JPH10171019A - Auxiliary image forming device for illumination - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the substantial fetching angle of illumination flux from a light source reducible without lowering the illumination efficiency, by coupling principal rays emitted from a set of auxiliary image forming devices to a principal ray made incident on an aperture part and coupling the principal rays emitted from the respective auxiliary image forming devices to the principal ray made incident on another auxiliary image forming device. SOLUTION: The principal ray emitted from the light source within the range of ±(45 deg. to 90 deg.) to a right side is reflected on a reflection optical element 1ba- 1, reflected on a reflection optical element 1ba- 2 besides and condensed near the virtual center of the light source. Besides, the principal rays emitted from the auxiliary image forming devices and passed through the virtual center are coupled to the principal ray directly emitted through the aperture part 1c. The principal ray emitted from the light source within the range of ±(90 deg. to 135 deg.) is condensed near the virtual center of the light source within the range of ±(45 deg. to 90 deg.) after it is reflected on a reflection mirror 1bb. Then, it is coupled to the principal ray made incident on the reflection mirror 1ba- 1 from the light source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary imaging device for illumination which is used as a part of an illumination section which requires a light beam having a high efficiency and a small opening angle.

[0002]

2. Description of the Related Art One of the present applicants is PCT / JP96 /
In 01767, one form of a projection display device was proposed. Among them, for the illumination part, which is one of the basic components of the projection display device, the relationship between the control of the angle of luminous flux from the light source, the illuminance distribution, and the direction, and their control using optical elements A proposal for specific means for realizing the above was made.

FIG. 5 shows a typical embodiment among them. In the figure, a light source 1a is composed of a discharge lamp such as a metal halide lamp. A principal ray emitted from a virtual center of the light source (for example, a mechanical center between two electrodes) is reflected by a first reflecting mirror 1c that performs both the control of the taking-in angle and the distribution, and enters the direction control lens 1d. Next, the direction control lens 1
The light beam that has passed through d is converted into two integrators 1e and 1f and a condenser lens 1g that constitute the shape conversion subgroup.
Then, the target image forming unit 2 is irradiated. The image forming unit 2 is composed of a condenser lens such as 2a and 2c and a passive image forming apparatus 2b serving as an optical switching element such as a transmissive TN liquid crystal. The light beam selectively reflected or transmitted by the operation of the image forming unit 2 is enlarged and projected on the screen by the operation of the image forming unit 3. The specific configuration of the image forming unit 2 and the types of its elements (including the transmission type and the reflection type) and the specific configuration of the image forming unit 3 are not essential to the present invention, and a description thereof will be omitted. I do.

In this embodiment, it should be noted that
In addition to the first reflecting mirror 1c, there is provided a spherical reflecting mirror 1b as an auxiliary imaging device that plays a role in taking in a part of the light beam from the light source and returning it to the light source again. This spherical reflecting mirror substantially reduces the opening angle of the light beam directly taken in by the first reflecting mirror 1c from the light source, and reduces the opening angle of the light beam illuminating the image forming unit 2b without sacrificing the illumination efficiency. Having. As described in PCT / JP96 / 01767, the following quantity I = dxdydpdq for the luminous flux emitted from the light source is always kept constant. Therefore, when the area dxdy of the portion to be illuminated is constant, dpdq corresponding to the divergence angle of the luminous flux there is naturally determined. That is,
When the size of the light source is fixed and the area to be irradiated dxdy is designated, it is necessary to reduce the opening angle of the light beam taken in from the light source in order to reduce the opening angle of the light beam there. On the other hand, if the take-in angle is simply reduced, the use efficiency of the luminous flux decreases, so some trick is required. The use of the spherical reflecting mirror 1b is one of them.

