JPH11316356A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection type display device capable of projecting a projection image excellent in color-reproducibility. SOLUTION: Relating to this projection type display device, a polarized light beam splitter 3 is used in both a polarized light separating optical system and a analyzing optical system, in both a color separating optical system and a color synthesizing optical system a Phillips type prism 4 consisting of a 1st prism 4A, and 2nd prism 4B, and a 3rd prism 4c is used, and the light source light made incident on the 1st prism 4A of the Phillips type prism 4 is color- separated into light blue light, green light, and red light by a blue-light reflective dichroic film, and further, said green light and red light are color-separated by a green light reflective dichroic film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device for projecting an image formed on a liquid crystal light valve onto a screen.

[0002]

2. Description of the Related Art Conventionally, a full-color projection type display device using a reflection type light valve has been disclosed in JP-A-63-3963.
An apparatus described in Japanese Patent Publication No. 294 is known. FIG.
FIG. 1 shows a configuration diagram of this conventional projection type display device, and the projection type display device will be described with reference to FIG.

That is, in FIG. 3, reference numeral 211 denotes a color separation optical system, and the color separation optical system (Philips prism) 211 includes a first prism 211A, a second prism 211B, and a second prism 211B arranged as shown in FIG. The third prism 211C is provided. On the surface 211e of the first prism 211A, a dichroic film that reflects blue light and transmits light in a longer wavelength range than that is formed by a method such as vapor deposition. A gap is formed between the first prism 211A and the second prism 211B. Further, the second prism 211B and the third prism 21
A dichroic film that reflects red light and transmits green light is similarly formed on the surface 211f between the first and second surfaces.

Accordingly, when white light is incident on the surface 211a, blue light is reflected on the surface 211e, and the reflected blue light travels toward the emission surface 211b. Also,
The green light of the light transmitted through the surface 211e is the surface 211f
To the emission surface 211d. In addition, surface 211
The red light reflected at f goes to the emission surface 211c.

In the figure, reference numerals 212, 21
Reference numerals 3 and 214 each have a structure in which a reflective layer 215, 216, or 217 made of a dielectric is formed on the back surface of the transmission light valve, respectively, and is configured as a reflection light valve.

Further, in this figure, reference numeral 221 denotes a polarization beam splitter, which is arranged on the set optical axis O of the color separation optical system 211. Reference numeral 222 denotes a collimation lens, and a white light source 223 such as a halogen lamp is arranged at a substantially focal position of the collimation lens 222.

In the conventional projection display apparatus having the above configuration, the light beam emitted from the white light source 223 enters the collimation lens 222 to become a parallel light beam, and is reflected by the polarization splitting unit of the polarization beam splitter 221. S-polarized light enters the color separation optical system 211.

The linearly polarized light (S-polarized light) incident on the color separation optical system 211 is color-separated into each color light, and is incident on each of the light valves 212, 213, 214 for each color light. The light is spatially modulated, is reflected by changing the polarization direction by 90 degrees, is incident on the color separation optical system 211 in the reverse direction of the optical path, and the optical system 211 acts as a color combining optical system and is combined by the optical system 211. The synthesized light exits from the surface 211a and is
Component converted at 2,213,214 (P-polarized component)
Is incident on the polarization beam splitter 221, is analyzed by the polarization splitting unit, passes therethrough, and passes through the projection lens 224.
Is projected on the screen 225.

[0009]

However, such a conventional projection display apparatus has a problem that the color balance of the projected image is poor and a problem that the projected image is distorted.

