JP3496643B2 - projector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source, a color separation optical system for separating a light beam emitted from the light source into a plurality of color lights, and each color light separated by the color separation optical system from different directions. The present invention relates to a single-plate type projector that includes an electro-optical device that is incident and that modulates each color light according to image information to form an optical image.

[0002]

2. Description of the Related Art Conventionally, a light source, a color separation optical system that separates a light beam emitted from this light source into a plurality of color lights, and the respective color lights separated by this color separation optical system are made to enter from different directions, and There is known a single-plate type projector including an electro-optical device that forms an optical image by modulating each light according to image information. According to such a projector, the electro-optical device 1 that modulates a light flux based on image information
Since it is possible to form a color projection image with one, there is an advantage that the projector can be easily downsized and can be manufactured at a lower cost than a three-plate type projector.

In such a single-plate type projector, when a light beam emitted from a light source is separated into a plurality of color lights such as RGB by a color separation optical system, three dichroic lights that reflect the red, green and blue color lights are used. The mirrors are arranged so that the light beams emitted from the light source enter at different angles. Since the incident angle of each color light on the dichroic mirror is different,
The respective color lights reflected by the respective dichroic mirrors enter the electro-optical device from different directions. In the electro-optical device, a pixel is set according to color lights incident from different directions, modulation is performed according to each color light, and a color projection image is displayed on a screen via a projection lens.

Here, in the above-mentioned electro-optical device,
The pixel area in which R, G, and B are combined is set to a substantially square shape, and the sub-pixel that modulates each color light is configured by dividing the substantially square pixel area along the incident direction of each color light. Each of the sub-pixels has a substantially rectangular shape whose short side is in the color separation direction of the color separation optical system.

[0005]

However, in the single-plate type projector having such a structure, since the sub-pixels for each color light are set in a rectangular shape, the parallel direction of each color light is set in the short side direction of the rectangular shape. When the degree is lost, there is a problem in that the light is leaked to the sub-pixels of other colored light, and color mixture or the like occurs in the image projected on the screen. In particular, if a polarization conversion optical system is provided in front of the color separation optical system in order to use the light flux emitted from the light source more efficiently, the parallelism of the emitted light flux is likely to be lost due to the polarization conversion. Is a major problem.

An object of the present invention is to provide a single-plate type projector in which color mixture does not occur in a projected image.

[0007]

In order to achieve the above-mentioned object, a projector according to the present invention comprises a light source, a color separation optical system for separating a light beam emitted from the light source into a plurality of color lights, and this color separation. A single-plate type projector comprising: an electro-optical device that forms an optical image by causing each color light separated by an optical system to enter from different directions and modulating each color light according to image information. A polarization conversion optical system is provided in front of the color separation optical system, and this polarization conversion optical system transmits one of the two types of polarized light beams,
A polarization separation film that reflects the other polarized light beam, a reflection film that reflects the polarized light beam reflected by the polarization separation film in substantially the same direction as the one polarized light beam, and the polarization directions of the two types of polarized light beams. The color separation optical system includes a plurality of mirrors, and the direction in which the other polarized light beam is reflected by the polarization separation film is such that the central axis of the light beam incident on the mirror and the mirror A columnar light guide, which is substantially orthogonal to the plane defined by the central axis of the light flux reflected by, and which divides the light from the light source into a plurality of partial light fluxes, is provided in the preceding stage of the polarization conversion optical system. A first imaging optical system in which a uniform illumination optical system including the light guide end and the polarization conversion optical system are in a conjugate relationship, and a light exit end surface in the light guide is in a conjugate relationship. A second imaging optical system is formed If, conjugate ratio in the second imaging optical system is characterized in that it is 4 or more.

According to the present invention described above, the direction in which the other polarized light beam is reflected by the polarization separation film is defined by the central axis of the light beam incident on the mirror and the central axis of the light beam reflected by the mirror. Since it is substantially perpendicular to the plane, the outgoing light flux passing through the polarization conversion optical system diffuses in the direction orthogonal to the color separation direction of the plurality of color lights. Since this emitted light flux spreads in the long side direction of the rectangular sub-pixels of each color light in the electro-optical device, the leakage of other adjacent color light to the sub-pixels is reduced, and color mixture occurs in the projected image. Can be prevented.

[0009]

In addition, 2 on the light emitting end face of the light guide body
The angle distribution of the next light source image is a side surface shape of the light guide body, for example, when the pair of side surfaces of the light guide body have tapered side surfaces that spread toward the light source side, the shape of the tapered side surface, It is determined by the F value of the light source, the angle distribution unique to the light source, and the like. Then, in general, the larger the conjugate ratio, the more the parallelism of the light imaged on the electro-optical device can be secured. The parallelism of the light varies depending on the sub-pixel pitch of each color light on the electro-optical device, but it is preferable to set the conjugate ratio to 4 or more for a pixel having a fine pitch of about 10 μm, and set the conjugate ratio to 4 or more. By doing so, it is possible to secure the parallelism of each color light and prevent the adjacent color light from leaking to the pixel, and it is possible to more reliably prevent the color mixture in the projected image.

Further, when the second image forming optical system is configured to include a superimposing lens arranged in the latter stage of the polarization conversion optical system and a collimating lens arranged in the former stage of the electro-optical device,
This color separation optical system is preferably arranged between the superimposing lens and the collimating lens.

