JP2001330965A - Image writing device, image output device, fine optical element manufacturing method for image writing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce a smooth half-tone image at a high speed without especially enhancing the resolution. SOLUTION: The luminous flux of beams emitted from a light source 2 per pixel unit is divided into plural spot beams by the fine aperture part groups 18 of a fine optical element 3, and the beams are emitted. The intensity of the beam emitted from the light source 2 is increased/decreased in accordance with the half-tone image to be reproduced. Thus, by increasing/decreasing the light intensity of the beam, the size of plural dots for forming one pixel on an image recording medium 1 is increased/decreased, thus, the smooth half-tone image is reproduced at a high speed without unnecessarily enhancing the resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a micro optical element for forming a spot shape of a beam emitted from a light source into a desired shape, a manufacturing method thereof, an image writing device, and an image output device.

[0002]

2. Description of the Related Art Conventionally, an image output apparatus for reproducing an image by scanning a beam emitted from a light source onto an image recording medium such as a photosensitive member, such as an electrophotographic printer, reproduces a halftone image. In such a case, the pixels forming the image are reproduced as an aggregate of finer spots, and the change in density is expressed by increasing or decreasing the number of spots. Such an example is disclosed in Japanese Unexamined Patent Publication No.
No. 56, JP-A-8-506704 and the like.

[0003]

According to the methods described in the above publications, in order to reproduce a smooth halftone, the resolution required for reproducing the finest line drawing included in an image is far greater. The image needs to be finely divided.

As an example, when the pixel density required to reproduce the line drawing information of an image is 600 dpi (the number of pixels per inch), to reproduce smooth gradation, one pixel is required.
Since pixels need to be divided into an 8 × 8 matrix, the resolution required for writing an image is 600 × 8 = 48.
00 dpi.

It is not impossible at present to write an image with a beam at this resolution. However, the image writing device capable of such a high resolution is the highest image writing device at present, and has the following problems in general use.

Since it is necessary to divide an image into extremely fine regions, the time required for image processing calculations is greatly increased. In order to reduce this time, it is necessary to incorporate an electronic computer having a more advanced processor, which increases the cost of the apparatus. At present, the processing capacity of a small computer that can be built in an image output device is limited, and it is difficult to perform 4800 dpi within the same time as 600 dpi even if a high-speed model is built in. .

[0007] Therefore, it is attempted to reproduce a smooth halftone image by dividing pixels into sufficiently small pieces at the stage of electronic information and writing a halftone matrix generated by software on an image recording medium by a high definition image writing device. According to the currently used method, it is possible to produce an image output device that reproduces a smooth halftone having no visual problem on a trial basis, but it is difficult to widely disseminate it as an industrial product.

Further, the number of write scan lines increases because the spot size becomes minute by subdividing pixels, but it is necessary to increase the number of rotations of the polygon scanner in order to increase the write speed. However, it has structural limitations.

An image writing apparatus in which a writing spot is miniaturized to about 4800 dpi can reproduce a smooth halftone although the image processing time is long as described above. However, even when a simple line drawing that does not need to reproduce a halftone is output, a long writing time is required, and there is a problem that it is not possible to respond to a user's request for a high-speed output.

An object of the present invention is to enable a smoother halftone image to be reproduced at a higher speed than before, without particularly increasing the resolution.

It is a further object of the present invention to achieve both a function of reproducing a smooth halftone and a function of outputting a simple line drawing image which does not need to reproduce a halftone at a high speed.

[0012]

According to a first aspect of the present invention, there is provided an image writing apparatus, comprising: a light converging element unit for converging a light beam of a beam emitted from a light source in a unit of one pixel; and a light beam converging by the light converging element unit. A first micro-opening disposed at a position to be scattered, a light-diffusing element disposed on an emission side of the first micro-opening, and a plurality of light beams of a beam diffused by the light-diffusing element. A micro-optical element having a plurality of second micro-apertures which are divided into spot lights and are provided in the same plane and a plurality of second micro-apertures, and a beam emitted from the light source according to a halftone to be reproduced And a scanning optical system that scans a beam emitted from the micro optical element onto an image recording medium.

Therefore, the beam emitted from the light source is focused by the light focusing element unit in a unit of one pixel, emitted from the first minute opening, diffused by the light diffusing element unit, and converted into a light beam by the minute opening group. It is divided and irradiated on the image recording medium. At this time, by increasing or decreasing the light intensity of the beam, the size of a plurality of dots forming one pixel on the image recording medium can be increased or decreased, so that a smooth halftone can be obtained without unnecessarily increasing the resolution. It can be reproduced. Further, since it is not necessary to increase the resolution more than necessary, it is possible to output an image at high speed.

According to a second aspect of the present invention, in the image writing apparatus according to the first aspect, the group of minute openings includes a second minute opening disposed at the center of the area of one pixel,
One or a plurality of second minute openings arranged around a second minute opening arranged at the center of the pixel area, and the diameter of the second minute opening is one pixel The diameter of the second minute opening located at a position from the center of the region toward the periphery is determined to be smaller.

