JP3083859B2 - Projection display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention, high brightness and high contrast of the projection display device relates, a projection display device for enlarging and projecting the image that is particularly formed on the light valve onto a screen using the La light valve It is about.

[0002]

2. Description of the Related Art FIG. 10 shows a conventional projection display device.
This will be described with reference to FIG. In FIG. 10, reference numeral 1 denotes a light source;
0 is a reflecting mirror and a lamp constituting the light source 1 and 2 is a light source 1
3 is a polymer dispersed liquid crystal light valve, 5 is a lens, 6 is an aperture, 4 is a projection lens, and 7 is a screen.

Next, the operation will be described. The light source 1 irradiates a light valve 3 with an illumination light beam 2 which is a parallel light beam. As the lamp 10 of the light source 1, for example, a discharge lamp such as a metal halide lamp or a xenon lamp, or a halogen lamp is used in combination with the reflecting mirror 9. An image is displayed on the surface of the light valve 3 as described later, and a light beam incident on the surface is transmitted or scattered according to the density and color of the image. A light beam (solid line) emitted in parallel from the light valve 3 is condensed on the stop 6 by a lens, and after passing through the stop 6,
The light enters the projection lens 4. The light beam 8 (broken line) scattered by the light valve 3 and passed through the lens 5 is blocked by the stop 6 and cannot enter the projection lens 4. In other words, the aperture 6 blocks unnecessary light (scattered light) and selectively sends only the light flux emitted almost perpendicularly from the light valve 3 to the projection lens 4 side, thereby improving the contrast. The light beam transmitted through the projection lens 4 is projected light 11
It becomes 0, and is enlarged and formed on the screen 7 for viewing.

Next, the structure and operation of the polymer dispersed liquid crystal light valve 3 will be described with reference to FIG. Liquid crystal 32
Are dispersed in the form of water droplets in a matrix of a polymer 33, which is sandwiched between two glass substrates 31a and 31b. After combining the liquid crystal 32 and polymer 33,
Dispersion type liquid crystal (Polymer Dispersed L)
liquid crystal). V when no voltage is applied
= 0 (FIG. 11A), each of the liquid crystal
2 are oriented in an irregular direction. In this state, a difference in refractive index occurs between the polymer 33 and the liquid crystal 32, and the incident light becomes scattered light 2b. On the other hand, a voltage V equal to or higher than the threshold voltage Vth
Is applied (FIG. 11B), the alignment directions of the liquid crystal 32 are aligned. If the refractive index when the liquid crystal 32 is oriented in a certain direction is adjusted in advance to the refractive index of the polymer 33, the incident light 2 becomes the transmitted light 2a without being scattered. As the voltage increases, the degree of coincidence of the alignment direction of the liquid crystal 32 improves, so that the amount of transmitted light also increases.

Next, the configuration of the electrodes of the light valve 3 is shown in FIG.
2 will be described. In FIG. 12, 34 is a pixel, 3
5 is a switching element, 36 is a source electrode, and 37 is a gate electrode. According to this configuration, an arbitrary pixel 34 can be turned on / off by using the switching element 35 by selecting the source electrode 36 and the gate electrode 37 in a known manner. By configuring the electrodes in a two-dimensional array as shown in the figure, a two-dimensional image display device can be formed. In FIG. 12, the red (R), green (G), and blue (B) pixels are shown in a delta array, but other pixel arrays are also known. In addition, in order to provide the pixels with transmittances corresponding to the three primary colors of R, G, and B, R, G, B
Although color filters for transmitting G and B light are provided, illustration of these is omitted.

[0006]

Since the conventional projection display apparatus is constructed as described above, it is necessary to reduce the aperture diameter of the stop 6 immediately before the projection lens 4 in order to increase the contrast. However, in this case, a part of the transmitted light is also lost, and there is a disadvantage that the maximum luminance is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is a light valve including a light-scattering type liquid crystal.
When using, the aperture which is located just before the projection lens
Purpose of more preventing the light beam loss that occurred, to provide a projection display device with higher brightness image display can be realized
And

[0008]

