JPH05333330A - Transmissive scattering optical device and transmissive scattering display device using the same - Google Patents

Abstract

PURPOSE:To set a visual angle in a front face direction and to enable bright display by providing a prism in a specified shape at the back of a transmissive scattering optical element and forming an absorbing plane at the apex part of the prism. CONSTITUTION:A bottom face 7 of a prism 2 is arranged in close contact to a transmissive scattering optical element 1, the angle ... formed by the side face 4 and the bottom face 7 of the triangular prism 2 having a triangular cross section is set to satisfy 65 deg.<=...<=90 deg., and an absorbing plane 5 is formed at the apex part of the prism 2. Namely, light straightly advancing through the transmitting part of the transmissive scattering optical element 1 is made incident on the bottom face 7 of the prism 2 and is reflected on the side face of the prism 2 or directly arrives at the absorbing plane 5 on the side face at the apex part, and only one part of the light is reflected and returned to the side of an observer 3. Therefore, that part is observed in black. Since the light is made incident on the part not equipped with the absorbing plane 5 on the side face 4 of the prism 2, the light of illumination 8 can be utilized as well, and bright display is enabled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive-scattering optical device using a transmissive-scattering optical element whose light-scattering characteristics change in response to an external input, and a transmissive-scattering display device using the same. is there.

[0002]

2. Description of the Related Art Liquid crystal display elements have been well known as display elements whose optical characteristics are changed by voltage. In particular, as a liquid crystal optical element that is remarkably put into practical use, there is a twisted nematic (TN) type liquid crystal optical element using a pair of polarizing films, which is used as various display elements such as a clock, a calculator, a word processor, and a personal computer.

However, these TN type liquid crystal optical elements are
Since the polarizing film is used, there is a drawback in that the loss of light is large when trying to increase the contrast ratio and the display becomes dark. This is not a problem in the case of a reflective liquid crystal optical element used outdoors, but in the case of a transmissive liquid crystal optical element using a backlight, the light intensity of the backlight is large. There was a problem that it would be dark unless the value was increased.

On the other hand, as a liquid crystal optical element which does not use a polarizing film, a dynamic scattering (DS) is used as a transmission scattering type liquid crystal optical element.
M) type liquid crystal optical elements have been conventionally known. Further, recently, attention has been paid to a liquid crystal optical element using a liquid crystal resin composite in which liquid crystal is dispersed and held in a cured product matrix.

However, in these transmission / scattering type liquid crystal optical elements, light does not go straight when scattered, but it passes through, and when it passes, light goes straight forward and goes through. Therefore, if it is used in the reflective type, the background on the viewer side is easily reflected in the transmissive part, and if used in the transmissive type, the background behind is visible in the transmissive part, which reduces the visibility. I had.

Using such a transmission / scattering type optical element,
It is desired to realize a bright and high-contrast display. For this reason, it has been proposed to dispose a black absorption surface behind the transmission / scattering type optical element or dispose a louver for allowing light having a strong directivity to enter from behind.

Further, for example, in Japanese Unexamined Patent Publication (Kokai) No. 62-121485, a cylindrical lens is provided behind a transmission / scattering type optical element,
It is described that a high-contrast transmission / scattering optical device is obtained by disposing a light absorbing means near the focal point. Furthermore, JP-A-50-81797 and U.S. Pat.
No. 62 describes arranging a prism having an absorption surface behind a transmission / scattering type optical element.

[0008]

The transmission / scattering type optical device disclosed in Japanese Unexamined Patent Publication No. 62-121485 has a lens near the focal point on the side opposite to the observer in order to increase the viewing angle of the observer. Since the width of the provided light absorbing means must be increased, the amount of light incident from the back is reduced. For example, when the viewing angle is ± 30 ° up and down, that is, 60 °, it is about 57% or more, the problem that the light amount loss of the illumination from the back becomes large, the problem that a precise lens design is required, the light absorption means individually. However, there is a problem in that it must be accurately arranged near the focal point of the lens.

On the other hand, when the louver is used, the light absorbing surface of the louver may be located behind the viewing angle range of the observer. In this case, the viewing angle cannot be set to the front. That is, there was a problem that the direction had to be inclined in either direction from the front.

In the transmission / scattering type optical device disclosed in Japanese Patent Application Laid-Open No. 50-81797, a prism with a light absorbing film is arranged so that the light from the back illumination is totally reflected by the front glass surface. This ensures that the light from the illumination behind does not reach the observer directly. Therefore, although the viewing angle becomes wide, it is difficult to obtain only a dark display.

Further, in the transmission / scattering type optical device of US Pat. No. 4,726,662, it is shown that a prism having a triangular prism shape or a conical prism, one surface of which is an absorption surface, is arranged.

3 and 4 show side views of those examples. In FIG. 3, reference numeral 21 denotes a transmission / scattering type optical element, 22
Is a triangular prism with a right-angled triangular cross section, 24 is a side surface,
Reference numeral 25 denotes another side surface which is an absorption surface for absorbing light. In FIG. 4, 31 is a transmission / scattering type optical element, 32 is a quadrangular pyramid prism with a right apex angle, 34 is a side surface, and 35 is another. Shows an absorption surface which is a side surface of the light absorption surface and absorbs light.

When the triangular prism as shown in FIG. 3 is used, the eyesight of the observer is almost 90 ° downward, and when the prism is turned upside down, it is 90 ° upward. For this reason, it cannot be used for things viewed from the front. Further, in such a prism, strictly forming a colored layer only on the entire surface of the absorption surface 25, or strictly forming a reflective layer only on the entire surface of the side surface 24 means that those layers are formed even on the adjacent surfaces. It adheres easily, and it is difficult to form it strictly, and the productivity is poor.

Further, when Ψ is 45 °, the average value of the allowable angle of incidence of light is about 54 °, and when an illuminator that emits omnidirectional light is used, the maximum transmittance is only 30% or less. .. Further, by forming a reflecting surface on the absorbing surface, it is possible to reflect the light incident on the absorbing surface from the outside of the prism and reuse it, but this efficiency is not so large.

