JP2000206481A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress heat generation of a polarizing means of a liquid crystal light valve and to satisfactorily maintain the characteristics thereof, by having the polarizing means which allows the transmission of mainly the light of one polarization axis component and reflects mainly the light of another polarization axis component. SOLUTION: A light from a light source side is rendered as incident lights 501 and 502 and an absorption type polarizing plate 503 allows the transmission of mainly the light of, for example, a P-polarized light component of the incident light and absorbs mainly the light of an S-polarized light. The P-polarized light transmitted through the absorption type polarizing plate 503 is made incident on a liquid crystal panel 504. TN-type liquid crystals of a are used for the liquid crystal panel 504 and the incident light on pixels which are not impressed with voltage on the liquid crystals is rotated in the polarization axis by about 90 deg. and is emitted as an S-polarized light 509. The reflection polarized light plate 505 allows the transmission of mainly the light of the P-polarization axis component and reflects mainly the light of the S- polarization axis component. When the liquid crystal light valve is used as a normally white mode, the transmission axis of the polarizing plate 505 is set at the S-polarized light and the light 509 emitted as the S-polarized light from the liquid crystal light valve 504 is transmitted as is.

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 (also called a liquid crystal projector) using a liquid crystal light valve constituted by a liquid crystal panel.

[0002]

2. Description of the Related Art A liquid crystal projector 1100 shown in FIG.
Is an example of a general projection type projector using a transmission type liquid crystal panel as a light valve. In FIG.
Light emitted from a lamp unit 1102, which is a light source, is reflected by a mirror 11061 to form a light guide 11
The light is incident on the light source 04 and is separated into three primary color lights R, G and B of red, green and blue by two dichroic mirrors 11081 and 11082 inside. Dichroic mirror 110
The blue color light B separated by 82 is
And enters the liquid crystal light valve 1110B. The green light G reflected by the dichroic mirror 11081 enters the liquid crystal light valve 1110G. The red color light R transmitted through the dichroic mirror 11081 is reflected by the two mirrors 11063 and enters the liquid crystal light valve 1110R.

[0003] Three liquid crystal light valves 1110R, 11
10G and 1110B form an image by modulating incident light according to image information of each color. The respective liquid crystal light valves 1110R, 1110G and 1110B
The light modulated by the dichroic prism 11
It is incident on 12 from three directions. Dichroic prism 1
Numeral 112 denotes an X-shaped two-wavelength reflecting film that is bonded with an adhesive so that the vertical angles of the four right-angle prisms are aligned with each other, and along the bonding surface.
Therefore, the red color light R is reflected toward the projection lens 1114 by the one wavelength selective reflection film. Further, the blue color light B is reflected toward the projection lens 1114 by the other wavelength selective reflection film. On the other hand, the green G color light G passes through the two types of wavelength selective reflection films and reaches the projection lens 1114. That is, three liquid crystal light valves 1110R, 1
Images formed by 110G and 1110B are combined by a dichroic prism 1112 and projected on a projection surface such as a screen through a projection lens 1114.

[0004]

FIG. 9 is a schematic view of a liquid crystal light valve. Conventionally, a liquid crystal light valve 1110
As shown in FIG. 9, R, 1110G, and 1110B are spaced apart from the light incident surface of the liquid crystal panel 804, and the number of incident polarizers is eight.
03, and the output side polarizing plate 805 is connected to the liquid crystal panel 80.
4 on the light exit surface.

In FIG. 9, the incident side polarizing plate 803 transmits, for example, light 801 having a P-polarization axis component (the symbol in the drawing indicates a P-polarization axis), but light having an S-polarization axis component of the incident light. 802 (the symbol in the figure indicates the S polarization axis) absorbs.
The P-polarized light 801 transmitted through the polarizing plate 803 is incident on the liquid crystal panel 804. The liquid crystal panel 804 uses TN-type liquid crystal. Light (P-polarized light 801) incident on a pixel to which no voltage is applied to the liquid crystal is emitted as S-polarized light 809 after the polarization axis is rotated by approximately 90 °. You. On the other hand, light (P-polarized light 801) incident on a pixel applied with a voltage to the liquid crystal
Is emitted as P-polarized light 808 as it is. 80
Reference numeral 5 denotes an output side polarizing plate. If the transmission axis of the polarizing plate 805 is set to S-polarized light,
Light 809 emitted as polarized light is transmitted as it is. On the other hand, light 808 emitted from the liquid crystal panel 804 as P-polarized light is absorbed by the polarizing plate 805. In the liquid crystal panel 804, the degree of twist of the liquid crystal can be controlled by controlling the voltage applied to the liquid crystal for each pixel based on the image information of each color.
It is possible to control the amount of rotation of the polarization axis of the light 801 that is transmitted through and incident on the optical axis 801. Thus, the output side polarizing plate 805
Can be controlled for each pixel, and an image is formed.

The light 808 emitted from the liquid crystal panel as P-polarized light is absorbed by the emission-side polarizing plate 805.

Conventionally, the polarizing plate is of a type that absorbs an opaque polarization axis (hereinafter, referred to as an absorption type polarizing plate), so that about half of the light emitted from the liquid crystal panel 804 is converted to the polarizing plate. Is absorbed and converted to heat,
There is a problem that the heat degrades the polarization characteristics of the polarizing plate. In addition, the heat generated by the polarizing plate is
In this case, the characteristics of the liquid crystal are changed, and the leakage current of the thin film transistor (TFT) disposed in the pixel of the liquid crystal panel is increased, so that display unevenness occurs in the screen or the contrast is deteriorated. There was also a problem to do.

Therefore, in the conventional projection display device, since the exit side polarizing plate of the liquid crystal light valve absorbs about half of the incident light and generates heat, measures such as using a liquid crystal having high heat resistance are taken. Was needed. That is, the physical properties of the liquid crystal, such as the refractive index, the dielectric anisotropy, and the elastic coefficient, change with temperature, and the change becomes larger as it approaches the phase transition point (NI point) to the isotropic phase. A liquid crystal having a high I point is used. In addition, by mixing dozens of high NI point materials, the threshold voltage, response speed, etc. are within a range having sufficient performance, and the NI point is in a state where a liquid crystal material higher than 100 ° C. is obtained. there were. Therefore, the cost of the liquid crystal is high, and the cost of the liquid crystal panel has been increased.

In recent years, there has been a tendency to increase the brightness of a light source lamp in order to brighten an image projected on a screen, thereby increasing heat generation in a liquid crystal light valve. In order to cool the heat generated by the liquid crystal light valve, a cooling fan that cools the output side polarizing plate and the liquid crystal panel is provided. Was needed.

Further, since about half of the light emitted from the liquid crystal panel is absorbed by the exit-side polarizing plate and converted into heat,
Light utilization efficiency was very poor, and a bright display could not be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art, and there is provided a projection display apparatus which suppresses heat generation of a polarizing means of a liquid crystal light valve and maintains good characteristics of the liquid crystal light valve. The purpose is to provide. It is another object of the present invention to provide a projection display device in which the efficiency of using light from a light source lamp is improved.

[0012]

A first projection type display device according to the present invention comprises: a light source; a polarization conversion means capable of aligning light from the light source with light having one polarization axis component and emitting the light; A light valve for modulating light emitted from the polarization conversion means, and projection optical means for projecting light modulated by the light valve, wherein the light valve includes a liquid crystal panel, and at least a light exit side of the liquid crystal panel. It is characterized by having a polarizing means arranged and mainly transmitting light of one polarization axis component and mainly reflecting light of the other polarization axis component.

A second projection type display device according to the present invention comprises:
A light source, a light valve for modulating light from the light source, and projection optical means for projecting light modulated by the light valve, the light valve comprising: a liquid crystal panel; and a light emitting side of the liquid crystal panel. And a reflective polarizing plate that mainly transmits light of one polarization axis component and mainly reflects light of the other polarization axis component, and is disposed on the light incident side of the liquid crystal panel. It is characterized by comprising polarizing means for mainly transmitting light and mainly absorbing light of the other polarization axis component.

A third projection type display device according to the present invention comprises:
A light source, and a light valve that modulates light from the light source,
Projection optical means for projecting light modulated by the light valve, wherein the light valve is disposed on a liquid crystal panel and at least on a light emission side of the liquid crystal panel, and mainly transmits light of one polarization axis component. The liquid crystal panel has a reflection means for mainly reflecting light of the other polarization axis component, the liquid crystal panel sandwiches liquid crystal between a pair of substrates, and on one of the substrate inner surfaces arranged on the light incident side, A switching element and a pixel electrode connected thereto are formed in a matrix, and a light-shielding layer is provided on the other substrate at a position corresponding to the switching element.

According to the first to third projection display devices according to the present invention, light of one polarization axis component is mainly transmitted to the emission side of the liquid crystal panel, and light of the other polarization axis component is mainly transmitted. It is characterized in that a polarizing means for reflecting light is provided with a polarizing plate. Incidentally, such a polarizing means is generally referred to as a “reflective polarizing plate”.
Also known as Since the polarizing means generates less heat due to light absorption than a conventional light absorbing polarizing plate, it is possible to prevent the polarization characteristics of the polarizing means from deteriorating due to heat and to prevent the liquid crystal panel from being affected by heat. In addition, since heat generation is drastically reduced, in some cases, cooling means may be eliminated.
Alternatively, the cooling mechanism can be simplified, for example, it is not necessary to take complicated measures to increase the cooling efficiency of the cooling means. In addition, at least a part of the light of the other polarization axis component reflected by the polarizing means has a slight shift in its optical path as re-reflection is repeated between the polarizing means and the light source. Therefore, when the light again enters the liquid crystal panel, the light is incident on a region different from the first region. In other words, the light is transmitted through the liquid crystal panel and eventually becomes light in the polarization axis direction that is transmitted through the polarizing means. Therefore, the light use efficiency can be increased as compared with the related art.

