JPH04142528A - Projection type display device and lighting device - Google Patents

Abstract

PURPOSE:To remove diverged light and to improve the contrast ratio of a projection image by converging the light emitted by a light source by using an elliptic mirror and increasing the convergence efficiency, and providing a prism in a specific shape at its 2nd focus position. CONSTITUTION:The light source 1 is arranged at the 1st focus position of the elliptic mirror 2 and the light emitted from the light source 1 is reflected by the elliptic mirror 2, made incident on the opening part of a stop 3 from the bottom surface of a conic prism 4 provided with its bottom surface, and projected as uniform luminous flux; and the light is collimated by a converging lens 5, a 2nd stop 8 as a means for removing scattered light removes the scattered light, and the light is projected on a screen through a projection lens 9. As shown in an extended figure of the projection light source system, the light source 21 is arranged at the 1st focus of the elliptic mirror 22 and the opening part of the stop 23 and the bottom surface of the prism 24 are arranged at the 2nd focus. The conical prism is so shaped that even incident light having the largest angle theta2 of incidence in incident light reflected by the elliptic mirror is reflected totally in the prism, and consequently a high light emission light source which is close to an ideal spot light source is obtained almost without light quantity loss.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a projection type display device using a transmission scattering type display element and a lighting device using the same.

[Prior Art] Conventionally, projection display devices have generally used CRTs, but they have had the disadvantage of being large in size. For this reason, a compact projection display device has been desired.

On the other hand, a liquid crystal display element is a flat panel display element, and is used as a variety of display devices due to its features such as being small, light, and low in power consumption.

In recent years, this liquid crystal display element has been put into practical use because it is believed that by using it in a projection type display device, a large and heavy projection type display device can be downsized.

The first one that was put into practical use used a normal TN type liquid crystal display element, and used an active matrix liquid crystal display element such as that used in liquid crystal TVs. However, since this TN type liquid crystal display element uses two polarizing plates, the loss of light is large and a bright projected image cannot be obtained.

Therefore, a flat panel display element with high transmittance during transmission is desired, and it has been proposed to use a transmission-scattering type display element that takes on a transmission state and a scattering state depending on the voltage application state.

Since this transmission scattering type display element does not use a polarizing plate, light is transmitted with almost no loss during transmission, so that a bright projected image can be obtained.

For this reason, various projection display devices using transmission scattering display elements have been proposed. However, they are traditional TN
Since the optical system of a projection type display device using a type liquid crystal display element was adopted as is, the advantage of brightness using a transmission scattering type display element could not be fully utilized.

[Problem to be Solved by the Invention J] Figures 6 (A), (B), and (C) are side views of the projection light source system proposed therein. The projection optical system and the like disposed on the side from which light is emitted from the element are omitted.

FIG. 6(A) shows a light source 71A and an elliptical or parabolic mirror 72A.
This is a projection light source system using a light condensing lens, and shows an example in which light is made to enter a transmission scattering type display element 75A without using a condensing lens. This example had the problem of requiring a large elliptical mirror or parabolic mirror. Furthermore, part of the light from the light source directly enters the transmission scattering type display element, and the light flux is different from the incident light due to reflection, and the scattered light is mixed with the original transmitted light. However, there was a major problem in that the contrast ratio deteriorated, which did not occur when a TN type liquid crystal display element was used.

FIG. 6(B) shows a projection light source system using a light source 71B, a spherical mirror 72B, and a condensing lens 74B.
4B is used to cause light to enter a transmission scattering display element 75B. In this example, although the spherical mirror may be small, it has the problem that the light from the light source is not fully utilized.

FIG. 6(C) shows a projection light source system using a light source 71C, an elliptical mirror 72C, and a condensing lens 74C, and a lens 74G is used to make light incident on a transmission scattering type display element 75C. An example is shown below. In this example, the elliptical mirror could be small and the light from the light source could also be easily utilized. However, as in the example (A), some of the light from the light source was diagonally transmitted through direct scattering. This has had a major problem in that the scattered light that enters the display element is mixed with the original transmitted light, resulting in a decrease in contrast ratio.

Furthermore, although a light source is called a point light source, it has a finite length. If elliptical mirrors like (A) and (C) were ideal point light sources, the luminous flux would be aligned, but because they have a finite length, the light diverges more and the luminous flux is aligned. It becomes difficult.

However, in a projection display device using a TN type liquid crystal display element, if strong light is applied to brighten the projected image,
Since the polarizing plate of the liquid crystal display element absorbs light and generates heat, there is a problem that the polarizing plate deteriorates and becomes unusable, and it was not possible to simply use a strong projection light source system.

