JPH0756547B2 - Transmissive display element - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transmissive light-receiving display element capable of displaying a bright screen.

(Prior Art) Currently, a CRT (Cathod Ray Tube, cathode ray tube) is mainly used as a display device for displaying a character graphic, a television image, and the like, but the CRT has a disadvantage of large volume,
Various thin display elements have been proposed as alternatives, and some have been put to practical use. These display elements can be classified into a light-emitting type and a light-receiving type. The light-emitting type includes a plasma display, a fluorescent display tube, an electroluminescence display, a light-emitting diode display, and the light-receiving type includes a liquid crystal display and an electro-luminescent display. There are chromic displays, electrophoretic displays, electro-optic crystal displays and the like. Although each of these thin display elements has advantages and disadvantages, in general, a light-emitting display element has a drawback in that a bright display can be obtained, but a driving voltage is high or power consumption is large. Although the display element generally consumes less power, it has a drawback that the display is difficult to see in a dark place because it is a light receiving type that does not emit light by itself.
For this reason, the light-receiving display element has been devised as a reflection type structure to take in a large amount of ambient light, but still the display is barely visible under weak ambient light. Therefore, in many cases, a light source for illumination is provided behind the light receiving display element. However, when the illumination light source is provided, the power consumption thereof is large, and the advantage that the power consumption of the light receiving display element is small is impaired. Therefore, in order to reduce the power consumption as much as possible and obtain a display brightness comparable to that of the light emitting display element, the incident light from the illumination light source should be used for the display as effectively as possible in the transmissive display element. Is essential. As a means for this, conventionally, for example, a fluorescent lamp is irradiated from an end surface of a transparent substrate of a liquid crystal display element, and incident light from the fluorescent lamp is repeatedly reflected inside the transparent substrate to effectively irradiate the entire display surface. It had a unique structure. (Proceedings of the 3rd Liquid Crystal Conference, page 24,
(1977) However, even with such a device, it is the current situation that a light-receiving display element still cannot obtain a display of sufficient brightness with low power consumption. For example, CR
In the active matrix type color filter built-in liquid crystal display element, which is attracting attention as a thin display element having a large display capacity capable of countering T and the possibility of color display,
A 1.5-inch color CRT that can obtain a brightness of 20 nits on the display screen even if a light source for illumination having a brightness of 400 nits at 4 W is obtained, and a brightness of 40 nits can be obtained at a power consumption of 4 W.
The screen brightness is inferior to that of. Therefore, the present inventor has arrived at the present invention by creating a light-receiving display element having a novel structure that can effectively use ambient light or incident light from an illumination light source for display.

(Object of the Invention) An object of the present invention is to provide a light-receiving display element capable of displaying a bright screen.

(Structure of the Invention) In the transmissive display element of the present invention, at least one transparent body is used as a support substrate for a display material, and the incident light from behind the support substrate is controlled by the display material to perform display. The transparent type display element is characterized in that a transparent resin layer is patterned on the back surface of the support substrate, and the patterned transparent resin layer is processed into a lens shape to form a minute lens array.