In one embodiment of the first projection type display device of the present invention, the projection type display device is provided between the polarization means and the projection means, and mainly transmits the light of the one polarization axis component,
A polarizing plate (hereinafter, referred to as an absorption polarizing plate) mainly absorbing light having a polarization axis component different from the one polarization axis component is provided.

According to this aspect, the light of the other polarization axis component that has not been completely reflected by the polarizing means can be absorbed by the absorption type polarizing plate. Therefore, the light emitted from the light valve becomes light having a polarization axis component having a higher degree of polarization, so that the contrast characteristics of an image projected from the projection optical unit are improved. Note that this aspect can also be adopted for the second and third projection display devices.

In another aspect of the first projection type display device of the present invention, the light valve is disposed on a light incident side of the liquid crystal panel, and a light of a polarization axis component emitted from the polarization conversion means. And a polarizing plate mainly transmitting light of the other polarization axis component and mainly absorbing light of the other polarization axis component.

According to this aspect, according to this aspect, the light component which has not been completely converted by the polarization conversion device is absorbed by the absorption type polarizing plate. Therefore, light incident on the liquid crystal panel becomes light of a polarization axis component having a higher degree of polarization, and the contrast characteristic of an image projected from the projection optical unit is improved.

In another aspect of the first projection type display device of the present invention, the light source comprises a light source lamp for emitting light, a light emitted from the light source lamp, and a light reflected by the polarizing means. A reflecting mirror for reflecting the light toward the polarizing means.

In this aspect, the light of the other polarization axis component reflected by the polarizing means is re-reflected by the reflecting mirror, and a slight shift occurs in the optical path while reciprocating between the polarizing means and the reflecting mirror. Therefore, when the light is again incident on the liquid crystal panel, the light is incident on a region of the liquid crystal panel different from the first one, that is, the light is transmitted in the polarization axis direction by the liquid crystal panel sometime. Therefore, the light use efficiency can be increased as compared with the related art. Note that this aspect can also be adopted for the second and third projection display devices.

According to another aspect of the first projection type display device of the present invention, a separating means for separating the light from the light source into a plurality of color lights, and modulating the color lights separated by the separating means respectively. A plurality of said light valves,
Synthesizing means for synthesizing the color lights modulated by the plurality of light valves.

In this embodiment, since the polarizing means is provided on the emission side of each light valve, all the separated color lights can be used effectively. Note that this aspect can also be adopted for the second and third projection display devices.

In the first, second, and third projection display devices of the present invention, and in each of these aspects, the polarizing means is:
A first film having different refractive indices in a first axial direction and a second axial direction orthogonal to the first film, and a first film having a refractive index in the first axial direction and a refractive index in the second axial direction which are different from each other; It is a multilayer structure film in which a second film having a refractive index substantially equal to the refractive index in the second axial direction is alternately laminated.

By doing so, a flat polarizing means can be formed, and the projection display device does not become large. Further, the multilayer structure film serving as the polarizing means in the present invention can be adhered or stuck to the outer surface of the substrate of the liquid crystal panel. This eliminates the need for a holding member for holding the polarizing means. Note that, as described above, since the polarizing means has little light absorption and hardly generates heat, there is no concern about the influence of heat on the liquid crystal panel.

Further, in the third projection type display device of the present invention, when light is reflected from the polarizing means toward the liquid crystal panel, the light is emitted from the output side of the switching element so as not to enter the switching element, especially the thin film transistor. Since the light-shielding film is disposed at the position, the deterioration of the characteristics of the liquid crystal panel can be suppressed. That is, even if the polarizing means is arranged on the light emission side of the liquid crystal panel, a light leak current flows through the silicon layer of the thin film transistor in the liquid crystal panel, and the charge retention characteristics of each pixel are deteriorated, and the contrast of the liquid crystal panel is reduced. Can be prevented. Therefore, it is possible to prevent the characteristic deterioration of the liquid crystal panel while improving the light use efficiency.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment (Description of Configuration of Projection Display Device) FIG. 1 is a schematic configuration diagram showing a main part of a projection display device according to a first embodiment. This projection display device includes a light source 10, dichroic mirrors 13 and 14, and reflection mirrors 15, 16, and 17.
, Relay lenses 18, 19, 20 and three liquid crystal light valves (23, 29, 30), (24, 31, 3).
2), (25, 33, 34), a cross dichroic prism 26, and a projection lens 27.

The light source 10 is a light source lamp 11 such as a metal halide lamp or a mercury lamp that causes an arc discharge between two electrodes.
And a reflecting mirror (reflector) 12 having a parabolic surface such as a semicircular shape or a semi-elliptical shape for reflecting toward the dichroic mirror 13 so that the light generated by the arc discharge becomes substantially parallel light. Become.

The dichroic mirrors 13 and 14 have a function as color light separating means for separating a light beam from a light source into three color lights of red, blue and green.

The first dichroic mirror 13 having the function of separating red light transmits the red light component of the light beam emitted from the light source 10 and reflects the blue light component and the green light component. The transmitted red light is reflected by the reflecting mirror 17, and the liquid crystal light valve for red light (23,
29, 30). On the other hand, of the blue light and the green light reflected by the first dichroic mirror 13, the green light is reflected by the second dichroic mirror 14 which reflects green light, and the liquid crystal light valves for green light (24, 3).
1, 32). On the other hand, the blue light also passes through the second dichroic mirror 14.

In this embodiment, the optical path length of blue light is the longest of the three color lights. Therefore, for blue light, a light guide means 22 composed of a relay lens system including an incident lens 18, a relay lens 19, and an exit lens 20 is provided after the second dichroic mirror 14. Thus, the optical distance is shortened to suppress the light loss. That is, the blue light is transmitted through the green light-reflecting second dichroic mirror 14 and then guided to the relay lens 19 via the incident lens 18 and the reflection mirror 15. Further, the light is reflected by the reflection mirror 16, guided to the emission lens 20, and is incident on the liquid crystal light valve for blue light (25, 33, 34).

Next, the three color lights incident on each light valve are modulated by each light valve according to an image signal (image information) given from an external control circuit (not shown), and an image of each color component is formed. The light is emitted as a color light flux having a light intensity corresponding to the information for each pixel.

Among the liquid crystal light valves, the liquid crystal panel 2
Each of the light modulators 3, 24, and 25 has a function as a light modulator that forms an image by modulating three color lights in accordance with a given image signal (image information). Each liquid crystal panel is a liquid crystal panel in which TN (Twisted Nematic) liquid crystal is sealed between a pair of substrates. Each pixel formed in a matrix has a thin film transistor (TFT) or a two-terminal element (for example, Switching elements such as MIM)
A pixel electrode connected thereto is arranged. A liquid crystal panel using a TFT will be described in more detail. On one substrate, scanning signal lines and data signal lines are arranged so as to intersect in a matrix, and a pixel region partitioned thereby has scanning signal lines. A TFT whose source is connected to the gate and the data signal line, and a pixel electrode which is connected to the drain of the TFT. On the other hand, a counter electrode is formed on the other substrate, and an image signal is applied to a pixel electrode from a data signal line through a TFT that is turned on by a scanning signal,
A voltage based on an image signal is applied to a liquid crystal layer sandwiched between the pixel electrode and the counter electrode. The orientation of the liquid crystal molecules is controlled in accordance with the applied voltage, whereby the rotation of the polarization axis of the incident color light is controlled and modulation is performed. The basic configuration and driving method of this liquid crystal panel are the same as the configuration and driving method of a conventionally known active matrix type liquid crystal panel.

Before and after the liquid crystal panels 23, 24, and 25, respectively, absorption polarizers and reflective polarizers (29, 30), (31, 32), and (33, 34) as polarizing means.
Are arranged, and an absorption-type polarizing plate is adhered or adhered to the outer surface of the light-incident side substrate of the liquid crystal panel, and a reflective polarizer is adhered or adhered to the outer surface of the light-exiting-side substrate. Incident type polarizing plate 29, 3 on the incident side
Reference numerals 1 and 33 denote light in a predetermined direction of random light emitted from the light source 10 (for example, light of a polarization component that transmits P-polarized light vibrating in a direction parallel to the plane of the drawing of FIG. It is an absorption-type reflective polarizing plate that absorbs (S-polarized light that vibrates in the direction perpendicular to the plane of the paper of the drawing).
Reference numeral 25 controls the rotation of the polarization axis of the light transmitted through the absorption polarizer according to the image signal. For example, when P-polarized light is transmitted through an absorption-type polarizing plate, the rotation of the polarization axis of P-polarized light is controlled to approximately 0 ° to 90 ° by a liquid crystal panel using a TN type liquid crystal.