On the other hand, since these transmission-scattering display elements operate by either transmitting or scattering light, there is little chance of problems caused by the light turning into heat. Of course, a slight amount of heat is generated as light is absorbed by the substrate, electrodes, etc., but it is less than the absorption by the polarizing plate, and its heat resistance is high, so it can withstand strong incident light for TN type liquid crystal display elements. It is durable and allows for bright display.

However, the transmission scattering type display element tends to have a lower contrast ratio on the screen than the TN type liquid crystal display element.

This is because in the off-section of a TN-type liquid crystal display element, no light is emitted to the side opposite to the light source, whereas in the transmission-scattering display element, light is emitted even in the off-section. The emitted scattered light is removed by means for removing scattered light placed between the transmission scattering type display element and the screen.

If this scattered light cannot be removed sufficiently, the scattered light will appear to overlap the original transmitted light on the screen, resulting in a decrease in contrast ratio.

Therefore, if the light beams incident on the transmission-scattering display element are not aligned, even if a highly accurate means for removing scattered light is provided on the output side, the display will only become dark and the contrast ratio will be difficult to improve.

For this reason, it has been desired to take advantage of the bright display of a projection display device using a transmission-scattering display element while increasing the efficiency of light source use, downsizing the device, and improving the contrast ratio.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes a projection light source system, a transmission scattering display element into which light from the projection light source system enters, and , a projection type display device having a projection optical system for projecting light emitted from the transmission scattering type display element onto a screen, a projection light source system using a cone-shaped prism whose bottom cross section is larger than the top cross section; It has an elliptical mirror, a light source, an aperture, and a condensing lens.The light source is placed at the first focal position of the elliptical mirror, and the light from the light source is condensed at the second focal position. A projection type display device, and an illumination device using the same, characterized in that only the light that has passed through the prism arranged at the focal point is focused by a condensing lens and is incident on a transmission scattering type display element. It provides equipment.

Since the projection display device of the present invention uses a transmission-scattering display element, the brightness of the display with respect to light incident on the transmission-scattering display element is bright.

Furthermore, the most important feature is that it uses a projection light source system that uses an elliptical mirror, a light source, a cone-shaped prism, and a condensing lens, so the light flux that enters the transmission scattering display element is uniform, and the light that is emitted is Scattered light can be removed with high efficiency by the means for removing scattered light provided on the side, making it possible to increase the utilization efficiency of the light source, downsize the light source, and obtain a projected image with a high contrast ratio.

In particular, as a transmission scattering type display element, a nematic liquid crystal with positive dielectric anisotropy is dispersed and held in a resin matrix between substrates with electrodes, and the refractive index of the resin matrix is the ordinary refractive index (no) of the liquid crystal used. It is preferable to use a transmission-scattering type liquid crystal display element in which a liquid crystal resin composite which is made to substantially coincide with each other is sandwiched therebetween.

Such a liquid crystal resin composite has good transmission-scattering characteristics,
Since it is in the form of a film, problems such as short circuits between substrates due to pressurization of the substrates and destruction of active elements due to movement of spacers may occur.

Note that the transmission-scattering type display element sandwiching this liquid crystal resin composite has poor multiplex drive characteristics, and therefore is usually used with an active element provided in each pixel electrode for purposes other than simple pattern display.

In addition, this liquid crystal resin composite has a resistivity equivalent to that of the conventional TN mode, and there is no need to provide a large storage capacitance for each pixel electrode as in the DS mode, making it easy to design active elements. Moreover, the power consumption of the liquid crystal display element can be kept low. Therefore, the alignment film forming process can be removed from the manufacturing process of a conventional TN mode liquid crystal display element, and therefore production is easy.

Examples of the active element include a transistor, a diode, a nonlinear resistance element, and the like, and two or more active elements may be arranged in one pixel as necessary.

The projection display device of the present invention includes a projection light source system, a transmission scattering display element, and a projection optical system.

The projection light source system of the present invention includes an elliptical mirror, a light source, a conical prism, and a condensing lens. This cone-shaped prism may be a cone-shaped prism whose bottom cross section is larger than its top cross section, and its specific shape will be described in detail later.

A light source is placed at a first focal position of the elliptical mirror, the light from the light source is focused at a second focal position, and is incident from the bottom surface of a cone-shaped prism located at the second focal position, The display element is arranged so that the light emitted from the top surface is collected by a condensing lens and made to enter the transmission scattering type display element.

Note that it is most efficient to arrange the cone-shaped prism at the second focal position, but depending on the case, it may be arranged shifted back and forth in the optical axis direction.