According to the first aspect of the present invention, there is provided a projection type display device which is arranged substantially in parallel with a small interval.
The state of transmission and scattering between the first substrate and the second substrate is controlled.
A material for forming an image by enclosing a material containing a controllable liquid crystal and forming the second substrate with a fiber plate.
Enlarge the image formed on the light valve and the light valve
A projection lens for projecting, and the light valve being connected to the first base.
Light source means for emitting a substantially parallel light beam to illuminate from the plate side
And an incident light that is scattered by the liquid crystal and has a predetermined light receiving angle or more.
Absorb the light beam incident on the fiber plate at the angle of incidence
Shut off the light receiving angle from the image display surface of the light valve
Only the outgoing light flux within the range is selectively incident on the projection lens.
It is something to make . The invention according to claim 2 is characterized in that a fiber plate is provided on the second substrate side of the light valve ,
At the incident angle which is scattered by the liquid crystal and is equal to or larger than the predetermined light receiving angle,
To absorb and block the light beam incident on the iva plate
Therefore, the light receiving angle is determined from the image display surface of the light valve.
Only the outgoing light flux within the range is selectively incident on the projection lens.
It is something to make . A projection display apparatus according to claim 3.
And the first substrate, which is arranged in a substantially parallel
Liquid crystal whose transmission and scattering state can be controlled between the second substrate and the second substrate
And the second substrate is constituted by light reflecting means.
Reflective light valve that forms an image by
And a projection for enlarging and projecting the image formed on the light valve.
A photographing lens and the light valve are illuminated from the first substrate side.
Light source means for emitting a substantially parallel light beam to illuminate,
The first substrate of the light valve is composed of a fiber plate.
And is scattered by the liquid crystal and incident at a predetermined angle or more.
Absorbs and blocks the light beam incident on the fiber plate at an angle
From the image display surface of the light valve to the light receiving angle or less.
Only the outgoing luminous flux inside the projection lens is selectively incident on the projection lens.
It is those that. The invention according to claim 4 is a light valve.
A fiber plate is placed on the first substrate side of
At an incident angle equal to or greater than a predetermined light receiving angle.
Absorbs and blocks the light beam incident on the plate, and
From the image display surface of the
Only selectively enter the projection lens.
It is. In the projection display device according to the invention of claim 5,
The fiber plate consists of a core for transmitting light and its coating.
Multiple unit fibers consisting of cladding and these units
It is composed of a light absorber covering the bundle of fibers . According to the sixth aspect of the present invention, the fiber plate has an optical
And a plurality of bundles of unit fibers each composed of a plurality of cores transmitting light and a light absorber covering each core .

[0009]

[0010]

[Embodiment 1] FIG. 1 is a configuration diagram of a liquid crystal projection display device showing one embodiment of the present invention. In FIG. 1, 1 is a light source, 9 and 10 are reflecting mirrors and lamps constituting the light source 1, 2 is an illuminating light flux emitted from the light source 1, 23 is a glass 31a on an incident side substrate,
The emission side substrate is constituted by a fiber plate 40, and 31a,
A polymer- dispersed liquid crystal light valve sandwiching a polymer- dispersed liquid crystal between 40 and changing into two states of transmission and scattering by an applied voltage, 5 is a lens, 4 is a projection lens, and 7 is a screen.

Next, the operation of the embodiment will be described. The light source 1 irradiates a light valve 23 with an illumination light beam 2 which is a parallel light beam. As the lamp 10 of the light source 1, for example, a discharge lamp such as a metal halide lamp or a xenon lamp, or a halogen lamp is used in combination with the reflecting mirror 9. The illumination light beam 2 is transmitted or scattered in the polymer dispersed liquid crystal portion of the light valve 23 according to the density and color of the image. Figure 1 shows the optical operation principle of the polymer dispersed liquid crystal light valve.
1 as described above.

As will be described later, the fiber plate 40, which is the emission side substrate of the light valve 23, has a structure in which a large number of unit fibers are integrated in a plane. Has the function of selectively transmitting light. Therefore, the light beam that has passed through the fiber plate 40 is substantially only a component parallel to the optical axis 20. That is, it is possible to obtain only a parallel light beam that effectively contributes to image formation, and it is possible to block unnecessary light scattered by the light valve, thereby improving the contrast of the finally obtained projected image. . Details of the fiber plate will be described later.

The light beam 10 transmitted through the fiber plate 40
0 is efficiently incident on the entrance pupil of the projection lens 4 by the lens 5, becomes the projection light 110, and is enlarged and formed on the screen 7.

With such an optical system configuration, the transmitted light of the light valve 23, which is effective for image formation, can be used with almost no loss, so that a high-brightness projected image can be obtained.