Further, when the quadrangular pyramid prism as shown in FIG. 4 is used, the viewing angle is substantially 90 ° on the lower side.
However, in this case, the light does not become invisible immediately when viewed from above the horizontal, but the light enters the black portion, so that it gradually becomes gray, and finally it cannot be distinguished from the background. For this reason, it is not suitable for applications that require a viewing angle in the front direction.

Therefore, there has been a demand for a transmission-scattering type optical device which has a viewing angle in the front direction, enables bright display, and is easy to manufacture.

[0017]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a transmission / scattering optical material layer of a transmission / scattering type optical element whose light scattering characteristic changes in response to an external input. In a transmission / scattering type optical device in which a prism is placed behind the lens so that its bottom surface is in close contact with the back surface of the transmission / scattering type optical element, the prism has a triangular cross section or a part near the top of the triangular shape with a notch. A prism having a curved shape, the angles Ψ ₁ and Ψ ₂ formed by the two side surfaces of the prism with respect to the bottom surface are 65 ° ≦ Ψ ₁ ≦ 90 ° and 65 ° ≦ Ψ ₂
≦ 90 °, and at least _one of Ψ ₁ and Ψ ₂ is 90 °
Provided is a transmission / scattering type optical device characterized by having an absorption surface in the vicinity of the top of the prism.

Further, the prism having a triangular cross section is a prism having a triangular prism shape, and 65 ° ≦ Ψ ₁ ≦ 87 ° and 65 ° ≦
Ψ ₂ ≦ 87 °, or a prism whose cross section is triangular is a cone-shaped prism, and the side surface and the bottom surface on a surface orthogonal to the side surface of the cone-shaped prism and perpendicular to the bottom surface. Provided is a transmission-scattering type optical device characterized in that all angles ψ formed by and are set to 65 ° ≦ Ψ ≦ 87 °.

Further, the prisms having a triangular cross section are polygonal prisms cut out near the apex thereof, and the notched surfaces near the apex are absorption surfaces. A transmission / scattering type optical device,
When the height from the bottom surface to the top of the prism whose cross section is triangular is H ₀ and the heights from the bottom surface to the lower end of the absorption surface are H ₁ and H ₂ , respectively, 0.30 ≦ H ₁ / H ₀ ≤ 0.70 and 0.30 ≤
H ₂ / H ₀ ≦ 0.70, transmission-scattering type optical device, and transmission-scattering type optical device characterized by arranging illumination behind those prisms, and their transmission-scattering type Provided is a transmission / scattering type display device characterized by using an optical device for a 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 characteristics change in response to an external input. Behind this transmission / scattering optical material layer, its bottom surface is arranged substantially parallel to the transmission / scattering optical material layer, and its top is so that the angle Ψ formed by the side surface and the bottom surface of the prism is 65 ° ≦ Ψ ≦ 90 °. Prisms having triangular cross-sections with adjacent side surfaces as absorbing surfaces are arranged in series. Or, a polygonal prism having a shape cut out near its top, and more preferably a prism having a trapezoidal cross section cut along a plane substantially parallel to the bottom surface thereof so that the cross section becomes trapezoidal. The prisms having the absorption surface are connected and arranged.

As a result, the viewing angle can be obtained substantially symmetrically from the front, the light amount loss of the illumination from the back is small, a bright display can be obtained, and a high contrast ratio can be obtained.

In the transmission / scattering type optical device shown in the above-mentioned US Pat. No. 4,726,662, as described above, a prism having a triangular shape or a prism having a cone shape, one surface of which is an absorbing surface, is used. Since it is placed behind, the viewing angle is not the front but the direction inclined from the front in any direction.

On the other hand, in the transmission / scattering type optical device of the present invention, the angle Ψ formed by the side surface and the bottom surface of the prism having a triangular cross section is set to 65 ° ≦ Ψ ≦ 90 °. An absorption surface is formed near the top. For this reason, the light traveling straight through the transmission part of the transmission / scattering type optical element is incident on the prism having a triangular cross-section from its bottom surface and is reflected by the side surface of the prism or directly on the absorption surface or the top surface of the side surface near the top. In this case, it reaches the absorption surface on the upper surface, and only a part of it reaches the observer side by being reflected, so that part looks black. As the prism having a triangular cross section, specifically, a prism having a triangular cross section or a conical prism can be used.

By forming the absorption surface near the top of the prism having a triangular cross section, the viewing angle can be made to be the front direction as compared with the case where one side surface is entirely used as the absorption surface.

Since the light enters the prism from the side surface of the prism where the light-shielding surface such as the absorption surface and the reflection surface is not provided, the light for the illumination in the rear can be sufficiently used, which is relatively high. Bright display is possible.

According to the present invention, a reflection type display system utilizing illumination from the observer side is provided by providing a reflection surface for reflecting light to the inside of the prism on the side surface of the prism which is not provided with an absorption surface. Can also be used. Also in this case, of the light incident from the observer side, the light scattered on the prism side can be partially reused, and a relatively bright display can be performed.

FIG. 1 is a sectional view of a transmission / scattering type optical device using a prism having a triangular cross section according to the present invention.
In FIG. 1 and FIG. 2 described later, two prisms are shown above and below for the sake of clarity, but in reality, a plurality of prisms are connected in the vertical and depth directions of the drawing.

In FIG. 1, 1 is a transmission / scattering type optical element,
2 is a prism with a triangular cross section placed behind the transmission / scattering optical element, 3 is an observer, 4A and 4B are side surfaces of the prism, 5A and 5B are absorption surfaces on the side surfaces, and 6A and 6B are absorption surfaces. The colored layer is provided, 7 is the bottom of the prism, and 8 is the illumination placed behind.

In the figure, Ψ ₁ and Ψ ₂ are angles formed by the bottom surface of the side surface of the prism having a triangular cross section, H ₀ is the height from the bottom surface to the top of the prism, and H ₁ and H ₂ are the bottom surfaces of the prism. To the lower end of the absorption surface, W represents the width of the bottom surface.

The prism having a triangular cross section according to the present invention is a prism having a triangular prism shape, and the angles Ψ (Ψ ₁ , Ψ ₂ ) formed by the two side surfaces and the bottom surface are both 65 ° ≦ Ψ ≦ 90.
And at least one of the angles is not 90 °, a prism or a cone-shaped prism, and the side surface of the cone-shaped prism is a surface orthogonal to the side surface and orthogonal to the bottom surface. The angle Ψ between the bottom and the bottom is 65 ° ≦ Ψ ≦
A prism with 90 ° and at least one of which is not 90 ° can be used.

