JP3355763B2 - Projection display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display device,
The present invention relates to an apparatus that can switch between two types of projection systems, a front projection system and a rear projection system.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a configuration diagram of a conventional projection display device disclosed in Japanese Patent Application Laid-Open Publication No. HEI 9-125, in which (a) shows a rear projection system and (b) shows a front projection system. In the figure, 17 is an attache case,
18 is a projection unit, 19 is a projection lens, 20 and 2
0 'is a reflection mirror, 21 is a screen support arm, 22
Is a liquid crystal screen, and 23 is a reflection screen.

The operation will be described first. As the liquid crystal screen 22, a dynamic scattering type liquid crystal plate that can be switched between an opaque state (a scattered transmission state like a ground glass) and a transparent state (a state like a transparent window glass) according to an applied voltage is used. The liquid crystal screen 22 has transparent electrodes provided inside two glass substrates facing each other, and further has an SiO ₂ film provided inside the transparent electrodes, and a liquid crystal layer is formed between the SiO ₂ films. . When an AC power supply is connected to the transparent electrode via a switch to apply a voltage to the transparent electrode, and the switch is connected to cause a predetermined current to flow, the liquid crystal screen 22 becomes a scattering plate depending on the state of the liquid crystal. When the switch is turned off and the application of the current is stopped, the liquid crystal screen
2 is a transparent plate. In the state of the scattering plate, it becomes rear projection,
In the state of the transparent plate, front projection is performed by projecting onto a reflection screen arranged at a predetermined distance from the projection device.

In the projection device, components other than the reflection screen 23 are contained in an attache case 17, and except for projection, the liquid crystal screen 22, the screen support arm 21, and the second reflection mirror 20 'are contained therein. When the upper lid is closed in the closed state, each part is stored in the attache case 17, and the state becomes convenient for carrying.

[0005]

The above description has been made with reference to FIG. 14 on a conventional rear projection apparatus which can switch between two types of projection methods, front projection and rear projection. A single device can easily switch between the rear projection optical path and the front projection optical path, so that the user can use both types according to the situation. In addition, since a projector is commonly used as compared with a conventional rear type or front type device which is installed one by one, the installation space can be reduced and the cost required for introducing the device can be reduced. Can be. Further, since the apparatus body is housed inside the attache case, it is convenient to carry. However, the conventional method has the following problems.

(1) In the advanced video information society in recent years, there is a strong demand for a portable information display device that is very small, lightweight, excellent in portability, and provides a large-screen display when used. This can be said to be common to both business use and personal use fields, and it is important to have functions that can be used for both individual use and multi-person use. It is becoming. In the conventional example of the above-described projection display device, when the device body is stored inside the attache case, it cannot be said that the device is sufficiently excellent in portability and portability, and when considering use on an actual desk, etc. It is hard to say that it is excellent in terms of space saving.

(2) It is also possible to reduce the size and weight of the main body of the device, and to provide high brightness corresponding to a large screen, power saving / long life corresponding to portability, and excellent natural color reproduction. And does not provide a light source device that achieves high color rendering properties. Further, it does not show the configuration of the projection optical system that allows the device main body to be downsized.

(3) When a screen made of a dynamic scattering liquid crystal is used and switching between transparent and opaque is performed depending on the voltage application state to select front projection or rear projection, the scattering of the screen for rear projection, which is a main application. Since the state is realized by passing a current, an increase in power consumption is inevitable.

(4) Further, not only the screen made of the scattering mode liquid crystal alone deteriorates the contrast, but also no effective device is provided for preventing a significant decrease in the contrast particularly when the screen is used in a bright room. .

(5) Even if the light distribution characteristics of the screen are changed by the voltage applied to the scattering mode liquid crystal screen to obtain a wide viewing angle, it is impossible to obtain a high screen gain at the same time. there were.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a small, lightweight, portable, storage-friendly and space-saving when used, high brightness, It is an object of the present invention to provide a projection display device capable of switching between two types of projection, front projection and rear projection, which enables high contrast, power saving, and natural color reproduction.

[0012]

According to a first aspect of the present invention, there is provided a projection type display apparatus comprising: an image forming means;
An illumination optical system for illuminating the step;
Projection lens means for enlarging and projecting the projected image, and the projection lens
Mirror that bends and guides the optical path of the projected light emitted from the
And the projection light guided by the mirror means is incident.
Rear screen means for forming an enlarged image by
Image forming means, illumination optical system, projection lens means, mirror means
Opening and closing the rear screen
Screen holding means that can be freely supported.
Projection type that can switch between rear projection and front projection
In the display device, the screen holding means is closed.
In this state, the rear screen is stored inside the cabinet.
The rear screen means is scattered by applying a voltage.
Mode that allows continuous selection of
A liquid crystal screen.
Switching at a cycle faster than the temporal resolution of the eye
Features that can be controlled Der Rukoto screen gain and viewing angle Ri is
Sign.

