JP2001142028A - Reflection type liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal projector in which a case in which contrast is prioritized and a case in which brightness is prioritized can be selected. SOLUTION: A slide shutter 150 is provided on a light beam emitting side near a 2nd fly-eye integrator 113 out of 1st and 2nd fly-eye integrators 107 and 113. When the contrast is prioritized, the shutter 150 is closed. In this case, it is desirable that the shape of a pupil satisfies an angular aperture PP > an angular aperture PI, wherein the angular aperture in a main incident surface direction formed by the normal of the splitter surface of a polarizing beam splitter 21 and the optical axis of a projection lens 139 is PI and the angular aperture in a direction perpendicular to the main incident surface is PP.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type liquid crystal projector provided with a fly-eye integrator and a polarizing beam splitter.

[0002]

2. Description of the Related Art Conventionally, an image displayed on a liquid crystal element is irradiated with plane polarized light, and plane polarized light in a predetermined direction is extracted from elliptically polarized light reflected by a pixel corresponding to the image on the liquid crystal element. There is known a reflection type liquid crystal projector that projects the light on a screen by a projection lens. FIG. 1 shows an example of such a reflective liquid crystal projector. The projector includes light source means (not shown)
, A polarizing beam splitter 21, a liquid crystal element 23, and a projection lens 25. In FIG. 1, the light source means (not shown) includes a lens (not shown) whose optical axis is parallel to the Y axis, and the polarization beam splitter 21 has a splitter surface (2).
The normal line n of the junction surface of the two prisms exists in the YZ plane and is arranged so as to form an angle of 45 ° with the Y axis / Z axis. The surface of the liquid crystal element 23 is Z
The projection lens 25 is arranged so as to be orthogonal to the axis, and the optical axis thereof is parallel to the Z axis.

[0003] Of the light rays R0, R1 and R2 from the light source means, a light ray (main incident light ray) R0 parallel to the Y axis is incident on the splitter surface of the polarizing beam splitter 21 at an angle of 45 °. When the incident light beam is white light, the polarization beam splitter 21 oscillates the P wave (P) oscillating in parallel with the Y-axis and the main incident surface 27 defined by the normal line n of the polarization beam splitter 21 in the energy of the incident light beam R0. (Polarized light component), and reflects an S-wave (S-polarized light component) oscillating in a direction perpendicular to the main incident surface 27, and is directed to the liquid crystal element 23 along the Z axis. The light beam reflected by the liquid crystal element 23 is again reflected along the Z axis by the polarization beam splitter 21.
Head to.

At this time, the light beam reflected from the portion where the liquid crystal element 23 acts as a mirror surface becomes S-polarized light again. Therefore, this light beam is reflected by the polarization beam splitter 21 and travels toward the light source. On the other hand, the liquid crystal element 23
The light beam reflected at a portion where a predetermined image is generated becomes elliptically polarized light due to birefringence at that portion, and is incident on the polarizing beam splitter 21. The S-wave component is reflected by the polarization beam splitter 21 and travels toward the light source. The P-wave component passes through the polarization beam splitter 21 and is projected via a projection lens 24 onto a screen (not shown). Is formed.

[0005] Light from the light source means enters the polarization beam splitter 21 as a light beam. Therefore, the light from the light source means includes not only the light R0 but also the light R1 and the light R2. The light ray R <b> 1 is input to the polarization beam splitter 21 at an angle inclined with respect to the Y axis in the main incident plane (YZ plane) 27. Since this light ray R1 is on the main incident surface 27 whose incident optical axis is defined by the lens optical axis L and the normal line n, the reflected light (S wave) reflected by the polarization beam splitter 21 is incident on the main incident surface 27. Vibrates vertically. Therefore, when this reflected light is incident on a portion of the liquid crystal element 23 that acts as a mirror surface, the reflected light is reflected as it is, has linearly polarized light in a direction orthogonal to the main incident surface 27 again, and is reflected by the polarization beam splitter 21. The light is reflected toward the light source.

