JP2001133884A - Illumination optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize miniaturization, to make light utilization efficiency high and to reduce the unevenness of brightness in an illumination optical device. SOLUTION: This device is provided with a light source 1, a concave mirror 2 arranged at the rear of the light source 1, a single optical path conversion lens 3 converting luminous flux in a light condensing direction emitted from an exit aperture part to nearly parallel beams, and a lens array part 5 constituted by arranging a plurality of small lenses 4 in an array state. By arranging the lens array part 5 on the emission side of the lens 3, the parallel beams are divided, a light source image is enlarged and an illumination area 10 is irradiated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical device.

[0002]

2. Description of the Related Art As an illumination optical device used for a projector, for example, the one shown in FIG. 9 is conventionally used. In this conventional example, an illumination optical device A includes a light source 1 and a concave mirror 2 such as an elliptical reflecting mirror or a parabolic reflecting mirror, and transmits a light beam emitted from a lamp (light source 1) to the concave mirror 2.
And illuminates the illumination area 10. As the light source 1, a halogen lamp, a metal halide lamp, a UHP lamp, or the like is used.

However, in this conventional example, FIG.
As shown in (2), when an elliptical reflecting mirror is used as the concave mirror 2, the light-collecting efficiency of the light source 1 is large, but there is a problem that the light flux density near the optical axis is high and the brightness unevenness of the illumination area 10 is large. . Further, as shown in FIG. 9B, even when a parabolic reflecting mirror having a lower light-collecting efficiency than the elliptical reflecting mirror is used as the concave mirror 2, the problem that the vicinity of the optical axis becomes bright is avoided. There is a disadvantage that it cannot be done.

In order to solve such a problem, an illumination optical device A using an integrator system using a lens array shown in FIG. 10 has been proposed. This illumination optical device A includes:
The first lens array 11, the second lens array 12, and the condenser lens 13 are arranged on an optical path from the concave mirror 2 to the liquid crystal panel (illumination area 10). The light beam reflected by the concave mirror 2 is split into partial light beams by the first lens array 11 and condensed on the opening of the second lens array 12. Each lens constituting the second lens array 12 forms an image of the opening of the first lens at a desired position, and
It is superimposed on the liquid crystal panel 10 by the condenser lens 13. Thereby, not only the illuminance is increased, but also the illuminance uniformity on the irradiation surface can be improved in order to superimpose various light beams.

However, in this conventional example, since two lens arrays are used, the efficiency may not be reduced and the illuminance may not be uniform due to the positional deviation of the lens arrays and the accuracy of the aperture shape during assembly. However, there is a disadvantage that the manufacturing efficiency of the apparatus is low and the manufacturing cost is high.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned drawbacks, and has a small size.
Further, an object of the present invention is to provide an illumination optical device that has high light use efficiency and can reduce uneven brightness. Further, another object of the present invention is to provide an illumination optical device capable of achieving high manufacturing efficiency of the device and reducing the manufacturing cost, and an optical element for the illumination optical device that can be used for the illumination optical device.

Still another object of the present invention is to provide a projector with high manufacturing efficiency and low manufacturing cost.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is provided a light source, a concave mirror disposed behind the light source, and a light beam in a light-collecting direction emitted from an exit opening is converted into a substantially parallel light beam. A single optical path changing lens 3 and a plurality of small lenses 4
And a lens array section 5 in which
This is achieved by arranging the lens array unit 5 on the exit side of the single optical path conversion lens 3 to provide the illumination optical device A that divides the parallel light beam and enlarges the light source image to illuminate the illumination area 10. Is done.

The irradiation light from the light source 1 is incident on the single optical path conversion lens 3 together with the reflected light from the concave mirror 2, and the light is converted into a substantially parallel light before being incident on the lens array unit 5. In the present specification, the “single optical path conversion lens 3” corresponds to a lens array composed of a plurality of small lenses 4 described later, and is formed integrally as a whole, and the emission angle with respect to the incident angle is substantially continuous. Is used as a generic term for lenses that change to. Therefore, the structural unity is not strictly required, and a compound lens or the like formed as a whole is also included as long as the output angle with respect to the incident angle changes substantially continuously as a whole. As the single optical path conversion lens 3, a plano-concave lens can be used.

The lens array section 5 has small lenses 4 arranged in an array. For example, the lens array section 5 may be configured as a lens array in which a plurality of small lenses 4, 4,. Alternatively, a plurality of small lenses 4 can be directly fixed to the single optical path conversion lens 3. A plano-concave lens is used as the small lens 4, and as described later, an appropriate number of convex lenses can be included.