Therefore, the size of the plurality of dots forming one pixel is large at the center and small at the periphery, so that the average density change in the image area becomes smooth. In addition, when the light intensity of the beam is reduced, the formation of dots from the small second small apertures in the periphery is suppressed and the number of dots is reduced, enabling a smoother halftone reproduction. Become.

According to a third aspect of the present invention, in the image writing apparatus according to the first or second aspect, the light focusing element section comprises:
A pyramid-shaped or conical-shaped inner surface whose optical path cross-sectional area gradually decreases from the light source side toward the first minute opening is formed by a micromirror.

Therefore, a high-precision light focusing element can be manufactured by a simple method by applying manufacturing equipment and a manufacturing process used for manufacturing a semiconductor or the like.

The invention described in claim 4 is the first to third aspects of the present invention.
In the image writing device according to any one of the above, the light diffusing element unit is a spherical, hemispherical, hyper-hemispherical shape, a minute integrating sphere such as a conical shape provided corresponding to the first minute opening. The minute opening group is arranged at a position on the integrating sphere facing the first minute opening.

Therefore, by applying manufacturing equipment and manufacturing processes used for manufacturing semiconductors and the like,
It is possible to manufacture a high-precision light-diffusing element portion having a small amount of light absorption and capable of effectively utilizing the energy of light from a light source by a simple method.

The invention according to claim 5 is the invention according to claims 1 to 4.
In the image writing device according to any one of the above, a microlens is formed on at least one of the opening surface of the first minute opening and the opening surface of the minute opening group.

Therefore, the light use efficiency is improved, and the image writing speed can be increased.

According to a sixth aspect of the present invention, there is provided an image output device, comprising: an image carrier having a photosensitive characteristic; and an image writing device according to any one of the first to fifth aspects, for writing an electrostatic latent image on the image carrier. A developing device for developing the electrostatic latent image written on the image carrier, and a transfer device for transferring an image developed on the image carrier to paper.

Therefore, it is possible to reproduce a smooth halftone without increasing the resolution more than necessary.
An image output device capable of outputting an image at high speed can be provided.

According to a seventh aspect of the present invention, there is provided the image output device, wherein an image carrier having a photosensitive characteristic and a plurality of electrostatic latent images of different colors are written on the image carrier. An image writing device, a developing device that develops an electrostatic latent image written on the image carrier for each different color, and a transfer device that transfers an image developed on the image carrier to paper The micro optical element of the image writing device, the irradiation position of the beam emitted from the second minute opening on the image carrier is such that the second minute opening of the second minute opening does not overlap between the colors. The position or the tilt angle of the optical path has been changed.

Therefore, it is possible to reproduce a smooth halftone without increasing the resolution more than necessary.
Provided is an image output device capable of outputting an image at a high speed, and further capable of preventing an overlap of dots of each color when outputting a color image and capable of outputting an image without color turbidity. be able to.

According to a eighth aspect of the present invention, there is provided a method for manufacturing a micro optical element in an image writing apparatus, wherein the light focusing element section according to the first or third aspect and the first micro aperture according to the first or third aspect are formed as a first micro aperture. A step of forming an etching mask having a pattern corresponding to the arrangement of the group of minute openings according to claim 1 or 2 on one surface of the second substrate; and etching the second substrate. And a step of digging a concave portion corresponding to the group of minute openings on one surface of the substrate, and an arrangement of the light diffusing element portion according to claim 1 or 2 on the other surface of the second substrate. A step of forming an etching mask of a pattern in alignment with the arrangement pattern of the group of minute openings, and etching the second substrate to form a concave portion corresponding to the light diffusion element portion on one surface of the substrate. Equivalent to the group of minute openings Forming the light diffusion element portion and the minute opening group into a predetermined shape by digging the hole to penetrate the concave portion, and forming a light diffusion surface for diffusing light on the inner surface of the light diffusion element portion. Bonding the first substrate on which the light focusing element portion and the first minute opening are formed, and the second substrate on which the minute opening group and the light diffusion element portion are formed And are sequentially performed.

Therefore, it is easy to match the centers of gravity of the first minute opening, the light diffusing element, and the minute opening group, and it is also possible to make the minute opening group located at the center of the light diffusing element part. Although the surrounding thickness is reduced, the second substrate before digging the light diffusion element portion is digged into a concave portion corresponding to a minute opening when the second substrate is thick, so that the second substrate is not damaged during the manufacturing process. It is possible to improve the yield by preventing it.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view illustrating a schematic configuration of the image writing device 1. As shown in FIG. 1, an image writing apparatus 1 subdivides a light beam of a beam emitted from a laser diode array 2 as a light source by a micro optical element 3 and converts the subdivided beam into an imaging lens 4.
An image is formed on the reflection surface 5a of the polygon scanner 5, and the polygon scanner 5 is rotationally driven by the polygon motor 6, thereby deflecting and scanning the beam emitted from the laser diode array 2, and transforming the scanned beam into f
The correction is performed by the θ lens system, that is, the cylinder lens 7 and the toroidal lens 8, and the light is returned by the reflecting mirror 9 and irradiated onto an image carrier (photosensitive drum) 10 as an image recording medium.

Here, a scanning optical system 11 includes a polygon scanner 5, which is rotationally driven by a polygon motor 6, a cylinder lens 7, a toroidal lens 8, and a reflecting mirror 9.
Are formed.

