JP2010014926A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector that can alleviate the deterioration of the contrast of a projection image while reducing the generation of stray light. <P>SOLUTION: Light resistance and thermal resistance are not only comparatively enhanced but also the generation of stray light due to the reflection is reduced by using absorption type photonic elements 44a, 44b, and 44c as polarization elements. The polarization split property of the photonic element 44a is improved, and the deterioration of the contrast of the projection image due to the insertion of the photonic elements 44a, 44b, and 44c is alleviated, by inclining the photonic elements 44a, 44b, and 44c around the absorption axis AX by a predetermined angle θ (specifically, 0°<θ<45°). Thereby, it is possible to achieve high image quality and high reliability for the projection image of the projector 100. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a projector including a light modulation device.

In a projector of a type incorporating a liquid crystal light valve as a light modulation device, polarizing elements are usually arranged on the incident surface side and the emission surface side of the liquid crystal panel. For example, there is a configuration in which a pre-polarizing plate is used in front of the polarizing plate in order to reduce the thermal load on the polarizing plate on either the incident side or the emission side. The pre-polarizing plate has a transmittance of about 30 to 5 in an orthogonal state from the viewpoint of heat distribution.
0% is common.

As the pre-polarizing plate, an absorptive organic polarizing element is conventionally used in many cases. However, the absorptive organic polarizing element has a problem that it is inferior in light resistance and heat resistance and has a short life.

In order to solve such problems, it is known to improve the light resistance and heat resistance of a polarizing element by using a reflective inorganic polarizing element as a pre-polarizing plate on the incident surface side of the liquid crystal panel. For example, there is one that improves the heat resistance of the polarization separation element by including a polarization separation portion made of an inorganic material, and further improves the contrast of the polarization separation element by providing a plurality of polarization separation portions in the polarization separation element (patent) Reference 1).

In addition, in order to prevent the reflected light from adversely affecting other optical elements, there is one in which a reflective polarizing plate disposed in front of the liquid crystal element is inclined (see, for example, Patent Document 2).
JP 2006-337860 A WO01 / 055778

However, when the pre-polarizing plate as in Patent Document 1 is provided on the exit side of the liquid crystal panel, there is a problem that the light reflected by the reflective inorganic polarizing element affects the liquid crystal panel.

In addition, it is conceivable to apply a method of tilting the reflective polarizing plate as in Patent Document 2 to the exit side of the liquid crystal panel, but it is considered that a problem of stray light due to reflection by the reflective polarizing plate occurs.

SUMMARY An advantage of some aspects of the invention is to provide a projector that can reduce the deterioration of contrast of a projected image while reducing the occurrence of stray light.

In order to solve the above problems, a projector according to the present invention is a projector including a light modulation device that modulates illumination light, and the light modulation device is disposed in a rear stage of the liquid crystal panel and the liquid crystal panel and is emitted from the liquid crystal panel. An absorption type photonic element that extracts a predetermined polarization component from the modulated light, and the photonic element has a continuous mountain-and-valley periodic stacked structure in a direction perpendicular to the periodic direction of the periodic stacked structure. Around the extending axis, it is inclined by a predetermined angle with respect to a reference plane perpendicular to the system optical axis. Here, the photonic element can extract, for example, a linearly polarized light component in a predetermined direction from the modulated light emitted from the liquid crystal panel.

In the projector, by using an absorptive photonic element as a polarizing element, not only light resistance and heat resistance can be made relatively high, but also the generation of stray light due to reflection can be reduced. In addition, by tilting the photonic element by a predetermined angle around an axis extending in a direction perpendicular to the periodic direction, it is possible to reduce deterioration in contrast of the projected image due to simple insertion of the photonic element. As a result, high image quality and high reliability can be realized for the projection image of the projector.

For example, when the photonic element is tilted in the range of 0 ° <θ <45 ° around the absorption axis passing through the system optical axis among the axes extending in the direction perpendicular to the periodic direction with respect to the reference plane, the projected image The contrast degradation can be reduced relatively efficiently.

