JPH052892Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a liquid crystal printer that projects an image on a liquid crystal panel controlled by an external signal onto a photoreceptor and transfers it onto a sheet of paper.

[Background technology and its problems]

With the spread of office automation,
Printers with various mechanisms have been researched and put into practical use. These printers are broadly classified into impact type and non-impact type depending on the printing method. The non-impact type has the advantage of low noise because it does not directly impact the printing paper. and,
Non-impact printers include optical printers, thermal printers, and inkjet printers, but optical printers outperform other printers in terms of printing speed and resolution. This optical printer consists of a printer head that generates a light dot pattern that corresponds to the image to be printed, and an electrophotographic section that receives light from the head and actually prints the image on paper, but it depends on the type of head. They are classified into laser printers, light emitting diode printers, and liquid crystal printers. Among these, laser printers are by far the best in terms of printing speed and are the mainstream in the field of high-speed printers, but recently there has been a large demand for cheaper, medium- and low-speed printers, which have small heads and laser printers. Light-emitting diode printers and liquid crystal printers, which do not require expensive parts like rotating polygon mirrors in printers, are also attracting attention. However, the light emitting diode printer has a problem of low yield of diode arrays, whereas the liquid crystal printer has the advantage of having a simple structure and being easy to use.

However, there is a strong demand for lower cost and higher speed for this liquid crystal printer, and as a cost reduction measure, an organic photoreceptor is used as the photoreceptor that is coated on the surface of the photoreceptor drum. Although this organic photoreceptor is cheaper than conventional inorganic photoreceptors such as amorphous selenium, its sensitivity is low, and therefore the amount of light from the backlight of the liquid crystal panel must be increased.

Conventionally, fluorescent lamps have been used as light sources for backlighting, but in order to prevent organic photoreceptors and speed up printing, it is possible to increase the output of fluorescent lamps and use halogen lamps with a large amount of light. However, in any case, in order to enable high-speed printing with low power consumption, the light from the backlight light source must be used efficiently.

By the way, the image on the liquid crystal panel is projected onto the photoreceptor through a gradient index lens, but the effective angle of incidence θ of the gradient index lens is small, for example, about 9 degrees, and if it is incident from an angle other than this angle, However, that light does not pass through the gradient index lens. Therefore, in order to efficiently utilize the light from the backlight light source, it is necessary to direct this light to the liquid crystal panel at a small angle of incidence θ, and
The light must be focused within a narrow area.

Furthermore, when an incandescent lamp is used as a light source, unevenness in the amount of light in the axial direction is caused by the small effective angle of incidence θ of the gradient index lens and the alternating formation of light-emitting and non-light-emitting parts of the filament. It is necessary to eliminate this and achieve uniform light distribution characteristics.

[Purpose of invention]

Therefore, the present invention aims to increase the output of a backlight light source with a simple structure, condense this light within a narrow range at a small angle of incidence, and utilize the light efficiently while creating a light source with uniform light distribution characteristics. The purpose of this invention is to provide a liquid crystal printer that is capable of high-speed printing at low cost.

[Structure of the idea]

The configuration of the present invention is a liquid crystal printer that illuminates a liquid crystal panel controlled by an external signal from a light source placed behind the liquid crystal panel, and projects the image on the liquid crystal panel onto a photosensitive drum via a gradient index lens. The light source section is characterized by comprising an incandescent light bulb having a single wire filament pulled by a spring, and a condensing mirror behind the incandescent light bulb.

Furthermore, if the LCD panel is placed in a cooling air stream,
It is possible to control the temperature of the liquid crystal panel, which is sensitive to high temperatures, and to operate it accurately.

〔Example〕

FIG. 1 schematically shows the structure of a liquid crystal printer. A photosensitive drum 1 whose surface is coated with an organic photoreceptor
1 is rotatably arranged, and a liquid crystal head 10 is arranged at the top thereof. As will be described later, the liquid crystal head 10 includes a liquid crystal panel, a light source, and a gradient index lens, and images on the liquid crystal panel are projected onto the photosensitive drum 11. This image is then developed by the developing device 12 and advances downward as the photosensitive drum 11 rotates. On the other hand, the photographic paper 13 is conveyed to the lower end of the photosensitive drum 11, the image is transferred onto the photographic paper 13 by the corona converter 14, fixed by the fixing device 17, and then discharged. After the transfer, the photosensitive drum 11 is cleaned by a cleaner 15, and further discharged by a static eliminator 16, and a new image is projected again.