Another example of the embodiment of the auxiliary imaging apparatus of PCT / JP96 / 01767 is shown in FIG. 6 as a bird's-eye view. oo indicates an optical axis, and the discharge lamp 1a is placed so that electrodes are orthogonal to the optical axis. The light source 1a is surrounded by two reflecting mirrors 1ba and 1bb, and has an opening 1bd in front. Part of the light beam emitted from the light source 1a is directly emitted from the opening 1bd. Other light beams are reflected by the reflecting mirror a plurality of times and then emitted from the opening 1bd. The image magnification of the light flux returning from the light source to the light source 1a via the reflecting mirrors 1ba, 1bb is about 2. This example illustrates another possibility for reducing the angle of capture from the light source without reducing illumination efficiency.

[0006]

SUMMARY OF THE INVENTION The present invention relates to PCT / J
The concept of the auxiliary imaging device of P96 / 01767 was developed to clarify the specific requirements for reducing the actual angle of taking in the luminous flux from the light source without lowering the illumination efficiency, and to satisfy the given conditions. It is intended to provide means for constructing a suitable auxiliary imaging device.

[0007]

According to the first aspect of the present invention, there is provided an illuminating device including a light source and a reflection optical element for controlling a take-in angle of a principal ray emitted from a virtual center of the light source, or an illuminating device having an opening. A first reflection optical element that captures and reflects the principal ray from the virtual center of the light source and a second reflection ray that receives and reflects the principal ray from the first reflection optical element and returns the principal ray to the vicinity of the virtual center. At least one set of auxiliary imaging devices composed of at least two optical elements of the reflection optical element is provided, and the main light incident on the reflection angle controllable reflection optical element or the opening is provided with one set of auxiliary imaging devices of the auxiliary imaging device. At the same time as the rays combine, the exit chief ray from each auxiliary imaging device couples with the incident chief ray to any other auxiliary imaging device.

According to the second aspect of the present invention, the first reflecting optical element of at least one set of the auxiliary imaging device of the illuminating device crosses in the traveling direction of the principal ray reflected by the first reflecting optical element. It has a function of controlling the spatial distribution of chief rays on the provided virtual plane.

According to the third aspect of the present invention, the absolute value of the imaging magnification of the auxiliary imaging device of the illumination device is substantially 1.

According to the fourth aspect of the present invention, the first reflecting optical element and the second reflecting optical element of the auxiliary imaging device of the illumination device are the same element optical element.

According to the fifth aspect of the present invention, the illumination device includes the spherical reflecting mirror having the virtual center of the light source as its center.

According to a sixth aspect of the present invention, the principal rays from the first reflecting optical element to the second reflecting optical element of the auxiliary imaging device of the illumination device cross each other.

According to the seventh aspect of the present invention, the light source of the illuminating device is constituted by a discharge lamp having two electrodes, and all the reflection optical elements have a rotationally symmetric shape with the electrode direction as its rotation axis. The corresponding reflecting surfaces of the two reflecting optical elements constituting the auxiliary imaging device are arranged on one side in a section including the rotation axis.

[0014]

By providing a number of sets of auxiliary imaging devices corresponding to the required opening angle of the illumination light beam, the opening angle of the light beam emitted from the light source can be set to an arbitrary size.

By controlling the distribution of the principal ray with the first reflecting optical element of the auxiliary imaging device, it is possible to control the final light beam distribution of the emitted light beam.

By setting the magnification of each auxiliary imaging device to approximately one, vignetting of a light beam due to, for example, an electrode or the like caused by passing through a light source a plurality of times can be prevented, and angle consistency can be maintained. Further, it is possible to eliminate a difference due to a light beam passing path.

In addition to constructing a closed loop with two independent optical elements, it is possible to utilize the reflections of different parts of the same optical element as well as a spherical mirror as appropriate.

By intersecting the chief rays, the ratio of the space where the light flux is provided in the intermediate portion is generally reduced, and for example, it is possible to reduce the mechanical interference between the light source and the light flux.