In the present invention, since a considerable portion of the light source is covered with an elliptical mirror, much of the light emitted from the light source can be utilized by reflection. Furthermore, like a spherical mirror, most of the reflected light returns to the light source, and there is less loss due to the light source itself not allowing the reflected light to pass through, improving light utilization efficiency. Furthermore, since a condensing lens is used, a small elliptical mirror can be used, eliminating the need for an expensive large elliptical mirror (the projection light source system can be downsized. A cone-shaped prism is placed in the cone-shaped prism.At this time, it is preferable to prevent light that reaches other than the bottom surface of the cone-shaped prism from reaching the condenser lens.Specifically, the cone-shaped prism is A diaphragm having the same opening as the bottom surface may be placed at the bottom surface of the prism.

This eliminates the misaligned light component of the light flux that is more likely to occur than with a spherical mirror using a finite length light source and an elliptical mirror, and the light component that does not go through the second focal point and goes directly to the condenser lens without being reflected, thereby aligning the light flux. This makes it possible to reduce unnecessary light that is emitted from the transmission-scattering display element and reach the screen, and to improve the contrast ratio.

In particular, this effect is great if a means for removing scattered light, specifically a second aperture, is provided between the transmission scattering type display element and the screen.

FIG. 1 is a schematic diagram of an example showing the basic configuration of a projection type display device of the present invention.

In the example of FIG. 1, the light source 1 is placed at the first focal point of the elliptical mirror 2, and the light emitted from the light source 1 is reflected by the elliptical mirror 2.
The light enters from the bottom surface of a cone-shaped prism 4 whose bottom surface is provided at the aperture of the diaphragm 3, passes through the prism, is aligned, exits from the top surface, and is condensed by a condensing lens 5. The light is converted into parallel light, passes through the transmission scattering type display element 6, is focused by a condensing lens 7, is removed by a second aperture 8 as a means for removing scattered light, and is used for projection. is projected onto a right screen (not shown) by a lens 9. The light source 1, the elliptical mirror 2, the aperture 3, the prism 4, and the condensing lens 5 constitute a projection light source system, and the condensing lens 7, the second aperture 8, and the projection lens 9 project the light. It makes up the optical system.

FIG. 2 is a side view for explaining the shape of a cone-shaped prism.

Figure 2 (A) shows a cone-shaped prism I with the simplest shape.
FIG. 3 is a side view of an example using IA, which has a truncated cone or truncated pyramid shape. In this case, the bottom surface 12A and the bottom cross section 14A of the bottom surface match, and the top surface 13A and the top surface cross section 15A of the top surface match. The bottom and top surfaces of this prism are perpendicular to the optical axis and intersect with the side surfaces of the prism at an angle ψ.

FIG. 2(B) shows an example in which the bottom surface 12B of the prism IIB is shaped like a cone, and forms an angle φ with respect to the cross section of the bottom surface. Further, on the upper surface side, the upper surface 13B is curved to form a lens, and is formed in a convex shape from the upper surface cross section 15B toward the emission side.

FIG. 2(C) is an example in which the bottom surface 12G of the prism IIG is shaped like a cone, and the top surface 13G is a microlens array formed on the top cross section 15C. This is an example in which the rod lens array is shaped like a cone and the upper surface 13D is formed on the upper surface cross section 150.

In addition, in (B) to (D), the bottom surfaces 12B to 12D are convex conical shapes, but may be concave conical shapes. Further, the side surface of the cone-shaped prism may be a curved surface other than a straight line.

FIG. 3 is an enlarged cross-sectional view of a portion of the projection light source system used in the present invention.
1, and the opening of the diaphragm 23 and the bottom surface of the prism 24 are placed at the second focal point.

The light emitted from this light source 21 is either directly or only the light that is reflected by the elliptical mirror 22 and reaches the aperture of the diaphragm 23 enters the bottom surface of the prism 24, propagates inside the prism, and exits from the top surface of the prism. It is made to be.

If the shape of such a cone-shaped prism is such that the incident light is almost completely reflected on the inner surface of the prism, the loss of light amount within the prism can be substantially eliminated. In other words, it is sufficient that the prism internally completely reflects the incident light having the maximum incident angle θ2 of the light that is reflected by the elliptical mirror and reaches the prism. For this purpose, the bottom surface of the entrance side of the prism should be made convex toward the entrance side than the bottom cross section, as shown in FIGS. It is preferable to make it into a shape.

Specifically, the prism should have a conical or pyramidal shape with its side surfaces intersecting at an angle φ with respect to the bottom cross section, and the angle φ has an optimal value depending on the position of the light source, elliptical mirror, and prism bottom. , -20° to about 20°. - For boat fishing, in order to use light efficiently, if the prism is made convex, it is preferable to arrange it so that the second focal point is located slightly outside the bottom surface of the prism; In this case, it is preferable that the second focal point be located slightly inside the bottom surface of the prism.