The present inventors have studied the above-mentioned projection type display device and found that the above-mentioned problem exists in the basic structure of the projection type display device. In other words, it has been found that these problems can be solved by changing the configuration and arrangement of the dichroic mirror used for color separation and color synthesis.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention described in claim 1 provides a light source and a polarization separator for separating the light source light emitted from the light source into linearly polarized light having different vibration directions. An optical system, a color separation optical system that separates one polarized light separated by the polarization separation optical system into B light, G light, and R light, and converts each color light separated by the color separation optical system into each color. A reflection type light valve arranged for each color light that is modulated and emitted based on a signal; a color synthesis optical system that performs color synthesis of light emitted from each color light valve and emits the light; and a color synthesis optical system. In a projection display apparatus having an analysis optical system that extracts modulated light from the combined light, and a projection optical system that projects the analysis light by the analysis optical system, the polarization separation optical system and the analysis optical system are shared. Polarization beam splitter In addition, the color separation optical system and the color synthesis optical system are a Phillips prism composed of a first prism, a second prism, and a third prism that are shared, and the light source light incident on the first prism of the Phillips prism. Is color-separated into B light, G light and R light mixed light by the B light reflecting dichroic film.
The G light and the R light are color-separated by a G light reflecting dichroic film to form a projection display device.

According to a second aspect of the present invention, there is provided a light source, a polarization separation optical system that separates the light source light emitted from the light source into linearly polarized light having different vibration directions, and the polarization separation optical system. A color separation optical system that separates one polarized light into B light, G light, and R light; and each color light that is modulated by the color separation optical system based on each color signal and emitted. A reflective light valve arranged,
A color combining optical system that combines and emits light emitted from each of the color light valves, a light analyzing optical system that extracts modulated light from the combined light by the color combining optical system, and a light that is analyzed by the light analyzing optical system. And a projection optical system having a projection optical system, the polarization separation optical system and the analysis optical system are dual-purpose polarization beam splitters, and the color separation optical system and the color synthesis optical system are dual-purpose. A Philips prism composed of one prism, a second prism and a third prism, and the light source light incident on the first prism of the Philips prism is B light, G light and R light by the B light reflecting dichroic film. Color separation into mixed light,
Further, the G light and the R light mixed light are color-separated into R light and G light by a G light reflecting dichroic film, and the light beam is the light source light and is incident on the polarizing beam splitter and is polarized and separated. The polarized light that has passed through the color separation optical system is emitted from the light pulp for each color, and the modulated light of the combined light by the combining optical system is the light reflected by the polarization separation unit of the polarization beam splitter. And a projection type display device set so as to obtain the same.

According to a third aspect of the present invention, in addition to the configuration of the second aspect, the modulated light of the combined light incident on the polarization beam splitter is bonded to the adhesive at the polarization separation section of the polarization beam splitter. It is characterized in that it is set so that it can be reflected without passing through a layer.

[0014]

FIG. 1 is a block diagram showing a projection type display apparatus according to the present invention.

That is, light from a light source 1 composed of a concave mirror composed of an elliptical mirror and a lamp is emitted, and this light is converted into a substantially parallel light beam by a shaping optical system composed of lenses 11 and 12. Both lenses 1
The direction of the optical axis is changed to a right angle by the bending mirror 2 arranged between the first and second mirrors 12.

The substantially parallel light beam from the shaping optical system is incident on a polarization beam splitter 3 as a "polarization separation optical system and an analysis optical system", and is transmitted through the polarization beam splitter 3 as it is. Polarization separation unit 3
e is polarized and separated into S-polarized light that is reflected and discarded.

The P transmitted through the polarizing beam splitter 3
The polarized light is incident on a prism group constituting the Philips prism 4 as a “color separation optical system and a synthesis optical system”.

Here, the first prism 4A is provided with an incident surface 4a.
Incident on the first prism 4A travels as it is, passes through the B light (blue light) reflected by the B light reflecting dichroic film provided on the surface 4c, and exits from the surface 4c of the first prism 4A. It is color-separated into mixed light of G light (green light) and R light (red light).

The B light reflected by the B light reflecting dichroic film provided on the surface 4c travels, undergoes total reflection at the surface 4a of the first prism 4A, travels, and emerges from the exit surface 4b. Then, the light enters the reflective light valve 5B for B light disposed near the emission surface 4b.