That is, by setting the conjugate ratio in the second image-forming optical system to 4 or more, as described above, the parallelism of each color light incident on the electro-optical device can be ensured. Some distance is formed between them.
Therefore, by arranging the color separation optical system including a plurality of mirrors at such a position, it is possible to bend the light flux even in a narrow space to secure a necessary conjugate ratio and to affect other optical systems. Instead, the color separation optical system can be arranged to reduce the size of the projector.

Further, in the above-mentioned light guide, the dimension in the direction orthogonal to the plane defined by the central axis of the light beam incident on the mirror and the central axis of the light beam reflected by the mirror is It is preferable to provide tapered side surfaces that gradually widen from the light emitting end surface of the body toward the light incident end surface.

That is, when a light beam incident from the light incident end surface of the light guide is internally reflected by such a tapered side surface,
Each time the internal reflection is repeated, the angle of incidence and reflection of the light beam on the tapered side surface becomes smaller. Therefore, the tapered side surface is such that the dimension in the direction orthogonal to the plane defined by the central axis of the incident / reflected light flux to / from the mirror that constitutes the color separation optical system is gradually widened from the light emitting end surface to the light incident end surface. For example, since the distance between the tertiary light source images emitted from the light emitting end face is widened, the number of light beams that can be used after polarization conversion is increased, and the efficiency of polarization conversion by the polarization conversion optical system is improved.

Further, between the light source and the light guide body described above,
It is preferable to provide a reflection mirror that reflects the light flux emitted from the light source and supplies the light flux to the light incident end surface of the light guide. Here, it is preferable that the incident direction of the light beam incident on the reflection mirror is set substantially parallel to the emission direction of the light beam from the plurality of mirrors forming the color separation optical system.

That is, when the light flux emitted from the light source is supplied to the light incident end surface of the light guide, the light source such as a lamp is condensed on the light incident end surface of the light guide by a reflector, a lens or the like. Therefore, by disposing the reflection mirror in the middle of condensing the light flux emitted from the light source in this way, the reflection mirror can be downsized, and the projector can be downsized. Further, by setting the incident direction of the light beam incident on the reflection mirror substantially parallel to the emission direction of the light beam from the plurality of mirrors forming the color separation optical system, the optical path of the emitted light beam from the light source to the projection optical system is set. Since it can be formed in a U shape, it is more advantageous for downsizing the projector.

The above-mentioned other polarized light beam is an S-polarized light beam with respect to the polarization separation film, and this S-polarized light beam is preferably converted into a P-polarized light beam by the wave plate.

That is, the S-polarized light beam is converted into the P-polarized light beam by the polarization conversion optical system, so that the S-polarized light beam is transmitted to the mirrors constituting the color separation optical system arranged in the subsequent stage of the polarization conversion optical system. As a result, the luminous flux is incident, and the reflection efficiency of the mirror is improved. Therefore, it is possible to provide a projector with high utilization efficiency of the light emitted from the light source system.

Further, the above-mentioned polarization conversion optical system has a plurality of polarization separation films, and the plurality of polarization separation films are arranged so that their reflection surfaces are parallel to each other, or depending on the diffusion state of the incident light beam. It may be arranged.

That is, in the case of the polarization conversion optical system in which the polarization separation films are arranged so that the reflection surfaces are parallel to each other, the structure is simplified, so that the manufacture of the polarization conversion optical system is facilitated. Further, if the reflecting surface is arranged according to the diffusion state of the incident light flux, it is possible to efficiently perform the polarization separation conversion according to the diffused light emitted from the light emitting end surface of the light guide body. Separation characteristics are improved.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the projector 1 according to the embodiment of the present invention includes a light source system 10 and a uniform illumination optical system 2.
0, a color separation optical system 30, a light modulation system 40, and a projection optical system 50. In the optical path from the uniform illumination optical system 20 to the light modulation system 40, a polarization conversion array 60 serving as a polarization conversion optical system, and condenser lenses 71, 72,
81 and 82 are arranged. Then, the light flux emitted from the light source system 10 is configured to display a projection image on the screen surface via the uniform illumination optical system 20, the color separation optical system 30, the light modulation system 40, and the projection optical system 50. However, the optical path of the emitted light flux is set to a plane U-shape by the folding mirror 21 which becomes a reflection mirror which will be described later and the dichroic mirrors 31R, 31G and 31B which configure the color separation optical system 30. In the following description, three axes orthogonal to each other are X, Y, and Z, and the traveling direction of light is Z.
The axis and the direction perpendicular to the paper surface of FIG. 1 will be described by defining the Y-axis direction.

The light source system 10 includes a lamp 11 serving as a light source.
A reflector 12 having a parabolic reflection surface, and a condenser lens 13. The lamp 11 is composed of a metal halide lamp, a high-pressure mercury lamp, or the like, and is arranged in the vicinity of the focal point of the reflector 12. The light flux emitted from this lamp 11 is made uniform in the emitting direction by the reflector 12 and is collimated. The light is collected by the optical lens 13 and emitted.

The uniform illumination optical system 20 comprises a folding mirror 21 and a rod 22 which is a columnar light guide. The folding mirror 21 is arranged in the vicinity of the light incident end face of the rod 22, and the light flux emitted from the light source system 10 is reflected by the folding mirror 21 and bent 90 °, and is guided to the light incident end face of the rod 22. The light flux condensed by the condenser lens 13 forms an image on the light incident end face of the rod 22, and the primary light source image G1 is formed on the light incident end face.
(Described later) is formed. Here, the folding mirror 21 is
Since it is placed in the middle of light collection by the condenser lens 13,
A mirror surface having an area smaller than the area of the exit surface of the light flux by the lamp 11 and the reflector 12 is adopted. The reflector 12 may be an elliptical reflector. In that case, if the lamp 11 is arranged in the vicinity of the first focal point, an image is formed in the vicinity of the second focal point.
Can be omitted.

