JP3972927B2 - Projection display - Google Patents

Description

  The present invention relates to a projection display device provided with light combining means such as a cross dichroic prism.

  A cross-dichroic prism may be used in a projection display device that projects a color image on a projection screen. The cross dichroic prism is an optical element that combines light of three colors, red, green, and blue, and emits the light in the same direction. As such a projection display device, for example, a device described in JP-A-1-302385 is known.

  FIG. 16 is a conceptual diagram showing a main part of the projection display device. The projection display device includes three liquid crystal light valves 42, 44, 46, a cross dichroic prism 48, and a projection lens system 50. The liquid crystal light valves 42, 44, 46 are configured by sandwiching a liquid crystal panel between two polarizing plates set so that the change axes are orthogonal to each other. The cross dichroic prism 48 synthesizes light of three colors red, green, and blue modulated by the three liquid crystal light valves 42, 44, and 46 and emits the light in the direction of the projection lens system 50. The projection lens system 50 focuses the synthesized light on the projection screen 52.

  As shown in FIG. 16, on the cross dichroic prism 48, a red reflecting film 61 and a blue reflecting film 62 are formed in a substantially X shape. The red reflecting film 61 and the blue reflecting film 62 can be formed as a dielectric multilayer film having a higher reflectance with respect to s-polarized light in a wider wavelength region than p-polarized light. In the above-described projection display device disclosed in Japanese Patent Laid-Open No. 1-302385, red light among the three colors of light incident on the cross dichroic prism 48 using such a red reflective film 61 and blue reflective film 62 is used. Reflection characteristics in the cross dichroic prism 48 are improved by making blue light incident as s-polarized light and green light incident as p-polarized light. Specifically, when red light and blue light having random polarization directions are respectively incident on the liquid crystal light valves 42 and 46 for red light and blue light, s-polarized red light and blue light are respectively emitted. The light enters the cross dichroic prism 48. Here, the property that the liquid crystal light valve generally emits only predetermined linearly polarized light is utilized. On the other hand, when green light having a random polarization direction is incident on the liquid crystal light valve 44 for green light, p-polarized green light is emitted and incident on the cross dichroic prism 48.

  In the above-described conventional projection display apparatus, light having a random polarization direction is incident on the three liquid crystal light valves. Therefore, in each of the liquid crystal light valves 42, 44, and 46, the polarization direction orthogonal to the transmitted polarization component is obtained. The polarization component is absorbed. As a result of such light absorption, heat is generated in the liquid crystal light valves 42, 44, and 46, which adversely affects the liquid crystal light valve and optical elements in the vicinity thereof. The same applies to the case where light modulation means other than the liquid crystal light valve is used.

  This is also the case when the cross dichroic 48 is replaced with a cross dichroic mirror configured so that two dichroic mirrors each having a red reflecting film 61 and a blue reflecting film 62 are crossed in a substantially X shape. It is the same.

  The present invention has been made to solve the above-described problems in the prior art, and reduces the heat generation in the vicinity of the light modulation means, and also improves the reflection characteristics in the cross dichroic prism and cross dichroic mirror. An object is to provide a display device.

In order to solve at least a part of the above-described problems, a projection display device of the present invention includes:
A light source;
First polarization conversion means for converting incident light from the light source into polarized light having a predetermined polarization direction;
Color light separating means for separating light emitted from the first polarization conversion means into three colors of light;
First light modulation means for receiving light of the first color separated by the color light separation means and modulating the light based on a first image signal;
Second light modulation means for receiving light of the second color separated by the color light separation means and modulating the light based on a second image signal;
Third light modulation means for receiving the light of the third color separated by the color light separation means and modulating the light based on a third image signal;
Color synthesizing means for synthesizing the three color lights respectively modulated by the first to third light modulating means and emitting them in the same direction;
A projection optical system that projects the light combined by the color combining means;
Linearly polarized light that is provided on the optical path between the first polarization conversion unit and the color synthesis unit and that has the first color and the third color incident on the color synthesis unit and has a first polarization direction. And at least one of the three color lights so that the second color light incident on the color synthesizing means is linearly polarized light having a second polarization direction orthogonal to the first polarization direction. A second polarization conversion means for adjusting the polarization direction,
The color composition means
A first reflective film for reflecting the first color light and a second reflective film for reflecting the third color light, which are provided so as to intersect substantially in an X shape.

  Since the first polarization conversion means (polarization conversion element) converts light from the light source into predetermined polarized light, there is almost no absorption of light here, and there is little heat generation. The three colors of light separated by the color light separating means have the polarization direction of the predetermined polarized light. The second polarization conversion means adjusts the polarization direction of at least one of the three colors of light to convert the first color light and the third color light into linearly polarized light having the first polarization direction. At the same time, the second color light is changed to linearly polarized light having the second polarization direction. Accordingly, linearly polarized light to be modulated by the light modulation means is incident on each light modulation means. Therefore, the light modulation means hardly absorbs light, and heat generation due to this is small. Further, the three colors of light are almost emitted from the color synthesizing unit after passing through the light modulating unit. Therefore, there is little heat generation due to the light returning from the color synthesizing means to the light modulating means and absorbed. The second polarization conversion unit may be installed on the optical path between the first polarization conversion unit and the color synthesis unit. For example, the second polarization conversion unit may be installed on the optical path between the color light separation unit and the light modulation unit. Alternatively, it may be installed on the optical path between the light modulating means and the color synthesizing means.

In the projection display device, the first polarization conversion unit emits linearly polarized light having the first polarization direction,
The first to third light modulators receive linearly polarized light having the first polarization direction as incident light, respectively, and modulate the incident light based on the first to third image signals. To emit linearly polarized light having the second polarization direction,
The second polarization conversion means includes:
Linearly polarized light having the second polarization direction, which is provided on the optical path between the first light modulating unit and the color synthesizing unit and is emitted from the first light modulating unit, is converted into the first polarized light. A first retardation plate that is converted into linearly polarized light having a polarization direction and is incident on the color combining means;
Linearly polarized light having the second polarization direction, which is provided on the optical path between the third light modulating unit and the color synthesizing unit and is emitted from the third light modulating unit, is converted into the first polarized light. A second retardation plate that is converted into linearly polarized light having a polarization direction and is incident on the color synthesizing unit.

Alternatively , the first polarization conversion means emits linearly polarized light having the second polarization direction ,
The first to third light modulating means receives the linearly polarized light each having the second polarization direction as the incident light, to the first not modulating the respective incident light based on the third image signal To emit linearly polarized light having the first polarization direction,
The second polarization conversion means includes:
Provided on an optical path between the second light modulating means and the color synthesizing means for converting the second color light from the first polarization direction into linearly polarized light having the second polarization direction; A phase difference plate that is incident on the color synthesizing unit may be provided.

Alternatively, the first polarization conversion means emits linearly polarized light having the first polarization direction ,
The second polarization conversion means includes a first retardation plate provided between the first polarization conversion means and the first to third light modulation means, a second light modulation means, You may make it provide the 2nd phase difference plate provided between the said color synthesis means .

