JPH10161029A - Polarization lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the polarization lighting device which gives light and uniform lighting and is reducible in component cost and superior in mass- productivity. SOLUTION: The light from a light source 11 is made incident on a polarization separating means 16 and then separated into P-polarized light and S- polarized light which travel straight by a polarization separating film 21 and a reflecting film 22 of a reflecting plate 18. An integrator optical system 25 changes the direction of polarized light to the P-polarized light or S-polarized light and a polarization separation body 17 is formed in the shape of a plate having projection parts 19 whose vertical angles are nearly 90 deg. formed on one surface in one body. The integral molding becomes possible without performing polishing and the manufacture cost is reducible. The mass-productivity is superior, high luminance is obtained, and the device can be constituted at low cost and is suitable to light source facilities of, for example, a projection type liquid crystal display device equipped with a light valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarized light illuminating device capable of increasing luminance.

[0002]

2. Description of the Related Art In general, a projection type liquid crystal display device projects a display image through a liquid crystal light valve, and therefore requires an illumination device which generates strong light. The light source light of such an illuminating device is a so-called random light beam having a random polarization direction, and the polarizing plate arranged on the incident side of the liquid crystal light valve causes either a P-polarized light beam or an S-polarized light beam of the random light. One of them is selected and used to project and display on the screen.

In such an illuminating device, 50% or more of the light flux of the light from the light source is absorbed by the incident side polarizing plate, so that the utilization rate of the light flux is reduced. Further, since the heat generated by the polarizing plate increases, cooling of the polarizing plate has become a major problem in designing the projection device.

Further, a configuration described in Japanese Patent Application Laid-Open No. 8-234205 is known to increase the utilization rate of the luminous flux of the light source light.

The device disclosed in Japanese Patent Application Laid-Open No. 8-234205 separates source light into two orthogonally polarized lights by using a polarization separating means, and further aligns the polarization directions of these polarized lights by an integrator optical system. Out.

[0006] In this case, the polarization separation means includes 1
One or a plurality of triangular prisms are used. These prisms have a certain thickness or more, and heat shrinkage occurs due to heat at the time of molding. Therefore, they must be manufactured by polishing. For this reason, the manufacturing cost of the prism becomes extremely high, and there is a problem in mass productivity.

[0007]

As described above, in the conventional configuration, the utilization rate of the luminous flux of the light source light is low, there is a problem of heat generation, and the polarization separation described in Japanese Patent Application Laid-Open No. 8-234205 is disclosed. In a lighting device using the means, since a triangular prism is used, the manufacturing cost is extremely high, and there is a problem in mass productivity.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a polarized light illuminating device which can provide bright and uniform illumination, can reduce parts costs, and is excellent in mass productivity. I do.

[0009]

According to the present invention, a light from a light source is separated into two orthogonally polarized lights by a polarization splitting means, and these two polarized lights are guided to an integrator optical system. In a polarized light illuminating device that emits light in the same polarization direction, the polarized light separating means includes a plate-shaped polarized light separator in which a plurality of projections each having an apex angle of substantially right angle are integrally formed on one surface, The two opposing surfaces are tapered, one surface is joined to the other surface of the polarized light separator via a polarized light separating film, and the other surface is provided with a reflecting plate on which a reflecting film is formed. Is incident on the polarization separation means, and is separated into orthogonal P-polarized light and S-polarized light by the polarization separation film and the reflection film provided on the other surface of the reflection plate, respectively. side The polarization direction is aligned to either light or S-polarized light, and furthermore, the polarization separator has a plate-like shape in which a plurality of projections each having a substantially right-angled apical angle are integrally formed on one surface. Integral molding can be performed without any processing, so that production costs can be reduced and mass productivity is excellent.

[0010]

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 11 denotes a light source. The light source 11 has a lamp 12 and a reflector 13 having a parabolic mirror surface or a semi-circular mirror surface arranged on the rear surface of the lamp 12. Is provided with a heat ray cut glass. Therefore, the light source light generated from the lamp 12 is converted into a parallel light flux by the reflector 13, and is irradiated forward through the heat ray cut glass 14.

Reference numeral 16 denotes a polarized light separating means. The polarized light separating means 16 has a plate-shaped polarized light separator 17 and a reflection plate 18 combined with the polarized light separator 17. And
On one surface of the plate-like polarized light separator 17, a plurality of wavy projections 19 each having an apex angle of approximately a right angle are integrally formed. Since the polarization separator 17 has a plate-like thin shape, the polarization separator 17 including the wavy projection 19 is integrally formed by glass or resin molding.

Further, the reflection plate 18 has two tapered surfaces facing each other, and one surface of the reflection plate 18 is joined to the other surface of the polarization beam splitter 17 via a polarization beam splitting film 21. On the other surface, a reflection film 22 is formed.
The polarization separating film 21 has a polarization characteristic of transmitting one of P-polarized light and S-polarized light of random light and reflecting the other, for example, transmitting P-polarized light and reflecting S-polarized light.

The polarized light separating means 16 is arranged at a predetermined angle with respect to the irradiation direction of the light source 11. That is, the parallel light rays from the light source 11 are incident almost perpendicularly to a substantially right side of the wavy projection 19, and the angle is set so that the taper direction of the reflection plate 18 is directed to the lower left. I have. For this reason, an angle θ is formed between the polarization separation film 21 and the reflection film 22, and the angles of the respective polarized light beams reflected to the left in the drawing are different from each other as shown in the drawing.