The pyramidal prism is usually a quadrangular pyramid, but it may be a triangular pyramid or a hexagonal pyramid as long as they are connected. However, if it is a pixel having a dot matrix shape, a conical prism having a bottom surface shape of the pixel may be used. In this case, strictly speaking, it is not a continuous prism that covers the entire back surface of the transmission / scattering optical element,
A prism having a conical shape can also be used because it may be a prism that covers the entire area of the pixel.

Among them, from the viewpoint of the viewing angle, it is preferable that 65 ° ≦ Ψ ≦ 87 °, and it is particularly preferable that 75 ° ≦ Ψ ≦ 87 °.

This absorption surface is provided near the top of each side surface, and in this vicinity, it is preferable that H ₁ / H ₀ and H ₂ / H ₀ are 30 to 70%. That is, in the case of a prism having a triangular prism shape, the range is the two sides thereof, and in the case of a prism having the shape of a quadrangular pyramid, the range is the above range. Normally, we want to make the viewing angle symmetrical from the front, so we can use the angles Ψ ₁ , Ψ
₂ in the same, the absorbing surface may range also preferably be the same in each side.

The absorbing surface is only required to absorb the light that has reached the surface, and may be manufactured, for example, by applying a colored layer. Further, a reflection layer facing outward may be formed on the outer surface of the outer surface to effectively use the light of the illumination behind.

From the viewpoint of brightness, it is preferable that the projected area of the absorption surface onto the bottom surface is 50% or less of the area of the bottom surface.
In particular, when the cross section is trapezoidal, it is difficult to provide a reflective layer on the absorption surface to effectively utilize light, and therefore it is preferably 50% or less.

If the range of the absorption surface is the same for each side surface, the prism itself can be easily manufactured. For example, in the case of a prism having a triangular prism shape or a prism having a pyramidal shape, it is possible to use The prism can be manufactured by dipping the prism to the specific position with the top facing downward.

FIG. 2 shows a sectional view of a transmission / scattering type optical device using a prism having a trapezoidal section according to the present invention.

In FIG. 2, 11 is a transmission / scattering type optical element,
12 is a prism having a triangular cross section disposed behind the transmission / scattering type optical element, 13 is an observer, 14A and 14B are side surfaces of the prism, 14C is the upper surface of the prism, 15 is the absorption surface of the upper surface, 16
Is a colored layer provided on the absorption surface, 17 is the bottom surface of the prism, and 18
Represents the light placed behind. Note that Ψ, H ₀ , H ₁ , and H ₂ in the figure are the same as in the case of FIG. 1 except that they are the heights from the bottom of the intersection points when H ₀ extends along the side surface. is there.

In this case, the prism having a triangular cross section is a polygonal prism having a notch near the top. In this example, the shape is such that it is cut along a plane parallel to the bottom surface, and the cross section is trapezoidal. This cutting position is represented by H ₁ and H ₂ and has the range as described above. Therefore, it is possible to make H ₁ and H ₂ different from each other so that the upper surface is inclined. However, also in this case, it is preferable that the viewing angle be symmetrical from the front and that the cross section be trapezoidal because the manufacturing is easy.

It should be noted that the expression "cutout" is used here for convenience of explanation, but this does not mean that there is a step of cutting, and is merely used to show the formed shape. It is clear that such a shape may be manufactured by casting, pressing, injection molding or the like.

In addition, in an intermediate form between FIG. 1 and FIG. 2, for example, in the prism of FIG. 2, the absorption surface is formed not only on the upper surface but also on a part of the side surface, or the upper surface is not flat and the conical shape is formed. It may be formed in a body shape or a spherical shape.

In the above description, an example has been described in which the illumination is mainly arranged behind and the incident light from behind is used. However, the present invention can also be used as a reflective display device by arranging illumination on the viewer side. In this case, a reflection surface that is a reflection surface for the inside of the prism is provided on the side surface of the prism that is not the absorption surface. However, in the case of pixels in a dot matrix, it is preferable to match the shape of the pixel with the shape of the bottom surface of the prism in order to prevent the brightness of the specific pixel from changing due to the scattering state of the adjacent pixels.

In the transmission / scattering type optical element of the present invention whose light scattering characteristic changes in response to an external input, the characteristic of the transmission / scattering optical material layer changes in accordance with an external input such as voltage, heat or magnetic field. Known optical elements that are in a transmission state and 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, and the like are used. is there.

In particular, the liquid crystal optical element using the latter liquid crystal resin composite in the transmission / scattering optical material layer has excellent scattering performance, requires no alignment treatment, and is not in a liquid state, so substrate gap control is easy and easy to manufacture. In addition, it is easy to increase the size.

A prism having a triangular cross section is arranged behind the transmission / scattering optical material layer of the transmission / scattering type optical element.
In the case of a triangular prism, one of the side surfaces of the triangular prism is used as a bottom surface and is closely attached to the back surface of the transmission / scattering type optical element, and the other two
Turn one side to the back. The intersecting line of these two side faces serves as the apex, and absorption surfaces are formed on both side faces in the vicinity thereof. In the case of a cone-shaped prism, its bottom surface is brought into close contact with the back surface of the transmission / scattering type optical element, and each side surface near the top of the prism serves as an absorption surface.

The prism having a triangular cross section is
The shape may be cut out near the top.

The side surface of the prism having a triangular cross section, which is not an absorption surface, totally reflects the light incident from the viewer side in a viewing angle range. Most of the light reflected on this side surface reaches the absorption surface on the side surface or the upper surface.

FIG. 5 is a sectional view showing this state.
The oblique incident light from the observer side indicated by the arrow is reflected at the side surface of the prism at an incident angle less than a specific incident angle determined by the prism, and the reflection is repeated until finally the absorbing surface 45.
To reach.

As a result, when viewed from the observer's side, in the transmission part of the transmission-scattering type optical element, light travels straight, and on the side surface of the prism, an angle within a specific incident angle range determined by the refractive index of the prism. The light incident on is totally reflected and is absorbed by being incident on the absorption surface near the top or directly on the absorption surface. For this reason, almost no light reaches the observer side in the transmissive portion.

