JP2010085559A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector which displays a high-quality image with compact and simple constitution. <P>SOLUTION: The projector includes: transmissive liquid crystal panels 20R, 20G and 20B being a plurality of spatial light modulation elements which modulate light according to an image signal; a cross dichroic prism 27 being a color synthesizing optical element which synthesizes the light modulated by the plurality of spatial light modulation elements; a condensing means provided at a position on which the light modulated by the spatial light modulation elements is made incident and having condensing action to condense light; and a diverging means provided at a position on which light to be synthesized by the color synthesizing optical element is made incident and having diverging action to diverge light. The projector has at least either convex parts formed on emitting surfaces of the spatial light modulation elements from which the light is emitted and functioning as the condensing means or concave parts formed on incident surfaces of the color synthesizing optical element on which the light to be synthesized is made incident and functioning as the diverging means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a projector, and more particularly to a technology of a projector that synthesizes and projects a plurality of color lights modulated according to an image signal.

Conventional projectors employ a configuration in which light emitted from an illumination optical system is collimated and incident on a spatial light modulator. The light modulated by the spatial light modulator provided for each color light is synthesized by the color synthesis optical element and projected by the projection lens. The size of the illumination optics,
When the optical characteristics such as the condensing characteristic are determined, the diameter of the lens (rear lens) arranged at the farthest position from the projection plane among the plurality of lenses constituting the projection lens is determined. For this reason, the conventional projector has a problem that it is difficult to reduce the size of the projection lens. As a technique for reducing the size of a projection lens, for example, in Patent Document 1, a condenser lens is provided between a spatial light modulation element and a color synthesis optical element, and light modulated by the spatial light modulation element is projected. Techniques for focusing on the entrance pupil of the lens have been proposed. Patent Document 2 proposes a technique for arranging a color synthesizing optical element between lenses constituting a projection lens.

JP 2002-31845 A JP 2000-35612 A

In a configuration in which the light is condensed on the entrance pupil of the projection lens using a condensing lens, the incident angle to the color combining optical element (the angle formed by the principal ray with respect to the optical axis) is increased by providing the condensing lens. It becomes. Since the wavelength selection characteristics of the dichroic film provided in the color synthesis optical element depend on the incident angle of light, the selection wavelength of the dielectric multilayer film shifts from the desired wavelength as the angle of incidence on the color synthesis optical element changes. Will be. When the selection wavelength in the dichroic film changes partially, there arises a problem that the color unevenness of the image is caused and the quality of the image is lowered. If such a correction means for correcting the shift of the selected wavelength is required for the color synthesizing optical element, the manufacturing cost of the color synthesizing optical element increases. In addition, in the configuration in which the color combining optical element is disposed between the lenses constituting the projection lens, an increase in the incident angle to the color combining optical element can be suppressed, while the space light modulating element and the color combining optical element are interposed. A lens to be arranged is required for each color light. For this reason, the number of lenses required for the projector is increased, causing a problem that the configuration of the projector becomes large and complicated. The present invention has been made in view of the above-described problems, and an object thereof is to provide a projector that can display a high-quality image with a small and simple configuration.

In order to solve the above-described problems and achieve the object, a projector according to the present invention includes a plurality of spatial light modulation elements that modulate light according to an image signal, and light modulated by the plurality of spatial light modulation elements. Color combining optical element to be combined, light condensing means for condensing light that is provided at the position where light modulated by the spatial light modulation element is incident, and light to be combined by the color combining optical element are incident And a diverging means having a diverging action for diverging light, and a convex surface portion that is formed on an exit surface that emits modulated light of the spatial light modulation element and functions as a condensing means. The color combining optical element has at least one of a concave surface portion that is formed on an incident surface on which light to be combined is incident and functions as a diverging unit.

