JPH04113344A - Projection type display device and lighting device - Google Patents

Abstract

PURPOSE:To increase the utilization efficiency of a light source, and to reduce the size and improve the contrast ratio by converging light emitted by the light source by using an elliptic mirror, providing a stop at a 2nd focus position, and removing diverged light. CONSTITUTION:Light emitted by a light source 1 is reflected by the elliptic mirror 2, and the luminous flux is made uniform through a stop 3 and converged by a converging lens 4 into parallel light. which is passed through a transmission scatter type display element 5 and converged by a converging lens 6 ; and a 2nd stop 7 as a means for removing scattered light removes the scattered light and the light is projected on a right-side screen through a lens 8 for projection. Light emitted by a light source 11, on the other hand, is reflected by an elliptic mirror 12 and made uniform through a stop 13, and the light is converged by a converging lens 14 into luminous flux which is focused on the position of a 2nd stop 17; and the light is passed through a transmission scatter type display element 15 and the 2nd stop 17 as a means which removes scattered light removes the scattered light, so that the light is projected on the right screen through a projection lens 18.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J] 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, a projection type display device has generally used a CRT, but it has the disadvantage that the device is 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, it has a problem that there is a large loss of light (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 display element does not use a polarizing plate, it is possible to obtain a bright projected image because almost no light is lost during transmission (light is transmitted).

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.

[Problems to be Solved by the Invention] Figures 4 (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. 4(A) shows a projection light source system using a light source 41 and an elliptical mirror or a parabolic mirror 42, which allows light to enter a transmission scattering display element 45 without using a condensing lens. An example is shown below. This example had the problem of requiring a large elliptical or parabolic mirror. moreover,
A 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. This had a major problem in that the contrast ratio deteriorated, which did not occur when a TN type liquid crystal display element was used.

FIG. 4(B) shows a projection light source system using a light source 51, a spherical mirror 52, and a condensing lens 54, and the lens 54 is used to cause light to enter a transmission scattering display element 55. An example is shown below. 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. 4(C) shows a projection light source system using a light source 61, an elliptical mirror 62, and a condensing lens 64. An example is shown below. In this example, the elliptical mirror could be small, and the light from the light source was often used. but,
Similar to example (A), a portion of the light from the light source directly enters the transmission-scattering display element obliquely, and the scattered light is mixed with the original transmitted light, resulting in a decrease in contrast ratio. It had a big problem.

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. Niku (naru)

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 the TN type liquid crystal display element does not emit light to the side opposite to the light source in the OFF part, whereas the transmission random number display element emits light even in the OFF part. 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.

Therefore, 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 utilization efficiency of the light source, 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 that projects light emitted from the transmission scattering type display element onto a screen; A light source is placed at the first focal position of the elliptical mirror, the light from the light source is focused at the second focal position, and the light passing through the aperture of the diaphragm located at the second focal position is focused. a projection type display device characterized by condensing light with a lens and making it incident on a transmission scattering type display element;
The present invention also provides a lighting device using the same.

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, an aperture, and a condensing lens, so the light flux that enters the transmission scattering display element is uniform, and the The scattered light can be removed with high efficiency by the means for removing scattered light, the light source can be used more efficiently, the light source can be made smaller, and a projected image with a high contrast ratio can be obtained.

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 (n0) 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 spacer movement are less likely to occur.

Note that the transmission scattering type display element sandwiching this liquid crystal resin composite does not have good multiplex drive characteristics, so it is usually used with an active element provided in each pixel electrode for purposes other than simple Bakun display.

In addition, this liquid crystal resin composite has a resistivity equivalent to that of the conventional TN mode, and it is easy to design active elements without having to provide a large storage capacitance for each pixel electrode as in the DS mode. Moreover, the power consumption of the liquid crystal display element can be kept low.Therefore, it is possible to manufacture it by simply removing the alignment film formation process from the manufacturing process of conventional TN mode liquid crystal display elements, making production easy. It is.

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, an aperture, and a condensing lens. A light source is placed at the first focal position of the elliptical mirror, the light from the light source is focused at the second focal position, and the light passing through the aperture of the diaphragm located at the second focal position is focused. It is arranged so that the light is focused by a light lens and then incident.

Note that it is most efficient to arrange the diaphragm at the second focal position, but in some cases it may be arranged shifted back and forth in the optical axis direction. In particular, as will be described later, when the diameter of the aperture of the diaphragm is fixed and the amount of light is adjusted, the diaphragm may be made movable in the optical axis direction and adjusted.

