JPH0716937U - Image output device - Google Patents

Abstract

(57) [Summary] [Purpose] Stable image output is obtained by eliminating poor adhesion. [Structure] This device is a device for obtaining an image output by irradiating a laser beam modulated according to an image signal to a base sheet 2 and an oversheet 3 which are overlapped and held, and a focus adjustment stage having an objective lens 17. 18, a pressure means 20 is provided via a biasing means 19. The pressurizing means 20 includes a plurality of air bearings 21a, 21b,
21c, and an overseat 3 by an air pressure source
Blow air against. The urging means 19 urges the pressing means 20 toward the overseat 3 side,
Presses the oversheet with the air pressure blown out. Since the pressing means 20 presses the oversheet 3 against the base sheet 2 in accordance with the scanning of the laser beam, it is possible to prevent poor adhesion between the two sheets.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an image output apparatus that holds a base sheet and an oversheet in an overlapping manner and outputs an image by scanning exposure with a laser beam.

[0002]

[Prior art]

 Generally, when performing color proofing of multi-color printed matter, a proofing machine having the same configuration as the printing machine is used. In this case, accurate color calibration can be performed, but the calibration machine itself is large and the working time is long. For this reason, recently, an image output apparatus has been developed which directly obtains a multicolor printing sample from an image information created by a scanner or a CEPS (Color Electronic Press System: color electronic plate making system) without using a proof machine ( Approval digital color proofing system manufactured by Kodak).

In this image output device, an oversheet serving as a coloring material is superposed on a base sheet, and the oversheet is exposed by a laser beam modulated according to image information, and the coloring material of the oversheet is thermally sublimated or melted. Is transferred to the base sheet to obtain a color proof (multicolor sample) image. This equipment is a scanning drum in which an oversheet and a base sheet are overlapped and wound, and an oversheet on the rotating drum is exposed with a laser beam that is modulated according to image information to transfer color materials to the base sheet. And a section.

A large number of suction holes are provided on the outer peripheral surface of the rotary drum, and some of the suction holes are used to suck the base sheet. After adsorbing the base sheet, the oversheet is adsorbed in the adsorption holes outside the adsorption holes for adsorbing the base sheet. Therefore, the overseat is set slightly larger than the size of the base sheet.

[0005]

[Problems to be solved by the device]

 The image output device using the rotating drum described above has a problem in that the sheet receives a centrifugal force due to the rotation of the drum, and the sheet is lifted from the drum. Especially when the size of the sheet is large, the central part is less likely to be adsorbed, so that the problem of floating becomes significant.

Further, in the image output device for color calibration, the oversheet is heated by a laser beam, and the color material is transferred to the base sheet by sublimation or heat melting. However, in the process of this thermal sublimation or thermal melting, the generated gas is generated between the base sheet and the oversheet, and the vapor pressure between both sheets increases, so that the sheet is locally lifted. May be generated.

When the sheet is lifted as described above, the adhesion between the oversheet and the base sheet is hindered, so that the transfer position accuracy of the color material is deteriorated, and, for example, a color shift occurs in a multicolor printed matter. The problem occurs. An object of the present invention is to stably bring the oversheet and the base sheet into close contact with each other and prevent the sheet from rising, so that stable image output can be obtained.

[0008]

[Means for Solving the Problems]

 The image output device according to the present invention includes a sheet holding means for holding an oversheet on a base sheet, and a laser beam that moves relative to the base sheet and the oversheet held by the sheet holding means. The apparatus is provided with an exposing means for performing scanning exposure, and the pressing means locally pressurizes the base sheet and the over sheet held by the sheet holding means by air pressure, and the pressing means for the sheet holding means. Urging means for urging.

[0009]

[Action]

 In the image output device according to the present invention, the base sheet and the oversheet held by the sheet holding means are locally pressed against the sheet holding means by the air pressure of the pressing means. Since the pressing means is biased toward the sheet holding means by the biasing means, it is always in a position where the sheet can be pressed. Here, the pressing means is biased toward the sheet holding means by the biasing means, but since air is ejected from the pressing means, the pressing means presses the sheet in a non-contact manner.