Next, the fiber plate 40 will be described in detail. FIG. 2 is a principle diagram of the unit fibers constituting the fiber plate 40. The fiber is a core 41 for transmitting light.
And a cladding 42 of the coating material. Due to the difference in the refractive index between the core 41 and the cladding 42, the light repeats total reflection at the boundary between the core 41 and the cladding 42, as shown by the solid line light 25 in FIG.
Propagating within 1. The incident angle θ1 of light to the core 41 such that the light is totally reflected at the boundary surface between the core 41 and the clad 42 is a case where it is equal to or less than the maximum light receiving angle θmax represented by the following equation. _{NA = n · sinθ max = √} (n 0 2 -n 1 2) (1) where n _0> n ₁ NA: numerical aperture of the fiber theta _max: maximum acceptance angle n _0: refractive index of the core n _1: the cladding refractive index n: light incident at the fiber outside of the refractive index maximum acceptance angle theta _max above angle θ2 is transmitted to the fiber outside as dashed light 26.

FIG. 3 is a plan view showing the structure of the fiber plate 40. The fiber plate 40 has a core 41 and a clad 4
2 and an absorber 43 that further covers the cladding 42. The absorber 43 has an effect of absorbing light that enters the core 41 at an angle equal to or greater than the maximum light receiving angle θmax and leaks to the cladding 42.

The fiber plate 40 shown in FIG.
Although the unit fiber has a hexagonal shape, this may be another shape. Shape and arrangement structure of the core 41,
The pitch and the like correspond to the pixels 34 of the liquid crystal light valve shown in FIG.
If the three are substantially overlapped, the utilization efficiency of the parallel transmitted light is maximized, and a projection display device with higher luminance can be realized.

FIG. 5 is a sectional view of the light valve 23.
When no voltage is applied, the light scattered by the polymer- dispersed liquid crystal layer portion composed of the water-droplet liquid crystal layer 32 and the polymer 33 has many light components that are incident on the fiber plate 40 at a maximum light receiving angle θmax or more. Almost absorbed. Therefore, the transmitted light component of the fiber plate 40 corresponding to the pixel to which no voltage is applied is small. On the other hand, the pixels to which the voltage is applied can transmit through the fiber plate 40 with low loss because the transmitted light is a parallel light flux. In order to effectively absorb the scattered light, it is effective to reduce the maximum light receiving angle θmax in the equation (1). For this, n ₀ and n ₁
Is preferably as close as possible. According to the study by the authors, in order to obtain a contrast sufficient for TV display, it is necessary to satisfy NA ≦ 0.2 (2). For example, when n ₀ = 1.5, NA = √ (n ₀ ² − to satisfy ^{_{n 1 2) ≦ 0.2 (3}} ), is required to be _{1.487 ≦ n 1 <1.5 (4} ).

The liquid crystal does not have to be a polymer dispersed type. When a voltage is applied to a liquid crystal that is regularly aligned when no voltage is applied, the liquid crystal is randomly aligned by a current and becomes cloudy due to a local change in refractive index. Scattering mode (Dynamic S
The liquid crystal may be a liquid crystal of a “catching mode” or a liquid crystal of a phase transition mode in which the liquid crystal changes into two phases of cholesteric and nematic depending on an applied voltage, and takes two states of scattering and transparent, respectively.

In the fiber plate 40, the unit fiber may be constituted by only the core 41 without the cladding layer and the absorber 43 shown in FIG. For example, focusing on light incident from the center of the core 41, light incident at an incident angle θ or more (the light flux 26 indicated by a broken line in FIG.
Absorbed at 3. In order to reduce the reflection at the interface between the absorber 43 and the core 41, it is preferable that the refractive index of the absorber 43 be larger than the refractive index of the core 41. Assuming that the fiber diameter D is 0.02 mm, the fiber length L is 1 mm, the refractive index of the core is n0 = 1.5, and the outside of the exit surface of the fiber is air, the scattered light flux generated in the liquid crystal portion is emitted within 1.7 °. Can be limited to luminous flux.

Embodiment 2 FIG. Next, a second embodiment of the present invention will be described with reference to FIG. 1 is a light source, 9 and 10 are reflecting mirrors and lamps constituting the light source 1, 2 is an illumination light flux, 14R and 14B are dichroic mirrors for color separation, 15B and 15G are dichroic mirrors for color synthesis, 11 and 12 are mirrors, and 23R. , 23G, 23
B is a light valve, 40R, 40G and 40B are fiber plates, 31R, 31G and 31B are incident side substrates, 5
R, 5G, and 5B are lenses, and 4 is a projection lens.