According to a second aspect, the image forming means includes:
An illumination optical system for illuminating an image forming unit;
Projection lens means for enlarging and projecting the image formed on the step;
Bending the optical path of the projection light emitted from the projection lens means
Mirror means for guiding the light, and projection means guided by the mirror means.
Rear screen means for forming a magnified image by receiving light
And the image forming unit, an illumination optical system, a projection lens unit,
Cabinet means with built-in mirror means and rear screen
Holding the screen so that it can open and close freely
Means to switch between rear projection and front projection.
The projection holding display means,
When the rear screen is closed,
And the rear screen means is adapted to apply a voltage.
More scattering state and transmission state can be selected continuously
Liquid crystal screen, and the liquid crystal screen
The polymer part is composed of multiple layers of polymer dispersed liquid crystal.
And each layer can be driven independently.
I do.

According to a third aspect of the present invention, the image forming means includes:
An illumination optical system for illuminating an image forming unit;
Projection lens means for enlarging and projecting the image formed on the step,
Bending the optical path of the projection light emitted from the projection lens means
Mirror means for guiding the light, and projection means guided by the mirror means.
Rear screen means for forming a magnified image by receiving light
And the image forming unit, an illumination optical system, a projection lens unit,
Cabinet means with built-in mirror means and rear screen
Holding the screen so that it can open and close freely
Means to switch between rear projection and front projection.
The rear screen means.
Transparent and opaque parts in one direction in the plane
The opaque part is dichroic dyed
Made of guest-host type liquid crystal mixed with
Light-shielding sheet means that can optionally adjust the light-shielding effect by adding
It is characterized by having.

According to a fourth aspect of the present invention, the image forming means includes:
An illumination optical system for illuminating an image forming unit;
Projection lens means for enlarging and projecting the image formed on the step,
Bending the optical path of the projection light emitted from the projection lens means
Mirror means for guiding the light, and projection means guided by the mirror means.
Rear screen means for forming a magnified image by receiving light
And the image forming unit, an illumination optical system, a projection lens unit,
Cabinet means with built-in mirror means and rear screen
Holding the screen so that it can open and close freely
Means to switch between rear projection and front projection.
In a functional projection type display device, the mirror means is used for rear projection.
Left / right inversion of image according to switching between projection and front projection
It has a function.

According to a fifth aspect of the present invention, the mirror means is small.
Hold at least two mirrors and mirror means
The holder means and the support,
Part of the support is movable, and the state of the flat mirror and the left
It is characterized in that both states of the right mirror can be configured.
You.

According to a sixth aspect of the present invention, the mirror means includes:
During rear projection, the angle between the two mirrors is 180 degrees
Left and right mirrors, and
Is a flat mirror in which the angle between the two mirrors is 90 degrees
It is characterized by being in the state of-.

According to a seventh aspect of the present invention , the light of the illumination optical system is
The source is characterized by a gas discharge bulb.

[0019]

According to the projection type display apparatus of the present invention, in the first aspect, the main body can be housed in the same cabinet as a notebook type personal computer, and the cabinet which holds the rear screen means. The rear screen means can be housed inside the cabinet means when not in use by a part of the turning operation, so that a very large rear screen means can be obtained as compared with the size of the main unit.

Further, by using a scattering mode liquid crystal as a part of the screen means, it is possible not only to easily switch between front projection and rear projection, but also to apply voltage and make no mark.
Switching at a cycle faster than the temporal resolution of the eye
Accordingly, the light distribution characteristics and the screen gain can be easily controlled.

According to a second aspect of the present invention, the liquid crystal screen portion is formed of a plurality of layers, and the liquid crystal screen portion is made of a polymer dispersed liquid crystal which can be driven independently of each layer, and each layer is driven independently. Thus, the light distribution characteristics and the screen gain can be effectively controlled.

In the third aspect , the light-shielding effect can be easily adjusted by using a light-shielding substance made of a guest-host type liquid crystal mixed with a dichroic dye.

According to the fourth aspect of the present invention, according to the mirror means comprising two flat mirrors formed at an angle of 90 degrees with each other, the image forming means does not need to perform an electrical left-right reversal operation. When switching between projection / front projection, normal images can be obtained in the upper, lower, left and right directions.