Further, a condenser lens 24 is provided on the output side of the polarization separating means 16, and an integrator optical system 25 is provided on the output side. This integrator optical system
Reference numeral 25 denotes a split lens 26 provided close to the condenser lens 24, an imaging lens 27 arranged opposite to the split lens 26, and a phase difference provided adjacent to the exit side of the imaging lens 27. It is constituted by a plate 28. The phase difference plate 28 is provided corresponding to the emission position of one polarized light, and rotates the polarization plane of the polarized light.

Here, the angle θ between the polarization separation film 21 and the reflection film 22 is set as follows. The imaging lens 27 is a group of a plurality of rectangular lenses.
Assuming that the width of the two lenses is D, the focal length of the split lens 26 is f, and the refractive index of the polarization separator 17 is n, the angle θ is approximately θ = (sin ⁻¹ (1 / n) sin (2tan (D / 3
f))) / 2-θ = (sin ^-1 (1 / n) sin (2tan (D / 5
f))) Set in the range of / 2.

Next, the operation of the above embodiment will be described.

First, the light source light generated from the lamp 12 of the light source 11 becomes parallel light random light by the reflector 13, the heat rays are cut off by the heat ray cut glass 14, and the light is incident on the polarization beam splitting means 16. The random light that has entered the polarization splitter 17 of the polarization splitter 16 almost perpendicularly from one side of the wavy projection 19 formed on the surface of the polarization splitter 17 is converted into two polarized lights by the polarization splitting film 21. Separated.

That is, of the random light, the P-polarized light passes through the polarization splitting film 21, and the S-polarized light is reflected by the polarization splitting film 21 at a slightly obtuse reflection angle and is emitted to the left. The P-polarized light transmitted through the polarization separation film 21 is incident on the reflection plate 18, is reflected by the reflection film 22 at a slightly acute reflection angle, and is similarly emitted to the left. That is, the emission angles of the P-polarized light and the S-polarized light are different from each other corresponding to the above-described angle θ, and are set in directions slightly intersecting as shown in the figure.

That is, the P-polarized light and the S-polarized light are in a range of 2 * tan (D / 3f) to 2 * tan corresponding to the angle θ.
They are set to intersect with an angle in the range of (D / 5f).

By tilting the optical axis of the random light from the light source 11 to the polarization splitting means 16 by about θ / 4,
The light beam angle on the exit side from the polarization splitting means 16 can be set optimally.

The P-polarized light and the S-polarized light emitted from the polarization splitting means 16 pass through a condenser lens 24 and pass through a split lens.
The light is converged to a predetermined positional relationship for each polarized light by the integrator optical system 25 of the imaging lens 26. Then, the polarization plane of the P-polarized light emitted from the imaging lens 27 is rotated by the phase difference plate 28 provided corresponding to the emission position of the P-polarized light, and is converted from the P-polarized light to the S-polarized light. Then, the light is emitted to the left toward an illumination target (not shown).

On the other hand, the S-polarized light emitted from the imaging lens 27 is emitted to the illumination object as it is because it is not subjected to the conversion effect by the phase difference plate 28. That is, the retardation plate 28 corrects and matches the 90-degree shift in the polarization direction between the P-polarized light and the S-polarized light and combines them.

Since the P-polarized light and the S-polarized light are combined in this manner, a significantly higher luminance can be realized as compared with the case where a conventional one-directional polarized light is used. In addition, when a conventional one-way polarized light beam is used, unnecessary light is absorbed by the incident-side polarizing plate, so that thermal damage is large,
Although it was difficult to increase the transmittance of the polarizing plate due to the heat generation problem, such a thermal damage can be reduced in the above embodiment, and a shift to a high transmittance type is possible.

The polarized light separating member 17 constituting the polarized light separating means 16 is a plate-like member having a plurality of corrugated projections 19 integrally formed on the surface and can be formed to be thin. Integral molding can be performed, and the manufacturing cost is much lower than that of a conventional triangular prism manufactured by polishing, and mass productivity is improved.

[0026]

According to the polarized light illuminating device of the present invention, when the light from the light source is incident on the polarized light separating means, the polarized light is separated by the polarized light separating film and the reflecting film provided on the other surface of the reflecting plate. It is separated into orthogonal P-polarized light and S-polarized light, and the polarization direction is aligned to either P-polarized light or S-polarized light by the integrator optical system.
Since a plurality of projections each having a substantially right-angled apex are integrally formed on one surface, they can be formed integrally without the need for polishing, reducing manufacturing costs and increasing productivity. It can be configured inexpensively with high brightness and can be suitably used, for example, for light source equipment of a projection type liquid crystal display device having a light valve.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a polarized light illumination device of the present invention.

[Explanation of symbols]

 11 Light source 16 Polarization separation means 17 Polarization separator 18 Reflection plate 19 Protrusion 21 Polarization separation film 22 Reflection film 25 Integrator optical system

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI G02F 1/1335 530 G02F 1/1335 530

Claims (1)

[Claims] 1. Light from a light source is separated into two orthogonally polarized lights by a polarization splitting means, and these two polarized lights are guided to an integrator optical system, and the two polarized lights are emitted in the same polarization direction. In the polarized light illuminating device described above, the polarized light separating means includes a plate-shaped polarized light separator in which a plurality of projections each having an apex angle of substantially a right angle are integrally formed on one surface, and two surfaces facing each other have a tapered shape. A polarized light illuminating device comprising: one surface joined to the other surface of the polarized light separator via a polarized light separating film; and the other surface provided with a reflecting plate on which a reflecting film is formed.