On the other hand, of the light rays from the light source means,
A ray R2 incident along an incident direction inclined with respect to the main incident surface 27 (this is assumed to be, for example, in the XZ plane).
Is separated by the polarization beam splitter 21, the reflected light from the polarization beam splitter 21 becomes linearly polarized light that oscillates in a direction orthogonal to the incident surface determined by the incident direction of the light beam R2 and the normal line n. The direction of this linearly polarized light is indicated by S2 in FIG. As shown in the figure, the vibration direction S2 has an angle α clockwise shifted with respect to an axis (X axis) orthogonal to the main incident surface 27 in the traveling direction. When the S wave having the vibration direction S2 is reflected by the liquid crystal element 23 (more specifically, when it is reflected by a portion of the liquid crystal element 23 that acts as a mirror surface), the light reflected by the liquid crystal element 23 in FIG. It has a polarization direction S2 'shifted by the same angle α with respect to the X axis. The linearly polarized light in the polarization direction S2 'is input to the polarization beam splitter 21.

By the way, as described above, the polarization beam splitter 21 is arranged so that the incident direction of the light beam and the polarization beam splitter 2
It has a function of completely reflecting linearly polarized light having a vibration direction perpendicular to the incident surface defined by the normal n of 1 and completely transmitting a vibration component parallel to the incident surface. The reflected light (reflected light of the light ray R2) from the liquid crystal element 23 is transmitted to the polarization beam splitter 2
As shown in FIG. 2, the direction perpendicular to the incident surface formed by the normal n of 1 is a direction S having an angle of (−α) with respect to the X axis.
4. Therefore, of the linearly polarized light S2 'of the reflected light, S4
Are reflected by the polarizing beam splitter 21, but components in a direction orthogonal to S4 are transmitted through the polarizing beam splitter 21 and projected on a screen. As a result, for example, a portion that should be black on the screen is lightened and the contrast is reduced.

FIG. 3 shows the amount of light that leaks unintentionally from the polarizing beam splitter 21 in the reflection type liquid crystal projector shown in FIG. Here the opening angle is ± 6 °
Is set to In FIG. 3, each numeral (%) represents the amount of light leaking when the distribution of the light amount is uniform at the position where each numeral is located. That is,
A place described as 1% indicates that 1% of light leaks. According to this, the contrast is reduced to 0.01 or less even though the aperture angle is set to ± 6 °.

FIG. 4 shows a 波長 wavelength between the polarizing beam splitter 21 and the liquid crystal element 23 in which the fast axis or the slow axis is aligned with the direction of the main incident surface 27 in order to prevent a decrease in contrast. The configuration in which the plate 31 is placed is shown. In this configuration, the light reflected by the liquid crystal element 23 passes through the quarter-wave plate 31 twice. Therefore, the 波長 wavelength plate 31 is
Acting substantially as a half-wave plate. Therefore, the light beam from the incident light beam R2 is reflected by the liquid crystal element 23 (having the polarization plane S2 'when the 波長 wavelength plate does not exist, but is reflected when the 波長 wavelength plate 31 exists). ), It becomes linearly polarized light having a polarization plane S4 (FIG. 2), and when it is input to the polarization beam splitter 21, it is completely reflected by the polarization beam splitter 21 and does not transmit to the projection lens 25 side.

The details are as follows. That is, if the angle of deviation of the polarization direction from the orthogonal direction of the main incident surface 27 in the reflected light beam generated by reflecting the light beam R2 on the polarization beam splitter 21 is α (FIG. 2), the Jones vector of the reflected light beam is

(Equation 1) It is represented by Then, the Jones vector after being reflected by the liquid crystal element 23 and passing through the quarter-wave plate 31 is

(Equation 2) It is represented by

Here, the fast axis or slow axis (optical axis) of the quarter-wave plate 31 is arranged so as to be orthogonal to the main incident surface 27 (that is, arranged in parallel with the X axis). ). Therefore, the polarization direction of the light beam that has passed through the quarter-wave plate 31 is rotated by −2α from the polarization direction S2 of the incident light beam, and has a polarization direction S4. As described above, this polarization direction S4 is perpendicular to the incidence plane defined by the normal line n of the polarization beam splitter 21 and the incident direction of the reflected light beam, the rate of passing through the polarization beam splitter 21 is zero, and No light reaches the lens and high contrast is obtained.