Alternatively, each of the first to third light modulators includes an incident-side polarizing plate that transmits light of a specific polarization direction on the light incident side,
The second polarization conversion unit has the first color incident on the color combining unit, with the light incident on the first to third light modulation units having a polarization direction transmitted through the incident-side polarizing plate. And the third color light is converted into linearly polarized light having a first polarization direction, and the second color light incident on the color combining means has a second polarization direction orthogonal to the first polarization direction. You may make it provide the at least 1 phase difference plate used as linearly polarized light .

Other aspects of the invention

The present invention includes other aspects as follows. That is, the projection display device of the first aspect is
A light source;
Color light separating means for separating the light emitted from the light source into light of three colors;
First light modulation means for receiving light of the first color separated by the color light separation means and modulating the light based on a first image signal;
Second light modulation means for receiving light of the second color separated by the color light separation means and modulating the light based on a second image signal;
Third light modulation means for receiving the light of the third color separated by the color light separation means and modulating the light based on a third image signal;
Color synthesizing means for synthesizing the three color lights respectively modulated by the first to third light modulating means and emitting them in the same direction;
A projection optical system for projecting the light synthesized by the color synthesis means,
From the first and third light modulation means, linearly polarized light having a first polarization direction is emitted,
From the second light modulation means, linearly polarized light having a second polarization direction is emitted,
On the light path on the emission side of the color synthesizing means, the three colors of light emitted from the color synthesizing means are converted into linearly polarized light components having the first polarization direction and linearly polarized light having the second polarization direction. Polarization conversion means for converting into polarized light containing components, respectively,
The color composition means
A first reflective film for reflecting the first color light and a second reflective film for reflecting the third color light, which are provided so as to intersect substantially in an X shape.

  According to the projection display device of the first aspect, the color light having the first polarization direction and the color light having the second polarization direction emitted from the color synthesizing means are respectively converted into the first and second linearly polarized lights. Since conversion is performed so as to include components, it is possible to project a color image onto a screen that reflects only a polarization component in one polarization direction, such as a polarization screen.

  In the first aspect, the polarization conversion means may include a λ / 2 phase difference plate. If a λ / 2 phase difference plate is used, linearly polarized light including two linearly polarized light components can be obtained. At this time, it is particularly preferable to convert the linearly polarized light component having the first and second polarization directions into linearly polarized light that includes about ½ each.

  Alternatively, the polarization conversion unit may include a λ / 4 retardation plate. If a λ / 4 retardation plate is used, elliptically polarized light obtained by combining two linearly polarized light components can be obtained. Among elliptically polarized light, circularly polarized light is particularly preferable.

The projection display device of the second aspect is
A light source;
Color light separating means for separating the light emitted from the light source into light of three colors;
Three light modulation means for receiving the light of the three colors and modulating the light based on the image signals given thereto, and emitting the light as linearly polarized light;
Color synthesizing means for synthesizing the modulated lights of the three colors respectively modulated by the three light modulating means and emitting them in the same direction;
A projection optical system that projects the light combined by the color combining means;
In addition,
On the optical path between at least one of the light modulator and the color synthesizer, a first and a second retardation plate having equal phase differences are provided,
The second retardation plate is affixed to the incident surface of the color synthesizing unit, and the optical axes of the first and second retardation plates are polarized light of modulated light incident on the first retardation plate. The direction and the polarization direction of the modulated light emitted from the second retardation plate are set to be equal.

  According to the projection display device of the second aspect, since the second retardation plate is attached to the incident surface of the light combining means, the reflection of light at the interface between the second retardation plate and the light combining means is It hardly occurs. Therefore, it is possible to prevent malfunction of the light modulation means caused by the light reflected by the incident surface of the light combining means and returning to the light modulation means again.

  In the second aspect, the first and second retardation plates may be λ / 4 retardation plates. Further, a λ / 2 retardation plate may be used.

  In particular, when a λ / 4 phase difference plate is used, the light reflected from the λ / 4 phase difference plate attached to the color synthesizing unit out of the light emitted from the light modulation unit returns to its polarization. It becomes polarized light with different directions. And since this reflected light is absorbed by the polarizing plate provided in the light-projection surface side of a light modulation means, the malfunction of a light modulation means can be prevented.

A. First embodiment:
Next, embodiments of the present invention will be described based on examples. FIG. 1 is a schematic plan view of a projection display device according to a first embodiment of the present invention. The projection display device includes an illumination optical system 100, dichroic mirrors 210 and 212, reflection mirrors 220, 222, and 224, relay lenses 230 and 232, three field lenses 240, 242, and 244, and two sheets. Λ / 2 phase difference plates 310 and 312, three liquid crystal light valves 250, 252 and 254, a cross dichroic prism 260, and a projection lens system 270.

  The illumination optical system 100 includes a light source 110 that emits a substantially parallel light beam, a first lens array 120, a second lens array 130, and a polarization conversion element 140 that converts incident light into a predetermined linearly polarized light component. , A reflection mirror 150 and a condenser lens 160 are provided. The illumination optical system 100 is an optical system for illuminating the three liquid crystal light valves 250, 252, and 254 that are illuminated areas substantially uniformly.

  The light source 110 includes a light source lamp 112 as a radiation light source that emits a radial light beam, and a concave mirror 114 that emits radiation light emitted from the light source lamp 112 as a substantially parallel light beam. As the concave mirror 114, a parabolic mirror is preferably used.

  FIG. 2 is a perspective view showing the external appearance of the lens arrays 120 and 130. The first lens array 120 has a configuration in which small lenses 122 having a substantially rectangular outline are arranged in a matrix of M rows and N columns. In this example, M = 10 and N = 8. The second lens array 130 also has a configuration in which small lenses are arranged in a matrix of M rows and N columns so as to correspond to the small lenses 122 of the first lens array 120. Each small lens 122 divides a parallel light beam incident from the light source 110 (FIG. 1) into a plurality of (that is, M × N) partial light beams, and connects each partial light beam in the vicinity of the second lens array 130. Let me image. The external shape of each small lens 122 viewed from the z direction is set to be substantially similar to the shape of the liquid crystal light valves 250, 252, and 254. In this embodiment, the aspect ratio (ratio between horizontal and vertical dimensions) of the small lens 122 is set to 4: 3.

  The polarization conversion element 140 has a function as the first polarization conversion means of the present invention. FIG. 3 is an explanatory diagram showing the configuration of the polarization conversion element 140 (FIG. 1). The polarization conversion element 140 includes a polarization beam splitter array 141 and a selective phase difference plate 142. The polarizing beam splitter array 141 has a shape in which a plurality of columnar translucent plates 143 each having a parallelogram cross section are alternately bonded. Polarization separation films 144 and reflection films 145 are alternately formed on the interface of the translucent plate 143. The polarizing beam splitter array 141 is formed by laminating a plurality of plate glasses formed with these films so that the polarization separating films 144 and the reflecting films 145 are alternately arranged, and obliquely cutting at a predetermined angle. Created by. The polarization conversion element 140 increases the light use efficiency in the projection display device by converting all the light of the light source 110 having a random polarization direction into s-polarized light. Further, since the polarization conversion element 140 hardly absorbs light, there is little heat generation due to this.