On the other hand, the reflective polarizers 30, 32, and 34 are controlled so that S-polarized light is mainly transmitted and P-polarized light is mainly reflected. As a result, the light transmitted through the reflective polarizers 30, 32, and 34 becomes light whose light intensity is modulated for each pixel by an image signal, and enters the prism 26.

In the conventional projection type display device, an absorption type polarizing plate mainly transmitting one polarization axis component and mainly absorbing the other polarization axis component is provided on the emission side. The absorbed P-polarized light was converted to heat, and heat was generated. In the present invention, although the film is the same as the absorption type polarizing plate, the reflected polarized light reflects the light of the other polarization axis component. Since the plate is used, the light absorption is small and the generation of heat is suppressed. This reflection type polarizing plate is composed of a multilayer structure film as described later in detail.

The transmission axis and absorption axis of the absorption type polarizing plate provided on the incident side may be set such that transmission is S-polarized light and absorption is P-polarized light. Further, it goes without saying that the transmission axis and the reflection axis of the exit-side reflection polarizing plate may be set so that transmission is P-polarized light and absorption is S-polarized light. Further, the liquid crystal of the liquid crystal panel does not have to be a liquid crystal having a twisted alignment such as a TN type, and may be a liquid crystal having a horizontal alignment or a vertical alignment.

Further, the cross dichroic prism 2
Reference numeral 6 has a function as color light combining means for combining three color lights to form a color image. The cross dichroic prism 26 is bonded with an adhesive so that the apex angles of the four right-angle prisms are matched, and along the inner surface to be bonded, a dielectric multilayer film that reflects red light and a blue light are formed. The reflecting dielectric multilayer film is formed in an X shape. The three color light beams are combined on the same optical axis by these dielectric multilayer films to form light representing a color image. The projection lens 27 has a function as a projection optical system for enlarging and projecting the light representing the synthesized color image on the screen 28.

In the projection type display device described above, a liquid crystal light valve of a type in which a light beam (S-polarized light or P-polarized light) having a specific polarization direction is incident and light modulated is used as the light modulating means. . Therefore, about half of the luminous flux transmitted through the liquid crystal panel is absorbed by the absorption type polarizing means provided on the emission side of the liquid crystal panel and converted into heat. As a result, there has been a problem that the light use efficiency is low and the incident side polarizing means generates heat.

However, in the projection display device of the present invention, as described above, the reflective polarizers 30, 32, and 34 mainly transmit light of one of the two types of polarization axes. On the other hand, light having the other transmission axis component is mainly reflected, so that problems such as poor light utilization efficiency due to light absorption and heat generation of the reflective polarizing plate are greatly improved. Further, as described later, since the reflective polarizing plate is a film having a multilayer structure stretched and formed, it is sufficient to replace the conventional absorption-type polarizing plate, and the optical system does not increase in size. Further, since the heat generation is drastically reduced, the cooling mechanism can be simplified, for example, it is not necessary to eliminate the cooling means or take special measures to increase the cooling efficiency of the cooling means. Further, conventionally, the absorption type polarizing plate generates a large amount of heat, so that the absorption type polarizing plate is separated from the liquid crystal panel and held.However, in the present invention, since the reflection polarizing plate generates little heat, the multilayer structure film is used for the liquid crystal panel. It can be adhered or attached to the outer surface of the light incident side substrate, and it is not necessary to provide a holding member for the reflective polarizing plate.

According to the configuration of the present invention, the light reflected by the reflective polarizers 30, 32, and 34 reaches the reflector 12 of the light source 10 via a mirror or the like, and is reflected there again. . The light reflected by the reflective polarizer is re-reflected by the reflective reflector 12, causing a slight shift in the optical path. Therefore, when the light is again incident on the liquid crystal panel, the light is incident on a region of the liquid crystal panel different from the first one, that is, the light in the direction of the polarization axis which is transmitted by the liquid crystal panel through the reflective polarizing plate someday.

As described above, according to the present invention, the amount of light transmitted through the exit-side reflective polarizer in the liquid crystal light valve can be increased as compared with the conventional case, and the efficiency of use of light from the light source can be increased as compared with the conventional case.

In the above embodiment, the absorption-type polarizing plates 29, 31, and 33 are provided on the incident side. However, the absorption-type polarizing hand plate on the incidence side mainly transmits light of one polarization axis component. , Can be replaced with a reflection polarization means that mainly reflects the light of the other polarization axis component that is substantially orthogonal to this. In this case, the light reflected from the incident-side reflective polarizer is emitted from the light source 1.
It returns to the 0 side, where it is re-reflected and light is again available at the liquid crystal light valve. In addition, since the light of the polarization axis component which has been absorbed in the past is reflected, the problem of heat generation of the incident-side polarization means is also solved.

Further, an absorption type polarizing plate may be provided on the exit side of the reflecting polarizing plate, that is, between the projection lens and the reflecting polarizing plate. In that case, the absorption-type polarizing plate is arranged such that the transmission axis of the absorption-type polarizing plate and the polarization axis direction of the light mainly transmitted by the reflection polarizing plate substantially coincide with each other. By doing so, even when the degree of polarization of the reflective polarizer is not sufficient, it is possible to absorb excess light by the absorption polarizer, thereby realizing a projected image with good contrast characteristics. Further, in the present invention, the reflected light from the reflective polarizing plate is reflected by the light source and returned to the light valve side. In this case, it is necessary to employ the following configuration as the configuration of the light source section. . That is, (1) the reflector of the light source unit has a parabolic reflecting mirror that reflects the light returned from the separating means and makes it substantially parallel light and emits the light, or (2) returns from the separating means. It is preferable to have a reflecting mirror such as a spherical reflector that reflects the reflected light, and a condensing unit such as a condenser lens that converts the light from the reflecting mirror into substantially parallel light and emits the light.

It should be noted that the present invention is not limited to the above-described examples and embodiments, but can be implemented in various modes without departing from the gist thereof.
For example, the following modifications are possible.

For example, when the present invention is applied to a projection display device that projects a black-and-white image, the device shown in FIG.
One liquid crystal panel and a pair of polarizing means are sufficient, and the color light separating means for separating light beams into three colors and the color light combining means for combining light beams of three colors can be omitted. When a color filter that transmits three primary color lights is arranged on the inner surface of one liquid crystal panel and color display is performed by a single liquid crystal panel, 1
A color image can be displayed with one liquid crystal panel and a pair of polarizing means.

In the embodiment, the incident-side polarizing means and the outgoing-side polarizing means are adhered to the outer surfaces of the respective substrates of the respective liquid crystal panels. However, both or one of them may be arranged separately from the liquid crystal panel. I do not care. In that case, a holding member for holding the polarizing means is separately required. In addition, even if it arrange | positions at a distance, the polarizing means must be arrange | positioned so that light may enter from the perpendicular direction to the incidence surface of a polarizing means.

Further, an integrator lens is disposed between the light source 10 and the first dichroic mirror 13 to convert light from the light source into uniform illumination light. May be used efficiently.

Also, of the random light from the light source 10,
The polarization converter (see FIG. 4 and its description, which will be described later) converts the light component of the reflection axis of the incident-side polarizing plate into a transmission axis component and emits the light as light of one polarization axis component. The light source 10 is disposed between the light source 10 and the dichroic mirror 13.
May be arranged so that the polarization axes of the lights from the light sources are aligned. However, since the polarization converter cannot completely convert the light source light into one polarization axis component, the light component that could not be converted is reflected by the incident-side absorption polarizing plate.

In this case, an image can be formed without providing an absorption type polarizing plate on the incident side.

Further, the order and method of separating the color light and the optical path of the synthesis in the embodiment are not limited to those described above. For example, the color light passing through the light guiding means 22 may be red light. In addition, any of a dichroic mirror and a dichroic prism may be used as the color light separating / combining means.

Even in the case of the above-mentioned modification, the above-mentioned multi-layered film having the function of mainly transmitting one polarization axis component and mainly reflecting the other polarization axis component is provided in the emission type. Such effects can be obtained.

(Explanation of Reflective Polarizing Plates) Next, the specific structure of the reflective polarizing plates 30, 32, and 34 (and the absorption polarizing plates 29, 31, and 33) used in this embodiment will be described with reference to FIGS. This will be described with reference to FIG. The reflective polarizing plate of the present embodiment,
This is a stretch-formed multilayer structure film having a function of mainly transmitting light of one polarization axis component and mainly reflecting light of the other polarization axis component. FIG. 5 is a view for explaining transmission / reflection of a polarization axis component of light in a liquid crystal light valve in a case where a film having a multilayer structure is provided on an emission side of a liquid crystal panel and an absorption type polarizing plate is provided on an emission side of the liquid crystal panel. is there. FIG. 6 shows FIG.
FIG. 2 is a configuration diagram showing a multilayer structure film as a reflective polarizing plate used in.

In FIG. 5, light from the light source side is provided as incident lights 501 and 502. The incident light includes light of an S-polarization axis component and a P-polarization axis component that are substantially orthogonal to each other. However, in the case where a polarization converter is inserted on the light source side, for example, the light of the S-polarization axis component of the light from the light source is converted into the light of the P-polarization axis component, and the light is emitted in alignment with the P-polarization light. ,
The ratio of the light incident on the incident side polarizing plate is almost the light of the P-polarization axis component, and the light of the S-polarization axis component is slight.

