JPH03271777A - Optical scanner - Google Patents

Abstract

PURPOSE:To surely irradiate a photosensitive drum by providing a condensing means consisting of a photosetting resin cured by a light beam which is allowed to pass through an optical transmission factor distribution mask, on each of many liquid crystal shutters. CONSTITUTION:On each of liquid crystal microshutters 12 corresponding to each picture element of a liquid crystal shutter array 15, a microlens 16 formed by a photosetting resin is provided as a condensing means, and an optical dot emitted by the liquid crystal microshutters 12 by the microlens 16 is condensed onto a photosensitive drum 20. Also, the microlens 16 consists of a photosetting resin cured by a light beam which is allowed to pass through a optical transmission factor distribution mask. In such a manner, an outgoing light is condensed exactly onto the photosensitive drum 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical scanning device used in an optical printer or the like.

[Prior Art] In recent years, optical printers have been used as output devices for computers in place of line printers that have traditionally been used. Among such optical printers, there is a liquid crystal printer that uses a liquid crystal shutter array and an electrophotographic process as technical elements.

Hereinafter, an optical scanning device used in such an optical printer will be explained with reference to FIG.

FIG. 3 shows a conventional optical scanning device 30. As shown in FIG.

In this optical scanning device 30, a rod-shaped light source 3 such as a fluorescent lamp is used.
The light emitted from 1 is irradiated onto a liquid crystal shutter array 33 in which a large number of liquid crystal shutters 35 are arranged over the printing width. Based on the image signal, the liquid crystal shutter array 33 controls the liquid crystal shutter 35 provided for each pixel, thereby generating light from the light source 31 as optical dots for each pixel. For example, in an optical scanning device with a resolution of 300 dpi, the size of one pixel is a square with one side of 85 μm. The optical dots generated on the liquid crystal shutter array 33 are imaged one-to-one on the rotating photosensitive drum 40 by an optical system 34 such as a focusing optical fiber lens array (SELFOC lens array).

Then, exposure is performed line by line sequentially along a straight line parallel to the rotation axis of the photosensitive drum 40. This is called a line scanning exposure method.

In addition, in this line scanning exposure method, in order to avoid using the optical system 34, the liquid crystal shutter array 33 is attached to the photosensitive drum 40.
There was also a method of installing it in close proximity to the

However, the line scanning exposure method described above requires the use of an optical system such as a focusing optical fiber lens array.
There were problems in that it was expensive and the equipment was large.

Furthermore, if the optical system 34 is not used, the light emitted from the liquid crystal shutter array 33 will be emitted with a certain spread angle, which will cause the problem that adjacent pixels will interfere with each other and the image quality will be extremely degraded. there were.

Therefore, as described above, there is a method of installing the liquid crystal shutter array 33 in close contact with the photosensitive drum 40, but in this case, the liquid crystal shutter array 33 is smudged by the toner on the photosensitive drum 40, which also reduces the image quality. This caused the

Therefore, by providing a light condensing means in each of the liquid crystal shutters 35 constituting the liquid crystal shutter array 33, the light emitted from the liquid crystal shutter array 33 can be accurately directed to the photosensitive drum without using an optical system such as a focusing optical fiber lens array. It was conceived to provide a t4 scanning device that focuses light on a 40-meter beam and is inexpensive and compact.

[Problems to be Solved by the Invention] However, the liquid crystal shutters 35 described above are extremely small, and it is difficult to attach a light condensing means, such as a lens, to each of the liquid crystal shutters 35. Further, the condensing means must function to accurately condense the light emitted from the liquid crystal shutter array 33 onto the photosensitive drum 40, and its shape is a problem.

In order to solve the above-mentioned problems, the present invention provides accurate light condensing means for each of a large number of minute liquid crystal shutters, and also makes the shape of the condensing means such that it condenses light onto the photosensitive drum. is its purpose.

[Means for Solving the Problems] An optical scanning device of the present invention includes a light source that emits light and a liquid crystal shutter array configured by arranging a large number of liquid crystal shutters, and controls the liquid crystal shutters based on an image signal. In the optical scanning device that performs optical scanning by doing this, each of the liquid crystal shutters is provided with a condensing means made of a photocurable resin that is cured by light that has passed through a light transmission heavy distribution mask.

[Function] In the present invention having the above configuration, the light emitted from the light source is emitted from the liquid crystal shutter array based on an image signal, and each of the liquid crystal shutters is made to pass through a light transmission heavy distribution mask. Since the light condensing means made of a photocurable resin cured by light is provided, the emitted light is accurately focused onto the photosensitive drum by the condensing means.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

As shown in FIG. 1, the optical scanning device 10 includes a fluorescent lamp 11 as a light source, a liquid crystal shutter array 15 in which a large number of liquid crystal micro shutters 12 are arranged corresponding to each pixel based on an image signal, It includes a condensing means 16 for condensing the light dots emitted from the liquid crystal shutter array 15 onto the photosensitive drum 20 and a dustproof glass 14 .

The fluorescent lamp 11 is a monochromatic aperture type fluorescent lamp that is always lit and has a uniform amount of light, and is lit at a high frequency.

The liquid crystal shutter array 15 is a liquid crystal panel on a long and narrow plate in which liquid crystal microshutters 12 are arranged in a straight line across the printing width. The liquid crystal micro-shutters 12 are opened and closed based on image signals, and serve as a light mask that emits light from the light source 11 as light dots in units of pixels.

Each of the liquid crystal microshutters 12 corresponding to each pixel of the liquid crystal shutter array 15 is provided with a microlens 16 formed of a photocuring resin as a light collecting means. The light dots emitted by the photosensitive drum 20 are focused on the photosensitive drum 20.

