JPH052258A - Input scanner for plate making - Google Patents

Abstract

PURPOSE:To prevent a read image from being distorted by coping with the shifting of a original on a scanner main body due to temperature variation in operation. CONSTITUTION:A picture element read means (e.g. pickup lens 27) for reading a fine area on the original 10 is coupled at a fixed position of a scanning head 12 by a coupling member 25 which meets requirements mentioned below. Namely, a) the coupling member is made of a material whose coefficient of heat expansion is equal to or larger than that of a cylinder material, b) the member is fixed to the scanning head 12 almost in parallel to the cylinder, and c) the member is fixed at only one end part (cantilever). A picture element read means is held at the other end part (free end). Then the coupling member expands or contracts similarly to the expansion and contraction of the cylinder, so the read position moves according to the movement of the original on the cylinder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate-making input scanner for reading an original such as a photograph, and more particularly to a scanner having a mechanism for preventing distortion of a read image due to temperature change.

[0002]

2. Description of the Related Art FIG. 7 shows a schematic block diagram of a plate making process including an input scanner, which will be briefly described below. 100 is an input scanner which is the subject of the present invention. This scanner 100 reads a document by moving a scanning (reading) head in parallel with the rotation axis of the cylinder while rotating a plastic cylinder having a document mounted on its peripheral surface.
Separates into three colors, G and R. Further, the scanner 100 is provided with a color operation circuit, performs processing such as color adjustment and tone adjustment on the color separation signals B, G and R, and outputs color plate signals of four colors Y, M, C and K. The color plate signals Y, M, C and K obtained by the input scanner 100 are given to the output scanner 200 or the editing system 300.

The editing system 300 is also called a layout system or layout scanner. Here, layout processing and correction of a plurality of originals are performed, and the output thereof is the output scanner 200 or the direct plate-making device 400.
Given to. The editing system 300 displays a monitor image by converting the color plate signals Y, M, C, K into memory means for storing the color plate signals Y, M, C, K into B, G, R. A monitor means for performing the layout is provided, and the layout processing and correction are performed with reference to the monitor image.

The output scanner 200 is an input scanner 10.
0 or color plate signals Y, M, from the editing system 300
C and K are converted into halftone dot signals and a halftone dot image is recorded on the film. Here, normally, a color plate film (color separation plate) for each color of Y, M, C and K is prepared.

This color plate film is collected together with a line drawing (character, figure, etc.) film prepared separately. Then, the plate-collected film is sent to the plate making apparatus 500. The printing plate creating apparatus 500 creates printing plates of four colors Y, M, C, and K.

The above-mentioned direct plate making apparatus 400 is a CTP (Co
Also referred to as "mputer ToPlate", based on the color plate signals Y, M, C, K from the editing system 300 and the line drawing information of characters and figures, Y, M directly without passing through the color plate film. , C, K four-color printing plates are created. These printing plates are sent to the next step of printing.

[0007]

In a normal plate-making input scanner, the cylinder is made of plastic, and the coefficient of thermal expansion of the plastic is generally very different from the coefficient of thermal expansion of the metal that constitutes most of the scanner body. When the temperature of the entire scanner changes, the plastic cylinder expands and contracts due to the difference in thermal expansion between the two, and the position of the document with respect to the scanner body shifts. An input scanner generally performs color separation (scanning) for four colors simultaneously by reading a document once, but since it is necessary to perform single color separation or two-color simultaneous separation for some reason, the document is read. May be divided into multiple times. As described above, when color separation (scanning) is performed a plurality of times on a single original, the positional deviation of the original with respect to the scanner main body caused by the temperature change becomes a problem. For example, in the first scan, 2 of Y and M
If the color plate signals of the colors are obtained and the color plate signals of the two colors C and K are obtained in the second scanning, distortion occurs between the color plate signals of both (ie, the read image).

That is, when these color plate signals are given to the output scanner 200 (FIG. 7) which is one of the output means,
As shown in FIG. 8, C for the Y (and M) version of the design
(And K) The design of the plate will be displaced. Therefore, the final printed matter is of no commercial value because it contains color shifts.

Incidentally, for reference, in the output scanner 200, in order to facilitate the registration of the patterns of the color separation plates of the respective colors, a register mark is provided outside (the margin part) of the image recording portion of each color separation plate. The ruled line called is recorded at the same time as the image. An example of the register mark is shown in FIG. In the example of FIG. 9, the register mark 50 is recorded just outside one side of the recorded image 53 and is parallel to the vertical ruled line 51 parallel to the main scanning direction (vertical direction in FIG. 9) and the sub-scanning direction (horizontal direction). It is composed of horizontal ruled lines 52.
Originally, the register mark must maintain a constant position with respect to the design throughout the color separation version. However, when the register mark is generated by the conventional scanner, the vertical ruled line 51 is generated when the scanning head comes to a predetermined position with respect to the scanner body. Therefore, as described above, if the single color separation or the two-color separation is performed plural times, the position of the register mark also shifts due to the color separation plate due to the displacement of the document with respect to the scanner body due to the temperature change.

