JP2003262817A - Exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an exposure device capable of improving the quality of an image formed on a recording medium. <P>SOLUTION: When laser beams L emitted from several semiconductor lasers LD are divided into several in a subscanning direction by an array refracting element 36 and condensed on recording film F, the laser beams L divided by the element 36 are temporarily condensed between a fiber array part 30 and the film F by a 1st optical system constituted of a 1st collimator lens 32A and a 1st condensing lens 38A, and at least a part of 1st-order diffracted light generated with the division of the laser beams L by the element 36 is intercepted by an array aperture plate 39 at the condensing position. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus,
In particular, it relates to an exposure device that forms an image on a recording medium by scanning exposure.

[0002]

2. Description of the Related Art Conventionally, a drum having a photosensitive material (recording medium) mounted on its outer peripheral surface is rotated in the main scanning direction, and a laser beam modulated according to image data of an image to be recorded on the photosensitive material. An exposure recording apparatus is used in which a two-dimensional image is recorded on the photosensitive material by scanning in the sub-scanning direction orthogonal to the main scanning direction.

In this type of exposure recording apparatus, in order to record an image with a low resolution, the spot diameter of the laser beam on the surface of the photosensitive material is increased and the recording pitch in the sub-scanning direction is increased, or A method has been adopted in which the size of the spot diameter and the recording pitch are not changed and pixels of the same image data are repeatedly recorded by the amount corresponding to the lowered resolution. On the other hand, when recording an image with a high resolution, the opposite method has been adopted.

However, in order to enlarge or reduce the spot diameter of the laser beam in this way, it is necessary to drive the lens of the optical system by using the drive mechanism, so that the apparatus becomes large and Cost will rise,
There was a problem. Further, when the resolution is lowered by repeatedly recording the pixels of the same image data by the amount corresponding to the lowered resolution, the recording pitch in the sub-scanning direction is constant, so that the recording speed cannot be improved. was there.

Therefore, in order to solve these problems, Japanese Patent Laid-Open No. 2000-284206 by the applicant of the present invention.
In the technique described in the publication, the light emitted from the light source is divided into a plurality of light beams, and the light condensing point on the recording medium by the light condensing optical system is
A plurality of condensing point generation means for generating a plurality in the sub-scanning direction of the recording medium and a sub-scanning control means for controlling the recording interval in the sub-scanning direction according to the resolution are provided, and the light is emitted from the light source. When recording an image by condensing light on a recording medium via a condensing optical system, depending on the resolution of the recorded image,
Adjusting the size of the beam spot by controlling the number of condensing points generated by the plurality of condensing point generating means in the sub-scanning direction and adjusting the recording interval of the beam spot in the sub-scanning direction. This makes it possible to efficiently record an image according to the resolution.

In this technique, a polarization optical element formed of a uniaxial crystal or a deflection angle prism is used as the plural condensing point generating means.

However, the above-mentioned Japanese Patent Laid-Open No. 2000-284.
In the technique described in Japanese Patent No. 206, when a polarizing optical element composed of a uniaxial crystal is used as a plurality of condensing point generating means, the uniaxial crystal is expensive, resulting in high cost. was there.

Further, in the case where the deflection angle prism is applied as the plural condensing point generating means in the technique described in the publication,
There has been a problem that the quality of recorded images may deteriorate.

That is, when a deflection prism is used as a plurality of converging point generating means in the technique described in the above publication, light is emitted from a focal position of a laser beam divided by the deflection prism and condensed by a condenser lens. The defocusing direction of the laser beam at the position shifted in the axial direction (depth direction) is asymmetric with respect to the optical axis direction.

This is because the light divided by the deflection prism is condensed by the condenser lens at different positions in the dividing direction of the focal position, so that when the incident side of the light is seen from the focal position, the divided light is divided. Are separated from each other, and when the light emission side is viewed from the focus position, the divided light beams come close to each other and then cross apart from each other. This phenomenon causes the recording medium to move in the depth direction. The allowable range of the arrangement position is reduced, and even if the displacement of the arrangement position in the depth direction is slight, the image quality of the recorded image on the recording medium may deteriorate.

Therefore, in order to solve these problems, Japanese Patent Application No. 2001-310537 filed by the applicant of the present invention.
The technique described in No. 1 is an exposure device that forms an image on a recording medium by scanning exposure, and a light source that emits a light beam emitted in a broad area at least in the sub-scanning direction, and a light emitted from the light source. A condensing optical system for condensing a beam on the recording medium, and an exposure apparatus having the refraction member having a unit surface shape for dividing one light beam into two are arranged in pairs in an array. The array refracting element is arranged so that the dividing direction of the light beam is substantially parallel to the broad area direction of the light beam emitted from the light source.

As a result, the light beam divided into two by the array pair of the array refracting element is composed of light corresponding to the number of array pairs. Therefore, since one focused spot is formed by the focused beams of the number of array pairs, when the divided light beams are superposed by shifting the focused spots by two at the focal positions, the focal positions are overlapped. From the incident side of the light beam to the emission side of the light beam from the focus position, the defocusing of each light beam is symmetric with respect to the optical axis direction. Can be improved.

The array refracting element can be made of any material as long as it can divide the light beam into two. Therefore, when the light beam is split according to the polarization direction. It is not always necessary to use the necessary uniaxial crystal, and the cost can be reduced.

By the way, for the purpose of improving the recording speed,
Each laser beam emitted from a plurality of light sources is guided by an optical fiber to a single exposure head, and the end portions of the laser beam emission ports of each optical fiber in the exposure head are arranged side by side in the sub-scanning direction. There is an exposure recording apparatus that simultaneously performs exposure with a plurality of laser beams emitted from a plurality of light sources.

When the technique described in the above-mentioned Japanese Patent Laid-Open No. 2000-284206 is applied to this type of exposure recording apparatus, one laser beam can be divided into a plurality of exposures, and therefore the recording speed can be increased. Can be further improved.

However, in the exposure recording apparatus using such an optical fiber, the polarization direction of the laser beam emitted from the optical fiber is sometimes changed by the external force displacement (vibration displacement, pressure displacement, twist displacement, temperature displacement, etc.) applied to the optical fiber. It may change from moment to moment. In this case, the light amounts of the laser beams divided into a plurality compete with each other, and the focused spot has an unstable shape, which deteriorates the image quality of the recorded image. There was a problem.

In order to solve this problem, therefore, in the technique described in Japanese Patent Application No. 2001-201407 filed by the applicant of the present invention, a light source for emitting light and a light emitted from the light source are recorded on a recording medium. In an exposure apparatus including a condensing optical system that condenses light into two and a polarization separation element that separates the light into two lights whose polarization directions are orthogonal to each other, the exposure apparatus includes A polarization direction control element, which is configured by arranging a ½ wavelength plate so that the crystal optical axis is inclined at an angle of a predetermined range including 45 degrees with respect to the polarization direction of the light beam separated by the polarization separation element, is arranged. Was there.

Although the crystal optical axis is also called the "optical axis", it will be referred to as "crystal optical axis" in the present specification. Further, the above-mentioned "angle in a predetermined range including 45 degrees" is ideally 45 degrees, but an angle within a range allowable in manufacturing the polarization direction control element, the polarization direction control element is applied. It means an angle within various allowable ranges such as an angle within the allowable range of the apparatus.

Here, the principle of the present technology will be briefly described with reference to FIG. Note that, here, a case will be described where the polarization direction control element of the present technology is configured by combining a half-wave plate and a transparent parallel plate that does not significantly affect the polarization direction of transmitted light. As shown in the figure, the polarization direction of the light separated by the polarization separation element is (x,
y), the polarization direction control element is arranged so that the direction of the crystal optical axis of the half-wave plate in the polarization direction control element is inclined by 45 degrees with respect to (x, y). To do. The coordinate system of the crystal optical axis in the half-wave plate at this time is (X, Y). In addition, here, on the assumption that there is no difference in light transmittance between the transparent parallel plate and the half-wave plate in the polarization direction control element, or the difference is negligibly small, the light amount of light incident on the half-wave plate is The polarization direction control element is arranged at a position where the amount of light is distributed so that the ratio to the amount of light that does not enter becomes 1: 1.

When the electric field vector α of the light incident on the polarization direction control element is α = (a, b) and the light incident on the ½ wavelength plate is considered, the (x, y) coordinate system is 45 degrees. Let A be the matrix for rotation, B be the matrix that delays the 1/2 wavelength phase of the light at the Y coordinate, and C be the matrix that rotates -45 degrees to return to the original (x, y) coordinate system. It is expressed as.

[0021]

[Equation 1]

Therefore, the electric field vector β of the light after passing through the half-wave plate is expressed as follows.

[0023]

[Equation 2]

Since α and β are set so as to be distributed at a ratio of 1: 1 as the light quantity distribution, the respective light quantity I
α and Iβ are expressed as follows.

[0025]

[Equation 3]

Therefore, the light quantity I when the respective lights are added is as follows.

[0027]

[Equation 4]

This result shows that when the light that has passed through the half-wave plate and the light that did not pass are added together, the light separated in each of the x and y polarization directions by the polarization splitting element is equal in light amount. It shows that it is separated by.