Further, in a specific aspect or viewpoint of the present invention, the liquid crystal panel is a transmissive image display element that transmits modulated light. In addition, the light modulation device is arranged at the front stage of the liquid crystal panel to selectively extract the linearly polarized light component from the illumination light, and is linearly polarized from the modulated light emitted from the liquid crystal panel arranged at the rear stage of the liquid crystal panel. The photonic device is a pre-polarization device that is disposed between the liquid crystal panel and the second polarization device. In this case, each polarizing element can transmit a polarized light component in a predetermined direction out of the polarized light components of the illumination light, and can be eliminated by reflecting or absorbing other components. Second
Although there is a tendency that a relatively large thermal load is applied to the polarizing element, the thermal load applied to the second polarizing element can be reduced by providing the photonic element before the second polarizing element.

According to another aspect of the present invention, the direction perpendicular to the periodic direction is a direction parallel to the absorption axis of the photonic element, and the absorption axis corresponds to a direction perpendicular to the polarization direction on the exit side. In this case, the photonic element is inclined by a predetermined angle around the absorption axis, and the polarized light can be separated without deteriorating the polarization state. Therefore, it is possible to efficiently extract the linearly polarized light component in the predetermined direction and process the linearly polarized light component other than the predetermined direction with the second polarizing element arranged in the subsequent stage.

According to still another aspect of the present invention, a light source that emits light source light, an illumination optical system that uniformizes the light source light to form illumination light, and illumination light emitted from the illumination optical system for each color light A color separation optical system for separating, a light modulation unit for each color that is illuminated by a light beam of each color light separated by the color separation optical system, on a light path of each color light, and a light modulation device for each color And a projection optical system for projecting the image light that has passed through the synthesis optical system. In this case, it is possible to illuminate each color light modulation device with the corresponding color light, and it is possible to project a high-contrast color image by combining the image light of each color with the combining optical system to form the combined light. .

[First Embodiment]
The structure of the projector according to the first embodiment of the invention will be described below with reference to the drawings.
FIG. 1 is a conceptual diagram for explaining the structure of the projector according to the first embodiment. The projector 100 includes a light source 10, an illumination optical system 20, a color separation optical system 30, and a light modulation unit 40.
A cross dichroic prism 50 and a projection lens 60. Here, the cross dichroic prism 50 and the projection lens 60 embody a composite optical system and a projection optical system, respectively.

In the projector 100, the light source 10 is, for example, a light source device that generates substantially white light having a light quantity sufficient for image light formation, such as a high-pressure mercury lamp, and an arc tube 10a that generates light source light and an arc tube 10a. Reflector 10b having a concave mirror that reflects the light from the light source forward
With.

The illumination optical system 20 includes a collimating lens 22 that is a light collimating unit that collimates the light from the light source, and first and second fly-eye lenses 23a that constitute an integrator optical system for equalizing the light by dividing and superimposing it. , 23b, a polarization conversion element 24 that aligns the polarization direction of light, and a superimposing lens 25 that superimposes light that has passed through both fly-eye lenses 23a, 23b, and forms illumination light. In the illumination optical system 20, the collimating lens 22 converts the luminous flux direction of the illumination light emitted from the light source 10 to be substantially parallel. The first and second fly-eye lenses 23a and 23b are each composed of a plurality of element lenses arranged in a matrix, and the light that has passed through the collimating lens 22 is divided by the element lenses constituting the first fly-eye lens 23a. The light beams are individually condensed, and the divided light beams from the first fly-eye lens 23a are emitted with an appropriate divergence angle by the element lenses constituting the second fly-eye lens 23b. The polarization conversion element 24 is formed of an array having a PBS, a mirror, a retardation plate, etc. as a set of elements, and the polarization direction of each partial light beam divided by the first fly-eye lens 23a is linearly polarized in one direction. It has a role to align. The superimposing lens 25 appropriately converges the illumination light that has passed through the polarization conversion element 24 as a whole, and enables superimposing illumination on the illuminated areas of the liquid crystal light valves 40a, 40b, and 40c, which are the light modulation devices of the subsequent stages.