On the other hand, in the present invention, when the illumination is arranged behind the transmission / scattering type optical element, the light from the illumination from the back is
The light enters from the side surface of the prism that is not the absorption surface, that is, the side surface near the pedestal of the prism, and then enters the transmission / scattering type optical element.
In this case, all of the incident light is emitted from the transmission / scattering optical element surface to the viewer side at an angle within a specific angle determined by the tilt angle of the side surface of the prism and the refractive index. This incident light is not directly transmitted to an observer within the viewing angle range defined thereby.

For this reason, if the absorbing surface is made black as described above, almost no light reaches the observer,
It will look black. However, by setting the color of the absorbing surface to red, blue, green, or the like other than black, only light of that color returns, so that color is recognized.

On the contrary, in the scattering portion of the transmission / scattering type optical element, the light incident from the observer side is scattered as it is, and the light from the back illumination is obliquely incident from the side surface of the prism,
Similarly scattered. Of the scattered light, the light traveling toward the observer side is recognized by the observer as white.

As a result, black or a specific color and white display can be obtained. In this case, in order to obtain a black display on a white background by using a liquid crystal optical element that controls transmission-scattering by applying a voltage, it is necessary to use a liquid crystal optical element that is in a scattering state when no voltage is applied. .. For this, a liquid crystal optical element using a liquid crystal resin composite in which the liquid crystal described above is dispersed and held in a cured product matrix is optimal.

In addition, when the color of the colored layer on the absorbing surface is changed to a color other than black, for example, red, white and red display can be obtained.
In addition to this, if the color of the light behind is blue, a dark purple and blue display can be obtained.

The size of the absorption surface of the prism having a triangular cross section may be appropriately determined depending on the wide viewing angle and the brightness, but as described above, it is generally 30 to 70% of the height H ₀ of the prism on the top side. It may be a degree. When the prism has a trapezoidal cross section, the height of the surface to be cut may be about 30 to 70% of the height H ₀ of the prism on the top side.

Illumination used in the present invention includes well-known illuminations such as tungsten lamps, halogen lamps, metal halide lamps, xenon lamps, cold cathode discharge tubes, hot cathode discharge tubes, LEDs, EL, sunlight, and indoor lighting. It is also possible to use such a device by guiding external light such as. Further, if necessary, a combination of a plane mirror, a spherical mirror, an ellipsoidal mirror, a reflecting mirror such as a parabolic mirror, a lens, and a light guide means such as an optical fiber can be used.

The transmission-scattering optical element of the transmission-scattering optical device of the present invention is artificially transmitted by the transmission-scattering optical material layer.
Any material that can control scattering can be used. Among them, those using liquid crystal are preferable because of low power consumption and high reliability. In particular, a liquid crystal cured product composite layer in which a liquid crystal is dispersed and held in a cured product matrix is sandwiched between a pair of substrates with electrodes, and the scattering state and the transmission state can be controlled by applying a voltage. ..

As the liquid crystal cured product composite layer of the transmission / scattering type optical element sandwiching the liquid crystal cured product composite layer, any liquid crystal in which a liquid crystal is dispersed and held in a cured product matrix can be used. Specifically, the liquid crystals may form independent liquid bubbles and are enclosed in microcapsules, or the liquid bubbles may be in communication with each other, or the pores of a cured product matrix having a large number of fine pores. The part 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 applied state of the voltage, and the liquid crystal is cured. The relationship between the refractive index of the material matrix and the refractive index of the liquid crystal changes, and when the refractive indexes of the two match, the transmission state (incident light goes straight) and when the refractive indices differ, the scattering state (incident light remains unchanged) Scatter without going straight).

Specifically, in the state where voltage is applied,
The index of refraction of the cured product that constitutes the cured product matrix is made to match the ordinary refractive index (n _o ) 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 property of this element is higher than that of a conventional DSM (dynamic scattering mode) transmission / scattering type optical element, a high on / off ratio can be obtained.

The liquid crystal cured product composite layer is usually prepared by preparing a mixture of liquid crystal and a raw material for a cured product matrix, and casting and supplying the mixture onto an electrode substrate to cure the mixture, or a pair of liquid crystal cells as in a normal liquid crystal cell. Seal the periphery of the substrate with electrodes with a sealing material,
It suffices to inject the mixture from the injection port and cure the mixture so that the liquid crystal is dispersed and held in the cured product matrix.

As the cured product matrix, there are a resin matrix, a ceramic matrix and the like, but it is preferable to use the resin matrix because it is easy in the manufacturing method and the refractive index can be easily adjusted.

Among them, a photocurable resin or a thermosetting resin which is curable in a closed system is used as a raw material of the resin matrix, and a solution obtained by dissolving this in a liquid crystal is used to perform photocuring or heat curing to produce a resin matrix. Since it has good properties, both of the above-mentioned casting method and the injection method can be applied. In particular, a production method in which a photocurable resin is used and photocured is preferable.

By curing this device with a sufficiently high voltage applied only to a specific portion during this curing step, or by curing it with heating above the phase transition point of the liquid crystal. It is also possible to make that part always in a light transmitting state. Also, by applying an intermediate voltage to cure, or by semi-curing with a sufficiently high voltage applied, and then completing the curing without applying a voltage, any intermediate tone It is also possible to obtain a display of (the scattering degree at the time of scattering is an arbitrary scattering degree). As a result, it is possible to partially perform fixed display of frames, characters, etc., or display photographic images.

It is preferable to use a transmission / scattering type liquid crystal optical element in which the refractive index of this cured product matrix and the ordinary refractive index (n _o ) of the liquid crystal used are matched, and to match them completely. , It is possible to use it as long as they substantially match so that the transmission state is not adversely affected. This is because the resin matrix swells due to the liquid crystal and is closer to the refractive index of the liquid crystal than the original refractive index of the resin matrix itself, and even if there is a difference of this degree, almost all the light is transmitted. Is.

In order to use this transmission / scattering type optical element for display, the electrodes may be patterned in a desired pattern. However, various active elements such as thin film transistors (TFTs) are arranged in each pixel, and various elements are formed depending on a set of dots. The display may be displayed.

