JP2002131675A - Exposure recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high-quality images free of unevenness by easily regulating the widths to a sub scanning direction of the respective light beams outputted from respective light sources arrayed in the sub-scanning direction with high accuracy. SOLUTION: The near field patterns of the laser beams L outputted from semiconductor lasers 18 are imaged to apertures 24 through collimator lenses 20 and cylindrical lenses 22 and the widths thereof to the sub-scanning direction (arrow Y direction) are regulated by the turning angles of the apertures 24. The laser beams L regulated in the widths are guided through the cylindrical lenses 26 and imaging lenses 28 to a recording film F and the beam spots consisting of the desired recording widths are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure recording apparatus for exposing and recording an image by scanning a recording medium in a main scanning direction and a sub-scanning direction with a light beam.

[0002]

2. Description of the Related Art For example, while a drum having a photosensitive material mounted on an outer peripheral surface is rotated in a main scanning direction, a laser beam modulated according to an image is scanned in a sub-scanning direction orthogonal to the main scanning direction. There is used an exposure recording apparatus which records a two-dimensional image on the photosensitive material.

[0003] In such an exposure recording apparatus, a plurality of light sources are arranged in the sub-scanning direction for the purpose of high-speed recording of a large-sized image, and these light sources are simultaneously driven to perform recording. (Japanese Unexamined Patent Publication No. 7-231)
No. 95). In this case, if the beam diameter of the laser beam output from the adjacent light source varies, a defect such as a streak-like unevenness occurs in a connection portion of a recording range by each light source, or a density unevenness occurs in a recording range of each light source. Will occur.

[0004] As a method of solving such a problem,
In view of the fact that the light quantity distribution in a plane orthogonal to the optical axis of a normal laser beam becomes Gaussian, it is conceivable to control the beam diameter on the photosensitive material by adjusting the light quantity of each laser beam. That is, when an image is exposed and recorded on a photosensitive material having the color development threshold shown in FIG. 1, a spot having a beam diameter a can be formed with a laser beam having a light amount distribution of the characteristic A. Therefore, by adjusting the light amount to obtain a laser beam having the light amount distribution of the characteristic B, a spot having a beam diameter b can be formed.

However, when the light amount of a laser beam having a Gaussian light amount distribution is adjusted as described above, the color forming range slightly changes due to a change in the light amount due to the environmental temperature, the concentration of a developing solution after exposure, and the like. Control them with high precision at all times,
Extremely difficult.

On the other hand, as shown in FIG. 2, there is a laser light source having a characteristic C in which a light amount distribution in one scanning direction is substantially rectangular. As a laser light source capable of obtaining such a light amount distribution, for example, a refractive index guided semiconductor laser can be mentioned. In this case, even if the light amount of the laser beam fluctuates according to the characteristic D due to environmental temperature or the like, or even if the concentration of the developing solution after exposure fluctuates, the light amount distribution is substantially rectangular, The beam diameter c does not change with respect to the direction.

However, in the case of this type of laser light source, there is no variation in the beam diameter c due to a change in the amount of light, but there is variation in the beam diameter c as an individual difference of the light source.
In order to absorb such individual differences, a method of individually adjusting the magnification of the imaging lens provided between the laser light source and the photosensitive material is considered, but the lens configuration and the magnification adjustment mechanism become complicated, There is a disadvantage that the cost increases.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problem, and has been made to reduce the width of each light beam output from each light source arranged in the sub-scanning direction in the sub-scanning direction. It is an object of the present invention to provide an exposure recording apparatus which can easily and accurately adjust and obtain a high-quality image without unevenness.