The color separation optical system 30 includes first and second dichroic mirrors 31a and 31b, reflection mirrors 32a, 32b, and 32c, and three field lenses 33a, 33b, and 33c. Here, as shown in FIG. 1, the first and second dichroic mirrors 31a and 31b are
The optical system is disposed at an angle of approximately 45 degrees with respect to the system optical axis OA extending from the illumination optical system 20.
The color separation optical system 30 converts the illumination light uniformed by the illumination optical system 20 into blue (B), green (G),
And red (R) are separated into three colors, and each color light is separated from the liquid crystal light valves 40a, 40 at the subsequent stage.
b, go to 40c. More specifically, first, the first dichroic mirror 31a is
Of the three colors of BGR, G light and R light are transmitted and B light is reflected. The second dichroic mirror 31b reflects G light and transmits R light out of the two colors of GR. Next, in the color separation optical system 30, the B light reflected by the first dichroic mirror 31 a is reflected by the reflection mirror 3.
The light enters the field lens 33a for adjusting the incident angle through 2a. Further, the G light transmitted through the first dichroic mirror 31a and reflected by the second dichroic mirror 31b is incident on the field lens 33b for adjusting the incident angle. Further, the R light transmitted through the second dichroic mirror 31b is transmitted to the relay lenses LL1 and LL2 and the reflection mirror 3.
The light enters the field lens 33c for adjusting the incident angle through 2b and 32c.

The light modulation unit 40 includes liquid crystal light valves 40a, 40b, and 40c that are light modulation devices for red (R), green (G), and blue (B) colors. Liquid crystal light valve 40a,
Reference numerals 40b and 40c denote non-light-emitting light modulation devices that modulate the spatial distribution of incident illumination light. Among these, the liquid crystal light valve 40a includes a liquid crystal panel 41a illuminated by B light among the respective color lights emitted from the color separation optical system 30, a first polarizing element 42a disposed on the incident side of the liquid crystal panel 41a, A second polarizing element 43a disposed on the emission side of the liquid crystal panel 41a and a photonic element 44a disposed between the liquid crystal panel 41a and the second polarizing element 43a are provided. The liquid crystal panel 41a is, for example, a light transmissive liquid crystal panel (image display element) that operates in a vertical alignment mode.

In the liquid crystal light valve 40a, for example, the first polarizing element 42a transmits light that is to be incident on the liquid crystal panel 41a and transmits linearly polarized light components in a predetermined first direction and reflects components other than linearly polarized light in the first direction. It is a reflective polarizing element. The first polarizing element 42a is usually made of an inorganic material. The second polarizing element 43a is, for example, a light absorption type polarizing element that transmits a linearly polarized component in a predetermined second direction from modulated light emitted from the liquid crystal panel 41a and absorbs a component other than the linearly polarized light in the second direction. is there. The second polarizing element 43a is usually made of an organic material. On the other hand, the photonic element 44a is a light absorption type polarizing element that extracts a linearly polarized light component in the second direction from the modulated light emitted from the liquid crystal panel 41a. The photonic element 44a is made of an inorganic material.

As will be described in detail later, the photonic element 44a is inclined around an absorption axis AX extending in a direction perpendicular to the periodic direction of the periodic multilayer structure with respect to a reference plane perpendicular to the system optical axis OA. Yes.

The other liquid crystal light valves 40b and 40c have the same configuration, and the liquid crystal light valve 40b includes a liquid crystal panel 41b that is illuminated by G light among the respective color lights emitted from the color separation optical system 30, and a liquid crystal panel. The first polarizing element 42b disposed on the incident side of 41b, the second polarizing element 43b disposed on the exit side of the liquid crystal panel 41b, and the photonic disposed between the liquid crystal panel 41b and the second polarizing element 43b. And an element 44b. The liquid crystal light valve 40c includes a liquid crystal panel 41c that is illuminated by R light among the respective color lights emitted from the color separation optical system 30, a first polarizing element 42c that is disposed on the incident side of the liquid crystal panel 41c, and a liquid crystal A second polarizing element 43c disposed on the emission side of the panel 41c, and a photonic element 44c disposed between the liquid crystal panel 41c and the second polarizing element 43c are provided. In the liquid crystal light valves 40b and 40c described above, the photonic elements 44b and 44c are inclined around the absorption axis AX with respect to a reference plane perpendicular to the system optical axis OA.

