JPH0286466A - Lcd printer - Google Patents

Abstract

PURPOSE:To increase the distance between a bar-like light source and LCD and thereby protect LCD against the thermal effects of a light source by providing an optical system which condenses light from each bar-like light source in a vertical direction against the longitudinal direction of the bar-like light source and guides the condensed light to an LCD array. CONSTITUTION:Each one of convergent optical systems 5-1, 5-2, 5-3 installed between bar-like light sources 1-1, 1-2, 1-3 and LCD2 capture the scattered light from the bar-like light sources 1-1, 1-2, 1-3 at a broad opening. This captured light is converged and projected to LCD2. Consequently, the distance between the bar-like light sources 1-1, 1-2, 1-3 and LCD2 can be increased so that the thermal effects of the light sources 1-1, 1-2, 1-3 upon LCD2 are blocked. At the same time, a higher intensity of light can be projected to LCD2 compared to the light intensity when the distance is short, in spite of the fact that the distance is long.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to LCD (Liquid Crystal D
This invention relates to an improvement in the exposure system of a printer using an isplay (liquid crystal display).

(Background of the invention) FIG. 9 shows the configuration of a conventional LCD printer.

Figure (a) is an explanatory view seen from the side, and figure (b) is a front view. The light emitted from the rod-shaped light source 1 illuminates the LCD array 2 almost uniformly.

Each LCD of the LCD array 2 transmits or blocks the light emitted from the rod-shaped light source 1 according to an image signal. That is, it turns on and off the transmission of light.

A SELFOC lens array (SLA) 3 forms an image of the light transmitted through the LCD onto a recording medium 4 .

As the rod-shaped light source 1, a hot cathode tube (fluorescent lamp), a halogen lamp, a cold cathode tube, or the like is often used.

Here, the time during which the LCD is turned on by the image signal is determined so that the amount of light is necessary to obtain the required density on the recording medium. Therefore, if the sensitivity of the recording medium is the same, the higher the intensity of light that reaches the recording medium, the shorter the on time (exposure time) will be, and therefore the higher the speed of recording.

In order to increase the light intensity, it is conceivable to shorten the distance t in FIG. 9(a).

(Problem to be solved by the invention) However, since many light sources are also heat sources, LCD2
There is also a limit to how short the distance t between the bar-shaped light source 1 and the bar-shaped light source 1 can be. The reason for this is that the light transmittance when the LCD is turned on and the light transmittance when it is turned off vary depending on the temperature, which changes the contrast, so the LCD must be protected from the effects of heat from the light source. However, LCD 2 and rod light source 1
This is because there is no heat shield between the two, so the distance between them must be maintained. Therefore, there was a problem in that the recording speed was limited due to thermal problems of the light source.

In view of the above problems, an object of the present invention is to use a rod-shaped light source and an LC light source.
While ensuring sufficient distance between the D array and the LCD to avoid the influence of heat from the light source, multiple rod-shaped light sources are provided, and the rod-shaped light source and LCD
An object of the present invention is to provide an LCD printer that increases the amount of light directed to the LCD array by providing an optical system between the arrays that widely receives diffused light from a rod-shaped light source and converges it onto the LCD array.

(Means for Solving the Problems) The present invention has the following means configuration to achieve the above object.

That is, the LCD 7 printer of the present invention includes an LCD array; a plurality of bar-shaped light sources arranged in parallel; and for each bar-shaped light source, the light from the bar-shaped light sources is focused in a direction perpendicular to the longitudinal direction of the bar-shaped light sources. and an optical system for guiding the light onto the LCD array.

(Function) Hereinafter, the function of the LCD printer of the present invention having the above means configuration will be explained.

In the LCD printer of the present invention, a convergence optical system provided between each of the plurality of bar-shaped light sources and the LCD captures the diffused light from the bar-shaped light sources through a wide aperture, converges it, and irradiates it onto the LCD. Because of this, the distance between the bar-shaped light source and the LCD can be lengthened, and the influence of heat from the light source on the LCD can be prevented, and even if the distance is long, a larger amount of light can be irradiated onto the LCD than when the distance is short. Can be done. This will be explained below with reference to the drawings.

FIG. 8(a) is a diagram illustrating light irradiation when a converging optical system is not used, and FIG. 8(b) is a diagram illustrating light irradiation when a converging optical system consisting of a cylindrical convex lens 5 is used. It is.

In Figure (a), consider the irradiation of light from a portion of the rod-shaped light source 1 that can be considered as a linear light source. tl is from linear light source to LCD2
2r is the diameter of the aperture of the LCD 2.

In this case, the amount of light entering the aperture of LCD2 is r/L
Proportional to s.

On the other hand, in Figure (b), when the radius of the cylindrical convex lens 5 is R1 and the focal length is f, and the distance a and the distance satisfy formula (1) % formula % (1), the amount of light entering the aperture of the LCD 2 is R
・Proportional to (a-f)/(af).

Therefore, if the luminance of the linear light source is the same, the light intensity ratio P on the LCD 2 when using the converging optical system and when not using it becomes P=A/-fv (2>).

The diameter 2r of the LCD aperture is usually 0.1 mm to 0.
05 +u, and the distance t1 between the light source and the LCD is approximately 10
Since it is about mm, the order is 0.01 to O, OO5.