It should be noted that the transparent parallel plate provided in the polarization direction control element is not always necessary here, and other members (for example, those that do not greatly affect the polarization direction of the incident light) are used.
An ND (Neutral Density) filter may be applied instead of the transparent parallel plate, and it is also possible to provide a blank through state without providing these members.

Based on the above principle, Japanese Patent Application No. 2001-20
The polarization direction control element in the technique described in 1407,
A polarization direction control element provided on the upstream side in the optical axis direction of the light of a polarization splitting element for splitting light into two lights having polarization directions orthogonal to each other, and provided on the upstream side in the optical axis direction of the polarization splitting element. At this time, a part of the light is transmitted and at the same time, the crystal optical axis is inclined at an angle within a predetermined range including 45 degrees with respect to the polarization direction of the light separated by the polarization separation element. Since a wavelength plate is arranged and configured, when used in combination with a polarization separation element, it becomes possible to separate light with the same amount of light by the polarization separation element, and recording in an exposure recording apparatus using the polarization separation element. The image quality of the image can be improved.

[0031]

However, in the technique of Japanese Patent Application No. 2001-310537 described above, diffracted light is generated at the divided portion of the light beam in the array refraction element, and this influence causes the light beam to be collected on the recording medium. There is a problem in that the shape of the light spot becomes poor and, as a result, the quality of the image formed on the recording medium deteriorates.

Also in the technique of Japanese Patent Application No. 2001-201407 mentioned above, diffracted light is generated at the edge portion of the half-wave plate that constitutes the polarization direction control element, and this influence causes the collection of the light beam on the recording medium. There is a problem in that the shape of the light spot becomes poor and, as a result, the quality of the image formed on the recording medium deteriorates.

Here, the mechanism of generation of the diffracted light will be described. In addition, here, diffracted light when a plurality of refraction member pairs for dividing a light beam are arranged periodically will be described.

In this case, since the light beam is refracted in two directions by the plurality of pairs of refracting members, considering only the light beam emitted in one direction, the light beam passing through the refracting member is shown in FIG. It shows the same characteristics as when passing through the periodic aperture grating as shown.

Therefore, it suffices to solve the diffraction equation when light passes through this periodic aperture grating. The intensity distribution I (p) of the diffracted light when uniform light enters the periodic aperture grating is represented by the following equation (1). The diffraction angle pn (rad) of the n-th order diffracted light is expressed by the following equation (2).

[0036]

[Equation 5]

[0037]

[Equation 6]

Here, N is the number of periodic aperture gratings (refractive members), k is the wave number of light, d is the width (mm) of the periodic aperture gratings (refractive members), s is the aperture width (mm), and p is the diffraction angle. (Ra
d) and n are orders of diffracted light, and λ is a wavelength (mm) of incident light.

Here, as an example, FIG. 25 shows a graph when the following conditions are solved. In the figure, the horizontal axis represents the diffraction angle p, and the vertical axis represents the light intensity I (p).

(Condition) Width d = 3 (mm) of the periodic aperture grating, aperture width s = 1.5
(Mm), wavelength of light λ = 0.83 (μm) Further, the diffraction angle p1 of the first-order diffracted light at this time is as follows.

P1 = 2.8 × 10 ⁻⁴ (rad) As shown in FIG. 25, the light intensity I of the first-order diffracted light in this case is about 40% of the 0-th order light, The influence on the focused spot is remarkably large as compared with the diffracted light of other orders, and the quality of the image formed on the recording medium is remarkably deteriorated by the influence of the first-order diffracted light.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an exposure apparatus capable of improving the quality of an image formed on a recording medium.

[0043]

In order to achieve the above object, an exposure apparatus according to claim 1 is an exposure apparatus which forms an image on a recording medium by scanning exposure, and is broad in at least a sub-scanning direction. A light source that emits a light beam emitted in an area, a first optical system that focuses the light beam emitted from the light source between the light source and the recording medium, and a first optical system that focuses the light beam. And a second optical system for condensing the light beam on the recording medium, and a condensing position of the light beam by the light source and the first optical system, and the light beam is arranged in the sub-scanning direction. With respect to the light beam splitting means for generating diffracted light in accordance with the splitting, and the light beam splitting means arranged at the light beam converging position of the first optical system. Emitted with the division of And a, a light shielding means for shielding at least part of the first-order diffracted light.

According to the exposure apparatus of the first aspect, the light beam emitted from the light source for emitting the light beam emitted in the broad area is at least in the sub-scanning direction.
The optical system collects the light between the light source and the recording medium, and the collected light beam is collected on the recording medium by the second optical system. The light source includes various semiconductor lasers.

In converging the light beam on the recording medium as described above, in the present invention, the light splitting means arranged between the light source and the converging position of the light beam by the first optical system is used. The beam is divided into a plurality of beams in the sub-scanning direction, and at least the first-order diffracted light generated due to the division of the light beam by the light dividing unit is provided by the light-shielding unit arranged at the light beam converging position of the first optical system. A part is shaded.

That is, in the present invention, at least in the sub-scanning direction, the light beam emitted from the light source that emits the light beam emitted in the broad area is divided into a plurality of pieces in the sub-scanning direction by the light splitting means, and the light beam is emitted onto the recording medium. When converging on the first
The optical system once condenses between the light source and the recording medium, and at this condensing position, at least a part of the first-order diffracted light generated due to the division of the light beam by the light dividing means is shielded by the light shielding means, As a result, it is possible to reduce the influence of the first-order diffracted light generated by the light splitting means on the focused spot, and as a result, it is possible to improve the quality of the image formed on the recording medium.

As described above, according to the exposure apparatus of the first aspect, the light beam emitted from the light source that emits the light beam emitted in the broad area is used as the light source by the first optical system at least in the sub-scanning direction. Light splitting is performed between the light source and the light beam focusing position of the first optical system while focusing the light beam with the recording medium once, and focusing the focused light beam on the recording medium. Means for splitting the light beam into a plurality of parts in the sub-scanning direction, and the first-order diffraction caused by the splitting of the light beam by the light splitting means by the light shielding means arranged at the light beam focusing position by the first optical system. Since at least a part of the light is shielded, it is possible to reduce the influence of the first-order diffracted light generated by the light dividing means on the condensed spot, and as a result, the quality of the image formed on the recording medium is improved. Rukoto can.

The light shielding means according to the present invention is defined in claim 2.
As in the invention described above, at least a part of the first-order diffracted light may be shielded, and a rectangular opening may be provided to allow passage of a condensed spot of the light beam after being split by the light splitting means. .

As a result, since the rectangular opening can be easily formed, the light shielding means of the present invention can be manufactured at low cost.
And it can be easily manufactured.

Further, in the light splitting means according to the present invention, as in the invention described in claim 3, refraction members having a unit surface shape for splitting one light beam into two are arranged in pairs in an array form. And an array refraction element arranged such that the division direction of the light beam is substantially parallel to the broad area direction of the light beam emitted from the light source, or the light beam is polarized in the direction of polarization. Are orthogonal to each other 2
A polarization separation element that separates the light into two lights, and a crystal optical axis that is disposed between the light source and the polarization separation element and has a crystal optical axis of 45 degrees with respect to the polarization direction of the light beam that is separated by the polarization separation element. A polarization direction control element configured by arranging a ½ wavelength plate so as to be inclined at an angle in the range can be configured. The polarization separation element includes various prisms such as a Rochon Prism and a Wollaston Prism.

That is, according to the third aspect of the present invention, at least a part of the first-order diffracted light generated by the splitting of the light beam by the light splitting means, which is the main object of the present invention, is once collected. The technique of shading is described in Japanese Patent Application No. 2001-310537 and Japanese Patent Application No. 2001-2014.
It is applied to each invention of No. 07, and the same effect as the invention described in claim 1 or claim 2 can be exerted on these inventions.

On the other hand, an exposure apparatus according to a fourth aspect is the exposure apparatus according to any one of the first to third aspects, wherein resolution information indicating a resolution of an image formed on the recording medium by scanning exposure is provided. Input means for inputting, and when the resolution indicated by the resolution information is a predetermined first resolution, the light splitting means is retracted from the optical axis of the light beam, and the resolution indicated by the resolution information is Moving means for moving the light splitting means so that the light splitting means is positioned on the optical axis when the second resolution is lower than the first resolution.

According to the exposure apparatus of the fourth aspect, the resolution information indicating the resolution of the image formed on the recording medium by the scanning exposure is input by the input means, and the resolution indicated by the resolution information is predetermined. In the case of the first resolution, the light splitting means of the present invention is retracted from the optical axis of the light beam emitted from the light source, and the light when the resolution indicated by the resolution information is the second resolution lower than the first resolution. The light splitting means is moved by the moving means so that the splitting means is positioned on the optical axis.

As described above, according to the exposure apparatus of the fourth aspect, the resolution information indicating the resolution of the image formed on the recording medium by the scanning exposure is input, and the resolution indicated by the resolution information is predetermined. When the resolution is the first resolution, the light splitting means is retracted from the optical axis of the light beam emitted from the light source, and the light splitting is performed when the resolution indicated by the resolution information is the second resolution lower than the first resolution. Since the light dividing means is moved so that the means is located on the optical axis, the resolution when recording an image on the recording medium can be easily changed by only inputting the resolution information.