In the present invention, since a considerable portion of the light source is covered with an elliptical mirror, the light emitted from the light source can be utilized by reflecting it.Furthermore, like a spherical mirror, most of the reflected light returns to the light source, There is less loss due to not passing the reflected light and the efficiency of light usage is improved.Furthermore, since a condensing lens is used, a small elliptical mirror can be used instead of an expensive large elliptical mirror. There is no need to use a mirror, and the projection light source system can be miniaturized.Furthermore, a diaphragm having an aperture is disposed at the second focal point of the elliptical mirror.

This eliminates light components that are misaligned in the light flux, which are more likely to occur with a spherical mirror using a finite length light source and an elliptical mirror, and light components that are not reflected and go directly to the condenser lens without passing through the second focal point, thereby aligning the light fluxes. This makes it possible to reduce unnecessary light that is emitted from the transmission scattering type 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 is provided between the transmission scattering type display element and the screen.

FIG. 1 and FIG. 2 show a projection type display device 1 of the present invention. FIG. 2 is a schematic diagram of an example showing the basic configuration of the device.

FIG. 1 shows an example in which the light incident on the transmission scattering type display element from the projection light source system is made into parallel light, and FIG. 2 shows an example in which the light is first focused at a focal point.

In the example shown in 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 flux passes through the aperture 3, is aligned, is focused by the condensing lens 4, becomes parallel light, passes through the transmission scattering type display element 5, is condensed by the condensing lens 6, and is scattered. Scattered light is removed by a second aperture 7 serving as a light removing means, and projected onto a right screen (not shown) by a projection lens 8. This light source 1, elliptical mirror 2, aperture 3,
The condensing lens 4 constitutes a projection light source system, and the condensing lens 6, the second aperture 7, and the projection lens 8 constitute a projection optical system.

In the example shown in FIG. 2, the light source 11 is placed at the first focal point of the elliptical mirror 12, and the light emitted from the light source 11 is reflected by the elliptical mirror 12, passes through the aperture 13, and the luminous flux is aligned and focused. The light is condensed by the optical lens 14 to form a light beam that is focused at the position of the second aperture 17, and is transmitted to the transmission scattering display element 15.
The scattered light is removed by a second aperture 7 serving as a means for removing scattered light, and is projected onto a screen on the right side (not shown) by a projection lens 18. This light source 11, elliptical mirror 12, aperture 13, condensing lens 1
4 constitutes a projection light source system, and a second aperture 17 and a projection lens 18 constitute a projection optical system.

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, dichroic prism, etc. is used to separate the light into three colors of RGB, and the transmitted light is controlled by a transmission scattering type display element without a color filter, and the transmitted light is combined and projected. be done.

FIG. 3 shows an example of this, and is a schematic diagram of an example using a dichroic prism.

In Fig. 3, 21 is a light source, 22 is an elliptical mirror, 23 is a diaphragm, 24 is a condensing lens, 25 is a spectroscopy guichroic prism, 26, 27, 28, 29 are mirrors, 2
1 to 29 constitute a projection light source system. 30, 31, and 32 are transmission-scattering display elements corresponding to each color, 33 is a combining gicroic prism, 34 is a condensing lens, 35 is a second aperture as a means for removing scattered light, and 36 is a A projection lens 37 is a screen for projection. 33 to 36 constitute a projection optical system.

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

The elliptical mirror may be any mirror as long as it can arrange the light source described above at its first focal position and a diaphragm described below 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 diaphragm disposed at the second focal position is for the purpose of using only the light that has been condensed at the second focal position and has a uniform luminous flux.

Specifically, an aperture with a hole as shown in the example described above, a small mirror, etc. can be used.

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 is focused by the focusing lens.

The diameter D1 of the aperture of this diaphragm may be determined by considering the size of the light source, desired brightness, contrast ratio, etc. It is also preferable that the size of the opening can be changed so that it can be adjusted.

Normally, when creating parallel light as in the example in Figure 1,
It is preferable that the ratio 0+/f+ between the diameter D1 of the aperture and the focal length fl of the condensing lens is 0.18 or less.

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 the range that does not impair the effects of the present invention. ,
Spectroscopy may also be performed using a dichroic mirror instead of the dichroic prism described above.

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, if the projection distance is not long (otherwise, the scattered light cannot be removed sufficiently and is not practical, so it is preferable to provide a means to remove the scattered light. Specifically, after passing through the transmission scattering type display element, Once the transmitted light is focused, a second diaphragm is provided at the focal point position.This second diaphragm can be an aperture with a hole similar to the diaphragm of the projection light source system described above, a small mirror, etc. 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 shown in Figure 3, the configuration may be such that they are combined using a dichroic prism or a quick click mirror before being projected, or the images may be projected individually and then combined on a screen. Since there is only one optical axis when projecting from the front, 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 combined optical path as shown in FIG. 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 display element of the present invention can be used as long as it is a flat display element that can take on a transmission state and a scattering state depending on the voltage application state.

