JP2001296604A - Projection type video display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection type video display device which can reduce partial unevenness in brightness which is present in light, even when number of convex lenses of an integrator lens is few. SOLUTION: A light-scattering glass plate 1 is arranged immediately at the back of a converging lens 12. Minute reggedness is formed on the light scattering glass plate 1, and light is scattered by passing through the minute reggedness. That is, light radiated from a light source 10 and having unevenness of brightness is scattered by the light-scattering glass plate 1 just after passing through the converging lens 12 and by this dispersion, liquid crystal panels 31 (32, 33) are irradiated with light having reduced unevenness in brightness. Especially, when the number of convex lenses of lens arrays 11a, 11b is 30 or smaller, effect by the dispersion can be obtained markedly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection-type image display device which takes measures against uneven brightness of a light source.

[0002]

2. Description of the Related Art FIG. 6 is a plan view showing an example of an optical system of a conventional three-panel liquid crystal projector. The operation of this optical system will be briefly described below. The light emitted from the light source 10 passes through the integrator lens 11 and the condenser lens 12, and is guided to the first dichroic mirror 14 after the optical path is changed by 90 ° by the total reflection mirror 13. First
The red light transmitted through the dichroic mirror 14 is reflected by the total reflection mirror 15 and further guided to the liquid crystal panel 31 via the condenser lens 16. On the other hand, the light reflected by the first dichroic mirror 14 is guided to the second dichroic mirror 17. The green light reflected by the second dichroic mirror 17 is guided to the liquid crystal panel 32 via the condenser lens 18. Further, the blue light transmitted through the second dichroic mirror 17 is transmitted to the relay lenses 19 and 21,
The light is guided to the liquid crystal panel 33 through the total reflection mirrors 20 and 22 and the condenser lens 23. Each liquid crystal panel 31, 3
Modulated light (image light of each color) obtained through 2 and 33 is combined by the dichroic prism 24 to become color image light. This color image light is enlarged and projected by the projection lens 25 and projected and displayed on a screen (not shown).

FIG. 7 is a plan view showing another example of the optical system of a conventional three-panel liquid crystal projector. This optical system
The total reflection mirror 13 is arranged on the optical path between the entrance-side lens array 11a and the exit-side lens array 11b in the integrator lens 11, thereby achieving compactness.

Here, the light of the lamp 10a which is generally reflected by the reflector 10b has uneven brightness due to the uneven light emission of the lamp itself, the shadow of the lamp 10a, and the lamp insertion hole of the reflector 10b and the power supply line. . The integrator lens 11 includes a pair of lens arrays 11a and 11a.
b, and each convex lens (regardless of whether the direction of the convex lens is on the light incident side or the light emitting side) is designed to irradiate the entire surface of the liquid crystal panel, and is present in the light emitted from the light source 10. This is to average out partial luminance unevenness to reduce the light amount difference between the center and the peripheral portion of the screen. The operation of the integrator lens 11 will be described with reference to FIG. FIG.
Here, a dichroic mirror and the like are omitted for simplicity. As shown by the solid line in the drawing, the light incident on one convex lens located at the center of the incident side lens array 11a is focused near the convex lens located at the center of the exit side lens array 11b, and the condenser lens 16 ( 1
8, 23), and then the liquid crystal panel 31 (32, 3).
The entire surface of 3) is irradiated. Further, as shown by the dotted line, light incident on one convex lens located away from the center of the incident side lens array 11a is focused near the convex lens located away from the center of the exit side lens array 11b, The light is refracted in the center direction by the condenser lens 12, enters the condenser lens 16 (18, 23), and is irradiated on the entire surface of the liquid crystal panel 31 (32, 33).

[0005]

By the way, the range of incidence on the liquid crystal panel 31 (32, 33) is R1, the size of the convex lens of the integrator lens 11 is R2, and the distance between the liquid crystal panel and the exit lens array 11b. Is L1, and the distance between the entrance-side lens array 11a and the exit-side lens array 11b is L2.

