JPH02226112A - Optical scanning device - Google Patents

Abstract

PURPOSE:To prevent an image formation position from shifting owing to surface inclination by using plural beams which are incident on a rotary polygon mirror at the same beam incidence position and imaged on a scanned body at different image formation position in a main scanning direction, and emitting one of the beams selec tively according to the surface tilt angle of each surface. CONSTITUTION:A beam irradiation scanning line formed on the scanned body by main scanning is at a certain angle to the main scanning direction because of the movement of the scanned body in a subscanning direction. Here, one of the beams is emitted selectively according to the surface tilt angle of each surface of the rotary polygon mirror 270 and while the angle of incidence on the rotary polygon mirror 270 is varied, the angle of incidence is varied by a movable mirror 262 to set an image formation position within the range of the angle of incidence, so that an image formation line can be adjusted within the width in the subscanning direction. Namely, the angle of incidence for compensating the dislocation in the image formation position due to the surface inclination of the rotary polygon mirror 270 is set for each surface of the rotary polygon mirror 270 corresponding to the dislocation in the image forma tion position. Consequently, the dislocation in the image formation position is eliminat ed to obtain an image having no density irregularity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical scanning device that scans a beam of light on a scanned object by reflecting the beam on a rotating polygon mirror.

This conventional technology] In an optical scanning device that uses a rotating polygon mirror and beam reflection,
It is often used to record an image on a photosensitive material that is being scanned. A beam corresponding to the image is emitted toward a rotating polygon mirror, and the polygon mirror is rotated to direct the beam toward the photosensitive material. The photosensitive material is subjected to image exposure by performing reflective scanning (main scanning) and simultaneously moving the photosensitive material in a direction intersecting the scanning direction (sub-scanning).

[Problem to be solved by the invention]

When performing exposure while moving the photosensitive material in the sub-scanning direction,
As mentioned above, in main scanning, one scanning line is formed by the rotational reflection of one surface of a rotating polygon mirror, but each of these surfaces has a different surface tilt, and each scanning line is formed by the different surface tilt of each surface. The line image formation interval shifts, causing image density fluctuations, resulting in density unevenness, which significantly impairs image quality. Since this density deviation occurs with an image formation position shift of about 0.34-degrees on the photosensitive material, eliminating this surface tilt requires extremely high-precision processing, which increases costs. Further, normally, a surface tilt correction optical system is used, but this optical system is also expensive, and the cost also increases.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and to provide an optical scanning device that can uniformly scan an object by preventing the image formation position from shifting due to the surface tilt of a rotating polygon mirror. It's about doing.

[Means and effects for solving the problem] The above object of the present invention is to provide an optical system that performs main scanning intersecting the sub-scanning direction by beam reflection by a rotating polygon mirror on a scanned object moving in the sub-scanning direction. The scanning device includes a plurality of beams having the same beam incidence position on the rotating polygon mirror and different beam imaging positions on the scanned object in the main scanning direction, and wherein One of the plurality of beams depending on the deflection angle.
This is accomplished by an optical scanning device that selectively uses two beam emissions.

Furthermore, on the object to be scanned moving in the sub-scanning direction as mentioned above! Koda = An optical scanning device that performs main scanning intersecting the sub-scanning direction by reflecting a beam on a mirror, which scans the scanned object by keeping the beam incident position on the rotating polygon mirror constant and making the incident angle variable. This can also be achieved by having a beam changing means for changing the beam imaging position on the body in the main scanning direction, and setting the incident angle according to the inclination angle of each surface of the rotating polygon mirror.

That is, because the object to be scanned moves in the sub-scanning direction, the beam irradiation scanning line on the object to be scanned during main scanning forms a certain angle .theta. with respect to the main scanning direction, as shown in FIG.