Numeral 503 denotes an absorption type polarizing plate which mainly transmits, for example, P-polarized component light of incident light, but mainly absorbs S-polarized light. The P-polarized light 501 transmitted through the absorption polarizer 503 enters the liquid crystal panel 504. The liquid crystal panel 504 uses TN type liquid crystal, and light (P-polarized light) incident on a pixel to which no voltage is applied to the liquid crystal (on the left side of the dotted line in FIG. 5) has its polarization axis rotated by approximately 90 °. The light is emitted as S-polarized light 509. On the other hand, the light (P) incident on a pixel (right side from the dotted line in FIG. 5) where a saturation voltage is applied to the liquid crystal
The polarized light is emitted as the light 508 of the polarization axis component as it is.

Reference numeral 505 denotes a reflective polarizing plate which mainly transmits, for example, light of a P-polarized light axis component of incident light, but mainly reflects light of an S-polarized light axis component. When the liquid crystal light valve is used in the normally white mode, the polarizing plate 505 is used.
Is set to the S polarization axis, and the liquid crystal panel
The light 509 emitted as polarized light is transmitted as it is. On the other hand, the light 508 emitted from the liquid crystal panel 504 as P-polarized light is reflected by the reflective polarizing plate 505, and passes through the liquid crystal layer and the reflective polarizing plate 503 again. Then, the light is re-reflected by the reflector 510 and the like and returns to the absorption polarizer 503. Since the light path of the re-reflected light is slightly shifted, a part of the light is incident on the pixel (left side from the dotted line in the figure) to which no voltage is applied to the liquid crystal, and the polarization axis is rotated by about 90 ° to make the S-polarized light. The light is emitted as 509 and can be transmitted through the reflective polarizing plate 505.

In the liquid crystal panel 504, by controlling the amount of rotation of the polarization axis of the incident light for each pixel, the reflection polarizing plate 5 is controlled.
The amount of light transmitted through the pixel 05 is controlled for each pixel, and an image is formed.

On the other hand, the S-polarized light 502 is
Absorbed at 3.

As described above, the absorption-type polarizing plate 503 on the incident side is made to mainly transmit one polarization axis component and to mainly reflect the other polarization axis component, similarly to the emission side. A reflective polarizing plate may be used. Then, the S-polarized light 502 is reflected by the light source side instead of being absorbed by the absorption type polarizing plate as shown in the figure. The details of such a reflective polarizer used in the present invention are disclosed in Japanese Patent Application Laid-Open No. 9-506985 as "reflective polarizer".

FIG. 6 shows details of the reflective polarizing plate made of the multilayer structure film. The multilayer structure film is composed of a laminate of films formed by stretching a polymer, and has two different types of layers 601 (layer A) and 602 (layer B).
Have a multilayer structure alternately stacked in the Z-axis direction.
For example, a layer obtained by stretching polyethylene naphthalate (PEN) is used for the A layer 601 of the reflective polarizing plate, and a copolyester (co) of naphsalen dicarboxylic acid and terephthalic acid is used for the B layer 602.
PEN; copolyester of napthalene dicarboxylic a
cid and terephthallic or isothalic acid). Of course, the material of the reflective polarizing plate used in the present invention is not limited to this, and the material can be appropriately selected.

The refractive index (n _AX ) of the A layer 601 in the X-axis direction
And the refractive index (n _AY ) in the Y-axis direction are different from each other. on the other hand,
The refractive index in the X-axis direction (n _BX ) of the B layer 602 is set to be substantially equal to the refractive index in the Y-axis direction (n _BY ). Further, the refractive index (n _AY ) of the A layer 601 in the Y-axis direction and the refractive index (n _BY ) of the B layer 602 in the Y-axis direction are set to be substantially equal. In other words, to summarize this, (n _AX ) {(n _AY ), (n _BX )} (n _BY )
≒ (n _AY ).

As described above, the linearly polarized light in the Y-axis direction (P-polarized light in the embodiment) of the light incident on the multilayer structure film is in a state in which there is substantially no difference in the refractive index between the laminations. Therefore, this multilayer structure film is transmitted as it is with its polarization axis.

[0063] On the other hand, when the Z-axis direction of the layer thickness of _t A of the A layer 601, the thickness in the Z-axis direction of the B layer 602 and _{t B,} the wavelength of the incident light _{λ, t A · n AX +} t _B · _{n BX} ≒
By setting so as to be λ / 2 (1), linearly polarized light in the X-axis direction (S-polarized light in the embodiment) out of the light having the wavelength λ can be used for the adjacent A layer and B layer. At the interface, the light is reflected as polarized light in the X-axis direction.
By changing the layer thicknesses t _A and t _B of the A layer 601 and the B layer 602 variously and laminating them, the transmission wavelength band can be widened so that the above equation (1) is satisfied over a wide range of all visible light wavelengths. For example, white light of linearly polarized light (S-polarized light) in the X-axis direction can be reflected. Incidentally, the multilayer structure film may be formed by sequentially laminating layers having different thicknesses,
It may be formed by laminating a plurality of laminated bodies in which several layers having the same thickness are laminated. Also,
The expression indicated by the symbol ≒ is more preferable if it is possible to obtain completely equal refractive indices.

When the polarization accuracy of the reflective polarizing plate of the above multilayer structure film is low, a plurality of reflective polarizing plates are arranged on the optical axis, and a plurality of reflective polarizing plates are formed to improve the polarizing accuracy. May be.

Here, the wavelength selective transmission characteristics of the reflective polarizing plate need not be common to all three liquid crystal light valves, and are set so as to selectively transmit the color light modulated by each light valve. You may do so.
That is, as shown in FIG. 7, the wavelength selective transmission characteristic 510 of the reflective polarizing plate 30 of the light valve for red light is such that light in a red wavelength band (a band of about 600 nm to 700 nm) is selectively transmitted. And the wavelength selective transmission characteristic 520 of the reflective polarizing plate 32 of the light valve for green light is set so as to selectively transmit light in a green wavelength band (a band of about 500 to 600 nm). The wavelength selective transmission characteristic 530 of the reflective polarizing plate 34 of the light valve may be set so as to selectively transmit light in a blue wavelength band (a band of about 400 to 500 nm). in this case,
The reflective polarizer has a function similar to that of the interference color filter, and light having a wavelength outside the wavelength band is reflected without being transmitted. Therefore, even if the color separation characteristics of the dichroic mirror are not sufficient, color light with high color purity can be made incident on the three light valves, and the combined light obtained by combining the light modulated by the three light valves has color purity. , It is possible to obtain a projection display device with high color reproducibility. Specifically, A in FIG.
What is necessary is just to laminate | stack and laminate | stack the 2nd multilayer structure film which made the setting of the film thickness and the refractive index in the layer 601 and the B layer 602 different from the said setting. This second multilayer structure film sets the transmission wavelength band of the linearly polarized light in the Y-axis direction (P-polarized light in the above example) to be a part of the visible light wavelength band.

That is, (n _AX ) ≠ (n _AY ), (n
( _BY ) 設定 (n _BX ) (n _AX ), the refractive index is set, and t _A · n _AY + t _B · n _BY ≒ λ / 2 (2)
The film thickness is set so that Here, the wavelength λ is set to a wavelength band that does not pass through the reflective polarizing means. For example, in order for the polarizing means 30 of the light valve for red light to have the wavelength selective transmission characteristic 510, the wavelength band excluding the red wavelength band is set to be λ in the above equation (2). The polarization means 32 of the light valve for green light and the polarization means 34 of the light valve for blue light also have wavelength selective transmission characteristics 5.
A wavelength band excluding 20 and the wavelength selective transmission characteristic 530 may be set as λ. In this manner, when the film thickness of the second multilayer structure film is set to be different between the respective light valves according to the wavelength band in which each of the light valves is reflected, the P-polarized light having the wavelength of the color light modulated by each light valve is set. Light will be transmitted. Most of the S-polarized light is reflected on the first multilayer structure film described above. Further, the second multilayer structure film may be arranged on either the entrance side or the exit side of the first multilayer structure film.

If the wavelength selective transmission band of each polarizing means is made narrower than the wavelength separation band of the light transmitted or reflected by each dichroic mirror, color light having extremely high color purity can be incident on the liquid crystal panel. Therefore, it is possible to obtain a projection display device with high color reproducibility.

On the other hand, the wavelength selective transmission band of each reflective polarizing plate may be equal to or wider than the wavelength separation band of light transmitted or reflected by each dichroic mirror. In particular, a dichroic mirror cannot completely separate wavelengths, and the separated three color lights include wavelength components different from the original color light components. However, if the reflective polarizing plate of the present invention has a wavelength selective transmission characteristic equal to or broader than the wavelength separation characteristic of the dichroic mirror, the wavelength band separated by the dichroic mirror passes through the reflection polarizing plate as it is. However, only the wavelength band component that is distant from the wavelength of the original color light can be reflected by the reflective polarizing plate to be opaque. As a result, it is possible to obtain a projection display device in which the light use efficiency is improved while securing a certain degree of color reproducibility.

In the above description, the transmission axis and the reflection axis of the reflection polarizing plate provided on the emission side may be set such that transmission is S-polarized light and reflection is P-polarized light. Further, it goes without saying that the setting of the transmission axis and the absorption axis (or the reflection axis) of the incident-side polarizing plate may be reversed.