  The light that has passed through the first and second lens arrays 120 and 130 is separated into s-polarized light and p-polarized light by the polarization separation film 144. The s-polarized light is reflected substantially perpendicularly by the polarization separation film 144 and further reflected vertically by the reflective film 145 before being emitted. On the other hand, the p-polarized light passes through the polarization separation film 144 as it is. In the selective phase difference plate 142, a λ / 2 retardation layer 146 is formed on the light exit surface portion of the light passing through the polarization separation film 144, and the light exit surface portion reflected by the reflection film 145 is colorless and transparent. It is an optical element. Therefore, the p-polarized light transmitted through the polarization separation film 144 is converted into s-polarized light by the λ / 2 retardation layer 146 and emitted. As a result, all the light beams having random polarization directions incident on the polarization conversion element 140 are emitted as s-polarized light. If the position of the λ / 2 retardation layer 146 is moved to the exit surface side of the reflective film 145, all the emitted light can be converted into p-polarized light.

  As can be seen from FIG. 3A, the center of the two s-polarized lights emitted from the polarization conversion element 140 (the center of the two s-polarized lights) is the center of the incident random light beam (s-polarized light + p-polarized light). Rather than in the x direction. This shift amount is equal to the width Wp of the λ / 2 retardation layer 146 (that is, the width of the polarization separation film 144 in the x direction). For this reason, as shown in FIG. 1, the optical axis (indicated by a two-dot chain line) of the light source 110 is shifted from the system optical axis (indicated by a one-dot chain line) after the polarization conversion element 140 by a distance D equal to Wp / 2. Is set to the correct position.

  In the projection display device shown in FIG. 1, the parallel light beam emitted from the light source 110 is divided into a plurality of partial light beams by the first and second lens arrays 120 and 130. The small lens 122 of the first lens array 120 forms an image of each partial light beam in the vicinity of the polarization separation film 144 (FIG. 3) of the polarization conversion element 140. The small lens 132 of the second lens array 130 has a function of forming an image of the light source image in the first lens array 120 with the liquid crystal light valves 250, 252 and 254. The partial light beams emitted from the small lenses 132 of the second lens array 130 are reflected by the reflection mirror 150 and enter the condenser lens 160. The condensing lens 160 has a function as a superimposing optical system that superimposes the plurality of partial light beams on the liquid crystal light valves 250, 252, and 254 that are illuminated areas. As a result, the liquid crystal light valves 250, 252, and 254 are illuminated almost uniformly.

  The two dichroic mirrors 210 and 212 have a function as color light separating means for separating the white light condensed by the condenser lens 160 into three color lights of red, green, and blue. The first dichroic mirror 210 transmits the red light component of the white light beam emitted from the illumination optical system 100 and reflects the blue light component and the green light component. The red light transmitted through the first dichroic mirror 210 is reflected by the reflection mirror 220, passes through the field lens 240 and the λ / 2 phase difference plate 310, and reaches the red light liquid crystal light valve 250. The field lens 240 has a function of forming a light source image in the vicinity of the second lens array 130 in the projection lens system 270. Each partial light beam that has passed through the field lens 240 becomes a substantially parallel light beam. The same applies to the field lenses 242 and 244 provided in front of other liquid crystal light valves.

  As will be described in detail later, the λ / 2 phase difference plate 310 has a function as second polarization conversion means for rotating the polarization direction of red light by 90 degrees and causing it to enter the liquid crystal light valve 250. The λ / 2 phase difference plate 312 for blue light also has a function as a second polarization conversion unit that changes the polarization direction of the blue light by 90 degrees and enters the liquid crystal light valve 254.

  Of the blue light and green light reflected by the first dichroic mirror 210, the green light is reflected by the second dichroic mirror 212, passes through the field lens 242 and reaches the liquid crystal light valve 252 for green light. On the other hand, the blue light passes through the second dichroic mirror 212, passes through the relay lens system including the relay lenses 230 and 232 and the reflection mirrors 222 and 224, and further passes through the field lens 244 and the λ / 2 phase difference plate 312. To the liquid crystal light valve 254 for blue light.

  The three liquid crystal light valves 250, 252, and 254 have a function as light modulation means for forming an image by modulating light of three colors according to given image information (image signal). The cross dichroic prism 260 has a function as color synthesizing means for synthesizing three color lights to form a color image. The combined light generated by the cross dichroic prism 260 is emitted in the direction of the projection lens system 270. The projection lens system 270 functions as a projection optical system that projects the combined light on the projection screen 300 and displays a color image.

  FIG. 4 is a conceptual diagram showing the main part of the first embodiment. In FIG. 4, the optical system from the polarization conversion element 140 to the cross dichroic prism 260 is drawn paying attention to the polarization direction. An optical element (lens or the like) that is hardly related to the polarization direction is not shown.

  In the first embodiment, light having a random polarization direction enters the polarization conversion element 140 and only s-polarized light is emitted. The s-polarized white light is separated into red light R, green light G, and blue light B by the two dichroic mirrors 210 and 212 as described above. Since the polarization direction does not change when passing through the dichroic mirrors 210 and 212, the three colors of light remain as s-polarized light. In this example, s-polarized light corresponds to linearly polarized light having the first polarization direction in the present invention, and p-polarized light corresponds to linearly polarized light having the second polarization direction.

  The s-polarized red light is reflected by the reflection mirror 220 and then converted to p-polarized light by the λ / 2 phase difference plate 310. This p-polarized red light is incident on the first liquid crystal light valve 250. The first liquid crystal light valve 250 includes a liquid crystal panel 402, a p-polarized light transmitting polarizing plate 404 provided on the incident side of the liquid crystal panel 402, and an s-polarized light transmitting polarizing plate 406 provided on the output side. ing. The p-polarized red light incident on the first liquid crystal light valve 250 passes through the p-polarized light transmitting polarizing plate 404 as it is, and is modulated by the liquid crystal panel 402 so that a part thereof is converted into s-polarized light. Only polarized light is transmitted through the s-polarized light polarizing plate 406 and emitted. Therefore, the red light emitted from the first liquid crystal light valve 250 is s-polarized light. As described above, the red light incident on the first liquid crystal light valve 250 is adjusted in advance to linearly polarized light to be modulated by the liquid crystal light valve 250 (that is, linearly polarized light transmitted through the polarizing plate 404 on the incident side). Therefore, in the vicinity of the liquid crystal light valve 250, there is almost no decrease in light utilization efficiency due to absorption, and there is little heat generation.

  The s-polarized green light separated by the second dichroic mirror 212 is incident on the second liquid crystal light valve 252 as it is. The second liquid crystal light valve 252 includes a liquid crystal panel 412, an s-polarized light transmitting polarizing plate 414 provided on the incident side of the liquid crystal panel 412, and a p-polarized light transmitting polarizing plate 416 provided on the output side. ing. The s-polarized green light incident on the second liquid crystal light valve 252 passes through the s-polarized light transmitting polarizing plate 414 as it is, and is modulated by the liquid crystal panel 412 so that a part thereof is converted into p-polarized light. Only the polarized light is transmitted through the p-polarized light transmitting polarizing plate 416 and emitted. Accordingly, the green light emitted from the second liquid crystal light valve 252 is p-polarized light. As described above, the green light incident on the second liquid crystal light valve 252 is adjusted in advance to linearly polarized light (linearly polarized light transmitted through the incident-side polarizing plate 414) to be modulated by the liquid crystal light valve 252. Therefore, there is almost no light absorption in the vicinity of the liquid crystal light valve 252, and little heat is generated.