[0012]

However, in a conventional reflection type liquid crystal projector, a polarizing beam splitter 2 is used.
Due to the characteristic 1, the P-wave (P-wave polarization component) from the quarter-wave plate 31 may still pass through the polarization beam splitter 21, thereby causing a problem that the image contrast is reduced. . In addition, there are cases where an image with a high contrast is easier to see, and cases where a bright image is easier to see even if the contrast is slightly reduced, and there has been a problem that the conventional reflection type liquid crystal projector cannot select the image.

The present invention has been made in view of such a problem, and it is possible to select between a case where priority is given to contrast and a case where priority is given to brightness. It is an object of the present invention to provide a reflection type liquid crystal projector capable of forming a bright image by capturing light emitted from a light source with high efficiency while maintaining high contrast while minimizing the contrast.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention provides first and second fly-eye integrators for condensing light rays from a light source, and the first and second fly-eye integrators.
And a reflection type liquid crystal projector provided with a polarizing beam splitter for polarizing a light beam from the second fly's eye integrator, and a normal to a splitter surface of the polarizing beam splitter and incident on the polarizing beam splitter from the second fly's eye integrator. A reflection type liquid crystal projector, comprising: a slide shutter for adjusting a width in a direction parallel to a main incident surface of the light beam formed by an optical axis of the light beam to be formed, provided near the second fly-eye integrator. Is provided.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a preferred outline of a reflection type liquid crystal projector of the present invention will be described with reference to the accompanying drawings. The above-mentioned problem that the contrast of the image is reduced is caused by, for example, changing the shape of the pupil when viewing the light source side from the liquid crystal surface.
A main incident surface 2 formed by a normal line n of the splitter surface (joining surface) of the polarization beam splitter 21 and the optical axis of the projection lens 25
When the opening angles in the seven directions are PI and the opening angle in the direction perpendicular to the main incidence surface 27 is PP, the problem can be solved by setting PP> PI. Here, the main incident surface 27 is formed by a light beam that travels along the optical axis of the optical element that emits the incident light beam and a normal line n of the polarization beam splitter 21 among the incident light beams incident on the polarization beam splitter 21. Plane. In the case of the projector of the present invention, this surface is the same as the surface formed by the normal line and the optical axis of the projection lens 25. The pupil aperture angle is the aperture angle as viewed from the position of the liquid crystal surface.

Here, in order to explain that the problem that the contrast is reduced by the above configuration is solved, the characteristics of the polarizing beam splitter which causes the problem will be described.

As shown in FIG. 5, the splitter surface of the polarizing beam splitter 21 has an incident light i with respect to its normal n.
Is designed to completely reflect the S-wave of the incident light beam and completely transmit the P-wave when the light is incident at approximately θ = 45 °.
However, if the angle of incidence deviates significantly from 45 °, its function will be reduced. For example, as shown in FIG. 5, when the luminous flux of the incident light becomes thick, the incident angle θ ± φ with respect to the normal line n of the light ray i ′ of the peripheral light in the luminous flux is 45 °.
, The amplitude of the S-wave transmitted through the polarizing beam splitter 21 and the amplitude of the P-wave reflected by the polarizing beam splitter 21 may increase. This situation will be described in more detail as follows.

FIG. 6 shows an example of the characteristics of the polarization beam splitter 21. 6, the horizontal axis represents the wavelength λ (unit: nm) of the incident light, and the vertical axis represents the transmittance T (%) of the polarizing beam splitter 21. 4 shown in FIG.
Wavelengths between 50 nm and 600 nm correspond to green light. In FIG. 6, the curve indicated by S (45 °) indicates that the incident light and the normal n of the polarization beam splitter 21 are 45 °.
Represents the transmittance of the S wave when In other words, in this case, the S-wave at 450 nm to 600 nm is completely reflected by the polarizing beam splitter 21. The curve P (45)
°), the normal line n of the polarizing beam splitter 21
The P-wave of the light beam incident at an angle of 45 ° with respect to the above is completely transmitted through the polarizing beam splitter 21.