Further, the image writing apparatus 1 is provided with a laser diode array 2 according to a halftone to be reproduced.
Light intensity control means for increasing and decreasing the light intensity of the beam emitted from the light source. Although not shown, the light intensity control means is configured to input a signal corresponding to the output level from the light amount control circuit 12 to the laser diode array 2 when the output level is set by the setting unit.

FIG. 2 is an explanatory view showing the micro optical element 3 in cross section together with a light source. The light source may be a single light source such as a laser diode. In the present embodiment, the light source is a laser diode array 2 in which a plurality of laser diodes each irradiating a beam corresponding to one pixel are linearly arranged.

The micro optical element 3 has a first substrate 13 and a second substrate 14 joined to each other. And, on the first substrate 13, a plurality of light converging element portions 15 for converging light beams of beams emitted from a plurality of laser diodes included in the laser diode array 2 in units of one pixel,
A first minute opening 16 is formed at a position where the light beam is focused by these light focusing element portions 15. On the second substrate 14, a light diffusion element portion 17 and a group of minute openings 18 are formed.

FIGS. 3A and 3B show an enlarged view of a part of the structure of the micro optical element 3, wherein FIG. 3A is a front view as viewed from the group of micro openings 18 and FIG. 3B is a line A- in FIG. It is a vertical side view on A. As is clear from FIG. 3, the light focusing element section 15 has a conical shape in which the optical path cross-sectional area gradually decreases from the laser diode array 2 toward the first minute opening 16, but may have a pyramid shape. And the inside is 70 gold
This is a micromirror 15a deposited with a thickness of 00 °.

The light diffusion element 17 is provided with the first minute opening 1.
6 is formed in a hemispherical shape corresponding to the shape of a small integrating sphere such as a sphere, a super hemisphere, and a cone. A group of minute openings 18 is formed at a position opposing to. The group of minute openings 18 has a plurality of second minute openings 19 and 20 that divide the light beam of the beam diffused by the light diffusing element unit 17 into a plurality of spot lights and emit the light. And
The inner surface of the light diffusing element 17 has a light diffusing surface 17a formed by depositing gold with a thickness of 7000 °.

The plurality of laser diodes of the laser diode array 2 are 42.3 μm corresponding to 600 dpi.
In accordance with this, the arrangement pitch of the light focusing element section 15, the first opening section 16, the light diffusion element section 17, and the minute opening group 18 is 4 at the center distance.
It is set to 2.3 μm.

As shown in FIG. 3, in the present embodiment in which the diameter of the second minute opening 19 arranged in the center is large and the diameter of the second minute opening 20 arranged in the periphery is small. The above-mentioned light intensity control means is provided on the image carrier 10.
For a pixel to which a large amount of exposure is to be given in a region corresponding to the pixel, the bright spots of the beams from the second minute openings 19 and 20 have a light intensity density equal to or higher than a threshold value, and the second openings 19 and 20 The light intensity is set to such an extent that the same number of dot-shaped photosensitive areas are formed. For pixels to which a lower exposure dose is to be given, the light intensity is reduced in accordance with the degree, thereby reducing the area of the light intensity density equal to or higher than the threshold value of each luminescent spot to reduce the area of each dot-shaped photosensitive area. The area is reduced. For a pixel to which a lower exposure dose is to be applied, the light intensity is further reduced in accordance with the degree, so that the number of luminescent spots reaching a light intensity density equal to or higher than the threshold value is gradually reduced and formed on the image carrier 10. The number of dot-shaped photosensitive areas is reduced.

The changes that occur in the pixels formed due to the difference in the light amount setting described above will be described with reference to FIGS. FIG. 4A shows the relationship between the light level and the light level on the image carrier 10 on the line AA in FIG. 3 when the light intensity is increased in the case of a pixel giving a large amount of exposure. Graph,
FIG. 2B is an explanatory diagram showing a pattern of pixels exposed on the image carrier 10. FIG. 5A shows the relationship between the photosensitive level on the image carrier 10 and the light amount density on the line AA in FIG. 3 when the light intensity is reduced in the case of the pixel giving the lowest exposure amount. FIG. 3B is a diagram illustrating a pattern of pixels exposed on the image carrier 10.

As described above, the image writing apparatus 1 according to the present embodiment uses the characteristic that the image carrier 10 is generally exposed when it receives an exposure amount equal to or more than a certain threshold.
In order to control the size and number of minute photosensitive areas by changing the light intensity of the beam, a change in optical density or light sensitivity with respect to the exposure amount of the image carrier 10, that is, a so-called gamma characteristic has a sharp rise at a certain exposure amount. It is desirable that the properties have the following. The image carrier (photoconductor) 10 in an electrophotographic image output device generally has such photosensitive characteristics, and is an image recording medium suitable as an object of the image writing device 1 of the present invention.

Conventionally, an image carrier having a steep gamma characteristic has been regarded as not suitable for writing a halftone image having a smooth density gradation. However, in the present invention, the steepness which has been regarded as a disadvantage in the prior art is considered. By utilizing the gamma characteristic, it is possible to reproduce a smooth halftone to the extent that was difficult with the conventional method.