According to a fifth aspect of the present invention, in a left-right reversing mirror constituted by two flat mirrors which can change the angle formed therebetween, when the angle formed between the mirrors is 90 degrees, the left and right of the projected image are inverted. , 180 degrees, the left and right sides of the projected image are not inverted.

Further, in claim 6, the angles formed by each other
Left-right reversal composed of two flat mirrors with variable degrees
When the angle between the mirrors is 90 degrees,
Indicates that the left and right sides of the projected image are reversed,
Does not reverse the left and right of the projected image.

Further, in claim 7, the gas discharge valve used in the light source of the illumination optical system, a high efficiency, it is possible to perform illumination high color temperature, also allows long continuous use.

[0027]

[Embodiment 1] FIG. 1 is a diagram illustrating a configuration of a projection display apparatus according to a first embodiment of the present invention. In the figure, 1 is a reflector, 2 is a light source, 3 is a condenser lens, 4 is a holder, 5 is a projection lens,
6, 6 'are flat mirrors, 7 is projection light, 8 is a cabinet, and 9 is a rear screen.

First, the operation of the first embodiment will be described.
Illumination light emitted from the light source 2 is condensed by the reflector 1 and the condenser lens 3 and enters the holder 4. A light valve or a positive film is mounted on the holder 4, and light incident on the holder 4 is modulated by the light valve or the positive film, and subsequently incident on the projection lens 5. The projection light 7 emitted from the projection lens 5 is bent inside the cabinet 8 by the flat mirrors 6 and 6 ′,
The image is projected on the rear screen 9 to form an enlarged image, and is used for viewing as a rear projection method.

FIG. 2 is a structural view showing the storage of the rear screen of the projection type display apparatus according to the first embodiment of the present invention. In other words, the cabinet 8 is partially closed to store the rear screen 9 so as to be portable. Shows where it has become.
The components in FIG. 2 are the same as those in FIG. When a part of the cabinet 8 is closed as shown in FIG. 2, the rear screen 9 is housed inside the cabinet 8, and has a compact form excellent in carrying, installing and storing.

FIG. 3 is a diagram for explaining the operation of the screen holding unit of the projection display device according to the first embodiment. In the figure, 8 'is a part of the cabinet, 10 is a rotation center of the part 8' of the cabinet, 11 is a screen holding part, 1
2 is a guide. A part 8 ′ of the cabinet can rotate around a rotation center 10, and the rear screen 9 can be easily moved inside the cabinet 8 by sliding the screen holding unit 11 along the guide 12 as shown in FIG. Can be stored. Similarly, it is possible to easily start up the screen holding unit 11 from the storage state to the use state.

In the present invention, the light source uses a gas discharge bulb (xen arc lamp; OSRAM GmbH, catalog) of D1 as an international standard (ECE-Reg) for a vehicle-mounted headlamp. The D1 lamp is approximately four times as efficient as the halogen lamp, which is widely used in conventional small-sized liquid crystal projectors. Are suitable. And a lifespan of 1500
It is much longer than the time and the halogen lamp, and the lamp replacement cycle can be lengthened. Further, since the shape of the lamp is small, it is suitable for miniaturization of the main body device, and it is easy to make it unitary with the reflector to improve the simplicity at the time of replacement. Furthermore, the color temperature is 4500K, which is higher than that of a halogen lamp (about 3000K), and is suitable for natural color reproduction.

In this embodiment, the reflector 1 and the condenser lens 3 are used as a method for condensing the light beam emitted from the light source 2. As a modification, for example, only a reflector such as a parabolic mirror or an elliptical mirror is used. Alternatively, another optical component may be added to improve the light collecting performance. The light source 2 is not limited to the D1 bulb, and has features of high luminance, power saving, long life, and high color rendering, and realizes a small and lightweight projection display device. If so, it is of course possible to use this.

FIG. 4 is an explanatory view of Embodiment 1 of the present invention.
(A) shows the cross section of the rear screen portion, and (b) shows the voltage / transmittance characteristics of the scattering mode liquid crystal. 4A, reference numeral 7 denotes projection light, 91 denotes a Fresnel lens, 92 denotes a scattering mode liquid crystal screen, and 93 denotes an external light removing sheet. The projection light 7 emitted from the projection lens is a Fresnel lens 91
Thereby, it is made substantially parallel to the optical axis. Next, the light is scattered by the scattering mode liquid crystal screen 92, and the final viewing angle in the horizontal direction and the screen gain are determined by the light distribution characteristics of the scattering mode liquid crystal screen 92. Further, the contrast is improved by the external light removing sheet 93.