By condensing light by the condensing means, the projection lens can be miniaturized. Also,
By making the light condensed by the condensing means enter the diverging means, the direction of the light is changed so that the angle formed by the chief ray with respect to the optical axis is reduced, and the selection in the dichroic film of the color synthesis optical element Reduce wavelength shift. By reducing the change in the selection wavelength in the dichroic film, it is possible to display an image with little color unevenness without using a correction unit. Furthermore, by having a configuration having at least one of a convex surface portion functioning as a condensing means and a concave surface portion functioning as a diverging means, the number of parts of the projector can be reduced as compared with a configuration in which a condensing lens and a diverging lens are separately provided. The projector can be made small and simple. Thereby, a projector capable of displaying a high-quality image with a small and simple configuration can be obtained.

Moreover, as a preferable aspect of the present invention, it is desirable to have a convex surface portion formed in the spatial light modulator and a concave surface portion formed in the color synthesis optical element. As a result, neither the condenser lens nor the diverging lens can be required, and the projector can be made smaller and simpler.

Moreover, as a preferable aspect of the present invention, it is desirable that the diverging unit collimates the light incident from the condensing unit. Thereby, the shift of the selection wavelength in the dichroic film | membrane of a color synthetic | combination optical element can further be reduced, and a still higher quality image can be displayed.

Moreover, as a preferable aspect of the present invention, it is desirable that the rear focal point of the light collecting unit and the front focal point of the diverging unit substantially coincide. Thereby, the collimated light incident on the light collecting means can be condensed by the light collecting means and then collimated by the diverging means.

As a preferred aspect of the present invention, the spatial light modulation element is a transmissive liquid crystal panel, and the convex surface portion is provided on an emission side substrate provided on the side of the transmissive liquid crystal panel that emits modulated light. It is desirable to be formed. Thereby, the light modulated by the transmissive liquid crystal panel can be condensed.

In a preferred aspect of the present invention, the first spatial light modulator that modulates the first color light is used.
A spatial light modulator, a second spatial light modulator that is a spatial light modulator that modulates the second color light, and a third spatial light modulator that is a spatial light modulator that modulates the third color light, The color synthesizing optical element includes a first concave surface portion which is a concave surface portion formed on an incident surface on which the first color light modulated by the first spatial light modulation device is incident, and a second concave portion modulated by the second spatial light modulation device. A second concave surface portion that is a concave surface portion formed on the incident surface on which the colored light is incident, and a third concave surface portion that is a concave surface portion formed on the incident surface on which the third color light modulated by the third spatial light modulator is incident. It is desirable to have. As a result, the first
The color light, the second color light, and the third color light have little color unevenness, and a high-quality image can be displayed.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of a projector 10 according to Embodiment 1 of the present invention. Projector 1
Reference numeral 0 denotes a front projection type projector that projects light onto the screen 29 and observes the image by observing the light reflected by the screen 29. The light source unit 11 is, for example, an ultra high pressure mercury lamp. The light source unit 11 emits light including red (R) light, green (G) light, and blue (B) light.

The first integrator lens 12 and the second integrator lens 13 have a plurality of lens elements arranged in an array. The first integrator lens 12 divides the light beam from the light source unit 11 into a plurality of parts. Each lens element of the first integrator lens 12 condenses the light beam from the light source unit 11 in the vicinity of the lens element of the second integrator lens 13. The lens element of the second integrator lens 13 forms an image of the lens element of the first integrator lens 12 on the spatial light modulation element.

The polarization conversion element 14 converts light that has passed through the two integrator lenses 12 and 13 into specific linearly polarized light. The superimposing lens 15 superimposes the image of each lens element of the first integrator lens 12 on the spatial light modulation element. The first integrator lens 12, the second integrator lens 13, and the superimposing lens 15 make the light intensity distribution from the light source unit 11 uniform on the spatial light modulator. The light source unit 11, the first integrator lens 12, the second integrator lens 13, the polarization conversion element 14, and the superimposing lens 15 constitute an illumination optical system.