In FIGS. 3 to 5, the second minute openings 19 and 20 have been described with a simple arrangement pattern. However, optical writing for optical writing arranged at a pitch of 600 dpi which is a normal resolution is performed. When a light source is used, the width of one pixel region is about 42.3 μm, and it is not difficult to make the diameter of the second minute openings 19 and 20 about 1 μm. Therefore, a large number of second minute openings 19 and 20 such as 4800 are provided in one pixel region.
Since about 10 to 20 second minute openings 19 and 20 each having a diameter of 5 μm corresponding to a writing spot of dpi can be provided, it is possible to generate a halftone image having a fine screen pattern that cannot be visually recognized. It can be perceived by a viewer of the image as a smooth halftone.

As described above, although each pixel is written as an aggregate of fine photosensitive areas, its average density can be controlled simply by changing the light source light amount, so that an apparently smooth halftone image is obtained. 600d
Image processing can be performed at a speed as high as a normal resolution of about pi. Therefore, two problems of high-speed image output and generation of a smooth halftone image can be solved.

If the light intensity of the laser diode array 2 is sufficiently increased, the small photosensitive areas (the photosensitive areas by the beams passing through the second small openings 19 and 20) included in one pixel are image-bearing. Saturation of the body 10 results in one continuous photosensitive area. Therefore, when writing a simple line drawing that does not require halftone, for example, by increasing the light intensity of the laser diode array 2 to that extent, an image is output by an image writing device having a normal resolution of, for example, about 600 dpi. It can be constant.

However, the image writing device 1 of the present invention
Unlike the case where a screen pattern halftone image is actually written on the image carrier 10 by an image writing device having a fine resolution, a line image cannot be written with a resolution separated by individual spots. This is because pixels formed by the image writing apparatus 1 of the present invention having a normal level of resolution are divided by the micro optical element 3 into small writing spots. However, 600 dpi
Most line drawing images required daily can be reproduced with a resolution of the order. In other words, even if a line drawing is written with a higher resolution, it cannot be recognized by the naked eye as a separate line, and is meaningless except for very special uses.

However, the reason why an image writing device of 600 dpi or more is required is for the case where it is necessary to write the density gradation in a screen pattern which cannot be visually recognized. For this reason, the conventional high-resolution image writing apparatus is required to have a very high-precision creation technique, and is expensive. On the other hand, in the image writing apparatus 1 of the present invention, it is possible to write a screen pattern that has a normal resolution but cannot be visually recognized. , And can be created at low cost, and can reproduce a smooth halftone image which has been impossible in the past while having a normal resolution.

In the above description, it is assumed that the pattern formed by the arrangement of the second minute openings 19 and 20 for generating the halftone of the minute optical element 3 exposes the image carrier 10 at the same magnification. , May be enlarged or reduced by the scanning optical system 11. In this case, the size of this pattern may be changed according to the fineness of the halftone to be created on the image carrier 10 and the magnification of the scanning optical system 11.

Further, even when the diameters of the second openings 19 and 20 are equal to each other and the second openings 19 and 20 are arranged in a matrix, the light intensity of the laser diode array 2 is changed.
A desired halftone image can be reproduced by increasing or decreasing the area of the divided point-shaped photosensitive regions in one pixel region. However, as shown in FIG. 3, the first halftone image disposed at the center of the one-pixel region can be reproduced. A group of minute openings 18 is formed by the two minute openings 19 and one or a plurality of second minute openings 20 arranged around the second minute openings 19. By defining the diameters of the portions 19 and 20 to be smaller than those arranged from the center of the one-pixel region toward the periphery, the size of a plurality of dots forming one pixel is large at the center and large at the periphery. Since it is smaller, the average density change in the image area becomes smooth. In addition, when the light intensity of the beam is reduced, the number of dots can be reduced because dots cannot be formed from the small second peripheral small openings as shown in FIG. As a result, a smoother halftone can be reproduced.

As a member for converging the beam emitted from the laser diode array 2, almost any member having a light converging function can be used. For example,
There is a so-called microlens that focuses a beam by a refractive index distribution. However, although this element has a tentative light focusing function, its manufacturing method is special, and the manufacturing process for integration is complicated. On the other hand, the light focusing element section 15 in the present embodiment has a conical shape (the same applies to a pyramid shape) in which the optical path cross-sectional area gradually decreases from the laser diode array 2 side toward the first minute opening 16. The inner surface is a micromirror 15a, and has a structure in which a first opening 16 is arranged on the emission side. The advantage of this structure is that the manufacturing equipment and manufacturing process used for manufacturing semiconductors and the like can be applied in the manufacturing thereof.
The highly accurate light focusing element section 15 can be manufactured at a low cost by a simple method.