On the other hand, as shown by a curve S (51 °), an S-wave incident on the polarizing beam splitter 21 at an incident angle of, for example, 51 ° with respect to its normal line n is completely reflected at a short wavelength. However, at a wavelength around 600 nm, part of the energy passes through the polarizing beam splitter 21. Further, as shown by the curve P (39 °), the polarization beam splitter 21
The P wave incident at an incident angle of 9 ° is 450 nm to 5 nm.
At a wavelength of 00 nm, part of the energy is reflected and the brightness is reduced.

In the above, the characteristics of the polarizing beam splitter 21 with respect to the light of the green wavelength have been described.
The same applies to the characteristics of the polarization beam splitter 21 with respect to a light beam having a blue wavelength. That is, for a light beam incident on the polarizing beam splitter 21 at an angle deviating from the normal line n by 45 °, the P wave and the S wave are not completely separated as desired.

Therefore, the incident light and the polarization beam splitter 2
If the angle formed by the normal n of 1 is significantly shifted from 45 ° (eg, ± 6 °), the 波長 wavelength plate 31 described with reference to FIG.
However, light leaks from the polarizing beam splitter 21, resulting in a decrease in contrast and a decrease in brightness.

FIGS. 7 and 8 show that the angle between the incident light and the normal n of the polarization beam splitter 21 is approximately 45 ° (for example, the difference from 45 ° is within ± 6 °), and the polarization beam splitter 21 Represents the incident range of incident light in which no light leaks from Here, FIG. 7 shows a Poincare sphere, and the polarizing beam splitter is denoted by reference numeral 21. As described with reference to FIG. 6, among the light beams input to the polarization beam splitter 21, for a light beam having a center angle of 45 ° with respect to the normal line n, for example, a light beam of ± 6 ° before and after the light beam, The beam splitter 21 functions normally, and the linearly polarized light in the S direction and the linearly polarized light in the P direction are correctly separated. A hatched portion (ring-shaped portion) 41 in FIG. 7 indicates a range in which such a ray exists (that is, a range in which the angle of the incident ray with respect to the normal n is, for example, 39 ° to 51 °). In the light beam incident from the oblique line portion 41, the linearly polarized light in the S direction and the linearly polarized light in the P direction are correctly separated by the polarizing beam splitter 21, and the linearly polarized light in the S direction is completely reflected by the polarizing beam splitter 21, and the linearly polarized light in the P direction Completely pass through the polarizing beam splitter 21.

FIG. 8 shows the shape of the hatched portion (ring-shaped portion) 41 when viewed from the liquid crystal element 23 side. FIG.
In FIG. 7, what is indicated by reference numeral 41 is the projection of the hatched portion 41 in FIG. 7 onto the XY plane. In the reflection type liquid crystal projector using the polarization beam splitter 21, when viewed from the liquid crystal element 23, the light beam passing through the circular tube portion 41 correctly corrects the S-wave linear polarization and P light by the polarization beam splitter 21.
Although the wave linear polarization is separated, the light passing outside this region does not correctly separate the S wave linear polarization and the P wave linear polarization.
That is, there is a component that transmits through the polarization beam splitter 21 even in the S wave, and a component that is reflected by the polarization beam splitter 21 also in the P wave.

Further, in the projector of the present invention in which the polarization beam splitter 21 and the reflection type liquid crystal element 23 are combined, when the reflected light enters the polarization beam splitter 21 after the light is reflected by the liquid crystal element 23, the angle of incidence is Is reversed. In FIG. 9, the reference numeral 42 indicates that when the reflected light from the liquid crystal element 23 enters the polarization beam splitter 21,
This shows the range of the reflected light beam whose incident angle with respect to the normal line n is, for example, 39 ° to 51 °.