Examples The present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic view showing the structure of one support substrate used in one embodiment of the transmissive display element of the present invention. In FIG. 1, 1 is a 1.1 mm thick glass substrate, 2 is a TFT (Thin Film Transistor) formed of amorphous silicon, 3 is a Mo drain electrode, 4 is a Mo gate electrode, 5 is an indium oxide pixel electrode ( Transparent electrode).
Although not shown in the figure, the intersection of the drain electrode 3 and the gate electrode 4 is isolated by a silicon nitride insulating film. FIG. 2 is a schematic view showing the structure of an embodiment of the transmissive display element of the present invention formed by using the supporting substrate of FIG. 1, and a place corresponding to the position AA ′ of the supporting substrate of FIG. FIG. In FIG. 2, 1 is the glass substrate of FIG. 1, and 2, 3, 5 are TFs formed on the glass substrate 1, respectively.
T, a drain electrode, and a pixel electrode. 6 is a 1.1 mm thick glass substrate similar to 1, on which a dot-shaped color filter 8 formed at a position corresponding to the indium oxide common electrode 7 and the pixel electrode 5 formed on the entire surface is provided. Has been. The color filter 8 has three colors of red, blue and green.
The types are arranged alternately. The two glass substrates 1 and 6 have their peripheries bonded and fixed with an epoxy adhesive 9.
The gap is filled with a liquid crystal substance 10 containing a black dichroic dye, and constitutes a so-called guest-host type active matrix type color filter built-in liquid crystal display element. Further, a semi-cylindrical microlens array is formed on the back surface of the glass substrate 1. This was formed by the following method. First, a transparent phenolic photosensitive resin is applied to the back surface of the glass substrate 1 by a spinner to a thickness of 200 μm,
In addition to curing by the usual deep UV exposure method, it was heated above the glass transition temperature to smooth the resin surface and achieve a strong adhesive state with the glass substrate. Next, the same photosensitive resin was spinner-coated on this resin layer to a thickness of 20 μm, and patterned into stripes by the usual deep UV lithography technique. Further, the patterned transparent resin layer in this state was heated to a temperature not lower than the glass transition temperature to cause "drip" at the edge portion of the stripe shape and processed into a semi-cylindrical lens shape. In this embodiment, the liquid crystal substance is a display substance, and the transparent body as a supporting substrate of this display substance is two glass substrates. The liquid crystal material is the gate electrode 4,
The well-known guest-host type electro-optical effect is shown according to the voltage waveform selectively applied to the drain electrode 3 and the common electrode 7. That is, most of the incident light from the back of the glass substrate 1 is transmitted on the “on pixel”, and almost no incident light from the back of the glass substrate 1 is absorbed and transmitted on the “off pixel”. The transmitted light appears to be colored by the color filter formed corresponding to each pixel electrode, so that a color display by red, blue, green and a mixture thereof is eventually realized on a black background. Here, the effect of the minute lens array 11 will be described with reference to FIG. FIG. 3 is a diagram in which a part of the glass substrate 1 and the minute lens array 11 of FIG. 2 is drawn at a substantially accurate scale, and 12 is a state in which the liquid crystal substance transmits the incident light on the “on pixel”. , A so-called opening region. That is, as can be seen from FIG. 1, the incident light is controlled by the electro-optical effect of the guest-host type liquid crystal substance, the so-called pixel region is only the region of the pixel electrode 5 in FIG. 1, and the other regions are always incident. The light is blocked. In this embodiment, the first
The area occupied by the pixel electrodes in the figure is about 60% of the whole, and in FIG. 3, the length of the opening 12 is 180 μm and the interval between the openings is 70 μm. In FIG. 3, the glass substrate 1
Of the incident light from the back of, the light that takes the optical path of 20 goes straight through the opening 12 and effectively contributes to the display. In addition, the incident light taking the optical path of 21 or 22 is small lens array 11
It is refracted by and passes through the opening 12 and contributes effectively to the display. That is, in the transmissive display element of the present embodiment, all the incident light within the plane of FIG.
And effectively contribute to the display. However, in the conventional structure without the minute lens array 11, as shown by the broken line in FIG. 3, the incident lights 21 and 22 also go straight like 31 and 32 and reach the non-aperture portion and do not contribute to the display. . In this embodiment, a display brightness of 28 nits is obtained when an illumination light source having a brightness of 400 nits is installed behind the microlens array 11, which is more remarkable than the display brightness of 20 nits without the microlens array. There were many improvements, and a bright screen display was realized. Of course, even when no special illumination light source is installed, the transmissive display element of this embodiment can display a brighter screen than that of the conventional structure. Since a semicylindrical microlens array is used in this embodiment, a condensing effect on the aperture ratio in the direction parallel to the semicylindrical lens (the direction perpendicular to AA ′ in the plane of FIG. 1) is obtained. I wasn't able to
The effect is further improved by using a hemispherical micro lens array as the micro lens array, and the display brightness in the present embodiment is 28
It can be easily estimated that the knit will be improved to about 33 knits. In the above embodiments, the case of a liquid crystal display element having a so-called active matrix color filter built-in has been described, but the effect of the present invention is not limited to the color filter built-in method or the active matrix method, and a liquid crystal material The operation mode of is not limited to the guest host type. However, in the active matrix system in which a switching element is connected to each pixel to operate a display material such as a liquid crystal material, the switching element significantly reduces the aperture ratio of the display screen, and therefore the effect of the present invention is extremely remarkably exhibited. . Further, also in a liquid crystal display element having a structure in which a color filter array is installed at a position corresponding to each pixel, the color filter filters the incident light in terms of wavelength to significantly reduce the amount of transmitted light, that is, the brightness, so that the effect of the present invention is extremely remarkable. To be demonstrated.
Regarding the display substance, the liquid crystal substances described in the above examples do not limit the present invention at all, and for example, as a display substance, an electro-optical material represented by a known electrochromic substance or a substance known by the name of PLZT. It goes without saying that the present invention is also effective when a crystal or a magneto-optical crystal such as garnet is used. For example, when an electrochromic substance is used as the display substance, the number of supporting substrates may be one. Fig. 4 shows an example of this, 41 is a glass substrate, 42 is a TFT formed of polysilicon, 43 is a Mo drain electrode, 45 is a tin oxide pixel electrode, 50 is a tungsten oxide layer of a display material, and 52 is an ion conductive layer. Magnesium fluoride layer as, 47 is a tin oxide common electrode, 51 is a glass substrate 41
It is an acrylic light collector having a "kamaboko-shaped" microlens array provided behind.

As described above, according to the present invention, it is possible to obtain a light receiving display element capable of displaying a bright screen.

[Brief description of drawings]

FIG. 1 is a diagram showing the structure of one support substrate in one embodiment of the present invention, in which 1 is a glass substrate, 2 is a thin film transistor, 3 is a drain electrode, 4 is a gate electrode, and 5 is a pixel electrode. FIG. 2 is a sectional view showing the structure of an embodiment of the present invention using the supporting substrate of FIG. 1, 1, 2, 3, 5 are the same as in FIG. 1, 6 is a glass substrate, and 7 is The counter electrode, 8 is a color filter, 9 is an adhesive, 10 is a display material, and 11 is a microlens array. FIG. 3 is a diagram for explaining the effect of the embodiment of FIG. 2, where 1 and 11 are the same as in FIG. 2, 12 is the display aperture, 20, 21 and 22 are the optical paths of incident light, and 31 Reference numerals 32 denote the optical paths of incident light in the conventional structure without the microlens array 11 shown for comparison. FIG. 4 is a diagram showing another embodiment of the present invention.

Claims (1)

[Claims] 1. A transmissive display element of a system in which at least one transparent body is used as a support substrate for a display material, and incident light from the back of the support substrate is controlled by the display material to perform display. A transmissive display element, characterized in that a transparent resin layer is patterned on the back surface of a substrate, and the patterned transparent resin layer is processed into a lens shape to form a minute lens array.