The rod 22 is, as shown in FIG.
It is an optical element that internally reflects the light that has entered the light incident end surface and emits the light substantially overlapping at the position of the light exit end surface, and is composed of a solid rod made of glass. The light emitted from the lamp 11 is condensed by the reflector 12 which is a condensing unit and the condensing lens 13, and forms the primary light source image G1 on the light incident end face of the rod 22. The light incident on the rod 22 is separated into a plurality of partial light beams according to the difference in the reflection position on the reflection surface and the number of reflections, and as shown in FIG. 4, a plurality of tertiary light source images G31, G32, G33 are arranged at predetermined positions. To form. The tertiary light source image G31 is an image of a light component emitted without being reflected by the inner surface of the rod 22. Third light source image G32
Is an image of a light component which is emitted once after being reflected once on the inner surface of the rod 22. The tertiary light source image G33 is an image of a light component that is reflected and emitted twice by the inner surface of the rod 22. on the other hand,
When the rod 22 is viewed from the light emitting end face side of the rod 22, the virtual image G2 is displayed in the XY plane including the light incident end face of the rod 22.
1, G22 and G23 can be observed. The virtual image G21 is a virtual image of a light component emitted without reflection on the inner surface of the rod 22,
The virtual image G22 is a virtual image of a light component that is reflected and emitted once on the inner surface of the rod 22, and the virtual image G23 is a virtual image of a light component that is reflected and emitted twice on the inner surface of the rod 22.

As shown in FIG. 2B, the cross-sectional shape of the rod 22 is such that the lateral dimension along the X-axis direction is the dimension a for both the light incident end face 22A and the light emitting end face 22B, but along the Y-axis direction. The vertical dimension is set to the dimension b on the light emitting end surface 22B, whereas it is set to the dimension c larger than the dimension b on the light incident end surface 22A. That is, although the pair of side faces along the YZ plane are parallel to each other, as shown in FIG. 3, the pair of side faces corresponding to the ZX plane are the light emitting end faces 2.
The pair of tapered side surfaces are separated from each other from 2B toward the light incident end surface 22A.

Further, the ratio of a to b on the light emitting end face 22B is substantially equal to the ratio of the shape of the display area of the liquid crystal panel 42 (described later) which is the illuminated surface, and they are similar. The length of the rod 22 is the virtual image G21, which is a virtual secondary light source image.
The central rays of the light beams from G22, G23, ... (The optical axis shown by the alternate long and short dash line) are set so as to pass through the center of the light emitting end face of the rod 22. At this time, this cross-sectional shape has a spread E of the light flux that can occur when the incident light flux condensed by the condenser lens 13 on the light incident end surface of the rod 22 is in the state without the rod 22 (see FIG. 2A). If it is set to be sufficiently smaller than the above, a part of the light flux is reflected by the inner surface of the rod 22, and is divided into a plurality of partial light fluxes according to the difference between the reflection position on the reflection surface and the number of reflections.

Here, the internal reflection of the light beam incident from the light incident end face 22A of the rod 22 is different between the pair of parallel side faces and the tapered side face. That is, in the internal reflection of a pair of side surfaces that are parallel to each other, the incident / reflected angle of the light beam with respect to the side surfaces is always constant. It is emitted at the same angle as the angle. On the other hand, the internal reflection of the pair of tapered side surfaces is caused by the central axis 22 of the rod 22 as shown in FIG.
Since the tapered side surface is inclined with respect to C, the angle with respect to the central axis 22C of the rod 22 is gradually increased every time the internal reflection is repeated, that is, the incident / reflected angle with respect to the tapered side surface is increased. Therefore, the light beam incident on the light incident end face 22A at a predetermined angle is emitted at the light emitting end face at an angle larger than the incident angle.

The plurality of partial luminous fluxes separated by the rod 22 are, as shown in FIGS. 4 and 5, a condensing lens 71 and a condensing lens 7 which form a first imaging optical system 70.
Are collected by 2 and the tertiary light source images G31, G32, G33, ... Corresponding to the virtual images G21, G22, G23, ... Which are virtual secondary light source images are formed on the polarization conversion array 60.

FIG. 5 shows tertiary light source images G31, G32, G3.
It is a figure for demonstrating the condensing state of 3, ..., The state seen from the optical axis direction is shown. Tertiary light source images G31, G3
2, G33, ... The size, number, and spacing of the primary light source image G1
, The angle of incidence, the cross-sectional shape of the rod 22, the length, etc. In particular, the size of the tertiary light source image depends on the size of the primary light source image, and the distance between the light source images depends on the sectional shape and the side surface shape of the rod 22. That is, the distance between the light source images changes according to the shape of the light emitting end surface 22B of the rod 22, and if the shape of the light emitting end surface 22B is rectangular, the distance x1 between the light source images in the long side direction (dimension a direction) is It is larger than the distance y1 between the light source images in the short side direction (direction of dimension b). In addition, the distance between the light source images also changes depending on the shape of the side surface of the rod 22 that performs internal reflection, and when the pair of side surfaces corresponding to the ZX plane are tapered side surfaces as in the present embodiment,
Compared with the normal distance between the light source images on a pair of parallel side surfaces, the distance y1 in the Y-axis direction shown in FIG. 5 becomes large. Therefore, these light source images may be subjected to polarization separation and polarization conversion by using the gap of the light source images in the Y-axis direction having a relatively large gap.