The B light reflected by the first dichroic mirror 31a enters the liquid crystal light valve 40a via the field lens 33a and the like, and illuminates the liquid crystal panel 41a of the liquid crystal light valve 40a. The G light transmitted through the first dichroic mirror 31a and reflected by the second dichroic mirror 31b enters the liquid crystal light valve 40b via the field lens 33b and the like, and illuminates the liquid crystal panel 41b of the liquid crystal light valve 40b. The R light transmitted through both the first and second dichroic mirrors 31a and 31b is incident on the liquid crystal light valve 40c through the field lens 33c and the like, and illuminates the liquid crystal panel 41c of the liquid crystal light valve 40c.

Each of the liquid crystal panels 41a to 41c modulates the spatial distribution of the polarization state of the incident illumination light.
That is, the three color polarization components respectively incident on the liquid crystal panels 41a to 41c are modulated in accordance with the drive signals or image signals input as electrical signals to the liquid crystal panels 41a to 41c. At this time, the first polarizing elements 42a to 42c adjust the polarization direction of the illumination light incident on the liquid crystal panels 41a to 41c. That is, as described above, the first polarizing elements 42a to 42c.
Each of the polarized light components is eliminated by transmitting the required linearly polarized light component in the first direction (for example, a polarized light component perpendicular to the paper surface) and reflecting the other components. Further, the second polarizing elements 43a to 43c and the photonic elements 44a to 44c are respectively connected to the liquid crystal panels 41a to 41c.
Linearly polarized light component in the second direction of the modulated light emitted from the light source (for example, a polarized light component parallel to the paper surface)
Is extracted as modulated light. With the above, each liquid crystal light valve 40a, 40b, 40c
The image light of each color corresponding to each is formed. The linearly polarized light component in the first direction may be different in the polarization direction of each color light incident on each of the liquid crystal light valves 40a to 40c, but in the present embodiment, all are made to coincide. The angular relationship between the polarization direction of the linearly polarized light component in the first direction and the linearly polarized light component in the second direction is determined by the configuration of the liquid crystal panels 41a to 41c, and the polarization directions of the two are perpendicular to each other. Not necessarily.

The cross dichroic prism 50 combines the image lights of the respective colors from the liquid crystal light valves 40a, 40b, and 40c. More specifically, the cross dichroic prism 50
Has a substantially square shape in plan view in which four right-angle prisms are bonded together, and a pair of dielectric multilayer films 51a and 51b intersecting in an X shape are formed at the interface where the right-angle prisms are bonded together. One first dielectric multilayer film 51a reflects B light and the other second dielectric multilayer film 51b.
Reflects R light. The cross dichroic prism 50 reflects the B light from the liquid crystal light valve 40a by the dielectric multilayer film 51a and emits it to the right in the traveling direction, so that the liquid crystal light valve 4
The G light from 0b goes straight and is emitted through the dielectric multilayer films 51a and 51b, and the R light from the liquid crystal light valve 40c is reflected by the dielectric multilayer film 51b and emitted to the left in the traveling direction. In this way, the B light, the G light, and the R light are combined by the cross dichroic prism 50 to form combined light that is color image light.

The projection lens 60 enlarges the image light by the combined light formed through the cross dichroic prism 50 at a desired magnification and projects a color image on a screen (not shown). That is, a color moving image or a color still image with a desired magnification corresponding to the drive signal or image signal input to each of the liquid crystal panels 41a to 41c is projected on the screen.

2A and 2B show liquid crystal light valves 40a and 4 constituting the light modulation unit 40 of FIG.
FIG. 4 is a side view and a plan view conceptually illustrating an example of a liquid crystal light valve 40a arranged on the first optical path OP1 among 0b and 40c. That is, FIG. 2A, which is a side view, is a view of the liquid crystal light valve 40a of FIG. 1 as viewed from the left side surface in the traveling direction (z-axis direction) of the optical path. FIG. 2B which is a plan view corresponds to FIG.

As described above, the liquid crystal light valve 40a includes the liquid crystal panel 41a and the first polarizing element 42a.
And a second polarizing element 43a and a photonic element 44a. As can be seen from FIG. 2B, the photonic element 44a has the first optical path OP of the system optical axis OA in FIG.
1 is inclined with respect to an absorption axis AX parallel to the y-axis with reference to an xy plane perpendicular to the system optical axis OA on 1. Hereinafter, the structure and arrangement of the photonic element 44a will be described more specifically.