The configuration of the reflective polarizer described above is applied to each of the following embodiments in the same manner.

[Second Embodiment] Next, a second embodiment will be described with reference to the drawings. FIG. 2 is a schematic configuration diagram illustrating a main part of the projection display apparatus according to the present embodiment. The basic configuration of the projection display apparatus of this embodiment is the same as that of the first embodiment, but an illumination optical system 103 including a light source 100 and a uniform illumination optical system 101, and condenser lenses 118 and 130. ,
131 from the first embodiment. In addition, in the part which is not described in this embodiment, the first
This is the same as described in the embodiment.

The light beam from the illumination optical system 103 is separated into red light (R) and green / blue light by a first dichroic mirror 113 that transmits red light and reflects green / blue light. The green / blue light reflected by the first dichroic mirror 113 is separated into green light and blue light by the second dichroic mirror 114 that reflects the green light (G) and transmits the blue light (B). . The color light separating means is constituted by two dichroic mirrors, and the separated three color lights are supplied to the respective liquid crystal light valves 123, 1
24, 125.

The red light transmitted through the first dichroic mirror 113 is reflected by the mirror 117, is incident on the condensing lens 131 composed of a plano-convex lens, is converted into parallel light, and is incident on the liquid crystal light valve 123. The green light reflected by the second dichroic mirror 114 is
The light is collimated by a condenser lens 130 composed of a plano-convex lens similar to 131 and is incident on a liquid crystal light valve 124. Further, the blue light transmitted through the second dichroic mirror 114 is converted into parallel light by a condensing lens 118 formed of a plano-convex lens, reflected by the mirror 115, becomes parallel light again via a relay lens 119, and becomes a parallel light again.
And is incident on the blue liquid crystal light valve 125 in a parallel light state. The relay lens 119 is
In the optical path length from the light source 103 to each of the liquid crystal light valves, only the optical path length of the blue light is longer than that of the red light and the green light to prevent light loss. The focal length of the relay lens 119 is set substantially equal to the optical path length from the exit point of the condenser lens 118 to the liquid crystal light valve 125. Thereby, the distance from the light source of each color light to the light valve is substantially equivalent.

Liquid crystal light valves 123, 124, 125
Comprises an incident-side polarizing plate, a liquid crystal panel, and an output-side reflective polarizing plate having the same configuration and the same function as those of the first embodiment. The structure of the liquid crystal panel is similar to that of the first embodiment.
It is composed of an active matrix transmission type liquid crystal panel having a T and a pixel electrode connected thereto. The operation of transmitting / reflecting light in the liquid crystal light valve is as described with reference to FIG. 5, and is the same as in the first embodiment.

Further, similarly to the first embodiment, the incident-side polarizing plate may be the above-mentioned conventional absorption-type polarizing plate, or may be a reflective polarizing plate similarly to the exit-side.

The reflection polarizing plate provided on the output side mainly transmits light of one polarization axis component (for example, P-polarized light) and reflects light of the other polarization axis component (for example, S-polarized light). It is composed of the multilayer structure film described in the first embodiment (see FIG. 6). In each liquid crystal light valve, the multilayer structure film described with reference to FIG.
The liquid crystal panel is in close contact with or attached to the outer surfaces of a pair of substrates.

The three liquid crystal light valves 123, 124,
The color lights modulated by the respective lenses 125 are combined on the same optical axis by the same cross dichroic prism 126 as in the first embodiment, and guided to the projection lens 127. The combined color light projected by the projection lens 127 is imaged on the screen 128 and displayed as an image.

In the above description, the transmission axis and the absorption axis of the absorption polarizer on the incident side may be set such that transmission is the S polarization axis and absorption is the P polarization axis. Further, it goes without saying that the setting of the transmission axis and the absorption axis (or the reflection axis) of the reflection polarizer on the emission side may be reversed. Further, the reflective polarizer used in the present invention may be set to have the wavelength selective transmission characteristics as described in the first embodiment. The configuration and operation of the reflective polarizing plate in that case are the same as in the first embodiment.

As described above, according to the present embodiment, at least the emission side polarization means of the liquid crystal light valve transmits light of one polarization axis component of the two types of polarization axes, but transmits the other transmission axis component. Has a function of reflecting light, so that the problem of heat generation in the reflective polarizing plate on the emission side is greatly improved. If the incident-side polarizing plate is a reflective polarizing plate similar to the emitting-side polarizing means, as described in the first embodiment, both the heat generation and the problem in the emitting-side polarizing means are improved, and the light use efficiency is further improved. Further, since such a polarizing means is a film having a multilayer structure as described in FIG. 6, it is sufficient to replace a conventional polarizing plate, and the optical system does not become large. In addition, heat generation is drastically reduced, so there is no need for cooling means.
Alternatively, the cooling mechanism can be simplified, for example, without having to take special measures to increase the cooling efficiency of the cooling means. Furthermore, with such a reflective polarizer, the reflective polarizer can be closely attached or attached to the outer surface of the substrate of the liquid crystal panel.

The uniform illumination optical system 101 is a first illumination optical system which is arranged in parallel on a plane perpendicular to the central axis 102 of the illumination optical system.
And a second lens plate 133. The first lens plate 132 has a configuration in which a plurality of rectangular lenses are arranged in a matrix, and the second lens plate 133 has a configuration in which a plurality of rectangular lenses are arranged in a matrix. Since the shape of each rectangular lens of the first lens plate 132 is similar to the shape of the liquid crystal panel, the image of each rectangular lens of the first lens plate 132 is
The light is superimposed on the liquid crystal panel by the respective rectangular lenses of the lens plate 133. In the first place, the luminous flux from the light source 100 has a high light intensity near the center and a low intensity around the periphery. Since the light of each part is condensed and further irradiated by the rectangular lens of the second lens plate so as to be superimposed on the liquid crystal panel, the brightness becomes uniform within the screen.

As described above, in the present embodiment, the multi-layered film described in FIG. 6 is disposed as the polarizing means of the liquid crystal light valves 123, 124, and 125. Uniform illumination optical system 103
Since light of uniform brightness is irradiated, light of one polarization axis component is transmitted, and light of the other polarization axis component is reflected,
A light beam having one polarization axis component, in which the in-plane light intensity distribution is uniform, enters the liquid crystal panel. In addition, since the light from the light source is collimated by the condenser lenses 118, 130, and 131, the light is incident substantially perpendicularly to the incident surface of the incident-side polarizing plate (and the exit-side reflective polarizing plate). Even if light is reflected by the reflective polarizing plate, it can be reflected to the uniform illumination optical system 103 along the optical axis. The light source is a light source lamp 11
A reflector 112 that emits the light emitted from the light source 1 and the reflected light reflected from the polarizing means to the first lens plate as substantially parallel light.
Having. Therefore, as described in the first embodiment,
The reflected light is re-reflected by the reflector 112 on the light source side, and re-enters the incident-side polarizing plates of the liquid crystal light valves 123, 124, and 125 again. Further, an absorption type polarizing plate may be provided on the emission side of the reflective polarizing plate, that is, between the projection lens and the reflective polarizing plate. In that case, the absorption-type polarizing plate is arranged such that the transmission axis of the absorption-type polarizing plate and the polarization axis direction of the light mainly transmitted by the reflection polarizing plate substantially coincide with each other. By doing so, even when the degree of polarization of the reflective polarizer is not sufficient, it is possible to absorb excess light by the absorption polarizer, thereby realizing a projected image with good contrast characteristics.

Further, in the present invention, the reflected light from the reflective polarizing plate is reflected by the light source and returned to the light valve side. In this case, the following configuration may be adopted as the configuration of the light source section. is necessary. That is, (1) the reflector of the light source unit has a parabolic reflecting mirror that reflects the light returned from the separating means and makes it substantially parallel light and emits the light, or (2) returns from the separating means. It is preferable to have a reflecting mirror such as a spherical reflector that reflects the reflected light, and a condensing unit such as a condenser lens that converts the light from the reflecting mirror into substantially parallel light and emits the light.

The present invention is not limited to the above examples and embodiments, but can be implemented in various modes without departing from the gist of the invention.
For example, the following modifications are possible.

For example, when the present invention is applied to a projection display device that projects a black-and-white image, one liquid crystal panel and a pair of polarizing means are sufficient, and a color light separating means for separating a light beam into three colors is provided. A color light synthesizing means for synthesizing a color light beam can be omitted. When a color filter that transmits the three primary colors is disposed on the inner surface of one liquid crystal panel and color display is performed by a single liquid crystal panel, a color image is displayed by one liquid crystal panel and a pair of polarizing means. be able to.

Further, of the random light from the light source, a polarization converter (see FIG. 4 and its description, which will be described later) that converts the light component of the reflection axis of the incident side polarization means into the transmission axis component is provided.
It may be arranged between the light source 100 and the first dichroic mirror 113 so that the polarization axes of the light from the light source are aligned. However, since the polarization converter cannot completely convert the light source light into one polarization axis component, the light component that could not be converted is absorbed by the incident-side polarizing plate.

The separation order / method of the color light and the optical path of the combination in the embodiment are not limited to those described above. For example, the color light passing through the light guide means may be red light.

