JPH03291690A - Transmission scattering type optical device and transmission scattering type display device using the same - Google Patents

Abstract

PURPOSE:To obtain a bright display by disposing an optical member for controlling electrically a scattering state and a transmission state, totally-reflecting the light beam of a certain visual angle range in light beams from an observer side, and having a colored layer by which the totally-reflected light beam is absorbed. CONSTITUTION:In the part in which a transmission scattering optical material layer 1B of a transmission scattering type optical element 1 is in a transmission state, a light beam which is made incident from an observe 3A side travels straight in the transmission scattering type optical element 1, is subjected to total reflection by the inclined surface 4 of an optical member and reaches the absorbing surface 5 colored in black and is absorbed, and a light beam from a light source 8 is made incident from the inclined surface 4 side, and refracted at an angle determined by a relation of the optical member and refractive index of air of the back, and does not reach directly the observer 3A. Accordingly, in the part in which the transmission scattering optical material layer 1B of the transmission scattering type optical element 1 is in a scattering state, the light beam which is made incident from the observer side, and also, the light beam from the light source 8 of the back are scattered, the observer looks at its scattered light beam nearly irrespective of a position, and it looks like white. In such a way, a display of white and black is obtained, and a bright display is obtained in spite of a wide visual angle.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a transmission scattering optical device using a transmission scattering optical element whose light scattering characteristics change in response to an external input, and a transmission scattering optical device using the same. The present invention relates to a scattering display device.

[Prior Art] Liquid crystal display elements have been well known as display elements whose optical characteristics are changed by voltage. A liquid crystal optical element that has been put into practical use in particular is a twisted nematic (TN) type liquid crystal optical element that uses a pair of polarizing films.
It is used as a display element in various devices such as watches, calculators, word processors, and personal computers.

However, since these TN type liquid crystal optical elements use a polarizing film, they have the disadvantage that when trying to increase the contrast ratio, there is a large loss of light, resulting in a dark display. This was not so much of a problem in the case of reflective liquid crystal optical elements used outdoors, but in the case of transmissive liquid crystal optical elements that use a backlight, the amount of light from the backlight There was a problem that it would be dark unless it was made larger.

On the other hand, as a liquid crystal optical element that does not use a polarizing film, a dynamic scattering (DSM) type liquid crystal optical element is also known as a transmission scattering type liquid crystal optical element. Furthermore, recently, liquid crystal optical elements using a liquid crystal resin composite in which liquid crystal is dispersed and held in a cured material matrix have been attracting attention.

However, in these transmission scattering type liquid crystal optical elements, light does not travel straight when scattering, but is transmitted, and when transmitting, light travels straight and is transmitted. For this reason, if a reflective type is used, the background on the viewer's side is likely to be reflected in the transparent part, and if a transparent type is used, the background behind the viewer will be visible in the transparent part, reducing visibility. had.

It is desired to realize a bright, high-contrast display using such a transmission-scattering optical element.

For this reason, it has been proposed to arrange a black light absorption layer behind the transmission-scattering optical element, or to arrange a louver to allow highly directional light to enter from behind.

Furthermore, for example, Japanese Patent Application Laid-Open No. 62-121485 discloses a transmission-scattering optical element that achieves high contrast by arranging a cylindrical lens behind a transmission-scattering optical element and a light absorption means near its focal point. It is described that the device is obtained.

Furthermore, Japanese Patent Application Laid-open No. 50-81797 discloses that a prism for a light introduction body and a light source for illuminating the irradiation surface of the light introduction body are provided behind the transmission scattering optical element, the light is transmitted through the light introduction body, and a liquid crystal display is provided. It is described that by setting the incident angle of the irradiated light incident on the glass surface holding the glass surface to be larger than the critical angle, a liquid crystal display device that provides display with excellent quality can be obtained.

[Problems to be Solved by the Invention] In the transmission-scattering optical device disclosed in JP-A-62-121485, in order to increase the viewer's viewing angle, a lens is placed near the focal point on the side opposite to the viewer. The width of the provided light absorbing means must be increased, which reduces the amount of light incident from behind. For example, if the visual angle is set to ±10° vertically, or 20°, the loss is about 17%, but if the visual angle is ±30° vertically, or 60°, the loss is approximately 57%, which means that the loss of light from behind is extremely large. It had the problem of becoming.

On the other hand, when a louver is used, the light absorption surface of the louver may be located behind the observer's viewing angle range. In this case as well, there is a problem in that even if the illumination light is incident from an oblique direction, there is a large loss of illumination from behind due to the louver surface.

In the transmission-scattering optical device disclosed in JP-A-50-81797, a prism with a light-absorbing film is arranged so that the light from the rear light source is totally reflected on the front glass surface. The light from the light source is prevented from directly reaching the observer. Therefore, although the viewing angle is widened to almost the entire area, the amount of light irradiated from the light source behind is reduced, and the advantage of not using a polarizing film cannot be utilized, and it is difficult to obtain only a dark display. Furthermore, in this case, there are restrictions on the angle of incidence of the light incident on the liquid crystal element to the glass surface that holds the liquid crystal.
Requires highly directional illumination light. Therefore, there was also a problem that the light source optical system became complicated. In addition, when using external light with little directionality, a mask is used and only light at a specific angle of incidence is used, which causes a significant loss of light from behind and causes the display to become darker. had.