As can be seen from FIGS. 2A and 2B, the photonic element 44a has a structure in which, for example, SiO ₂ having a refractive index different from each other on a quartz substrate P1 having grooves periodically provided in one direction.
A periodic structure portion P2 having a periodic composition structure in which layers LY1 and Nb ₂ O ₅ layers LY2 are alternately stacked in the depth direction (intermediate layers are omitted in FIGS. 2A and 2B) It is provided. By having such a structure, the photonic element 44a has a periodic uneven structure in a one-dimensional manner with respect to the axis of the periodic direction of the photonic element 44a on the quartz substrate P1, that is, the direction along the transmission axis TX. A fine valley-like multilayer structure having a desired film thickness and angle is formed in the periodic structure portion P2. An axis perpendicular to the periodic direction along the transmission axis TX and parallel to the y-axis direction is an absorption axis AX. That is, the transmission axis TX and the absorption axis AX are in a perpendicular relationship. The period of the periodic structure portion P2 of the photonic element 44a is set to be smaller than the wavelength of incident light. By adjusting the material and period of the periodic structure portion P2, a desired refractive index distribution and optical anisotropy can be realized, and as a result, a desired polarization characteristic can be realized. Here, the photonic element 44a exhibits designed characteristics for light incident on the inclined portion of the periodic structure portion P2 along the normal direction I of the entire photonic element 44a. But,
The photonic element 44a is generally considered to have a significantly deteriorated oblique incidence characteristic because the light decomposition direction shifts with respect to obliquely incident light other than the normal direction I. However, the inventor of the present application has found that, as will be described in detail later, when the photonic element 44a is tilted in an appropriate direction, deterioration of the characteristics can be effectively suppressed.

In the present embodiment, in particular, the quartz substrate P1 is positioned on the incident side of the B light, and the periodic structure portion P
2 is located on the B light emission side. Thereby, it is possible to maintain good absorption / transmission characteristics by utilizing the characteristics on the surface side of the periodic structure portion P2.

Here, as described above, the photonic element 44a is inclined with respect to the reference plane perpendicular to the system optical axis OA on the optical path of the first optical path OP1 in the system optical axis OA. As can be seen from FIG. 2B and the like, a predetermined angle θ (0 ° <θ <4) around the absorption axis AX parallel to the y-axis direction of the photonic element 44a with respect to the xy plane perpendicular to the system optical axis OA.
5 °) arranged at a rotated position. In contrast, the incident surface of the liquid crystal panel 41a is the first.
It faces the xy plane perpendicular to the system optical axis OA of the optical path OP1. Therefore, the incident surface of the photonic element 44a and the exit surface of the liquid crystal panel 41a face each other in a state where they are not parallel. In other words, the normal to the exit surface of the liquid crystal panel 41a is equal to the direction of the system optical axis OA of the first optical path OP1 and equal to the z direction, whereas the normal to the incident surface of the photonic element 44a is z The two directions are inclined and face each other.

FIG. 3 is a diagram for explaining the evaluation of the angle characteristics of the liquid crystal panel 41a. FIG.
FIG. 3B shows a projection image when the photonic element 44a is not inserted, and FIG. 3B shows a projection image when the photonic element 44a is inserted. The projected image is a state in which the projection lens is removed. In the projected image of FIG. 3A, the incident light is substantially uniform from any direction. On the other hand, in the projected image of FIG. 3B, the incident light from the oblique direction has increased.
From the above, it can be seen that the photonic element 44a has a relatively large incident angle dependency and wavelength dependency and affects the contrast of the projected image.

4 and 5 are diagrams for explaining the influence on the contrast of the projected image when the photonic element 44a is disposed between the liquid crystal panel 41a and the second polarizing element 43a. FIG. 4A shows a state where the photonic element 44a is not tilted (hereinafter referred to as “PP0 °”).
(B) is a state in which the photonic element 44a is tilted 20 degrees around the absorption axis AX (hereinafter referred to as “P
A20 ". 4C shows a state in which the photonic element 44a is tilted by 20 degrees around the transmission axis TX (hereinafter referred to as “PT20 °”). FIG. 5A shows a state where the photonic element 44a is not inserted (hereinafter referred to as “no PP”) and FIG.
) To (C) show the black illuminance of the projected image. FIG. 5B is an enlarged view of FIG. 5A, and FIG. 5C shows the position of the measurement point. 5 (A), 5 (B)
, The horizontal axis is the measurement point, and the vertical axis is the illuminance, and the measurement point is the central portion of each area when the screen is divided into 3 × 3 areas. 5A and 5B correspond to the state without PP, the diamond (♦) mark corresponds to the state of PA 20 °, and the triangle (▲) mark indicates PP0 °.
The square (■) mark corresponds to the PT 20 ° state.