Third Embodiment Next, a third embodiment will be described with reference to the drawings. FIG. 3 is a schematic configuration diagram illustrating a main part of the projection display apparatus according to the present embodiment. The basic configuration of the projection display apparatus of the present embodiment is the same as that of the first embodiment, except that the projection display apparatus includes an illumination optical system 203 including a light source unit 200 and a polarized illumination optical system 201. I have. In addition, in the part which is not described in this embodiment, the first
This is the same as described in the embodiment.

This projection type display device comprises a light source 200, dichroic mirrors 213, 214, and a reflection mirror 21.
5, 216, 217, an entrance lens 218, a relay lens 219, an exit lens 220, three liquid crystal light valves 223, 224, 225, a cross dichroic prism 226, and a projection lens 227. Note that the input lens 218, the relay lens 219, the output lens 220, and the reflection mirrors 215 and 216
Is composed.

In FIG. 3, the light source unit 200 has the same configuration as that of the first embodiment. Dichroic mirror 21
3, 214, as in the first embodiment, has a function as a color light separation unit that separates a light beam from a light source into three color lights of red, blue, and green. The light beams from the light sources 200 are separated into red light (R) and green / blue light by a first dichroic mirror 213 that transmits red light and reflects green / blue light. The green and blue lights reflected by the first dichroic mirror 213 are separated into green light and blue light by the second dichroic mirror 214 that reflects the green light (G) and transmits the blue light (B). . The color light separating means is constituted by two dichroic mirrors, and the separated three color lights are respectively supplied to the liquid crystal light valves 223, 2
24, 225.

In this embodiment, the optical path length of blue light is 3
It is the longest of the two colored lights. Therefore, for blue light, after the dichroic mirror 14, the incident lens 2
18, a relay lens system including a relay lens system including a relay lens 219 and an emission lens 220 is provided. That is, after transmitting the blue light through the green light reflecting dichroic mirror 214, first, the incident lens 2
18 and the reflection mirror 215, the relay lens 219
It is led to. Further, the light is reflected by the reflection mirror 216, guided to the emission lens 220, and made incident on the liquid crystal light valve 225 for blue light.

The liquid crystal light valves 223, 224
Reference numeral 225 includes an incident-side polarizing plate, a liquid crystal panel, and an output-side reflective polarizing plate having the same configuration and the same function as those of the first embodiment. As in the first embodiment, the structure of the liquid crystal panel is constituted by an active matrix transmission type liquid crystal panel having a TFT and a pixel electrode connected thereto in each pixel. The effect of light transmission / reflection in the liquid crystal light valve is shown in FIG.
And is the same as that of the first embodiment. The incident-side polarizing plate is a polarizing plate that transmits light of one polarization axis component (for example, P-polarized light) and absorbs light of the other polarization axis component (for example, S-polarized light). Further, the reflection polarizer on the emission side transmits the light of the other polarization axis component (for example, S-polarized light) and transmits the light of one polarization axis component (for example, P-polarized light) as a reflection polarizer. It consists of the multilayer structure film described in the examples (see FIG. 6). Further, in each liquid crystal light valve, the multilayer structure film described in FIG. 6, which becomes the incident side polarizing plate and the outgoing side polarizing polarizer, is adhered or attached to the outer surfaces of a pair of substrates constituting the liquid crystal panel. I have.

The three liquid crystal light valves 223, 224,
The color lights modulated by 225 are combined on the same optical axis by the same cross dichroic prism 226 as in the first embodiment, and guided to the projection lens 227. The combined color light projected by the projection lens 227 is imaged on a screen 228 and displayed as an image.

In the above description, the transmission axis and the absorption axis of the incident-side polarizing plate may be set such that transmission is the S-polarization axis and reflection is the P-polarization axis. Further, it goes without saying that the setting of the transmission axis and the reflection axis of the exit-side polarizing plate may be reversed. Further, the reflective polarizer used in the present invention may be set to have the wavelength selective transmission characteristics as described in the first embodiment. The configuration and operation of the polarizing means in that case are the same as in the first embodiment.

This embodiment is different from the first and second embodiments in that an illumination optical system 203 including a polarized illumination optical system 201 is provided. The polarized illumination optical system 201 converts the randomly polarized light emitted from the light source unit 200 into one type of linearly polarized light having almost the same polarization direction and emits it.

Hereinafter, the illumination optical system 203 will be described in detail. The light source unit 200 includes a lamp and a reflector having a parabolic shape. Light emitted from the lamp is reflected in one direction by the reflector, enters a polarization illumination optical system 201 as a substantially parallel light flux. The optical axis of the light source light of the light source unit 200 is shifted parallel to the output optical axis of the illumination optical system 203 by a certain distance. In addition,
The reflector may have a spherical shape, and a condenser lens that condenses the reflected light from the reflector and converts the reflected light into substantially parallel light may be disposed on a light source side of a first optical element 232 described later.

The polarized illumination optical system 201 has a first optical element 232 and a second optical element 233. The first optical element 232 is formed of a lens plate, on which a plurality of rectangular lenses are formed in a matrix. The optical axis of the light source unit 200 is arranged so as to coincide with the central axis of the first optical element 232. In the first optical element 232, similarly to the first lens plate 132 in FIG. 2, each rectangular lens has a shape similar to a liquid crystal panel. Next, the second optical element 233
Are a condenser lens array 234, a polarizing beam splitter array 235, a wave plate 236, and an emission side lens 237.
Consists of A plurality of rectangular lenses are formed in the condenser lens array 234, similarly to the second lens plate 133 in FIG. As in the second embodiment, the rectangular lens of the second lens plate has a function of superimposing and irradiating the image of each rectangular lens of the first optical element onto the liquid crystal panel. The liquid crystal panel can be illuminated with uniform brightness.

Next, the polarization beam splitter array 235
Functions as a polarization converter that converts light of one polarization axis (for example, S-polarized light) into light of the other polarization axis (for example, P-polarized light), and emits light aligned with one of the polarization axes (in this case, P-polarized light). Having.

FIG. 4 shows details of the polarization beam splitter array 235.

FIG. 14A shows a first configuration example. The polarization beam splitter array 235 includes a polarization separating unit 320 formed in a plate shape by bonding a plurality of light-transmissive members (glass or the like) 322 having a parallelogram cross section and bonding parallel surfaces with adhesives 325a and 325b. Have. Since the light source unit 200 is a randomly polarized light, the light (including the P-polarized light and the S-polarized light) condensed by the condensing lens 234 disposed in front of the polarization beam splitter array 235 is first transmitted to the light transmitting unit 342.
Incident on the optical member formed of the light shielding portion 341. The light transmitted through the light transmitting portion 342 enters from each of the incident surfaces 327 of each of the light transmitting members 322. However, the incident light is condensed on the light transmitting portion 342 by the condensing lens 234 disposed immediately before. Since the light is blocked by the light-shielding portion on the incident surface 327 facing the light-shielding portion 341, no light is incident. Light shielding part 341
Light is slightly incident on the light source unit 200 because the light shielding unit has a reflecting mirror function.
Is reflected to the reflector, where it is reflected and returns again.

The P-polarized light component of the incident S-polarized light and P-polarized light is reflected by the polarization splitting film 331a. This film is an interference multilayer film formed by vapor deposition on one surface of the translucent member 322. After this film is formed, each translucent member is bonded to the adhesive 3
25. The component of S-polarized light transmitted through the polarization separation film is converted into a polarization conversion film (1/4 wavelength plate) 381 (2 in FIG. 3).
36), the polarization axis of the S-polarized light is rotated by about 90 ° and converted to P-polarized light. On the other hand, the reflected P-polarized light is reflected by the reflection film 332b. Therefore, the light substantially aligned with the P-polarized light is reflected from the polarization beam splitter array toward the optical axis direction of the polarization illumination optical system 201.

With the above configuration, the light emitted from the polarizing beam splitter array is emitted in the direction of the optical axis of the polarized light illumination optical system 201, in which the randomly polarized light of the light source is aligned with the P-polarized light. Note that, in reality, the polarization conversion film 381 can convert most S-polarized light components to P-polarized light, but light of a component other than P-polarized light (S-polarized light component) is also emitted without being completely converted. .

FIG. 4B shows a second configuration example. As shown, the polarization beam splitter array 23
5 is a translucent member (glass or the like) 32 whose cross section is a parallelogram.
2 has a polarization separating means 320 formed in a plate shape by bonding a plurality of parallel surfaces with an adhesive 325. Since the light source unit 200 is a randomly polarized light, the light (including the P-polarized light and the S-polarized light) condensed by the condensing lens 234 is transmitted to each of the incident surfaces 3 of the translucent members 322.
Light enters from 27. The incident S-polarized light and P-polarized light components are reflected by the reflection film 332. The reflected P-polarized light and S-polarized light components are separated by the polarization separation film 331 into the P-polarized light and the S-polarized light.
Separated into polarized light. The polarization separation film 331 is a film that reflects S-polarized light and transmits P-polarized light. Therefore, the P-polarized light transmitted through the polarization separation film 331 is reflected and emitted by the reflection film 332b. Further, the light exit surface 3 of the light transmitting member 327
At 26, a wave plate 381 (236 in FIG. 3), which is a quarter wave plate, is disposed every other translucent member, and the S-polarized light is rotated by approximately 90 °, converted into P-polarized light, and emitted. . In addition,
In the second configuration example, the light is condensed on the incident surface 327 by the condensing lens 234, but a small amount of light also enters incident surfaces other than the incident surface 327. The light is emitted as S-polarized light without polarization conversion.