By forming a closed loop on one side of the rotating shaft, vignetting of the light beam by the lamp itself can be prevented.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic concept of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a first embodiment of the present invention. The light source 1a is a discharge lamp having two electrodes, and is arranged such that the electrodes are perpendicular to the paper surface. 1
aa is the virtual center of the light source, and in this embodiment, is the center of gravity of the light beam. An opening 1c is provided on the right side of the figure.
A chief ray emitted within a solid angle of ± 45 ° to the right from the virtual center of the light source passes directly through the opening and exits. The reflecting optical elements 1ba_1 and 1ba_2 constitute a set of auxiliary imaging devices, and are reflecting mirrors that pass through the virtual center and have a rotationally symmetric shape about an axis in the horizontal direction on the paper surface. Similarly, the reflection optical element 1bb is also a reflection mirror having a rotationally symmetric shape about the same axis.

The principal ray emitted from the light source in the range of ± 45 ° to 90 ° on the right side is reflected by the reflection optical element 1ba_1 and travels to the reflection optical element 1ba_2. Further, the light is reflected by the reflection optical element 1ba_2 and is collected near the virtual center of the light source. Here, each shape is determined so that the opening angle of the light beam emitted from 1ba2 is equal to the take-in angle by 1ba_1, so that the imaging magnification is almost 1.
As described above, a closed loop of the light beam by the two reflecting optical elements is formed, and the principal ray that has exited the auxiliary imaging device and passed through the virtual center is connected to the principal ray that directly exits through the opening 1c. On the other hand, each principal ray reflected by 1ba_1 intersects before reaching 1ba_2. As a result, the area occupied by the light beam in the intermediate portion is reduced as is apparent from the drawing, and it is possible to prevent interference with the light source 1a. By the way, the chief ray emitted from the light source between ± 90 ° and 135 ° is reflected by the reflecting mirror 1bb, and is reflected by the same 1bb on the opposite side of the sectional view. Light is collected in the range of 45 ° to 90 °. Accordingly, the light is coupled with the principal ray incident on the reflecting mirror 1ba_1 from the light source. A closed loop of the above two principal rays starting from the virtual center of the light source, that is, 1ba_1 to 1ba_2 and 1bb to 1bb
As a result, all the light beams emitted from the light source are finally emitted within the range of ± 45 ° solid angle through the opening 1c. The light beam reflected at 1bb also has a shape such that the principal rays cross each other.

As apparent from the above configuration, the light beam finally emitted through the opening 1c includes light beams having different numbers of times of passing through the light source. First, the number of times the light beam emitted in the ± 45 ° direction from the virtual center 1aa of the light source passes through the light source is zero. A light beam in the direction of ± 45 ° to 90 ° passes through the light source once. The light beams in the directions of ± 90 ° to 135 ° pass through the light source twice. The luminous flux in the ± 135 ° to 180 ° direction is
It passes through the light source three times for convenience. In the case of a discharge lamp as in the present embodiment, a light bulb decreases as the number of times of passage increases because a normal bulb or an electrode exists near the virtual center of the light source.
One factor is the reflection by the bulb. If possible, it is desirable that the tube itself be configured as in the present embodiment, but since the tube itself becomes extremely hot, it is difficult to apply a treatment such as a reflection film or an anti-reflection film. Therefore, in the case of a light source having a separate bulb, a light flux is reduced due to Fresnel reflection determined by the refractive index of glass. The second factor is vignetting due to the electrodes. Metal halide lamps and the like have the highest brightness near the electrodes, and are therefore relatively susceptible to deviations in the adjustment of the optical system, magnification, and aberrations of the optical system. Therefore, it is desirable to set the magnification of the optical system to approximately 1.

Next, a second embodiment of the present invention is shown in FIG. The basic structure is the same as that of the first embodiment. The major difference is that the luminous flux emitted from the opening is further narrowed to a range of ± 30 °, and the number of sets of auxiliary imaging devices is correspondingly increased. Reflective optical element 1b
a_1 and the reflective optical element 1ba_2 are a set of auxiliary imaging devices, and constitute a closed loop relating to a light beam emitted in the range of ± 30 ° to 60 °. Reflective optical elements 1bb_1 and 1bb
b_2 is another set of auxiliary imaging devices, from ± 60 ° to ± 9
A closed loop is formed for a light beam emitted in the range of 0 °. The light beam emitted from 1bb_2 is connected to the light beam incident on 1ba_1, and the light beam emitted from 1ba_2 is connected to the light beam incident on the opening 1c. The light beam emitted in the range of ± 90 ° to 120 ° is directly returned to the light source by the spherical reflecting mirror 1bc, and is connected to the light beam incident on 1bb_1. In the same manner as in the first embodiment, all the connections are completed as described above, and the light beam emitted from the light source is finally emitted to the opening of ± 30 °.