  The s-polarized blue light separated by the second dichroic mirror 212 is reflected by the reflection mirrors 222 and 224 and then converted to p-polarized light by the λ / 2 phase difference plate 312. This p-polarized blue light is incident on the third liquid crystal light valve 254. The third liquid crystal light valve 254 includes a liquid crystal panel 422, an s-polarized light transmitting polarizing plate 424 provided on the incident side of the liquid crystal panel 422, and a p-polarized light transmitting polarizing plate 426 provided on the output side. ing. This is the same as the first liquid crystal light valve 250. Accordingly, only the s-polarized green light incident on the second liquid crystal light valve 252 is converted into p-polarized light. In this way, the blue light incident on the third liquid crystal light valve 254 is preliminarily adjusted to linearly polarized light to be modulated by the liquid crystal light valve 254, so that light absorption near the liquid crystal light valve 254 is absorbed. There is almost no fever.

  On the cross dichroic prism 260, a blue reflective film 264 and a red reflective film 266 are formed in a substantially X shape. The s-polarized red light modulated by the first liquid crystal light valve 250 is reflected by the red reflecting film 266 and is emitted in the direction of the projection lens system 270 (FIG. 1). Similarly, the s-polarized blue light modulated by the third liquid crystal light valve 254 is also reflected by the blue reflecting film 264 and emitted in the direction of the projection lens system 270. The p-polarized green light modulated by the second liquid crystal light valve 252 passes through the blue reflection film 264 and the red reflection film 266 as it is, and is emitted in the direction of the projection lens system 270. In FIG. 4, for convenience of illustration, the positions where the red light and the blue light are reflected are drawn at positions slightly deviated from the respective reflection films.

  5 and 6 are graphs showing examples of spectral reflectance characteristics of the red reflective film 266 and the blue reflective film 264. FIG. 5 and 6, the reflectance characteristic for s-polarized light is drawn with a broken line, and the reflectance characteristic for p-polarized light is drawn with a solid line. In this specification, a wavelength region having a reflectance of 50% or more is referred to as an “effective reflection wavelength region”, and a wavelength at which the reflectance is 50% is referred to as a “cut-off wavelength”.

  The wavelength range of blue light is usually about 400 nm to about 500 nm, the wavelength range of green light is usually set to about 500 nm to about 580 nm, and the wavelength range of red light is usually set to about 580 nm to about 700 nm. As can be seen from FIG. 5, the effective reflection wavelength region (about 530 nm to about 750 nm) for the s-polarized light of the red reflective film 266 includes the effective reflection wavelength region (about 600 nm to about 700 nm) for the p-polarized light, and is wider than this. It is in the wavelength range. As described with reference to FIG. 4, since the red light is incident on the cross dichroic prism 260 as s-polarized light, the red light is reflected almost 100% by the red reflecting film 266 having the characteristics shown in FIG. On the other hand, since the green light is incident on the cross dichroic prism 260 as p-polarized light, the green light is transmitted through the red reflecting film 266 having the characteristics shown in FIG.

  On the other hand, as can be seen from FIG. 6, the effective reflection wavelength region (about 390 nm to about 530 nm) for the s-polarized light of the blue reflective film 264 includes the effective reflection wavelength region (about 400 nm to about 460 nm) for the p-polarized light, The wavelength range is wider than this. Since the blue light is incident on the cross dichroic prism 260 as s-polarized light, the blue light is reflected with a considerably high reflectance of about 80% or more by the blue reflecting film 264 having the characteristics shown in FIG. On the other hand, since the green light is incident on the cross dichroic prism 260 as p-polarized light, the green light is transmitted almost 100% through the blue reflecting film 264 having the characteristics shown in FIG.

  As described above, the red reflection film 266 and the blue reflection film 264 have better reflectance characteristics for s-polarized light than reflectance characteristics for p-polarized light. Therefore, by making red light and blue light incident on the cross dichroic prism 260 as s-polarized light and making green light incident on the cross dichroic prism 260 as p-polarized light, a high reflectance for red light and blue light is obtained. On the other hand, transmittance can be obtained for green light. As a result, the utilization efficiency of the three colors of light can be increased.

  In general, the reflectance characteristics of the red reflecting film 266 and the blue reflecting film 264 depend on the incident angle of light to the cross dichroic prism 260. Specifically, when the incident angle changes, the slope of the graph near the cutoff wavelength becomes gentle. However, in the reflectance characteristics of the red reflecting film shown in FIG. 5, the green light incident with p-polarized light is transmitted almost 100%, and the red light incident with s-polarized light is reflected almost 100%. There is considerable room. Therefore, even if the incident angle to the cross dichroic prism 260 is slightly changed, the reflectance for red light and the transmittance for green light are hardly changed. The same applies to the blue reflective film 264. As described above, since the reflection characteristics are not greatly influenced by the incident angle of the incident light, it is possible to enter not only a parallel light beam but also a slightly convergent light beam as the three colors of light incident on the cross dichroic prism 260. is there. If a convergent light beam is incident, the load on the projection lens system 270 can be reduced. That is, the number of projection lens systems 270 can be reduced, and there is an advantage that it is not necessary to use a high-performance expensive lens.

  The red, blue, and green wavelength bands incident on the liquid crystal light valves 250, 252, and 254, that is, the red, blue, and green hues, are the first dichroic mirror 210 and the second dichroic that are color separation means. It is determined by the selected wavelength region of the mirror 212. Accordingly, only light in a predetermined wavelength band selected by the first or second dichroic mirrors 210 and 212 is incident on the red reflecting film 266 and the blue reflecting film 264 of the cross dichroic prism 260. That is, the red, blue, and green wavelength bands do not need to be determined again by the red reflecting film 266 and the blue reflecting film 264 of the dichroic prism 260. Therefore, even if the reflection bands of the red reflection film 266 and the blue reflection film 264 are considerably wider than the predetermined wavelength band to be selected by the dichroic mirror 210, the hues of red, blue, and green do not change. It is convenient because loss can be reduced.

  Here, as shown in FIG. 5, the reflection band for the s-polarized light of the red reflecting film 266 is wider than the wavelength band (usually about 580 nm to 700 nm) to be selectively transmitted by the first dichroic mirror 210. In addition, as shown in FIG. 6, the reflection band for the s-polarized light of the blue reflecting film 264 is wider than the wavelength region (usually about 400 to 500 nm) to be selectively transmitted by the second dichroic mirror 212. The amount of transmission of green light incident as p-polarized light does not decrease. This is because, as can be seen from the graph of p-polarized light incidence indicated by solid lines in FIGS. 5 and 6, the wavelength band of green light incident as p-polarized light (usually about 500 to 580 nm) is the red reflective film 266, blue This is because the light passes through the reflective film 264 almost.

  Furthermore, in the first embodiment, since the polarization directions of the red light and the blue light and the polarization direction of the green light are orthogonal to each other, the crosstalk between the three liquid crystal light valves 250, 252, and 254 can be prevented. There is also an advantage. Here, “crosstalk” refers to a phenomenon in which the liquid crystal light valve malfunctions when the back surface of the liquid crystal light valve is irradiated with reflected light from the cross dichroic prism 260.

  Here, a liquid crystal light valve having a liquid crystal panel (polysilicon TFT liquid crystal panel) using a polysilicon TFT as a pixel switching element, which is generally employed as the liquid crystal light valve 250, 252, 254, is taken as an example. The principle of crosstalk generation will be described in more detail.