The reflection mirror 16 bends the optical path of the light from the superimposing lens 15 by reflection. The first dichroic mirror 17 transmits R light out of the light from the reflection mirror 16, and transmits G light and B light.
Reflects light. The reflection mirror 18 reflects R from the first dichroic mirror 17 by reflection.
Bend the light path. The R light field lens 19R collimates the R light from the reflection mirror 18 and enters the R light transmissive liquid crystal panel 20R.

The R light transmissive liquid crystal panel 20R functions as a first color light spatial light modulator that modulates R light, which is first color light, in accordance with an image signal. The condensing lens 21R for R light is a convex lens that functions as a condensing means for R light. The convex lens has a light collecting function for collecting light. R
The light condensing lens 21R is a position where light modulated by the R light transmissive liquid crystal panel 20R enters, and is provided in the optical path between the R light transmissive liquid crystal panel 20R and the cross dichroic prism 27. ing.

The second dichroic mirror 22 reflects the G light from the first dichroic mirror 17 and transmits the B light. The G light field lens 19G includes a second dichroic mirror 22.
The G light from the light is collimated and is incident on the transmissive liquid crystal panel 20G for G light. The G light transmissive liquid crystal panel 20G functions as a second color light spatial light modulation element that modulates the G light, which is the second color light, in accordance with an image signal. The G light condensing lens 21G is a convex lens that functions as a condensing means for G light. The G light condensing lens 21G is a position where the light modulated by the G light transmissive liquid crystal panel 20G is incident, and is provided in the optical path between the G light transmissive liquid crystal panel 20G and the cross dichroic prism 27. It has been.

The relay lenses 23 and 25 are provided in the optical path between the second dichroic mirror 22 and the reflection mirror 24 and in the optical path between the reflection mirror 24 and the reflection mirror 26, respectively. B
Since the optical path of the light is longer than the optical path of the R light and the optical path of the G light, relay lenses 23 and 25 are used in the optical path of the B light in order to make the illumination magnification in the spatial light modulation element equal to that of other color lights. A relay optical system is adopted. The reflection mirrors 24 and 26 bend the optical path of the B light by reflection.

The B light field lens 19B collimates the B light from the reflection mirror 26 and makes it incident on the B light transmissive liquid crystal panel 20B. The transmissive liquid crystal panel 20B for B light has a third color light B
It functions as a spatial light modulator for third color light that modulates light according to an image signal. The condensing lens 21B for B light is a convex lens that functions as a condensing means for B light. The condensing lens 21B for B light is a position where light modulated by the transmissive liquid crystal panel 20B for B light is incident,
It is provided in the optical path between the light transmission type liquid crystal panel 20 </ b> B and the cross dichroic prism 27.

In the transmissive liquid crystal panels 20R, 20G, and 20B, a liquid crystal layer for modulating light according to an image signal is sealed between two substrates made of a transparent member. Transmission type liquid crystal panel 20R, 2
As 0G and 20B, for example, a high-temperature polysilicon TFT liquid crystal panel (High Temperatur
e Polysilicon (HTPS) is used. The transmission type liquid crystal panels 20R, 20G, 20B
A polarizing filter (not shown) that transmits a specific linearly polarized light is provided on the incident side and the exit side of the light. The cross dichroic prism 27 is configured to transmit the R light modulated by the transmissive liquid crystal panel 20R for R light, the G light modulated by the transmissive liquid crystal panel 20G for G light, and the transmissive liquid crystal panel 2 for B light.
It functions as a color synthesizing optical element that synthesizes B light modulated by 0B. The projection lens 28 projects the light combined by the cross dichroic prism 27 toward the screen 29.

FIG. 2 shows a perspective configuration of the cross dichroic prism 27. The cross dichroic prism 27 is configured by bonding four prisms made of a transparent member. First
The dichroic film 31 and the second dichroic film 32 are provided between the prisms. The first dichroic film 31 and the second dichroic film 32 are arranged so as to be substantially orthogonal to each other. The first dichroic film 31 reflects R light and transmits G light and B light. The second dichroic film 32 reflects B light and transmits R light and G light. First
The dichroic film 31 and the second dichroic film 32 are, for example, dielectric multilayer films.