By making the prism have a bottom cross section>a top cross section, an effect can be obtained in which the apparent diameter of the upper aperture is made smaller.

Therefore, almost no light loss occurs, and the diameter of the upper aperture is apparently reduced (ie, a high-emission light source close to an ideal point light source is obtained).

In addition, the top surface of the prism can be made into a spherical or aspherical lens shape, the surface can be roughened by etching or polishing to make it a light-diffusing surface, an anti-reflection film can be formed, a microlens array, a rod lens array, etc. can be formed. As a result, a decrease in the amount of emitted light and non-uniformity due to reflection can be reduced. Note that it is preferable to form an antireflection film on the incident side of the prism in order to prevent incident loss.

Although this example is explained using one transmission-scattering type display element, in cases other than monochromatic display, a plurality of transmission-scattering type display elements are usually used for each color.

For example, in the case of full-color display such as a color TV display, three transmission-scattering type display elements for RGBB colors may be used. Of course, even if three color filters are incorporated into one transmission-scattering type display element, the display will be brighter than when the same TN type liquid crystal display element is used.
The projected image becomes significantly darker due to absorption of light by the color filter. For this reason, normally a guichroic mirror, a guichroic prism, etc. are used to separate the light into three colors of RGB, and the transmitted and scattered light is controlled by a transmission scattering type display element that does not have a color filter, and the transmitted light is combined and projected. It will be done like this.

FIG. 4 shows an example of this, and is a schematic diagram of an example using a gicroic mirror.

In FIG. 4, 31 is a light source, 32 is an elliptical mirror, 33 is an aperture, 34 is a prism, 35 is a condensing lens, and 41.4
Reference numeral 3 indicates a spectroscopic gicroic mirror, and reference numeral 42 indicates a mirror, which constitute a projection light source system.

37A, 37B, 37G are lenses corresponding to each color, 3
6A, 36B, 36G are transmission scattering type display elements corresponding to each color, 44.46 is a gicroic mirror for synthesis, 4
5 is a mirror, these 44 to 46, and a second diaphragm (not shown) as a means for reducing diffused light (on the right side of the figure);
The projection lens constitutes a projection optical system, which projects onto the screen on the right side of the figure.

FIG. 5 is an example of a projection display device using a reflective transmissive scattering display element.

In FIG. 5, 51 is a light source, 52 is an elliptical mirror, 60 is a mirror, 53 is an aperture, 54 is a prism, 55 is a condensing lens, and 61 is a spectral/synthesizing guichroic prism. Configure a projection light source system. 56A, 56B,
56C is a reflective transmission scattering display element corresponding to each color,
58 is a second diaphragm as a means for reducing diffused light, 59 is a projection lens, and these and a spectroscopic/synthesizing guichroic prism 61 constitute a projection optical system. projected onto the screen.

As the light source used in these projection light source systems, those having short emission length such as halogen lamps, metal halide lamps, and xenon lamps can be used.

Any elliptical mirror may be used as long as the light source can be placed at its first focal position and the bottom surface of a prism, which will be described later, can be placed at its second focal position. In addition, it is sufficient that the size is large enough to efficiently use the light from the light source. Since it is usually considered a cold mirror, its small size is a major advantage.

The prism disposed at the second focal position is used to utilize only the light that has been condensed at the second focal position and has a uniform luminous flux. In particular, it is preferable to arrange an aperture to block light except for the bottom part of the prism.Specifically, an aperture with a hole like the one shown in the example above or a small mirror is used. etc. When a small mirror is used, it is not necessary to arrange the light source and the transmission scattering type display element on a straight line.

In the case of an aperture, the hole becomes the opening, and only the light that passes through the hole is focused by the focusing lens, and in the case of a small mirror, the reflecting surface becomes the opening. , only the light reflected by the reflective surface enters the prism and is focused by the focusing lens.

The diameter of the bottom cross section of this prism (same as the diameter of the aperture if an aperture is provided) and the diameter D2 of the top cross section of the prism are determined by taking into consideration the size of the light source, desired brightness, contrast ratio, etc. That's fine.

Normally, when creating parallel light as in the example in Figure 1,
It is preferable that the ratio /f between the diameter D2 of the top cross section of the prism and the focal length f1 of the condensing lens is set to 0.02 to 0.18.

This projection light source system may be used in combination with other mirrors, optical fibers, fiber arrays, lenses, cooling systems, infrared cut filters, ultraviolet cut filters, etc. within a range that does not impair the effects of the present invention.

As the projection optical system, a conventionally known projection optical system such as a lens can be used.

This projection optical system may be configured to project only linearly transmitted light out of the light emitted from the transmission-scattering display element onto the screen, and remove scattered light.