Next, the operation of the second embodiment of the present invention will be described. The illumination light beam 2 is emitted from the light source 1 as a parallel light beam as in the first embodiment. The dichroic mirror 14R reflects red light and transmits blue and green light. The dichroic mirror 14B reflects blue light and transmits green light. Therefore, the light valves 23R, 23
G and 23B are irradiated with red, green and blue illumination light fluxes, respectively. In the light valves 23R, 23G, and 23B, images corresponding to red, green, and blue light are formed by an external circuit (not shown), and the illumination light is transmitted or scattered in the light valves. Light valves 23R, 23G, 23B
Outgoing light of the fiber plates 40R, 40G, 40B
By the action of the above, the light flux becomes only a component substantially parallel to the optical axis 20. The operation of the fiber plates 40R, 40G, and 40B absorbs scattered light (light from non-selected pixels) and efficiently transmits parallel transmitted light (light from selected pixels) as in the first embodiment, thereby ensuring contrast. Is to do. The light beams emitted in parallel from the fiber plates 40R, 40G, 40B are projected by the lenses 5R, 5G, 5B, the dichroic mirror 15B that reflects blue light, the dichroic mirror 15G that reflects green light, and the reflecting mirror 12 as a combined light beam 100 as a projection lens. 4, the image is formed on the screen 7 as the projection light 110, and the enlarged color image is provided for viewing. The light valves 23R, 23
The configuration and operation of G and 23B are almost the same as described above with reference to FIG. 5, but there are no pixels corresponding to red, green, and blue.
The difference is that it is a black and white panel.

With such a configuration, a light beam emitted perpendicularly from the light valve, which is effective for image formation, can be used with little loss, and unnecessary light scattered by the light valve can be blocked. As in the first embodiment, a projection image with high luminance and high contrast is obtained.

Embodiment 3 FIG. FIG. 7 is a configuration diagram of a projection display apparatus according to Embodiment 3 of the present invention. Lens 5 or 5R, 5 shown in the above embodiment
G and 5B are used to efficiently transmit the transmitted light beam 100 of the light valve 23 to the projection lens 4 when the size of the display surface of the light valve 23 is larger than the opening diameter of the projection lens 4. However, when the size of the display surface of the light valve 23 is smaller than the opening diameter of the projection lens 4, as shown in FIG. 7, the lens 5 can be omitted, and light loss and cost can be reduced. Also, the projection lens 4
By using a telecentric optical system, it is possible to realize a projection display device having a good peripheral light amount ratio.

Embodiment 4 FIG. FIG. 8 is a configuration diagram of a projection display apparatus according to Embodiment 4 of the present invention. The light valve 3 according to the present embodiment has glass substrates 31a and 31b similarly to those shown in FIGS.
Thus, a polymer- dispersed liquid crystal composed of the polymer 33 and the liquid crystal 32 is sandwiched. In this case, by disposing the fiber plate 40 on the emission side of the light valve 3,
The same effect as in the first embodiment can be obtained.

Embodiment 5 FIG. FIG. 9 is a configuration diagram of a projection display apparatus according to Embodiment 5 of the present invention. 24 is a fiber plate 4 for the image display side substrate.
Composed of 0, the light reflecting means 16 provided on the opposite side of the substrate, a polymer dispersion type liquid crystal consisting of polymer 33 and the liquid crystal 32 4
It is a reflective liquid crystal light valve sandwiched between 0 and 16. The illumination light beam 2 enters from the fiber plate 40 side. After the illumination light beam 2 passes through the fiber plate 40,
The light scattered in the polymer dispersed type liquid crystal section composed of the liquid crystal 32 and the polymer 33 is again transmitted to the fiber plate 40.
Cannot be transmitted. The non-scattered light is reflected by the light reflecting means 16 and can pass through the fiber plate 40 again.

As shown in FIG. 9, when a reflection type light valve is applied, it is necessary to input and output light by tilting the optical axis 20 with respect to the light valve 24. In order for the illumination light beam 2 to pass through the fiber plate 40 and reach the liquid crystal units 32 and 33, the incident angle and the output angle θ to the light valve 24 are required.
Is set to be equal to or less than the maximum light receiving angle θmax of the fiber plate 40.

In the light valve 24 of the fifth embodiment, the fiber plate 40 is applied to the image display side substrate. However, the image display side substrate may be made of glass. In this case, the fiber plate 40 is installed on the front surface of the image display substrate. I just need.

Embodiments 3, 4, and 5 are so-called single-plate optical systems using only one light valve.
By using three light valves and a dichroic mirror as in the second embodiment, a color projection display device can be realized.

[0030]

As described above in detail, the projection type display device according to any one of the first to sixth aspects has a transmission / scattering state.
By combining a fiber plate with a light valve containing a controllable liquid crystal, it is possible to efficiently obtain only a light beam that exits within a predetermined light receiving angle from the image display surface of the light valve, which effectively contributes to image formation . , To block the scattered light from unnecessary light valves to improve the contrast of the projected image.
Can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram illustrating the principle of a fiber plate used in the present invention.