This electrode is normally a transparent electrode on both substrates, but an opaque electrode made of metal or the like may be provided together with a part of the transparent electrode.

In the present invention, a protective plate such as a glass plate or a plastic plate may be laminated on the front side or the back side of the transmission / scattering type optical element, or a color filter may be laminated to adjust the color, or individual display may be performed. In order to make the pattern multicolored,
A color filter or color illumination may be used.

The raw materials for the cured product matrix forming the liquid crystal cured product composite layer, particularly the resin matrix, include monomers and oligomers of various resins, polymers dissolved by a solvent, and the like, which are mixed with liquid crystals to form a mixture. Is used. In this case, it is preferable to use one in which the raw material of the matrix of the cured product is dissolved in the liquid crystal to form a homogeneous solution, but one in the form of latex can also be used.

When casting and supplying the mixture onto the substrate,
Although it is possible to use a solvent that distills off the solvent or one that generates by-products such as gas during curing, when injecting liquid crystal into the cell for post-curing, it is not necessary to distill the solvent in a closed system to cure. Occasionally, a curable mixture is used without generating by-products such as gas.

Therefore, as described above, it is preferable to use the photocurable resin from the viewpoint of productivity, and it is particularly preferable to use the photocurable vinyl resin. Specifically, a photocurable acrylic resin is exemplified, and a resin containing an acrylic oligomer that is polymerized and cured by light irradiation is particularly preferable.

The liquid crystals used in these cases include nematic liquid crystals, smectic liquid crystals and the like, and they may be used alone or as a composition. However, in order to satisfy various required performances such as operating temperature range and operating voltage, the composition is required. It can be said that it is advantageous to use objects. In particular, the use of nematic liquid crystal is preferable.

When a photocurable resin is used as the liquid crystal used in the liquid crystal cured product composite layer, it is preferable that the photocurable resin is uniformly dissolved, and the cured product after light exposure is dissolved. When the composition is used, it is desirable that the solubility of each liquid crystal is as close as possible.

When the liquid crystal cured product composite layer is produced, the raw material of the cured product matrix and the liquid crystal are mixed so that the ratio of the cured product matrix and the liquid crystal is about 25:75 to 75:25. It suffices to use it as a viscous material without the liquid.

In the case of producing a liquid crystal cured product composite layer, cells can be formed and injected from an injection port as in the conventional ordinary liquid crystal display element. By supplying the mixture with the liquid crystal and superposing the opposing substrates, the transmission / scattering type optical element can be manufactured with extremely high productivity.

The inter-substrate gap can be operated at 5 to 100 μm, but in the case of the liquid crystal cured product composite layer, it is set to 7 to 40 μm in consideration of the applied voltage and the contrast at the time of on / off. It is appropriate to set.

In this transmission / scattering type liquid crystal optical element, a dichroic dye, a simple dye or a pigment may be added to the liquid crystal, or a colored product may be used as a cured product matrix.

By using a plastic substrate as a substrate with electrodes, a long transmission / scattering type optical element using a continuous plastic film can be easily manufactured. Further, since the transmission / scattering type optical element of the present invention is generally about the same size as a normal liquid crystal display element, a cell is formed and injected using a glass substrate as in a normal liquid crystal display element. Even if it does so, there is almost no decrease in productivity.

By thus forming the transmission / scattering type liquid crystal optical element using the liquid crystal cured product composite layer, the risk of short circuit between the upper and lower transparent electrodes is low, and the liquid crystal display element is a normal TN type liquid crystal display element. Further, it is not necessary to strictly control the orientation and the substrate gap, and a transmissive-scattering type liquid crystal optical element capable of controlling the transmissive state and the scattered state can be manufactured with extremely high productivity.

In this transmission / scattering type liquid crystal optical element, when a voltage is applied for driving, an AC voltage which changes the alignment of the liquid crystal may be applied. Specifically, 5 to 100V
Then, an AC voltage of about 10 to 1000 Hz may be applied. Also,
A lens, a prism, a filter or the like may be arranged on the observer side of the transmission / scattering type optical element to change the viewing angle or the color.

[0082]

In the case as shown in FIG. 3, when the observer changes the position counterclockwise from the front direction, the straight traveling light hits the side surface 24 and is reflected and hits the absorbing surface 25 in the transmitting portion, or
It comes into direct contact with the absorption surface 25. Therefore, if the structure as shown in the example of FIG. 3 is adopted, the viewing angle of the observer is up to a position close to 90 ° in the downward direction.

On the contrary, when the position of the observer is changed to the upper side in the clockwise direction, the straight-ahead light strikes the side face 24 and the specific reflection corresponding to the critical angle for total reflection determined by the prism and the refractive index of the air behind is observed. When the angle is reached, the side face 24 does not undergo total reflection and goes out to the back. On the other hand, in this case, since the light from the back illumination is also incident, the light of the back illumination is directly visible to the observer, which makes it difficult to see.

In the part where the transmission / scattering optical material layer of the transmission / scattering type optical element 21 is in the scattering state, both the light incident from the observer side and the light from the illumination behind are scattered, and the observer has almost no relation to the position thereof. You will see scattered light and it will appear white.

As a result, white and black displays are obtained, the lower part is up to about 90 °, and the upper part is up to a specific angle determined by the prism and the refractive index of the air behind, specifically, 5 to 20.
You will be able to see up to about °, and the center of the viewing angle will not come in the front direction. Moreover, as described above, only about 30% of the omnidirectional incident light from the back can be effectively used.

Also in the case of the prism of FIG. 4, since the apex angle is 90 ° and only one side surface is the entire absorption surface, the viewing angle is not substantially symmetrical. On the other hand, in the case of FIGS. 1 and 2 of the present invention, the viewing angle of the observer is substantially symmetrical from the front direction.
When a prism having a triangular prism shape whose cross section is an isosceles triangle is used, the viewing angle in the left-right direction is almost the entire area, and the viewing angle in the up-down direction has an equal or substantially equal viewing angle of about ± 30 to 40 °. The operation will be described with reference to FIG.