In the simplest configuration, there is a configuration in which only a projection lens is provided immediately after the transmission scattering type display element, and a condensing lens, a reflecting mirror, etc. may be used in combination as necessary.

However, as it is, the scattered light cannot be removed sufficiently unless the projection distance is increased, which is not practical, so it is preferable to provide a means for removing the scattered light. Specifically, the transmitted light may be collected once after passing through the transmission scattering type display element, and a second diaphragm may be provided at the focal point position. As this second diaphragm, an aperture with a hole similar to the diaphragm of the projection light source system described above, a small mirror, or the like can be used.

In the case of an aperture, the hole becomes the opening, and only straight transmitted light (light that passes through the part where the pixel part is in the transparent state) can pass through the hole.In the case of a small mirror, The reflective surface becomes the opening, and only the straight-line transmitted light is reflected by the reflective surface and can pass through, and in both cases, scattered light (light scattered by the part of the pixel area that is in a scattered state) almost never reaches the focal position. Therefore, only the linear transmitted light necessary for the original image is projected.

The diameter D2 of the opening of the second diaphragm may be determined in consideration of desired brightness, contrast ratio, etc. It is also preferable to make it possible to change the size of the opening so that it can be adjusted.

When multiple transmission scattering type display elements are provided for each color,
As in the above example, the configuration may be such that the images are composited using a guichroic prism or a guiic mirror, etc., or they may be projected individually and then composited on the screen. Since there is only one optical axis, it is advantageous for small and portable applications.

Note that the means for removing scattered light may also be placed between the transmission scattering type display element and the screen, so it may be placed in the optical path after synthesis as in the example above, or it may be placed in the optical path after combining the It may be arranged with a condensing lens immediately after the scattering type display element, so that the scattered light is removed, combined, and projected.

The transmission scattering type display element of the present invention can be used as long as it is a flat type display element that can switch between a transmission state and a scattering state depending on the voltage applied state.

Specifically, it is a DSM (dynamic scattering mode) liquid crystal display element, in which liquid crystal is dispersed and held in a resin matrix, and transmission scattering is controlled by the mismatch between the refractive index of the liquid crystal and the refractive index of the resin matrix. There are liquid crystal display elements using resin composites, elements in which fine acicular particles are dispersed in a solution, and transmission scattering is controlled by applying voltage.

Among them, liquid crystal display elements using liquid crystal resin composites are
It has good scattering performance, can be manufactured using a manufacturing process similar to that of conventional TN-type liquid crystal display elements, and can be driven using the same driving IC, making it easy to use.

The liquid crystal resin composite of a liquid crystal display element using a liquid crystal resin composite consists of a resin matrix in which many fine pores are formed and liquid crystal filled in the pores, and the refraction of the liquid crystal changes depending on the voltage applied state. When the index of refraction matches the refractive index of the resin matrix, light is transmitted, and when they do not match, light is scattered.

More preferably, a nematic liquid crystal with positive dielectric anisotropy is used, and the refractive index of the resin matrix is made to almost match the ordinary refractive index (no) of the liquid crystal used, so that high transmission can be achieved when a voltage is applied. The contrast ratio of the projected image is high even without providing a light-shielding film between the pixels, as the area between the pixels without electrodes is in a scattering state (turns black when projected onto a screen). Therefore, it is preferable.

The liquid crystal resin composite consists of a resin matrix with many fine pores and liquid crystal filled in the pores.
It has a structure in which liquid crystal is sealed inside liquid bubbles like microcapsules, but individual microcapsules are not completely independent. They may communicate through a gap.

This liquid crystal resin composite is made by mixing the liquid crystal and the materials constituting the resin matrix to form a solution or latex, which is then cured by light curing, heat curing, solvent removal,
The resin matrix may be separated by reaction curing or the like, and the liquid crystal may be dispersed in the resin matrix.

In particular, it is preferable to use a photocurable or thermosetting resin as the resin to be used, since it can be cured in a closed system.Moreover, a photocurable resin is particularly preferred because it is not affected by heat and can be cured in a short time. This is preferable.

More specifically, it is preferable to use a photocurable vinyl resin, examples of which include photocurable acrylic resins, and those containing an acrylic oligomer that polymerizes and cures when exposed to light are particularly preferable.

The specific manufacturing method is to form a cell using a sealing material in the same way as a conventional normal TN type liquid crystal display element, inject a mixture of uncured liquid crystal and resin matrix through an injection port, and seal the injection port. After stopping, it can be cured by irradiation with light or by heating.

Alternatively, an uncured mixture of liquid crystal and resin matrix may be supplied onto the electrode-equipped substrate, and then another electrode-equipped substrate may be placed on top of the mixture, and the mixture may be cured by light irradiation or the like.