As can be seen from FIGS. 5 (A) and 5 (B), in the PT 20 ° state, the illuminance is higher than in other states, and the contrast is significantly reduced. On the other hand, in the state of PA 20 °, the illuminance is lower than in the state of PP 0 °, and the influence on the contrast due to the insertion of the photonic element 44a is reduced. That is, when the photonic element 44a is added, the contrast, which has been considered to deteriorate more than the state without the photonic element 44a, is reduced by rotating the photonic element 44a around the absorption axis AX. You can see that

The above describes the case where the inclination angle θ is 20 °, but the photonic element 44a is
Installation is possible even when the inclination angle θ is 0 ° <θ <45 °. However, if it exceeds 45 °, the deterioration of the contrast becomes large and it becomes impractical.

Returning to FIG. 1, along the order of the optical path of B light, which is one of the illumination lights, the liquid crystal light valve 40a.
The operation of will be specifically described.

First, the B light separated by the color separation optical system 30 in FIG. 1 enters the first polarizing element 42a of the liquid crystal light valve 40a along the first optical path OP1 as illumination light in FIG. First
As described above, the polarizing element 42a transmits the linearly polarized light component in the first direction and reflects components other than the linearly polarized light in the first direction. More specifically, the first polarizing element 42a transmits S-polarized light in a direction perpendicular to the paper surface of FIG. 1 among polarized light components of B light, and reflects P-polarized light parallel to the paper surface. Next, the B light transmitted through the first polarizing element 42a is the liquid crystal panel 4 as described with reference to FIG.
The linearly polarized light component in the second direction is extracted by the photonic element 44a. More specifically, the photonic element 44a has a modulated B
Of the light, P-polarized light parallel to the paper surface of FIG. 1 is transmitted, while S-polarized light perpendicular to the paper surface is absorbed. Similarly, the second polarizing element 43a transmits P-polarized light parallel to the paper surface of FIG. 1 among the modulated B light, and absorbs S-polarized light perpendicular to the paper surface.

In the description of the present embodiment, the structure, function, etc. of the liquid crystal light valve 40a corresponding to B light that is color light including the ultraviolet or blue light wavelength range have been described. The same applies to the structure and function of the liquid crystal light valves 40b and 40c.

In the projector 100 described above, an absorptive photonic element 44 is used as a polarizing element.
By using a, 44b, and 44c, not only light resistance and heat resistance can be made relatively high, but also the generation of stray light due to reflection can be reduced. Further, the photonic elements 44a, 44b, 44c are moved around the absorption axis AX by a predetermined angle θ (specifically, 0 ° <θ <45).
By tilting only by (°), the polarization separation characteristics of the photonic element 44a can be improved, and deterioration of the contrast of the projected image due to the insertion of the photonic elements 44a, 44b, 44c can be reduced. As a result, high image quality and high reliability can be realized for the projection image of the projector 100.

The second polarizing elements 43a, 43b, 43c and the photonic elements 44a, 44b, 44
In addition to transmitting the linearly polarized light component in the second direction among the polarized light components of the modulated light emitted from the liquid crystal panels 41a, 41b, and 41c by c, it can be eliminated by absorbing the other components. Further, although there is a tendency that a relatively large thermal load is applied to the second polarizing element, the second polarizing element is provided by providing the photonic elements 44a, 44b, 44c in front of the second polarizing elements 43a, 43b, 43c. The thermal load applied to 43a, 43b, and 43c can be reduced.

[Second Embodiment]
Hereinafter, a projector according to a second embodiment of the invention will be described. The projector according to the second embodiment is a modification of the projector according to the first embodiment. Portions that are not particularly described are the same as those in the first embodiment, and redundant description is omitted.