FIG. 5 is a cross-sectional view showing the propagation state of light when the prism 42 having a trapezoidal cross section is used. Light 50 that is incident from the transmission / scattering type optical element 41 to the prism 42 side at an angle of a specific incident angle θ or less when viewed from the normal direction becomes light 50A propagating inside the prism and is reflected by the side surfaces 44A and 44B. It becomes light 50B, 50C, 50D, and finally reaches the absorption surface 45.
Also, light with a smaller incident angle θ reaches the absorption surface 45 after a smaller number of reflections or directly. Only in these cases is light reflected very little. Since light does not enter the prism from the outside at this total reflection angle,
Since light is directly incident from behind and does not go backwards, it looks black.

On the other hand, light having a certain incident angle or more goes out from the side surface of the prism. Therefore, the light from the outside also enters the inside, and the observer located at this viewing angle can directly see the illumination behind, and does not appear black.

Also, when the prism of FIG. 1 is used instead of the prism of FIG. 2, the operation is almost the same. Therefore, the prism shown in FIG. 2 has a shorter depth and a smaller area of the absorption surface, which is preferable because it is compact and easy to manufacture.

Further, among the side surfaces of the prism, a portion other than the absorbing surface can be covered with a reflecting surface for the inside of the prism to be used as a reflection type display device. In this case, light from the observer side with a certain incident angle θ or less reaches the absorption surface 45 and is absorbed, as in the case where the reflection surface is not provided.
On the contrary, light exceeding the incident angle θ is also reflected by the side surface of the prism, and therefore, it is repeatedly reflected and emitted to the observer side.

In this case, since this emission angle is emitted to the region corresponding to the incident angle, the observer located in the viewing angle region corresponding to the incident angle θ or less does not see the illumination but looks black. However, an observer located in the viewing angle range corresponding to the incident angle θ or more sees the illumination and does not appear black. This allows the pixel to appear black if it is in the transmissive state. Further, if the pixel is in the scattering state, the light returned from the prism side is also scattered again, and the display becomes brighter.

FIG. 6 is a cross-sectional view showing a state in which an outward reflection layer for effectively utilizing the light of the back illumination is formed on the absorption surface. In this example, an outward reflection layer 59 is provided on the outer surface of the colored layer 56 of the absorption surface 55, and the light 60 from the back illumination is reflected by the reflection layer and the prism side surface inside the prism does not have an absorption layer. Incident on. This improves the utilization efficiency of the illumination behind and enables bright display.

FIGS. 7A, 7B, 7C and 7D are sectional views showing another example of the present invention. FIG. 7 (A) is an example in which Ψ ₁ > Ψ ₂ , and since the absorption surfaces 61 and 62 are formed at the same position (H ₁ = H ₂ ), the viewing angles are not completely symmetrical. In order to make it more symmetrical, the lower end positions H ₁ and H ₂ of the absorption surface are made asymmetric.

FIG. 7 (B) shows a prism having a notch parallel to the bottom near the top, that is, a prism having a trapezoidal section.
This is an example in which the absorption surfaces 63, 64, 65 use prisms extending not only to the upper surface but to both side surfaces. Also in this case, H ₁ and H ₂ are 30 to 70% as described above with respect to the distance H ₀ from the bottom surface to the apex extending from both side surfaces.

FIG. 7C shows an example of a shape which is not parallel to the bottom surface in the vicinity of the top portion, and the cut surface serves as the absorbing surface 66. Also in this case, for the distance H ₀ from the bottom surface to the apex extending on both sides, H ₁ and H ₂ are 30 to 30% as described above.
70% In this example, an outward reflecting surface 71 is formed on the absorbing surface 66.

FIG. 7D shows another example of the shape in which the bottom surface is cut out non-parallel to the bottom surface, and the cutout surface has a chevron shape, and the cutout surfaces are absorption surfaces 67 and 68. Has been done.
Again, in this example, the outwardly reflecting surfaces 72, 7 on the absorbing surfaces 67, 68.
3 is formed. In addition to this, the mountain-shaped surface of (D) may have an arc cross section, and a prism having a shape obtained by combining the above examples may be used.

[0097]

EXAMPLES The present invention will be specifically described below with reference to examples. Examples 1 to 4 Two glass substrates provided with electrodes made of ITO that were patterned so as to be able to display the letters of the day were used, and the periphery was sealed with a sealing material with a spacer of 20 μm interposed therebetween to prepare an empty cell. ..

2-Ethylhexyl acrylate 7 parts and 2-
15 parts of hydroxyethyl acrylate, 24 parts of acrylic oligomer (“M-1200” manufactured by Toagosei Co., Ltd.), 0.9 part of “Darocurer 1116” manufactured by Merck as a photo-curing initiator and “E-8” manufactured by BDH as a liquid crystal. Was uniformly dissolved in 64 parts to prepare a liquid crystal mixture.

This liquid crystal mixture was injected into the above-mentioned empty cell and irradiated with ultraviolet rays for 30 seconds to be exposed to produce a transmission / scattering type liquid crystal optical element. In this transmission / scattering type liquid crystal optical element, the cured resin forming the resin matrix has a refractive index substantially equal to the ordinary refractive index (n _o ) of the liquid crystal, so that no voltage is applied. Then, the refractive indexes of the two were different, and the whole was in a scattering (white turbid) state. When an AC voltage (AC35V, 50Hz) was applied between the desired electrodes, only that part was in a transparent state.

Acrylic prism made of a triangular prism whose cross section is Ψ ₁ = Ψ ₂ = 86 ° and isosceles triangle (refractive index = 1.50, bottom width W = 10 mm, distance from bottom to top H ₀ = 71.5 mm) Paint the area near the top of the (H ₁ = H ₂ = 37mm) black on both sides,
It was used as an absorption surface.

When this prism was brought into close contact with a transmission / scattering type liquid crystal optical element as shown in FIG. 1 and the visual angle was examined, the horizontal direction, which is the axial direction of the column, was approximately ± 90 °, and the vertical direction was approximately ± 90 °. It was 30 °. Also, the brightness was about 50% of the brightness of the scattering part when the prism was not arranged when illuminated by parallel rays from the back. Table 1 below shows an example in which prisms of the same material are used and the shape is changed.

[0102]

[Table 1]

The example 1 corresponds to the example described in FIG. 5 in which the number of reflections is 4 or less, and the examples 2 to 4 respectively show the number of reflections.
Examples are 3 times or less, 2 times or less, and 1 time or less.