Further, as the element for diffusing the beam emitted from the laser diode array 2, any element having a light diffusion function can be used. For example, a so-called opal glass plate containing a large number of fine particles that disperse light can be cited. However, this element has a large light absorption amount in light diffusion, and the energy of the laser diode array 2 cannot be used effectively. In addition, since the manufacturing method is special, the manufacturing process for integration is complicated.
On the other hand, the light diffusion element section 17 has a shape of a minute integrating sphere having a hemispherical shape (the same applies to a spherical shape, a super-hemispherical shape, and a conical shape), and faces the first minute opening portion 16 on the integrating sphere. This is a structure in which the small opening group 18 is arranged at a position where the small opening portion 18 is located. The advantage of this structure is that the manufacturing equipment and the manufacturing process used for manufacturing semiconductors and the like can be applied in the manufacture thereof, so that the highly accurate light diffusion element section 17 and the group of minute openings 18 can be manufactured at a low cost by a simple method. Can be manufactured. Furthermore, the amount of light absorption is smaller than that of an opal glass plate, and the energy of the laser diode array 2 can be used effectively.

Further, a microlens (not shown) is formed on at least one of the opening surface of the first minute opening 16 and the opening surface of the minute opening group 18. Is also good. By doing so, the light use efficiency is increased, and the image writing speed can be increased.

The image recording medium to which the image writing apparatus 1 of the present invention writes an image includes a rewritable recording medium, a recording medium that cannot be rewritten once recorded, and an image display device to which an image is continuously written as needed. Most of the media on which images are formed by optical writing, including such media.

Specific examples thereof include: Visible light, ultraviolet or infrared radiation or specific temperature change, application of an electric or magnetic field, etc., caused by a phase change of the display material, a change in crystalline state, other state change, or a generally reversible chemical change,
A visible image is formed by changing the light transmittance, light scattering state, spectral reflectance, refractive index, birefringence, etc. of the display material, and irradiating light of a specific wavelength and intensity as necessary 1. An image recording medium called a digital paper which can be repeatedly used by applying an electric field or a magnetic field of a specific intensity and direction, or by applying a specific temperature change, and can be used repeatedly. 2. Electrophotoreceptor 3. Black-and-white and color films or photosensitive paper by silver halide photography. 4. Other recording media using a photosensitive material by a photochemical reaction; A photoconductive material layer is disposed between the liquid crystal material layer and the driving electrode, and the irradiation of the photoconductive material layer with the writing light causes the photoconductive material at that portion to be in a conductive state so that an electric field is partially applied to the liquid crystal layer. Such as a liquid crystal display of a type in which an image is written in the form of an image, and a display in which an image having a change in density is formed immediately by using the photoconductive effect or the like.

The image writing apparatus 1 of the present invention can write a smooth halftone image on all the image recording media with an inexpensive configuration.

Next, an electrophotographic image output apparatus equipped with the above-described image writing apparatus 1 will be described. An electrophotographic image output device includes an image carrier 10 having photosensitive characteristics (see FIG. 1), an image writing device 1 shown in FIG. 1, and a developing device for developing an electrostatic latent image written on the image carrier 10. The apparatus includes a device (not shown) and a transfer device that transfers a toner image developed on the image carrier 10 to a sheet.

In the image output device having such a configuration,
Since the image writing of the image writing device 1 to the image carrier 10 is as described above, it is possible to reproduce a smooth halftone without increasing the resolution more than necessary, and it is possible to output an image at a high speed. An image output device can be provided.

An electrostatic latent image of a different color is formed on the image carrier 1.
In the case of an image output device for a color image provided with a plurality of the image writing devices 1 in order to write 0, the micro optical element 3 of the image writing device 1 outputs the beam emitted from the second minute opening. The position of the second minute opening or the inclination angle of the optical path is changed so that the irradiation position on the image carrier 10 does not overlap between the colors. In this example, all the second minute openings have the same diameter, and therefore, the same reference numeral 19 will be used for the description.

FIGS. 6A, 6B, 6C, and 6D show an arrangement pattern of the second minute openings 19 for each of the plurality of image writing apparatuses 1 for writing images of different colors. As can be seen from these figures, the second minute apertures 19 are arranged such that the irradiation positions of the emitted beams on the image carrier 10 do not overlap between the colors.

Therefore, when a color image is output, overlapping of dots of each color can be prevented, so that an image without color turbidity can be output. As described above, by changing the light intensity of the beam emitted from the laser diode array 2, a smooth halftone can be reproduced without increasing the resolution more than necessary.

FIGS. 7 (a), 7 (b), 7 (c) and 7 (d) are different only in that the number of arrangements of the second minute openings 19 is increased and the arrangement pattern is changed. The same is true. In the case of FIG. 6, the number of arrangement of the second minute openings 19 is small, so that the manufacture is easy. In the case of FIG. 7, since the number of arrangements of the second minute openings 19 is large, the production cost is increased as compared with FIG. 6, but a smoother halftone image can be reproduced.

Next, a method of manufacturing the micro optical element 3 will be described with reference to FIGS.

First, the procedure for manufacturing the light focusing element section 15 will be described. A first substrate 13 prepared by polishing a quartz glass substrate to a thickness of 40 μm is prepared, and one surface of the first substrate 13 opposite to the laser diode array 2 is bonded to a glass plate (not shown) having a good flatness with a thermoplastic resin. Attached, first substrate 1
A positive photoresist is applied to the other surface of the third laser diode array 2 side. The positive photoresist is OFPR8600 (viscosity 80) manufactured by Tokyo Ohka Kogyo Co., Ltd.
(cps) using a spin coating method so as to have a thickness of 3 μm.