For this reason, there has been a demand for a transmission-scattering optical device that has less loss in the amount of illumination from behind and allows a wider viewing angle for the observer.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and provides a transmission scattering optical material layer of a transmission scattering optical element whose light scattering properties change in response to external input. Behind the surface, at least a portion of the light from behind can enter, a surface that totally reflects a certain range of light from the observer side, and at least a portion of the light totally reflected by that surface is absorbed. A transmission-scattering optical device characterized in that an optical member having an absorption surface having a colored layer is disposed, and the optical member having a total reflection surface and an absorption surface is a prism or an optical waveguide (light guide). A transmission-scattering optical device, and
A transmission-scattering optical device characterized in that the prism is triangular prism-shaped or cone-shaped, and a transmission-scattering optical device characterized in that the transmission-scattering optical element is a transmission-scattering liquid crystal optical element. , and a transmission-scattering display device characterized in that the transmission-scattering optical device is used in the display device.

The transmission-scattering optical device of the present invention uses a transmission-scattering optical element having a transmission-scattering optical material layer whose light-scattering properties change in response to external input. At least a part of the light from behind can enter behind this transmission-scattering optical material layer, and there is a surface that totally reflects light within a certain viewing angle range of the light from the observer side, and a surface that is totally reflected by that surface. An optical member having an absorption surface having a colored layer that absorbs at least a portion of light is arranged. As a result, a bright display can be obtained with less loss in the amount of illumination from behind, and a viewing angle for the viewer can be wide and a high contrast ratio can be obtained.

The transmission-scattering optical device disclosed in JP-A No. 50-81797 is equipped with a light-absorbing film so that the light from the rear light source is totally reflected on the front glass surface. A prism is placed. In such a transmission-scattering optical device, the incident light from the front side that passes straight through the transmission part of the transmission-scattering optical element does not reach the opening of the prism (the part without the light-absorbing film), and all of the light passes through the prism. directly reaches the light-absorbing film.

In contrast, the transmission-scattering optical device of the present invention is provided with a prism opening that totally reflects the incident light from the front side that has gone straight through the transmission portion of the transmission-scattering optical element. At least a portion of the light totally reflected by the surface is absorbed by the absorbing surface having the colored layer, and a portion of the light directly reaches the light absorbing surface to enable display. This allows the prism aperture to be significantly larger,
A brighter display is possible.

The transmission scattering optical element of the present invention whose light scattering properties change in response to external input changes the characteristics of the transmission scattering optical material layer in response to external input such as voltage, heat, magnetic field, etc. Known optical elements that are in a scattering state can be used. Specifically, a liquid crystal optical element using liquid crystal is preferable, and a DSM type liquid crystal optical element using dynamic scattering, a liquid crystal optical element using a liquid crystal resin composite in which liquid crystal is dispersed and held in a cured material matrix, etc. be. In particular, liquid crystal optical elements using the latter liquid crystal resin composite in the transmission scattering optical material layer have good scattering performance, do not require alignment treatment, are not in a liquid state, and are easy to manufacture, such as easy substrate gap control. Furthermore, it is easy to increase the size.

The optical member disposed behind the transmission-scattering optical material layer of this transmission-scattering optical element has a surface that totally reflects light in a certain visual angle range from behind, and at least a portion of the light that is totally reflected on that surface. and an absorbing surface having a colored layer on which is absorbed.

That is, a surface that totally reflects light within a certain viewing angle range among light incident from the observer side allows incident light from the opposite side to enter, although it is refracted.

As a result, when viewed from the observer side, light travels straight through the transmission portion of the transmission-scattering optical element, and at the total reflection surface of the optical member, the light travels at an angle within a specific incident angle range determined by the refractive index of the optical member. After the incident light is totally reflected, it enters the absorption surface or directly enters the absorption surface and is absorbed. On the other hand, light from behind is refracted by this surface and enters the optical member, regardless of the incident angle, and does not directly reach the viewer at that position. in this case,
If the absorbing surface is black, it will appear black to the observer.

Conversely, in the scattering part of a transmission-scattering optical element, the light incident from the observer side is scattered as is, and the light from the rear illumination is usually refracted by the total reflection surface of the optical member and enters obliquely. Similarly scattered. Of this scattered light, the light directed towards the viewer is perceived as white by the viewer.

This provides a black and white display. In this case, when using a liquid crystal optical element that controls transmission and scattering by applying a voltage, in order to obtain a black display on a white background, it is necessary to use a liquid crystal optical element that is in a scattering state when no voltage is applied. There is. For this purpose, a liquid crystal optical element using a liquid crystal resin composite in which the above-mentioned liquid crystal is dispersed and held in a cured material matrix is optimal.

In addition, if the color of the colored layer on the absorption surface is set to a color other than black, for example red, a display of white and red can be obtained. Furthermore, if you change the color of the lighting behind it to blue light, you can get a red and blue display.

[Effect] FIG. 1 is a side view showing the basic configuration of the present invention.