[0010]

【Example】

 FIG. 1 shows a main part of an image output apparatus in which an embodiment of the present invention is adopted. This image output device moves in the axial direction (sub-scanning direction) of the rotating drum 1 that holds the base sheet 2 and the oversheet 3 by suction, and scans and exposes the oversheet 3 with a laser beam. And an exposure head unit 4 for performing. Furthermore, the image output device includes a main scanning control device 5 that controls rotation of the rotary drum 1 (control in the main scanning direction), and a sub-scanning control device 6 that controls the exposure head unit 4 in the sub-scanning direction. It has a raster engine 8 for converting the image data processed by the workstation 7 into raster data, and an exposure control device 9 for controlling the exposure of the exposure head unit 4 by the laser beam based on the raster data from the raster engine 8. . The workstation 7 also controls the above-mentioned units.

FIG. 2A shows an outline of a laser optical system which is a main part of the exposure head unit 4. The laser optical system has a semiconductor laser array 10. Each element of the semiconductor laser array 10 is composed of a semiconductor laser 11 and a collimator lens 12, as shown in FIG. A field lens 13 is arranged close to the semiconductor laser array 10. The field lens 13 collects the laser beam from the semiconductor laser array 10 and projects it onto the reduction lens 14. The laser beam which is once projected on the intermediate image by the reduction lens 14 is projected on the imaging lens 16 via the mirror 15. The laser beam projected from the imaging lens 16 enters the objective lens 17 and is focused by the objective lens 17 to form a beam spot on the oversheet 3. The objective lens 17 is supported by the focus adjustment stage 18. The focus adjusting stage 18 is constituted by a motor 38, a ball screw 37, and a slide rail (not shown) so as to be movable in a direction in which it comes in contact with and separates from the peripheral surface of the rotary drum 1. Adjust the focus. The focus adjusting stage 18 is supported by a pressurizing means 20 for pneumatically pressurizing the overseat 3 via a biasing means 19.

FIG. 3 shows details of the biasing means 19 and the pressurizing means 20. The pressurizing means 20 is composed of a support member 22 and air bearings 21a, 21b, 21c, and the air bearings 21a, 21b, 21c are collectively arranged on the support member 22 in series in the circumferential direction of the rotary drum 1. It is supported. FIG. 5 is a schematic plan view showing the arrangement of the air bearings 21a, 21b, and 21c. As shown in the figure, the air bearings 21a, 21b, 21c are arranged in series in the rotation direction (main scanning direction) of the rotary drum. Communication holes 22a, 22b, 22c are formed in the central portions of the air bearings 21a, 21b, 21c, and the overseat 3 is irradiated with the laser beam through the communication holes 22b. Further, each of the air bearings 21a, 21b, 21c is provided with four air outlets 23a, 23b, 23c. In this embodiment, the air outlets 23a and 23c are arranged at the four corners of the air bearings 23a and 23c, respectively, and the air outlets 23b are arranged such that the upper two of them are arranged at the upper corners of the air bearing 23b and the lower two thereof. The individual pieces are arranged directly below the communication holes 22b. This is to prevent the oversheet 3 from being lifted immediately after being irradiated with the laser beam spot. The air outlets 23a, 23b, 23c of the air bearings 21a, 21b, 21c are connected to the air pressure source 24 via precision pressure reducing valves 25, 26, 27, 28 as shown in FIG. . Specifically, the precision pressure reducing valve 25 is communicated with the lower two air outlets 23b, the precision pressure reducing valve 26 is communicated with the upper two air outlets 23b, and the precision pressure reducing valve 27 is connected with the air outlet 23b. Two lower 23a and two upper air outlets 23c communicate with each other, and the precision pressure reducing valves 28 respectively communicate with two upper air outlets 23a and two lower air outlets 23c. . Since the pressure from the air pressure source 24 is divided through the precision pressure reducing valves 25, 26, 27, 28, the precision pressure reducing valves 25, 26, 27, 28 are substantially independent of each other. Work as a pressure source.

FIG. 7 is a view showing a part of the air bearing 21a. The air outlet 23a of the air bearing 21a is connected to each precision pressure reducing valve 28 via an air communication hole 29 in the air bearing 21a. The air blown out from the air outlet 23 a presses the oversheet 3 to bring it into close contact with the base sheet 2. The other air bearings 21b and 21c have the same structure.