Therefore, finally, the polarization beam splitter 2
In order for the S-wave linearly polarized light and the P-wave linearly polarized light to be properly separated by 1, the light beam needs to pass through an elongated area (elongated area) 43 where the area 41 and the area 42 in FIG. 9 intersect. In other words, the light passing outside the elongated range 43 does not correctly separate the S-polarized light and the P-polarized light, resulting in deterioration of the contrast. The length b in the X-axis direction of the elongated range 43
Has a length that is at least five times the length a in the Y-axis direction.

In view of the above, the present invention is configured such that a pupil having a shape corresponding to the elongated range 43 is formed. That is,
The shape of the pupil when the light source side is viewed from the liquid crystal surface of the liquid crystal element 23 is defined by the direction of the main incident surface 27 formed by the normal line n of the splitter surface (joining surface) of the polarizing beam splitter 21 and the optical axis of the projection lens 25. Is defined as PI, and when the opening angle in the direction perpendicular to the main incidence surface 27 is defined as PP, PP> PI.
Thereby, light rays passing outside the elongated area 43 are blocked, and a high-contrast image can be realized.
Further, the light passing through the elongated range 43 is used efficiently, and a bright projector can be realized. Further, the opening angle PP is preferably larger than 1.2 times the opening angle PI. Thereby, an extremely bright projector can be realized.

As described above, the long width b of the narrow area 43 is at least five times the short width a. Therefore, an extremely bright projector can be realized by using a pupil having a ratio of the opening angle PP to the opening angle PI proportional to this range.

Further, as shown in FIG. 10, when the polarizing beam splitter 21 is made of a glass prism 44, incident light is refracted at the entrance / exit surface (joining surface) of the glass prism 44. Therefore, in this case, as shown in FIG. 11, an elongated area 45 that is further elongated in the X-axis direction is formed. The region in FIG. 11 shows the case where the refractive index of the prism is 1.8 in more detail. In this case, the optical axis (Y of the main incident ray with respect to the normal n of the polarization beam splitter 21)
Axis) is 45 °, and as shown in FIG. 10, the allowable deviation angle φ is 3.32 °.

The vertical opening angle PP is preferably smaller than 60 °. This facilitates lens aberration correction. An opening angle of 60 ° corresponds to 1 in the F-number. Therefore, it is generally difficult to realize a projection lens 25 having a brightness exceeding this angle.

Another aspect of the present invention is a reflection type liquid crystal projector including a polarizing beam splitter 21, a quarter-wave plate 31, and a projection lens 25, as viewed from the light source side from the front (screen side) of the projection lens 25. The shape of the pupil when
A main incident surface 2 formed by a normal line n of the splitter surface (joining surface) of the polarization beam splitter 21 and the optical axis of the projection lens 25
When the opening angle in the seven directions is PI and the opening angle in the direction perpendicular to the main incident surface 27 is PP, PP> PI. The opening angle PP is preferably larger than 1.2 times the opening angle PI.

The pupil preferably has an image formed by a lens system of the stop when the stop placed between the polarizing beam splitter 21 and the light source is viewed from the liquid crystal surface of the liquid crystal element 23 or the screen side of the projection lens 25. It is. This diaphragm is preferably a fly-eye integrator (a second fly-eye integrator in an embodiment described later).

Another aspect of the present invention relates to a reflection type liquid crystal projector having a polarizing beam splitter 21, a quarter-wave plate 31, and a projection lens 25, the shape of a diaphragm means having a function of determining a light beam passing through an optical system. Is compared with the width in the direction perpendicular to the main incidence surface 27 formed by the normal line n of the splitter surface (joining surface) of the polarizing beam splitter 21 and the optical axis of the projection lens 25, Is large. It is desirable that the width in the direction perpendicular to the main incident surface 27 is larger than 1.2 times the width in the direction parallel to the main incidence surface 27.

The function of the aperture means is fulfilled, for example, by a fly-eye integrator arranged between the light source and the polarizing beam splitter 21. In this case, the shape of the stop is the outer shape of the fly-eye integrator.

An embodiment of the reflection type liquid crystal projector of the present invention will be described below with reference to FIGS.