The G, R mixed light emitted from the surface 4c of the first prism 4A is incident on the second prism 4B having the surface 4d through the gap between the surface 4a of the first prism 4A and the air. proceed. A G light reflecting dichroic film is provided on the surface 4e between the second prism 4B and the third prism 4C, and is color-separated into G light reflected by the film and R light transmitted and traveling.

The G light reflected by the dichroic film 4e travels through the second prism 4B, is totally reflected by the surface 4d constituting the gap, travels, and emerges from the exit surface 4f. The light enters the reflection light valve 5G for G light disposed near the emission surface 4f.

Further, as described above, the R light transmitted through the G light reflecting dichroic film provided on the surface 4e between the second prism 4B and the third prism 4C enters the third prism 4C, travels, and exits. It is emitted from the surface 4g. Then, the emitted R light is incident on the R light reflective light valve 5R disposed near the emission surface 4g.

Here, the reflection type light valves 5B, 5G,
5R will be described.

As the reflection type light valve, an optical writing type reflection type light valve and an electric writing type reflection type light valve are known. In this embodiment, an electric writing type is used. The light valve is arranged such that the arrangement of liquid crystal molecules of the liquid crystal layer arranged on the incident surface side of each pixel for each of the pixels owned by the light valve and the voltage applied between the liquid crystal layers for each pixel
A switching element such as an FT is switched in accordance with each color signal to be selectively applied and changed to be used as a modulation element.

From the above, the incident light that has entered the selected pixel is reflected by the reflective layer via the liquid crystal modulation layer, and is again emitted through the modulation layer, and becomes the polarized light (P-polarized light) incident. The light is converted into polarized light (S-polarized light) having a vibration direction different by 90 degrees and emitted.

On the other hand, the polarized light that has entered the liquid crystal layer portion that has entered the pixel portion where switching has not been selected rotates in accordance with the twisted structure of the liquid crystal molecules, is reflected by the reflective layer, travels backward through the liquid crystal molecules, and travels with the incident light. The light is reflected and emitted with the same polarization.

By the function of the reflection type light valve, each color light which reflects the modulated light as the S-polarized light different from the incident polarized light (P-polarized light) as the emitted light at the portion corresponding to the modulated pixel portion. The reflected light from the bulb travels in the opposite direction to that described above, and exits the prism group 4 as the combined light of each color. That is, the prism group 4 functions not only as a color separation optical system but also as a color synthesis optical system.

The emitted combined light enters the polarization beam splitter 3 again, and is modulated light (S-polarized light) reflected by the polarization splitter 3e of the polarization beam splitter 3 and unmodulated light transmitted and discarded. And undergoes an analysis.

The S-polarized light that has been analyzed and reflected is
The light enters the projection lens 13 and projects a full-color projection image on the screen 6.

Next, the dichroic film employed in the projection type display device according to the embodiment of the present invention will be examined in comparison with that of the conventional projection type display device.

In the projection type display device according to the present invention, the B light reflecting dichroic film provided on the surface 4c is the same as the B light reflecting dichroic film in the conventional example, and it is not necessary to compare.

In the projection type display device according to the present invention, the surface 4
The characteristic of the G-light reflecting dichroic film provided in e is that the light incident on this dichroic film does not already have light in the B light wavelength region,
A dichroic film having a characteristic of reflecting the light and the G light wavelength region may be used.

In the R light reflecting dichroic film disposed on the surface 211f in the conventional example, the light incident on the film does not include the light in the B light wavelength region as described above.
It is necessary to form a dichroic film having a property of transmitting light in the B light and G light wavelength regions and reflecting light in the R light wavelength region.

FIG. 2 shows the characteristics of the G light reflecting dichroic film according to the embodiment of the present invention, and FIG. 4 shows the characteristics of the R light reflecting dichroic film according to the conventional example.