The biasing means 19 will be described with reference to FIGS. 3 and 4. Note that FIG. 4 is a detailed view of the biasing means 19. The urging means 19 is fitted to the bearing 31 provided on the support member 22, the sliding shaft 30 fitted to the bearing 31 and one end of which is fixedly mounted on the focus adjusting stage 18, and the sliding shaft 30. Mounted spring 32. The spring 32 urges the support member 22 in a direction in which the support member 22 is separated from the focus adjustment stage 18 (in other words, a direction in which the pressing means 20 is pressed against the rotary drum 1). Further, the sliding shaft 30 is provided with a retaining portion 33 to prevent the support member 22 from falling off the sliding shaft 30. With the above structure, the pressing means 20 slides along the sliding shaft 30 against the bias of the spring 32. Since the biasing means 19 is configured as described above, in addition to the function of biasing the pressurizing means 20, it also has the function of absorbing the vibration transmitted from the pressurizing means 20 to the focus adjustment stage 18. Have.

The focus adjustment stage 18 is provided with a gap sensor 34 as shown in FIG. The gap sensor 34 is a sensor for measuring the distance between the support member 22 and the focus adjustment stage 18, and is a known ultrasonic sensor. The signal from the gap sensor 34 is input to the motor control means 36 for controlling the motor 38 via the low pass filter 35.

Next, the operation of the image output apparatus will be described with reference to FIG. FIG. 8 is a flowchart showing an image output process of the image output apparatus. First, in step S1, each part is initialized. Here, for example, it is checked whether the exposure head unit 4 has returned to the origin, and if it is not at the origin, it is returned to the origin. Here, the return of the exposure head unit 4 to the origin means that the motor 38 drives the ball screw 37 to retract the pressing means 20 in the Y0 direction, as shown in FIG. That is, the exposure head unit 4 is retracted in the X0 direction at one end in the sub-scanning direction. By this return to the origin, the pressing means 20 of the exposure head unit 4 is retracted away from the rotary drum 1. Then, in step S2, the base sheet is loaded on the rotary drum 1. Various devices have been proposed for loading the base sheet, which are disclosed in, for example, Japanese Patent Application No. 5-121097 filed by the present applicant, and therefore detailed description thereof will be omitted here. Then, in step S3, the oversheet is stacked on the rotary drum 1 and loaded on the base sheet.

When the loading of both sheets is completed, drawing is started in step S4. At this time, the exposure head unit 4 first moves in the sub-scanning direction and is positioned at the drawing start position. After that, the air is blown from the pressurizing means 20, and the motor 38 is controlled to move the pressurizing means 20 onto the rotary drum 1, that is, the overseat 3. When the pressing means 20 moves onto the overseat 3, the pressing means 20 floats against the spring force of the urging means 19 by the force of the air pressure blown onto the overseat 3. That is, as shown in FIG. 7, each air bearing is a self-throttled air bearing, and a throttle is automatically formed between the surface of the overseat 3 and each air outlet. About 20 μm floats on the oversheet 3. The air pressure is appropriately set according to the spring pressure of the biasing means 19. When the exposure head unit 4 is located at the predetermined drawing start position as described above, the rotary drum 1 is rotated to start drawing. As described above, the pressurizing means 20 floats above the oversheet 3 by the air pressure, so that the oversheet 3 is pressed in close contact with the base sheet 2 in a non-contact manner. Therefore, when the laser beam spot is irradiated, drawing is performed while the sheets in the irradiated portion are appropriately adhered to each other, and it is possible to eliminate drawing defects due to floating of each sheet. Further, the vibration of the pressing means 20 due to the minute unevenness of each sheet or the rotary drum is not transmitted to the objective lens 17 or the like by the biasing means 19.

The distance between the support member 22 and the focus adjustment stage 18 which varies according to the vibration of the pressurizing means 20 is detected by the gap sensor 34 and fed back to the motor control means 36. Thereby, the focal length of the objective lens 17 can be kept constant. The low-pass filter 35 is provided for the purpose of cutting minute noise.