As described in connection with the above-described two configuration examples, the polarization beam splitter array transmits the random polarized light of the light source almost in the direction of the optical axis of the polarized illumination optical system 201.
The light can be emitted in alignment with the polarized light. The emitted light beam is collimated by the emission side lens 237 and emitted toward the dichroic mirror 213.

In reality, as described above, most of the S-polarized light component can be converted to P-polarized light in the polarization conversion film 381, but the light of the S-polarized light component is also emitted without being completely converted. I have. Further, when light is incident on the incident surface of the translucent member on which the polarization conversion film 381 is not disposed, both the P-polarized light and the S-polarized light are reflected by the polarization separation film 331,
The light is reflected by the reflection film 332b and is emitted without the polarization axes being aligned.

In the first and second embodiments described above, as the incident-side polarizing plate of the liquid crystal light valve, light having one polarization axis (for example, P-polarized light) is mainly transmitted and the other polarization axis (for example, P-polarized light) is transmitted. Randomly polarized light (including both P-polarized light and S-polarized light) emitted from a light source is incident on an absorption polarizer that mainly absorbs light of, for example, S-polarized light, and thus is about half of the incident light. Is absorbed and may cause heat generation of the incident side polarizing plate.

However, in the present embodiment, most of the randomly polarized light from the light source can be aligned with the transmission axis of the incident side polarizing hand plate by the polarized light illumination optical system 201. , Most of the light from the light source is transmitted, and the remaining polarized light components, which have not been sufficiently converted in polarization, are absorbed by the incident-side polarizing plate.

By the way, the light reflected by the reflection polarizer on the emission side is re-reflected by the reflector of the light source, etc.
Part of the light further passes through the incident-side polarizing plate, and can be used as projection light.

As described above, according to this embodiment, at least the outgoing reflective polarizing plate of the liquid crystal light valve transmits light of one polarization axis component of the two types of polarization axes but transmits the other transmission axis. Since the component light has a function of reflecting light, the problem of heat generation in the reflective polarizing plate on the emission side is greatly improved. If the incident-side polarizing means is a reflective polarizing plate similar to the incident-side polarizing means, as described in the first embodiment, both the heat generation and the problem in the emitting-side polarizing means are improved, and the light use efficiency is further improved.

In this embodiment, since the light emitted from the light source is converted into the light in one direction of the polarization axis by the polarization converter, the image formation by the light valve can be performed even if the incident side polarizing plate is omitted. Is possible.

Further, since such a polarizing means is a film having a multilayer structure as described with reference to FIG. 6, it is sufficient to replace the conventional polarizing plate, and the optical system is not enlarged. Further, since the heat generation is drastically reduced, the cooling mechanism can be simplified, for example, eliminating the need for the cooling means or special measures for increasing the cooling efficiency of the cooling means. Furthermore, with such a reflective polarizing plate, the polarizing plate can be closely attached or attached to the outer surface of the substrate of the liquid crystal panel.

Further, an absorption type polarizing plate may be provided on the exit side of the reflecting polarizing plate, that is, between the projection lens and the reflecting polarizing plate. In that case, the absorption-type polarizing plate is arranged such that the transmission axis of the absorption-type polarizing plate and the polarization axis direction of the light mainly transmitted by the reflection polarizing plate substantially coincide with each other. By doing so, even when the degree of polarization of the reflective polarizer is not sufficient, it is possible to absorb excess light by the absorption polarizer, thereby realizing a projected image with good contrast characteristics.

In the above description, the transmission axis and the absorption axis of the incident side polarizing plate may be set such that transmission is the S polarization axis and absorption is the P polarization axis. Further, a configuration may be adopted in which the polarization axis emitted from the polarization converter is aligned with S-polarized light. It goes without saying that the setting of the transmission axis and the reflection axis of the exit-side reflective polarizing plate may be reversed. Further, the reflective polarizer used in the present invention may be set to have the wavelength selective transmission characteristics as described in the first embodiment. The configuration and operation of the polarizing means in that case are the same as in the first embodiment.

It should be noted that the present invention is not limited to the above Examples and Embodiments, but can be implemented in various modes without departing from the gist of the invention.
For example, the following modifications are possible.

For example, when the present invention is applied to a projection display device that projects a black-and-white image, one liquid crystal panel and a pair of polarizing means are sufficient, and a color light separating means for separating a light beam into three colors is provided. A color light synthesizing means for synthesizing a color light beam can be omitted. When a color filter that transmits the three primary colors is disposed on the inner surface of one liquid crystal panel and color display is performed by a single liquid crystal panel, a color image is displayed by one liquid crystal panel and a pair of polarizing means. be able to.

In the embodiment, the incident-side polarizing plate and the outgoing-side reflecting polarizing plate are attached to the outer surface of the substrate of each liquid crystal panel. However, both or one of them may be disposed apart from the liquid crystal panel. I do not care. In that case, a separate holding member for holding the polarizing plate or the reflective polarizing plate is required. Also,
The optical path for separating and synthesizing the color light in the embodiment is not limited to this. For example, the color light passing through the light guide 222 may be red light.

[Embodiment of Liquid Crystal Panel] An embodiment of a liquid crystal panel used in the liquid crystal light valves of the first to third embodiments will be described below with reference to the drawings. FIG. 10 is a sectional view of each liquid crystal panel, and FIG. 11A is a plan view of a light emission side substrate of each liquid crystal panel. FIG. 10 shows A in FIG.
It shows a cross-sectional view of -A '. A feature of this embodiment is that a lower light-shielding film 703 of a thin film transistor is formed on a light emission side substrate 701 of a liquid crystal panel.

In FIG. 10, each liquid crystal panel is provided between a pair of substrates of a light emitting side substrate 700 and a light incident side substrate 701.
A liquid crystal 702 such as a TN type is sandwiched. The liquid crystal is TN
Not only a mold, but also a memory type such as a horizontal alignment type, a vertical alignment type, a polymer dispersion type, and a ferroelectric can be used as appropriate. A light-shielding film 703 formed of a metal such as chromium or titanium is formed in a matrix on the inner surface of the light incident side substrate 701, and a first interlayer insulating film formed of silicon nitride or silicon oxide is formed thereon. Membrane 70
4 is formed on the entire surface, and a silicon layer made of polycrystalline silicon or amorphous silicon is formed thereon in an island shape. This silicon layer is to be a channel 707, a source 705, and a drain 706 later. A gate insulating film 708 made of a silicon oxide film is formed on the surface of the silicon layer by thermal oxidation, CVD, or the like, and a gate electrode 709 is formed facing the channel 707 thereon. The gate electrode 709 also serves as a scanning line formed in a matrix in a pixel region of the liquid crystal panel, and is formed of polycrystalline silicon, a metal such as aluminum or tantalum, or the like. When polycrystalline silicon is used, a high melting point metal may be laminated thereon.

In the figure, after a metal is used for the gate electrode 709 and an insulating film formed by anodic oxidation of the surface covers the gate electrode, impurity ions are formed on the silicon layer using the gate electrode and the anodic oxide film as a mask. Inject and sauce 7
05, the drain 706 is formed in a self-aligned manner. Note that an LDD structure can be obtained by forming a region having a lower impurity concentration than the source / drain in the silicon layer between the channel 707, the source 705, and the drain 706 in advance. As described above, a thin film transistor serving as a switching element is configured for each pixel.

Next, a second interlayer insulating film 710 made of silicon nitride, silicon oxide or the like is formed on the entire surface of the thin film transistor. Here contact hole 71
2 is formed, and a data signal line 711 made of a metal such as aluminum is formed to be connected to the source 705 via the contact hole 712. Next, a third interlayer insulating film 714 made of silicon nitride, silicon oxide, or the like is formed, and a contact hole 713 is formed in the second and third interlayer insulating films at the same time. And ITO
A pixel electrode 715 made of a transparent conductive film, such as, for example, is connected to the drain 706 via the contact hole 712. Although not shown, an alignment film is thereafter formed as the uppermost layer, and this film is subjected to a rubbing process.

On the other hand, a light-shielding film 717 made of a metal such as chromium or a black resin is formed on the inner surface of the light emitting side substrate 700. The light-shielding film 717 can be formed in a matrix shape inside the light-shielding film 703 of the light-emitting side substrate 701 in a plane. Further, a counter electrode 716 made of a transparent conductive film such as ITO is formed on the entire surface of the light-shielding film 703. Although not shown, an alignment film is thereafter formed as the uppermost layer, and this film is also subjected to a rubbing process.

In the liquid crystal panel, scanning lines 709 and data signal lines 711 are formed in a matrix, and each pixel has a gate electrode as a scanning line and a source 705 as a data signal line.
Is connected to a thin film transistor (hereinafter, referred to as TFT).
A pixel electrode 715 connected to the drain 706 of the FT. Each pixel applies an image signal from a data signal line to a pixel electrode 715 using a TFT as a switching element, applies a voltage to a liquid crystal layer 702 sandwiched between the pixel electrode 715 and a counter electrode 716, and adjusts the orientation of liquid crystal molecules according to the applied voltage. Control. Further, in each pixel, the silicon layer of the drain 706 is extended so that the voltage applied to the liquid crystal can be held even in the non-selection period in which the TFT is turned off, and the scanning line 709 (one A scanning line to which a selection potential is applied in the previous horizontal scanning period. The pixel is kept at a non-selection potential for one vertical scanning period from the time of selection of this pixel via a gate insulating film. A storage capacitor 718 is formed between the storage capacitor 718 and the non-selection potential. Note that the storage capacitor 718 is not formed by a drain silicon layer and a scanning line, but is provided with a new capacitor line arranged in parallel with the scanning line, and a pixel electrode 715 opposed to this via an interlayer insulating film.
May be formed.