Incidentally, the film configuration of the dichroic film according to the embodiment of the present invention has a configuration of glass member / (H / 2 · L · H / 2) n, where H and L are high, respectively. A refractive index film (TiO2: refractive index n = 2.20) and a low refractive index film (Si
O2: a λ / 4 film having a refractive index of n = 1.47).

In the present embodiment, a value of 10 is set as n,
The characteristics were obtained when BAC4 glass having a refractive index of 1.57 was used as the glass. At this time, the total thickness of the high refractive index film is 5
75 nm, the total thickness of the low refractive index film is 874 nm, and the total total thickness is 1449 nm.

The dichroic film of the prior art is also a film having the above-mentioned structure, and shows the characteristics when the glass substrate is adopted by adopting 10 as n. The high refractive index film thickness of this dichroic film is 771 nm, and the low refractive index film thickness is 1171.
nm, and the total film thickness is 1942 nm.

As can be understood from these two characteristics, in the R light reflecting dichroic film according to the conventional example, as shown in FIG. 4, there is a ripple indicating deterioration of the transmission characteristic in the G light wavelength region. This ripple means that a part is reflected, and the reflected G light part is mixed with the R light and is incident on the R light light valve 213.
As a result, the color balance of the projected image deteriorates.

On the other hand, in the G light reflecting dichroic film according to the embodiment of the present invention, as shown in FIG. 2, there is no large ripple in transmission characteristics in the R light wavelength region, and the G light light valve 5G It is possible to project a projection image with good color balance without mixing the R light.

In the above-described conventional dichroic film, it is possible to remove a ripple existing in the wavelength region of G light. To this end, the number of high refractive index and low refractive index films constituting the dichroic film is required. Must be increased, which leads to an increase in cost.

Further, in the projection type display device according to the present embodiment, in the polarization beam splitter 3 used also as a polarization separating and analyzing optical system for the light source light, the light source light is incident on the polarizing beam splitter 3. Then, the transmitted P-polarized light is made incident on the light valves 5B, 5G, and 5R for each color as illumination light, and the S-polarized light is discarded.

In the case of the projection type display apparatus according to the present embodiment, the modulated light from the light valves 5B, 5G, 5R for each color light is emitted as S-polarized light. S reflected by the part 3e
The polarized light is guided to the projection lens system 13 as projection light.

The polarizing beam splitter 3 has a right-angled triangular prism-shaped glass prism 3a,
The prism 3a is composed of a polarization splitting film, an adhesive layer, and a glass prism 3b having the same shape as described above, which are formed of a dielectric multilayer film formed directly on the slope of the prism 3a. The polarization separation section 3e is formed of a polarization separation film and an adhesive layer.

Therefore, in the present embodiment, the combined light enters the one glass prism 3a, travels, and is reflected and analyzed by the polarization separation film, so that it passes through the adhesive layer. Is not configured. Therefore, the analysis light can be introduced into the projection lens 13 without being affected by the thickness unevenness of the adhesive layer at all.

In the conventional example, each color light valve 21
2, 213, 214, the modulated light is transmitted through the polarization beam splitter 221 and is analyzed, so that the adhesive layer forming the polarization splitting portion of the polarization beam splitter 221 is removed. Because of the direct passage, there was a problem that distortion of the projected image was formed due to unevenness in the thickness of the adhesive layer and unevenness in the refractive index, but this problem was also solved by the configuration of the projection display device according to the present embodiment. Can solve the problem.

The polarizing beam splitter is composed of two prisms. Even in the same lot, there is a slight difference in the refractive index between the two prisms. In a conventional configuration of a projection display apparatus using S-polarized light as incident light on a polarization beam splitter, light emitted from a color separation optical system is P-polarized light, and a projected image passes through two prisms. With this configuration, if there is a difference in the refractive index between the prisms as described above, coma and astigmatism are generated, and there is a problem that the imaging performance is reduced.