The first concave surface portion 33 is formed on the incident surface of the cross dichroic prism 27 on which the R light modulated by the R light transmissive liquid crystal panel 20R is incident. The first concave surface portion 33 is provided at a position where the R light synthesized by the cross dichroic prism 27 is incident. First
The concave portion 33 is a concave curved surface having a curvature in the two-dimensional direction, and has a diverging action for diverging light. The first concave surface portion 33 functions as a diverging unit for R light.

The second concave surface portion 34 is formed on the incident surface of the cross dichroic prism 27 on which the G light modulated by the transmissive liquid crystal panel 20G for G light is incident. The second concave surface portion 34 is provided at a position where G light to be synthesized by the cross dichroic prism 27 is incident. Second
Similar to the first concave surface portion 33, the concave surface portion 34 is a concave curved surface having a curvature in the two-dimensional direction, and has a diverging action for diverging light. The second concave surface portion 34 functions as a diverging unit for G light.

The third concave surface portion 35 is formed on an incident surface of the cross dichroic prism 27 on which the B light modulated by the B light transmissive liquid crystal panel 20B is incident. The third concave surface portion 35 is provided at a position where B light to be combined by the cross dichroic prism 27 is incident. Third
Similar to the first concave surface portion 33 and the second concave surface portion 34, the concave surface portion 35 is a concave curved surface having a curvature in the two-dimensional direction and has a diverging action for diverging light. The third concave surface portion 35 functions as a diverging unit for B light. The first concave surface portion 33, the second concave surface portion 34, and the third concave surface portion 3
5 may be either spherical or aspherical.

Out of the cross dichroic prism 27, the exit surface 36 for emitting each color light is a substantially flat surface. The concave surface portions 33, 34, and 35 are formed, for example, by polishing the surface of the prism. The cross dichroic prism 27 has concave surface portions 33, 34, 35.
Are formed by combining the three prisms formed with a single prism having a plane serving as the exit surface 36.

FIG. 3 is a conceptual diagram illustrating the operation of the condenser lens and the concave surface portion. Here, the condenser lens 21R for R light and the first concave surface portion 33 are shown and described. The rear focal point of the R light condensing lens 21 </ b> R and the front focal point of the first concave surface portion 33 substantially coincide with each other. The parallel light whose principal ray is substantially parallel to the optical axis AX is condensed toward the focal point by passing through the R light condenser lens 21R, and then again through the first concave surface portion 33. Parallelized. Condensing lens 21 for G light
The G and second concave surface portions 34, the B light condensing lens 21B and the third concave surface portion 35 are configured in the same manner as the R light condensing lens 21R and the first concave surface portion 33.

By condensing light by the condensing lenses 21R, 21G, and 21B, the projection lens 28 is obtained.
Can be miniaturized. The light condensed by the condensing lenses 21R, 21G, and 21B is converted into parallel light again by the concave surface portions 33, 34, and 35, thereby reducing the shift of the selection wavelength in the dichroic films 31 and 32. By reducing the change in the selection wavelength in the dichroic films 31 and 32, it is possible to display an image with little color unevenness without using correction means.

By forming concave surface portions 33, 34, 35 on the cross dichroic prism 27,
The number of parts of the projector 10 can be reduced as compared with a configuration in which a diverging lens is separately provided, and the projector 10 can have a simple configuration and can be downsized. Thereby, there is an effect that a high-quality image can be displayed with a small and simple configuration.

The rear focal points of the condenser lenses 21R, 21G, and 21B and the front focal points of the concave surface portions 33, 34, and 35 are not limited to coincide. Even if the rear focal points of the condenser lenses 21R, 21G, and 21B and the front focal points of the concave surface portions 33, 34, and 35 do not coincide with each other, the concave surface is formed so that the angle formed by the principal ray with respect to the optical axis AX becomes small. If the light traveling direction can be changed by the portions 33, 34, and 35, it is possible to obtain an effect of reducing the shift of the selection wavelength in the dichroic films 31 and 32.