  The liquid crystal panel has a structure in which liquid crystal is sandwiched between a pair of substrates. As is well known, in the case of a polysilicon TFT liquid crystal panel, a polysilicon TFT is provided as a pixel switching element on one of the two substrates, and a counter electrode is formed on the other substrate. FIG. 7 is a diagram for explaining an example of a polysilicon TFT liquid crystal panel. Of the two substrates of the polysilicon TFT liquid crystal panel, a part of the substrate 430 on the side where the polysilicon TFT is provided and the polysilicon TFT panel. A part of the polarizing plate 440 provided outside is shown in a sectional view. The polysilicon TFT 450 includes an active layer 432 made of polysilicon formed on the substrate 430, and a gate 434 made of polysilicon or the like formed on the gate insulating layer 433 therebetween. A source electrode 436 that supplies ON / OFF signals to the polysilicon TFT 450 is connected to the active layer 432 through a hole provided in a part of the interlayer insulating film 435. The pixel electrode 431 is also connected to the active layer 432. Information relating to image modulation is written by turning on the polysilicon TFT 450 and applying a voltage to the liquid crystal sandwiched between the pixel electrode 431 and the counter electrode. After the writing is completed, the polysilicon TFT 450 is turned off in order to hold the written information until the next information is written.

  However, since the polysilicon TFT liquid crystal panel is disposed with the substrate 430 side on which the polysilicon TFT 450 is formed facing the cross dichroic prism 260, the reflected light from the cross dichroic prism 260 is indicated by an arrow in the figure. Irradiate the polysilicon TFT liquid crystal panel from the direction. When the reflected light reaches the active layer 432, carriers due to photoexcitation are generated in the active layer 405, and a current (so-called light leakage current) is generated even though the polysilicon TFT 450 is turned off. End up. As a result, the voltage applied to the liquid crystal changes and the state of image modulation is disturbed.

  However, according to the configuration of this example, such a problem can be prevented. Suppose that green light is reflected by the red reflecting film 266 and irradiates the back surface of the third light valve 254 in FIG. Also in this case, since the green light is p-polarized light, it is shielded by the s-polarized light transmitting polarizing plate 426 on the emission side of the third liquid crystal light valve 254 and does not reach the liquid crystal panel 422. Accordingly, it is possible to prevent crosstalk from occurring in the third liquid crystal light valve 254 due to green light. Similarly, crosstalk is prevented from occurring in the first liquid crystal light valve 250 due to green light, and crosstalk is also prevented from occurring in the second liquid crystal light valve 252 due to blue light. This prevention of crosstalk works similarly between the second liquid crystal light valve 252 and the third liquid crystal light valve 254.

  The red light that has passed through the first liquid crystal light valve 250 hardly reaches the third liquid crystal light valve 254. This is because the reflection band of the red reflection film 266 can be set to be considerably wider than the band determined by the first dichroic mirror 210, and almost all red light can be reflected by the red reflection film 266. The same applies to blue light. As described above, according to this example, it is possible to solve the problem of crosstalk due to light transmitted through the red reflecting film 266 and the blue reflecting film 264.

  As described above, the first embodiment is advantageous in that the light use efficiency is high throughout the projection display apparatus and that heat generation due to light absorption is small.

B. Second embodiment:
FIG. 8 is a conceptual diagram showing the main part of the second embodiment. In the second embodiment, the two λ / 2 phase difference plates 310 and 312 of the first embodiment shown in FIG. 4 are arranged on the light path on the emission side of the liquid crystal light valves 250 and 254, respectively. However, in the first liquid crystal light valve 250a in the second embodiment, an s-polarized light transmitting polarizing plate 404a is provided on the incident side, and a p-polarized light transmitting polarizing plate 406a is provided on the output side. . The first liquid crystal light valve 250a receives s-polarized red light, passes through the s-polarized light transmitting polarizing plate 404a as it is, is modulated by the liquid crystal panel 402a and is converted into p-polarized light, The light is transmitted through the p-polarized light transmitting polarizing plate 406a and emitted. Therefore, the red light emitted from the first liquid crystal light valve 250a of the second embodiment is p-polarized light. The same applies to the third liquid crystal light valve 254a. Other components are the same as those in the first embodiment. The p-polarized red light and blue light are converted to s-polarized light by the λ / 2 phase difference plates 310 and 312, respectively, and enter the cross dichroic prism 260.

  Also in the second embodiment, green light is incident on the cross dichroic prism 260 as p-polarized light, and red light and blue light are incident as s-polarized light. Therefore, the projection display apparatus of the second embodiment has the same effect as that of the first embodiment. Unlike the case of the first embodiment, in this embodiment, the same type of polarized light (s-polarized light) is incident on all the liquid crystal light valves 250a, 252 and 254a. Accordingly, the incident side polarizing plates of the liquid crystal light valves 250a, 252, and 254a are all s-polarizing polarizing plates 404a, 414, and 424a, and the outgoing-side polarizing plates are all p-polarizing polarizing plates 406a, 416, and 426a. Is the same. Therefore, in the second embodiment, in addition to the same effect as the first embodiment, there is an advantage that the structure of the three liquid crystal light valves 250a, 252 and 254a can be made common to reduce the types of components.

C. Third embodiment:
FIG. 9 is a conceptual diagram showing the main part of the third embodiment. In the third embodiment, the polarization conversion element 140 of the first embodiment shown in FIG. 4 is replaced with a polarization conversion element 140a that emits p-polarized light, and the two λ / 2 phase difference plates 310 and 312 are replaced. In addition, a λ / 2 phase difference plate 314 is disposed on the light path on the incident side of the second liquid crystal light valve 252. Other components are the same as those in the first embodiment.

  Also in the third embodiment, green light is incident on the cross dichroic prism 260 as p-polarized light, and red light and blue light are incident as s-polarized light. Therefore, the projection display apparatus of the third embodiment has the same effect as that of the first embodiment. Furthermore, in the case of the present embodiment, as compared with the case of the first embodiment, since only one λ / 2 phase difference plate 314 is arranged on the optical path, there is an advantage that the number of parts can be reduced.

D. Fourth embodiment:
FIG. 10 is a conceptual diagram showing the main part of the fourth embodiment. In the fourth embodiment, the λ / 2 retardation film 314 of the third embodiment shown in FIG. 8 is arranged on the light path on the emission side of the second liquid crystal light valve 252. However, in the second liquid crystal light valve 252a in the fourth embodiment, a p-polarized light transmitting polarizing plate 414a is provided on the incident side, and an s-polarized light transmitting polarizing plate 416a is provided on the output side. . The second liquid crystal light valve 252a receives p-polarized green light, passes through the p-polarized light transmitting polarizing plate 414a as it is, is modulated by the liquid crystal panel 412a, is converted into s-polarized light, The light is transmitted through the s-polarized light polarizing plate 416a and emitted. Accordingly, the green light emitted from the second liquid crystal light valve 252a of the fourth embodiment is s-polarized light. Other components are the same as those in the third embodiment. The s-polarized green light is converted into p-polarized light by the λ / 2 phase difference plate 314 and enters the cross dichroic prism 260.