Therefore, as described above, depending on the angle of inclination of each surface of the rotating polygon mirror, one beam emission from the plurality of beams is selected and the incident angle to the rotating polygon mirror is changed, or the angle of incidence on the rotating polygon mirror is changed. By changing the angle of incidence on the rotating polygon mirror, the imaging position can be set arbitrarily within the range of this angle of incidence.
The imaging line can be adjusted within the ray y in the sub-scanning direction.

Then, by setting the incident angle for each surface of the rotating polygon mirror to compensate for the deviation of the image forming position due to the surface tilt of the rotating polygon mirror, the image forming position deviation is eliminated and the concentration A good image without unevenness can be obtained.

Photosensitive materials (subjects to be scanned) that can be used in the present invention include:
Any material may be used as long as a latent image obtained by imagewise exposure can be subjected to processing such as development, transfer, and fixation to obtain a visible image.

For example, black and white photographic materials using silver halide,
There are photosensitive materials for ray, photosensitive materials for plate making, conventional color photosensitive materials (negative film, reversal film, color photographic paper, etc.), color diffusion transfer photosensitive materials, heat developable photosensitive materials, and photosensitive pressure sensitive materials. .

[Embodiment]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the optical scanning device according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of an image forming apparatus to which an embodiment of the apparatus of the present invention is applied.

Inside the housing 12 constituting the image forming apparatus, there is a photosensitive material supply section 13 that stores the photosensitive material A, an image reading section 15 that reads image information carried on the document S, and a latent image formed on the photosensitive material A. Exposure if6, water application section 17 that applies water to photosensitive material A, image receiving paper supply section 41 that stores image receiving paper C, overlapping section 19 that overlaps image receiving paper C on photosensitive material A, photosensitive material A A heat development transfer section 21 that heats the image-receiving paper C, and a peeling section 23 that separates the image-receiving paper C from the photosensitive material A are provided, respectively.

A transparent document support glass plate 14 on which the document S is placed is arranged on the upper surface of the housing 12. Below the document support glass plate 14, an image reading device 200, an image processing device 250, and an exposure device 300 are installed. The image reading section 15 consists of
is placed.

Further, a standard white plate 302 is provided near the document support glass plate 14 so as to be exposed to the light source 18, while the photosensitive material supply unit 13 is provided on the left side of the housing 12 and is light-tight. is maintained. This photosensitive material supply 6
13: A removable photosensitive material magazine 54 in which the photosensitive material A is wound up and stored is loaded.

The photosensitive material A has a photosensitive silver halide, a binder, a dye-providing substance, and a reducing agent on a support.

The photosensitive material supply section 13 has roller pairs 56a to 56d for conveying the photosensitive material A from the magazine 54 to the exposure section 16. In this case, roller pair 56a.

A cutter 58 for cutting the photosensitive material A into predetermined lengths is provided between the cutters 56b. Further, in the partition wall 22 surrounding the image reading section 15, an exposure opening 34 related to the exposure section 16 of the photosensitive material A is defined in a portion through which the optical axis 32 from the image reading section 15 passes. A shutter device 35 and a shutter control device 36 are arranged in the opening 34 .

The exposure table 6 is disposed between the roller pair 56C and 56d.
0 faces the exposure opening 34.

In front of the exposure section 16 (hereinafter, "front" refers to the downstream side with respect to the traveling direction of the photosensitive material, etc.) is provided with a conveyance path consisting of a pair of rollers 56e and a guide plate.

The exposure section 16 performs imagewise exposure on the photosensitive material A to form a latent image, and the photosensitive material A on which the latent image is formed is conveyed to the water application section 17 via the conveyance path.

The water application section 17 is for facilitating the transfer of the latent image formed on the photosensitive material A, and is composed of a pair of rollers 56f1, a pair of squeeze rollers 176, a guide plate 172, and a water tank 174. Then, the water tank 174 is filled with water, and the photosensitive material A is transported while being immersed in the water.

The photosensitive material A coated with water is squeezed by a pair of squeeze rollers 176.
It is conveyed to the overlapping section 19 by.