Further, as in the invention described in claim 5, a plurality of the light sources in the invention described in any one of claims 1 to 4 are provided along the dividing direction of the light beam by the light dividing means. By arranging and arranging the light beams emitted from each light source to be divided by the light dividing means and guided to the recording medium, not only the image quality of the recorded image can be improved but also the image can be recorded at high speed. .

[0056]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. In the following,
A case where the exposure apparatus of the present invention is applied to a laser recording apparatus will be described.

[First Embodiment] First, referring to FIG.
The configuration of the laser recording device 10A according to the first embodiment will be described. As shown in the figure, the laser recording device 10A according to the first embodiment includes an odd number of semiconductor lasers LD of 3 or more (15 in the present embodiment) each of which emits a laser beam, and each semiconductor laser. An exposure head 12 for converging each laser beam emitted from the LD, a drum 14 on which a recording film F on which an image is recorded is mounted and which is rotationally driven so that the recording film F moves in the main scanning direction, The sub-scanning motor 16 moves the exposure head 12 arranged on the ball screw 18 in the sub-scanning direction orthogonal to the main scanning direction by rotating the ball screw 18. In addition,
In this embodiment, the semiconductor laser LD shown in FIG.
An optical fiber coupled semiconductor laser having the intensity distribution shown in (A) is applied.

On the other hand, the exposure head 12 is provided with a lateral multimode fiber array section 30 which collects and emits each laser beam guided from the plurality of semiconductor lasers LD. The emitted laser beams are guided to the fiber array unit 30 by the transverse multimode optical fibers 20. In this embodiment, in order to make the laser beam have a high output,
A multimode optical fiber having a relatively large core diameter is used as the optical fiber 20.

FIG. 2 shows the fiber array section 30 of FIG.
The configuration when viewed in the direction of arrow B is shown. As shown in the figure, the fiber array unit 30 according to the present embodiment
Is provided with a pair of bases 30A in which a plurality of V-shaped grooves are provided so as to be adjacent to each other in the sub-scanning direction on opposite surfaces, and one optical fiber 20 is fitted into each V-shaped groove. It is configured. Therefore, the plurality of laser beams L emitted from each semiconductor laser LD are emitted from the fiber array unit 30 in two rows in the main scanning direction and at predetermined intervals along the sub scanning direction.

As the light source, each semiconductor laser LD may be one which emits light in a broadband area in one direction. At this time, the laser beam L emitted from each semiconductor laser LD is arranged so that the broadband area direction thereof coincides with the sub-scanning direction.

Further, as shown in FIG. 1, the exposure head 12
The first collimator lens 32A that makes the laser beam L emitted from the fiber array unit 30 into a substantially parallel light flux from the fiber array unit 30 side, and the array refraction element 3
6. First condensing lens 38 that temporarily condenses the laser beam L
A, the array aperture plate 39, the second collimator lens 32B for converting the laser beam L condensed by the first condenser lens 38A into a substantially parallel light beam, and the laser beam L converted into a substantially parallel light beam by the second collimator lens 32B are recorded. The second condenser lenses 38B for condensing light on the film F are arranged in order.

Further, the exposure head 12 has a rotation axis shown in FIG.
By rotating in the direction of arrow A, the array refraction element 36
An element moving motor 40 capable of inserting / removing the laser beam into / from the optical path of the laser beam L is provided.

The array refraction element 36 according to the present embodiment.
Are the laser beams L that are respectively incident on each other, as shown in FIG.
A pair of concave lens-shaped deflection angle prisms 36A and deflection angle prisms 36B having a unit surface shape that divide the laser beam L into two are linearly formed so that the division directions of the laser beams L coincide with each other and are along the division directions. It is arranged and configured,
The dividing direction of the laser beam L coincides with the sub-scanning direction, and it is positioned by the element moving motor 40 so that the laser beam L can be inserted and removed at a position where the far field pattern is formed by the first collimator lens 32A.

FIG. 4A shows a first focusing position where the laser beam L is once focused by the first focusing lens 38A when the array refracting element 36 is not positioned on the optical path of the laser beam L. The state of the focused spot formed in FIG. 4B is the state of the focused spot formed at the first focusing position when the array refracting element 36 is positioned on the optical path of the laser beam L in FIG. 4B. Are shown respectively.

As shown in FIG. 4 (A), when the array refracting element 36 is not positioned on the optical path of the laser beam L, the laser beam L emitted from each optical fiber 20.
Form a focused spot at the first focus position without being divided, but when the array refracting element 36 is positioned on the optical path of the laser beam L, as shown in FIG. Each laser beam L is divided into two along the sub-scanning direction, and each laser beam L is located at the first focus position.
Two focused spots will be formed for each. As a result, when the array refracting element 36 is not positioned on the optical path of the laser beam L on the recording film F, a condensed spot is formed in the same state as the arrangement state shown in FIG. When the element 36 is positioned on the optical path of the laser beam L, a focused spot is formed in the same state as the arrangement state shown in FIG.

That is, in the laser recording apparatus 10A according to this embodiment, the array refraction element 36 is moved to the laser beam L.
By selectively switching whether or not it is positioned on the optical path, the image to be recorded on the recording film F is switched to a predetermined resolution or a resolution higher than the predetermined resolution.

In this embodiment, as shown in FIG. 4A, when the array refracting element 36 is not located on the optical path of the laser beam L, that is, when image formation is performed on the high resolution side. The interval between the converging spots adjacent to each other in the sub-scanning direction is set to 4 · ε, and the other spots are formed so that the condensing spots of the other rows are formed at the central position in the sub-scanning direction between the converging spots adjacent to each other in the sub-scanning direction. Is configured. Thereby, an image having a scanning line pitch interval of 2 · ε can be recorded on the recording film F by one main scan.

Further, as shown in FIG. 4B, in the present embodiment, the shift amount of the focused spot on the recording film F corresponding to the two laser beams separated by the array refracting element 36 is ε. The relevant parts are set so that

On the other hand, FIG. 5 shows the array aperture plate 39 shown in FIG.
The configuration when viewed in the direction of arrow C is shown. As shown in the figure, the array aperture plate 39 according to the present embodiment includes
The same number of rectangular openings 39A as the semiconductor laser LD are formed.

The array aperture plate 39 is arranged at the above-mentioned first light collecting position (see also FIG. 1), and each aperture 39A
Is a state in which the array aperture plate 39 is arranged at the first focusing position, and the focusing spot SP shown in FIG.
In addition, the array refracting element 36 has a size and an arrangement position that can shield at least a part of the primary diffracted light RL in the sub-scanning direction generated by the division of the laser beam L.
In the array aperture plate 39 according to the present embodiment, each aperture 39A is arranged so that the sub-scanning direction edge coincides with the sub-scanning direction edge of the focused spot pair formed by the dividing action of the laser beam by the array refraction element 36. Is provided.
As a result, the effect of blocking the first-order diffracted light when the array aperture plate 39 has a rectangular shape can be maximized.

Next, the configuration of the control system of the laser recording apparatus 10A according to this embodiment will be described with reference to FIG. As shown in the figure, the control system includes an LD drive circuit 54 that drives the semiconductor laser LD according to image data,
An element movement motor drive circuit 56 that drives the element movement motor 40, a sub-scanning motor drive circuit 58 that drives the sub-scanning motor 16, an LD drive circuit 54, an element movement motor drive circuit 56, and a sub-scanning motor drive circuit 58 are controlled. And a control circuit 52 that operates. Here, in the control circuit 52,
Image data indicating an image to be recorded on the recording film F and resolution data indicating a resolution of image recording are supplied.

The semiconductor laser LD is the first light source of the present invention.
The optical system configured by the collimator lens 32A and the first condensing lens 38A is the first optical system of the present invention, and the optical system configured by the second collimator lens 32B and the second condensing lens 38B is the second optical system of the present invention. In the optical system, the array refracting element 36 serves as the light splitting means of the present invention, and the array aperture plate 39.
Corresponds to the light shielding means of the present invention, the element moving motor 40 corresponds to the moving means of the present invention, and the recording film F corresponds to the recording medium of the present invention.

Next, the operation of the laser recording apparatus 10A constructed as described above will be described with reference to the flowchart shown in FIG.

First, the operator inputs the resolution data indicating the resolution S of the image to be recorded in the laser recording device 10A (step 100). The resolution data and the image data of the image to be recorded are supplied to the control circuit 52,
The control circuit 52 outputs a signal adjusted based on these data to the LD drive circuit 54 and the element movement motor drive circuit 56.
And to the sub-scanning motor drive circuit 58. In the present embodiment, K0 (dpi) and 2 are used as the resolution S.
The following description will be given on the assumption that an image can be recorded at two kinds of resolutions of K0 (dpi).

The resolution input by the operator is 2 · K.
If 0 (dpi) (if affirmative determination is made in step 102), the element moving motor drive circuit 56 drives the element moving motor 40 to prevent the array refracting element 36 from being located on the optical path of the laser beam L. The refraction element 36 is moved (step 104). Further, in this case, the sub-scanning motor drive circuit 58 sets the feeding interval W of the exposure head 12 by the sub-scanning motor 16 in the sub-scanning direction as follows (step 106).