R1 / L1 ≒ R2 / L2 R2 ≒ R1 × L2 / L1

As described above, the size (R2) of the convex lens of the integrator lens 11 is determined by the incident-side lens array 11a.
The longer the distance (L2) between the lens and the exit-side lens array 11b, the larger the distance. Therefore, compared to the optical system shown in FIG. 6, in the compact optical system of FIG. 7, the convex lens becomes large, and the number of convex lenses must be reduced. As described above, the integrator lens 11 is a lens in which each convex lens guides the light from the light source 10 to the entire surface of the liquid crystal panel, thereby averaging partial luminance unevenness existing in the light (cancelling each other). Therefore, if the number of convex lenses is small, sufficient averaging cannot be performed.

In view of the above circumstances, it is an object of the present invention to provide a projection type video display device capable of reducing partial luminance unevenness existing in light even when the number of convex lenses of the integrator lens is small.

[0009]

According to the present invention, there is provided a projection display apparatus, comprising: a light valve for modulating irradiated light; a light source for emitting the light;
An integrator lens configured to have an entrance-side lens array and an exit-side lens array so that each convex lens guides light from the light source to the entire surface of the light valve,
A condensing lens provided on the light exit side of the exit side lens array, wherein the light that scatters light between immediately before the exit side lens array and immediately after the condenser lens. It is characterized by having scattering means.

With the above arrangement, the light having uneven brightness emitted from the light source enters the incident side lens array,
The light is condensed by the convex lens and is dispersed by the light scattering means from immediately before entering the corresponding convex lens of the emission-side lens array to immediately after passing through the condenser lens. The bulb is irradiated with light with reduced luminance unevenness.

When the number of convex lenses in the lens array is 30 or less, the effect of the dispersion is remarkably obtained. Further, even in a configuration in which a total reflection mirror is provided on the optical path between the incident-side lens array and the output-side lens array, the effect due to the dispersion is remarkably obtained.

It is preferable that the emission-side lens array is provided with the light scattering means by being formed by a mold having minute irregularities on the inner wall surface of the cavity. According to this, since there is no need to provide a separate optical member as the light scattering means,
The number of parts can be reduced. Further, since the light scattering means is obtained at the same time as the molding, the number of steps can be reduced, the degree of light scattering can be made uniform, and the yield is improved, as compared with the case where the light scattering means is obtained by processing after molding.

[0013] The light scattering means may be provided in a part of the effective light passage area. In this case, it is preferable that the light scattering means has a shape corresponding to the uneven brightness of the light source.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal projector according to an embodiment of the present invention will be described below with reference to FIGS. Note that the same reference numerals are given to the same optical members as those shown in FIGS. 6 and 7 in the conventional section.

FIG. 1 is a plan view showing an optical system of a three-panel liquid crystal projector according to this embodiment. The white light emitted from the light source 10 including the lamp 10a such as a metal halide lamp and the reflector 10b passes through the incident side lens array 11a of the integrator lens 11, and then the optical path is changed by 90 ° by the total reflection mirror 13, so that the emission side lens array 11b, condenser lens 12, and light scattering glass plate 1
Through the first dichroic mirror 14.

The first dichroic mirror 14 transmits light in the red wavelength band and reflects light in the cyan (green + blue) wavelength band. The light in the red wavelength band transmitted through the first dichroic mirror 14 is reflected by the total reflection mirror 15, the optical path is changed, and guided to the transmission type liquid crystal panel 31 for red light through the condenser lens 16. Light is modulated by transmission. On the other hand, the first dichroic mirror 1
The light in the cyan wavelength band reflected at 4 is guided to the second dichroic mirror 17.

The second dichroic mirror 17 transmits light in the blue wavelength band and reflects light in the green wavelength band. The light in the green wavelength band reflected by the second dichroic mirror 17 is guided to the transmission type liquid crystal panel 32 for green light via the condenser lens 18 and transmitted therethrough, where the light is modulated. The light in the blue wavelength band transmitted through the second dichroic mirror 17 is guided to the transmission type liquid crystal panel 33 for blue light through relay lenses 19 and 21, total reflection mirrors 20 and 22, and a condenser lens 23. Light is modulated by transmitting the light.