Additionally, ceramic particles for controlling the gap between the substrates, plastic particles, spacers such as glass fibers, pigments, dyes, viscosity modifiers, and other additives that do not adversely affect the performance of the invention may be added to this uncured mixture. good.

In the case of such elements, by applying a sufficiently high voltage only to a specific part during the curing process, that part can always be in a light-transmitting state, so it is possible to permanently display the item you want to display. In some cases, such normally transparent portions may be formed.

The response time of a liquid crystal display element using such a liquid crystal resin composite is approximately 3 to 50 m5 ec for the rise of voltage application and approximately 10 to 80 m5 ec for the fall of voltage removal, which is faster than that of conventional TN type liquid crystal display elements. , its voltage-transmittance electro-optical characteristics are also suitable for driving for gradation display.

Also, the volume fraction of operable liquid crystal in the liquid crystal resin composite Φ
is preferably Φ>20% from the viewpoint of scattering properties in the absence of an electric field,
Φ>35% is more preferable.

If Φ is too large, the structural stability of the liquid crystal resin composite will be poor, so Φ<70% is preferable.

Such a liquid crystal resin composite is used by being sandwiched between electrode-equipped substrates. A liquid crystal display element using this liquid crystal resin composite does not have good multiplex drive characteristics, so when creating a liquid crystal display element with a large number of pixels, an active element is placed in each pixel. In the case of a scattering type display element as well, active elements are arranged as necessary.

When using a three-terminal element such as a TPT (thin film transistor) as this active element, it is sufficient to provide a solid electrode common to all pixels on the other electrode-attached substrate.
When using a two-terminal element such as a diode, the other electrode-attached substrate is patterned in a stripe shape.

Furthermore, when TPT is used as the active element, silicon is suitable as the semiconductor material. In particular, polycrystalline silicon is not as photosensitive as amorphous silicon, so
When using amorphous silicon, which is preferable because it does not malfunction even if the light from the light source is not blocked by a light-shielding film, a light-shielding film is also used.

Further, the electrode is usually a transparent electrode, but when used as a reflective liquid crystal display element, it may be a reflective electrode made of chromium, aluminum, or the like.

As mentioned above, a projection type display device usually uses a transmission scattering type display element as a transmission type, and projects an image onto a separate screen. In this case, whether it is a front projection type (viewer is positioned on the side of the projection display) or a rear projection type (viewer is positioned on the opposite side of the projection display) good.

It is also possible to use a reflective liquid crystal display element that uses a reflective electrode or has a reflective layer on the back side of the element to provide a reflective projection display device that guides the emitted light to the incident side and projects it. In this case, it is preferable to subject the substrate surface to anti-reflection treatment in order to reduce reflection on the element surface.

This transmission-scattering display element can be used as a transmission-scattering display element with a solid electrode on the entire surface, as a transmission-scattering display element with simple electrode patterning, as a projection display device, or as an illumination device.

For example, by configuring the device itself as shown in FIG. 1 and embedding it in a wall, ceiling, etc., it is possible to control the light at high speed without changing the color.

In addition, the device shown in Figure 4 or Figure 5 may have such a configuration and be installed embedded in a wall, ceiling, etc. It is possible to dim the light while changing the brightness.

[Function] According to the present invention, a projection light source system using an elliptical mirror, a light source, a conical prism, and a condensing lens is used. Therefore, a large amount of light from the light source can be used with a small elliptical mirror, and the light source can be made more compact by increasing the usage efficiency of the light source.

Furthermore, by using a prism, the incident light range is widened to increase the effective light quantity, and the diameter on the 8-ray side is made small to obtain light that is closer to a point light source, that is, a more uniform luminous flux. For this reason, the constraints are more uniform than when a prism is not used and only a diaphragm with the same diameter as the prism bottom cross section is used.
Conversely, the amount of light is greater (brighter) than if only a simple aperture with the same diameter as the top surface of the prism was used.

Furthermore, since the light beams incident on the transmission-scattering display element are uniform, scattered light can be removed with high efficiency from the straight-line transmitted light that has passed through the transmission-scattering display element, and a projected image with a high contrast ratio can be obtained.

In the present invention, the prism is shaped like a cone or a pyramid, and a prism is used in which light incident on the prism is substantially totally reflected on the side surfaces of the prism. For example, in Figure 2 (B
) enters the prism at an angle θ from the optical axis and enters the bottom of the prism at an angle θ0φ (with respect to the direction perpendicular to the bottom), at an angle n-5inθ' determined by the refractive index n of the prism.
It enters the prism at an angle θ゛ that satisfies = sin(θ+φ). This light hits the side of the prism at an angle of X (X=φ
+ψ−θ°), and this X is the total reflection critical angle θc
If the value is larger than (=5in-' (1/n)), total reflection occurs on the side surface of the prism. In this way, the incident angle decreases by (1802φ) every time the light is reflected from the side surface, and when it becomes less than the critical angle θC, it is emitted from the side surface without being totally reflected.

