresponding to the image data of the next line. Drive the optical scanning device 30 in synchronization with ().

The same method is applied to the other optical scanning apparatuses 40, 50, and 60 for the process of calculating the light emission timing data for each pixel and the process of controlling the optical constant value from the light emission timing data calculated during normal printing. As a result, the pixel-specific light corresponding to the image information by the pixel-based light emission timing data each of the optical scanning devices 30, 40, 50, and 60 internally obtained for one slit portion 75 respectively. By controlling the emission time, each of the optical scanning devices 30, 40, 50 and 60 can reach the light corresponding to the image information to the pixel position set on the photosensitive belt 74 with respect to the main scanning direction. As a result, a desired color image can be obtained.

As described so far, according to the optical scanning system of the printing press according to the present invention, it is possible to internally obtain the light emission start data for each pixel required to emit light to the pixel position set on the photosensitive belt. In addition, the printing quality can be improved, and convenience is improved by not having to perform a separate operation for matching the color registration even after the replacement of the optical scanning device.

Claims (6)

A photosensitive medium that circulates, at least one optical scanning device that scans light along a main scanning direction that crosses a predetermined angle with respect to a traveling direction of the photosensitive medium, and a optical scanning control unit that controls driving of the optical scanning device. In the optical scanning system of the printing press, A slit portion on the photosensitive medium having a predetermined length formed by alternately arranging a light transmitting portion and a light blocking portion along a direction intersecting at a predetermined angle with respect to a traveling direction; And a light receiving unit opposite the optical scanning device centered on the photosensitive medium, receiving the light emitted from the optical scanning device and passing through the light transmitting portions of the slit part and outputting an electrical signal corresponding to the optical scanning control unit. Become, The optical scanning device is required to allow light to reach a pixel position set in the photosensitive medium from input times of electrical signals output in response to reception of light passing through the light transmitting portions from the light receiving part in sequence. And the light emission timing data of the optical scanning device corresponding to the image information at the time of normal printing by internally obtaining the light emission timing data for each pixel of the pixel. The optical detector of claim 1, further comprising a photodetector configured to receive light from the optical scanning device toward a position outside the photosensitive medium at a fixed position and output a signal corresponding to the received light to the optical scanning controller. The optical scanning system of the printing press. The optical scanning system of claim 1, wherein a memory for storing the light emission timing data for each pixel is provided in the optical scanning control unit. The optical scanning system of claim 1, wherein the light transmitting portion is formed of a transparent material. The display apparatus of claim 1, wherein the light receiving unit comprises: a photodetector configured to output an electrical signal corresponding to the received light; And a light concentrator for focusing the light passing through the slit to the light incident surface of the light receiving unit. The optical scanning system of claim 1, wherein the light transmitting portion is formed of a through hole.