The light source 1 can be a halogen lamp, a metal halide lamp, a xenon lamp, or a UHP lamp, and the concave mirror 2 can be an elliptical reflecting mirror or a spherical reflecting mirror.

As shown in FIG. 1A, a light beam emitted from a light source 1 is reflected by a concave mirror 2 provided behind the light source 1 and emitted forward. The light source 1 is arranged at a substantially focal position on the side closer to the concave mirror 2. The emitted light beam is condensed at a focal position farther from the concave mirror 2, but the single optical path conversion lens 3 is arranged to convert the light beam to be condensed into a slightly converged substantially parallel light beam. This slightly converged almost parallel light beam is
As shown in FIG. 1B, the light source image is enlarged using the lens array unit 5, and the light emitted from each small lens 4 is overlapped in the illumination area 10.

Since the slightly converged substantially parallel light beam has a large variation in the light emission angle toward the center, the image size changed by the lens array unit 5 near the center has a large effect on the distribution of the illumination area 10 and the light use efficiency. Contribute. As a result,
The light use efficiency can be increased, and the unevenness in brightness can be reduced. Further, the lens array section 5 only needs to be configured at one location, and does not require positional accuracy as in the integrator optical system shown in FIG. Moreover,
Since the number of parts is small, it is possible to improve the manufacturing efficiency of the device and reduce the manufacturing cost.

Further, the illumination optical device A can include a second concave mirror 6 which is arranged to face the reflecting portion 3b of the concave mirror 2 and has an opening at the center. As the second concave mirror 6, a spherical reflecting mirror can be used, and the light source 1 is arranged so as to occupy a substantially central position. Therefore, according to the above configuration, among the light beams emitted from the light source 1, the light beam emitted forward can also be used as effective light, so that the efficiency of capturing the light beam increases.

The lens array section 5 can be composed of a small concave lens 4a and a small convex lens 4b.
The small convex lens 4b is desirably arranged around the lens array unit 5, and the small concave lens 4
a is arranged. The peripheral small convex lens 4b refracts a light beam to be emitted from the lens array section 5 to the outside of the irradiation area into the irradiation area, so that the light use efficiency is improved and
The luminous flux is supplied to the outer peripheral portion of the irradiation area to prevent the occurrence of uneven light from the central portion.

Further, in the illumination optical device A, a plurality of small lenses 4 are arranged in an array on the rear side flat wall of the single optical path conversion lens 3 which converts a received light beam from a curvature surface into a substantially parallel light beam and transmits the same. An optical element B for an illumination optical device integrally formed can be used.

The optical element B for the illumination optical device is provided with a small lens 4 in advance on the single optical path conversion lens 3 of the illumination optical device A.
Are integrally formed in an array. Therefore, when configuring the illumination optical device A described above, the single optical path conversion lens 3 and the lens array unit 5 can be configured only by disposing the optical element B for the illumination optical device in front of the concave mirror 2. The labor and cost for manufacturing can be reduced.

The curvature surface of the single optical path conversion lens 3 is
A light-transmitting light beam from the curvature surface is converted into a substantially parallel light beam, and the light-transmitting portion is formed at a central transmitting portion 3a through which the light is transmitted;
An optical element B for an illumination optical device that is partitioned into a reflecting portion 3b that reflects the received light beam in the light receiving direction can be configured.

The plane of curvature of the plano-concave lens is the central transmitting portion 3a.
And a reflection part 3b surrounding this. The reflecting portion 3b can be formed by forming a reflecting film on a curved surface that reflects the light flux emitted from the light source 1 toward the light source 1, and is preferably formed in a spherical shape with the light source 1 as a center. In the optical element B for the illumination optical device, the reflecting portion 3b functions as the second concave mirror 6, and the structure can be further simplified.

Further, the optical element B for the illumination optical device
Can be configured as an optical element C for a projector by forming a film of an ultraviolet ray and an infrared ray cut filter 7 on the received light beam transmitting portion 3a of the plano-concave lens. A filter 7 for blocking ultraviolet and infrared rays is formed in a film on a light-receiving beam transmitting portion 3a of a plano-concave lens that transmits a received light beam and converts incident light into a substantially parallel light beam. To be able to prevent
There is no need to separately arrange a filter, and the number of manufacturing steps and cost can be reduced.

Further, the above-mentioned illumination optical device A, optical element B for illumination optical device, and optical element C for projector emit light from a light source 1, a concave mirror 2 disposed behind the light source 1, and an exit opening portion. After converting the light beam in the converging direction into a substantially parallel light beam, the parallel light beam is converted into a plurality of small lenses 4.
Light forming optical system D for further splitting into parallel light beams by
And a projector having an image forming means 8 for modulating a light beam from the parallel light forming optical system D to form an image and a projecting means 9 for enlarging and projecting the image formed by the image forming means 8. .