Specifically, we use DSM (dynamic scattering mode) liquid crystal display elements, liquid crystal resins in which liquid crystals are 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 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 dielectric anisotropic or positive nematic liquid crystal is used, and the refractive index of the resin 7trix is made to almost match the ordinary refractive index (n0) of the liquid crystal used, so that when a voltage is applied, a high Because it exhibits transparency, and because the areas between pixels without electrodes are in a scattering state (turns black when projected onto a screen), the contrast of the projected image can be improved even if there is no light-shielding film between the pixels. preferable.

The 71-item resin composite, which consists of a resin 71 helix with many fine pores and liquid crystal filled in the pores, has a structure in which the liquid crystal is sealed in liquid bubbles like microcapsules. However, individual microcapsules may not be completely independent (or individual liquid crystal bubbles may communicate through slits as in a porous material).

This liquid crystal resin composite is produced by mixing the liquid crystal and the materials constituting the resins 71 to 71 to form a solution or latex, and then subjecting this to photocuring, thermal curing, curing by solvent removal, reaction curing, etc. The resin 7 matrix may be separated 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, pigments, viscosity modifiers, and other additives that do not adversely affect the performance of the present 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 becomes too large, the structural stability of the liquid crystal resin composite deteriorates, 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 a liquid crystal display element with a large number of pixels is used, an active element is arranged in each pixel. Of course, in the case of other transmission scattering type display elements, active elements are arranged as necessary.

When using a 3-terminal element such as TPT (thin film transistor) as this active element, it is sufficient to provide a solid electrode common to all pixels on the other substrate with electrodes.
When using a two-terminal element such as a diode, the other electrode-attached substrate is patterned into stripes.

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
It is preferable that the light from the light source is not blocked by the light shielding film because malfunction does not occur. When using amorphous silicon, 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 described above, a projection type display device usually uses a transmission type display element as a transmission type, and projects images onto a separately placed screen. In this case, even if it is a front projection type (viewer is positioned on the side of the projection type display), it is a rear projection type (viewer is positioned on the opposite side of the projection type display).
It may be.

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.

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 having the device shown in FIG. 1 or 2 have such a configuration and embedding it in a wall, ceiling, etc., it is possible to control the light at high speed without changing the color.

In addition, by configuring the device shown in Figure 3 and placing it embedded in a wall, ceiling, etc., it is possible to dim the light at high speed without changing the color, or to dim the light while changing the color. It can be illuminated.

[Function] According to the present invention, a projection light source system using an elliptical mirror, a light source, an aperture, 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, since the light beams incident on the transmission-scattering type display element are aligned, scattered light can be removed with high efficiency from the straight-line transmitted light that has passed through the transmission-scattering type display element, making it possible to obtain a projected image with a high contrast ratio. .

In this case, it is preferable to make the diameter of the aperture of the projection light source system and the second aperture of the projection optical system variable. However, it is also possible to make the position of the diaphragm movable in the optical axis direction as a substitute, although the effect is somewhat reduced.

With this adjustment, for example, when the surroundings are dark, the influence of light from the surroundings on the screen is small, dark spots on the projection display device can be distinguished, and the contrast ratio appears high. Another problem is that when the surroundings are dark, if the image on the screen is too bright, it can cause eye strain. Therefore, even if the overall brightness is slightly lower, it is easier to see by increasing the contrast ratio between bright and dark points.
It is preferable to narrow down at least one of the two apertures to reduce the amount of projected light, but to improve the removal rate of scattered light.

Conversely, when the surroundings are bright, light from the surroundings will be reflected on the screen, so the dark spots caused by the projection display device will be dark (invisible) and will appear bright to some extent.For this reason, the projection display device itself Even if the contrast ratio of the projected image is high, the apparent contrast ratio on the screen will be significantly reduced.In this case, open at least one of the two apertures mentioned above to increase the amount of projected light. By making the screen brighter, it is easier to see (the contrast ratio appears 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 vector 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 (light emitting filament length 5 mm
, 250W metal halide lamp), elliptical mirror (first focal position F1 = 15 mm, second focal position F2 = 85 m
m, total depth H = 40mm, opening diameter D = 70mm)
, a convex lens for focusing light (focus, distance f: 80 mm) and a diaphragm (aperture) were used. As shown in Figure 2, a light source was placed at the first focal position of the elliptical mirror, an aperture was placed at the second focal position, and a convex lens for condensing light was placed at a distance of 120 mm from the aperture. .