In the embodiment shown in FIG. 12, a lamp 101 is provided as a light source. The light beam emitted from the lamp 101 is reflected by the reflector 103, then focused by the condenser lens 105, and made incident on the first fly-eye integrator 107. Here, the light rays reflected by the reflector 103 and focused by the condenser lens 105 are distributed rotationally symmetrically with respect to the reflector axis 109. Therefore, the first fly-eye integrator 107 is formed into a nearly circular outer shape as shown in FIG.

As shown in FIG. 13, the first fly's eye integrator 107 is composed of a number of lens elements 111. Then, a spot image of the light source by each lens element 111 of the first fly-eye integrator 107 is formed on a corresponding lens element 115 of the second fly-eye integrator 113 (FIG. 14).

The light rays from the second fly-eye integrator 113 are split by the dichroic mirrors 117 and 119 into light rays of, for example, red, blue and green wavelengths. Each of the split light beams is transmitted to a field lens 121, 123, 12.
5 (and, depending on the case, the relay lens 127, the reflection mirror 128, and the relay lens 129), the image forming apparatuses 131, 133 for forming images for the respective wavelengths.
135. Here, the image forming apparatuses 131 and 13
3, 135 has a configuration similar to that shown in FIG. 4, for example, and includes a polarizing beam splitter 21, a quarter-wave plate 31, and a liquid crystal element 23, respectively. Image forming apparatus 13
Light beams having respective wavelengths from 1, 133 and 135 are combined by a color combining prism 137, and projected onto a screen (not shown) via a projection lens 139 similar to the projection lens 25.

FIG. 15 is an image which can be seen in the projection lens 139 when the projection lens 139 is viewed from the screen side (the left side in FIG. 12), and the second fly eye is provided in the pupil 139a of the projection lens 139. Integrator 11
The third image 113 'can be seen. Therefore, in this reflection type liquid crystal projector, the second fly-eye integrator 113 substantially functions as an aperture stop. That is, the spot image from the first fly-eye integrator 107 is
The light may protrude from the element of the second fly-eye integrator 113 due to the spread of the light, but the protruded light is kicked by the liquid crystal element 23 or the projection lens 139 and substantially passes through the optical system of the reflection type liquid crystal projector. Can not. Therefore, in the optical system of this projector, the image formed by the lens system having the outer shape of the second fly-eye integrator 113 becomes the pupil shape of the entire optical system.

By the way, as already described with reference to FIGS. 7 to 9, due to the characteristics of the polarizing beam splitter 21, the normal line n of the polarizing beam splitter 21 and the projection lens 1
A region 4 elongated in a direction (X-axis direction in FIG. 12) perpendicular to the main incident surface 27 formed by the 39 (or 25) optical axis.
3, the P-polarized light component and the S-polarized light component are correctly separated by the polarizing beam splitter 21.
In a light ray passing outside the elongated area 43, the P-polarized light component and the S-polarized light component are not correctly separated, and the contrast is reduced.

Accordingly, the width 113a of the second fly-eye integrator 113 in the direction (Y-axis direction in FIG. 12) parallel to the normal line n of the polarizing beam splitter 21 and the optical axis of the projection lens 139 (Y-axis direction in FIG. 12). (FIG. 14)
Is designed to be relatively short so that the light beam that has passed through the second fly-eye integrator 113 and reached the polarization beam splitter 21 falls within the width a of the elongated range 43 in the Y-axis direction. Thereby, a high-contrast image can be formed on the screen. That is, if the width 113a in the Y-axis direction is increased, the ratio of wasted light rays can be reduced, but using light rays that pass outside the width 113a causes a decrease in image contrast on the screen.

On the other hand, the normal line n of the polarization beam splitter 21
And the width 113b (FIG. 14) of the second fly-eye integrator 113 in a direction perpendicular to the main incident surface 27 formed by the optical axis of the projection lens 139 (the X-axis direction in FIG. 12).
Is designed to be relatively long, and is set such that the light beam that has passed through the second fly-eye integrator 113 and has reached the polarization beam splitter 21 falls within the width b of the elongated range 43 in the X-axis direction. By setting the width 113b in the X-axis direction to be larger than the width 113a in the Y-axis direction, light emitted from the lamp 101 can be efficiently transmitted to the liquid crystal element 23.
To illuminate the screen with good contrast.