In FIG. 1, 1 is a transmission-scattering optical element, 1A is its front substrate, IB is its transmission-scattering optical material layer, LC is its back substrate, 2 is an optical member disposed behind the transmission-scattering optical element, 3A and 3B are observers, 4 is an inclined surface provided on the optical member that causes total reflection, 5 is an absorption surface having a colored layer 6, 7 is a surface in close contact with the rear substrate 1C, and 8 is a surface disposed behind. represents a light source. Note that 3A is the observer in the direction perpendicular to the front substrate surface of the transmission-scattering optical element;
B shows the viewer rotated θ clockwise upward from the vertical position.

In this figure, the optical member 2 having an inclined surface 4, an absorption surface 5, and a surface 71 is a prism having a right triangular prism cross section, and the inclined surface 4 is attached to the substrate surface of the rear substrate 1C of the transmission-scattering optical element. On the other hand, it is tilted counterclockwise at an angle of ψ1=45°, and the absorption surface 5 is tilted counterclockwise at an angle of ψ2=9 with respect to the substrate surface of the rear substrate IC of the transmission scattering optical element.
It is arranged at an angle of 0°, ie vertically, and is colored black.

In the portion where the transmission-scattering optical material layer IB of the transmission-scattering optical element 1 is in a transmitting state, the light incident from the observer 3A side travels straight through the transmission-scattering optical element and is totally reflected by the inclined surface 4 of the optical member. Then, it reaches the absorbing surface 5, which is colored black, and is absorbed.

On the other hand, light from the light source 7 at the rear enters from the inclined surface 4 side, but is refracted at an angle determined by the relationship between the optical member and the refractive index of the air at the rear, and does not directly reach the observer 3A. As a result, the transparent portion appears black to the observer 3A.

When the observer's position is changed clockwise by the above-mentioned angle θ, the light traveling straight comes to hit the lower part of the inclined surface 2, and finally comes to directly hit the absorption surface. Therefore, with a structure like this example, the viewing angle of the observer 3B will be approximately 90 degrees upward.

Conversely, when the observer's position is changed downward in a counterclockwise direction by the above-mentioned angle θ, the light traveling straight hits the inclined surface 4, and the critical angle of total reflection is determined by the optical member and the refractive index of the air behind it. When the light reaches a specific angle corresponding to , the light is not totally reflected on the inclined surface 4 and is emitted to the rear. On the other hand, in this case, the light from the light source 8 behind is also incident, so the light from the light source 8 behind is directly visible to the observer, making it difficult to see.

In the part where the transmission-scattering optical material layer 1B of the transmission-scattering optical element is in a scattering state, both the light incident from the viewer side and the light from the light source 8 behind are scattered, and the viewer can see the scattering almost regardless of the position. You will see light and it will appear white.

As a result, a white and black display is obtained, and the upper direction is approximately 90°.
You can see up to a certain angle determined by the optical member and the refractive index of the air behind it, specifically up to about 5 to 20 degrees.

This is because the viewing angle is wider than 90°, whereas the conventional example using a conventional cylindrical lens has a viewing angle of about 60°, and a bright display can be obtained despite the wide viewing angle.

In addition, in the conventional example in which a louver whose sloped surface is colored black instead of the prism shown in Fig. 1 is used, the upper part is almost 0.
degree and almost 90 degrees downward, but because the amount of light incident from behind is small, the brightness is darker than that of a prism. In addition, in order to widen the viewing angle,
You can make the louver longer, but it will become darker because the amount of light entering from the rear will decrease.

Note that this example shows only the basic configuration, and it is possible to change the color of the absorption surface to a color other than black, change the prism to a shape other than a right-angled isosceles triangle, divide it into multiple pieces, or change the shape from a triangular prism to a pyramid. It can also be shaped into a pyramidal shape such as a conical shape or a conical shape.

Further, the surfaces forming the prism may be curved surfaces. Further, it is preferable to form a low reflection layer on the inclined surface 4.

Specifically, there are the following examples.

The surface of the prism on the side of the transmission-scattering optical element can also be tilted without being in close contact with the transmission-scattering optical element. An example of this is shown in FIG. This angle is determined by the transmission scattering optical element 11.
The angle ψ is clockwise with respect to the board surface of the rear board 11C.
, is inclined. In the example of FIG. 1 described above, this angle ψ3 is 0°. In this case, a low reflection layer may be formed on the back side of the rear substrate 11G of the transmission scattering optical element 11 and on the surface 17 of the prism on the transmission scattering optical element side in order to reduce surface reflection. preferable. In this case, when the angle ψ3 of the surface 17 of the optical member 12 is increased, the downward viewing angle increases accordingly, and the depth becomes longer, but the viewing angle at which the black and white display can be seen widens.

Further, the angle ψ1 of the inclined surface in the example of FIG. 1 may be changed from 45°, and the angle ψ2 of the absorption surface may be changed from 90°.

5 Moreover, this prism can also be divided into a plurality of pieces and used. For example, if it is divided into 10 pieces, the depth will be l/10.
It can be made smaller. Furthermore, in this case, it is preferable to form a reflective surface on the outside of the absorbing surface, since the light from the rear light source can be used more effectively.