[0076]

[Equation 7]

However, N is the number of semiconductor lasers LD ('15' in this embodiment).

That is, when the resolution is 2 · K0 (dpi), the array refracting element 36 is removed from the optical path of the laser beam L so that the laser beam L is not divided in the sub-scanning direction. The resolution is twice as high as when the laser beam L is split.

When the movement of the array refracting element 36 and the setting of the feed interval in the sub-scanning direction are completed as described above, L
Based on the image data, the D drive circuit 54 controls the drive of each semiconductor laser LD so that the light emission amount corresponds to the data set according to the recording density (step 10).
8).

The laser beam L emitted from each semiconductor laser LD is converted into a substantially parallel light flux by the first collimator lens 32A, and then the first collimator lens 38A makes the first beam.
It is focused at the focus position. Then, the condensed laser beam L is diverged at the first condensing position as a boundary, and the diverged laser beam L is generated by the second collimator lens 3
After being made into a substantially parallel light flux by 2B, the second condenser lens 3
It is focused on the recording film F of the drum 14 by 8B.

In this case, on the recording film F, a beam spot S1 having the intensity distribution shown in FIG.
To S15 (FIG. 9A) are formed. As shown in FIG. 9A, the beam spots S1 to S15 are transmitted by the exposure head 12 in the sub-scanning direction at a pitch of the feeding interval W, and the drum 14 is rotated in the main scanning direction, so that the resolution is increased. A two-dimensional image of 2 · K0 (dpi) is formed on the recording film F (step 110).

Next, the resolution is from 2 · K0 (dpi) to K.
A case where it is changed to 0 (dpi) (when a negative determination is made in step 102) will be described. In this case, the element moving motor drive circuit 56 drives the element moving motor 40,
The array refracting element 36 is moved so that the array refracting element 36 is located on the optical path of the laser beam L (step 1).
12). Further, in this case, the sub-scanning motor drive circuit 58 sets the feed interval W ′ in the sub-scanning direction of the exposure head 12 by the sub-scanning motor 16 as follows (step 1).
14).

[0083]

[Equation 8]

That is, when the resolution is K0 (dpi), by arranging the array refracting element 36 on the optical path of the laser beam L, a plurality of laser beams L incident on the array refracting element 36 in the sub-scanning direction ( In the present embodiment, the laser beam is divided into '2') laser beams.
It realizes a resolution of one-half.

When the movement of the array refracting element 36 and the setting of the feed interval in the sub-scanning direction are completed as described above, L
The D drive circuit 54 controls the drive of each semiconductor laser LD based on the image data so that the amount of light emission is in accordance with the data set according to the recording density (step 11).
6).

The laser beam L emitted from each semiconductor laser LD is made into a substantially parallel light flux by the first collimator lens 32A, and then supplied to the array refracting element 36, and four laser beams L are provided in the sub-scanning direction for each laser beam L. Is divided into (beam sharing). Then, the four-divided laser beam passes through the first condensing lens 38A to reach the first condensing position, and as shown in FIG.
It is focused in the state of being divided into two.

That is, as shown in FIG. 10A, the array refracting element 36 is provided at a position where the laser beam L on the optical axis of each laser beam L becomes a substantially parallel light beam and near the position where the far field pattern can be formed. Figure 10 when placed
As shown in FIG. 10B, each laser beam L is once divided into four by the array refracting element 36, and each laser beam L divided into four by the array refracting element 36 is shown in FIG. 10A. The light is condensed by the first condensing lens 38 </ b> A, so that two are superposed in the sub-scanning direction at the first condensing position, and as a result, a state of being divided into two is obtained.

On the other hand, at the first focus position, the array aperture plate 3
By 9, the first-order diffracted light generated outside the both ends in the sub-scanning direction of each focused spot pair due to the division of the laser beam L by the array refraction element 36 is blocked.

Then, the laser beam L in the state where the first-order diffracted light is shielded is diverged at the first condensing position as a boundary and is made into a substantially parallel light beam by the second collimator lens 32B, and then the second condensing lens. 38B collects the light on the recording film F of the drum 14.

At this time, one focused spot is formed by the focused beams corresponding to the number of array pairs of the array refracting element 36, so that when the incident side of the laser beam is viewed from the focal position (position of the recording film F). The blur direction of each laser beam becomes symmetrical with respect to the optical axis direction when the emission side of the laser beam is viewed from the focus position, and as a result, the quality of the recorded image in the laser recording device 10A can be improved. .

Further, in each of the focused spot pairs formed on the recording film F, the first-order diffracted light generated outside the both ends in the sub-scanning direction by the action of the array refracting element 36 is blocked by the array aperture plate 39. The influence of the first-order diffracted light on the focused spot can be reduced, and as a result, the quality of the recorded image can be improved.

In this case, the recording film F is shown in FIG.
The beam spots S1 ′ to S1 having the two intensity distributions shown in (B), that is, the intensity distributions in which the respective intensity distributions of the laser beam divided into two are combined in the sub-scanning direction.
5 '(FIG. 9 (B)) is formed.

The beam spots S1 'to S15' are
As shown in FIG. 9B, the exposure head 12 is fed in the sub-scanning direction at a pitch of a feed interval W ′, and the drum 14
Is rotated in the main scanning direction, the resolution becomes K0.
A two-dimensional image of (dpi) is formed on the recording film F (step 110).

As described above, the resolution of the recorded image is set to 2 · K0.
When (dpi) is changed to K0 (dpi), the beam spots S1 to S15 are changed to beam spots S1 ′ simply by inserting the array refracting element 36 in the optical path of the laser beam L.
To S15 ', the image can be recorded at high speed because the sub-scanning speed is increased.

Similarly, the resolution can be changed from K0 (dpi) to 2.K0 (dpi).

The processing of step 100 corresponds to the input means of the present invention.

As described in detail above, in the laser recording apparatus 10A according to the first embodiment, the semiconductor laser LD
The laser beam L emitted from the fiber array unit 3
0 and the recording film F are once condensed, and the condensed laser beam L is condensed on the recording film F.
The array refraction element 36 arranged between the fiber array section 30 and the first condensing position divides the laser beam L into two in the sub-scanning direction and the array aperture arranged at the first condensing position. Since the plate 39 shields at least a part of the first-order diffracted light generated by the division of the laser beam L by the array refraction element 36, it is possible to reduce the influence of the first-order diffracted light on the focused spot. As a result, the quality of the image formed on the recording film F can be improved.

In the laser recording apparatus 10A according to the first embodiment, the array aperture plate 39 shields at least a part of the first-order diffracted light and condenses the laser beam after splitting by the array refracting element 36. Since it has a rectangular opening through which the spot passes, the opening can be easily formed, and the array opening plate 39 can be manufactured at low cost.
And it can be easily manufactured.

In the present embodiment, the case where the concave refraction prism 36A and the deflection prism 36B each having a concave lens shape are arranged as the array refracting element 36 is applied, but the present invention is not limited to this. However, the present invention is not limited to this, and any one can be applied as long as the refracting members having a unit surface shape that divides one light beam into two are arranged in pairs in an array. can do.

FIG. 11 shows an example (plan view) of an array refracting element having a shape other than the array refracting element 36 shown in the present embodiment. The array refracting element shown in FIG. 11A is formed by forming a pair of unit surface shapes that are convex toward the laser beam emission side in a linear shape along the sub-scanning direction. The array refracting element shown in FIG. 11B has a surface formed parallel to the laser beam incident side in the optical axis direction of the laser beam and one end of the surface on the laser beam incident side. Formed by forming a pair of unit surface shapes, which are a combination of the surfaces formed so as to incline with respect to the optical axis direction of the laser beam from the section, in a straight line along the sub-scanning direction Is. Furthermore, the array refracting element shown in FIG.
A surface formed so as to be parallel to the optical axis direction of the laser beam with respect to the emission side of the laser beam, and an inclination from the one end of the surface on the laser beam incident side with respect to the optical axis direction of the laser beam. The unit surface shape, which is a combination of the formed surface and the respective surfaces, is formed in a linear shape along the sub-scanning direction. Note that FIG. 11B
In the array refraction element shown in FIG. 11, the unit surface shape is convex toward the laser beam incident side, and FIG.
In the array refracting element shown in (C), the unit surface shape is concave with respect to the laser beam emitting side.

It goes without saying that an array refracting element integrally formed so as to have the same shape as the array refracting element 36 according to the present embodiment can also be applied.

Even when these array refracting elements are applied, the same effects as in the present embodiment can be obtained.

[Second Embodiment] In the first embodiment,
The case where the array refracting element of the present invention is arranged at a site where light becomes a substantially parallel light flux and the incident light is divided into different angles and emitted is described. However, in the second embodiment, A description will be given of a mode in which the array refraction element is arranged at a portion where light is converged, and the incident light is divided and emitted so as to be substantially parallel to each other.

First, the configuration of the laser recording apparatus 10B according to the second embodiment will be described with reference to FIG. Incidentally, the laser recording device 10A shown in FIG.
The same components as in FIG. 1 are assigned the same reference numerals as those in FIG. 1 and their description is omitted.