The dustproof glass 14 is made of a thin glass plate, and the photosensitive drum 2
It is used to prevent toner from being mixed in from scratch.

FIG. 2 is a schematic diagram showing a method of manufacturing the microlens 16.

Here, a method for manufacturing the microlens 16 will be explained.

First, the lower surface of the liquid crystal shutter array 15 is immersed in the photocurable material 21. This photocurable material 21 is
For example, an initiator is mixed with an acrylic acid ester polymer (refractive index when cured, n=about 1.54), which is an ultraviolet light-curable resin.

Next, all the liquid crystal micro shutters 12 of the liquid crystal shutter array 15 are kept open, and the photocurable material 21
The curing light 25 for curing the liquid crystal shutter array 15
Light transmission heavy distribution mask 2 precisely aligned on the top surface of
2, the light enters the upper surface of the liquid crystal shutter array 15 perpendicularly and uniformly. The light transmission heavy distribution mask 22 is made by distributing the light transmittance using a method such as photolithography so that the optical power density distribution of the transmitted light is approximately Gaussian distributed in a range corresponding to one pixel. . Further, the curing light 25 is light from an ultraviolet light source when the above-mentioned materials are used.

The light that has passed through the light transmission heavy distribution mask 22 and the liquid crystal shutter array 15 is transmitted to the liquid crystal shutter array 15.
The light power density distribution of this emitted light beam becomes a Gaussian distribution with the apex approximately at the center of each liquid crystal micro-shutter 12 due to the effect of the light transmission heavy distribution mask 22. Therefore, since the degree to which the photocurable material 21 is cured depends on the power density distribution, the shape of the cured portion 23 becomes a chevron shape centered on the liquid crystal micro-shutter 12, as roughly shown in FIG.

For example, if the power of the ultraviolet light that has passed through the liquid crystal micro-shutter 12 (open state) is 300 μW at a wavelength of 360 nm for one pixel when the resolution is 300 dpi, the photocurable material 21 is approximately 100 m5ec as described above. The hardened portion 23 has a chevron shape.

Finally, after curing, the lower surface of the liquid crystal shutter array 15 is taken out from the photocurable material 21, the uncured material is washed, and the entire curing part 23 is irradiated with light that hardens the material again to ensure that it is hardened. A microlens 16 is formed. The cleaning method uses ultrasonic cleaning in acetone.

Note that since the photocurable material 21 described above does not harden when it comes into contact with oxygen, it is necessary to carry out the above manufacturing process in a nitrogen atmosphere or the like.

The hardened portion 23 formed on the lower surface of the liquid crystal shutter array 15 through the above process has a lens effect due to the relationship between its shape and refractive index, suppresses the spread of the emitted light, and accurately places the light on the photosensitive drum 20. It has the function of concentrating light.

Next, the operation of such an optical scanning device 10 will be explained using FIG. 1.

The light emitted from the light source 11 passes through the liquid crystal shutter array 15.
The entire top surface is always uniformly irradiated. The opening and closing of each liquid crystal micro-shutter 12 constituting the liquid crystal shutter array 15 is controlled based on the image signal, and light is emitted from the liquid crystal micro-shutter 12 pixel by pixel as a light dot corresponding to an image. At this time, the spread of the emitted light dots is suppressed by the microlens 16 formed by the manufacturing process described above, and the light is focused onto the photosensitive drum 20.

Through the above-described operations, the optical dots are sequentially exposed on the photosensitive drum 2o at a uniform speed in dot line units, thereby recording an image. Each time one line of optical scanning is completed, the photosensitive drum 20 is rotated by a drive source (not shown), and optical scanning is performed by repeating optical line scanning.

As explained above, in this embodiment, in order to provide the microlenses 16 on a large number of minute liquid crystal shutters 12, a method was adopted in which the photocurable resin was cured by the light that passed through the light transmission heavy distribution mask 22. Therefore, the microlens 16 can be easily attached to a minute liquid crystal shutter, and since the shape of the microlens 16 is chevron-shaped, the light emitted from the liquid crystal shutter 12 does not spread and is securely attached to the photosensitive drum. irradiated on top.

Furthermore, it has the effect of being cheaper and more compact than a conventional optical system using a convergent optical fiber lens array or the like.

[Effects of the Invention] As is clear from the detailed description above, according to the optical scanning device of the present invention, each of the large number of liquid crystal shutters constituting the liquid crystal shutter array is illuminated by light that has passed through the light transmission distribution mask. Since the light condensing means made of a hardened photocurable resin is provided, the light condensing means can be provided on a minute liquid crystal shutter, and the light condensing means does not spread the light emitted from the liquid crystal shutter. This has the effect of ensuring that the photosensitive drum is irradiated. Furthermore, there is also the effect that the entire device can be made smaller at a lower cost.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of an optical scanning device according to an embodiment of the present invention, FIG. 2 is a diagram for explaining a method of manufacturing the same microlens, and FIG. 3 is a schematic sectional view of a conventional optical scanning device. It is. In the figure, 10 is an optical scanning device, 11 is a light source, 12 is a liquid crystal shutter, 15 is a liquid crystal shutter array, 20 is a photoreceptor,
22 is a light transmission distribution mask, and 23 is a condensing means.

Claims (1)

[Claims] 1. Optical scanning comprising a light source that emits light and a liquid crystal shutter array configured by arranging a large number of liquid crystal shutters, and performing optical scanning by controlling the liquid crystal shutters based on image signals. An optical scanning device, characterized in that each of the liquid crystal shutters is provided with a light condensing means made of a photocurable resin cured by light passed through a light transmittance distribution mask.