[0009]

An exposure recording apparatus according to the present invention is an exposure recording apparatus for exposing and recording an image by main-scanning and sub-scanning a recording medium with a light beam. A plurality of light sources that output light beams whose light amount distribution in the sub-scanning direction is substantially rectangular; a first imaging optical system that forms an image of a near-field pattern of the light beams output from each of the light sources; (1) an opening which is arranged at an imaging position of the near-field pattern by the imaging optical system and adjusts the width of the near-field pattern in the sub-scanning direction by rotating about a main scanning direction; And a second imaging optical system that forms the aperture image of the near-field pattern adjusted by the above on the recording medium.

In this case, by rotating each of the apertures arranged at the imaging position of the near-field pattern of each light beam about the main scanning direction as an axis, the substantial aperture width in the sub-scanning direction is adjusted, Thereby, the width of the light beam on the recording medium in the sub-scanning direction can be adjusted.

When the opening is rotated, the width adjustment position of the light beam by each edge portion on both sides in the sub-scanning direction is shifted in the optical axis direction, and the effect of this shift is the effect of the opening image on the recording medium. Appears as a deformation of the shape. Therefore, the rate of increase in the width of the near-field pattern in the sub-scanning direction, which is the allowable amount of the deformation, is defined as n%, and D0 · sin θmax · m ² <ΔZ / n (D0: the width of the opening in the sub-scanning direction, θmax: Maximum rotation angle of the aperture, m: imaging magnification of the second imaging optical system, Δ
Z: distance in the optical axis direction where the width of the near-field pattern in the sub-scanning direction increases by n%) so that the width of the light beam in the sub-scanning direction falls within a predetermined allowable range. Can be adjusted.

[0012]

FIG. 3 and FIG. 4 show a laser recording apparatus 10 to which the exposure recording apparatus of the present invention is applied. The laser recording apparatus 10 records an area-modulated image by irradiating a recording film F (recording medium) mounted on a drum 14 with a plurality of laser beams L emitted from an exposure head 12. It is. Note that a two-dimensional image is formed on the recording film F by moving the exposure head 12 in the sub-scanning direction (arrow Y direction) with respect to the drum 14 rotating in the main scanning direction (arrow X direction). The area-modulated image means that a plurality of pixels are formed on the recording film F by controlling on / off of the laser beam L according to image information, and a predetermined gradation is obtained according to the area occupied by the pixels. Image.

The exposure head 12 is composed of a plurality of light source units 16A to 16N arranged in the sub-scanning direction (the direction of arrow Y). Each of the light source units 16A to 16N includes a semiconductor laser 18 (light source) that outputs a laser beam L modulated according to image information, a collimator lens 20 that collimates the laser beam L, and sub-scanning of the collimated laser beam L. Lens 22 for focusing in the direction (arrow Y direction), an opening 24 disposed at the focal position of the cylindrical lens 22, and a parallel light beam for focusing the laser beam L in the sub-scanning direction (arrow Y direction). And a focusing lens 28 for focusing the laser beam L on the recording film F.

Here, as the semiconductor laser 18, FIG.
As shown in the characteristic C (or D), the broad area laser diode (BL) that outputs the laser beam L whose light amount distribution in the sub-scanning direction (the direction of the arrow Y) is substantially rectangular.
D) can be used.

The collimator lens 20 and the cylindrical lens 22 constitute a first imaging optical system that forms an image of the near-field pattern of the laser beam L output from the semiconductor laser 18 at the position of the opening 24. Further, a cylindrical lens 26 and an imaging lens 28
Constitutes a second imaging optical system that forms the aperture image of the near-field pattern adjusted by the aperture 24 on the recording film F.

FIG. 5 is a diagram showing a detailed configuration of the opening 24. As shown in FIG. Each opening 24 of the light source units 16A to 16N
Are arranged on a common base 30 which is long in the sub-scanning direction (the direction of arrow Y). On the base 30, a positioning table 32
The support frame 34 is fixed via the. A hole 36 formed in the center of the support frame 34 has a main scanning direction (arrow X direction).
An opening member 40 having a rectangular slit 38 for regulating the width of the laser beam L in the sub-scanning direction (the direction of the arrow Y) is attached.