First, the operation of the scattering mode liquid crystal screen will be described. The rear screen of the projection display device is
Normally, if the screen gain is high, the viewing angle becomes narrow, and if the viewing angle is increased, a high screen gain cannot be obtained. Since the screen does not have the function of an amplifier, the trade-off between the screen gain and the viewing angle always exists according to the law of conservation of energy.

The scattering mode liquid crystal has a voltage / transmittance characteristic as shown in FIG. As the applied voltage increases, the transmittance increases. In this state, the light distribution characteristics show that the screen gain increases, and the scattering angle decreases (near A in the figure). On the other hand, when the applied voltage is small, the scattering effect becomes large, and the point where the widest viewing angle is realized exists around B in the figure.

Therefore, the following measures are taken. 5A and 5B are explanatory diagrams of Embodiment 1 of the present invention. FIG. 5A shows a liquid crystal screen driving voltage waveform, and FIG. 5B shows a light distribution characteristic of the liquid crystal screen. The voltage waveform shown in FIG. Apply to liquid crystal screen. In FIG. 5A, when the voltage waveform in the region A is applied, a light distribution characteristic like A ′ in FIG. 5B, that is, a high screen gain is obtained, and when the voltage waveform in the region B is applied, A light distribution characteristic like B ′ in FIG. 5B, that is, a wide viewing angle is obtained. When a periodic waveform as shown in FIG. 5A is applied with a period sufficiently faster than the time resolution of the observer's eyes, it seems that a high screen gain and a wide viewing angle are obtained at the same time.

Depending on the application, it is not always necessary to obtain a high screen gain and a wide viewing angle at the same time. For personal use, for example, there is a demand that the viewing angle may be narrow but a high screen gain is required. May come. In such a case, a voltage waveform as shown in A of FIG. 5A may be continuously applied. In the present embodiment, on the contrary, a state where no voltage is applied as shown in B of FIG. Maximizing the corner can also be done easily. That is, the light distribution characteristics of the screen can be changed by arbitrarily setting the ratio of A: B.

FIG. 15 is an explanatory view of the operation principle of the scattering mode liquid crystal, and illustrates the operation principle of the polymer dispersion type liquid crystal panel which is an example of the scattering mode liquid crystal used as the rear screen in the first embodiment. ing. In FIG. 15a,
921 and 921 ′ are transparent substrates, 922 and 922 ′ are transparent conductive films, 923 is a liquid crystal droplet, 924 is a polymer matrix, 925 is an AC power supply, 926 is a switch, 927 is incident light, and 928 is transmitted light. FIG. 15B is the same as FIG.

A liquid crystal in the form of water droplets is dispersed in a polymer,
The principle of light scattering utilizes the property that the refractive index differs in the direction in which the liquid crystal is oriented. FIG. 15a shows a state in which no voltage is applied, and each droplet-like liquid crystal is oriented in an irregular direction. In this state, a difference occurs in the refractive index between the liquid crystal droplet 923 and the polymer 924, and the incident light 927 is scattered.

On the other hand, when the switch 926 is turned on and a voltage is applied, the alignment directions of the liquid crystal 923 are aligned. When the refractive index when the liquid crystal droplet 923 is oriented in a certain direction is previously matched with the refractive index of the polymer 924 as shown in FIG. 15B, the incident light 927 is transmitted without being scattered. Generally, increasing the applied voltage improves the transparency, so that the incident light 927 can be transmitted by applying a voltage equal to or higher than a predetermined value.

The polymer-dispersed liquid crystal (
For PDLC (Polymer Dispersed Liquid Crystal), for example, (JWDoane, et al .; Applied Physics)
Letters, Vol. 48, No. 4 (1981), pp. 269-271).

It should be noted that the rear screen does not necessarily have to have the configuration of the present embodiment, and a plurality of liquid crystal screens can be used in an overlapping manner in order to increase the scattering effect of the liquid crystal screen. FIG. 6 is a diagram showing the results of measuring the light distribution when three layers of a polymer dispersion type liquid crystal screen are stacked, and a voltage is applied to one or two of the layers. That is, in the figure, all three layers are in the scattered transmission state, in the figure A, two layers are in the scattered transmission state, and one layer is in the transparent state, in the figure B, one layer is in the scattered transmission state, and two layers are in the transparent state. This is C in the figure.

