JPH0297918A - Image display device - Google Patents

Abstract

PURPOSE:To obtain the inexpensive and large-sized display which is simple in constitution by providing a colored surface to the rear surface of a transparent sheet the front surface of which is subjected to a rugged treatment and making image display according to the presence or absence of the liquid sticking to the rugged surface. CONSTITUTION:The front surface of the transparent sheet 1 consisting of a flexible acrylic resin, etc., is treated to be formed with very small ruggedness of several mu to several mm and the colored surface 2 is disposed on the rear surface thereof. The colored surface 2 is usually not displayed on the front surface by the light scattering of the front surface of the sheet. The surfaces of the rugged parts are, however, smoothed and the light scattering therein is lost when a very small liquid 3 such as glycerol having nearly the same light refractive index as the light refractive index of the sheet 1 is stuck to the sheet4 1. The colored surface 2 of the lower layer is thus displayed on the front surface. Erasure of the display is executed simply by absorbing away the liquid 3 by an absorber 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a writable and erasable image display device.

[Prior Art] Conventionally, various systems have been devised as large-sized display devices. That is, there are those that use light-emitting elements such as LEDs, those that display different colored surfaces using magnetic force, and those that utilize chemical color changes.

Each of these has different characteristics, and the current situation is to select the most suitable method depending on the application.

On the other hand, for small-sized displays, plasma displays and liquid crystal displays are common.

[Problems to be Solved by the Invention] However, the conventional technology has problems such as a relatively complicated structure and high manufacturing and maintenance costs.

The present invention attempts to solve these problems. That is, an object of the present invention is to provide an image display device that is simple, inexpensive, and requires little maintenance.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a recording member as an optical element provided with an uneven treatment on one surface, and a monochromatic recording member provided close to the other surface of the recording member. Alternatively, the image display device has a recording member colored in a plurality of colors, and a recording writing section for depositing a liquid on one surface of the recording member, and the optical refractive index of the liquid is the same as that of the recording member. The refractive index is equal to or close to the refractive index, and the recording member as one or more optical elements is made to correspond to one pixel, and the interior of the recording member is determined by the presence or absence of liquid adhesion on one surface of the recording member. The image is displayed by controlling the on/off of total reflection of light.

[Function] According to the present invention, since the liquid adhesion of the transparent recording member whose surface has been treated with irregularities is utilized, it is very easy to form and erase images, and the structure is also simple. Therefore, it is cheap.

[Example] FIG. 1 shows a first embodiment of the invention.

In FIG. 1, 1 is a transparent sheet which is a recording member as an optical element, 2 is a colored surface of a colored member, 3 is a liquid,
4 is an inkjet device, 5 is an absorber, and 6 is a conveyance roller for the transparent sheet 1.

That is, the transparent sheet 1 made of flexible acrylic resin or the like moves the display surface as the conveying roller 6 rotates. Further, a colored surface 2 is arranged behind the sheet 1.

The surface of the transparent sheet 1 is treated with minute irregularities of several microns to several am, and normally, due to light scattering on the surface, the colored surface 2 behind it is not displayed in the front. ing. Note that in order to reduce the influence of gravity, the hole diameter is preferably several hundred microns or less.

Here, the inkjet device 4 has a recording width on the surface of the transparent sheet 1 corresponding to the width of the sheet 1 (with respect to the conveyance roller 6).
As a result, minute droplets of glycerin or the like are deposited as a liquid 3 over the width of the sheet 1.

Here, to simplify the explanation, it is assumed that the optical refractive index of the liquid 3 formed by the droplets is equal to the optical refractive index of the transparent sheet 1, and that it does not easily volatilize at room temperature.

The attached liquid 3 fills the concave portions of the surface of the transparent sheet 1, thereby smoothing the surface and eliminating light scattering, so that the colored surface 2 of the lower layer is displayed in the front.

In addition to acrylic resin, fluororesin, polycarbonate, and the like can be used as the material for the transparent sheet 1. Although liquid 3 can be water, it is better to use something like glycerin (refractive index 1.47), which is difficult to volatilize, has high viscosity, and has a high refractive index.Also, ethylene glycols are also suitable. ,
Oil etc. may also be used.

Approximately, the unevenness on the surface of the transparent sheet 1 is as follows:
It can be created by sandblasting, etc. It is also good to create by pressing a roughened roller or using photoresist.

To erase the displayed image, for example, the adhering liquid 3 may be absorbed and removed using an absorber 5 such as a sponge.If you want to repeatedly move the displayed image between the front and back without erasing it, The absorbent body 5 may be kept away from the rear. Other erasing methods are also possible, such as using a suction device or heating drying instead of the absorber 5.

Note that for miniaturization, it is preferable to provide the uneven surface inside the transparent sheet 1 and arrange the inkjet device inside.

In order to display a clear image, the surface of the transparent sheet 1 should be precisely formed as a conical concave surface, as shown in FIG. 2, so that the light from the colored surface 2 is totally reflected on the surface. In FIG. 2, this can be achieved by setting the angle θ to the optical critical angle θC of the transparent sheet 1 such that θ<90°−θC. If the refractive index of the transparent sheet 1 and the liquid 3 are the same, then if 90''-〇 is taken to be equal to the contact angle θ゛ between the transparent sheet 1 and the liquid 3, the surface of the liquid 3 will be flat. It is desirable to do so.

Alternatively, it may have a curved shape like a mortar shape. In that case, as shown in Figure 3 (a) and (b), the light from the colored part of the colored surface 2 is totally reflected so that the light from the colored part of the colored surface 2 does not go to the front when the display is not displayed. It is desirable that the region be ring-shaped.

As shown in FIG. 4, by dividing the colored surface 2 into R, G, and B pixels, red, i! , blue color display is possible. It is also good to make one pixel correspond to a plurality of concave portions.