In short, by shortening the width 113a in the X-axis direction and increasing the width 113b in the Y-axis direction, the proportion of the light that is protruded and wasted is reduced, and the light emitted from the lamp 101 can be efficiently transmitted to the liquid crystal element. 23 to illuminate the screen with good contrast. Note that X
It is needless to say that the shape of the other elements of the optical system needs to be increased in the corresponding direction in accordance with the increase in the axial width 113b.

As described above, in the reflection type liquid crystal projector using the polarization beam splitter 21 and the quarter-wave plate 31 in combination, the shape of the pupil is made horizontally long (for example, the aperture in the direction parallel to the main entrance surface 27). By increasing the opening angle PP in a direction perpendicular to the main incident surface 27 with respect to the angle PI), a bright projector can be realized without lowering the contrast. In other words, by extending the pupil shapes of the light source system and the projection system in a direction perpendicular to the main entrance surface 27 instead of a circle, more light from the light source can be taken in at a wide aperture angle, thereby realizing a bright projector. it can.

The rate of extension in the vertical direction is preferably such that the opening angle PP in the direction perpendicular to the main incident surface 27 is larger than 1.2 times the opening angle PI in the direction parallel to the main incident surface 27. Otherwise, the effect of spreading in the vertical direction is small, and improvement in luminance cannot be expected. The outer shape of each lens constituting the projection lens 139 is generally circular, and the opening angle P in the vertical direction is
If P is much larger than the opening angle PI in the parallel direction, a useless lens area that does not contribute to the formation of a projected image increases.

With the above arrangement, it is possible to increase the contrast while securing a bright projected image (minimizing the decrease in brightness). The present invention is configured as follows so that a case where priority is given to contrast and a case where priority is given to brightness can be selected. As shown in FIG. 12, a slide shutter 150 is provided on the light emitting side of the second fly-eye integrator 113. The slide shutter 150 is slidable in the Y direction, and can adjust the width of the second fly-eye integrator 113 in the Y direction.

FIG. 16 shows the second fly-eye integrator 113 when the slide shutter 150 is provided. Second fly-eye integrator 11 shown in FIG.
In 3, the width 113a in the Y-axis direction is shortened in advance, and X
Although a fly-eye integrator having a shape in which the width 113b in the axial direction is elongated is used, when a slide shutter 150 is provided, as shown in FIG. 16, a fly-eye integrator having the same shape as the first fly-eye integrator 107 shown in FIG. The width 113a in the Y-axis direction is adjusted by the slide shutter 150 using an eye integrator.

As shown in FIG.
50 is moved to the position shown by the broken line, and the width 113 in the Y-axis direction is
If a is narrowed, it becomes the same as the second fly-eye integrator 113 shown in FIG. 14, and the contrast is prioritized. If the slide shutter 150 is moved to the position shown by the solid line and the width 113a in the Y-axis direction is increased, the brightness has priority over the contrast. The slide shutter 1
50 may be configured such that fine adjustment is performed in multiple steps or continuously at intervals smaller than the width of the lens element 115 in the Y direction.
5 may be closed. The second fly-eye integrator 11 is moved by the slide shutter 150.
The extent to which the width in the Y direction of 3 is closed may be appropriately set.

Although the slide shutter 150 operates as an aperture, it is not a circular aperture commonly used, but in only one direction, here the Y direction, that is, the normal line n of the splitter surface of the polarization beam splitter 21. From the second fly-eye integrator 113 to the polarization beam splitter 21
It is significant to narrow the light beam only in width in a direction parallel to the main incident surface 27 formed by the optical axis of the light beam incident on the light source. In a reflection type projector such as the present invention, by providing an aperture in only one direction, it is possible to select between a case where priority is given to contrast and a case where priority is given to brightness.