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, an illumination optical apparatus A includes a light source 1 and a concave mirror 2 disposed behind the light source 1.
A second concave mirror 6 disposed opposite the reflecting surface of the concave mirror 2, and a parallel mirror disposed facing the exit opening of the light source device formed by the light source 1, the concave mirror 2, and the second concave mirror 6. And a light forming optical system D. It is desirable to use a light source 1 having a light-emitting point close to a point, such as a halogen lamp, a metal halide lamp, or a xenon lamp. In this embodiment, a UHP lamp having an arc length of 1.5 mm is used. A parabolic reflecting mirror or an elliptical reflecting mirror can be used for the concave mirror 2, but an elliptical reflecting mirror is desirably used in order to increase the utilization efficiency of the light flux. In this embodiment in which the elliptical reflecting mirror is used as the concave mirror 2 and the spherical reflecting mirror is used as the second concave mirror 6, the relationship between the light source 1 and these concave mirrors 2 and the second concave mirror 6 is as follows. The second concave mirror 6 is determined to be located substantially at the focal point on the side closer to 2 and to occupy the substantially central position of the second concave mirror 6, and the opening of the second concave mirror 6 becomes an exit opening emitted from the light source device.

The parallel light forming optical system D includes a single optical path changing lens 3 and a lens array unit 5. A plano-concave lens can be used as the single optical path conversion lens 3 and is arranged directly opposite the exit opening of the light source device. The lens array section 5 is formed by arranging a plurality of small lenses 4, 4,... In an array. The small lenses 4 are plano-concave lenses similar in shape to the liquid crystal panel 8a described later, and are arranged without any gap.

The lens array section 5 can be formed by adhering the plurality of small lenses 4 to an appropriate transparent substrate. However, as shown in FIG. An optical element B for an illumination optical device can also be configured by using a plano-concave lens as the lens 3 and fixing the plano-concave lens 3 to a rear flat wall of the plano-concave lens 3 by appropriate means. With this configuration, there is no need to separately provide a mechanism for holding the lens array unit 5, and thus assembly and the like are simplified.

FIG. 1C shows the results of an experiment conducted to verify the performance of the illumination optical device A described above. The configuration and measurement method of the illumination optical device A used in the experiment are described below.

Light source 1: UH with an arc length of 1.5 mm
P lamp ・ Concave mirror 2 ・ ・ ・ Diameter 40mm, first focal length 13m
m, elliptical reflecting mirror having a second focal length of 40 mm. Second concave mirror 6: diameter 40 mm, diameter 2 at the center.
Spherical reflecting mirror having an opening of 8 mm ・ Single optical path conversion lens 3 ・ ・ ・ Plano-concave lens 3 having a diameter of 28 mm and a radius of curvature of 30 mm ・ Lens array section 5 ・ ・ ・ A radius of curvature of 14 mm, an aperture size of 6 mm long and 8 mm wide Small concave lenses 4a composed of rectangular plano-concave small lenses are arranged in an array of 4 rows × 4 columns and adhered to the flat wall on the back side of the single optical path conversion lens 3. Measurement method: From the above-described illumination optical device A A liquid crystal panel 8a having an aspect ratio of 0.94 inches and an aspect ratio of 3: 4 was arranged in the illumination area 10 at an appropriate distance, and the brightness distribution in the illumination area 10 was measured.

As can be seen from the measurement results shown in FIG. 1C, since the light source image of the lamp 1 is enlarged by the small lenses 4, 4,... Of the lens array section 5, the central portion does not become bright, Brightness unevenness is reduced. At this time, the peripheral light amount ratio was 80%.

FIG. 2 shows the configuration of a comparative example for verifying the illumination optical device A and the measurement results. In this comparative example, the same light source device and the single optical path conversion lens 3 as those in the above-described embodiment are used, and the lens array unit 5 in the embodiment is not provided. As shown in FIG. 1 (b), even if the light beam is almost parallelized by the plano-concave lens 3, the brightness distribution shows a sharp rise at the center and the brightness unevenness is large. For comparison with the example, the measurement result of the comparative example is shown by a dashed line in FIG.

FIG. 3 shows a modification of the illumination optical device A. In the following description of the modified examples and the embodiments,
Components that are substantially the same as those in the above-described embodiment are given the same reference numerals in the drawings, and description thereof will be omitted. Further, in the following description, the case where the optical element B for the illumination optical device in which the lens array section 5 is fixed to the rear side flat wall of the single optical path conversion lens 3 is used, but the lens array section 5 is separately provided. It is also possible to configure.