Next, this photoresist film is heated at 90 ° C. 30
After baking under the conditions of 20 minutes, the photoresist film is exposed through a mask in which five circular openings having a diameter of 20 μm are linearly arranged at a pitch of 42.3 μm through five masks. A post-bake process is performed to pattern a resist mask having the same shape as the mask.

In this state, the first substrate 13 is etched in a buffered hydrofluoric acid solution. The etching time was determined by observing the point in time when the first substrate 13 made of quartz glass penetrated and the first minute opening 16 was formed on the surface opposite to the resist mask, and the diameter became 5 μm. The first opening 16 opened on the bottom surface can be easily distinguished from the portion where the first substrate 13 exists by being exposed on the glass plate, and the diameter of the first opening 16 can be determined with a microscope. It can be easily measured. By utilizing the fact that the diameter on the side opposite to the first opening 16 is larger than that of the resist mask due to the undercut, the diameter is 40 μm and the first opening 16 on the opposite side is used.
An aperture having a conical shape with a diameter of 5 μm, that is, an array in which the light focusing element portions 15 are linearly arranged at a pitch of 42.3 μm can be obtained.

In this case, the conical shape can be controlled by adjusting the temperature of the etching solution, the concentration of hydrofluoric acid, and the frequency of stirring.

Next, the first substrate 1 is placed on a glass plate serving as a base.
The etching mask is removed by oxygen plasma ashing with 3 still attached, and gold is deposited to a thickness of 7000 mm on the inner surface of the light focusing element portion by a vacuum deposition device to form a micro mirror 15a.

After that, the glass plate is heated and the first substrate 1 is heated.
3 is removed and washed with an organic solvent to remove the thermoplastic resin used for pasting.

The first substrate 13 on which the micromirrors 15a are formed is aligned with the center of the light focusing element section 15 and the center of the laser diode of the laser diode array 2, and the laser diode array 2 is formed of a thermosetting resin. Is to be adhered to.

Next, the procedure for manufacturing the light diffusion element section 17 will be described. A second substrate 14 prepared by polishing a quartz glass substrate to a thickness of 40 μm is prepared, and one surface of the second substrate 14 is attached to a silicon wafer (not shown) having good flatness with a thermoplastic resin, A positive photoresist is applied to the second substrate 14 on the side opposite to the silicon wafer.
This photoresist is OFPR8 manufactured by Tokyo Ohka Kogyo Co., Ltd.
Using 600 (viscosity: 80 cps), coating is performed by spin coating so as to have a thickness of 3 μm.

An opening group in which openings having a diameter of 3 μm (corresponding to the second openings 19 and 20) are arranged in a pattern similar to the pattern shown in FIG. That is, exposure is performed through a mask that is repeatedly formed linearly at 600 dpi, and a normal prebaking, developing, rinsing, and postbaking process is performed to form a resist mask having the same shape as the mask.

Next, the second substrate 14 is etched in a dilute hydrofluoric acid solution with the silicon wafer attached.
The etching time is 2 μm for the second substrate 14 made of quartz glass.
Is the time to be etched to a depth of. This 2 μm is
One surface of the second substrate 14 corresponds to the depth of the second minute openings 19 and 20.

Thereafter, the silicon wafer is heated to remove the second substrate 14 and washed with an organic solvent to remove the thermoplastic resin used for the attachment.

Next, the second substrate 14 is turned over, and the surface on the opposite side is attached to a silicon wafer (not shown) having good flatness with a thermoplastic resin, and the surface from which the silicon wafer has been peeled off, ie, A photoresist is applied to a surface on which a 2 μm concave portion corresponding to the two openings 19 and 20 is formed. This photoresist is OFP manufactured by Tokyo Ohka Kogyo Co., Ltd.
R8600 (viscosity: 80 cps) is applied by spin coating to a thickness of 3 μm.

This photoresist was used to form circular openings having a diameter of 20 μm at a pitch of 42.3 μm, ie, 6 μm.
Exposure is performed through a mask arranged on a straight line at 00 dpi, and normal development, rinsing, and post-baking steps are performed to form a resist mask having the same shape as the mask.

In this state, the second substrate 14 is immersed in a dilute hydrofluoric acid solution and etched. The etching time is such that the second substrate 14 made of quartz glass has a concave portion dug by etching and the second opening 1 dug by the previous etching.
Depressions corresponding to 9 and 20 appear, and they are determined by observing the points at which they penetrate the depressions dug out this time. The shape of the dug recess is controlled by adjusting the etchant, temperature, hydrofluoric acid concentration and the frequency of stirring. The recess dug out this time is etched by undercut until it becomes a recess having a shape close to a hemisphere with a diameter of 40 μm on the opening side. One of the penetrating concave portions is the light diffusion element portion 17, and the other concave portion is a plurality of second opening portions 19 and 20 forming the minute opening group 18.
It is.

Next, the etching mask is removed while being attached to the silicon wafer, and gold is vapor-deposited on the inner surface of the light diffusion element portion 17 of the second substrate 14 to a thickness of 7000 ° to form the light diffusion surface 17a. To form At this time, it is preferable to slightly supply argon gas into the vacuum chamber to increase the pressure at the time of vapor deposition so that the surface of the vapor-deposited gold has a satin shape suitable for diffusing light.