In the above-described liquid crystal panel, when light is incident on the TFT, particularly the channel 707, the TFT leaks even in a non-conductive state (when not selected). Then, the accumulated charges are discharged through the TFT, and the voltage applied to the liquid crystal changes. In such a case, the contrast of the liquid crystal panel is greatly reduced. The first
In each of the light valves of the third to third embodiments, the case where the reflection polarizing plate is used on the emission side has been described. In this case, the exit-side polarizing plate transmits light of any one of the polarization axes (S-polarized light in the above embodiment), but transmits the other polarization axis (P in the above embodiment).
(Polarized light) is reflected. The reflective polarizer receives both the S-polarized light and the P-polarized light according to the voltage applied to the liquid crystal of each pixel, so that the amount of light reflected from the reflective polarizer increases. When this light enters the TFT, the characteristics of the liquid crystal panel deteriorate.

In this embodiment, a light-shielding film 717 is formed on the light-emitting side substrate so that reflected light from the light-emitting side reflective polarizing means does not enter the TFT. In addition, the TFT blocks light reflected from the light incident side from the light incident side.
And the data line 711 overlaps the TFT. Therefore, the TFT is shielded from both the light incident side and the light emitting side.

With the configuration of the liquid crystal panel as described above, the light-outgoing-side polarizing means of the liquid crystal panel in the liquid crystal light valve can be a reflective polarizing plate as described in each of the above embodiments.

FIG. 11B shows an equivalent circuit diagram of one pixel in the above liquid crystal panel. When the scanning period of the pixel arrives, the scanning line driver (not shown) supplies the scanning line 7.
The TFT is selected and turned on in accordance with the scanning signal supplied to the switch 09. On the other hand, an image signal to be written to the selected pixel is supplied from a data line side driver (not shown), and a voltage of the image signal is applied to the liquid crystal 702 and the storage capacitor 718 via the conductive TFT. Thereafter, when the TFT is deselected and becomes non-conductive, the capacitance of the liquid crystal 702 and the storage capacitance 7 are reduced.
Based on the electric charge held in the capacitance of No. 18, the voltage application to the liquid crystal 702 is continued until the next scanning period. Note that the storage capacitor 718 may form a capacitor between the storage capacitor 718 and a dedicated capacitor line as described above.

Although not shown, the incident side polarizing plate and / or
Alternatively, the reflective polarizing plate on the emission side is provided on each of the substrates 701, 7
00 is adhered to or adhered to the outer surface as needed.

[Other Embodiments] In each of the embodiments described above, the setting of the polarization axis is not limited to the embodiment, but can be set as appropriate without departing from the spirit of the present invention.

In each of the above-mentioned embodiments, for example, a cholesteric liquid crystal layer sandwiched between λ / 4 plates and a Brewster angle-based film (SID 92DIGEST pp. 427 to 4) are used instead of the multilayer structure film.
29), and those utilizing holograms may be used.
It is known that these also have the same function as the multilayer structure film in the above-described embodiment.

As the projection type display device, there are a front projection type in which projection is performed from the side where the projection surface is observed, and a rear projection type in which projection is performed from the side opposite to the direction in which the projection surface is observed. However, the projection display devices according to the above-described embodiments can be applied to any type.

[0130]

As described above, according to the present invention, the polarizing means of the liquid crystal panel in the light valve of the projection display absorbs light and does not generate heat unlike the conventional polarizing plate. It is possible to prevent the polarization characteristics from deteriorating and the liquid crystal panel from being affected by heat. Further, since the polarizing means is a film having a multilayer structure, the optical system does not increase in size. Further, since the heat generation is drastically reduced, the cooling mechanism can be simplified, for example, it is not necessary to eliminate the cooling means or take special measures to increase the cooling efficiency of the cooling means. Further, the light reflected by the film is re-reflected on the light source side, so that the light use efficiency can be improved.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of a projection display apparatus according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a projection display apparatus showing a third embodiment of the present invention.

4A and 4B are views showing a polarization beam splitter array (polarization converter) in FIG.

FIG. 5 is a diagram illustrating the operation of the liquid crystal light valve of the present invention.

FIG. 6 is a diagram showing details of a polarizing means used in the present invention.

FIG. 7 is a view showing wavelength selective transmission characteristics of a polarizing means of each liquid crystal light valve.

FIG. 8 is a configuration diagram of a conventional projection display device.

FIG. 9 is a view for explaining the operation of a conventional liquid crystal light valve.

FIG. 10 is a sectional view of a liquid crystal panel according to the present invention.

FIG. 11 is a plan view (A) and an equivalent circuit diagram (B) of a liquid crystal panel according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Light source part 11 ... Lamp 12 ... Reflector 13, 14 ... Dichroic mirror 15, 16, 17 ... Reflection mirror 18 ... Incident lens 19 ... Relay lens 20 ... Outgoing lens 22 ... Light guide means 23, 24, 25 ... Liquid crystal panel 29, 31, 33 ... Incident side polarizing plate 30, 32, 34 ... Outgoing side reflective polarizing plate 26 ... Cross dichroic Prism 27 Projection lens 28 Screen 501 502 Incident light 503 Incident side polarizing plate 504 Liquid crystal panel 505 Outgoing side reflective polarizing plate 510 Red light 520: wavelength selective transmission characteristics of the polarization means of the light valve for green light 520: wavelength selective transmission characteristics of the polarization means of the light valve for green light 530: wavelength selection transmission characteristics of the light valve for blue light Long permselective properties

Claims (9)

[Claims] 1. A light source, a polarization conversion unit capable of aligning light from the light source with light having one polarization axis component and emitting the light, a light valve for modulating light emitted from the polarization conversion unit, and the light valve And a projection optical unit for projecting light modulated by the light valve, the light valve is disposed on a liquid crystal panel and at least a light emission side of the liquid crystal panel, and mainly transmits light of one polarization axis component and transmits the other light. A projection display device comprising a polarizing means for mainly reflecting light of a polarization axis component. 2. The projection type display device according to claim 1, wherein said projection type display device is provided between said reflection polarizing plate and said projection means, and mainly transmits light of one polarization axis component. A projection display device comprising a polarizing plate that mainly absorbs light having a polarization axis component different from one polarization axis component. 3. The projection display device according to claim 1, wherein the light valve is disposed on a light incident side of the liquid crystal panel, and emits light from the polarization conversion unit. A projection display device, further comprising a polarizing plate that mainly transmits light of the other polarization axis component and mainly absorbs light of the other polarization axis component. 4. The projection display device according to claim 1, wherein the light source is a light source lamp that emits light, and is reflected by the light emitted from the light source lamp and the polarizing unit. And a reflection mirror for reflecting the reflected light to the reflective polarizing plate side. 5. The projection type display device according to claim 1, wherein the light from the light source is separated into a plurality of color lights, and the light is separated by the separation means. A projection display device, further comprising: a plurality of the light valves that respectively modulate color lights; and a combining unit that combines the color lights modulated by the plurality of light valves. 6. The projection display device according to claim 1, wherein said polarizing means has a refractive index in a first axial direction and a refractive index in a second axial direction orthogonal to the first axial direction. First films different from each other, and second films having a refractive index in the first axial direction and a refractive index in the second axial direction substantially equal to a refractive index in the second axial direction of the first film are alternately laminated. A projection type display device characterized in that the projection type display device is a multi-layer structure film. A polarizing plate that is provided between the light source and the projection means and mainly transmits light of the one polarization axis component and mainly absorbs light of a polarization axis component different from the one polarization axis component. A projection display device characterized by the above-mentioned. 7. The projection type display device according to claim 1, wherein the light from the light source is separated into a plurality of color lights, and the light is separated by the separation means. A projection display device, further comprising: a plurality of the light valves that respectively modulate color lights; and a combining unit that combines the color lights modulated by the plurality of light valves. 8. A light source, a light valve for modulating light from the light source, and projection optical means for projecting light modulated by the light valve, the light valve comprising: a liquid crystal panel; A polarizing means that is arranged on the light emission side of the panel, mainly transmits light of one polarization axis component and mainly reflects light of the other polarization axis component, and is arranged on the light incidence side of the liquid crystal panel; A projection display device comprising: a polarizing plate mainly transmitting light of a polarization axis component and mainly absorbing light of the other polarization axis component. 9. A light source, a light valve for modulating light from the light source, and projection optical means for projecting light modulated by the light valve, the light valve comprising: a liquid crystal panel; and the liquid crystal panel. At least on the light emission side of the liquid crystal panel. Pinched,
A switching element and a pixel electrode connected thereto are formed in a matrix on one inner surface of the substrate arranged on the light incident side, and a light-shielding layer is provided at a position corresponding to the switching element on the other substrate. A projection display device, wherein the projection display device is provided.