As shown in FIG. 6, the color separation optical system 30 includes three sheets each having a different wavelength selection film for selectively reflecting or transmitting the red light R, the green light G and the blue light B. Dichroic mirrors 31R, 31G, 31
It has B. That is, the dichroic mirror 31
R is a mirror that reflects the red light R and transmits the green light G and the blue light B. The dichroic mirror 31G separates the green light G and the blue light B transmitted through the dichroic mirror 31R, reflects the green light G, and transmits the blue light B. Further, the dichroic mirror 31B reflects the blue light B transmitted through the dichroic mirror 31G. Since only the blue light B reaches the dichroic mirror 31B by the preceding dichroic mirrors 31R and 31G, a normal total reflection mirror may be used instead of the dichroic mirror 31B.

These three dichroic mirrors 31
R, 31G, and 31B are arranged so that the light beams emitted from the uniform illumination optical system 20 enter at different angles, and the red light R, the green light G, and the blue light reflected by the dichroic mirrors 31R, 31G, and 31B. B is branched and emitted in three directions on the XY plane (see FIG. 6). That is, all the directions in which the light flux that has passed through the uniform illumination optical system 20 is separated into the RGB color lights by the color separation optical system 30 are on the ZX plane.

The light modulation system 40, as shown in FIG.
A microlens array 41 and a liquid crystal panel 42 as an electro-optical device are provided, and a pair of polarizing plates (not shown) are arranged in front of and behind them. Micro lens array 41
Is a light flux R of each color separated by the color separation optical system 30,
G and B are used to focus light on the corresponding pixels of the liquid crystal panel 42, and each microlens 41A is arranged in a matrix.

The liquid crystal panel 42 includes a twisted nematic (T) between two transparent substrates 421 and 422 such as glass.
N) Liquid crystal 423 is enclosed. One substrate 4
A common electrode 424 and a black matrix 425 for blocking unnecessary light are formed on the substrate 21, and the other substrate 4
A pixel electrode 426, a thin film transistor (TFT) 427 as a switching element, etc. are formed on the TFT 22.
When a voltage is applied to the pixel electrode 426 via 427, the liquid crystal 423 sandwiched between the common electrode 424 and the common electrode 424 is driven. Note that a plurality of scan lines and a plurality of data lines are arranged on the other substrate 422 so that the TFTs 427 connect the gates to the scan lines, the sources to the data lines, and the drains to the pixel electrodes 426 near the intersections. Are arranged.
Then, the selection voltage is sequentially applied to the scanning lines, and the driving voltage of each pixel is written in the pixel electrode 426 via the TFT 427 of the horizontal pixel which is turned on in response to the selection voltage. TF
T427 is turned off by application of the non-selection voltage and holds the applied drive voltage in a storage capacitor or the like not shown. The pixel electrode 426 is arranged in a region corresponding to the opening of the liquid crystal panel 42 (opening of the black matrix 425), and TF
Each pixel is configured by T427 and the pixel electrode 426 (storage capacitor connected to the pixel electrode as necessary). In addition,
The liquid crystal 423 can be used not only in TN but also in various types such as a ferroelectric type, an antiferroelectric type, a horizontal alignment type and a vertical alignment type.

On the light incident side of the one substrate 421,
A microlens array 41 is provided for condensing the respective color lights R, G, B separated by the color separation optical system 30 into the corresponding sub-pixels of the liquid crystal panel 42. The microlens array 41 includes a plurality of unit microlenses 41A arranged in a matrix or a mosaic. The microlens 43 is formed on a glass plate by etching or the like, and is adhered to the substrate 421 via a resin layer (adhesive) 43 having a low refractive index. The unit microlenses 41A (lens convex portions or concave portions) of the microlens array 41 have a pitch corresponding to three times the pixel pitch of the liquid crystal panel 42 in the horizontal direction (scanning line direction). The red light R, the green light G, and the blue light B, which are emitted by reflecting the dichroic mirrors 31R, 31G, and 31B at different angles, enter the respective unit microlenses 41A of the microlens array 41 at different angles, and the respective unit microlenses are included. 41A allows the red light R, the green light G, and the blue light B to be horizontally adjacent to each other and condensed near the pixel electrodes 426 of the three pixels corresponding to the unit microlens 41A. Each unit microlens 41A of the microlens array 41
Corresponds to each color light R, G, B with this lens 41A.
The focal length is such that the incident light is condensed on the pixel electrodes of two adjacent pixels. In the figure, the green light G that is incident on the liquid crystal panel 42 in a substantially straight line is transmitted by the unit microlenses 41A of the microlens array 41 to the pixel electrode 4
It is condensed on 26G and emitted as it is. On the other hand, the green light G has an angle corresponding to the angle that the dichroic mirrors 31R and 31B have with respect to the dichroic mirror 31G.
The red light R and the blue light B which enter symmetrically with respect to each other are
Pixel electrodes 426R, 4 by unit microlens 41A
26B, respectively, and emitted at an angle symmetrical to the green light G. Incidentally, the dichroic mirror 31R,
If the order of spectroscopy in 31G and 31B is different, the incident position of the color light on the liquid crystal panel 42 shown in FIG. 7 is also different accordingly.