Further, since the temperature rises rapidly immediately after the scanner is started, the temperature is different between the first half and the second half even during one scanning. In this case, not only the register mark but also distortion occurs in the part recorded in the first half and the part recorded in the latter half of one recorded color separation plate. In particular, when the recording magnification of the image is high, the amount of this "deviation" is enlarged, which is a serious problem.

The present invention has been made to solve such a problem, and an object of the present invention is to cope with a position shift of a document with respect to the scanner main body due to a temperature change during operation to read a read image. An object of the present invention is to provide an input scanner for plate making in which the occurrence of distortion is prevented.

[0012]

In the first structure of the present invention made to solve the above problems, a cylinder is rotatably held by the scanner body at only one end, and a document is mounted on the peripheral surface. A scanning head that is provided with a scanning head that is moved on the scanner main body in parallel with the rotation axis of the cylinder, and that supplies a color plate signal obtained by reading an original document to output means for recording or display. The pixel reading means for reading a minute area of the document, which is provided in the above, has the following conditions (a-1), (b-1), (c).
It is characterized in that it is connected to a fixed position of the scanning head by a connecting member that satisfies (A-1) It is arranged substantially parallel to the cylinder, and one end thereof is fixed to a fixed position of the scanning head. (B-1) The pixel reading means is held at the other end (free end). (C) It is made of a material having a thermal expansion coefficient equal to or higher than that of the cylinder material.

The pixel reading means referred to here reads only a very small area (pixel) in the image of the document (of course, the pixels to be read sequentially move on the document as the scanning head scans). It includes all elements provided in the scanning head to prevent reading light from other parts of the image, for example, a pickup lens that collects light from the pixel to be read, the position of the back focus of the pickup lens. Apertures, etc., placed in the area correspond to that.

It should be noted that which end (the end on the same side as the holding end of the cylinder or the end on the same side as the free end of the cylinder) of which the connecting member is fixed to the fixed position of the scanning head is connected. It depends on the type of pixel reading means held on the member.
For example, of the above, in the case of the pickup lens, it is necessary to move in the same direction as the movement of the pixel, so the end of the same side as the holding end of the cylinder is fixed at the fixed position of the scanning head, and in the case of the aperture the pixel is fixed. It is necessary to move it in the opposite direction to the movement of, so that the end of the cylinder on the same side as the free end is fixed in position in the scanning head.

According to a second structure of the present invention, instead of (a-1) and (b-1) of the first structure, a connecting member satisfying the following conditions allows the scanning head to serve as a running body. It is connected. (A-2) It is arranged substantially parallel to the cylinder, and one end of the cylinder is connected to a traveling body for moving the scanning head. (B-2) The scanning head is held at the other end.

[0016]

The scanning head is moved with respect to the scanner body, but when the cylinder expands and contracts due to the temperature change, the positional relationship with the cylinder changes. In the case of the scanner, the positional relationship with the cylinder is particularly problematic in the scanning head for reading a specific pixel of the document on the cylinder or the pixel reading means provided in the scanning head. Therefore, in the present invention, the scanning head or the pixel reading means is held by the connecting member satisfying the above conditions. Under the above conditions, the connecting member is substantially parallel to the cylinder and cantilevered, so that the cylinder expands and contracts in response to ambient temperature changes, and at the same time expands and contracts in the same direction or the opposite direction. Therefore, the movement of the pixel reading means can be made to follow the movement of the pixel or the movement of the optical image of the pixel by setting the direction of the fixed end of the connecting member to an appropriate direction according to the type of the pixel reading means and the scanning head. As a result, the desired pixel can always be read correctly regardless of the ambient temperature change.

Regarding the movement amount, according to the condition (c), since the coefficient of thermal expansion of the connecting member is the same as or larger than that of the cylinder, the movement amount of the scanning head or the pixel reading means must be the same as the movement amount of the original. If this is not the case, the expansion / contraction amount of the connecting member can be made the same as the expansion / contraction amount of the cylinder by adjusting the length thereof to an appropriate value which is the same as or shorter than that of the cylinder according to the coefficient of thermal expansion.