FIG. 3 is a side view showing another basic configuration of the present invention in which the prism is shaped like a pyramid, specifically a truncated pyramid.

In this case, a truncated pyramid-shaped prism 22 is arranged behind the transmission-scattering optical element 21, and the upper slope 24A and lower slope 24B, which are the slopes for total reflection, are the transmission-scattering optical element 21. are inclined counterclockwise at an angle ψ11 and clockwise at an angle ψ12 with respect to the back surface of the rear substrate. The opposite surface of this truncated pyramid is an absorption surface 25 on which a colored layer 26 is provided. and light source 28 behind
are placed. However, this truncated pyramid-shaped prism may be replaced with a truncated conical prism. The angles ψ1 and ψ12 differ depending on the viewing angle, but if the viewing angles are the same above and below, they should be the same angle, and normally designed so that the guided light is totally reflected once or more at the maximum viewing angle.

With this configuration, the amount of incident light from the opposite side increases compared to the case where a columnar prism is used, so a bright display is possible and the optical member can be made smaller.

In this case, the light transmitted from the transmission-scattering optical element 21 side is totally reflected by the inclined surfaces 24A, 24B and two other inclined surfaces (front side and back side) not shown in the figure, and is absorbed. It is absorbed by the colored layer on the surface and appears black. In this case, if the length of one side of the absorptive surface of the truncated pyramid is half the length of the bottom surface, the area of the colored layer that blocks light from the light source behind will be 0.5X O,5, and the brightness will be The reduction is only 25% compared to the case without the layer.

Note that a columnar prism with a trapezoidal cross section can also be used as a configuration similar to this.

In this case, the cross-sectional view is the same as that in FIG. 3, and the viewing angle in the left-right direction (front-back direction in the figure) becomes wider, but the area of the colored layer increases, so the display becomes darker. In the above-mentioned example in which the length of one side of the absorption surface is half the length of the bottom surface, the area of the colored layer that blocks light from the light source behind it occupies half the area.
The brightness is reduced by 50% compared to the case without the colored layer.

In addition, in the above explanation, all optical members were placed behind the back substrate of the transmission-scattering optical element, but by processing the back surface of the back substrate itself into a prism shape, it is not necessary to place the optical members separately. It's okay.

FIG. 4 is a side view showing another basic configuration of the present invention using a light guide as an optical waveguide as an optical member.

In this case, a light guide 32 is arranged behind the transmission-scattering optical element 31 and is bent and connected to an absorption surface 35 provided with a colored layer 36 .

This light guide 32 consists of a core portion with a high refractive index and a cladding with a low refractive index, and the interface thereof serves as a surface for total reflection. Specifically, there are light guide sheets and optical fiber arrays made of bundled optical fibers. Note that the cladding portion may be made of air.

Therefore, light incident on the incident side (transmissive scattering type optical element side) at an angle less than or equal to the critical angle is transmitted through repeated total reflection inside the light guide, and is absorbed by the colored layer.

Light from the light source 28 at the rear enters from the side of the light guide, is transmitted according to the refractive index, and reaches the back surface of the transmission-scattering optical element. However, since the angle of this arriving light is greater than the critical angle of the light guide, it is refracted at the interface of the light guide, passes across the light guide, and does not exit within the viewing angle range. It does not appear in the transparent part. On the other hand, in the scattering portion, even light incident from an angle is scattered, so light enters within the viewing angle and appears cloudy.

In this example, the light guide is placed perpendicular to the substrate surface of the overscattering optical element, and the viewing angles are the same up, down, left, and right.
By changing the angle of the light guide, the viewing angle can be changed vertically and horizontally.

Note that light guides tend to have narrower viewing angles and brighter displays than prisms.

The rear light source used in the present invention includes known illumination light sources such as tungsten lamps, halogen lamps, xenon lamps, cold cathode discharge tubes, hot cathode discharge tubes, LEDs, and EL.
It may also be one that guides and uses external light such as sunlight or indoor lighting. Furthermore, if necessary, a combination of reflecting mirrors such as a plane mirror, spherical mirror, ellipsoidal mirror, and parabolic mirror, a lens, and light guiding means such as an optical fiber may be used.

The transmission-scattering optical element of the transmission-scattering optical device of the present invention is
Any material can be used as long as its transmission and scattering can be artificially controlled by a transmission/scattering optical material layer. Among these, those using liquid crystal are preferred because they have low power consumption and high reliability. especially,
Optimal is one in which a liquid crystal cured material composite layer in which liquid crystal is dispersed and held in a cured material matrix is sandwiched between a pair of substrates with electrodes, and the scattering state and transmission state can be controlled by applying a voltage.

As the liquid crystal cured product composite layer of the transmission-scattering optical element sandwiching the liquid crystal cured product composite layer, any layer in which liquid crystal is dispersed and held in a cured product matrix can be used. Specifically, the liquid crystal may form independent bubbles and be encapsulated in microcapsules, these bubbles may communicate with each other, or the liquid crystal may form independent bubbles that are encapsulated in microcapsules. A portion may be filled with liquid crystal.