Such a pixel electrode 426 is shown in FIG.
, The pixel electrodes 426R, 426G, and 426B that modulate the respective color lights R, G, and B are arranged adjacent to each other along the X-axis direction, and the pixel electrodes 426R, 426G, and 42, respectively.
6B has a role as a sub-pixel, and three sub-pixels are combined to form a pixel for displaying a predetermined color. These pixel electrodes 426R, 426G, 426B
Are formed in a rectangular shape extending in the Y-axis direction, and the three pixel electrodes 426R, 426G, and 426B form a square shape. Therefore, compared with the case where a light beam whose parallelism is lost in the X-axis direction is incident, the light beam whose parallelism is lost in the Y-axis direction is less likely to cause color mixing (light leakage to adjacent sub-pixels). It is composed. In the present embodiment, the rectangular pixel electrodes 426R, 426G, 426B.
The pixel pitch in the short side direction is set to 10.5 μm, the pixel pitch in the long side direction is set to 31.5 μm, and the opening of the black matrix 425 is set to 7.5 μm in the short side direction and 17.5 μm in the long side direction. Has been done.

Each light beam condensed on the pixel electrode 426 of the liquid crystal panel 42 as described above undergoes modulation in accordance with a signal applied to the liquid crystal panel 42, and is emitted, thus forming a projection optical system. The lens unit 50 enlarges and projects it on the screen in front. The projection lens unit 50 includes a plurality of lenses arranged in a projection lens housing. A positioning unit for positioning a plurality of lenses and an adjustment mechanism for enabling focus adjustment and zoom adjustment are provided inside the projection lens housing. Since the structure of such a projection lens unit 50 is well known, its detailed description is omitted.

The polarization conversion array 60 separates the light beam emitted from the rod 22 into two polarized light beams whose polarization axes are substantially orthogonal to each other, and polarization-converts one of the polarized light beams to align the polarization axes. It has a function as an optical system.

FIG. 8 is a sectional view taken along the YZ plane, which is an embodiment of the polarization conversion array 60. Polarization conversion array 6
0 is the polarization separation film 61a, 61b, 61c, 61d, 6
1e and the reflection films 62a, 62b, 62c, 62d, 62
e and the half-wave plates 63a, 63b, 63c, 63d,
63e and light shielding plates 64a, 64b, 64c, 64d, 6
4e and a plurality of prisms 65 that form an array by filling these gaps, and are arranged in accordance with the diffusion state of the light beam incident on the polarization conversion array 60. Specifically, these are arranged so as to be symmetric with respect to the optical axis C of the light beam incident on the polarization conversion array 60 and an axis deviated in the Y-axis direction. Then, since the light flux emitted from the rod 22 described above tends to diverge with optical axis symmetry, a plurality of light fluxes may be provided so that the incident angles of the light flux on the polarization separation films 61a, 61b, 61c, 61d, 61e are the same. The prism 65 is folded back. Further, the polarization separation film 61a and the polarization separation film 61d in the substantially central portion of the polarization conversion array 60 in the Y-axis direction are arranged with a space of one pitch.

Polarization separation films 61a, 61b, 61c, 61
Reference characters d and 61e have a function as a polarization separating means for separating an incident light beam into two linearly polarized light beams whose polarization axes are substantially orthogonal to each other and emitting the light beams in different directions, and have characteristics according to the incident angle of the light beam. have. Reflective film 62a, 6
2b, 62c, 62d and 62e are the polarization separation films 61a,
S reflected by 61b, 61c, 61d, 61e
The traveling direction of the polarized light beam is determined by the polarization separation films 61a, 61b, 61
It has a function as a reflecting means for aligning the P-polarized light fluxes that have passed through c, 61d, and 62e in the traveling direction. The half-wave plates 63a, 63b, 63c, 63d, 63e have a function as a polarization axis rotating means for rotating the polarization axis of the incident S-polarized light beam to match it with the P-polarized light beam. The light blocking plates 64a, 64b, 64c, 64d, 64e are for blocking the light fluxes that enter the reflection films 62a, 62b, 62c, 62d, 62e without passing through the polarization separation films 61a, 61b, 61c, 61d, 61e. It has a function as a light shielding means. Then, each polarization separation film 61a, 61b, 61c,
61d, 61e and reflective films 62a, 62b, 62c,
62d and 61e are formed on the slope of one of the prisms 65 and are joined to the slope of the opposing prism via the film.

The polarization conversion array 60 constructed in this way
Are formed by the above-mentioned third light source images G31, G32, G33, ...
It is arranged in the optical path so as to enter c, 61d, and 61e.