The projector 10 according to the present embodiment is not limited to the case where a transmissive liquid crystal panel is used as the spatial light modulation element. As the spatial light modulator, a reflective liquid crystal display device (Liquid Crystal O
n Silicon (LCOS), DMD (Digital Micromirror Device), GLV (Grating)
Light Valve) or the like may be used.

FIG. 4 shows a schematic configuration of the projector 40 according to the second embodiment of the invention. The projector 40 according to the present embodiment has concave surface portions 33 and 34 formed on the cross dichroic prism 27.
, 35 (see FIG. 2) and a convex portion 42 provided on each of the transmissive liquid crystal panels 41R, 41G, and 41B. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

The convex portion 42 is an emission surface that emits modulated R light in the transmissive liquid crystal panel 41R for R light, an emission surface that emits modulated G light in the transmissive liquid crystal panel 41G for G light, and for B light. Of the transmissive liquid crystal panel 41B, it is formed on the exit surface for emitting the modulated B light. Convex part 42
Is a convex curved surface having a curvature in a two-dimensional direction, and has a condensing function for condensing light. The convex surface part 42 functions as a light collecting means.

FIG. 5 schematically shows a cross-sectional configuration of the transmissive liquid crystal panel 41R for R light. The R light transmissive liquid crystal panel 41R includes an incident side substrate 51 and an emission side substrate 58 made of a transparent member. The incident-side substrate 51 is provided on the side of the R light transmissive liquid crystal panel 41R on which the R light to be modulated is incident. The emission-side substrate 58 is provided on the side of the R-light transmissive liquid crystal panel 41R that emits the modulated R light. The liquid crystal layer 55 is sealed by the incident side substrate 51 and the emission side substrate 58. A transparent electrode 52 is provided between the incident side substrate 51 and the liquid crystal layer 55.
In addition, an alignment film 53 is provided. Between the emission side substrate 58 and the liquid crystal layer 55, the transparent electrode 5 is provided.
7 and an alignment film 56 are provided. The spacer 54 includes the incident side substrate 51 and the emission side substrate 5.
8, a uniform space for providing the liquid crystal layer 55 is ensured.

The convex surface portion 42 is formed on the surface of the emission side substrate 58 on the side from which the R light modulated by the liquid crystal layer 55 is emitted. The convex surface portion 42 includes a liquid crystal layer 55 in the transmissive liquid crystal panel 41R for R light.
Is provided at a position where the R light modulated in (1) enters. The G light transmissive liquid crystal panel 41G and the B light transmissive liquid crystal panel 41B are configured in the same manner as the R light transmissive liquid crystal panel 41R. The convex surface portion 42 may be either spherical or aspherical.

The convex surface portion 42 is formed, for example, by polishing the surface of the plate member. The transmissive liquid crystal panels 41R, 41G, and 41B are formed by combining the emission side substrate 58 on which the convex surface portion 42 has been formed in advance with other components. The projector 40 includes concave surface portions 33, 34, and 35 formed on the cross dichroic prism 27, and transmissive liquid crystal panels 41R and 41G.
, 41B and the convex surface portion 42, the condenser lens and the diverging lens can be made unnecessary, and the configuration can be made small and simple.

In the projector 40 according to the present embodiment, a diverging lens may be separately provided in place of the concave surface portions 33, 34, and 35 formed in the cross dichroic prism 27. The diverging lens is, for example, a concave lens. The concave lens functions as a diverging means having a diverging action for diverging light. The projectors 10 and 40 according to the present invention may be configured to have at least one of a convex surface portion formed on the spatial light modulation element and a concave surface portion formed on the color synthesis optical element.