Examples 5 to 8 Table 2 shows the results of examining the viewing angle by using a lead glass prism (refractive index = 1.84) having a high refractive index instead of the acrylic prism of Example 1.

[0105]

[Table 2]

The fifth embodiment corresponds to the example in which the number of reflections is 5 or less as described with reference to FIG. 5, and the sixth to eighth embodiments respectively show the number of reflections.
Examples are 4 times or less, 3 times or less, and 2 times or less.

Examples 9 to 16 When a prism having a reflecting layer formed on the outer surface of the colored layer of the absorbing surface of Examples 1 to 8 was used, the utilization of light from the back was increased, and no reflecting layer was formed. It became brighter than usual.

Examples 17 to 24 In place of the triangular prisms of Examples 1 to 8, prisms having square bases and symmetrical pyramidal prisms having absorption surfaces near the tops of the four side surfaces were used. Table 3 shows the results of the examination of the visual angle using the above.

[0109]

[Table 3]

As a result, the viewing angle in the left-right direction was the same as that in the up-down direction as compared with Examples 1 to 8, but the brightness was significantly improved.

Embodiments 25 to 32 Embodiments 1 to 8 have a triangular cross section in which the absorption surface is formed, and the portion where the absorption surface is formed is cut out parallel to the bottom surface, that is, the cross section shown in FIG. The prism was formed, and the colored layer was formed on the upper surface thereof.

Using this trapezoidal prism,
When evaluated in the same manner as in Example 8, the visual and brightness were evaluated in Example 1 to
Since it is equivalent to 8, and the depth is H ₁ (= H ₂ ), the depth required for mounting was greatly reduced and it was easy to downsize. Further, even when the non-directional backlight was used, the brightness was not lowered because the number of shadows by the absorbing surface of the prism tip portion was small as compared with Examples 1 to 8.

Embodiments 33 to 40 In Embodiments 17 to 24, the portion where the absorption surface of the prism having a triangular cross section is formed is cut out in parallel with the bottom surface, that is, the cross section as shown in FIG. 2 is trapezoidal. The prism was formed, and the colored layer was formed on the upper surface thereof.

Using this trapezoidal prism, Example 17-
When evaluated in the same manner as in Example 24, the visual sense and brightness were evaluated in Example 17 to
Since it is equivalent to 24 and the depth is H ₁ (= H ₂ ), the depth required for mounting was greatly reduced and it was easy to miniaturize. In addition, even when the non-directional backlight was used, the brightness was not decreased because the shadow of the absorbing surface of the prism tip portion was less than that in Examples 17 to 24.

Examples 41 and 42 Instead of the prism of Example 32, Ψ ₁ = 75.6 °, Ψ ₂ = 90 °
And the bottom width W = 10 mm, the distance from the bottom to the top H ₀ =
(39 mm) has a notched shape near the top of H ₁ = H ₂ = 14 mm, and its upper surface is painted black to make it an absorbing surface. In this case, the viewing angle is 57 ° in the upward direction and 30 ° in the downward direction, the brightness is 37% in the case of a prism having a triangular prism shape, and the brightness is 37% in the case of a prism having a quadrangular pyramid shape. It was 59%.

Example 43 Instead of the prism of Example 1, Ψ ₁ = 84.2 °, Ψ ₂ = 78.5
°, bottom width W = 10 mm, distance from bottom to top H ₀
= 32.8 mm) near the top (H ₁ = 16.7 mm, H ₂ = 14.1 mm) was painted black on both sides to make it an absorbing surface. When using this prism, the viewing angle is 30 ° both up and down, and the brightness is 45
%Met.

Example 44 The prism of Example 43 was changed to H ₁ = 16.7 as shown in FIG. 7 (C).
mm, H ₂ = 14.1 mm, the notch was cut out, and the oblique upper surface was painted black to make it an absorption surface. Further, an aluminum reflective layer was formed on the absorbing surface. The viewing angle when this prism was used was equivalent to that in Example 43. Also, the brightness was about 45%, which was about the same for parallel light and omnidirectional light.
The brightness was further improved in a room with a lot of light incident from above.

Example 45 Instead of the prism of Example 25, as shown in FIG. 7 (B), notch positions were set to 45 mm instead of H ₁ = H ₂ = 37 mm, and the entire upper surface and side surface H _The absorption surface was used up to the position of ₁ = H ₂ = 37 mm. Furthermore, the absorption surface was covered with white paint.
Even when this prism was used, the viewing angle was equivalent to that of Example 25, but the brightness was further improved.

Example 46 Instead of the prism of Example 25, as shown in FIG. 7D, the notch position was H ₁ = H ₂ = 37 mm, and the peak portion was 45 mm.
mm, and the entire upper surface of the two was used as an absorption surface. Even when this prism is used, the viewing angle and brightness are the same as those in Example 25.
Was equivalent to.

Example 47 Instead of the transmission / scattering type liquid crystal optical element provided with the electrode made of ITO patterned for displaying the Japanese character, the TF of each pixel was used.
A transmission / scattering liquid crystal optical device was obtained using a matrix-shaped transmission / scattering liquid crystal optical element having T (thin film transistor) formed therein.

The prism has a square bottom surface,
It is a symmetric quadrangular pyramid acrylic prism with an angle Ψ
₁ (= Ψ ₂ ) = 81 ^o , H ₀ = 3.16 mm, H ₁ (= H ₂ ) = 1.4 mm, W
= 1 mm. As shown in FIG. 2, a prism having a notched surface parallel to the bottom surface as an absorption surface was used.

The viewing angle of this display device was about ± 30 ° in both vertical and horizontal directions, and the display contrast ratio was about 10. Brightness is the case of illumination with parallel rays from behind,
It was about 65% of the brightness of the scattering part when the prism was not arranged.

Example 48 The transmission / scattering liquid crystal optical element of Example 47 was used, and only the prism was replaced. The prism shape is an acrylic prism with a triangular prism shape whose cross section is an isosceles triangle, and the angle Ψ ₁ (= Ψ
₂ ) = 85 ^o , H ₀ = 5.7 mm, H ₁ (= H ₂ ) = 1.4 mm, W = 0.5 m
m. As shown in FIG. 1, a prism having absorption surfaces on both side surfaces near the top of the prism was used.