On the other hand, when using a convergent optical system, for example, the radius R of the cylindrical lens is 5 yen, and the focal length f is 15+
+us, a = b = 30 am = Q
, 33, the -f light intensity ratio P depending on the presence or absence of the optical system is P=33 to 66. By further providing a plurality of such optical systems, it is possible to set P to approximately 100. Therefore, the exposure time on the recording medium is approximately 1/
100, the recording time can be significantly shortened. Also, the distance from the light source to the LCD is 10
+a+s vs. 60 mm, so when a converging optical system is used, the effect of thermal radiation is only 1/6 of that without.

As explained above, by using a converging optical system for the rod-shaped light source, it is possible to shorten the recording time and avoid the influence of thermal radiation on the LCD.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a first embodiment of the present invention.

It has three light sources, rod-shaped light sources 1-1 to 1-3, and three cylindrical convex lenses 5-1 to 5-3. That is, the eighth
Three sets of the configuration shown in Figure (b) are used. Reference numeral 6 denotes a diffusion plate that diffuses the light converged from three directions just before the aperture of the LCD 2 to make the light uniform to a certain degree. LCD
The light that has passed through the aperture 2 passes through a selfoc lens array (SLA) 3 and is irradiated onto a recording medium 4.

In addition to the cylindrical convex lens, SL is used as a converging optical system.
A may be used, or a sandwich structure of a transparent material such as glass or acrylic material and a reflective member such as aluminum may be used in combination with a cylindrical convex lens.

FIG. 2 shows an example using SLA, and FIG. 3 shows an example using a combination of a sandwich structure of a transparent body and a reflective member and a cylindrical convex lens.

Figure 4 shows three rod-shaped light sources 1-1.1-2.1-3 connected to R(
The configuration is such that color recording can be performed by corresponding to red), G (green), and B (blue). In this case, since there is only one LCD array 2, color filters 8.9.10 and shutters 7-1.7 corresponding to R, G, and B are provided between each bar-shaped light source and the LCD 2.
-2.7-3 is required. The shutter means may be one that mechanically moves a slit or one that turns on and off a liquid crystal panel (transmissive type).

Alternatively, each rod-shaped light source itself may be turned on and off.

FIG. 5 is a diagram showing a driving sequence in the embodiment of FIG. 4. That is, when the LCD 2 performs exposure using R data, only the shutter 7-1 is turned on (rM), and the G
When performing exposure according to data, only the shutter 7-2 is turned on (litFl), and when performing exposure according to B data, only the shutter 7-3 is turned on (open), so that the recording medium is sequentially exposed according to each color data. will be done.

Similar to FIG. 4, FIG. 6(a) shows three rod-shaped light sources 1-1.
1-2.1-3 corresponds to R, G, and B so that color recording is possible, but the difference from Fig. 4 is that the rod-shaped light source itself is turned on and off without using a shutter. It is. That is, when the LCD 2 is exposed to red data, only the rod-shaped light source 1-1 is turned on, and when the LCD 2 is exposed to G data, only the rod-shaped light source 1-2 is turned on.
When performing an exposure operation using B data, only the rod-shaped light source 1-3 is turned on, and the recording medium is sequentially exposed using each color data.

FIG. 6(b) is an example of an on/off drive circuit for a rod-shaped light source. In the configuration of FIG. 6(a), three on/off drive circuits are used.

FIG. 7 is a diagram showing a driving sequence in the embodiment of FIG. 6.

In addition to the above, it is also possible to provide an infrared cut filter as a means to avoid heat radiation to the LCD. If the converging optical system of the present invention and the infrared cut filter are used in combination, the effect will be further improved.

(Effects of the Invention) As explained above, in the LCD printer of the present invention, the converging optical system provided between each of the plurality of bar-shaped light sources and the LCD captures the diffused light from the bar-shaped light sources with a wide aperture and converges it. Since it is designed to illuminate the LCD, it is possible to use both the rod-shaped light source and the LC.
By increasing the distance from D, it is possible to prevent the influence of heat from the light source on the LCD, and even if the distance is long, a larger amount of light can be irradiated onto the LCD than when the distance is short, and as a result, recording It has the advantage of significantly increasing speed.

[Brief explanation of the drawing]

1 to 4 are diagrams showing the configuration of an embodiment of the present invention, FIG. 5 is a diagram showing a drive sequence of the embodiment of FIG. 4, and FIG.
The figure shows the configuration of another embodiment of the present invention, and FIG.
FIG. 8 is a diagram showing the driving sequence of the embodiment shown in FIG. 8, and FIG. 9 is a diagram explaining that the convergent optical system of the present invention can irradiate a larger amount of light onto the LCD while avoiding the influence of heat from the light source on the LCD. 1 is a configuration diagram of an exposure system of a conventional LCD printer. 1.1-1.1-2.1-3... Rod-shaped light source, 2
...LCD, 3...Selfoc lens array (SLA), 4...recording medium,
5... Cylindrical convex lens, 6...
... Diffusion plate, 7-1.7-2.7-3 ... Shutter, 8 ... Red (R) filter, 9 ...
...Green (G) filter, 10...Blue (B) filter, 11-1.11-2.11-3...
imaging lens.

Claims (1)

[Claims] an LCD array; a plurality of bar-shaped light sources arranged in parallel;
The light from each bar-shaped light source is focused in a direction perpendicular to the longitudinal direction of the bar-shaped light source, and the light from the bar-shaped light source is focused on the LCD.
An LCD printer comprising: a converging optical system for guiding the light onto the array.