Polarization separation film 61a and polarization separation film 61d
The light flux incident between the two is emitted as it is without polarization conversion. The P-polarized light flux of the light flux incident on the polarization separation film 61a arranged on the optical axis C is transmitted as the P-polarized light flux P1. On the other hand, the S-polarized light beam reflected by the polarization separation film 61a is further reflected by the reflection film 62a, is aligned in the traveling direction with the above-mentioned light beam P1, and then is transmitted through the ½ wavelength plate 63a to change its polarization plane. It is rotated by approximately 90 °, converted into a P-polarized light beam, and emitted as a P-polarized light beam P2.
Further, since the light flux incident on the polarization separation film 61b tends to be diffused, it is preliminarily bent in the prism 65 so as to be incident on the polarization separation film 61b at a predetermined angle, and then the P-polarized light is emitted in the same manner as described above. The light beams P3 and P4 are emitted. Hereinafter, the same applies to the polarization separation films 61c, 61d, and 61e. Half-wave plate 6 as polarization axis conversion means
Using 3a, 63b, 63c, 63d, 63e
This is effective in performing reliable polarization conversion with a simple method.
Although the P-polarized light flux is obtained by the polarization conversion array 60 in the present embodiment, the ½ wavelength plates 63a, 6 are used.
By arranging 3b, 63c, 63d and 63e at the exit of the polarized light beam P1, it is possible to obtain an S-polarized light beam.

The light shielding plates 64a, 64b, 64c, 64d,
64e is a light beam different from a desired polarized light beam after polarization conversion,
In the present embodiment, the entry of a light flux that becomes an S-polarized light flux after polarization conversion is reduced, and thus the polarization degree of the polarization-converted light can be improved.

Further, the respective partial light beams whose polarization directions are aligned by the polarization conversion array 60 are superimposed on the liquid crystal panel 42 described later by the condenser lens 82. Therefore,
The liquid crystal panel 42 is illuminated with one type of polarized light having a uniform illuminance distribution in the plane.

As shown in FIG. 1, the first image forming optical system 70 includes a condenser lens 71 arranged near the light emitting end face of the rod 22 and a condenser lens arranged in front of the polarization conversion array 60. 72, and these two condenser lenses 71, 72 make the light incident end face of the rod 22 and the polarization separation films 61a to 61e of the polarization conversion array 60 in a conjugate relationship.

The second image-forming optical system 80 includes condenser lenses 71 and 72 which constitute the first image-forming optical system 70, a condenser lens 81 which is arranged at the rear stage of the polarization conversion array 60, and the liquid crystal panel 42. And a condenser lens 82 arranged in the front stage of
The condenser lens 81 functions as a superimposing lens that superimposes the light flux emitted from the polarization conversion array 60, and the condenser lens 82 functions as a collimating lens that collimates the color lights R, G, and B on the liquid crystal panel 42. Have. Then, the second image forming optical system 80 makes the light emitting end surface of the rod 22 and the light incident end surface of the liquid crystal panel 42 into a conjugate relationship, and the conjugate ratio is set to 4 or more. The conjugate ratio is set to 4 or more to improve the parallelism of the emitted light flux by setting the conjugate ratio to 4 or more so that the color lights R, G, and B emitted to the pixel electrodes 426R, 426G, and 426B of the liquid crystal panel 42 are different from each other. Pixel electrodes 426R, 4
This is to prevent the color mixture from leaking to 26G and 426B, and the conjugate ratio 4 is set based on the following simulation. 1) Preconditions for simulation As conditions that influence the formation of a virtual image that is a secondary light source image, the arc length of the lamp 11, the F value on the incident side of the rod 22 (F value of the light source system 10), the length of the rod 22, The pixel pitch of the liquid crystal panel 42 is considered, and specifically, the simulation was performed by setting each value as follows. Arc length of lamp: 1 mm F value of light source: 1.3 Rod length: 60 mm (taper surface is formed on a pair of side surfaces) Pixel pitch: 10.5 μm × 31.5 μm (aperture 7.5
μm × 17.5 μm) 2) Parallelism required for incident light A degree of parallelism that does not cause color mixture by causing a light beam incident on a predetermined pixel to leak to an adjacent pixel and ensure the original transmittance of the pixel. As a necessary condition, the parallelism of incident light in the short side direction needs to be ± 3 ° or less and the parallelism of incident light in the long side direction needs to be ± 8 ° or less. 3) Relationship between Conjugate Ratio and Parallelism An image forming optical system is arranged between the light emitting end face 22B of the rod 22 and the liquid crystal panel 42, and the conjugate ratio of this image forming optical system is changed so that the pixel of the liquid crystal panel 42 can be changed. A simulation as to how much 90% of the incident light flux is within the parallelism was obtained, and the results shown in Table 1 were obtained.

[0047]

[Table 1]

In the above result, the required parallelism of 2) is almost satisfied only when the conjugate ratio is 5, but when actually observing the degree of color mixture of the transmitted light of the liquid crystal panel 42, the conjugate ratio of 4 is obtained.
However, the color mixture was judged to be an acceptable level.

From the results of the above simulation, if the conjugate ratio of the second imaging optical system 80 is set to 4 or more, the liquid crystal panel 4
It can be seen that the parallelism of the light beams incident on the second pixel electrode 426 can be ensured and the occurrence of color mixture in the projected image can be prevented.

According to this embodiment, the following effects can be obtained.

That is, the direction in which the other polarized light beam is reflected by the polarization separation films 61a, 61b, 61c, 61d and 61e of the polarization conversion array 60 is incident on the dichroic mirrors 31R, 31G and 31B of the color separation optical system 30. Central axis of light flux and dichroic mirrors 31R, 31
Since the light is substantially orthogonal to the plane (XZ plane) defined by the central axes of the light beams reflected by G and 31B, the light beam emitted through the polarization conversion array 60 is color-separated into a plurality of color lights. Diffuses in the direction orthogonal to the direction. This emitted light flux is
Since the color lights R, G, and B in the liquid crystal panel 42 spread in the long side direction of the rectangular pixel electrodes 426R, 426G, and 426B, for example, the color light G to the pixel electrode 426G is a pixel electrode 426R of another color light. 426B is less likely to leak, and color mixture can be prevented from occurring in the projected image.