FIG. 3 shows a third embodiment of the present invention. Also in this embodiment, the light source 1a uses a discharge lamp having two electrodes. The difference from the above two embodiments is that the electrodes are arranged in the plane of the paper. Reflective optical element 1c
Is a rotationally symmetric surface whose optical axis is in the direction of the electrode, and serves as an outlet for a light beam from the light source 1a instead of the opening in the above-described embodiment. Reflective optical elements 1ba_1 and 1ba_
Numerals 2 are rotationally symmetric surfaces each having the optical axis as an axis, and constitute a set of auxiliary imaging devices. In the paper, the right side of the optical axis is used as an angle reference. At this time, it is assumed that the light source 1a of this embodiment emits most of the light beam in the range of ± 45 ° to 135 °. The reflection optical element 1c is a virtual center 1a of the light source.
A light beam of ± 45 ° to 75 ° is extracted from the principal ray emitted from a. The principal ray emitted in the range of ± 75 ° to 105 ° is reflected by the reflecting mirror 1ba_1 and travels to the reflecting mirror 1ba_2. The light is further reflected by the reflecting mirror 1ba_2 and returned to the vicinity of the virtual center 1aa of the light source. This chief ray is the virtual center 1
aa and is coupled with the principal ray traveling toward the reflecting mirror 1c. With the above, all closed loops are completed and ± 4
The light beam emitted in the range of 5 ° to 135 ° is reflected by the reflecting mirror 1c.
Inject through What is characteristic in the present embodiment is that all the closed loops related to the light beams by the first and second reflective optical elements constituting the auxiliary imaging device are performed on one side of the optical axis. This is because, unlike the above two embodiments, since the electrode direction of the light source is located in the plane of the paper, when the light beam is transferred across the optical axis, the light source itself may be vignetted. is there.

As a last example, a fourth embodiment of the present invention is shown in FIG. This example has substantially the same configuration as that of the third example, except that the light beam taking-in angle is increased to ± 30 ° to 150 °. As in the third embodiment, a light beam is emitted through the reflective optical element 1c. The divergence angle of the light beam that the reflecting optical element 1c directly takes in from the light source is ± 30 ° to 60 °. The reflecting optical elements 1ba_1 and 1ba_2 constitute a set of auxiliary imaging devices, and light beams are connected on one side of the optical axis as in the third embodiment. The reflective optical element 1ba_1 captures a light beam of ± 60 ° to 90 ° emitted from the virtual center 1aa of the light source 1a. Between the reflection optical elements 1ba_1 and 1ba_2,
A spherical reflecting mirror 1bc is provided to take in a light beam of ± 90 ° to 120 ° and return it to the virtual center. With the above configuration, all the closed loops are completed, the light beam from the light source 1a is collected between ± 30 ° and 60 °, and the reflection optical element 1a is collected.
Inject through c.

The specific concept of the present invention has been described with reference to the four embodiments. The gist of the present invention is to narrow the emission angle of the light beam finally extracted from the light source without lowering the illumination efficiency by forming a closed loop of the light beam by the reflective optical element.
In an actual application, vignetting due to the electrode of the light source, Fresnel reflection of the tube, the reflectance of each reflective optical element, loss due to the joint of each optical element, etc. occur, so practical considerations are required in application. . In each of the embodiments, description has been made centering on using a reflecting mirror as the reflecting optical element. However, it is of course possible to apply a Fresnel, a diffraction grating or the like. In particular, when the number of divisions is large and the take-in angle of each optical element is relatively small, there is no need to surround the light source with one optical element.
Such various elements can be utilized. Further, depending on the application field, a refractive optical system can be provided between the light source and the reflective optical element.