[0018]

FIG. 6 shows a schematic structure of an input scanner embodying the present invention. The basic structure of the input scanner of this embodiment is the same as that of the conventional input scanner, and a cylinder 11 and a cylinder 11 made of acrylic (polymethylmethacrylate) for mounting the document 10 on its outer peripheral surface or inner peripheral surface.
A scanning head 12 that scans the upper original 10 is mainly configured. The cylinder 11 is detachably fixed to the mount portion 13 on the scanner body side by a taper, and is rotated at a high speed by a main rotation motor (not shown). The rotation of the cylinder 11 is called main scanning. The main scanning position of the cylinder 11 is detected by the main rotary encoder 14, and the data thereof is sent to a control device (not shown) that integrally controls the operation of each part of the scanner, and the movement of the scanning head 12 described later is detected. Used for control.

A feed screw 15 is provided outside the cylinder 11 in parallel with its rotation axis, and the scanning head 12 is moved in parallel with the rotation axis of the cylinder 11 by the rotation of the feed screw 15. This movement of the scanning head 12 is called sub-scanning. The feed screw 15 is driven by a lateral feed motor 16 and a speed reducer 17 that reduces the rotation thereof. Traverse motor 16
Data of the rotational position of the scanning head 12, that is, the sub-scanning position of the scanning head 12 is also generated by the encoder 18 and sent to the above-mentioned control device. The control device moves the scanning head 12 at a constant speed based on the data from the main rotary encoder 14 and the lateral feed encoder 18.

The main body portion of the scanning head 12 is provided with a pickup lens 27 for receiving the light transmitted through the original 10 mounted on the cylinder 11 or reflected on the surface of the original 10 and the main body portion. From cylinder 1
A ray pipe 19 for a transmitted light source extends inside the cylinder 11 around the open end (right side in FIG. 6). In addition,
The reflected light source is generally provided around the pickup lens 27, but is not shown here. Further, the B, G, and R color separation signals obtained by the scanning head 12 are given to the color calculation circuit 20 and converted into Y, M, C, and K color plate signals.

An enlarged view of the scanning head 12 is shown in FIG. Irradiation light 24 is emitted from the tip of the lay pipe 19 toward the document 10 mounted on the peripheral surface of the cylinder 11. The irradiation light 24 transmitted through the original 10 is picked up by the pickup lens 27.
Enters the main body of the scanning head 12, passes through the aperture 28, and is guided to the photoelectric conversion unit. In the photoelectric conversion unit, red (R) and blue (B) light components of the light transmitted through the original are separated by a red selective reflecting mirror 30 and a blue selective reflecting mirror 32, respectively.
It is input to the photoelectric converters 31 and 33 of each color. The remaining green (G) light component from which the red and blue components have been removed is input to the corresponding photoelectric converter 35 by the total reflection mirror 34,
It is converted into an electric signal.

The characteristic point of this embodiment is that the pickup lens 27 is not directly attached to the main body of the scanning head 12 but via the connecting member 25 made of the same material (acrylic) as the cylinder 11. Scanning head 12
That is to be connected to the body of. The connecting member 25 is fixed to the scanning head 12 only at the end on the same side as the holding end of the cylinder 11 (left side in FIG. 1), and is held parallel to the rotation axis of the cylinder 11. The pickup lens 27 is attached to the tip of the connecting member 25, and the length from the attaching portion 26 of the connecting member 25 to the pickup lens 27 is about half the total length of the cylinder 11.

The operation of the connecting member 25 of this embodiment having the above structure will be described below. When the cylinder 11 expands and contracts with the change in the ambient temperature of the input scanner and the position of the document 10 moves, the connecting member 25 also expands and contracts and the position of the pickup lens 27 moves in the same direction. Manuscript 10
Is mounted substantially in the center of the cylinder 11, the amount of movement of the original 10 is half the amount of expansion and contraction of the entire length of the cylinder 11, and is equal to the amount of expansion and contraction of the connecting member 25 (that is, the amount of movement of the pickup lens 27). Become. As a result, the pickup lens 27 always emits light of a predetermined pixel on the original 10 regardless of the ambient temperature change.
It will be taken in.

Since the lay pipe 19 is fixed to the main body of the scanning head 12, the cylinder 1 is affected by the temperature change.
Even if the position 1 of the original 10 changes and the position of the original 10 changes, the irradiation of the position before the change continues, but as shown in FIG.
Since the size of the irradiation area of the irradiation light 24 above is larger than the size of the reading area by the pickup lens 27, there is no hindrance to the original reading with respect to the relative “deviation” between the irradiation position and the reading position. . The same applies to the aperture 28.

Although the material of the connecting member 25 is the same as that of the cylinder 11 in the above embodiment, the connecting member 2 is made of a material having a higher coefficient of thermal expansion than the material of the cylinder 11.
5 can be shortened, and the protruding length of the mounting portion 26 of the connecting member 25 from the main body of the scanning head 12 can be shortened. For example, an acrylic cylinder 1
When the connecting member 25 is made of polyethylene for 1,
The length of the connecting member 25 can be reduced to about half.