As shown in the figure, in the laser recording apparatus 10B according to the second embodiment, an array refraction element 36 'is used in place of the array refraction element 36, and the array refraction element 36' is the first. The difference from the laser recording apparatus 10A according to the first embodiment described above is that it is provided between the condenser lens 38A and the array aperture plate 39 at the location where the laser beam L converges.

Array refraction element 3 according to the second embodiment
As shown in FIG. 14B, 6'denotes a unit surface shape that splits each incident laser beam L into two and emits the two split laser beams so as to be substantially parallel to each other. A pair of refraction members included in the laser beam L are formed linearly so that the division directions of the laser beams L coincide with each other and the division directions of the laser beam L are in the sub-scanning direction. Positioning is performed by the element moving motor 40 so as to coincide with each other.

When the resolution is set to K0 (dpi), the laser beam L emitted from each semiconductor laser LD is converted into a substantially parallel light beam by the first collimator lens 32A, and then, as shown in FIG. 14 (A). Is supplied to the first condenser lens 38A and condensed.

The laser beams L condensed by the first condenser lens 38A are respectively supplied to the array refracting element 36 ', and as shown in FIG. 14B, four laser beams L are arranged in the sub-scanning direction for each laser beam L. And the divided two laser beams are emitted from each of the pair of portions corresponding to the unit surface shape of the array refraction element 36 ′ so as to be parallel to each other. And this 4
The divided laser beams are superposed two by two in the sub-scanning direction at the first converging position, and as a result, each laser beam L is condensed in two divided states.

On the other hand, at the first focus position, the array aperture plate 3
9, the laser beam L by the array refraction element 36 '
The first-order diffracted light generated outside the both ends of each focus spot pair in the sub-scanning direction due to the division is blocked.

Then, the laser beam L in a state in which the first-order diffracted light is shielded is diverged at the first condensing position as a boundary and is made into a substantially parallel light beam by the second collimator lens 32B, and then the second condensing lens. 38B collects the light on the recording film F of the drum 14.

At this time, one focused spot is formed by the focused beams of the number of array pairs of the array refracting element 36 ', so that when the incident side of the laser beam is seen from the focal position,
When looking at the emission side of the laser beam from the focus position, the blur direction of each laser beam is symmetric with respect to the optical axis direction,
As a result, the image quality of the recorded image in the laser recording device 10B can be improved.

Further, in each of the focused spot pairs formed on the recording film F, the first-order diffracted light generated outside the both ends in the sub-scanning direction by the action of the array refracting element 36 'is blocked by the array aperture plate 39. The influence of the first-order diffracted light on the focused spot can be reduced, and as a result, the quality of the recorded image can be improved.

In this case, the recording film F is shown in FIG.
The beam spots S1 ′ to S1 having the two intensity distributions shown in (B), that is, the intensity distributions in which the respective intensity distributions of the laser beam divided into two are combined in the sub-scanning direction.
5 '(FIG. 9 (B)) is formed.

The beam spots S1 'to S15' are
As shown in FIG. 9B, the exposure head 12 is fed in the sub-scanning direction at a pitch of a feed interval W ′, and the drum 14
Is rotated in the main scanning direction, the resolution becomes K0.
A two-dimensional image of (dpi) is formed on the recording film F.

On the other hand, when forming an image having a resolution of 2 · K0 (dpi), the array refracting element 36 ′ is moved so as not to be located on the optical path of the laser beam L, and then, as shown in FIG.
The beam spots S1 to S15 shown in FIG.

As described in detail above, in the laser recording apparatus 10B according to the second embodiment, the semiconductor laser LD
The laser beam L emitted from the fiber array unit 3
0 and the recording film F are once condensed, and the condensed laser beam L is condensed on the recording film F.
The array refracting element 36 'arranged between the first condensing lens 38A and the first condensing position divides the laser beam L into two in the sub-scanning direction and is arranged at the first condensing position. Since the array aperture plate 39 shields at least a part of the first-order diffracted light generated by the division of the laser beam L by the array refracting element 36 ′, the influence of the first-order diffracted light on the focused spot can be reduced. As a result, the quality of the image formed on the recording film F can be improved.

Further, in the laser recording apparatus 10B according to the second embodiment, the array aperture plate 39 shields at least a part of the first-order diffracted light and collects the laser beam after the division by the array refraction element 36 '. Since it has a rectangular opening through which the light spot passes, the opening can be easily formed, and the array opening plate 39 can be easily manufactured at low cost.

On the other hand, in the laser recording devices 10A and 10B according to each of the above-described embodiments, the array refracting element is provided between the fiber array section 30 and the recording film F, and the laser beam dividing direction is a broad area of the laser beam. Since it is arranged so as to be parallel to the direction, the blur direction of the laser beam at a position deviated from the focus position of the laser beam in the front-back direction of the optical axis (depth direction) is symmetrical with respect to the optical axis direction. As a result, the image quality of the recorded image can be improved, and the array refracting element can be constructed at a lower cost as compared with the case where a uniaxial crystal is used. As a result, the apparatus can be manufactured at a low cost. Can be composed of

Further, in the laser recording devices 10A and 10B according to each of the above embodiments, since the array refracting element is arranged at the position where the far field pattern of the laser beam can be formed, the laser beam emitted from each semiconductor laser LD is The array refractive element can be similarly acted on all of L.

Further, in the laser recording apparatuses 10A and 10B according to each of the above embodiments, resolution information indicating the resolution of an image formed on the recording film F by scanning exposure (corresponding to "resolution data" in each of the above embodiments). ) Is input, and the resolution indicated by the resolution information is a predetermined first resolution (2.K0 (dp in the above embodiments)).
i)), the array refraction element is a semiconductor laser LD.
The second resolution, which is retracted from the optical axis of the laser beam emitted from the device, and whose resolution indicated by the resolution information is lower than the first resolution (K0 (dp
In the case of i)), since the array refraction element is moved so that it is located on the optical axis,
The resolution at the time of recording an image on the recording film F can be easily changed only by inputting the resolution information.

In the second embodiment described above, the case where the array refraction element 36 'is arranged at the portion where the laser beam is focused has been described. However, the present invention is not limited to this. The beam may be diverged, that is, disposed between the fiber array unit 30 and the first collimator lens 32A. Also in this case, the same effect as that of the second embodiment can be obtained.

[Third Embodiment] First, the configuration of a laser recording apparatus 10C according to the third embodiment will be described with reference to FIG. In the figure, the same components as those of the laser recording apparatus 10A shown in FIG. 1 are designated by the same reference numerals as those in FIG. 1 and their explanations are omitted.

As shown in the figure, the laser recording apparatus 10C according to the third embodiment is different from the first embodiment only in that a polarization direction control element 34 and a polarization separation element 37 are used in place of the array refraction element 36. Laser recording apparatus 1 according to one embodiment
It is different from 0A.

The polarization separation element 37 according to the present embodiment is
As shown in FIG. 16, the laser beam L, which is formed by bonding two uniaxial crystals 37A and 37B whose crystal optical axes are orthogonal to each other, is separated into an ordinary ray and an extraordinary ray with respect to the sub-scanning direction of the recording film F. A uniaxial crystal that is a Rochon prism and has, for example, a crystal optical axis of the uniaxial crystal 37A arranged on the incident side of the laser beam L set parallel to the optical axis of the laser beam L and arranged on the emitting side of the laser beam L. The crystal optical axis of the crystal 37B is set in a direction orthogonal to the optical axis of the laser beam L and the sub-scanning direction. In this case, the ordinary ray goes straight through the polarization separation element 37, and the extraordinary ray is refracted in the sub-scanning direction by the polarization separation element 37.

As the polarization separating element 37, the crystal optical axis of the uniaxial crystal 37A is set to be orthogonal to the optical axis of the laser beam L and parallel to the sub-scanning direction.
A Wollaston prism in which the crystal optical axis of B is set in a direction orthogonal to the optical axis of the laser beam L and the sub-scanning direction may be applied.

Further, the polarization separation element 37 does not necessarily have to separate the laser beam L into an ordinary ray and an extraordinary ray, and may be any one that separates the laser beam L into two lights having different polarization directions.

On the other hand, in the polarization direction control element 34 according to the present embodiment, as shown in FIGS. 17A and 17B, the glass plate 34B is used as a base and the polarization axis direction of the polarization separation element 37 is adjusted. When provided on the upstream side, a part of the laser beam L is transmitted and the crystal optical axis is inclined by about 45 degrees with respect to the polarization direction of the light separated by the polarization separation element 37. It is configured by disposing a wave plate 34A. Further, here, a plurality of ½ wavelength plates 34A are arranged at predetermined intervals D so that the area ratio of the light incident regions of the ½ wavelength plate 34A and the glass plate 34B is approximately 1: 1. Both ends (portions through which the laser beam L does not pass) of each are bonded to the glass plate 34B.