On the other hand, on the right side of the housing 12, a receiving paper supply section 41 for supplying the receiving paper C is provided. The image receiving paper supply section 4
1 is a receiving paper magazine 43 that stores rolled receiving paper C;
is loaded.

A dye fixing material containing a mordant is applied to the image forming surface of the image receiving paper C.

The image receiving paper C in the magazine 43 is fed out by a pair of rollers 56h, and cut into a predetermined length by a cutter 44 disposed in front of the pair of rollers 56h.

The cut image-receiving paper C is conveyed to the overlapping section 19 by a pair of rollers 56i.

In front of the overlapping part 19, the overlapping photosensitive materials A
A heating development transfer section 21 is provided which heats the image receiving paper C, develops the latent image on the photosensitive material A, and transfers it onto the image receiving paper C.

The heat development transfer section 21 is surrounded by a heat insulating partition wall 62, and is wrapped around a hollow cylindrical heating drum 74 containing a halogen lamp 72 at an angle of about 270° around the outer peripheral surface of the heating drum 74. (The length of the winding is 240mm.
), endless belt 8 as pressing means supported by four belt support rollers 76, 77, 78, 80
4, and a bonding roller 85 that comes into contact with the circumferential surface of the heating drum 74 and bonds the photosensitive material A and the image-receiving paper C, which are conveyed to the heat development transfer section 21, before heating. Heat paper C in a stacked state. By this heating, the latent image on the photosensitive material A is developed and transferred onto the image receiving paper C to develop color.

The surface of the heating drum 740 is coated with Teflon, and is further heated to about 90° C. by a halogen lamp 72.

Furthermore, the endless belt 84 is made of aromatic polyamide fiber (
For example, it has a structure in which a heat-resistant material such as Kevlar or Nomex (both registered trademarks of DuPont) is coated with carbon-containing silicone rubber, and is electrically conductive. With such a configuration, the heating drum 74
Generation of static electricity due to friction between the endless belt 84 or the photosensitive material A is prevented.

When the photosensitive material A is heated in the thermal development transfer section 21 (between the heating drum 74 and the endless belt 84) while being overlapped with the image receiving paper C, a mobile dye is released, and at the same time, this dye is transferred to the image receiving paper. The image is transferred to the dye fixing layer C to obtain an image.

A peeling section 23 is provided within the partition wall 62, and the peeling section 23 includes a first peeling claw 232 for peeling the photosensitive material A from the image receiving paper C, and a first peeling claw 232 for peeling the image receiving paper C from the heating drum 74. It consists of two peeling claws 234 and a roller 56j that discharges the image receiving paper C to the outside of the partition wall 62.

In front of one side of the heat development transfer section 21, there is a waste tray 118 for discarding the heated photosensitive material A peeled from the image receiving paper C by the peeling claw 232, and a roller pair 56k for supplying the photosensitive material into the waste tray 118. is provided. The waste tray 118 is provided below the heat development transfer section 21 .

In addition, in front of the other side of the heat development transfer section 21, there is a take-out tray 120 for storing the heated image receiving paper C and a pair of rollers 561.56m, 5 for conveying the heated image-receiving paper C to the take-out tray 120.
5n is provided, and the image-receiving paper C on which the image has been transferred is led out to the take-out tray 120.

Further, a color density detection unit 124 for detecting the color density of the image on the image receiving paper C is arranged between the pair of rollers 56m and 56n. The color density detection unit 124 includes an illumination device 126 that illuminates the image surface of the image receiving paper C, and a color photosensor 128 that receives reflected light from the image receiving paper C due to this illumination.

The apparatus further includes a color density control unit 1 connected to the imaging lens/filter unit assembly 30 and the photosensor 128 and disposed at a suitable location within the housing 12.
50, the color density control unit 150, the photosensitive material supply section 13, the image reading section 15, the drive system for the image reading section 15 (not shown), the receiving paper supply section 41, the cutter 44, 58, the shutter control device 36, A system control device (not shown) is provided which is connected to the water application section 17, the heat development transfer section 21, and the peeling section 23 and controls the entire apparatus.