FIG. 6 is a diagram illustrating the configuration of the optical system of the projector according to the second embodiment.
The projector 200 includes a light source 210, an illumination optical system 220, a color separation optical system 230,
A light modulation unit 240, a cross dichroic prism 250, and a projection lens 260 are provided.

The light modulation unit 240 includes liquid crystal panels 241a, 241b, and 241c, polarizing beam splitters 243a, 243b, and 243c, and photonic elements 244a, 244b, and 244c. Here, the liquid crystal panel 241a, the polarization beam splitter 243a, and the photonic element 244a constitute a liquid crystal light valve 240a for B color for two-dimensionally modulating the B light of the image light based on image information. To do. Similarly, the liquid crystal panel 241b, the polarization beam splitter 243b, and the photonic element 244b are also used for the G color liquid crystal light valve 240.
b, the liquid crystal panel 241c, the polarization beam splitter 243c, and the photonic element 2
44c also constitutes an R color liquid crystal light valve 240c. Note that the liquid crystal panel 241a,
Reference numerals 241b and 241c denote light reflective liquid crystal panels (image display elements) that change the polarization direction of incident light in units of pixels in accordance with an input signal.

More specifically, in the liquid crystal light valve 240a, the polarizing beam splitter 24 is used.
3a is provided in place of the first and second polarizing elements 42a and 43a of FIG. 1, and includes a polarization direction of light incident on the liquid crystal panel 241a and a polarization direction of light emitted from the liquid crystal panel 241a. Have made adjustments. The polarization beam splitter 243a incorporates a polarization separation film 3a for separating polarized light.

The polarization beam splitter 243a reflects the S-polarized light in the direction perpendicular to the plane of FIG. 6 of the incident light by the polarization separation film 3a so as to enter the liquid crystal panel 241a, and the polarized light out of the modulated light emitted from the liquid crystal panel 241a. P-polarized light in a direction parallel to the paper surface passing through the separation membrane 3a is emitted.

The photonic element 244a is provided at the subsequent stage of the polarization beam splitter 243a, and has a predetermined angle θ around an absorption axis AX parallel to the y-axis direction of the photonic element 244a with respect to the xy plane perpendicular to the system optical axis OA on the exit side. (Specifically, it is arranged at a position rotated by 0 ° <θ <45 °).

The photonic element 244a transmits the P-polarized light transmitted through the polarization beam splitter 243a.
The same applies to the liquid crystal light valves 240b and 240c.

As shown in FIG. 7, the liquid crystal light valve 240a transmits incident light through the polarization beam splitter 343a, enters the liquid crystal panel 341a, and reflects the modulated light emitted from the liquid crystal panel 341a by the polarization separation film 4a. Then, the light may enter the photonic element 344a. In this case, the polarization beam splitter 343a transmits the P-polarized light in the incident light,
Of the modulated light emitted from the liquid crystal panel 341a by the polarization separation film 4a, S-polarized light is reflected and emitted.

The photonic element 344a is provided at a subsequent stage of the polarization beam splitter 343a, and has a predetermined angle θ around an absorption axis AX parallel to the x-axis direction of the photonic element 344a with respect to the xy plane perpendicular to the system optical axis OA on the emission side. (Specifically, it is arranged at a position rotated by 0 ° <θ <45 °). The photonic element 344a transmits the S-polarized light transmitted through the polarization beam splitter 343a.
The same applies to other liquid crystal light valves.

Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and can be implemented in various modes without departing from the gist thereof. Such modifications are also possible.

In the above embodiment, the liquid crystal light valves 40a to 40c and 240a to 240c are provided with the photonic elements 44a to 44c and 244a to 244c.
You may provide a photonic element only in some of 0a-40c and 240a-240c. For example, a mode in which only the photonic element 44a corresponding to the B light that is considered to contain the largest number of wavelengths in the ultraviolet light region, which is a cause of deterioration of the optical device, is conceivable.

1 and 6, the photonic elements 44a to 44c and 244a to 244c are
It is assumed that the photonic element 44 is tilted counterclockwise from a position perpendicular to the paper surface.
It is also possible to tilt clockwise according to the polarization state of each color light incident on a to 44c and 244a to 244c.

In the above embodiment, the photonic elements 44a to 44c and 244a to 244c are configured such that the quartz substrate P1 is located on the light incident side and the periodic structure portion P2 is located on the light emission side. The photonic elements 44a to 44c and 244a to 244c in which the quartz substrate P1 is located on the light emission side are also applicable. With respect to this positional relationship, the incident direction is generally selected at the element design stage, and either can be selected.