When such a liquid crystal cured product composite layer is sandwiched between a pair of substrates with electrodes and a voltage is applied between the electrodes, the refractive index of the liquid crystal changes depending on the voltage application state, and the cured product matrix changes. The relationship between the refractive index and the refractive index of the liquid crystal changes,
When their refractive indexes match, they are in a transmitting state (the incident light goes straight ahead), and when their refractive indexes are different, they are in a scattering state (the incident light does not go straight through, but is scattered).

Specifically, while a voltage is being applied, the refractive index of the cured material constituting the cured material matrix is made to match the ordinary refractive index (no) of the liquid crystal.

As a result, when the refractive index of the obtained cured product and the refractive index of the liquid crystal substance match, light is transmitted, and when they do not match, light is scattered (cloudy). Since the scattering properties of this element are higher than those of conventional DSM (dynamic scattering mode) transmission scattering optical elements, a high on-off ratio can be achieved.

This liquid crystal cured material composite layer is usually prepared by preparing a mixture of liquid crystal and raw materials for the cured material matrix, and then casting the mixture onto an electrode substrate and curing it, or by using a pair of electrode materials as in a normal liquid crystal cell. The periphery of the substrate may be sealed with a sealing material, and the mixture may be injected from the injection port and cured, so that the liquid crystal is dispersed and held in the cured material matrix.

Examples of the cured matrix include resin matrices and ceramic matrices, but it is preferable to use a resin matrix because it is easy to manufacture and the refractive index can be easily adjusted.

Among these, productivity is improved by using a photocurable resin or thermosetting resin that can be cured in a closed system as a raw material for the resin matrix, and photocuring or thermosetting using a solution of this resin dissolved in liquid crystal. , both the casting and injection manufacturing methods described above are applicable. In particular, it is preferable to use a photocurable resin and photocure.

By making the refractive index of the cured material matrix match the refractive index of the liquid crystal (00), when no voltage is applied, the scattering state will be caused by the difference in refractive index between the unaligned liquid crystal and the cured material matrix. (that is, a cloudy state), and since the incident light does not travel straight, it is hardly focused on the input end of the optical fiber for output light transmission, and almost no output light is generated.

During the curing process, this element is cured by applying a sufficiently high voltage only to specific parts, or by being heated to a temperature higher than the phase transition point of the liquid crystal. It is also possible to always make it transparent. In addition, any intermediate voltage can be cured by applying an intermediate voltage, or by de-curing with a sufficiently high voltage applied and then completing curing without applying a voltage. It is also possible to obtain an indication of the degree of scattering (the scattering degree at the time of scattering is arbitrary). This makes it possible to partially display fixed frames, characters, etc., or to display photographic images.

It is preferable to use a transmission-scattering liquid crystal optical element in which the refractive index of this cured material matrix matches the refractive index (no) of the liquid crystal used, and to make them completely match, but this may have an adverse effect on the transmission state. It can be used as long as it matches closely to the extent that it does not give . Specifically, when using a resin matrix, it is preferable to keep the difference in refractive index to about 0.15 or less. This is because the resin matrix swells with the liquid crystal, and the refractive index becomes closer to that of the liquid crystal than the original refractive index of the resin matrix itself, so even if there is a difference of this degree, almost all light will pass through. It's for 4 reasons.

In order to use this transmission-scattering optical element for display, it is sufficient to pattern the electrodes in a desired pattern, but it is also possible to arrange an active element such as TPT in each pixel so that various displays can be displayed by a collection of dots. It's okay.

These electrodes are usually transparent electrodes on both substrates, but opaque electrodes made of metal or the like may be provided on a part thereof for the purpose of low resistance leads or the like. In this case, when a portion other than the active pixel is in a scattering state, it is preferable to form a light-shielding film on a corresponding portion of the front substrate of the transmission-scattering optical element.

In the present invention, the color may be adjusted by laminating a protective plate such as a glass plate or a plastic plate or laminating a color filter on the front side or the back side of the transmission scattering optical element.
A color filter or a color light source may be used to make each display pattern multicolored.

The raw materials for the cured material matrix, especially the resin matrix, constituting the above-mentioned liquid crystal cured material composite layer include monomers and oligomers of various resins, polymers that are dissolved in solvents, etc., and are mixed with liquid crystal to form a mixture. used. In this case, it is preferable to use a material in which the raw material of the cured material matrix is dissolved in liquid crystal to form a homogeneous solution, but a material in the form of latex may also be used.

When supplying a mixture onto a substrate by casting, it is also possible to use a method that distills off the solvent or generates by-products such as gas during curing, but when injecting liquid crystal into a cell and post-curing it, , use a mixture that can be cured in a closed system without the need for distillation of the solvent and without generating by-products such as gas during curing.

Therefore, as mentioned above, it is preferable to use a photocurable resin from the viewpoint of productivity, and it is particularly preferable to use a photocurable vinyl resin.

Specifically, photocurable acrylic resins are exemplified, and those containing acrylic oligomers that are polymerized and cured by light irradiation are particularly preferred.

The liquid crystals used in these cases include nematic liquid crystals and smectic liquid crystals, and they may be used alone or as a composition, but in order to meet various required performances such as operating temperature range and operating voltage, it is necessary to use a composition. It would be more advantageous to have one. especially,
Preference is given to using nematic liquid crystals.