The positioning table 32 supporting the opening member 40 via the support frame 34 has its axis centered in the main scanning direction (the direction of the arrow X).
Is rotatably supported by the base 30 via a shaft member 42 parallel to the shaft. In the positioning table 32, arc-shaped long holes 44a and 44b are formed at symmetrical portions around the shaft member 42. Bolt members 46a, 46b are inserted into these long holes 44a, 44b. Bolt members 46a, 46
b is screwed to the base 30, and by fastening these, the positioning table 32 is fixed to the base 30.

The laser recording apparatus 10 according to the present embodiment is basically configured as described above. Next, the operation and effect thereof will be described.

First, a schematic operation of the laser recording apparatus 10 will be described.

3 and 4, a laser beam L output from a semiconductor laser 18 modulated in accordance with image data is collimated by a collimator lens 20, and then is collimated by a cylindrical lens 22 in the sub-scanning direction (in the direction of arrow Y). ) To form an image of a near-field pattern of the laser beam L on the opening 24.

As shown in FIG. 2, the near-field pattern formed on the aperture 24 has a light quantity distribution substantially rectangular in the sub-scanning direction (the direction of arrow Y). After the beam diameter c (in the direction of the arrow Y) is adjusted by the slit 38 of the aperture member 40, the beam is guided to the cylindrical lens 26. The laser beam L converged by the cylindrical lens 26 in the sub-scanning direction (the direction of the arrow Y) and converted into a parallel light beam is condensed by the imaging lens 28, and an aperture image of the slit 38 is formed on the recording film F.

In this case, the drum 14 on which the recording film F is mounted is rotating in the main scanning direction (the direction of the arrow X), and N laser beams L output from the light source units 16A to 16N are used to simultaneously drive N main drums. A scanning line is formed.
On the other hand, the exposure head 12 moves in the sub-scanning direction (arrow Y direction), and a two-dimensional image is formed on the recording film F by this movement. Since the laser beam L applied to the recording film F has a substantially rectangular light quantity distribution in the sub-scanning direction (the direction of the arrow Y), it is possible to obtain an image without fluctuation due to light quantity fluctuation. .

Since the individual semiconductor lasers 18 have individual differences, the widths of the output laser beams L in the sub-scanning direction (the direction of the arrow Y) are not always the same. Further, it is extremely difficult to design the slits 38 themselves that regulate the width of the laser beam L in the sub-scanning direction (the direction of the arrow Y) in the same manner.

Therefore, in the present embodiment, the above-mentioned disadvantage is solved by configuring the openings 24 constituting each of the light source units 16A to 16N so as to be individually adjustable.

That is, as shown in FIG. 5, the opening member 40 forming the opening 24 is
2 is rotatable. Opening member 4
By rotating 0 around the main scanning direction (arrow X direction), the width of the slit 38 with respect to the laser beam L in the sub scanning direction (arrow Y direction) changes. After adjusting the width for each of the light source units 16A to 16N, the bolts 46a and 46b are fastened to fix the support frame 34. As a result, the width of the laser beam L output from the light source units 16A to 16N and irradiated on the recording film F in the sub-scanning direction (the direction of the arrow Y) can be set to be the same regardless of the individual difference of the semiconductor laser 18. it can.

Here, when the width of the laser beam L is adjusted by rotating the opening member 40, as shown in FIG. 6, the slit 3 in the sub-scanning direction (the direction of arrow Y) is used.
8 is formed on the recording film F because the laser beam L shaped by one edge 48a and the laser beam L shaped by the other edge 48b have different shaping positions in the optical axis direction (arrow Z direction). The resulting beam spot shape becomes asymmetric with respect to the sub-scanning direction (the arrow Y direction).