As described above, the polarization direction control element 34 according to the present embodiment has the laser beam L of the half-wave plate 34A.
Of the laser beam L not incident on the half-wave plate 34A, that is, the glass plate 34.
The area ratio to the region where the laser beam L of B is incident is about 1
A plurality of half-wave plates 34A are arranged at predetermined intervals D in the entire incident region of the laser beam L so as to be paired with one another. However, based on the device specifications of the laser recording device 10C and the like. Then, the area ratio of the regions of the half-wave plate 34A and the glass plate 34B on which the laser beam L is incident is
The two light beams of the two laser beams obtained by the polarization separation element 37 may be configured to have substantially the same light amount. Further, the laser beam L that has passed through the half-wave plate 34A and the laser beam L that has not passed therethrough (that is, the laser beam L that has transmitted only the glass plate 34B).
It is also possible to adjust the arrangement position of the half-wave plate 34A so that the light amounts of the two are substantially the same. Since the configurations of these polarization direction control elements are substantially the same as those shown in FIG. 17, other illustrations of these polarization direction control elements are omitted.

Here, the case where the polarization direction control element 34 configured as described above is not used, and the case where the polarization direction control element 34 is used
The separation state of the laser beam by the polarization separation element 37 in the case of using will be described. First, with reference to FIG. 18, the separation state of the laser beam when the polarization direction control element 34 is not used will be described.

As shown in FIG. 18A, for example, when a laser beam having a polarization of e1 + e2 (a laser beam having a polarization inclined by 45 degrees with respect to the polarization e1) is incident on the polarization separation element 37, the light beam is evenly divided into two. It is separated into two polarized lights e1 and e2.

On the other hand, as shown in FIG.
When the laser beam of No. 1 is incident on the polarization separation element 37, only the laser beam of polarized light e1 is emitted from the polarization separation element 37. Therefore, in this case, it is difficult to evenly separate the two laser beams.

Next, referring to FIG. 19, description will be made on the separation state of the laser beam when the polarization direction control element 34 is used.

As shown in FIG. 19A, the polarized light is e1 +
When the laser beam of e2 (the laser beam of the polarized light inclined by 45 degrees with respect to the polarized light e1) is incident on the glass plate 34B, it is transmitted without changing the polarization direction, and this laser beam is incident on the polarization separation element 37. Thus, the two polarized lights e1 and e2 are evenly separated. On the other hand, the polarized light is e
When the 1 + e2 laser beam is incident on the ½ wavelength plate 34A, the crystal optical axis is inclined by 45 degrees with respect to the polarized light e1, so that the laser beam is transmitted without changing the polarization direction, and this laser beam is polarized and separated. The light enters the element 37 and is equally divided into two polarized lights e1 and e2.

On the other hand, as shown in FIG.
When the laser beam of No. 1 is incident on the glass plate 34B,
The laser beam is transmitted without changing the polarization direction, enters the polarization separation element 37, and emits the laser beam of only the polarized light e1. On the other hand, when the laser beam of the polarized light e1 is incident on the half-wave plate 34A, the crystal optical axis is inclined by 45 degrees with respect to the polarized light e1 and is emitted as the polarized light e2 orthogonal to the polarized light e1. Then, this laser beam enters the polarization separation element 37 and emits a laser beam of only the polarized light e2. Therefore, although the positions are spatially different, it is possible to divide the laser beam evenly as a whole.

Since the configuration of the control system of the laser recording apparatus 10C according to this embodiment is the same as that of the laser recording apparatus 10A according to the first embodiment (see FIG. 7), the description thereof is omitted here. To do. The optical system configured by the polarization direction control element 34 and the polarization separation element 37 corresponds to the light splitting means of the present invention.

Next, the operation of the laser recording apparatus 10C configured as described above will be described with reference to the flowchart shown in FIG.

First, the operator inputs resolution data indicating the resolution of an image to be recorded in the laser recording device 10C (step 200). The resolution data and the image data of the image to be recorded are supplied to the control circuit 52, and the control circuit 52 outputs the signals adjusted based on these data to the LD drive circuit 54, the element movement motor drive circuit 56 and the sub-scanning. It is supplied to the motor drive circuit 58. In the present embodiment, the resolutions R (dpi) and 2 · R are
The following description will be made assuming that an image can be recorded at two types of resolutions (dpi).

The resolution input by the operator is 2 · R.
If it is (dpi) (if affirmative determination is made in step 202), the element moving motor drive circuit 56 drives the element moving motor 40, and the polarization separation element 37 is polarized and separated so that it is not located on the optical path of the laser beam L. The element 37 is moved (step 204). In this case, the sub-scanning motor drive circuit 58 controls the exposure head 12 by the sub-scanning motor 16.
The feed interval W in the sub-scanning direction is set as in the above equation (3) (step 206).

That is, when the resolution is 2.multidot.R (dpi), the polarization beam splitting element 37 is removed from the optical path of the laser beam L to move the laser beam L to 2 in the sub-scanning direction.
The two laser beams (the ordinary ray and the extraordinary ray) are not separated from each other, thereby achieving a resolution twice as high as that when separating the laser beam L.

When the movement of the polarization separation element 37 and the setting of the feed interval in the sub-scanning direction are completed as described above, the LD
The drive circuit 54 controls each semiconductor laser L according to the image data.
The drive of D is controlled (step 208).

The laser beam L emitted from each semiconductor laser LD is made into a substantially parallel light flux by the first collimator lens 32A, and then enters the polarization direction control element 34.
The laser beam L incident on the polarization direction control element 34 is emitted without changing the polarization direction of the laser beam incident on the glass plate 34B. Regarding the laser beam incident on the half-wave plate 34A, the polarization direction of the polarized light whose polarization direction coincides with the crystal optical axis of the half-wave plate 34A is not changed and the polarization direction is the crystal optical axis. The polarized light that does not coincide with is emitted with its polarization direction changed to a direction corresponding to the angle formed by the polarization direction and the crystal optical axis.

The laser beam L emitted from the polarization direction control element 34 is condensed at the first condensing position via the first condensing lens 38A. The condensed laser beam L is diverged at the first condensing position as a boundary. The diverged laser beam L is converted into a substantially parallel luminous flux by the second collimator lens 32B, and then the second condensed laser beam L is collected. The light is focused on the recording film F of the drum 14 by the optical lens 38B.

In this case, on the recording film F, a beam spot S1 having the intensity distribution shown in FIG.
To S15 (FIG. 9A) are formed. As shown in FIG. 9A, the beam spots S1 to S15 are transmitted by the exposure head 12 in the sub-scanning direction at a pitch of the feeding interval W, and the drum 14 is rotated in the main scanning direction, so that the resolution is increased. A two-dimensional image of 2 · R (dpi) is formed on the recording film F (step 210).

Next, the resolution is from 2 · R (dpi) to R.
The case where it is changed to (dpi) (when a negative determination is made in step 202) will be described. In this case, the element moving motor drive circuit 56 drives the element moving motor 40 to move the polarization separating element 37 so that the polarization separating element 37 is located on the optical path of the laser beam L (step 21).
2). Further, in this case, the sub-scanning motor drive circuit 58 sets the feed interval W'of the exposure head 12 by the sub-scanning motor 16 in the sub-scanning direction as in the above equation (4) (step 214).

That is, when the resolution is R (dpi), the laser beam L incident on the laser beam splitter L is divided into two in the sub-scanning direction by positioning the laser beam splitter L on the optical path of the laser beam L. The laser beam (ordinary ray and extraordinary ray) is separated, and this realizes a resolution that is half that of the case where the laser beam L is not separated.

When the movement of the polarization separation element 37 and the setting of the feed interval in the sub-scanning direction are completed as described above, the LD
The drive circuit 54 controls each semiconductor laser L according to the image data.
The drive of D is controlled (step 208).

The laser beam L emitted from each semiconductor laser LD is made into a substantially parallel light beam by the first collimator lens 32A, and then enters the polarization direction control element 34.
The laser beam L incident on the polarization direction control element 34 is emitted without changing the polarization direction of the laser beam incident on the glass plate 34B. Regarding the laser beam incident on the half-wave plate 34A, the polarization direction of the polarized light whose polarization direction coincides with the crystal optical axis of the half-wave plate 34A is not changed and the polarization direction is the crystal optical axis. The polarized light that does not coincide with is emitted with its polarization direction changed to a direction corresponding to the angle formed by the polarization direction and the crystal optical axis.

The laser beam L emitted from the polarization direction control element 34 is supplied to the polarization separation element 37, and both ordinary rays and extraordinary rays are transmitted. Then, the ordinary ray and the extraordinary ray pass through the first condensing lens 38A to the first condensing position, and 2 for each laser beam as shown in FIG. 4B.
It is focused in the state of being divided into two.

On the other hand, at the first focus position, the array aperture plate 3
9, the polarization direction control element 34 and the polarization separation element 37
The first-order diffracted light generated outside the both ends in the sub-scanning direction of each focused spot pair due to the division of the laser beam L by is blocked.

Then, the laser beam L in a state where the first-order diffracted light is shielded is diverged at the first condensing position as a boundary and is made into a substantially parallel light beam by the second collimator lens 32B, and then the second condensing lens. 38B collects the light on the recording film F of the drum 14.