Therefore, the inclination angle ψ of the prism side surface and the length of the prism (distance between the bottom surface and the top surface) may be determined so that no light is emitted from the prism side surface. As a result, a projection light source system with a large amount of light and uniform constraints can be obtained.
A projection display device with high brightness (and high contrast ratio) can be obtained.

In addition, by making the second aperture variable, for example, when the surroundings are dark, the influence of light from the surroundings on the screen is small (
Since it is possible to distinguish dark spots from a projection display device, the contrast ratio can be adjusted to be high even if the aperture is narrowed to reduce the amount of light, resulting in a display image with a high contrast ratio (brightness that is easy to see).

Conversely, when the surroundings are bright, light from the surroundings will be reflected on the screen, so dark spots on a projection display will not look dark, but will appear bright to some extent. By opening the screen, increasing the amount of projected light, and making the screen brighter, it will be easier to see and the contrast ratio will appear higher.

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

Example 1 A glass substrate provided with an ITO pixel electrode with polycrystalline silicon TPT provided in each pixel, and a glass substrate provided with a solid ITO electrode on the entire surface, spacers were scattered inside, and the surrounding area was used as an injection port. An empty cell was manufactured by removing the portion and sealing it with an epoxy sealant.

A photocurable resin made of acrylic monomers and acrylic oligomers and a nematic liquid crystal with positive dielectric anisotropy are mixed into this, the dissolved mixture is injected, and after the injection port is irradiated with ultraviolet rays, a liquid crystal resin composite is formed. was cured to create a transmission scattering type liquid crystal display element.

As a projection light source system, a light source (emission arc length 3 mm, 2
50W metal halide lamp), elliptical mirror (first focal position F1; 15111 m, second focal position F2 = 20
0mm, total depth H=100mrn, opening diameter D=10
5mm), prism (bottom inclination angle φ = 5°, side inclination angle ψ = 86°, bottom cross-sectional diameter 16 mm, top cross-sectional diameter 8
mm, distance between the bottom cross section and the top cross section = 57, 2 mm, the top surface is shaped like a spherical lens with a diffusing surface, and the radius of curvature =
6 mm), a convex condensing lens (focal path lif = 80 mm) placed in front of a transmission-scattering liquid crystal display element, and an aperture having the same diameter as the prism at the bottom of the prism. .

The distance between the top surface of the prism and the convex lens for focusing is 120 mm.
and the distance between the condensing convex lens and the second aperture is 240
1!1I11, and the liquid crystal display element is located between the convex convex lens for condensing light and the second aperture, and is located 20 minutes from the second aperture.
It was placed at a position of 0 mm.

Using this projection display device, a display was projected onto a 40-inch reflective screen with a screen gain of 5. At this time, the maximum brightness on the screen in a dark room (ft-L
) and contrast ratio are shown in Table 1. Additionally, a comparative example (Comparative Example 1.2) of a projection light source system using only an aperture without using a prism, and a comparative example 3 using a conventional projection light source system using a spherical mirror and a lens are also shown.

Table 1 As is clear from the results, according to the present invention, a bright display can be achieved in the same manner as when the diameter of the aperture is increased, and a high contrast ratio can be obtained in the same way as when the aperture is closed down.

Example 2 As shown in Figure 4, a dichroic mirror is used to separate the light from the light source into RGBa colors, and a liquid crystal display element similar to Example 1 is arranged for each color. A condensing lens was placed at the center, and the light was condensed and combined by a dichroic mirror, passed through a second diaphragm placed at the focal point, and projected onto a screen by a projection lens.

However, the prism has an upper surface focal length of 2 mm and an extrinsic 1
The same prism as in Example 1 was used except that a microlens array of 1 mm in diameter was provided. The lens 35 is arranged so that the top surface of the prism is at the focal position, and the dichroic mirror 41
Almost parallel light is incident on the A second light condensing lens 37 was placed immediately in front of each liquid crystal display element 36.

In addition, in order to reduce the decrease in color purity due to PS polarization,
It was preferable to use a color filter in combination with each liquid crystal display element.

As a result, the brightness and contrast ratio were the same as in Example 1, but the in-plane distribution of the amount of light was more uniform.

Example 3 A projection type display device was obtained in the same manner as in Example 2, except that the liquid crystal display element in Example 2 was changed to a liquid crystal display element with a solid electrode on the entire surface. When this projection display device was mounted on a wall, it could be used as a color lighting device.