In addition, when a photocurable resin is used for the liquid crystal used in the liquid crystal cured product composite layer, it is preferable that the photocurable resin is dissolved uniformly, and the cured product after light exposure is not dissolved or When using a composition that is difficult to dissolve,
It is desirable that the solubility of each liquid crystal be as close as possible.

When manufacturing the liquid crystal cured product composite layer, the raw material for the cured product matrix and the liquid crystal may be mixed to form a mixture such that the ratio of the cured product matrix to the liquid crystal is about 5:95 to 75:25. It may be used as a viscous substance rather than a liquid one.

When manufacturing a liquid crystal cured product composite layer, it is possible to form a cell and inject it from an injection port like a conventional ordinary liquid crystal display element, but it is also possible to form a cell and inject it from an injection port like a conventional ordinary liquid crystal display element. By supplying the mixture and superposing the opposing substrates, a transmission-scattering optical element can be manufactured with extremely high productivity.

The gap between the substrates can be operated at 5 to 100 μm, but if the applied voltage and contrast during on/off are taken into consideration, in the case of a liquid crystal cured material composite layer, the gap is 7 to 40 μm.
It is appropriate to set it to μm.

This transmission-scattering type liquid crystal optical element may include a dichroic dye, a simple dye, or a pigment added to the liquid crystal, or may use a colored cured material matrix.

By using a plastic substrate as the substrate with electrodes, a long transmission-scattering optical element using a continuous plastic film can be easily manufactured.

Furthermore, since the transmission-scattering optical element of the present invention is generally about the same size as a normal liquid crystal display element, cells are formed using a glass substrate in the same way as a normal liquid crystal display element, and then the cells are injected. Even if it is 8, there is almost no decrease in productivity.

By creating a transmission-scattering type liquid crystal optical element using a liquid crystal cured material composite layer in this way, there is a low risk of shorting between the upper and lower transparent electrodes, and it is possible to reduce the risk of short-circuiting between the upper and lower transparent electrodes. There is no need to strictly control the gap between the substrates, and a transmission-scattering liquid crystal optical element that can control the transmission state and scattering state can be manufactured with extremely high productivity.

When applying a voltage for driving this transmission-scattering type liquid crystal optical element, it is sufficient to apply an alternating current voltage that changes the alignment of the liquid crystal. Specifically, 10~ at 5~100v
An AC voltage of about 1000H2 may be applied.

Furthermore, a lens, prism, filter, etc. may be arranged on the observer side of this transmission-scattering optical element to change the viewing angle or change the color. Specifically, the portion of the rear prism surface 16 in FIG. 2 that is inclined at an angle ψ8 may be separately placed on the viewer's side of the transmission-scattering optical element.

[Example〕 Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 An empty cell was prepared by using two glass substrates provided with electrodes made of ITO patterned to enable display of Japanese characters, and sealing the periphery with a sealing material with a 20 μm spacer interposed.

7 parts of 2-ethylhexyl acrylate and 15 parts of 2-hydroxyethyl acrylate, acrylic oligomer (
24 parts of rM-12004 (manufactured by Toagosei Kagaku Co., Ltd.), 0.9 parts of Grocure 1116J manufactured by Merck Co., Ltd. as a photocuring initiator, and 64 parts of rE-8J manufactured by BDH Corporation as a liquid crystal were uniformly dissolved. , produced a liquid crystal mixture.

This liquid crystal mixture was injected into the empty cell described above and exposed to ultraviolet rays for 30 seconds to produce a transmission scattering type liquid crystal optical element. In this transmission-scattering liquid crystal optical element, the refractive index of the hardened resin that makes up the resin matrix is
Since the refractive index of the liquid crystal is approximately equal to the ordinary refractive index (no) of the liquid crystal, the refractive index of the two is different when no voltage is applied, and the whole becomes a scattering (cloudy) state, and an alternating current voltage (no) is applied between the desired electrodes. When AC 35 V, 50 Hz) was applied, only that part became transparent.

A triangular prism-shaped lead glass prism with a cross section of ψ = 45° and ψ2 = 90° in the form of a right isosceles triangle (refractive index = 1.80
) The lower surface of the absorbing surface 5 of the prism is painted black with almost the same refractive index as the prism, and the inclined surface 4 is coated with MgF2 as an anti-reflection film.
The film was shaped, placed so that the surface 7 perpendicular to the absorption surface 5 was in close contact with the rear substrate 11G of the transmission-scattering liquid crystal optical element, and bonded with an optical adhesive. A light source 9 was placed behind the prism.

This transmission-scattering optical device uses an AC voltage (
When AC35V, 50)1z) is applied, only that part appears black on a white background. This viewing angle is approximately 9
0', the downward angle is 20°, and the contrast ratio is approximately 15
Met.

In addition, the brightness in the scattering state is the same as that of the prism. It was f37o% compared to the case where it was not.

Furthermore, when the color of the colored layer was blue, the transparent portion appeared blue, and when the colored layer was made red, the transparent portion appeared red. In this case, the background color also tended to change from white to slightly blue or reddish.