FIG. 2 shows an image reading device 20 representing an optical scanning device of the present invention.
FIG. 2 is a schematic diagram showing an exposure processing path from 0 to an image processing device 250 and an exposure device 30G.

That is, the image reading device 200 uses the original supporting glass plate 14.
The light source 18, the mirror 20a, the imaging lens/filter unit assembly 30, which integrally scans the entire surface of CCD sensor 2
20, which are surrounded by a partition wall 22 and optically isolated from other parts.

Next, in the image processing device 250, the analog/digital conversion circuit 222 converts the read signal from the CCD sensor 220 into a digital signal. Next, assembly 30 and C
The deterioration of the spatial frequency response that occurs in the CD sensor 220 etc. is corrected by the contour enhancement circuit 224, the signal from the color density control unit 150 is input, and the exposure amount of each pixel is determined by the color correction calculation circuit 226. An exposure control circuit 228 controls the exposure amount of each color.

In the exposure apparatus 300, three semiconductor lasers 252°254
．． 256, a polygon mirror 270 (rotating polygon mirror), an fθ lens 280, and a mirror 290.

The semiconductor lasers 252, 254, and 256 are arranged so that the laser beams are irradiated parallel to the rotation plane of the polygon mirror 270, and are irradiated to a point on the reflection plane of the polygon mirror 270 at different incident angles.

The image light irradiated from the semiconductor radars 252, 254, and 256 is reflected and moved in the main scanning direction by the reflecting surface of the polygon mirror 270 as it rotates around the axis 271, and is focused by the fθ lens 280, and is reflected by the mirror 270. It is reflected at 290 and scans and exposes the photosensitive material A.

Arrangement angle Δθ(
deg) by setting the following parameters in advance (1)
Installed by the ceremony.

Photosensitive material movement speed: v (Q/S) Polygon mirror rotation speed: r (Rotation/S) Desired image formation movement range: d (mm) Image formation movement range d is the maximum amount of surface tilt of each reflective surface of the polygon mirror It is set within the range that compensates for.

FIG. 3 is a diagram showing an example of an image formation position on a photosensitive material.

Imaging scanning lines, M, and N are semiconductor lasers 252.
It corresponds to 254.256. This semiconductor laser 25
2.254.256 is the polygon mirror 27 as described above.
Since these semiconductor lasers are aligned parallel to the rotation plane of 0, if these semiconductor lasers are irradiated at the same timing, the imaging positions O9P and Q will be formed at intervals of Xt and Xi in the main scanning direction X perpendicular to the sub-scanning direction Y, respectively. becomes. Here, by setting the irradiation timing of the semiconductor laser 252 to a timing at which the imaging position is delayed by the interval X, the imaging position ○ can be moved to the imaging position S, and the irradiation timing of the semiconductor laser 256 is By timing the position to be earlier by the interval x1, the imaging position Q can be moved to the imaging position R.

By doing the above, it is possible to set the imaging setting range y from the imaging position S to the imaging position R.

For example, if the desired imaging scanning line position for a certain reflective surface of the polygon mirror 270 is the imaging scanning line shown in the figure, this is the closest to the imaging scanning line N, so the semiconductor laser 256 in advance and set it to emit light at a timing that is earlier by the interval X7.

By performing this treatment on each reflective surface of the polygon mirror 270, it is possible to minimize image formation deviation due to surface tilt.

FIG. 4 is a schematic diagram showing another embodiment of the optical scanning device of the present invention.

This embodiment uses the semiconductor laser 252.25 shown in FIG.
4.256 as one semiconductor laser 260 and movable mirror 2
62.

The semiconductor radar 260 is fixed, and the movable mirror 26
2 is restricted in movement to a preset locus (for example, a circular arc) on the rotation plane of the polygon mirror 270.

The movement of the movable mirror 262 along this trajectory changes the incident angle e without changing the incident position of the image light from the semiconductor laser 260 onto the polygon mirror 270.