At this time, in each of the focused spot pairs formed on the recording film F, the first-order diffracted light generated outside the both ends in the sub-scanning direction by the action of the polarization direction control element 34 is blocked by the array aperture plate 39. Therefore, the influence of the first-order diffracted light on the focused spot can be reduced, and as a result, the quality of the recorded image can be improved.

In this case, the recording film F is shown in FIG.
A beam spot S1 'consisting of two intensity distributions shown in (B), that is, an intensity distribution in which the intensity distribution by the ordinary ray and the intensity distribution by the extraordinary ray are combined in the sub-scanning direction.
S15 '(FIG. 9 (B)) is formed.

The beam spots S1 'to S15' are
As shown in FIG. 9B, the exposure head 12 is fed in the sub-scanning direction at a pitch of a feed interval W ′, and the drum 14
Is rotated in the main scanning direction, the resolution becomes R (d
A two-dimensional image of pi) is formed on the recording film F (step 210).

As described above, the resolution of the recorded image is set to 2 · R.
When (dpi) is changed to R (dpi), the beam spots S1 to S15 are changed to beam spots S1 'to S1 only by inserting the polarization separation element 37 in the optical path of the laser beam L.
The image can be easily enlarged to 15 'and the sub-scanning speed is increased, so that image recording can be performed at high speed.

Similarly, the resolution is changed from R (dpi) to 2
-It can be changed to R (dpi). The process of step 200 corresponds to the input means of the present invention.

As described in detail above, in the laser recording apparatus 10C according to the third embodiment, the semiconductor laser LD
The laser beam L emitted from the fiber array unit 3
0 and the recording film F are once condensed, and the condensed laser beam L is condensed on the recording film F.
The laser beam L is divided into two with respect to the sub-scanning direction by the polarization direction control element 34 and the polarization separation element 37 arranged between the fiber array section 30 and the first focus position, and the first focus position. Since at least a part of the first-order diffracted light generated due to the division of the laser beam L by the polarization direction control element 34 and the polarization separation element 37 is shielded by the array aperture plate 39 arranged at, the collection of the first-order diffracted light is performed. The influence on the light spot can be reduced, and as a result, the quality of the image formed on the recording film F can be improved.

Further, in the laser recording apparatus 10C according to the third embodiment, the array aperture plate 39 shields at least a part of the first-order diffracted light and condenses the laser beam after splitting by the polarization separation element 37. Since the rectangular openings through which the spots pass are formed, the openings can be easily formed, and the array opening plate 39 can be easily manufactured at low cost.

[Fourth Embodiment] In the third embodiment,
A mode in which the polarization separation element of the present invention is arranged at a site where light becomes a substantially parallel light flux and two lights are emitted at different angles has been described. However, in the fourth embodiment, polarization separation is performed. One mode in which the element is arranged at a site where the light diverges and two lights are emitted from different positions in the direction of light separation by the polarization separation element will be described.

First, the configuration of the laser recording apparatus 10D according to the fourth embodiment will be described with reference to FIG. The laser recording device 10 shown in FIG.
The same components as those in C are assigned the same reference numerals as those in FIG.
The description is omitted.

As shown in the figure, the laser recording apparatus 10D according to the fourth embodiment uses a polarization separation element 37 'made of a uniaxial crystal in place of the polarization separation element 37, and controls the polarization direction. The laser recording device 10C according to the third embodiment is different from the laser recording device 10C according to the third embodiment only in that the element 34 and the polarization separation element 37 'are arranged at a site between the fiber array section 30 and the first collimator lens 32A where the laser beam L diverges. It's different. In this case, the direction of the crystal optical axis of the polarization separation element 37 'is set so as to be between the optical axis direction of the laser beam L and the sub-scanning direction.

When the resolution is set to R (dpi), the laser beam L whose polarization direction is controlled by the polarization direction control element 34 becomes an ordinary ray and an extraordinary ray by the polarization separation element 37 'as shown in FIG. To be separated. In this case, the refractive index of the polarization separation element 37 'with respect to the ordinary ray is
Since it is constant regardless of the direction of the crystal optical axis, it is emitted from the virtual light emitting point Po on the optical axis of the laser beam L and guided to the first collimator lens 32A. On the other hand, the refractive index of the polarization beam splitting element 37 'for extraordinary rays differs depending on the incident direction of the laser beam L and the direction of the crystal optical axis, and the crystal optical axis is between the optical axis direction of the laser beam L and the sub-scanning direction. Since it is set, the laser beam L is emitted from the virtual light emitting point Pe displaced by a predetermined amount in the sub-scanning direction from the optical axis of the laser beam L and guided to the first collimator lens 32A.

As a result, the ordinary ray and the extraordinary ray pass through the first collimator lens 32A and the first condensing lens 38A and are displaced by a predetermined amount in the sub-scanning direction from the first converging position, as shown in FIG. As shown in FIG. 3, each laser beam is condensed in a state of being divided into two.

At the first focusing position, the array aperture plate 39 causes the polarization direction control element 34 and the polarization splitting element 37 'to split the laser beam L to the outside of both ends in the sub-scanning direction of each focusing spot pair. The generated first-order diffracted light is blocked.

Then, the laser beam L in a state where the first-order diffracted light is shielded is diverged at the first condensing position as a boundary and is made into a substantially parallel luminous flux by the second collimator lens 32B, and then the second condensing lens. By being focused on the recording film F of the drum 14 by 38B, beam spots S1 ′ to S15 ′ shown in FIG. 9B are obtained. As a result, an image having a resolution of R (dpi) can be formed.

At this time, in each of the focused spot pairs formed on the recording film F, the first-order diffracted light generated outside the both ends in the sub-scanning direction by the action of the polarization direction control element 34 is blocked by the array aperture plate 39. Therefore, the influence of the first-order diffracted light on the focused spot can be reduced, and as a result, the quality of the recorded image can be improved.

On the other hand, when an image having a resolution of 2 · R (dpi) is formed, the polarization beam splitting element 37 ′ is set to the laser beam L.
It is sufficient to control so that the beam spots S1 to S15 shown in FIG.

As described in detail above, in the laser recording apparatus 10D according to the fourth embodiment, the semiconductor laser LD
The laser beam L emitted from the fiber array unit 3
0 and the recording film F are once condensed, and the condensed laser beam L is condensed on the recording film F.
Fiber array unit 30 and first collimator lens 32A
The laser beam L is divided into two with respect to the sub-scanning direction by the polarization direction control element 34 and the polarization separation element 37 ′ disposed between the array aperture plate 39 arranged at the first condensing position. Since at least a part of the first-order diffracted light generated due to the division of the laser beam L by the polarization direction control element 34 and the polarization separation element 37 'is shielded, the influence on the focused spot of the first-order diffracted light is reduced. As a result, the quality of the image formed on the recording film F can be improved.

Further, in the laser recording apparatus 10D according to the fourth embodiment, the array aperture plate 39 shields at least a part of the first-order diffracted light and collects the laser beam after the splitting by the polarization separation element 37 '. Since it has a rectangular opening for passing the light spot, the opening can be easily formed, and the array opening plate 39 can be manufactured at low cost.
And it can be easily manufactured.

Further, the polarization direction control element 34 according to the third and fourth embodiments described above has the optical axis of the laser beam L of the polarization separation element 37 for separating the laser beam L into two laser beams whose polarization directions are orthogonal to each other. In the polarization direction control element provided on the upstream side in the direction, when part of the laser beam L is transmitted and is separated by the polarization separation element 37 when provided on the upstream side in the optical axis direction of the polarization separation element 37. The optical axis of the crystal is tilted about 45 degrees with respect to the polarization direction of
Since the / 2 wavelength plate 34A is arranged and configured, when used in combination with the polarization separation element 37, the polarization separation element 37 can separate the laser beam L with an equal light amount, and the polarization separation element 37 can be separated. It is possible to improve the image quality of a recorded image in the laser recording apparatus using the.

In the polarization direction control elements 34 according to the third and fourth embodiments, the region where the laser beam L of the half-wave plate 34A is incident and the laser beam which is not incident on the half-wave plate 34A are included. Area L, that is, the glass plate 34
Since the area ratio with respect to the region where the laser beam L of B is directly incident is about 1: 1, the intensity distribution of the separated laser beam can be made uniform.

The polarization direction control elements 34 according to the third and fourth embodiments are constructed by disposing a plurality of half-wave plates 34A at predetermined intervals in the entire incident region of the laser beam L. It can be created easily.

In the laser recording devices 10C and 10D according to the third and fourth embodiments, the polarization direction control element 34 as described above is used as the semiconductor laser LD and the polarization separation element 37.
Since the crystal optical axis of the half-wave plate 34A is inclined by about 45 degrees with respect to the polarization direction of the laser beam L separated by the polarization separation element 37, the polarization separation element 37 Thus, the laser beam L can be separated with an equal amount of light, and the image quality of the image when the image is recorded on the recording film F by the separated laser beam L can be improved.

Further, in the laser recording devices 10C and 10D according to the third and fourth embodiments, an element for moving the polarization separation element 37 so that the polarization separation element 37 is inserted and removed on the optical axis of the laser beam L. Since the moving motor 40 is provided, the polarization separating element 37 is moved by the element moving motor 40.
By inserting and removing the optical recording medium in the optical path, it is possible to easily change the resolution when recording an image on the recording film F.