When the drawing is completed, the exposure head unit 4 is returned to the origin again in step S5, and then the oversheet is unloaded in step S6. In the normal color calibration, since the calibration with four colors is general, it is determined in step S7 whether or not the drawing for all four colors has been completed. If not completed, steps S3 to S6 are repeated for the next color for which drawing has not been completed. When the drawing is completed for all the colors, the base sheet is unloaded in step S8 and the process is completed.

Next, the operation of the pressing means 20 due to the unevenness on the rotary drum 1 will be described. FIG. 9 is a diagram showing an example of the case where relatively large unevenness exists on the rotary drum 1. The loading of the sheet in this figure is a method of fixing the end portion of the sheet to the blade 39, and is disclosed in, for example, Japanese Utility Model Application Laid-Open No. 3-38838, filed by the present applicant. As described above, if there is a large unevenness on the rotating drum 1 as compared with the flying height of the air bearing of 10 to 20 μm, when the air bearing approaches the above unevenness, it suddenly tries to approach the rotating drum 1 side. That is, in FIG. 9, when the upper air outlet 23a of the air bearing 21a reaches the concave portion of the blade 39, the air outflow amount from the air outlet 23a temporarily increases. As a result, the air pressure is reduced and the levitation force of the air bearing 21a with respect to the overseat 3 is sharply reduced, so that the air bearing tends to approach the rotary drum 1 side. In the worst case, the air bearing may come into contact with the overseat due to the abrupt approaching of the air bearing, resulting in damage to the overseat.

In order to prevent such a situation, in this embodiment, a plurality of air bearings 21a, 21b, 21c are fixedly supported by one support member 22. Thus, for example, even if the air bearing 21a tries to approach the rotary drum 1 side, the air bearing 21a and the rotary drum 1 can be prevented from approaching abnormally by being supported by the other air bearings 21b and 21c. Then, the air bearings 21a, 21b, 21c can successively ride over the recess while supporting each other. By thus supporting a plurality of air bearings collectively by one supporting member, it is possible to prevent a single air bearing from approaching or contacting the rotating drum. Further, in this embodiment, since the air pressure source 24 is divided by the precision pressure reducing valves 25 to 28, the risk that the air pressures of the air bearings 21a, 21b, 21c decrease will be dispersed. As a result, even if the air pressure of one air bearing decreases, it does not affect other air bearings.

[Other Embodiments] (a) In this embodiment, three air bearings are arranged in series, but other numbers may be arranged. Further, the arrangement state may be changed. (B) In this embodiment, the pressing means is attached to the focus adjustment stage that supports the objective lens, but it may be provided separately.

(C) In the present embodiment, the image output device of the rotary drum type is taken as an example, but the present invention can be applied to the image output device of the flat table type.

[0024]

[Effect of device]

 The image output device of the present invention can press the sheet in a non-contact manner locally, and does not cause drawing defects due to poor contact, so that stable image output can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of an image output apparatus to which an embodiment of the present invention is applied.

FIG. 2 is a perspective view showing a main part constituting an optical system of an exposure head section of the present apparatus.

FIG. 3 is a cross-sectional view showing a pressurizing unit and a biasing unit of the present device.

FIG. 4 is a sectional view showing the biasing means.

FIG. 5 is an explanatory view showing an arrangement of air bearings that constitute the pressurizing means.

FIG. 6 is an explanatory view showing pneumatic piping of an air bearing.

FIG. 7 is a partially enlarged perspective view of an air bearing.

FIG. 8 is a flowchart showing an image output process of this apparatus.

FIG. 9 is a diagram for explaining the relationship between the unevenness of the rotary drum and the operation of the air bearing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotating drum 2 base sheet 3 over sheet 4 exposure head section 19 biasing means 20 pressurizing means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Kosuke Fukui 1 465, Kuze Tsukiyama-cho, Minami-ku, Kyoto 1 Dainichihon Screen Mfg. Co., Ltd., Kuze Factory

Claims (1)

[Scope of utility model registration request] 1. A sheet holding means for holding an oversheet overlaid on a base sheet, and an exposure for performing scanning exposure with a laser beam by moving relative to the base sheet and the oversheet held by the sheet holding means. An image output device having means for pressing the base sheet and the oversheet locally held by the sheet holding means by air pressure, and urging the pressing means against the sheet holding means. An image output device comprising: a biasing unit.