The projectors 10 and 40 according to the present invention are not limited to the configuration including a spatial light modulation element for each color light. The projectors 10 and 40 may be configured to modulate two or more color lights with one spatial light modulation element. The projectors 10 and 40 are not limited to the case where an ultrahigh pressure mercury lamp is used as the light source unit 11, but a lamp other than the ultrahigh pressure mercury lamp, a solid light source such as a light emitting diode (LED) or a super luminescence diode (SLD), a laser light source, or the like. It is good also as a structure using. The projectors 10 and 40 may be so-called rear projectors that supply light to one surface of a screen and observe an image by observing light emitted from the other surface of the screen.

1 is a diagram illustrating a schematic configuration of a projector according to a first embodiment of the invention. The figure which shows the isometric view structure of a cross dichroic prism. The conceptual diagram explaining the effect | action of a condensing lens and a concave-surface part. FIG. 5 is a diagram illustrating a schematic configuration of a projector according to a second embodiment of the invention. The figure which represented typically the cross-sectional structure of the transmissive liquid crystal panel for R light.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Projector, 11 Light source part, 12 1st integrator lens, 13 2nd integrator lens, 14 Polarization conversion element, 15 Superimposition lens, 16, 18 Reflection mirror, 17 1st dichroic mirror, 19R R light field lens, 19G G light Field lens for 19B light, transmissive liquid crystal panel for 20R R light, transmissive liquid crystal panel for 20G G light, transmissive liquid crystal panel for 20B B light, condensing lens for 21R R light, for 21G G light Condensing lens, Condensing lens for B light, 22 Second dichroic mirror, 23, 25 Relay lens, 24, 26 Reflecting mirror, 27 Cross dichroic prism, 28 Projection lens, 29 Screen, 31 First dichroic film, 32 2 dichroic membrane, 33 1st concave part, 34 2nd concave Part, 35 third
Concave part, 36 exit surface, AX optical axis, 40 projector, 41R R light transmissive liquid crystal panel, 41G G light transmissive liquid crystal panel, 41BB light transmissive liquid crystal panel, 42 convex surface part, 51 incident side substrate, 52, 57 Transparent electrode, 53, 56 Alignment film, 54 Spacer,
55 Liquid crystal layer, 58 Ejection side substrate

Claims (6)

A plurality of spatial light modulators for modulating light according to an image signal;
A color synthesis optical element for synthesizing light modulated by the plurality of spatial light modulation elements;
A light condensing means provided at a position where light modulated by the spatial light modulation element is incident and having a light condensing function for condensing the light;
A diverging means provided at a position where light to be synthesized by the color synthesizing optical element is incident, and having a diverging action for diverging the light,
Formed on the exit surface of the spatial light modulator that emits the modulated light, formed on the convex surface functioning as the condensing means, and the incident surface on which the light to be combined among the color combining optical elements is incident; A projector having at least one of a concave surface portion functioning as the diverging means. The projector according to claim 1, comprising the convex surface portion formed in the spatial light modulation element and the concave surface portion formed in the color synthesis optical element. The projector according to claim 1, wherein the diverging unit collimates light incident from the condensing unit. The projector according to claim 3, wherein a rear focal point of the condensing unit and a front focal point of the diverging unit substantially coincide with each other. The spatial light modulator is a transmissive liquid crystal panel,
5. The projector according to claim 1, wherein the convex surface portion is formed on an emission-side substrate provided on a side that emits modulated light in the transmissive liquid crystal panel. . A first spatial light modulator that is the spatial light modulator that modulates the first color light;
A second spatial light modulator that is the spatial light modulator that modulates second color light;
A third spatial light modulator which is the spatial light modulator that modulates the third color light,
The color synthesizing optical element includes a first concave surface portion that is the concave surface portion formed on an incident surface on which the first color light modulated by the first spatial light modulation device is incident, and the second spatial light modulation device. A second concave surface portion which is the concave surface portion formed on the incident surface on which the modulated second color light is incident, and the third
And a third concave surface portion that is the concave surface portion formed on an incident surface on which the third color light modulated by the spatial light modulator is incident. The projector described.

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