Further, since the conjugate ratio of the second image forming optical system 80 is set to 4 or more, the parallelism of the color lights R, G, B incident on the liquid crystal panel 42 can be secured and the color mixture in the projected image is generated. It can be prevented more reliably.

Further, the color separation optical system 30 is provided between the condensing lens 81 which is a superimposing lens and the condensing lens 82 which is a collimating lens which constitute the second image forming optical system having the conjugate ratio of 4 or more.
Is arranged, the dichroic mirror 31R,
By bending the light flux at 31G and 31B, the light flux can be bent even in a narrow space to secure a necessary conjugate ratio, and the color separation optical system 30 can be arranged without affecting other optical systems, and the projector can be provided. 1 can be miniaturized.

The dimension of the dichroic mirrors 31R, 31G, 31B constituting the color separation optical system 30 in the direction orthogonal to the plane defined by the central axes of the incident / reflected light beams is from the light emitting end face 22B to the light incident end face 22A. Since the rod 22 having the tapered side surface that gradually widens toward the side is adopted, the interval between the tertiary light source images G31, G32, G33, ... Formed in the polarization conversion array 60 is widened, and the polarization separation film 61a, Since the luminous fluxes incident on 61b, 61c, 61d, and 61e are increased, the efficiency of polarization conversion is improved.

The folding mirror 2 serving as a reflection mirror
1, and the dichroic mirror 3 of the color separation optical system 30
Since 1R, 31G and 31B are arranged on the optical path,
The optical path from the lamp 11 to the projection optical system 50 can be U-shaped on the Z-X plane, which is more advantageous for downsizing the projector 1. In addition, the folding mirror 21
Is arranged between the condensing lens 13 and the light incident end surface 22A of the rod 22, the folding mirror 21 is arranged in the middle of condensing of the condensing lens 13, so that the folding mirror 21 can be downsized. Also in this respect, it is advantageous for downsizing the projector 1.

Further, the polarization conversion array 60 causes the S-polarized light flux (polarization separation films 61a, 61b, 61c, 61d, 61e).
) Is converted into a P-polarized light beam, so that the dichroic mirrors 31R, 31G, and 31B of the color separation optical system 30 in the subsequent stage become S-polarized light beams, and the reflection efficiency of these mirrors is increased. The projector 1 can be improved, and the utilization efficiency of the light flux emitted from the light source system 10 can be improved.

Since the reflection surfaces of the polarization separation films 61a, 61b, 61c, 61d, and 61e of the polarization conversion array 60 are arranged according to the diffusion state of the incident light beam to the polarization conversion array 60, the light of the rod 22 is emitted. Polarization separation can be efficiently performed according to the diffused light emitted from the emission end face 22B, and the polarization separation characteristic is improved.

Further, the polarization separation film 6 of the polarization conversion array 60
Since 1a and the polarization separation film 61d are arranged with a space of one pitch, and about half of the light flux incident on that portion can be used as illumination light, a polarization conversion array with little loss of light quantity can be obtained.

It should be noted that the present invention is not limited to the above-mentioned embodiment, but includes the following modifications.

In the above embodiment, the polarization separation films 61a, 61b, 61c, 61d and 61e of the polarization conversion array 60 are used.
Were arranged according to the diffusion state of the light flux emitted from the rod 22, but the arrangement is not limited to this. That is, as shown in FIG. 9, the polarization separation films 161a, 161b, 161c are arranged to be inclined in a certain direction with respect to the optical axis C, and the reflection surfaces of the polarization separation films 161a, 161b, 161c ... Are arranged parallel to each other. The half-wave plates 163a and 16
3b ..., Polarization conversion array 160 configured by adhering light-shielding plates 164a, 164b ... to the incident side may be adopted. According to such a polarization conversion array 160, the polarization separation films 161a, 161b, 161c, ... Are formed on the slopes of the prisms 165 each having a triangular side surface or a parallelogram shape.
Since the polarization conversion array 160 can be manufactured only by alternately arranging the reflective films 162a, 162b ... And alternately, the manufacture of the polarization conversion optical system can be facilitated.

Further, in the above embodiment, the polarization conversion array 60 has the S-polarized light flux (polarization separation films 61a, 61b, 61c, 61d, 61e) of the light flux emitted from the rod 22.
However, the present invention is not limited to this, and a polarization conversion optical system that converts all of them into S-polarized light beams may be adopted. Good. In this case, it suffices to dispose the half-wave plate in the portion that emits the P-polarized light flux, and it is not necessary to change the structure of the other portion of the polarization conversion array 60 of the above-described embodiment.

Further, in the above-described embodiment, the rod 22 in which the pair of side surfaces orthogonal to the Y-axis direction are tapered side surfaces is adopted, but the present invention is not limited to this, and a rectangular parallelepiped in which the incident surface and the exit surface have the same shape. -Shaped rods may be adopted.

In the above embodiment, the liquid crystal panel 42 using the TFT as a switching element is adopted as the electro-optical device, but the invention is not limited to this. That is, even the same liquid crystal panel may use the TFD as a switching element.

In each of the above embodiments, the rod 22
Although a solid glass rod was adopted, the present invention is not limited to this, and even if the present invention is applied to a projector equipped with a hollow rod composed of a cylindrical body whose inner surface is a mirror surface, The effect similar to the effect described in the form can be enjoyed.