Inside the liquid crystal head 10, as shown in FIG.
The liquid crystal panel 1 is placed, but this is per 1 mm.
It has a high density of 10 dots or more, and is driven by a driving device 2 based on an external signal to form an image.

A light source section 3 is arranged behind the liquid crystal panel 1,
The lamp 4 disposed within this light source section 3 has a rating of
It is a long rod-shaped halogen incandescent light bulb with a tube diameter of 6 mm and is less than 200W. Here, in the lamp 4, as shown in FIG. 3, the filament 41 is a single wire filament, for example, made of a single linear incandescent wire or a plurality of stranded wires made of tungsten, and the light emitting part is non-coiled. . One end of the filament 41 is fixed to the inner conductor 42B, and the other end is fixed to the small diameter portion of the spring 43 and slidably contacts the inner conductor 42A to be electrically connected. and,
The other end of the spring 43 is fixed to the inner conductor 42A, and the filament 41 is installed with an appropriate tension by the spring 43.

A condensing mirror 5 is arranged behind the lamp 4, and the condensing mirror 5 has an elongated elliptical cross section with a large ratio of the major axis to the minor axis. It is located at the first focal point of 5. A filter 7 made of heat-reflecting glass or heat-absorbing glass is arranged in front of the light source section 3.
Although the heat of the lamp 4 is blocked by this, cold air is further blown onto the liquid crystal panel 1 from the cooling fan 8, and the temperature of the liquid crystal panel 1 is controlled to a low temperature by the action of the filter 7 and the cold air. A gradient index lens 9 is arranged in front of the liquid crystal panel 1, and the entrance end surface of the gradient index lens 9 is located at the second focal point of the condenser mirror 5.

When the lamp 4 is turned on, the light passes through the liquid crystal panel 1 and enters the gradient index lens 9 at an incident angle θ, and the image on the liquid crystal panel 1 is projected onto the photosensitive drum 11. At this time, since the filament 41 of the lamp 4 is a single filament, it can be regarded as a linear light source, and since this linear light source is located at the first focal point of the condensing mirror 5, the light has a small incident angle θ and a narrow The light passes through the liquid crystal panel 1 and enters the gradient index lens 9. Since the filament 41 is pulled by the spring 43, its position within the lamp 4 is stable even against vibrations, and even if the filament 41 stretches due to thermal expansion, it is absorbed by the spring 43, so the filament 41 is always located at the first focal point of the condensing mirror 5. Therefore, in combination with the fact that the lamp 4 is an incandescent bulb with a large amount of light, the light from the lamp 4 can be used effectively. In addition, since the filament 41 is a single wire filament and is a uniform light emitter, power consumption is low, and there is no unevenness in the amount of light in the axial direction even if a gradient index lens with a narrow effective incident angle is used. Provides uniform light distribution characteristics.

[Effect of idea]

As explained above, the light source unit of the present invention consists of an incandescent bulb with a single filament pulled by a spring and a condensing mirror behind the incandescent bulb, so it has a simple structure and is a light source for backlighting. This aims to increase the output of the light, condense the light within a narrow range at a small angle of incidence, utilize the light efficiently, and create a light source with uniform light distribution characteristics without unevenness in the amount of light in the axial direction. Therefore, even if an organic photoreceptor with low sensitivity is used as a photoreceptor, the liquid crystal printer can be reliably exposed to light and can perform high-speed printing at low cost.

[Brief explanation of the drawing]

Figure 1 is a schematic explanatory diagram of a liquid crystal printer, Figure 2
The figure is a sectional view of the liquid crystal head, and FIG. 3 is a sectional view of the lamp. 1...Liquid crystal panel, 2...Drive device, 3...Light source section, 4...Lamp, 41...Filament, 4
3... Spring, 5... Focusing mirror, 7... Filter, 8... Cooling fan, 9... Gradient index lens, 10... Liquid crystal head, 11... Photosensitive drum.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. A liquid crystal display that illuminates a liquid crystal panel controlled by an external signal from a light source placed behind the panel and projects an image on the liquid crystal panel onto a photosensitive drum via a gradient index lens. 1. A liquid crystal printer, wherein the light source section comprises an incandescent light bulb having a single filament pulled by a spring, and a condensing mirror behind the incandescent light bulb. 2. The liquid crystal printer according to claim 1, wherein the liquid crystal panel is placed in a cooling air stream.