A transmission scattering type liquid crystal display element was placed at a position 40 mm from the convex condensing lens, and a second diaphragm was placed at a position further 240 mm away.

Using this projection display device, a display was projected onto a 40-inch reflective screen with a screen gain of 5. Aperture diameter of the aperture, (mm), second aperture aperture diameter D2 (mm)
), the brightness on the screen (maximum brightness and minimum brightness: ft-L), the contrast ratio in a dark room, and the contrast ratio in a bright room are shown in Table 1. At the same time, a comparative example in which the projection light source system is not provided with an aperture is also shown.

In addition, when the screen brightness was measured in a bright room, it was about 8 ft-L.

Table 1 Therefore, according to the embodiment of the present invention, an image with a contrast ratio of 100 or more and a maximum of 300 can be obtained by reducing the aperture diameter in a dark room, and even in a bright room by increasing the aperture diameter. By doing so, a contrast ratio of about 30 was obtained. Furthermore, in the case of high brightness, the brightness was about 5 times greater than in the case of the configuration shown in FIG. 4(B) using a conventional spherical mirror.

On the other hand, in a comparative example in which no aperture is provided in the projection light source system,
A much lower contrast ratio was obtained.

Example 2 Using a guichroic mirror to convert light from a light source into RGB
A color is separated, a liquid crystal display element similar to that in Example 1 is placed for each color, and a condensing lens is placed behind the liquid crystal display element to condense the light and combine it with a gicroic mirror. Then, the image was projected onto a screen by a projection lens through a second diaphragm placed at the focal point.

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.

This result was similar to Example 1.

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, the same elliptical mirror, light source, aperture, and condensing lens as in Example 1 were used, and a mirror tilted slightly from 45° was placed just before the second focal point of the elliptical mirror. , an aperture is placed at the second focal position where the light reflected by the mirror is focused. A dichroic prism for RGB spectroscopy is installed behind it to separate the light into three colors, which is then incident on three reflective liquid crystal display elements, reflected by the electrode surface, and emitted to the same dichroic prism again to synthesize the three colors of light. did. This combined light enters the same condensing lens from the opposite direction, and is condensed into a second condensing lens 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 diaphragm and is projected onto the screen through a projection lens.

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 display device of the present invention, the light emitted from the light source is collected using an elliptical mirror, so that the light collection efficiency is high and a bright display is possible.

In addition, since an aperture is provided at the second focal position to remove divergent light, the light source has an effective length and is reflected by the elliptical mirror and does not reach the second focal position, as well as direct reflection. The contrast ratio of the projected image can be improved because the light directed toward the transmission-scattering display element can be removed without passing through the second focal point.

In addition, by making at least one of the aperture and the second aperture variable, the amount of transmitted light and the removal efficiency of scattered light can be varied, so the brightness and contrast of the image can be adjusted according to the brightness of the room. Increase the amount of transmitted light, improve the maximum brightness, and increase the amount of scattered light (although this will also cover the contrast ratio to some extent.On the other hand, in a dark room, even if you sacrifice the maximum brightness, you can increase the maximum brightness). It widens the difference in maximum brightness and improves the contrast ratio. This makes it possible to use it in bright rooms and places where the brightness of the room changes, which was previously impossible.

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

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are schematic diagrams showing the configuration of a basic example of a projection type display device of the present invention. FIG. 3 is a schematic diagram showing the configuration of an example of a color projection type display device of the present invention. FIGS. 4(A), 4(B), and 4(C) are schematic diagrams showing the configuration of an example of a conventional projection type display device. Light source: 1, 1]. , 21, 41, 5],
6] Elliptical mirror ・2, 12, 22, 6j aperture
: 3, 7, 13, 17, 23, 35 lens 4, 6, 8, 14, 18, 24, 34
, 36, 54, 64 transmission scattering display element = 5, 15, 30, 31, 324
5, 55, 65 Guicroic prism: 25, 33 Mirror: 26, 27, 28, 29 Projection screen, 37 Elliptical or parabolic mirror: 42 (A) (B) (C) Fig.

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 has an elliptical mirror, a light source, an aperture, and a condensing lens as a projection light source system, and a first
A light source is placed at a focal position, the light from the light source is focused at a second focal position, and the light passing through the aperture of the diaphragm located at the second focal position is focused by a focusing lens. A projection type display device characterized in that light is incident on a transmission scattering type display element. (2) 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 opening at its focal position. A projection display device characterized by: (3) The projection type display device according to claim 2, wherein at least one aperture is variable. (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_0) 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.