When the number of the scattering and transmitting layers is one, the half-value angle (the angle at which the peak intensity becomes half) is 17.5 degrees, whereas in the case of the three layers, the viewing angle is 41.3 degrees, which is twice or more. You can get the corner. In this way, if each layer is independently driven, a state intermediate between the respective states can be realized, and a very wide range of control of the light distribution characteristics can be achieved.

The rear projection system, unlike the front projection system, has the advantage that it can be viewed even in a bright room. However, reflection of external light such as illumination light on the screen deteriorates the contrast of the image on the screen. It has become. Further, as one method of improving the contrast in a bright room state, it is conceivable to suppress an increase in the luminance level of black due to external light.

Therefore, in this embodiment, a light-shielding sheet for removing external light is attached to the surface of the screen, and external light incident on the screen from above and below at an angle equal to or greater than a predetermined value is removed, so that light is removed. Contrast degradation during use in a room is significantly reduced. 7A and 7B show a light shielding sheet according to the first embodiment of the present invention, wherein FIG.
(B) is a sectional view thereof. In the figure, 91 is a Fresnel lens, 92 is a scattering mode liquid crystal screen, 93 is a light shielding sheet, 931 is a light shielding substance, 932 is a transparent medium, 93
3 is external light, 934 is light emitted from the scattering mode liquid crystal screen, and 935 is an eye.

As shown in FIG. 7B, a plate 932 having a width x made of a transparent medium such as a resin forms a laminated structure, and a light-shielding material 931 that is sufficiently thinner than x is sandwiched between adjacent plates. The light shielding sheet 93 is formed as a whole. Light 934 from the scattering mode liquid crystal screen passes through this transparent medium 932 and exits inside the vertical viewing angle θ.

The light-shielding substance 931 has a transparent or opaque black color. For example, the transparent medium 932 may be colored with a paint to shield light. When the external light 933 is incident at a certain angle or more with respect to the normal line of the light shielding sheet 93, the light shielding substance 931
Will be absorbed by In this way, the amount of external light 933 reaching the screen body can be reduced, and an increase in the black luminance level can be suppressed.

The structure of the light-shielding sheet 93 described above is very effective when the main purpose is to remove external light incident from above the screen. In this case, the vertical viewing angle θ is given by the following equation. θ = 2 sin ^-1 ｛nx / √ (x ² +
d ² ) where n is the refractive index of the transparent medium 932 and d is the thickness of the light shielding sheet 93. The vertical viewing angle θ increases as the thickness d of the light-shielding sheet 93 decreases and the width x of the transparent medium 932 increases. In this case, the effect of blocking external light decreases. It is necessary to determine an appropriate value from both the observation situation and the external light situation.

The light-shielding material 931 is not necessarily required to be transparent or opaque black, but may be colored other than black. As a modification, it is also possible to use a guest-host type liquid crystal mixed with dichroic molecules as a light-blocking substance, and adjust the degree of light absorption by applying a voltage to control the contrast. Further, depending on the situation of external light, an angle between each plane on which the light shielding material 931 is formed and the surface of the light shielding sheet 93 may be other than a right angle.

Further, the light-shielding material 931 may be a plate-like material. In this case, the light-shielding material 931 ′ and the transparent medium 932 may be alternately stacked. FIG. 8 is a perspective view illustrating a manufacturing process of the light shielding sheet 93 according to the first embodiment of the present invention. That is, as shown in FIG.
A base material 937 in which plates of 1 'and a transparent medium 932 (acrylic or the like) are alternately stacked and fixed with an adhesive 936 or the like between the layers.
The light-shielding sheet 93 can be mass-produced inexpensively by cutting a large number from the direction orthogonal to the layer as shown in FIG. 8B.

The above is an example of the configuration based on the rear projection system. However, if it is desired to immediately switch to the front projection system, the rear screen 9 is constituted only by the liquid crystal screen 92 without using the Fresnel lens 91. There is a need.
However, the light-shielding sheet 93 for improving the contrast is easily detachable, and is removed when switching to the front projection method.
Can be easily removed.

If the rear screen 9 is removed when switching from the rear projection system to the front projection system, a diffuser plate (not shown) such as a ground glass can be used as the rear screen. In this case, it is of course possible to form the rear screen 9 by combining the ground glass with the liquid crystal screen 92.

Furthermore, in this embodiment, a single-focus wide-angle projection lens is used for the projection lens 5, and a large screen can be realized with a short projection distance. Further, it is easy to reduce the size of the apparatus main body. As a modification, a zoom-type projection lens may be used so that the screen size of the enlarged image at the time of front projection can be easily changed. Further, the projection lens may have an auto-focus mechanism.