In other words, the incident angle can be continuously changed by moving the movable mirror 262 along this trajectory, so that the image beam from the semiconductor laser 260 is directed to each reflective surface of the polygon mirror 270 to the optimal imaging position on the photosensitive material. It is possible to set the incident angle to an angle of incidence that is approximately 100 degrees, and almost eliminate image formation deviation due to surface tilt.

Furthermore, the movable mirror 262 can also be used with a prism, an acousto-optic element, or the like. Furthermore, any device other than a semiconductor laser may be used as long as it can emit a beam capable of expressing image light.

In addition, in the above two embodiments, the semiconductor laser was described with reference to one wavelength, so when performing color image expression, in the embodiment shown in FIG. The embodiment of FIG. 4 requires one semiconductor laser for each wavelength.

〔Effect of the invention〕

According to the present invention, as described above, by using a beam with a variable angle of incidence on the rotating polygon mirror that has different imaging positions in the main scanning direction, the imaging line can be formed with a width in the sub-scanning direction depending on the range of the incident angle. Since the angle of incidence can be adjusted within y, the angle of incidence can be set in advance for each surface of the rotating polygon mirror to compensate for the deviation of the imaging position due to the tilt of the surface of the rotating polygon mirror. It is possible to eliminate the image formation position shift and obtain a good image without density unevenness.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the image forming apparatus, Fig. 2 is a schematic diagram of the optical scanning device, Figs. 3 and 5 are diagrams showing the state of image formation on the photosensitive material, and Fig. 4 is the optical scanning device. FIG. 2 is a schematic configuration diagram showing another embodiment of the . Symbols in the figure: 10... Image forming device 12 - Housing 13
...Photosensitive material supply section 4--Original support glass plate 15--Image reading section 7--Water coating section 18--Light source 9--
...overlapping parts Qa, b, this... mirror 1 - heat development transfer part 22 - partition wall 3 - peeling part 〇 - imaging lens/filter unit assembly 2... Optical axis 36 - Shutter control device l - Image receiving paper supply section 43 - Image receiving paper magazine 4.58 - One cutter - 5
4-...Sensitive material magazines 6a to 56n..., roller pair
6 Misaki...Exposure stand 2-...Halogen lamp
74... Heating drum 6.77.78.80...
Belt support roller 4--endless belt 5--bonding roller 18--disposal tray 12--take-out tray 2
4.-Color density detection unit 126...Lighting device 2
8...Color photo sensor 50-...Color density control unit 00,... Image reading device 220...CCD sensor 222-...Analog/digital conversion circuit 224
- Contour emphasis circuit 226...Color correction calculation circuit 228-Exposure control circuit 250. ...Image processing device 25
2.254, 256.260... semiconductor laser 26
2. Movable mirror 270... Polygon mirror 280.-
・・fθ lens 290・・・・Mirror 300・
- Exposure device V - Photosensitive material movement speed r - Polygon mirror rotation speed d - Desired imaging movement range, L, M, N - Imaging scanning line X - Main scanning direction Y...Sub-scanning direction 0, P, Q
, R, S-・1. Image formation position
−・Image formation setting range

Claims (2)

[Claims] (1) An optical scanning device that performs main scanning across an object to be scanned moving in the sub-scanning direction by beam reflection on a rotating polygon mirror, wherein the beam incidence position on the rotating polygon mirror is It has a plurality of beams that are the same and have different beam imaging positions on the object to be scanned in the main scanning direction, and one of the plurality of beams is emitted according to the angle of inclination of each surface of the rotating polygon mirror. Select the optical scanning device to use. (2) An optical scanning device that performs main scanning across a sub-scanning direction by reflecting a beam on a rotating polygon mirror on a scanned object moving in the sub-scanning direction, the beam incident position on the rotating polygon mirror being The beam changing means changes the beam imaging position on the object to be scanned in the main scanning direction by making the incident angle constant and variable; Optical scanning device to set the angle of incidence.