  Also in the fourth embodiment, green light is incident on the cross dichroic prism 260 as p-polarized light, and red light and blue light are incident as s-polarized light. Therefore, the projection display apparatus of the fourth embodiment has the same effect as that of the first embodiment. Further, unlike the case of the first embodiment, the same type of polarized light (p-polarized light) is incident on all the liquid crystal light valves 250, 252a, and 254 in this embodiment. Accordingly, the incident-side polarizing plates of the liquid crystal light valves 250, 252a, and 254 are all p-polarizing polarizing plates 404, 414a, and 424, and the outgoing-side polarizing plates are all s-polarizing polarizing plates 406, 416a, and 426. Is the same. Therefore, in addition to the same effects as in the first embodiment, the fourth embodiment also has an advantage that the structure of the three liquid crystal light valves 250, 252a, and 254 can be shared to reduce the types of components. Furthermore, in the case of the present embodiment, as compared with the case of the first embodiment, since only one λ / 2 phase difference plate 314 is arranged on the optical path, there is an advantage that the number of parts can be reduced.

E. Example 5:
FIG. 11 is a conceptual diagram showing the main part of the fifth embodiment. In the fifth embodiment, the blue and green light paths of the fourth embodiment shown in FIG. 10 are exchanged. That is, the blue reflection dichroic mirror 226 is used as the second color separation mirror. Green light and red light are incident on the cross dichroic prism 261 as s-polarized light and reflected by the green reflective film 267 and the red reflective film 266, respectively. The blue light enters the cross dichroic prism 261 as p-polarized light and passes through as it is.

  Further, as described above, the green wavelength region that is incident on the liquid crystal light valve 254 that modulates green light, that is, the green hue, is determined by the selected wavelength region of the blue reflecting dichroic mirror 226 that is the color separation means. The Accordingly, only light in a predetermined wavelength band selected by the blue reflecting dichroic mirror 226 is incident on the green reflecting film 267 of the cross dichroic prism 261. Therefore, even if the reflection band for the green light incident as the s-polarized light of the green reflection film 267 is set to be considerably wider than the predetermined wavelength band to be selected by the dichroic mirror 226, the green hue does not change. On the contrary, it is convenient that the loss of light can be reduced.

  Here, FIG. 12 is a graph showing the spectral reflectance characteristics of the green reflective film 267 used in this embodiment. As can be seen from this graph, the reflection band for the s-polarized light of the green reflecting film 267 used in this embodiment is considerably wider than the wavelength band (usually 500 nm to 580 nm) to be selectively transmitted by the blue reflecting dichroic mirror 226. Is set. However, as described in FIGS. 5 and 6, the reflection band for the s-polarized light of the green reflecting film 267 is set wider than the wavelength band to be selectively transmitted by the blue reflecting dichroic mirror 226. However, since blue light is incident as p-polarized light, the amount of blue light transmitted does not decrease. This is because, as can be seen from the graph of p-polarized light incident shown by the solid line in FIG. 12, the green reflective film 267 transmits most of the wavelength band of blue light incident with p-polarized light (usually about 400 to 500 nm). It is.

  Note that the red reflective film 266 having the characteristics shown in FIG. 5 can be used as it is. Also in this case, as in the case of the green reflective film 267, as shown in FIG. 5, the reflection band for the red light incident as the s-polarized light is considerably wider than the predetermined wavelength band to be selected by the dichroic mirror 210. It can be set to reduce light loss.

  As can be seen from the fourth and fifth embodiments, the cross dichroic prism in the present invention has two reflecting films that respectively reflect two of the three colors of light, and the other one color of light is reflected. What is necessary is just to be comprised so that a cross dichroic prism may pass as it is. However, in the fifth embodiment, the blue light passes through the cross dichroic prism 261 as it is, and the following advantages arise. In general, the color light that passes through the cross dichroic prism as it is has a relatively small amount of reflected light from the cross dichroic prism to the liquid crystal light valve. On the other hand, the color light reflected by the cross dichroic prism passes from the cross dichroic prism to the liquid crystal light valve. There is relatively much reflected light. If the blue light passes through the cross dichroic prism as it is and the green light is reflected as in the fifth embodiment, the reflected light of the blue light is reduced and the reflected light of the green light is increased. By the way, when a high pressure discharge lamp such as a metal halide lamp or a mercury lamp is used as the light source lamp 112, the amount of green light is large. At this time, according to the configuration of the fifth embodiment, since the reflected light of the green light increases, there is an advantage that the balance of the light amounts of the three colors is improved. Further, the light leakage of the polysilicon TFT described above is likely to occur due to reflected light having a short wavelength. In the configuration of the fifth embodiment, the reflected light of blue light, which is the wavelength band on the shortest wavelength side, is reduced. Therefore, even when a polysilicon TFT liquid crystal panel is used, malfunction due to the reflected light from the cross dichroic prism to the light valve. There is an advantage that the possibility of can be reduced.

F. Example 6:
FIG. 13 is a conceptual diagram showing the main part of the sixth embodiment. In the sixth embodiment, in addition to the configuration of the fourth embodiment shown in FIG. 9, a phase difference plate 320 is provided as polarization conversion means on the optical path on the exit side of the cross dichroic prism 260. The position of the phase difference plate 320 is preferably between the cross dichroic prism 260 and the projection lens system 270, but can also be on the exit side of the projection lens system 270.

  As the phase difference plate 320, a λ / 4 phase difference plate, a λ / 2 phase difference plate, or the like can be used. When a λ / 4 retardation plate is used, light of three colors of red, green, and blue can be converted into elliptically polarized light (preferably circularly polarized light). In this way, even when a polarizing screen is used as the projection screen 300 (FIG. 1), a color image can be projected neatly. The polarizing screen is a screen having a function of reflecting only a polarized light component (for example, s-polarized light) in a predetermined polarization direction, preventing reflection of extraneous light, and making an image easy to view. If all three colors of light are made circularly polarized, a color image can be projected neatly using such a polarizing screen.

  When a λ / 2 phase difference plate is used as the phase difference plate 320, the polarization directions of s-polarized light (red light and blue light) and p-polarized light (green light) are changed by about 45 degrees, respectively. It is preferable to determine the direction of the optical axis of the λ / 2 retardation plate. By doing so, the s-polarized light component and the p-polarized light component of the three colors of light are approximately halved, so that a color image can be projected neatly on the polarizing screen.

G. Seventh embodiment:
FIG. 14 is a conceptual diagram showing the main part of the seventh embodiment. In the seventh embodiment, in addition to the configuration of the first embodiment shown in FIG. 4, a λ / 2 phase difference plate 316 is disposed on the optical path between the second dichroic mirror 212 and the liquid crystal light valve 252a. The / 2 phase difference plate 314 is disposed on the optical path between the liquid crystal light valve 252a and the cross dichroic prism 260. Further, the liquid crystal light valve 252a is the same as the liquid crystal light valves 250 and 254. Further, a λ / 2 phase difference plate 320 as a polarization conversion means is disposed on the light path on the emission side of the cross dichroic prism 260.

  The seventh embodiment shows an example in which all the liquid crystal light valves can be made the same, and has almost the same performance as the second embodiment. In the second embodiment, a liquid crystal light valve in which s-polarized light is incident on the liquid crystal light valve is used. In this embodiment, a case in which a liquid crystal light valve in which p-polarized light is incident is used is shown. Yes.