Thereafter, the silicon wafer is heated to remove the second substrate 14, washed with an organic solvent to remove the thermoplastic resin used for bonding, and
Then, an array of the light diffusing element sections 17 provided with the light emitting elements 8 is formed.

Then, the centers of the first opening 16 and the minute opening group 18 are made to coincide with each other, and the substrates 13 and 14 are adhered to each other with a thermosetting resin, thereby forming the micro optical element 3.

By manufacturing the micro optical element 3 by such a method, the center of gravity of the first micro opening 16, the light diffusing element section 17, and the center of the micro opening group 18 can be easily matched. Further, the thickness around the small opening group 18 arranged at the center of the light diffusion element section 17 becomes thin, but the second substrate 14 before the light diffusion element section 17 is dug is thickened. By digging the concave portions corresponding to the minute openings 19 and 20, it is possible to prevent the second substrate 14 from being damaged in the manufacturing process and improve the yield.

[0078]

According to the first aspect of the present invention, as described above, a plurality of second minute light beams that divide a light beam of a beam emitted from a light source in a unit of one pixel into a plurality of spot lights and emit the plurality of spot lights are provided. Since the aperture is provided with a micro optical element having a group of micro apertures arranged in the same plane and light intensity control means for increasing or decreasing the intensity of the beam emitted from the light source according to the halftone to be reproduced, By increasing or decreasing the light intensity, it is possible to increase or decrease the size of a plurality of dots forming one pixel on the image recording medium, and therefore, it is possible to reproduce a smooth halftone without increasing the resolution more than necessary. it can. Further, since it is not necessary to increase the resolution more than necessary, an image can be output at a high speed.

According to a second aspect of the present invention, in the image writing apparatus according to the first aspect, the minute opening group includes a second minute opening disposed at the center of the one-pixel area, and the one-pixel area. And one or more second minute openings arranged around the second minute opening arranged at the center of the pixel, and the diameter of the second minute opening is the center of the area of one pixel. Since the diameter of the second minute opening located closer to the periphery is smaller than that of the second opening, the size of a plurality of dots forming one pixel is larger in the center and smaller in the periphery, so that the image area The average density change at In addition, when the light intensity of the beam is reduced, by suppressing the formation of dots from the small second small openings in the periphery and reducing the number of dots, a smoother halftone image can be reproduced. .

According to a third aspect of the present invention, in the image writing apparatus according to the first or second aspect, the light focusing element portion of the micro optical element has an optical path cross-sectional area gradually increasing from the light source side to the first micro opening. Since the inner surface of the pyramidal or conical shape that becomes smaller is formed by the micromirror,
A high-precision light focusing element can be manufactured by a simple method by applying manufacturing equipment and a manufacturing process used for manufacturing a semiconductor or the like.

The invention described in claim 4 is the first to third aspects of the present invention.
In the image writing device according to any one of the above, the light diffusing element portion of the micro optical system has a shape of a minute integrating sphere such as a spherical shape, a hemispherical shape, a hyper hemispherical shape, and a conical shape. Since the aperture group is arranged, by applying the manufacturing equipment and manufacturing process used for manufacturing semiconductors, etc., a high-precision light-diffusing element section that has a small light absorption amount and can effectively use the energy of the light source light It can be manufactured by a simple method.

The fifth aspect of the present invention provides the first to fourth aspects.
In the image writing device according to any one of the above, by forming a microlens on at least one of the opening surface of the first minute opening of the minute optical element and the opening surface of the minute opening group. Thus, the light use efficiency can be increased, and the image writing speed can be increased.

According to a sixth aspect of the present invention, there is provided the image output device according to any one of the first to fifth aspects for writing an electrostatic latent image on an image carrier. It is possible to provide an image output device that can reproduce smooth halftones without any problem and can output images at high speed.

According to a seventh aspect of the present invention, there is provided an image output apparatus comprising a plurality of the image writing apparatuses according to any one of the first to fifth aspects for writing electrostatic latent images of different colors on an image carrier. The micro optical element of the apparatus changes the position of the second micro opening or the inclination angle of the optical path so that the irradiation position of the beam emitted from the second micro opening on the image carrier does not overlap between the colors. It is possible to reproduce smooth halftones without increasing the resolution more than necessary, output images at high speed, and when outputting color images, Therefore, it is possible to provide an image output device capable of outputting an image without color turbidity because it is possible to prevent the overlapping of images.

According to the method of manufacturing a micro optical element in the image writing apparatus according to the present invention, the center of gravity of the first micro opening, the light diffusing element, and the group of micro openings can be easily matched. The thickness around the small opening group arranged at the center of the light diffusion element portion becomes thinner, but the second substrate before the light diffusion element portion is dug, and the concave portion corresponding to the small opening is dug when the second substrate is thick. By doing so, it is possible to prevent the second substrate from being damaged during the manufacturing process and improve the yield.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic configuration of an image writing device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a micro optical element in a cross section together with a light source.