The viewing angle of this display device is approximately ± 30 ° in the vertical direction,
A horizontal contrast of ± 90 ° and a display contrast ratio of about 10 were obtained. The brightness is about 48 times the brightness of the scattering part when the prism is not arranged when illuminated by parallel rays from the back.
%Met.

Example 49 The side surface of the prism of Example 47 is covered with an aluminum reflective layer,
Light was applied from the front of the liquid crystal optical element to obtain a pure reflection type display device. The viewing angle is approximately ± 30 both vertically and horizontally.
The contrast ratio was about 10. The brightness is
When illuminated by parallel rays from the observer's side, the brightness was about 6 times the brightness of the scattering area without the prism.

However, when the pixels of the transmission-scattering type liquid crystal optical element and the prisms do not have a one-to-one correspondence, the display state of adjacent pixels is influenced during driving. Therefore, the quality of gradation display was slightly inferior to that of Example 47. However, when the pixels and the prisms have a one-to-one correspondence, the influences of the display states of the adjacent pixels are hardly affected.

[0127]

As described above, according to the present invention, a transmission / scattering type optical element capable of electrically controlling the scattering state and the transmitting state and a part of the vicinity of the apex having a triangular cross section or a triangular cross section are provided. This is a notched prism, and the angles Ψ ₁ and Ψ ₂ formed by the two side surfaces of the prism with respect to the bottom surface are 65
° ≤ Ψ ₁ ≤ 90 ° and 65 ° ≤ Ψ ₂ ≤ 90 °, at least _one of Ψ ₁ and Ψ ₂ is not an angle of 90 °, and the prism with the absorption surface near the top of the prism and illumination By combining and, the viewing angle of the observer is almost in the front direction, the light amount loss of illumination is small, a bright display can be obtained, and a high contrast ratio can be obtained.

As the illumination, an ordinary backlight can be used, or external light can be used. In addition, a reflector,
By supplying light with strong directivity in combination with a lens or the like, a brighter display is possible.

In particular, by forming a shape in which the vicinity of the top of the prism is cut out, the depth can be small, 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 laptop computers, word processors, and televisions.

Further, in the transmission / scattering liquid crystal optical element using the liquid crystal resin composite in which the liquid crystal is dispersed and held in the cured product matrix, the incident light is absorbed because the transmission-scattering is controlled by controlling the refractive index. However, it is usually more than twice as bright as a conventional TN type liquid crystal display element, and even when a high light quantity is incident,
Also, the temperature of the transmission / scattering type optical element hardly rises and the reliability is high.

In addition to the above, the present invention can be applied in various ways within a range that does not impair the effects of the present invention.

[Brief description of drawings]

FIG. 1 is a sectional view showing a basic configuration of a transmission-scattering type optical device of the present invention.

FIG. 2 is a cross-sectional view showing a basic configuration of a transmission / scattering type optical device of the present invention.

FIG. 3 is a cross-sectional view showing an example of a conventional transmission / scattering type optical device.

FIG. 4 is a cross-sectional view showing an example of a conventional transmission / scattering type optical device.

FIG. 5 is a cross-sectional view illustrating the progress of light in the transmission / scattering type optical device of the present invention.

FIG. 6 is a cross-sectional view illustrating the progress of light in the transmission / scattering type optical device of the present invention.

FIG. 7 is a cross-sectional view of another example of the transmission-scattering type optical device of the present invention.

[Explanation of symbols]

Transmission / scattering type optical element: 1, 11, 21, 31, 41, 51 Prism: 2, 12, 22, 32, 42, 52 Observer: 3, 13 Side surface: 4A, 4B, 14A, 14B, 24, 34, 44A, 44B, 5
4 Absorption surface: 5A, 5B, 15, 25, 35, 45, 55, 61-68 Coloring layer: 6A, 6B, 16, 56 Bottom surface: 7, 17, 27, 37 Illumination: 8, 18 Reflective layer: 59, 71, 72, 73

Claims (7)

[Claims] 1. A prism is provided behind a transmission / scattering optical material layer of a transmission / scattering optical element whose light scattering characteristics change in response to an external input, and a bottom surface of the prism is in close contact with a back surface of the transmission / scattering optical element. In the arranged transmission and scattering type optical device,
The prism is a prism having a triangular cross section or a shape in which a portion near the top of the triangle is cut away, and the angles Ψ ₁ , Ψ ₂ formed by the two side surfaces of the prism with respect to the bottom surface.
Is 65 ° ≦ Ψ ₁ ≦ 90 ° and 65 ° ≦ Ψ ₂ ≦ 90 °, and at least _one of Ψ ₁ and Ψ ₂ is not 90 °, and the vicinity of the top of the prism is the absorption surface. A transmission / scattering type optical device. 2. The transmission / scattering type optical device according to claim 1,
A transmission-scattering type optical device characterized in that the prism having a triangular cross section is a prism having a triangular prism shape, and 65 ° ≦ Ψ ₁ ≦ 87 ° and 65 ° ≦ Ψ ₂ ≦ 87 °. 3. The transmission / scattering type optical device according to claim 1,
A prism having a triangular cross section is a cone-shaped prism, and all angles Ψ formed by the side surface and the bottom surface on a surface orthogonal to the side surface of the cone-shaped prism and perpendicular to the bottom surface are 65
A transmission / scattering type optical device characterized in that: ° ≦ Ψ ≦ 87 °. 4. The transmission / scattering type optical device according to claim 1, wherein the prism having a triangular cross section is a polygonal prism having a shape cut out near its apex. A transmission / scattering type optical device characterized in that the notched surface of the is an absorption surface. 5. The transmission / scattering type optical device according to claim 1, wherein the height from the bottom surface to the top portion of the prism having a triangular cross section is H ₀ , and the height from the bottom surface to the lower end of the absorption surface. Are H ₁ and H ₂ , respectively, 0.30 ≤ H ₁ / H ₀ ≤ 0.70 and 0.30
A transmission / scattering type optical device characterized in that ≦ H ₂ / H ₀ ≦ 0.70. 6. A transmission / scattering optical device according to claim 1, wherein an illumination is arranged behind the prism. 7. A transmission / scattering type display device using the transmission / scattering type optical device according to claim 1 for a display device.