JPH03271775A - Optical scanner - Google Patents

Abstract

PURPOSE:To surely irradiate photosensitive drum by providing a condensing means consisting of a photosetting resin cured by an outgoing light from an optical waveguide, on each of many liquid crystal shutters. CONSTITUTION:A liquid crystal shutter array 15 is a slender planar liquid crystal panel on which liquid crystal microshutters 12 are arrayed while extending over printing width on one straight line, and the liquid crystal microshutters 12 are opened ad closed, respectively, based on an image signal, and serve as a photomask for emitting a light beam from a light source 11 as optical dot at every one picture element unit. Also, on each of the liquid crystal microshutters 12, a condensing means, that is, a microlens 16 consisting of a photosetting resin cured by the outgoing light from an optical waveguide is provided. In such a manner, a light beam can be condensed exactly onto a photosensitie drum 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical scanning device used in optical printers and 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 print 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.

In addition, if the optical system 34 is not used, the light emitted from the liquid crystal mirror array 33 will be emitted with a certain spread angle, resulting in the problem that adjacent pixels will interfere with each other and the image quality will be extremely degraded. There was a point.

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 an inexpensive and compact optical scanning device that condenses light onto 40.

[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 a light condensing means in each of a large number of minute liquid crystal shutters in an inexpensive and simple manner, and the shape of the condensing means is such that the light is condensed onto the photosensitive drum. Its purpose is to give shape.

[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 performing optical scanning, each of the liquid crystal shutters is provided with a light focusing means made of a photocurable resin cured by the light emitted from the optical waveguide.

[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 hardened by the light emitted from the optical waveguide. Since the light condensing means is made of a photocurable resin, it is possible to provide the light condensing means in an inexpensive and simple manner.At the same time, by controlling the amount of light emitted from the optical waveguide, the light condensing means The shape of the lens can be made into a lens shape that allows light to be accurately focused on the photosensitive drum.

[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.

The microlens element 6 is manufactured on the lower surface of the liquid crystal shutter array 15 by the following manufacturing process.

First, the lower surface of the liquid crystal shutter array 15 is immersed in the photocurable material 51. The photocurable material 51 is, for example, a mixture of an acrylic acid ester polymer (refractive index at the time of curing, n=1.54), which is an ultraviolet light curing resin, and an initiator.

Next, each liquid crystal micro-shutter 12 of the liquid crystal shutter array 15 is kept open only for one pixel forming the microlens 16, and the others are kept closed. Then, the optical fiber 52 is brought into contact with the upper surface of the liquid crystal micro-shutter 12 in the open state, and aligned so that the optical axis of the emitted light from the output end 52a passes through the center of the liquid crystal micro-shutter 12, and The light is made to be incident perpendicularly to the top surface of the shutter 12.

If the above materials are used, the curing light 55 is light emitted from an ultraviolet light source.

The light that has passed through the liquid crystal shutter array 15 is emitted from the lower surface of the liquid crystal shutter array 15.
The optical power density distribution of this emitted light becomes a Gaussian distribution with the apex at the center of the liquid crystal micro-shutter 12. The photocurable material 5 is cured by the curing light propagated by the optical fiber 52.
1 is cured, but since the shape of the cured portion 53 follows the optical power density distribution of the emitted light, it becomes a chevron shape centered on the liquid crystal microshutter 12, as roughly shown in FIG.

For example, when the resolution is 300 dpi, the intensity 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.
In this case, the photocurable material 51 formed the above-mentioned chevron-shaped cured portion 53 after approximately 100 m5ec.

Furthermore, by repeating the manufacturing process using the optical fiber 52 for each pixel, a hardened portion 53 is formed on the entire lower surface of each liquid crystal micro-shutter 12 constituting the liquid crystal shutter array 15.
is formed.

Finally, after curing, the lower surface of the liquid crystal shutter array 15 is taken out from the photocurable material 51, the uncured material is washed, and the light 55 is applied to the liquid crystal shutter array 15 to harden the material again.
By irradiating the entire lower surface of the microlens 16, the microlens 16 is reliably cured. The cleaning method uses ultrasonic cleaning in acetone.

Note that since the photocurable material 51 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 53 formed on the lower surface of the liquid crystal shutter array 15 through the above steps has a lens effect due to the relationship between its shape and refractive index, suppresses the spread of emitted light, and prevents the emitted light from spreading onto the photosensitive drum 20. It has the function of concentrating light.

In particular, since the optical fiber 52 is used when curing the photocurable material 51, the light can be reliably incident on the upper surface of the liquid crystal microshutter 12.

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 20 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, the optical fiber 52 is used as an optical waveguide in order to provide the micro lenses 16 in a large number of minute liquid crystal shutters 12.
The optical axis of the output light passing through 2 passes through the center of the liquid crystal micro-shutter, and is aligned so that it is incident uniformly and perpendicularly to the top surface of the liquid crystal micro-shutter. The cured portion 53 has a chevron shape according to the optical power density, and the light emitted from the liquid crystal shutter 12 does not spread and is reliably irradiated onto the photosensitive drum in a simple manner. Furthermore, it has the effect of being cheaper and more compact than a conventional optical system using a converging 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, the light cured by the light emitted from the optical waveguide is applied to each of the large number of liquid crystal shutters constituting the liquid crystal shutter array. Since a light condensing means made of curable resin is provided,
The light condensing means can be easily provided on a minute liquid crystal shutter, and since an optical waveguide is used, the light emitted from the liquid crystal shutter can be easily placed on the photosensitive drum without spreading the light. This has the effect of allowing the shape to be irradiated with light. 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,
52 is an optical waveguide, and 53 is a light 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 focusing means made of a photocurable resin cured by the light emitted from the optical waveguide.