In the above embodiment, an example of the projector 100 using the three liquid crystal light valves 40a to 40c has been described. However, the present invention is a projector using only one liquid crystal light valve, and a projector using two liquid crystal light valves. Alternatively, the present invention can be applied to a projector using four or more liquid crystal light valves.

In the above embodiment, the light sources 10 and 210 are high-pressure mercury lamps, but other lamps such as metal halide lamps may be used instead of the high-pressure mercury lamp.

In the above embodiment, the light modulation device is not limited to a liquid crystal panel or the like, and may be a light modulation device using a micromirror, for example.

In the above embodiment, only an example of a front type projector that projects from the direction of observing the screen has been described, but the present invention is also applicable to a rear type projector that projects from the side opposite to the direction of observing the screen. Is possible.

It is a conceptual diagram for demonstrating the projector which concerns on 1st Embodiment. (A) is a side view for demonstrating an example of the liquid crystal light valve of FIG. 1, (B) is the top view. (A), (B) is a figure explaining angle characteristic evaluation of the liquid crystal panel of FIG. (A), (B), (C) is a figure explaining arrangement | positioning of a photonic element. (A), (B), (C) is a figure explaining the black illuminance of a projection image. It is a conceptual diagram for demonstrating the projector which concerns on 2nd Embodiment. It is a figure explaining the modification of the liquid crystal light valve of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100, 200 ... Projector, 10, 210 ... Light source, 20, 220 ... Illumination optical system, 30, 230 ... Color separation optical system, 40, 240 ... Light modulation part, 40a, 40b, 40
c, 240a, 240b, 240c, 340a ... liquid crystal light valve, 41a, 41b,
41c, 241a, 241b, 241c, 341a ... Liquid crystal panel, 42a, 42b, 4
2c ... 1st polarizing element, 43a, 43b, 43c ... 2nd polarizing element, 243a, 243b
243c, 343a ... polarizing beam splitter, 44a, 44b, 44c, 244a,
244b, 244c, 344a ... Photonic element, 50, 250 ... Cross dichroic prism, 60, 260 ... Projection lens

Claims (6)

A projector comprising a light modulation device for modulating illumination light,
The light modulation device includes a liquid crystal panel, and an absorption photonic element that is arranged at a rear stage of the liquid crystal panel and extracts a predetermined polarization component from the modulated light emitted from the liquid crystal panel,
The photonic element has a continuous mountain-valley-like periodic laminated structure, and is inclined by a predetermined angle with respect to a reference plane perpendicular to the system optical axis about an axis extending in a direction perpendicular to the periodic direction of the periodic laminated structure. A projector. The projector according to claim 1, wherein the photonic element extracts a linearly polarized light component in a predetermined direction from the modulated light emitted from the liquid crystal panel. The photonic element is inclined with respect to the reference plane in a range of 0 ° <θ <45 ° around an absorption axis passing through the system optical axis among axes extending in a direction perpendicular to the periodic direction. The projector as described in any one of Claim 1 and Claim 2. The projector according to any one of claims 1 to 3, wherein the liquid crystal panel is a transmissive image display element that transmits modulated light. The light modulator includes a first polarizing element that is disposed in front of the liquid crystal panel and selectively extracts linearly polarized light components from the illumination light, and modulated light that is disposed in the rear stage of the liquid crystal panel and emitted from the liquid crystal panel. 5. A second polarizing element that selectively extracts a linearly polarized light component from the first polarizing element, wherein the photonic element is a pre-polarizing element disposed between the liquid crystal panel and the second polarizing element. Projector. A light source that emits light source light;
An illumination optical system that uniformizes the light source light to form illumination light;
A color separation optical system that separates the illumination light emitted from the illumination optical system into each color light;
A light modulation unit having the light modulation device for each color that is illuminated by a light beam of each color light separated by the color separation optical system on an optical path of each color light; and
A combining optical system that combines the image light of each color emitted from the light modulation device of each color;
A projection optical system for projecting image light that has passed through the synthetic optical system;
The projector according to any one of claims 1 to 5, further comprising:

Images