Therefore, in order to keep the deformation of the beam spot shape within an allowable range, the design parameters of the exposure head 12 are set according to the following equations. That is, the width of the slit 38 in the sub-scanning direction (the direction of the arrow Y) is D
0, the maximum rotation angle of the aperture member 40 is θmax, the imaging magnification of the cylindrical lens 26 and the imaging lens 28 is m, and the sub-scanning direction of the near field pattern at the position displaced by the distance ΔZ in the optical axis direction Z (arrow Y). The width D0, the maximum rotation angle θmax, and the imaging magnification m so that D0 · sin θmax · m ² <ΔZ / n, where n is the rate of increase of the width of the
Is set, a beam spot having a deformation ratio of less than n% can be formed on the recording film F.

In the case of a broad area laser diode, it is generally known that the increase rate of the width of the near-field pattern in the sub-scanning direction (arrow Y direction) is about 10%. Therefore, in this case, it is desirable to set the design parameters of the exposure head 12 such that D0 · sin θmax · m ² <ΔZ / 10.

[0029]

As described above, according to the exposure recording apparatus of the present invention, each opening disposed at the image forming position of the near field pattern of each light beam is rotated about the main scanning direction. Thereby, the substantial opening width in the sub-scanning direction can be adjusted, and thereby, the width of the light beam on the recording medium in the sub-scanning direction can be adjusted.

In this case, even if the manufacturing accuracy of each opening varies, highly accurate width adjustment can be performed very easily. As a result, a high-quality image without unevenness can be obtained. Further, since it is not necessary to use an expensive member such as a lens for width adjustment, an inexpensive adjustment mechanism can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram when a laser beam having a Gaussian light amount distribution is used.

FIG. 2 is an explanatory diagram in the case of using a laser beam having a substantially rectangular light quantity distribution.

FIG. 3 is a plan view showing the configuration of the laser recording apparatus according to the embodiment;

FIG. 4 is an explanatory side view of the laser recording apparatus according to the embodiment.

FIG. 5 is a configuration diagram of an opening in the laser recording apparatus of the present embodiment.

FIG. 6 is an explanatory diagram of width adjustment by an opening member in the laser recording apparatus of the present embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Laser recording device 12 ... Exposure head 14 ... Drum 16A-16N ...
Light source unit 18 ... Semiconductor laser 20 ... Collimator lens 22, 26 ... Cylindrical lens 24 ... Opening 28 ... Imaging lens 38 ... Slit 40 ... Opening member F ... Recording film L ... Laser beam

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H04N 1/06 H04N 1/04 104Z F-term (Reference) 2C362 AA10 AA29 AA34 AA40 AA43 AA47 2H045 AG09 BA22 BA32 CB24 CB33 DA02 5C072 AA03 BA02 BA04 DA02 DA18 DA21 HA02 HA06 HA08 HB10 JA02 XA03 5F073 AA12 AB27 BA09 EA18 FA06

Claims (2)

[Claims] 1. An exposure recording apparatus for exposing and recording an image by main-scanning and sub-scanning a recording medium with a light beam, wherein light arranged in a sub-scanning direction and having a substantially rectangular light quantity distribution in the sub-scanning direction. A plurality of light sources for outputting beams; a first imaging optical system for imaging a near-field pattern of the light beam output from each of the light sources; and an imaging of the near-field pattern by the first imaging optical system An opening for adjusting the width of the near-field pattern in the sub-scanning direction by rotating about the main scanning direction, and an opening image of the near-field pattern adjusted by the opening. And a second imaging optical system that forms an image on a recording medium. 2. The apparatus according to claim 1, wherein a width of the opening in the sub-scanning direction is D0, a maximum rotation angle of the opening with respect to a plane orthogonal to an optical axis of the light beam is θmax, and 2 The imaging magnification of the imaging optical system is m,
Setting the rate of increase in the width of the near-field pattern in the sub-scanning direction at a position displaced by the distance ΔZ in the direction of the optical axis to n%, and setting D0 · sin θmax · m ² <ΔZ / n. Exposure recording device characterized by the following.