The same effect can be obtained by connecting not only the pickup lens 27 but also the entire scanning head 12 to the sub-scanning traveling body by a connecting member. Figure 3
Shown in. In this example, the half nut 23 as a running body that meshes with the feed screw 15 and the scanning head 12 are connected by the connecting member 40, and the entire scanning head 12 moves in the same direction as the expansion and contraction of the cylinder 11 due to the temperature change. Because it expands and contracts,
The operation is similar to that of the above embodiment.

Next, not the pickup lens 27,
An example in which the aperture 28 is connected to the scanning head 12 by a connecting member is shown in FIG. In this embodiment, the connecting member 38
Is provided inside the scanning head 12 in parallel with the cylinder 11, but is fixed to the main body of the scanning head 12 on the same side as the free end of the cylinder 11 (right side in FIG. 4), contrary to the above embodiment. , Holding the aperture 28 at the left free end.

The operation of the present embodiment during image reading will be described with reference to FIG. The light from the document 10 focused by the pickup lens 27 forms an image on the surface of the aperture 28, but since the pickup lens 27 is fixed to the scanning head 12, the position of the document 10 moves to the right due to temperature change. When moved, the image of the pixel to be read formed by the pickup lens 27 moves to the left on the opposite side of the aperture 28. In this embodiment, the expansion and contraction of the connecting member 38 moves the aperture 28 in the direction opposite to the moving direction of the document, so that the aperture of the aperture 28 moves following the image of the pixel to be read. Therefore, also in the present embodiment, the pixel at the correct position can always be read regardless of the temperature change.

[0029]

According to the plate-making input scanner of the present invention,
The movement of the document and the movement of the pixel to be read due to the expansion and contraction of the cylinder due to the temperature change are compensated by the expansion and contraction of the connecting member. Therefore, it is possible to prevent the distortion of the read image due to the temperature change around the scanner. Therefore, no distortion occurs in the recorded image or the displayed image even in the output means. Further, when the output means is an output scanner, when a plurality of times of scanning (single color separation or two-color separation) is performed, the "deviation" of the register mark for each color plate caused by the difference in temperature at each time is prevented. Therefore, it becomes possible to accurately register the pattern.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram around a scanning head of a plate-making input scanner that is an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between an irradiation range of irradiation light and a movement amount of a reading target pixel.

FIG. 3 is a schematic configuration diagram around a scanning head of an input scanner for plate making which is a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram around a scanning head of an input scanner for plate making which is a third embodiment of the present invention.

FIG. 5 is an explanatory diagram showing the relationship between the movement of the pixel to be read and the movement of the aperture in the third embodiment.

FIG. 6 is a schematic configuration diagram of a plate-making input scanner according to the embodiment.

FIG. 7 is a block diagram showing a plate making process including an input scanner.

FIG. 8 is an explanatory diagram showing distortion of a color separation plate (pattern).

FIG. 9 is a plan view showing the relationship between an image created by a scanner and a register mark.

[Explanation of symbols]

10 ... manuscript 11 ... cylinder 12 ... Scanning head 13 ... Mount section 14 ... Main rotary encoder 15 ... Feed screw 16 ... Lateral feed motor 17 ... Reducer 18 ... Encoder 19 ... Raypipe 23 ... Half nut (running body) 24 ... Irradiation light 25, 38, 40 ... Connecting member 26 ... Mounting portion 27 ... Pickup lens 28 ... Aperture 30, 32 ... Selective reflector 34 ... Total reflector 31, 33, 35 ... Photoelectric conversion unit

Claims (2)

[Claims] 1. A document, which is rotatably held by a scanner main body only at one end thereof and has a cylinder on which a document is mounted, and a scanning head which is moved on the scanner main body in parallel with a rotation axis of the cylinder. In a plate-making input scanner for giving a color plate signal obtained by reading to an output means for recording or display, (a-1) one of connecting members arranged substantially parallel to a cylinder at a fixed position of a scanning head. Is fixed, and (b-1) the other end of the connecting member is made to hold a pixel reading unit for reading a minute area of the document, and (c) the connecting member is the thermal expansion material of the cylinder. An input scanner for plate making, which is made of a material having a coefficient of thermal expansion equal to or higher than the coefficient. 2. (a-1) and (b- in claim 1)
Instead of 1), (a-2) one end of a connecting member arranged substantially parallel to the cylinder is fixed to a traveling body for moving the scanning head, and (b-2) the other of the connecting members. An input scanner for plate making, characterized in that a scanning head is held at the end of the.