In this modification, the small lenses 4 of the lens array unit 5 are small convex lenses 4b, 4
b. By forming the lens array section 5 with the small convex lens 4b, as shown in FIG. 3B, the rising of the central portion is steeper than in the above-described embodiment, but is smaller than that in the comparative example. The brightness near the center increases, and improvement in brightness unevenness can be confirmed. In addition,
For comparison, in the following description, the measurement result in the comparative example is indicated by a chain line in the figure.

FIG. 4 shows a second embodiment of the present invention.
In this embodiment, the lens array section 5 is composed of two types of small lenses 4, a small convex lens 4b and a small concave lens 4b composed of a plano-concave lens. In the example shown,
The lens array unit 5 has 4 rows × 4 columns = 16 small lenses 4,
As shown in FIG. 4 (b), a small concave lens 4b is used in the center 2 rows × 2 columns, and a small convex lens 4b is used around the rest. In FIG. 4B, the small convex lens 4b is hatched in the figure.

With the above configuration, FIG.
As shown in (c), the small concave lens 4a at the center of the lens array portion 5 greatly contributes to light use efficiency and brightness unevenness, so that the center portion does not become bright and the light use efficiency decreases. And uneven brightness can be reduced. As a result of measuring the brightness distribution with the above configuration, FIG.
Although slightly different from (c), the peripheral light amount ratio was 80%.

FIG. 5 shows a third embodiment of the present invention.
In this embodiment, the light source device is the first,
It is configured by removing the second concave mirror 6 from the second embodiment. The lens array section 5 is configured by mixing the small convex lens 4b and the small concave lens 4a in the same manner as in the above-described second embodiment, but may be configured by only the small concave lens 4a. In this embodiment, although the use efficiency of the irradiation light beam from the light source 1 is reduced, the unevenness in brightness can be reduced as shown in FIG.

FIG. 6 shows a fourth embodiment of the present invention.
This embodiment shows a modification of the single optical path conversion lens 3. The single optical path conversion lens 3 formed of a plano-concave lens is formed to have the same size as the opening of the concave mirror 2 behind the light source 1 and emits a light beam. Other than that, that is, the periphery is left as the reflection portion 3b except for the central portion. The reflecting portion 3b can be formed by depositing aluminum or the like on the curvature surface of the single optical path conversion lens 3. Therefore, in this embodiment, since the single optical path conversion lens 3 also serves as the second concave mirror 6 in each of the above-described embodiments, it is not necessary to separately arrange the second concave mirror 6. Note that the lens array section 5 can be subjected to the various modifications described above.

FIG. 7 shows a projector to which the present invention is applied. The projector includes an illumination optical device A, an image forming unit 8, and a projection lens forming a projection unit 9. The image forming means 8 includes a polarizer 8b, a liquid crystal panel 8a, an analyzer 8
c, which is emitted from the illumination optical device A and has almost no uneven brightness, is modulated by the image forming means 8 and then enlarged by the projection lens 9 to be projected on a display surface (not shown). Liquid crystal panel 8 in this embodiment
In a, a nematic liquid crystal having a positive dielectric anisotropy was sealed between two glass substrates provided with transparent electrodes forming pixels, and the long axis of liquid crystal molecules was continuously twisted by 90 ° between the two glass substrates. , 0.94 inch, aspect ratio, vertical: horizontal = 3: 4, a transmissive TN liquid crystal element is used. Active matrix driving is used for liquid crystal driving. Further, the projection lens 9 has a focus adjustment function and a zoom function. Note that an STN liquid crystal element, a ferroelectric liquid crystal element, or the like can be used for the liquid crystal panel 8a.

In this embodiment, the illumination optical device A
The single optical path conversion lens 3 uses a projector optical element C in which a received light beam transmitting portion 3a is formed with an ultraviolet and infrared cut filter 7 as a film. The projector optical element C is obtained by forming a film of the ultraviolet ray and the infrared ray cut filter 7 on the received light beam transmitting portion 3a of the single optical path conversion lens 3 in each of the above-described embodiments.
(A) or as shown in FIG. 8 (b).

Therefore, in this embodiment, since the light beam emitted from the illumination optical device A is a light beam with less uneven brightness, the light beam modulated by the liquid crystal panel 8a is converted into a light beam with less uneven brightness by the projection lens. In addition, the easy-to-view image can be enlarged and displayed. Further, when the projector optical element C is used for the single optical path conversion lens 3, it is not necessary to separately provide an ultraviolet ray and infrared ray cut filter 7, so that the manufacturing cost can be reduced.