Furthermore, if the color of the colored layer was kept black and the color of the light source was changed to blue, the transparent part appeared black against the blue-white background. By making the light source convertible between blue and red, and changing the color depending on the displayed content, the transparent parts appeared black against a blue-white background or a red-white background.

In addition, by applying a voltage or applying a magnetic field to the area other than the Japanese character display area and curing it so that it becomes a normally transparent state, only the Japanese character display area can undergo a transmission-scattering change. Therefore, the display can be reversed to the above, that is, the display can be white on a black background.

Example 2 Instead of the prism of Example 1, a prism made of borosilicate glass (refractive index = 1.50) was used.

The contrast ratio and the upper viewing angle were almost the same as in Example 1, but the lower viewing angle was 5'', which was a rather narrow viewing angle, and the brightness in the scattering state was also slightly reduced to about 65%.

When a prism with ψ=30° was used instead of the prism with ψ1=45°, the brightness was brighter than in Example 2, but the viewing angle was reduced to 72° vertically.

Conversely, when using a prism with ψ1 = 60°,
Although it was darker than Example 2, the viewing angle was expanded, and it was
It became 18°.

Comparative Example 1 When a louver inclined at 45'' was used in place of the prism of Example 2, the contrast ratio and upper viewing angle were almost the same as in Example 2, but the lower viewing angle was 0°. , the viewing angle was narrow.

In addition, the brightness in the scattering state is also about 20% higher than that in Example 2.
% decreased and was dark.

Example 3 Instead of the prism of Example 2, a prism as shown in FIG. A low reflection layer formed by a film) was placed.

The upper viewing angle was almost the same as in Example 2, but the lower viewing angle was wider at 13°, and the contrast ratio and brightness were almost the same as in Example 1.

Example 4 Instead of the prism of Example 2, as shown in FIG.
Prisms 42A and 42B having a right triangular cross section with ψ = 35° and ψ2 = 90° are placed behind the prisms so that the absorption surfaces 45A, 45B and the colored layers 46A, 46B on the lower surface thereof are continuous. They were stacked and placed behind the transmission scattering optical element 41.

The viewing angle was approximately 90° upward and 10° downward, the contrast ratio was approximately 10, and the brightness was approximately 70%.

Example 5 Instead of the prism of Example 1, an acrylic prism array 52 as shown in FIG. 6(A) was placed behind the transmission scattering optical element 51.

This prism array 52 had an angle of ψ1 of 45° and an angle of ψ2 of 90°, as shown in a partially enlarged view in FIG. 4(B).

In this case, a colored layer 56A is provided on the lower surface side of the absorption surface 55.
Two types were created: one in which only the aluminum reflective layer 56B was provided, and the other in which an aluminum reflective layer 56B was further provided.

The viewing angle is approximately 90° upwards and 5° downwardly, the contrast ratio is approximately 10, and the brightness of the one with the aluminum reflective layer 56B overlapping is better than the one with only the colored layer 56A without it. The ratio was improved and became brighter, and it was about 60% in the case where a reflective layer was provided. Furthermore, in this example, the depth could be significantly reduced compared to the case where one prism was used.

Note that by arranging this prism array upside down, the viewing angle was also reversed up and down.

Similar effects were also obtained when the aluminum reflective layer on the absorption surface of the prism was replaced with a scattering reflective layer made of a white coating.

Example 6 Instead of the prism array of Example 5, an acrylic prism array 62 as shown in FIG. 7(A) was arranged behind the transmission scattering optical element 61.

This prism array 62, as shown in FIG. 7(B),
Contrary to the examples shown in FIGS. 1, 2, 5, and 6, the absorption surface 65 is arranged on the upper side, ψ1=45° (clockwise since it is reversed), ψ4=10° , L, + La ten L
When x is 100, L+=12, L2=28, t
, 5=eo. Furthermore, a black colored layer 66A and an aluminum reflective layer [16B] were formed on the absorption surface.

The viewing angle was 10° above and 90' below, the contrast ratio was about 15, and the brightness was about 60%.

As a light source behind this, an EL and a cylindrical lens (arranged so that the light emitting point of the EL is at the focal point) were placed and illuminated with parallel light in the horizontal direction, and the contrast ratio improved to approximately 20. 6 The brightness has also improved.

Example 7 Instead of the prism array of Example 5, an acrylic prism array 72 as shown in FIG. 8 was placed behind the transmission scattering optical element 71.

This prism array 72 has ψ, =30'', ψ2=
A light source 78 and a mirror 79 were combined so that the light from the light source was incident from above at an angle of approximately 45°.

The viewing angle was from 18° downward to 90°, the contrast ratio was about 30, and the brightness was about 110%. For this reason, this device had a rather narrow viewing angle, but within that range it was possible to display brighter images than without the prism.

Therefore, it is suitable for public displays where the field of view is fixed, such as only looking up from below.

Example 8 Instead of the prism array of Example 5, an array of acrylic truncated pyramidal prisms as shown in FIG. 3 was placed behind the transmission scattering optical element 21. The angle ψ and ψ1□ of this prism were both 80° (same in the left and right directions). The length of one side of the colored layer 26 of the absorption surface 25 was 48% of the length of the bottom surface.