The modulated light (image light of each color) obtained through the liquid crystal panels 31, 32, 33 is applied to the dichroic prism 24.
Are combined into a color image light. This color image light is enlarged and projected by the projection lens 25 and projected and displayed on a screen (not shown). Each liquid crystal panel 3
1, 32 and 33 are incident-side polarizing plates 31a, 32a and 33, respectively.
a and panel portions 31b and 32 in which liquid crystal is sealed between a pair of glass substrates (on which a pixel electrode and an alignment film are formed).
b, 33b, and the output side polarizing plates 31c, 32c, 33c.

The light-scattering glass plate 1 described above includes a condenser lens 1
2 and scatters light passing through the condenser lens 12. That is, minute irregularities are formed on the light scattering glass plate 1, and light is scattered by passing through the minute irregularities. Therefore, as shown in FIG.
The light having uneven brightness emitted from the light source 10 is dispersed by the light scattering glass plate 1 immediately after passing through the condenser lens 12, and this dispersion causes the liquid crystal panel 31 (32, 33) to be dispersed. Light with reduced luminance unevenness is emitted. In particular, the lens arrays 11a, 11
When the number of convex lenses b is 30 or less (in FIG. 1, the number of lenses is 25), the effect of the dispersion is remarkably obtained. Further, in the configuration of this embodiment in which the total reflection mirror 13 is provided between the incident-side lens array 11a and the output-side lens array 11b, the number of convex lenses must be reduced. Will be obtained.

The fine irregularities of the light scattering glass plate 1 are, for example,
It can be obtained by polishing with coarse polishing sand. Alternatively, it can be formed chemically by an etching method. The light scattering glass plate 1 is provided immediately after the condenser lens 12 (light exit side) as described above, and between the condenser lens 12 and the exit lens array 11b and immediately before the exit lens array 11b (light exit side). (Incident side). Although the light scattering glass plate 1 is shown as the light scattering means, the light scattering means is not limited to glass, but may be made of a transparent resin. Further, instead of a plate, a film shape may be used.

Further, as shown in FIG.
In the above, the light scattering portion 1a may be provided in a part of the effective light passage area (in this figure, the center of the effective light passage area). Light incident on the incidence-side lens array 11a becomes stronger toward the center, and color unevenness can often be reduced by reducing brightness unevenness only at the center. In this case, the light scattering portion 1a is adapted to correspond to the uneven light emission of the lamp itself, the shadow of the lamp 10a, and the uneven brightness caused by the lamp insertion hole of the reflector 10b and the power supply line (not shown). The shape is good.

Further, a light scattering portion can be formed directly on the convex lens side or the back side of the emission side lens array 11b in the integrator lens 11. In the example shown in FIG. 3, light scattering portions are obtained by forming minute irregularities on the convex lens surface. Further, in this example, not all the convex lenses are light scattering portions, but light scattering portions are formed only on the convex lenses selected according to the uneven brightness of the light source 10. Like the light scattering glass plate 1, the light scattering portion in the emission side lens array 11b can be polished with coarse polishing sand or chemically formed by etching. However, in these methods, since the light scattering means is obtained by processing after forming the lens array, the number of steps is increased, and in particular, in the polishing method, the roughness of the unevenness becomes uneven, or the fineness is reduced to only the desired convex lens. There is dissatisfaction that it is difficult to form irregularities, and dissatisfaction that the etching method increases costs. Therefore, in this embodiment, the light-emitting side lens array 11b is provided with the light scattering means by being formed by a mold having minute irregularities on the inner wall surface of the cavity. According to this, since it is not necessary to provide a separate optical member as the light scattering means, the number of parts can be reduced. Further, since the light scattering means can be obtained at the same time as the molding, the man-hour can be reduced and the roughness of the fine irregularities can be reduced. Uniformity, facilitation of forming minute irregularities on a desired convex lens, and cost reduction can be achieved.