The configuration of the projector is not limited to the configuration described above, and the projector can be configured using a reflective liquid crystal element and a digital mirror device. Further, the projector may be configured to illuminate the liquid crystal panel 8a with the respective lights obtained by separating the light flux from the illumination optical device A using a color separation means such as a dichroic mirror and further combine them to perform color display. it can.

[0039]

As is apparent from the above description, according to the present invention, miniaturization is possible, light utilization efficiency is high, and
In addition, it is possible to obtain an illumination optical device capable of reducing uneven brightness.

[Brief description of the drawings]

1A and 1B are diagrams illustrating the present invention, in which FIG. 1A is a diagram illustrating a configuration and an optical path of an illumination optical device, FIG. 1B is an explanatory diagram illustrating an operation of a lens array unit, and FIG. It is a figure showing a measurement result showing distribution of height.

2A and 2B are diagrams illustrating a comparative example, in which FIG. 2A is a diagram illustrating a configuration and an optical path of an illumination optical device, and FIG. 2B is a diagram illustrating a measurement result illustrating a distribution of light brightness in an illumination area.

3A and 3B are diagrams showing a modification of the illumination optical device, wherein FIG. 3A is a diagram showing a configuration and an optical path of the illumination optical device, and FIG. 3B is a diagram showing a measurement result showing a distribution of light brightness in an illumination area. It is.

FIG. 4 is a diagram showing a second embodiment of the present invention, in which (a)
FIG. 4 is a diagram illustrating a configuration and an optical path of an illumination optical device, FIG. 4B is a plan view of a lens array unit, and FIG. 4C is a diagram illustrating a measurement result illustrating a distribution of light brightness in an illumination region.

FIG. 5 is a view showing a third embodiment of the present invention, wherein (a)
FIG. 4 is a diagram illustrating a configuration and an optical path of an illumination optical device, and FIG. 4B is a diagram illustrating a measurement result illustrating a distribution of light brightness in an illumination area.

FIG. 6 is a diagram showing a fourth embodiment of the present invention.

FIG. 7 is a diagram illustrating a projector.

FIG. 8 is a diagram showing a modification of the projector.

FIG. 9 is a diagram showing a conventional example.

FIG. 10 is a diagram showing another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Concave mirror 3 Single optical path conversion lens 3a Transmission part 3b Reflection part 4 Small lens 4a Small concave lens 4b Small convex lens 5 Lens array part 6 Second concave mirror 7 Ultraviolet / infrared cut filter 8 Image forming means 9 Projection means A Illumination optical Apparatus B Optical element for illumination optical apparatus C Optical element for projector D Parallel light forming optical system

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H04N 5/74 F21M 1/00 R // F21Y 101: 00 F term (reference) 2H052 BA02 BA03 BA09 BA14 3K042 AA01 AC02 BB12 BC02 BC09 5C058 AA06 AB03 AB05 EA12 EA26 EA51

Claims (5)

[Claims] 1. A light source, a concave mirror disposed behind the light source, a single optical path conversion lens for converting a light beam in a converging direction emitted from an exit opening into a substantially parallel light beam, and a plurality of small lenses arranged in an array. And a lens array unit disposed on the exit side of the single optical path changing lens to divide the parallel light beam and enlarge a light source image to illuminate an illumination area. Optical device. 2. The illumination optical device according to claim 1, wherein a second concave mirror having an opening at a central portion is arranged to face the reflection surface of said concave mirror. 3. An optical element for an illumination optical device in which a plurality of small lenses are integrally formed in an array on a rear-side flat wall of a single optical path conversion lens which transmits a received light beam from a curvature surface into a substantially parallel light beam and transmits the light beam. 4. A curved surface of the single optical path conversion lens is formed at a central transmitting portion for converting a light beam received from the curved surface into a substantially parallel light beam and transmitting the parallel light beam, and at a peripheral edge of the transmitting portion. The optical element for an illumination optical device according to claim 3, wherein the optical element is partitioned into a reflecting portion that reflects light in a light receiving direction. 5. A light source, a concave mirror disposed behind the light source, and a light beam in a converging direction emitted from an exit opening portion is converted into a substantially parallel light beam, and the parallel light beam is further converted into a parallel light beam by a plurality of small lenses. A projector comprising: a parallel light forming optical system for splitting; an image forming means for forming an image by modulating a light beam from the parallel light forming optical system; and a projecting means for enlarging and projecting the image formed by the image forming means.