Further, in the laser recording devices 10A to 10D according to the above-mentioned respective embodiments, a plurality of semiconductor lasers LD are arranged along the dividing direction of the laser beam L by the array refracting element or the polarization separating element, and emitted from each semiconductor laser LD. Since the laser beams L thus generated are divided by the array refracting element or the polarization separating element and guided to the recording film F, an image can be recorded at high speed.

The fourth embodiment has been described with respect to the case where the polarization direction control element 34 and the polarization separation element 37 'are arranged at the site where the laser beam diverges, but the present invention is not limited to this. Instead, for example, a configuration may be adopted in which the laser beam is converged, that is, between the first condensing lens 38A and the first condensing position. Also in this case, the same effect as that of the fourth embodiment can be obtained.

In the third and fourth embodiments, the case where the element moving motor 40 is configured so that only the polarization separation element 37 can be inserted into and removed from the optical path of the laser beam L has been described. Is not limited to this, and the element moving motor 40 may be used as the polarization direction control element 3.
4 and the polarization separation element 37 can be configured so that they can be inserted into and removed from the optical path of the laser beam L at the same time. Also in this case, the same effects as those of the third and fourth embodiments can be obtained.

Further, in each of the above-mentioned embodiments, the present invention is applied to laser recording devices 10A to 10D for performing multi-beam scanning.
However, the present invention is not limited to this, and the present invention can be applied to, for example, a laser recording device for performing a single beam scan in which a light source is composed of one semiconductor laser. Also in this case, the same effect as that of each of the above-described embodiments can be obtained.

[0178]

As described in detail above, according to the exposure apparatus of the present invention, the light beam emitted from the light source for emitting the light beam emitted in the broad area at least in the sub-scanning direction is emitted by the first optical device. The light beam is condensed between the light source and the recording medium by the system, the condensed light beam is condensed on the recording medium, and the light beam is arranged between the light source and the condensing position of the light beam by the first optical system. The light splitting means divides the light beam into a plurality of parts in the sub-scanning direction, and the light shielding means arranged at the light beam focusing position by the first optical system causes the light splitting means to divide the light beam. Since at least a part of the generated first-order diffracted light is shielded, it is possible to reduce the influence of the first-order diffracted light generated by the light splitting means on the focused spot, and as a result, the image formed on the recording medium. It is possible to improve the quality, the effect is obtained that.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram (plan view) of a laser recording device 10A according to a first embodiment.

FIG. 2 is a schematic configuration diagram (side view) of a fiber array unit 30 according to an embodiment.

FIG. 3 is a schematic configuration diagram (plan view) showing a configuration of an array refraction element 36 according to the first embodiment.

FIG. 4 is a diagram showing a state of a focused spot in the laser recording apparatus according to the embodiment, and FIG. 4A shows the first collection when the array refracting element or the polarization separating element is not located on the optical path of the laser beam L. The state of the focused spot formed at the light position is shown in (B) of the focused spot formed at the first focused position when the array refracting element or the polarization separating element is positioned on the optical path of the laser beam L. It is the schematic which shows each state.

FIG. 5 is a schematic configuration diagram showing a configuration of an array aperture plate 39 according to the embodiment.

FIG. 6 is a schematic configuration diagram showing a configuration of an opening 39A provided in the array opening plate 39 according to the embodiment.

FIG. 7 is a block diagram showing a configuration of a control system of the laser recording apparatus according to the embodiment.

FIG. 8 is a flowchart showing the flow of processing when image recording is performed according to resolution in the laser recording devices according to the first and second embodiments.

FIG. 9 is a schematic diagram showing a state of a beam spot on a recording film F by the laser recording apparatus according to the embodiment.

FIG. 10 is a schematic diagram (plan view) for explaining the operation of the laser recording apparatus 10A according to the first embodiment.

FIG. 11 is a schematic configuration diagram (plan view) showing another configuration example of the array refraction element of the present invention.

FIG. 12 is a graph showing an example of a state of intensity distribution of a laser beam at a focus point.

FIG. 13 is a schematic configuration diagram (plan view) of a laser recording device 10B according to a second embodiment.

FIG. 14A is a schematic diagram (plan view) for explaining the operation of the laser recording apparatus 10B according to the second embodiment,
(B) is a schematic diagram (plan view) for explaining the configuration and action of the array refraction element 36 ′ according to the second embodiment.

FIG. 15 is a schematic configuration diagram (plan view) of a laser recording device 10C according to a third embodiment.

FIG. 16 is a schematic diagram (plan view) for explaining the configuration and action of the polarization beam splitting element 37 according to the third embodiment.

17A is a schematic configuration diagram (a front view and a side view) of a polarization direction control element 34 according to the third and fourth embodiments, and FIG. 17B is a crystal optical axis of the polarization direction control element 34. It is the schematic which shows a direction.

FIG. 18 is a schematic diagram showing a laser beam separation state by a polarization separation element 37 when the polarization direction control element is not used in the laser recording apparatuses according to the third and fourth embodiments.

FIG. 19 is a schematic view showing a laser beam separation state by a polarization separation element 37 when a polarization direction control element 34 is used in the laser recording devices according to the third and fourth embodiments.

FIG. 20 is a flowchart showing the flow of processing when image recording is performed according to the resolution in the laser recording apparatuses according to the third and fourth embodiments.

FIG. 21 is a schematic configuration diagram (plan view) of a laser recording device 10D according to a fourth embodiment.

FIG. 22 is a schematic diagram (plan view) for explaining the operation of the polarization beam splitting element 37 ′ according to the fourth embodiment.

FIG. 23 is a schematic diagram for explaining the principle of the prior art.

FIG. 24 is a schematic diagram for explaining a mechanism of generation of diffracted light.

FIG. 25 is a graph for explaining the mechanism of generation of diffracted light.

[Explanation of symbols]

10A, 10B, 10C, 10D laser recording device 12 Exposure head 14 drums 16 Sub-scanning motor 20 optical fiber 30 Fiber array part 32A First collimator lens (first optical system) 32B Second collimator lens (second optical system) 34 Polarization direction control element (light splitting means) 34A 1/2 wave plate 34B glass plate 36 Array refraction element (light splitting means) 36A, 36B Declination prism 36 'Array refraction element (light splitting means) 37 Polarization separation element (light splitting means) 37 'Polarization separation element (light splitting means) 38A First condenser lens (first optical system) 38B Second condenser lens (second optical system) 39 Array aperture plate (light blocking means) 40 element moving motor (moving means) L laser beam LD semiconductor laser (light source) F Recording film (recording medium)

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03F 1/00 G03F 7/24 2H097 7/24 H01L 21/30 529 2H099 H01L 21/027 B41J 3/00 D 5F046 F Term (Reference) 2C362 AA10 AA26 AA34 AA40 AA43 AA47 BA25 BA58 BA85 BA86 CB71 2H042 AA09 AA15 AA25 2H045 AG09 2H052 BA02 BA07 BA09 BA12 2H095 AB15 AB23 AB25 2H097 A17 03

Claims (5)

[Claims] 1. An exposure apparatus for forming an image on a recording medium by scanning exposure, comprising: a light source for emitting a light beam emitted in a broad area at least in the sub-scanning direction; and the light beam emitted from the light source. A first optical system that collects light between the light source and the recording medium; a second optical system that collects the light beam collected by the first optical system onto the recording medium; And a condensing position of the light beam by the first optical system, the light beam is divided into a plurality in the sub-scanning direction, and diffracted light is generated in accordance with the division. Means, and a light-shielding means that is disposed at a light-focusing position of the light beam by the first optical system and that shields at least a part of the first-order diffracted light generated due to the light beam splitting by the light splitting means, Dew with Light equipment. 2. The light shielding means has a rectangular opening that shields at least a part of the first-order diffracted light and allows the light spot of the light beam after being split by the light splitting means to pass therethrough. The exposure apparatus according to claim 1. 3. The light splitting means is configured such that refracting members having a unit surface shape for splitting one light beam into two are arranged in pairs in an array, and the splitting direction of the light beam is An array refraction element arranged so as to be substantially parallel to the broad area direction of the light beam emitted from the light source, or a polarization separation element for separating the light beam into two lights whose polarization directions are orthogonal to each other And the crystal optical axis is 45 with respect to the polarization direction of the light beam that is arranged between the light source and the polarization separation element and is separated by the polarization separation element.
3. The exposure apparatus according to claim 1, further comprising: a polarization direction control element configured by arranging a ½ wavelength plate so as to be inclined at an angle of a predetermined range including a degree. 4. An input unit for inputting resolution information indicating a resolution of an image formed on the recording medium by scanning exposure, and when the resolution indicated by the resolution information is a predetermined first resolution. The light splitting means is retracted from the optical axis of the light beam, and the light splitting means is positioned on the optical axis when the resolution indicated by the resolution information is a second resolution lower than the first resolution. The exposure apparatus according to any one of claims 1 to 3, further comprising: a moving unit that moves the light splitting unit. 5. The exposure apparatus according to claim 1, wherein a plurality of the light sources are arranged along a dividing direction of the light beam by the light dividing means.