The condensing lens 12 can also be provided with a light scattering means directly like the exit lens array 11b. In this case, the same advantages as described above can be obtained.

[0024]

As described above, in the projection type image display apparatus of the present invention, light having uneven brightness emitted from the light source is dispersed by the light scattering means. Since light with reduced brightness unevenness is applied to the bulb, color unevenness, which is particularly likely to occur in a three-panel type liquid crystal projector, can be reduced and color reproducibility can be improved. When the number of convex lenses in the lens array of the integrator lens is 30 or less, the effect of the dispersion is remarkably obtained. Further, even in a configuration in which a total reflection mirror is provided between the incident-side lens array and the output-side lens array, the effect due to the dispersion is remarkably obtained. If the light-emitting side lens array is formed by molding with a light scattering means, it is not necessary to provide a separate optical member as the light scattering means, so that the number of parts can be reduced. Further, since the light scattering means is obtained simultaneously with the molding, the number of steps can be reduced, the degree of light scattering can be made uniform, and the yield is improved, as compared with the case where the light scattering means is obtained by processing after molding. If the light scattering means is provided in a part of the effective light passage area, unnecessary dispersion can be prevented. In particular, if the part has a shape corresponding to the shape of the uneven brightness of the light source, the effect of dispersion can be more remarkably obtained.

[Brief description of the drawings]

FIG. 1 is a plan view showing an optical system of a liquid crystal projector according to an embodiment of the present invention.

FIG. 2 is a view showing an embodiment of the present invention, and is an explanatory view showing an example of a light scattering glass plate.

FIG. 3 is a view showing an embodiment of the present invention, and is a perspective view showing an example of an emission-side lens array.

FIG. 4 is a view showing an embodiment of the present invention, and is an explanatory view for explaining the function of the light scattering glass plate.

FIG. 5 is an explanatory diagram illustrating a limitation on the number of convex lenses determined by a distance between an incident side lens array and an exit side lens array in an integrator lens.

FIG. 6 is a plan view showing an optical system of a conventional liquid crystal projector.

FIG. 7 is a plan view showing another optical system of the conventional liquid crystal projector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light-scattering glass plate 10 Light source 11 Integrator lens 11a Incident side lens array 11b Exit side lens array 12 Condensing lens 13 Total reflection mirror 24 Dichroic prism 25 Projection lens 31 Liquid crystal panel 32 Liquid crystal panel 33 Liquid crystal panel

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H088 EA14 HA13 HA21 HA24 HA25 HA28 MA04 MA16 MA20 5C060 AA00 BA04 BA09 BC05 BD02 GA02 HC01 HC09 HC14 HC21 JA11 JA14 5G435 AA01 BB12 BB17 CC09 DD09 FF06 HH04 LL15

Claims (6)

[Claims] 1. A light valve that modulates irradiated light, a light source that emits the light, and an incident-side lens array and an emission side such that individual convex lenses guide light from the light source to the entire surface of the light valve. A projection-type image display device including an integrator lens having a lens array, and a condenser lens provided on the light emission side of the emission-side lens array, from just before the emission-side lens array. A projection type image display device, comprising a light scattering means for scattering light immediately after the condenser lens. 2. The projection display apparatus according to claim 1, wherein the number of convex lenses in each lens array is 30 or less. 3. The projection type image display device according to claim 1, further comprising a total reflection mirror on an optical path between the incident side lens array and the exit side lens array. Projection type video display device. 4. The projection-type image display device according to claim 1, wherein the emission-side lens array is formed by a mold having minute irregularities on a cavity inner wall surface. A projection display apparatus comprising the light scattering means. 5. The projection type image display device according to claim 1, wherein said light scattering means is provided in a part of an effective light passage area. Display device. 6. The projection display according to claim 5, wherein the light scattering means provided on the part has a shape corresponding to the uneven brightness of the light source. apparatus.