  Note that the λ / 2 phase difference plate 320 as the polarization conversion means disposed behind the cross dichroic prism 260 aims at the same effect as in the sixth embodiment.

H. Example 8:
FIG. 15 is a conceptual diagram showing the main part of the eighth embodiment. The basic configuration of the optical system is the same as that of the second embodiment. In this embodiment, instead of the λ / 2 phase difference plate 312 on the blue light path, two λ / 4 phase difference plates 312a and 312b having the same characteristics constitute the second polarization conversion means. One λ / 4 retardation plate 312a is attached to the polarizing plate 426a, and the other λ / 4 retardation plate 312b is attached to the cross dichroic prism 260. The optical axes of the λ / 4 retardation plates 312a and 312b are such that when p-polarized light emitted from the polarizing plate 426a enters the λ / 4 retardation plate 312a and exits from the λ / 4 retardation plate 312b. It is set so as to be converted into s-polarized light and emitted. For example, the optical axes of the λ / 4 phase difference plates 312a and 312b may be set 45 degrees clockwise with respect to the polarization axis of p-polarized light. By sticking the λ / 4 retardation plate 312b to the cross dichroic prism 260, it is possible to substantially prevent the generation of reflected light at the interface between the air layer and the cross dichroic prism 260. Reflected light is also generated on the incident surface of the λ / 4 retardation plate 312b, but the reflected light is absorbed by the polarizing plate 426a after passing through the λ / 4 retardation plate 312a. As a result, it is possible to prevent malfunction due to light entering from the exit surface side of the liquid crystal panel 422a. Note that the λ / 4 retardation plate 312a is not necessarily attached to the polarizing plate 426a.

  On the green light path, there are two λ / 4 phase difference plates 417a and 417b facing each other between the polarizing plate 416 and the cross dichroic prism 260. Each is attached to the polarizing plate 416 and the cross dichroic prism 260. The optical axes of the λ / 4 phase difference plate 417a and the λ / 4 phase difference plate 417b are inclined by 90 degrees with respect to the optical axis of the λ / 4 phase difference plate 417a. As long as it is set to. In this way, the polarization direction of light becomes elliptically polarized light only between the two λ / 4 retardation plates, and there is no change after passing. In particular, if the optical axes of the two λ / 4 retardation plates 417a and 417b are set to be symmetric by 45 degrees with respect to the polarization axis of the p-polarized light or s-polarized light, the polarization direction becomes two λ / 4. There is no change after passing through the phase difference plate, and it becomes circularly polarized light only in the meantime. By attaching the λ / 4 phase difference plate 417b to the cross dichroic prism 260, generation of reflected light at the interface between the air layer and the cross dichroic prism 260 can be substantially prevented. Reflected light is also generated on the incident surface of the λ / 4 retardation plate 417b, but the reflected light is absorbed by the polarizing plate 416 after passing through the λ / 4 retardation plate 417a. As a result, it is possible to prevent malfunction due to light entering from the exit surface side of the liquid crystal panel 412. Note that the λ / 4 retardation film 417a is not necessarily attached to the polarizing plate 416.

  In the above embodiment, an example in which two λ / 4 phase difference plates are provided between the liquid crystal light valve and the cross dichroic prism has been described. However, two λ / 2 phase difference plates are provided. It may be.

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

(1) In the above embodiment, the two lens arrays 120 and 130 that divide the light of the light source 110 into a plurality of partial light beams are used. However, the present invention is a projection display device that does not use such a lens array. Is also applicable.

(2) The configuration shown in FIGS. 11 and 13, that is, the configuration in which the polarization component adjusting means is provided on the light path on the exit side of the cross dichroic prism 260 is not limited to the sixth embodiment and the seventh embodiment. The present invention can also be applied to the fifth embodiment.

(3) In the above-described embodiment, an example in which the present invention is applied to a transmissive projection display device has been described. However, the present invention can also be applied to a reflective projection display device. Here, “transmission type” means that the light modulation means such as a liquid crystal light valve transmits light, and “reflection type” means that the light modulation means reflects light. It means that there is. In a reflective projection display device, the cross dichroic prism is used as a color light separating means for separating white light into three colors of red, green, and blue, and again synthesizes the modulated three colors of light. It is also used as a color composition unit that emits light in the same direction. Even when the present invention is applied to a reflective projection display device, substantially the same effect as that of a transmissive projection display device can be obtained.

(4) As the projection display device, there are a front projection display device that projects an image from the direction of observing the projection surface and a rear projection display device that projects an image from the side opposite to the direction of observing the projection surface. However, the configuration of the above embodiment can be applied to any of them.

1 is a schematic plan view of a projection display device according to a first embodiment of the present invention. FIG. 3 is a perspective view showing an appearance of a first lens array 120. An explanatory view showing the composition of polarization conversion element. The conceptual diagram which shows the principal part of 1st Example. The graph which shows the spectral reflectance characteristic of a red reflecting film. The graph which shows the spectral reflectance characteristic of a blue reflective film. The figure explaining an example of a polysilicon TFT liquid crystal panel. The conceptual diagram which shows the principal part of 2nd Example. The conceptual diagram which shows the principal part of 3rd Example. The conceptual diagram which shows the principal part of 4th Example. The conceptual diagram which shows the principal part of 5th Example. The graph which shows the spectral reflectance characteristic of the green reflective film in 5th Example. The conceptual diagram which shows the principal part of 6th Example. The conceptual diagram which shows the principal part of 7th Example. The conceptual diagram which shows the principal part of 8th Example. The conceptual diagram which shows the principal part of a projection type display apparatus.

Explanation of symbols

42, 44, 46 ... Liquid crystal light valve 48 ... Cross dichroic prism 50 ... Projection lens system 52 ... Projection screen 61 ... Red reflection film 62 ... Blue reflection film 100 ... Illumination Optical system 110 ... light source 112 ... light source lamp 114 ... concave mirror 120 ... first lens array 122 ... small lens 130 ... second lens array 132 ... small lens 140, DESCRIPTION OF SYMBOLS 140a ... Polarization conversion element 141 ... Polarization beam splitter array 142 ... Selection phase difference plate 143 ... Translucent plate material 144 ... Polarization separation film 145 ... Reflection film 146 ... λ / Two phase difference layers 150 ... Reflective mirror 160 ... Condensing lens 210,212 ... Dichroic mirror 220,222,224 ... Reflective mirror 226 ... Dichroic mirror 230,232 ... Relay lens 240 , 242,244 ... Field lens 250 250a ... first liquid crystal light valve 252,252a ... second liquid crystal light valve 254,254a ... third liquid crystal light valve 260 ... cross dichroic prism 264 ... blue reflective film 266. Red reflection film 267 ... Green reflection film 270 ... Projection lens system 300 ... Projection screen 310, 312, 314, 316 ... λ / 2 phase difference plate 320 ... Phase difference plate 402, 402a ... Liquid crystal panel 404 ... P polarized light transmitting polarizing plate 404a ... s polarized light transmitting polarizing plate 406 ... s polarized light transmitting polarizing plate 406a ... p polarized light transmitting polarizing plate 412, 412a. .. liquid crystal panel 414 ... s polarized light transmitting plate 414a ... p polarized light transmitting polarizing plate 416 ... p polarized light transmitting polarizing plate 416a ... s polarized light transmitting polarizing plate 422,422a ... Liquid crystal panel 424 ... s Polarized light transmission plate 424a ... p Polarized light transmission Polarizing plate for polarizing plate 426 ... Polarizing plate for transmitting polarized light 426a ... Polarizing plate for transmitting polarized light 430 ... Substrate 431 ... Pixel electrode 432 ... Active layer 433 ... Gate insulating layer 434 .. .Gate 435 ... Interlayer insulating film 436 ... Source electrode 440 ... Polarizing plate 450 ... Polysilicon TFT