3A and 3B are enlarged views showing a part of the configuration of the micro optical element, wherein FIG. 3A is a front view as viewed from a side of a group of micro apertures, and FIG. 3B is a longitudinal section on line AA of FIG. It is a side view.

FIG. 4 (a) shows the relationship between the light-sensitive density and the light-sensitive density on the image carrier on line AA in FIG. 3 when the light intensity is increased in the case of a pixel giving a large amount of exposure. FIG. 4B is a diagram illustrating a pattern of pixels exposed on the image carrier.

FIG. 5A is a graph showing the relationship between the light-sensitive density and the light-sensitive density on the image carrier along line AA in FIG. 3 when the light intensity is reduced in the case of a pixel providing the lowest exposure amount. FIG. 4B is a diagram illustrating a pattern of pixels exposed on the image carrier.

FIG. 6 is an explanatory diagram showing an arrangement pattern of second minute openings for each of a plurality of image writing devices that write images of different colors.

FIG. 7 is an explanatory diagram showing an arrangement pattern of second minute openings for each of a plurality of image writing devices that write images of different colors.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image writing apparatus 2 Light source 3 Micro optical element 10 Image recording medium, image carrier 11 Scanning optical system 13 First substrate 14 Second substrate 15 Light focusing element unit 15a Micro mirror 16 First minute opening 17 Light diffusion Element portion 17a Light diffusing surface 18 Small opening group 19, 20 Second minute opening

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C362 AA03 AA07 AA13 AA15 AA33 AA36 BA04 2H097 LA17 5C074 AA02 AA12 BB03 CC22 CC26 DD08 EE11 FF05 GG03 GG04 GG07 GG09 5F073 AB02 AB29 BA07 GA02 GA12

Claims (8)

[Claims] 1. A light converging element section for converging a light beam of a beam emitted from a light source in a unit of one pixel, and a first minute aperture disposed at a position where the light beam is converged by the light converging element section. A light diffusing element disposed on the emission side of the first minute opening, and a plurality of second minute rays for dividing a light beam of a beam diffused by the light diffusing element into a plurality of spot lights and emitting the light. A micro-optical element having a group of micro-apertures whose apertures are arranged in the same plane; light intensity control means for increasing or decreasing the intensity of a beam emitted from the light source in accordance with a halftone to be reproduced; An image writing apparatus comprising: a scanning optical system that scans a beam emitted from an element onto an image recording medium. 2. The micro-opening group includes a second micro-opening disposed at the center of the one-pixel area and a second micro-opening disposed at the center of the one-pixel area. The second minute opening is formed by one or a plurality of second minute openings arranged, and the diameter of the second minute opening is the second minute opening arranged at a position from the center of the area of one pixel to the periphery. 2. The image writing apparatus according to claim 1, wherein the diameter of the opening is set smaller. 3. The light converging element section has a pyramid-shaped or conical inner surface formed by a micromirror whose optical path cross-sectional area gradually decreases from the light source side toward the first minute aperture. 3. The image writing device according to 1 or 2. 4. The light diffusing element section has a spherical shape, a hemispherical shape, a hyper-hemispherical shape provided corresponding to the first minute opening,
4. The device according to claim 1, which has a shape of a minute integrating sphere such as a conical shape, and wherein the minute opening group is arranged at a position on the integrating sphere opposite to the first minute opening. The image writing device according to claim 1. 5. A microlens is formed on at least one of an opening surface of the first minute opening and an opening surface of the minute opening group.
The image writing device according to any one of the above. 6. An image carrier having photosensitive characteristics, an image writing device according to claim 1, for writing an electrostatic latent image on said image carrier, and an image carrier written on said image carrier. And a transfer device for transferring an image developed on the image carrier to a sheet. 7. An image carrier having photosensitive characteristics, a plurality of image writing devices according to claim 1 for writing electrostatic latent images of different colors on said image carrier, A developing device that develops the electrostatic latent image written on the image carrier for each of different colors; and a transfer device that transfers an image developed on the image carrier to paper, The micro optical element changes the position of the second micro opening or the inclination angle of the optical path so that the irradiation position of the beam emitted from the second micro opening to the image carrier does not overlap between the colors. Image output device. 8. A step of forming the light focusing element portion according to claim 1 or 3 and the first minute opening according to claim 1 or 3 in a first substrate, and one surface of a second substrate. Forming an etching mask having a pattern corresponding to the arrangement of the group of minute openings according to claim 1 or 2; and etching the second substrate to form the group of minute openings on one surface of the substrate. A step of digging a corresponding concave portion; and positioning an etching mask having a pattern corresponding to the arrangement of the light diffusion element portion according to claim 1 or 2 on the other surface of the second substrate in the arrangement pattern of the group of minute openings. Forming together, etching the second substrate and digging a recess corresponding to the light diffusion element portion on one surface of the substrate until the recess penetrates the recess corresponding to the minute opening group. The light diffusing element section and the fine Forming a group of openings in a predetermined shape; forming a light diffusion surface for diffusing light on the inner surface of the light diffusion element; and forming the light focusing element and the first micro opening. Joining the formed first substrate, the group of minute openings, and the second substrate formed with the light diffusing element section to the micro optical element in the image writing apparatus.