FIG. 3 is a diagram illustrating a structure of a fiber plate used in the present invention.

FIG. 4 is a diagram illustrating the structure of another fiber plate used in the present invention.

FIG. 5 is a sectional view of a light valve used in the present invention.

FIG. 6 is a configuration diagram showing a second embodiment of the present invention.

FIG. 7 is a configuration diagram showing a third embodiment of the present invention.

FIG. 8 is a configuration diagram showing a fourth embodiment of the present invention.

FIG. 9 is a configuration diagram showing a fifth embodiment of the present invention.

FIG. 10 is a configuration diagram of a conventional projection display device.

FIG. 11 is a diagram illustrating the operation of a light valve used in a conventional projection display device.

FIG. 12 is an explanatory diagram of a TFT active matrix liquid crystal panel used in a conventional projection display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Illumination light beam 4 Projection lens 5 Lens 7 Screen 9 Reflector 10 Lamp 23 Polymer dispersion type liquid crystal light valve 40 Fiber plate

Continuation of front page (56) References JP-A-62-91916 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03B 21/00 G03B 21/14 G02F 1/13

Claims (6)

(57) [Claims] 1. A first disposed kept substantially parallel to minute distance
Controls the state of transmission and scattering between the first substrate and the second substrate
A material containing a possible liquid crystal is encapsulated, and the second substrate is fired.
A light valve for forming an image by configuring in Bapureto, a projection lens for enlarging and projecting the image formed on the light valve, <br/> shown to illuminate the light valve from said first substrate side and a light source means for emitting a parallel light beam is scattered by the liquid crystal wherein an incident angle equal to or greater than a predetermined acceptance angle
Absorbs and blocks the light beam incident on the fiber plate.
A projection display device, wherein only an emitted light beam within the light receiving angle from the image display surface of the light valve is selectively incident on the projection lens. 2. A first disposed maintaining a small gap substantially in parallel
Controls the state of transmission and scattering between the first substrate and the second substrate
A light valve enclosing a material containing a liquid crystal, and a projection lens for enlarging and projecting an image formed on the light valve.
So that the light valve is illuminated from the first substrate side.
Light source means for emitting a substantially parallel light beam, wherein a fiber plate is provided on the second substrate side of the light valve.
It is set up so that it is scattered by the liquid crystal
Absorb the light beam incident on the fiber plate at the angle of incidence
By blocking, the image display surface of the light valve
From the light receiving angle within the acceptance angle
A projection display device characterized by being incident on a lens . 3. A semiconductor device comprising :
Controls the state of transmission and scattering between the first substrate and the second substrate
Encapsulates a material containing possible liquid crystals and reflects light from the second substrate
Means for forming an image by forming
A light valve and a projection lens for enlarging and projecting an image formed on the light valve.
So that the light valve is illuminated from the first substrate side.
Light source means for emitting a substantially parallel light beam, wherein the first substrate of the light valve comprises a fiber plate.
And is scattered by the liquid crystal and incident at a predetermined angle or more.
Absorbs and blocks the light beam incident on the fiber plate at an angle
From the image display surface of the light valve to the light receiving angle or less.
Only the outgoing luminous flux inside the projection lens is selectively incident on the projection lens.
A projection display device characterized by the following: 4. A first disposed kept substantially parallel to minute distance
Controls the state of transmission and scattering between the first substrate and the second substrate
Encapsulates a material containing possible liquid crystals and reflects light from the second substrate
Means for forming an image by forming
A light valve and a projection lens for enlarging and projecting an image formed on the light valve.
So that the light valve is illuminated from the first substrate side.
Light source means for emitting a substantially parallel light beam, wherein a fiber plate is provided on the first substrate side of the light valve.
It is set up so that it is scattered by the liquid crystal
Absorb the light beam incident on the fiber plate at the angle of incidence
Shut off the light receiving angle from the image display surface of the light valve
Only the outgoing light flux within the range is selectively incident on the projection lens.
A projection type display device characterized in that: 5. A fiber transmitting plate for transmitting light.
Multiple unit files consisting of
And a light absorber covering the bundle of these unit fibers
5. The method according to claim 1, wherein
3. The projection display device according to 1 . 6. A fiber plate for transmitting light.
1 through claim, characterized by being configured of a plurality of bundles of unitary fiber made of light-absorbing covering the number of cores and each core
3. The projection display device according to any one of 3 .