JPS6029255Y2 - Recording light source in image scanning recording device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a recording light source in an image scanning recording device such as a color scanner for plate making or a color facsimile.

Conventionally, a photographic method using a plate-making camera has been used to create color separation plates in photolithography for multicolor printing. ), the color separation results are not stable, the quality tends to be uneven, and the masking process is complicated.

Therefore, electronic color separation machines, so-called color scanners, have become popular, and these color scanners are now the mainstream.

As a recording light source, which is the output system of this color scanner,
Generally, light modulating discharge tubes are used, but these discharge tubes have poor frequency characteristics to be used as recording light sources.
There are disadvantages such as high operating voltage and large size compared to semiconductor devices.

Recently, so-called direct scanners have been developed that use a laser beam or xenon light source as the recording light source of a scanner to directly reproduce a mesh image on a photosensitive material, but laser light sources and xenon light sources are expensive. There are disadvantages such as being expensive, requiring a large number of complex modulation devices, and increasing the size of the device itself.

On the other hand, the availability of a light source such as a light-emitting diode that is small, does not require a complicated modulation device, and has good frequency characteristics is particularly advantageous for direct scanners, but this type of light source has low brightness. Since it is relatively low, there is a drawback that it is not possible to obtain an exposure amount sufficient to maintain current practical scanning speeds.

The present invention eliminates the disadvantages of these conventional recording light sources by making it possible to use a light modulation light source with relatively low brightness, and will be described below with reference to the drawings.

FIG. 1 is a block diagram of a color scanner to which a recording light source according to the present invention is applied.

A color original wrapped around an original cylinder 1 which is rotationally driven by an electric motor 2 is brought close to the cylinder 1 by a feed screw 6 connected to an electric motor 4 and rotated in its axial direction (
The image signals scanned and picked up by the scanning head 5, which is sequentially moved in the sub-scanning direction), are R (red), G (
After color separation into green) and B (blue), the image signal is converted into an electrical image signal by a photoelectric conversion element such as a photomultiplier tube, and the image signal is input to the arithmetic circuit 13.

This arithmetic circuit includes a storage device in which the writing and reading timing of image signals is controlled by each pulse from the scanning side pulse generator 3 and the recording side pulse generator 9 according to the set magnification, and the input image signal. It includes a color correction circuit and gradation correction circuit to make it suitable for printing.

The image signal processed by the arithmetic circuit 13 is transmitted through a delay circuit device 14 (described later) to modulate and control the light emission of the recording light source of the recording head, which is transported in the sub-scanning direction by a feed screw 12 connected to the electric motor 10. , color separation plates are recorded on a photosensitive material on a recording cylinder 7 which is rotated in synchronization with the original image cylinder 1 by an electric motor 8.

The recording light source device according to the present invention is built in a recording head 11, and as shown in FIG.
6. A plurality of imaging optical systems are arranged at equal intervals in the main scanning direction and are composed of a light shielding plate 17 having an aperture of a required diameter and an imaging lens 18.
Four recording light source devices 20a, 20b, 20c, 2Od
are arranged at equal intervals in the circumferential direction (main scanning direction) of the recording cylinder 7 and at equal distances from the surface of the cylinder.

In this way, a plurality of recording light source devices are connected to the recording cylinder 7.
The reason why they are arranged at equal distances from the circumferential surface of the cylinder 1 is that multiple recording light source devices are used to apply multiple exposures to the same location on the wrapped photosensitive material 19 of the cylinder 1. This is to eliminate the lack of brightness, and the number can be increased or decreased depending on the required brightness.

Since a plurality of recording light source devices according to the present invention are installed together as shown in FIG. 2, for example, when rotating the recording cylinder 7 at a constant speed n (rps), the angle α formed by each light source device is radian] is α/2
? rn (sec), and a corresponding delay circuit device must be provided.

However, in a delay circuit using a general delay element, rotation unevenness occurring in the recording cylinder 7 causes duplication in the reproduced picture due to a shift in exposure position, which is undesirable. The circuit device 14 is connected to the required number of storage devices 21 and 2 as shown in the third diagram.
2.23 and the counter 30 The timing of writing and reading image signals to and from these storage devices is controlled to correspond to the position of each recording light source device, without being affected by uneven rotation of the cylinder 7. This allows for accurate multiple exposure.

FIG. 4 is a time chart of pulse signals that control writing and reading of image signals to and from each of the storage devices 21, 22, and 23, in which a is a clock pulse obtained by appropriately multiplying the output of the recording side pulse generator 9, and b is a clock pulse that is multiplied appropriately. Recording cylinder 7-1
The start pulse C generated at a fixed position every rotation is a counter pulse generated when the counter 30 counts the required number of clock pulses a.