In this embodiment, as shown in FIG.
Although the slide shutter 150 is provided on the light-emitting side of the fly-eye integrator 113, the slide shutter 15 is provided on the light-incident side of the second fly-eye integrator 113.
0 may be provided. In any case, it is preferable to provide the slide shutter 150 in the vicinity of the second fly-eye integrator 113 on the incident side or the exit side of the second fly-eye integrator 113. Although it is conceivable to provide the slide shutter 150 on the incident side of the projection lens 139, the vicinity of the second fly-eye integrator 113 is more preferable.

[0050]

As described in detail above, the reflection type liquid crystal projector of the present invention can be used for the normal of the splitter surface of the polarizing beam splitter and the light of the light beam incident on the polarizing beam splitter from the second fly-eye integrator. A slide shutter that adjusts the width in the direction parallel to the main incident surface of the light beam formed by the axis is provided near the second fly-eye integrator, so that there are cases where contrast is prioritized and brightness is prioritized. You can choose. Even when the contrast is prioritized by closing the slide shutter, the pupil shape is such that the relationship between the opening angle PI in the direction parallel to the main incident surface and the opening angle PP in the direction perpendicular to the main incident surface is PP> PI. By setting, the decrease in brightness can be suppressed to a minimum, so that light emitted from the light source can be captured with high efficiency while maintaining high contrast, and a bright image can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a conventional reflective liquid crystal projector.

FIG. 2 is a schematic diagram showing polarization directions of incident light and reflected light to a liquid crystal element provided in the reflection type liquid crystal projector shown in FIG.

FIG. 3 is a schematic diagram showing an amount of light leakage on a screen in the reflection type liquid crystal projector shown in FIG.

FIG. 4 is a schematic diagram showing a configuration of another conventional reflective liquid crystal projector.

FIG. 5 is an explanatory diagram for illustrating an operation of the present invention, and is a diagram illustrating an incident angle of an incident light beam on a polarizing beam splitter.

FIG. 6 is an explanatory view showing the operation of the present invention, and FIG.
FIG. 7 is a characteristic diagram showing a change in transmittance of S-waves and P-waves according to an incident angle of a light beam.

FIG. 7 shows an incident light beam (with respect to a polarizing beam splitter) in a range where the transmittance of the S-wave and the P-wave has a desired value.
It is a schematic diagram showing an incident angle range.

8 is a schematic diagram showing a range in which the incident angle range in FIG. 7 is projected on an XY plane.

FIG. 9 is a schematic diagram showing a range of FIG. 8 and a usable range of light rays reflected on a liquid crystal element surface.

FIG. 10 is a schematic diagram showing an incident path of a light beam when the polarizing beam splitter is made of a glass prism.

FIG. 11 is a schematic diagram showing the shape of a pupil of the present invention when the polarizing beam splitter is made of a glass prism.

FIG. 12 is a schematic diagram showing an embodiment of the present invention.

FIG. 13 is a front view of the first fly's eye integrator as viewed along the line XIII-XIII in FIG. 12;

14 is a second view taken along the line XIV-XIV in FIG.
It is a front view of a fly-eye integrator.

FIG. 15 is a schematic diagram of an image in a projection lens viewed along line XV-XV in FIG. 12;

FIG. 16 is a front view of a second fly-eye integrator provided with a slide shutter according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 21 polarization beam splitter 23 liquid crystal element 25, 139 projection lens 31 quarter-wave plate 107 first fly-eye integrator 113 second fly-eye integrator 150 slide shutter

Claims (2)

[Claims] 1. A reflection type liquid crystal projector comprising: first and second fly-eye integrators for condensing light rays from a light source; and a polarizing beam splitter for polarizing light rays from the first and second fly-eye integrators. A width is adjusted in a direction parallel to a main incidence plane of the light beam, which is formed by a normal line of a splitter surface of the polarization beam splitter and an optical axis of a light beam incident on the polarization beam splitter from the second fly-eye integrator. A reflective liquid crystal projector, wherein a slide shutter is provided near the second fly-eye integrator. 2. The pupil in which, when the slide shutter is closed, a relationship between an opening angle PI in a direction parallel to the main incident surface and an opening angle PP in a direction perpendicular to the main incident surface is PP> PI. 2. The reflection type liquid crystal projector according to claim 1, wherein the shape is set.