In addition, the specific structure, shape, and the like when carrying out the present invention may be other structures and the like as long as the object of the present invention can be achieved.

[0066]

According to the present invention as described above, the direction in which the other polarized light beam is reflected by the polarization separation film is the center axis of the light beam incident on the mirror and the center axis of the light beam reflected by the mirror. Since it is substantially orthogonal to the plane defined by, the light flux emitted through the polarization conversion optical system diffuses in the direction orthogonal to the color separation direction of the plurality of color lights. Since this emitted light flux spreads in the long side direction of the rectangular sub-pixels of each color light in the electro-optical device, the leakage of other adjacent color light to the sub-pixels is reduced, and color mixture occurs in the projected image. Can be prevented.

[Brief description of drawings]

FIG. 1 is a plan view showing a structure of a projector according to an embodiment of the invention.

FIG. 2 is a schematic diagram for explaining a light beam splitting action by a rod that constitutes the uniform illumination optical system in the embodiment.

FIG. 3 is a side view of the rod in the embodiment.

FIG. 4 is a schematic diagram for explaining formation of a tertiary light source image by the rod in the embodiment.

FIG. 5 is a schematic diagram for explaining formation of a tertiary light source image by the rod in the embodiment.

FIG. 6 is a plan view showing a structure of a color separation optical system in the embodiment.

FIG. 7 is a cross-sectional view illustrating a structure of a liquid crystal panel that is the electro-optical device according to the exemplary embodiment.

FIG. 8 is a cross-sectional view showing the structure of a polarization conversion array that is the polarization conversion optical system in the embodiment.

FIG. 9 is a cross-sectional view showing a structure of a polarization conversion array which is a polarization conversion optical system which is a modification of the embodiment.

[Explanation of symbols]

11 lamp (light source) 21 folding mirror (reflection mirror) 22 rod 30 color separation optical system 31R, 31G, 31B dichroic mirror 42 liquid crystal panel (electro-optical device) 60 PBS polarization conversion array (polarization conversion optical system) 61a, 61b, 61c , 61d, 61e, 161a,
161b, 161c, 161d, 161e Polarization separation film 70 First imaging optical system 80 Second imaging optical system 81 Condensing lens (superimposing lens) 82 Condensing lens (collimating lens)

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI H04N 9/31 G02F 1/1335 530

Claims (8)

(57) [Claims] 1. A light source, a color separation optical system that separates a light beam emitted from this light source into a plurality of color lights, and the respective color lights separated by this color separation optical system are made to enter from different directions, and A single-plate type projector that includes an electro-optical device that modulates an image according to image information to form an optical image, and that includes a polarization conversion optical system that is provided before the color separation optical system. The conversion optical system transmits a polarized light beam of one of two types of polarized light beams and reflects a polarized light beam of the other, and a polarized light beam reflected by the polarized light separation film is almost the same as the one polarized light beam. The color separation optical system includes a plurality of mirrors, and the other polarization light beam is reflected by the polarization separation film. The reflection film reflects in the same direction and a wave plate that aligns the polarization directions of the two types of polarization light beams. Those who are reflected Is substantially orthogonal to a plane defined by the central axis of the light beam incident on the mirror and the central axis of the light beam reflected by the mirror, and the light source is provided in the preceding stage of the polarization conversion optical system. A uniform illumination optical system including a columnar light guide that divides the light from the light into a plurality of partial light beams, and a first imaging optical system in which the light incident end face of the light guide and the polarization conversion optical system have a conjugate relationship. A second image forming optical system having a conjugate relationship between the light emitting end surface of the light guide and the electro-optical device, and the conjugate ratio in the second image forming optical system is 4 or more. A projector to use. 2. The projector according to claim 1, wherein the second image forming optical system includes a superimposing lens arranged in a rear stage of the polarization conversion optical system and a collimating lens arranged in a front stage of the electro-optical device. A projector including a lens, wherein the color separation optical system is disposed between the superimposing lens and the collimating lens. 3. The projector according to claim 2, wherein the light guide body has a central axis of a light beam incident on the mirror,
The dimension of the light beam reflected by the mirror in a direction orthogonal to the plane defined by the central axis is gradually widened from the light emitting end face of the light guide toward the light incident end face. A projector characterized by. 4. The projector according to claim 2, wherein the light flux emitted from the light source is reflected between the light source and the light guide body, and the light is incident on the light guide body. A projector characterized in that a reflection mirror for supplying the light to the end face is provided. 5. The projector according to claim 4, wherein the incident direction of the light beam incident on the reflection mirror is set substantially parallel to the emission direction of the light beam from the plurality of mirrors forming the color separation optical system. A projector characterized by being installed. 6. The projector according to claim 1, wherein the other polarized light beam is an S-polarized light beam with respect to the polarization separation film, and the S-polarized light beam is generated by the wavelength plate. A projector which is converted into a P-polarized light beam. 7. The projector according to claim 1, wherein the polarization conversion optical system has a plurality of the polarization separation films, and the reflection surfaces of the plurality of polarization separation films are parallel to each other. A projector characterized in that it is arranged so that. 8. The projector according to claim 1, wherein the polarization conversion optical system has a plurality of the polarization separation films, and the reflection surfaces of the plurality of polarization separation films are incident light beams. A projector which is arranged according to the diffusion state of the projector.