As a device for reducing the size of the apparatus body,
For example, a reflection mirror for bending the optical axis may be inserted between the holder and the projection lens as shown in FIG. 9 to reduce the area occupied by the optical components. According to the configuration of FIG. 9, the depth D can be made particularly small. In FIG. 9, 1 is a reflector, 2 is a light source, 3 is a condenser lens, 4 is a holder, 5
Is a projection lens, 6 is a flat mirror, 8 is a cabinet, 9
Denotes a rear screen, 11 denotes a screen holding unit, and 13 denotes a reflection mirror.

Further, FIGS. 10A and 10B show the configuration of the projection type display device according to the first embodiment of the present invention, wherein FIG. 10A is a perspective view thereof, and FIG. As shown in FIGS. 10A and 10B, the number of components may be reduced by using a projection lens 14 having a built-in optical axis bending mirror. 10a, b, 13 ', 1
Reference numeral 3 "denotes a bending mirror. The other components are the same as those shown in FIG. 9 and the description thereof is omitted. In the case of FIG. 10a, the first light beam that rises in the vertical direction from the horizontal direction emitted from the projection lens 14 is used. 10b, and the optical axis is bent by approximately 90 degrees by the projection mirror 14 with a built-in bending mirror, thereby realizing an arrangement of an optical system that allows the entire apparatus to be downsized.
In the case of (1), the number of components can be further reduced by making the reflection mirror incorporated in the projection lens common to the first flat mirror 6.

Embodiment 2 FIG. FIG. 11 is a diagram illustrating a configuration of a projection display apparatus according to the second embodiment of the present invention. In the figure, 1 is a reflector, 2 is a light source, 3 is a condenser lens, 4 is a holder, 5 is a projection lens, 6 is a flat mirror, 7 is projection light, 8 is a cabinet, 9 is a rear screen, 15 is a front screen, Reference numeral 16 denotes a left-right reversing mirror. The operation principle of the rear screen 9 is the same as that of the first embodiment, and the description is omitted.

First, the operation of the second embodiment will be described.
Illumination light emitted from the light source 2 is condensed by the condenser lens 3 and enters the holder 4. A light valve or a positive film is mounted on the holder 4, and light incident on the holder is modulated by the light valve or the positive film, and subsequently enters the projection lens 5. The projection light 7 emitted from the projection lens 5 is bent inside the cabinet 8 by the left-right mirror 16. In the present embodiment, a voltage is applied to the scattering mode liquid crystal screen constituting the rear screen 9 to be in a transparent state.
The projection light 7 bent at 4 passes through the rear screen 9 and is then projected on a front screen 15 installed at a predetermined distance to form an enlarged image, which is provided for viewing as a front projection system. Also, in the case of the present embodiment, a part of the cabinet 8 can be rotated similarly to the first embodiment, and the rear screen 9 can be easily stored in the cabinet 8.

Next, a description will be given of a left-right reversal mechanism of an image when switching from rear projection to front projection. When an optical system is designed on the basis of rear projection, a normal image cannot be obtained at the time of front projection unless the left and right sides of a display device that forms an image are inverted. FIG. 12 is a perspective view showing a main part of a projection display apparatus according to Embodiment 2 of the present invention, and FIG. 13 is a side view of a left-right reversing mirror according to Embodiment 2 of the present invention. 12 and 13, reference numeral 16 denotes a left-right reversing mirror, 160 denotes a flat mirror, 161 denotes a mirror holder, 162, 162 ', and 162 "support columns, and 163 a sub base. In this embodiment, as shown in FIGS. A left-right reversing mirror 16 having a left-right reversing function of a projected image is constituted by at least two flat mirrors.
At the time of front projection, the angle between the flat mirrors is 90 degrees as shown in FIG. 12A, and the left and right sides of the image are reversed. Further, at the time of rear projection, it is configured to be at 180 degrees as shown in FIG. 12B, which is the same state as a normal flat mirror.