However, as in the configuration of the present invention, P
When polarized light is used as light incident on a polarizing beam splitter, the light exiting the color separation optical system is S-polarized light, and the projected image transmits only one prism. Therefore, there is an effect that the projected image is not affected by the difference in the refractive index and the imaging performance is not reduced.

[0048]

As described above, according to the projection type display device of the invention described in each claim, there is an effect that a projection type display device capable of projecting a projected image with good color reproducibility can be provided. be able to.

According to the third aspect of the present invention, in addition to the above-described effects, there is an effect that a projection image without distortion can be projected.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a projection display device according to an embodiment of the present invention.

FIG. 2 is a transmission characteristic diagram of a dichroic film used in the projection display according to the embodiment.

FIG. 3 is a configuration diagram of a conventional projection display device.

FIG. 4 is a transmission characteristic diagram of a dichroic film used in a conventional projection display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Light source 2 Folding mirror 3 Polarization beam splitter (polarization separation optical system, analysis optical system) 3e Polarization separation part 4 Phillips prism (color separation optical system, synthesis optical system) 4A, 4B, 4C Construct a Phillips prism Prism 5B, 5G, 5R Reflective light valve 11, 12 Shaping lens 13 Projection lens (projection optical system)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03B 33/12 G03B 33/12

Claims (3)

[Claims] 1. A light source, a polarization separation optical system that separates light source light emitted from the light source into linearly polarized light having different vibration directions, and one of the polarized lights separated by the polarization separation optical system is B light;
A color separation optical system for color separation into G light and R light, and a reflection type light valve arranged for each color light to be emitted by modulating each color light separated by the color separation optical system based on each color signal and emitting the light. A color combining optical system that combines and emits light emitted from each of the color light valves, a light analyzing optical system that extracts modulated light from the combined light by the color combining optical system, and a light analyzing by the light analyzing optical system A projection optical system for projecting light,
In the projection type display device, the polarization separation optical system and the analysis optical system are dual-purpose polarization beam splitters, and the color separation optical system and the color synthesis optical system are also a first prism, a second prism, and a second prism. A Philips prism composed of three prisms, wherein light source light incident on the first prism of the Philips prism is B light reflected by a B light reflecting dichroic film;
A projection display device, wherein the G light and the R light are color-separated into mixed light, and the G light and the R light are color-separated by a G light reflecting dichroic film. 2. A light source, a polarization separation optical system that separates the light source light emitted from the light source into linearly polarized lights having different vibration directions, and one of the polarized lights separated by the polarization separation optical system is B light;
A color separation optical system for color separation into G light and R light, and a reflection type light valve arranged for each color light to be emitted by modulating each color light separated by the color separation optical system based on each color signal and emitting the light. A color combining optical system that combines and emits light emitted from each of the color light valves, a light analyzing optical system that extracts modulated light from the combined light by the color combining optical system, and a light analyzing by the light analyzing optical system A projection optical system for projecting light,
In the projection type display device, the polarization separation optical system and the analysis optical system are dual-purpose polarization beam splitters, and the color separation optical system and the color synthesis optical system are also a first prism, a second prism, and a second prism. A Philips prism composed of three prisms, wherein light source light incident on the first prism of the Philips prism is B light reflected by a B light reflecting dichroic film;
The G light and the R light mixed light are color-separated into G light and R light mixed light. Further, the G light and the R light mixed light are color-separated into R light and G light by a G light reflecting dichroic film. The polarized light transmitted through the polarization beam splitter, which is incident on the splitter and polarized and separated, is incident on the color separation optical system, and is the light emitted from the light pulp for each color, which is the modulated light of the combined light by the combining optical system. Is a projection type display device which is set so as to be obtained by reflected light from a polarization splitting section of the polarization beam splitter. 3. The polarization beam splitter according to claim 2, wherein the modulated light of the combined light incident on the polarization beam splitter is set to be reflected by the polarization beam splitter of the polarization beam splitter without passing through an adhesive layer. Item 3. The projection display device according to Item 2.