When the recording cylinder 7 rotates and the start pulse b is input to the delay circuit device 14, the image signal of the first pixel is first added as is to the first light source device 20a, and simultaneously written to the first stage storage device 21. Then, the image signal of the subsequent pixel is processed according to the timing of clock pulse a.
They are sequentially added to the light source device 20a and written to the storage device 21.

Next, when the count value of the clock pulse a by the counter 30 reaches a certain value, the first pulse 24 of the counter pulses C is inputted to each storage device 21, 22, 23, and thereby the first stage storage device The image signals stored in 21 are sequentially read out according to the clock pulse a, and the second
The data is added to the second stage light source device 20b and written to the second stage storage device 22.

When the count value of the counter 30 further advances and the pulse 25 is input to each storage device, the image signals stored in the second stage storage device 22 are sequentially read out according to the clock pulse a, and the third light source device 20c, and the third
The data is written to the storage device 23 of the second stage.

When the count value of the counter 30 further progresses and the pulse 26 is input to each storage device, the image signal stored in the third stage storage device 23 is sequentially read according to the clock pulse a, and the fourth light source device 20d.

Hereinafter, the counter 30 outputs a counter pulse C every time it counts a certain number of clock pulses a.
The subsequent pulses are not directly related to the writing and reading of the storage devices, and image signals are continuously written and read in each storage device 21, 22, and 23 in sequence according to the timing of the clock pulse a. .

Therefore, a certain number of counted values by the counter 30 are set to values corresponding to the arrangement interval of each light source device, that is, when the part of the photosensitive material exposed by the previous light source device reaches the exposure position by the next light source device. If the count value of the counter 30 is selected so that the same image signal as the previous image signal is applied at that time, the photosensitive material is exposed to the same image multiple times by the number of light source devices.

Since the clock pulse a is given by the pulse generator 9 which is driven in synchronization with the rotation of the recording cylinder 7, even if rotational unevenness occurs in the cylinder 7, the exposure positions by each light source device can be completely matched. There is no risk of image shift occurring when a simple delay circuit is used.

In addition, the capacity of each storage device may be such that it can store an image signal corresponding to the start pulse and the counter pulse, or the interval between the counter pulses, with some margin. As the memory becomes full, data is written to the first address in sequence.

Although the above description has been made regarding the case where color separation plates of a color original are simply recorded by duplication, the recording light source device according to the present invention can also be applied to the case where halftone color separation plates are directly created.

That is, by closely superimposing a contact screen on the photosensitive material 19 wound around the recording cylinder 7 shown in FIG. 2, it is possible to record a mesh plate. The image signal is divided into fine pixels and stored in a storage device as a halftone dot signal, and the halftone signal is read out using the address signal and 17, and the halftone signal is replaced with the image signal. It is possible to apply this method to a light source device for commercial use.

As described above, since the recording light source device of the present invention uses a semiconductor light emitting element, it is extremely easy to drive and inexpensive compared to conventional devices, and also has low brightness. Since the optically modulated light source itself is extremely miniaturized, it is advantageous in terms of space and has many practical effects.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an image scanning recording device to which the recording light source of the present invention is applied, FIG. 2 is a partially longitudinal side view showing an example of the recording light source device of the present invention, and FIG. A diagram showing an example of the delay circuit device shown in FIG. 1, and FIG. 4 is a time chart of FIG. 3. 1... Scanning cylinder 5... Scanning head, 7... Recording cylinder, 11...
- Recording head, 13... Arithmetic circuit, 14...
... Delay circuit device, 15 ... Low brightness light modulation light source 16 ... Condenser lens, 17 ... Light shielding plate, 18 ... Image forming lens , 19...
Photosensitive material, 21, 22, 23... Storage device, 3
0... Counter.

Claims (1)

[Claims for Utility Model Registration] <11 A recording head that moves relatively in the sub-scanning direction in close proximity to the recording cylinder is placed on a photosensitive material wound around a rotating recording cylinder in response to an image signal from an original image. An image scanning recording device configured to record a duplicate image using a plurality of low-intensity light sources built into the recording head and arranged at equal intervals in the main scanning direction, and an image forming optical means for each light source. A plurality of light source devices whose light emission is modulated by the signal, and a rotation amount of the recording cylinder corresponding to the interval between the low brightness light sources on the photosensitive material for controlling the timing of supplying the image signal to each light source. A recording light source in an image scanning recording device comprising a delay circuit device that provides a delay amount of the number of clock pulses. (2) The recording light source according to claim (1), wherein the low-intensity light modulation light source is constituted by a light emitting diode.