Next, the operation of the mirror 16 will be described. FIG. 12A shows a state in which the image is horizontally inverted, but the angle between the two flat mirrors 160 is 90 degrees.
Support 16 via the mirror holder 161
2, 162 ', 162 ". Each column has its lower end fixed to the sub-base 163. The columns 162 and 162" have fulcrums at their upper ends for rotating the mirror holder 161. Each length is determined by an angle at which the light beam from the projection lens is bent to the second mirror. The support 162 "has a node near the center that bends the entire support, and the length of the support 162 'is determined so that the angle between the two flat mirrors 160 is 90 degrees when the support is straightened. Is bent, the two flat mirrors 160 begin to open around a rotation axis connecting a rotation fulcrum located at the upper end of the columns 162 and 162 ″ in a straight line, and stop when the angle between them becomes 180 degrees.
It works as a normal flat mirror that is fixed and does not flip horizontally.

When the image display device is a positive film, correct right and left magnified images can be obtained simply by reversing the front and back of the positive film when switching from rear projection to front projection, but it takes time and effort. In addition, when the image display device is a light valve, for example, in the case of a liquid crystal panel, electric circuit processing is required so that the left and right are reversed, and it is inevitable that the apparatus becomes expensive. In the present embodiment, one of the flat mirrors inside the cabinet can be used as the left-right reversing mirror, so that it is possible to provide a method that is inexpensive and does not require the trouble of left-right reversal.

[0061]

Since the present invention is configured as described above, it has the following effects.

According to the first aspect, the screen holding means which can be housed in the cabinet means holds the rear screen means made of the scattering mode liquid crystal capable of continuously selecting the scattering state and the transmission state by applying a voltage, For this reason, it is excellent in portability, installation and storage, and can be applied and applied with no voltage.
It is possible to provide a projection display device capable of switching between rear projection and front projection, in which the screen gain and the viewing angle can be controlled by switching at a cycle faster than the time resolution of the eyes .

According to the second aspect, by using polymer dispersed liquid crystal for the liquid crystal screen portion of the rear screen means, a scattering state can be realized without applying a voltage. When used mainly, a projection display device can be configured with low power consumption, and a screen gain and a viewing angle can be effectively controlled.
According to the second aspect , the polymer-dispersed liquid crystal has a multilayer structure and can be driven independently of each other, so that the light distribution characteristics and the screen gain can be more effectively controlled.

According to the third aspect , the light-shielding material made of a guest-host type liquid crystal mixed with a dichroic dye facilitates the adjustment of the light-shielding effect and reliably copes with a rapidly changing specification environment. be able to.

According to the fourth aspect of the present invention, the left-right reversing mirror facilitates normal upper, lower, left and right images at the time of switching between rear projection and front projection without performing the electrical left-right reversal operation of the image forming means. Can be obtained. Further, since a simple mechanism is used, the left-right reversal function can be obtained at low cost.

According to the fifth aspect , the left-right mirrors can change the angle formed by each other, and are 90 degrees and 1 degree.
An 80 degree state can be easily configured. For this reason, when switching between rear projection / front projection, a normal image in the upper, lower, left and right directions can be obtained immediately.

According to the sixth aspect , the left-right mirrors can change the angle formed by each other.
An 80 degree state can be easily configured. For this reason, when switching between rear projection / front projection, a normal image in the upper, lower, left and right directions can be obtained immediately.

According to the seventh aspect , the gas discharge bulb used as the light source of the illumination optical system has the characteristics of high efficiency, high color temperature, and long life, and is an international standard product. It can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a projection display apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a state in which a rear screen is stored in the projection display device according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of an operation of a screen holding unit according to the first embodiment of the present invention.

FIGS. 4A and 4B are explanatory diagrams of Example 1 of the present invention, in which a is a cross section of a rear screen, and b is a voltage / transmittance characteristic of a scattering mode liquid crystal.

FIGS. 5A and 5B are explanatory diagrams of Example 1 of the present invention, wherein a indicates a liquid crystal screen driving voltage waveform, and b indicates the light distribution characteristics of the liquid crystal screen.

FIG. 6 is a diagram illustrating light distribution characteristics of a scattering mode liquid crystal in a multilayer configuration in Example 1 of the present invention.

FIGS. 7A and 7B show the configuration of a light-shielding sheet according to the first embodiment of the present invention, where a is a perspective view and b is a cross-sectional view thereof.

FIG. 8 is a perspective view illustrating a manufacturing process of the light-shielding sheet according to the first embodiment of the present invention.

FIG. 9 is a perspective view illustrating a configuration of a projection display apparatus according to the first embodiment of the present invention.

FIGS. 10A and 10B show a configuration of a projection display apparatus according to the first embodiment of the present invention, where a is a perspective view and b is a cross-sectional view.

FIG. 11 is a diagram illustrating a configuration of a projection display apparatus according to a second embodiment of the present invention.