Claims (4)

A projection display device,
A light source;
First polarization conversion means for converting incident light from the light source into polarized light having a predetermined polarization direction;
Color light separating means for separating light emitted from the first polarization conversion means into three colors of light;
First light modulation means for receiving light of the first color separated by the color light separation means and modulating the light based on a first image signal;
Second light modulation means for receiving light of the second color separated by the color light separation means and modulating the light based on a second image signal;
Third light modulation means for receiving the light of the third color separated by the color light separation means and modulating the light based on a third image signal;
Color synthesizing means for synthesizing the three color lights respectively modulated by the first to third light modulating means and emitting them in the same direction;
A projection optical system that projects the light combined by the color combining means;
Linearly polarized light that is provided on the optical path between the first polarization conversion unit and the color synthesis unit and that has the first color and the third color incident on the color synthesis unit and has a first polarization direction. And at least one of the three color lights so that the second color light incident on the color synthesizing means is linearly polarized light having a second polarization direction orthogonal to the first polarization direction. A second polarization conversion means for adjusting the polarization direction,
The color composition means
A first reflective film for reflecting the light of the first color and a second reflective film for reflecting the light of the third color, which are provided so as to intersect substantially in an X shape; ,
The first polarization conversion means emits linearly polarized light having the first polarization direction,
The first to third light modulators receive linearly polarized light having the first polarization direction as incident light, respectively, and modulate the incident light based on the first to third image signals. To emit linearly polarized light having the second polarization direction,
The second polarization conversion means includes:
Linearly polarized light having the second polarization direction, which is provided on the optical path between the first light modulating unit and the color synthesizing unit and is emitted from the first light modulating unit, is converted into the first polarized light. A first retardation plate that is converted into linearly polarized light having a polarization direction and is incident on the color combining means;
Linearly polarized light having the second polarization direction, which is provided on the optical path between the third light modulating unit and the color synthesizing unit and is emitted from the third light modulating unit, is converted into the first polarized light. A projection display apparatus comprising: a second retardation plate that is converted into linearly polarized light having a polarization direction and is incident on the color synthesizing unit. A projection display device,
A light source;
First polarization conversion means for converting incident light from the light source into polarized light having a predetermined polarization direction;
Color light separating means for separating light emitted from the first polarization conversion means into three colors of light;
First light modulation means for receiving light of the first color separated by the color light separation means and modulating the light based on a first image signal;
Second light modulation means for receiving light of the second color separated by the color light separation means and modulating the light based on a second image signal;
Third light modulation means for receiving the light of the third color separated by the color light separation means and modulating the light based on a third image signal;
Color synthesizing means for synthesizing the three color lights respectively modulated by the first to third light modulating means and emitting them in the same direction;
A projection optical system that projects the light combined by the color combining means;
Linearly polarized light that is provided on the optical path between the first polarization conversion unit and the color synthesis unit and that has the first color and the third color incident on the color synthesis unit and has a first polarization direction. And at least one of the three color lights so that the second color light incident on the color synthesizing means is linearly polarized light having a second polarization direction orthogonal to the first polarization direction. A second polarization conversion means for adjusting the polarization direction,
The color composition means
A first reflective film for reflecting the light of the first color and a second reflective film for reflecting the light of the third color, which are provided so as to intersect substantially in an X shape; ,
The first polarization conversion means emits linearly polarized light having the second polarization direction,
The first to third light modulators receive linearly polarized light having the second polarization direction as incident light, respectively, and modulate the incident light based on the first to third image signals. To emit linearly polarized light having the first polarization direction,
The second polarization conversion means includes:
Provided on an optical path between the second light modulating means and the color synthesizing means for converting the second color light from the first polarization direction into linearly polarized light having the second polarization direction; A projection display device comprising a retardation plate that is incident on the color composition unit. A projection display device,
A light source;
First polarization conversion means for converting incident light from the light source into polarized light having a predetermined polarization direction;
Color light separating means for separating light emitted from the first polarization conversion means into three colors of light;
First light modulation means for receiving light of the first color separated by the color light separation means and modulating the light based on a first image signal;
Second light modulation means for receiving light of the second color separated by the color light separation means and modulating the light based on a second image signal;
Third light modulation means for receiving the light of the third color separated by the color light separation means and modulating the light based on a third image signal;
Color synthesizing means for synthesizing the three color lights respectively modulated by the first to third light modulating means and emitting them in the same direction;
A projection optical system that projects the light combined by the color combining means;
Linearly polarized light that is provided on the optical path between the first polarization conversion unit and the color synthesis unit and that has the first color and the third color incident on the color synthesis unit and has a first polarization direction. And at least one of the three color lights so that the second color light incident on the color synthesizing means is linearly polarized light having a second polarization direction orthogonal to the first polarization direction. A second polarization conversion means for adjusting the polarization direction,
The color composition means
A first reflective film for reflecting the light of the first color and a second reflective film for reflecting the light of the third color, which are provided so as to intersect substantially in an X shape; ,
The first polarization conversion means emits linearly polarized light having the first polarization direction,
The second polarization conversion means includes a first retardation plate provided between the first polarization conversion means and the first to third light modulation means, a second light modulation means, A projection display device, comprising: a second retardation plate provided between the color composition unit.   A projection display device,
  A light source;
  First polarization conversion means for converting incident light from the light source into polarized light having a predetermined polarization direction;
  Color light separating means for separating light emitted from the first polarization conversion means into three colors of light;
  First light modulation means for receiving light of the first color separated by the color light separation means and modulating the light based on a first image signal;
  Second light modulation means for receiving light of the second color separated by the color light separation means and modulating the light based on a second image signal;
  Third light modulation means for receiving the light of the third color separated by the color light separation means and modulating the light based on a third image signal;
  Color synthesizing means for synthesizing the three color lights respectively modulated by the first to third light modulating means and emitting them in the same direction;
  A projection optical system that projects the light combined by the color combining means;
  A second polarization conversion unit that is provided on an optical path between the first polarization conversion unit and the color synthesis unit and adjusts at least one polarization direction of the light of the three colors.
  The color composition means
  A first reflective film for reflecting the light of the first color and a second reflective film for reflecting the light of the third color, which are provided so as to intersect substantially in an X shape; ,
  Each of the first to third light modulators includes an incident-side polarizing plate that transmits light of a specific polarization direction on the light incident side,
  The second polarization conversion unit has the first color incident on the color combining unit, with the light incident on the first to third light modulation units having a polarization direction transmitted through the incident-side polarizing plate. And the third color light is converted into linearly polarized light having a first polarization direction, and the second color light incident on the color combining means has a second polarization direction orthogonal to the first polarization direction. A projection display device comprising at least one retardation plate for linearly polarized light.

Images