As a result, the contrast ratio is approximately 20, and the viewing angle is 6 for each top and bottom.
0°, 60° on each side, and the brightness of the scattered state is about 7
It was 5%.

When a columnar prism with the same trapezoidal cross section was used instead of the acrylic truncated pyramidal prism, the viewing angle was about 90° on the left and right sides, and the brightness in the scattering state was about half.

Example 9 Instead of the prism of Example 1, a plurality of light guide sheets each having a core material made of acrylic resin (refractive index: 1.50) were stacked and used as shown in FIG. 4. The thickness of the light guide sheet is 1 mm, and the refractive index is 1 between each sheet.
．． 39 oil was inserted to reduce Fresnel reflections that occur on the sides of the light guide sheet.

As a result, the contrast ratio is approximately 10, and the viewing angle is 70% for the upper piece.
Met.

Furthermore, when a plastic optical fiber was used as a light guide, the same contrast ratio and vertical viewing angle as in the case were obtained, but the horizontal viewing angle was narrower at about 68°.

Example 10 Instead of a transmission-scattering type liquid crystal optical element provided with electrodes made of ITO patterned without using a diagonal table, each pixel was provided with TP.
Examples 1 to 9 were conducted using a matrix-shaped transmission scattering type liquid crystal optical element formed with T (thin film transistor).
This is a transmission scattering type liquid crystal optical device.

This transmission-scattering type liquid crystal optical device could display any image rather than a numerical display using Japanese characters, and could also be used as a liquid crystal television.

FIG. 9 shows a specific example of this, in which a prism array 82 is placed behind a transmission-scattering optical element 81, fitted into a case, and a planar light source 88 is placed on the back side. By making the light source 889 openable and closable, when using external light, the power consumption by the light source can be reduced by rotating or removing the light source 88 and letting the external light in from the right side.

[Effects of the Invention] As described above, according to the present invention, the transmission scattering optical element electrically controls the scattering state and the transmission state, and the total reflection of light within a certain viewing angle range from the viewer side. By arranging an optical member that has a surface that reflects light and an absorption surface that has a colored layer that absorbs at least a portion of the light that is totally reflected on that surface, the loss of light amount of illumination from behind can be reduced and a bright display can be achieved. At the same time, it is possible to obtain a wide viewing angle for the observer and a high contrast ratio.

The light source can be a normal backlight or external light. Furthermore, by supplying highly directional light using a reflector, lens, etc., even brighter display becomes possible.

In particular, by using a prism array, the depth can be reduced, the size can be reduced, and a bright display with a white background can be easily obtained. It can be used for various purposes such as , television, etc.

In addition, a transmission-scattering type liquid crystal optical element using a liquid crystal resin composite in which liquid crystal is dispersed and held in a cured material matrix controls transmission and scattering by controlling the refractive index, so that incident light is not absorbed. Compared to conventional TN-type liquid crystal display elements, it is usually more than twice as bright (and even when a high amount of light is incident, there is almost no temperature rise in the transmission-scattering type optical element, and it is highly reliable.

In addition to this, the present invention can be applied in various other ways as long as the effects of the present invention are not impaired.

[Brief explanation of the drawing]

FIG. 1 is a side view showing the basic configuration of the transmission-scattering optical device of the present invention. 2 to 9 are side views of other examples of the transmission-scattering optical device of the present invention. Transmission scattering optical element = 1.11.21.31°51.
61.71.81 Optical member: 2.12 Observer: 3A, 3B Slanted surface = 4.14.24A, 24B Absorption surface = 5
．． 15.25.35.45A, 45B, 5 colored layer = 6.16.26.36.46A, 46B,
66A, surface = 7.17 Light source: 8.18.28.38.78.88 Prism = 22.52A, 52B Light guide: 32 Prism array: 52.62.72.82 Reflective layer: 5
6B, 66B Mirror Near 9 56A, 3 4th Figure 35 Two absorption surfaces 36: Blue layer diagram (A) (B)

Claims (7)

[Claims] (1) At least a portion of the light from behind can enter behind the transmission scattering optical material layer of the transmission scattering optical element whose light scattering characteristics change in response to external input, and the light from the observer side A transmission scattering device characterized by arranging an optical member having a surface that totally reflects light within a certain range, and an absorption surface that has a colored layer that absorbs at least a portion of the light totally reflected by the surface. type optical device. (2) A transmission-scattering optical device characterized in that the optical member having a total reflection surface and an absorption surface according to claim 1 is a prism. (3) A liquid crystal optical device characterized in that the prism according to claim 2 has a triangular prism shape. (4) A transmission scattering optical device, wherein the prism according to claim 2 is cone-shaped. (5) A transmission-scattering optical device, wherein the optical member having a total reflection surface and an absorption surface according to claim 1 is an optical waveguide. (6) The transmission-scattering optical device according to any one of claims 1 to 5, wherein the transmission-scattering optical element is a transmission-scattering liquid crystal optical element. (7) A transmission-scattering display device, characterized in that the transmission-scattering optical device according to any one of claims 1 to 6 is used as a display device.