Example 4 Three reflective liquid crystal display elements were manufactured by using one side of the electrode of the liquid crystal display element of Example 1 as a reflective electrode. In addition, in this liquid crystal display element, an antireflection film was formed on the surface of the glass substrate on the side on which the transparent electrode was formed.

Using this liquid crystal display element, as shown in FIG. A second mirror 60 is arranged, and the light reflected by the mirror is focused.
A diaphragm 53 having an opening having the same shape as the prism 54 and its bottom surface was placed at the focal point of the prism 54 . A condensing lens 55 is provided behind it, followed by a gicchroic prism 61 for RGB spectroscopy, which separates the light into three colors.The light is incident on three reflective liquid crystal display elements 56, and is reflected by the electrode surface to produce the same result again. The light was emitted to a guichroic prism 61 to synthesize three colors of light. This combined light enters the same condensing lens 55 from the opposite direction and is condensed into a second condensing lens 55 which is separated from the condensing lens by the same distance as the aperture, but at a different position in the lateral direction. The light passes through the aperture 58 of No. 2 and is projected onto the screen on the left side through the projection lens 59.

Also in this case, in order to reduce the decrease in color purity due to PS polarization, it was preferable to use a color filter in combination with each liquid crystal display element.

Example 5 A projection type display device was obtained in the same manner as in Example 4, except that the liquid crystal display element in Example 4 was changed to a liquid crystal display element with a solid electrode on the entire surface. When this projection display device was mounted on a wall, it could be used as a color lighting device.

[Effects of the Invention] In the projection type display device of the present invention, since the light emitted from the light source is collected using an elliptical mirror, the light collection efficiency is high (and a bright display is possible).

In addition, since a pnosm with a specific shape is provided at the second focal position to remove diverging light, the light that is reflected by the elliptical mirror and does not reach the second focal position because the light source has an effective length. Furthermore, it is possible to remove light that is directed toward the transmission scattering type display element without being directly reflected or passing through the second focal point position, and the contrast ratio of the projected image can be improved.

In addition, since this prism has a bottom cross section > a top cross section, a large amount of incident light is taken in from the wide bottom surface, and the output light is emitted from a small area, so the luminous flux is uniform while capturing a large amount of light, making it bright and high-quality. A projection type display device with a high contrast ratio can be obtained.

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 drawings]

FIG. 1 is a schematic diagram showing the configuration of a basic example of a projection type display device of the present invention. FIGS. 2(A), 2(B), 2(C), and 2(D) are side views illustrating the shape of a prism used in the present invention. FIG. 3 is an enlarged sectional view of the projection light source system of the present invention. FIGS. 4 and 5 are schematic diagrams showing the configuration of an example of a color projection type display device of the present invention. FIGS. 6A, 6B, and 6C are schematic diagrams showing the configuration of an example of a conventional projection display device. Light source = 1.21.31.51 elliptical mirror
: 2.22.32.51 aperture = 3.
23.33 Prism = 4, IIA, IIB, lIC1
IID, 24.34.54 Lens: 5.7.9.35.37A, 37B
, 37G, 55 Transmissive scattering display element: 6.36A, 36B, 36G
, 56A, 56B, 56G Guicroic mirror: 41.43.44.46 mirror
:42.45.60 Guikkreuzk Prism 261 Figure Figure Figure Figure Figure Figure

Claims (5)

[Claims] (1) A projection type that has a projection light source system, a transmission scattering display element into which light from the projection light source system enters, and a projection optical system that projects the light emitted from the transmission scattering display element onto a screen. The display device uses a cone-shaped prism whose bottom cross section is larger than the top cross section, and has an elliptical mirror, a light source, an aperture, and a condensing lens as a projection light source system. A light source is placed at a focal position, the light from the light source is focused at a second focal position, and only the light that has passed through the prism located at the second focal position is focused by a focusing lens. What is claimed is: 1. A projection type display device, characterized in that the light is incident on a transmission scattering type display element. (2) The projection type display device according to claim 1, further comprising a projection optical system in which a diaphragm having an opening having the same shape as the bottom surface of the prism is disposed on the bottom surface of the prism. (3) The projection display device according to claim 1 is provided with a projection optical system that collects the light emitted from the transmission scattering display element and has a second diaphragm having an aperture at its focal position. A projection display device characterized by: (4) In the projection type display device according to any one of claims 1 to 3, the transmission scattering type display element has a nematic liquid crystal having a positive dielectric anisotropy dispersed and held in a resin matrix between the electrode-attached substrates, and the resin matrix A projection type display characterized in that it is a transmission scattering type liquid crystal display element sandwiching a liquid crystal resin composite whose refractive index almost matches the ordinary refractive index (n_o) of the liquid crystal used. Device. (5) An illumination device characterized by using the projection type display device according to any one of claims 1 to 4.