As shown in FIG. 5, the size of the display pixel can be controlled by adjusting the amount of liquid 3 on one concave surface of the transparent sheet 1. It should be noted that if the convex portion is treated with water repellent treatment 8 using fluororesin, silicone resin, etc., water-repellent treatment 8 will prevent run-off and the like, thereby increasing the reliability of the display.

Also, in principle, it is possible to select a color depending on the amount of liquid 3 in one concave part, or to display multiple colored parts, but this would complicate the structure. It is difficult to create.

So far, we have explained the case where the pixels are circular, but the sixth
By processing as shown in the figure, a rectangular piece can be obtained. Of course, other forms are also possible.

A plurality of the concave portions may be arranged as glass elements, or a light-emitting display may be created by using the colored surface 2 as a filter and backlighting from the back.

Furthermore, although the refractive indexes of the liquid 3 and the transparent sheet do not have to be equal, it is preferable that the difference in their refractive indexes be within 0.3 because designing and manufacturing are easier if they are closer.

Then, in order to increase the display efficiency, the attached liquid 3
Since the surface of the transparent sheet 1 and the liquid 3 must be nearly flat or slightly convex, it is necessary to optimize the surface and interfacial tension between the transparent sheet 1 and the liquid 3 in advance and adjust the contact angle accordingly.

FIG. 7 shows a second embodiment of the invention.

That is, FIG. 7 shows a configuration in which the inkjet device 4 is arranged inside the loop of the transparent sheet 1 for miniaturization. The general operation of each part is the same as that shown in FIG.

The state of reflection of the light beam in the case of FIG. 7 is shown by dotted lines in FIG. That is, in the upper part of FIG. 8(a), the recesses of the transparent sheet 1 are filled with the liquid 3, and the display is made by light transmission from the rear surface, but when there is no liquid 3 in the lower part, the incident light is reflected. will not be displayed. As shown in this figure, if the surface is formed into isosceles prism-shaped grooves, external light will be reflected as is, making it possible to make the image contrast extremely high. This may be the type shown in Figure 8(b) in which the front and back of the transparent sheet 1 are reversed.
have the same effect. Furthermore, the configuration shown in FIG. 6 described above also has the effect of sharpening the edges of the displayed image. In this case, as shown in FIG. 9, resolution is better if the pixels are divided by a water repellent agent 7 or a partition.

As a simple embodiment of the present invention, when the surface of the transparent sheet 1 is made irregularly uneven by sandblasting or the like to diffusely reflect light and achieve light opacity, the transparent sheet 1 and If the refractive index of the liquid 3 is not equal or very close, the transparency when the liquid 3 is applied will be extremely poor, and the color of the colored surface 2 behind will become white and cloudy.
Moreover, the image appears blurry and the display efficiency decreases. Therefore, in this case, the difference in refractive index between the two is practically 0.
It is appropriate to set it to 1 or less. Furthermore, as mentioned above, if the surface is provided with regular irregularities of a special shape, the degree of diffused reflection will be reduced, so the difference can be made a little larger, but from a practical point of view, 0.3 is recommended. It is necessary to make sure that it is not exceeded.

In addition, for high-resolution display or R, G, and B color display, the higher the refractive index of the liquid 3 and the transparent sheet 1, the better the display will be when viewed from the side. Generally, the thinner the thickness d of the transparent sheet 1, the better. That is,
This is because the deviation X of the displayed area when viewed from the direction shown in FIG. 10 must be smaller than the size r of the colored surface 2. However, this is not the case when pixels are displayed using a plurality of concave portions.

[Effects of the Invention] As explained above, according to the present invention, since liquid adhesion is utilized on the recording member as an optical element whose surface is textured, it is very easy to form and erase images. ,
Furthermore, the configuration is simple and inexpensive. In addition, it has high resolution and is capable of large-sized displays, and
It can be colored and can easily be made to emit light.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and FIG.
FIG. 2(a) is a cross-sectional side view of the embodiment. (b) is an explanatory diagram when the concave part of the transparent sheet is made into a conical concave surface, Figures 3 (a) and (b) are explanatory diagrams when the concave part is made into a mortar shape, and Figure 4 is an explanatory diagram when the concave part is made into a concave shape. Explanatory diagrams, Figures 5 (a), (b), and (c) are explanatory diagrams when the display method has been improved, Figure 6 is another explanatory diagram of the shape of the uneven portion of the transparent sheet, and Figure 7 is a cross-sectional side view of the second embodiment, FIGS. 8(a) and 8(b) are explanatory diagrams of how the light beam is reflected in the device of FIG. 7, and FIG. 9 is an explanatory diagram of the shape of the uneven portion of the transparent sheet. Yet another explanatory diagram, FIG. 10, is an explanatory diagram of the relationship between the displacement of the displayed area and the size of the colored surface. 1... Transparent sheet 2... Colored surface

Claims (1)

[Scope of Claims] 1. A recording member as an optical element provided with an uneven treatment on one surface, and a member provided close to the other surface of the recording member and colored in either a single color or a plurality of colors. In addition, the image display device has a recording/writing section for depositing a liquid on one surface of the recording member, and the difference between the optical refractive index of the liquid and the optical refractive index of the recording member is small; Moreover,
Image display is performed by associating an appropriate number of the recording members as optical elements with one pixel and controlling on/off of total reflection of light inside the recording member depending on the presence or absence of liquid adhesion on one surface of the recording member. An image display device characterized in that: 2 The difference between the optical refractive index of the liquid and the optical refractive index of the recording member is 0.
The image display device according to claim 1, wherein the number is within 3. 3. The image display device according to claim 1, wherein the surface of the liquid attached to one surface of the recording member is flat or has a shape close to flat.