FIG. 12 is a perspective view showing a main part of a second embodiment of the present invention.

FIG. 13 is a side view of a left-right reversing mirror according to a second embodiment of the present invention.

FIG. 14 is a configuration diagram of a conventional projection display device, wherein a indicates a rear projection system, and b indicates a front projection system.

FIG. 15 is an explanatory diagram of the operation principle of the scattering mode liquid crystal.

[Explanation of symbols]

 8 'Part of cabinet means 11 Rear screen holding means 12 Guide 91 Fresnel lens 92 Scattering mode liquid crystal 93 Light shielding sheet 14, 14' Folding mirror built-in projection lens 16 Left-right reversing mirror

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03B 21/62 G02F 1/13 505 G02F 1/1333

Claims (7)

(57) [Claims] 1. An image forming means, an illumination optical system for illuminating the image forming means, a projection lens means for enlarging and projecting an image formed on the image forming means, and a light source for projecting light emitted from the projection lens means. Mirror means for bending and guiding the optical path, rear screen means for forming an enlarged image by projecting light guided by the mirror means, and incorporating the image forming means, illumination optical system, projection lens means, and mirror means. Cabinet means, and a screen holding means capable of supporting the rear screen openably and closably, rear projection, a projection display device capable of switching between front projection, in the state where the screen holding means is closed, the rear screen is It is housed inside the cabinet, and the rear screen means continuously selects a scattering state and a transmission state by applying a voltage. Scattering mode liquid crystal that can be
A screen , and the application and non-application of the voltage
A projection display device wherein the screen gain and the viewing angle can be controlled by switching at a cycle faster than the time resolution . 2. An image forming means, and illumination of the image forming means.
An illumination optical system, and an image formed on the image forming unit.
Lens means for enlarging and projecting the image, and the projection lens means
Mirror means for bending and guiding the optical path of the projection light emitted from
And the projection light guided by the mirror means enters and expands.
Rear screen means for forming a large image;
Means, illumination optics, projection lens means, mirror means
Cabinet means to open and close the rear screen
Screen holding means that can be supported,
A Projection display device that can switch between projection and front projection
In the state where the screen holding means is closed,
A rear screen is housed inside the cabinet,
The rear screen means is turned into a scattering state and a transparent state by applying a voltage.
Scattering mode liquid crystal that can continuously select the transient state
Consisting of multiple LCD screens
Each layer is made of polymer dispersed liquid crystal
A projection display device which can be driven independently . 3. An image forming means, and illumination of the image forming means.
An illumination optical system, and an image formed on the image forming unit.
Lens means for enlarging and projecting the image, and the projection lens means
Mirror means for bending and guiding the optical path of the projection light emitted from
If, expansion and projection light guided by the mirrors hand stage is incident
Rear screen means for forming a large image;
Means, illumination optics, projection lens means, mirror means
Cabinet means to open and close the rear screen
Screen holding means that can be supported,
A Projection display device that can switch between projection and front projection
At the front of the rear screen means.
Transparent and opaque parts are periodically arranged in one direction in the plane.
And the opaque portion is mixed with a dichroic dye.
Made of strike-host type liquid crystal, shielded by voltage application
A projection type display device comprising a light shielding sheet means capable of arbitrarily adjusting an effect . 4. An image forming means, an illuminating optical system for illuminating the image forming means, a projection lens means for enlarging and projecting an image formed on the image forming means, and a projection light emitted from the projection lens means. Mirror means for bending and guiding the optical path, rear screen means for forming an enlarged image by projecting light guided by the mirror means, and incorporating the image forming means, illumination optical system, projection lens means, and mirror means. a cabinet means, and a screen holding means which is capable of supporting the rear screen openably rear projection, in a projection type display device capable of switching the front projection, before you error means the rear projection, front projection
A projection type display device having a left-right reversal function of an image in accordance with the switching of the image. Wherein said mirror means comprises at least two or more <br/> Mirror, is composed of the holder means and struts for holding the mirror means, said holder means and struts portion is movably, flat 5. The projection type display device according to claim 4 , wherein both the state of the mirror and the state of the left-right reversing mirror can be configured. 6. The rear projection device according to claim 1, wherein said mirror means is provided for rear projection.
Left-right mirror that the angle between the two mirrors is 180 degrees
The two mirrors during front projection.
Of a flat mirror with an angle of 90 degrees
The projection display device according to claim 5, wherein: 7. A gas discharge bulb as a light source of the illumination optical system.
7. The electronic device according to claim 1, wherein
Item 2. The projection display device according to item 1 .