[0027]

According to the first aspect of the present invention, it is possible to obtain an illumination light beam having a high illumination efficiency and a small opening angle, and to provide various advantages in equipment to be used, and to reduce the size of the illumination device itself. , Simplification of cooling, gradual reduction of cost, and the like. According to the second aspect of the present invention, it is possible to control the brightness distribution of the emitted light beam, which is useful for uniform illumination, correction of illuminance unevenness caused by the device, and the like. According to the third aspect of the invention, it is possible to reduce the opening angle, reduce the effect of vignetting when traversing the light source, and prevent a decrease in illumination efficiency. According to the fourth and fifth aspects of the present invention, by appropriately combining such a single optical element, a rational configuration as a whole is possible. Claim 6
According to the invention, the area occupied by the light flux between the reflections is reduced, and the vignetting or the like due to the tube can be minimized. According to the invention of claim 7, it is possible to prevent a vignetting of a light beam by the light source itself, and to obtain a compact and highly efficient lighting device.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a sectional view of a second embodiment of the present invention.

FIG. 3 is a sectional view of a third embodiment of the present invention.

FIG. 4 is a sectional view of a fourth embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a configuration of a lighting unit illustrated in FIG. 7 of PCT / JP96 / 01767.

6 is a cross-sectional view illustrating a configuration of a lighting unit described in FIG. 20 of PCT / JP96 / 01767.

[Explanation of symbols]

Reference Signs List 1 illumination unit 1a light source 1aa virtual center of light source 1b 1d 1e 1f 1g optical element of illumination unit 1c optical element of illumination unit or opening 1ba 1bb 1bc optical element of auxiliary imaging device 1bd opening 1ba_1 1bb_1 Construct auxiliary imaging device First
Optical element 1ba_2 1bb_2 of the second constituting the auxiliary imaging device
2 Optical element of image forming section 2a 2c Optical element of image forming section 2b Image forming apparatus 3 Image forming section 3a 3b 3d 3e Optical element of image forming section 3c Aperture stop

Claims (7)

[Claims] 1. A light source and an angle-controllable reflection optical element for taking in a principal ray emitted from a virtual center of the light source, or a lighting device having an opening, the first principal ray taking in and reflecting the principal ray from the virtual center of the light source. Auxiliary imaging device comprising at least two optical elements of a second reflecting optical element that receives and reflects the principal ray from the first reflecting optical element and the first reflecting optical element and returns the principal ray near the virtual center. And at least one set of the principal light incident on the reflection angle control element or the opening is coupled to the principal light emitted from one set of auxiliary imaging devices. And an illumination device, which is coupled to a chief ray incident on any one of the auxiliary imaging devices. 2. The illuminating device according to claim 1, wherein the first reflecting optical element of at least one set of auxiliary imaging devices is provided on an imaginary plane provided transversely to a traveling direction of a principal ray reflected by the first reflecting optical element. The illumination device according to claim 1, wherein the illumination device has a function of controlling a spatial distribution of a principal ray of the illumination light. 3. An auxiliary imaging device for the illumination device,
2. The illumination device according to claim 1, wherein the absolute value of the imaging magnification is substantially 1. 4. An auxiliary imaging device for the illumination device,
The lighting device according to claim 1, wherein the first reflecting optical element and the second reflecting optical element are the same optical element. 5. The illuminating device according to claim 1, wherein the illuminating device includes a spherical reflector having the virtual center of the light source as its center. 6. An auxiliary imaging device for the illumination device,
The illumination device according to claim 1, wherein principal rays traveling from the first reflective optical element to the second reflective optical element cross each other. 7. A light source of the illuminating device is constituted by a discharge lamp having two electrodes, all the reflective optical elements have a rotationally symmetric shape with the electrode direction as a rotation axis, and constitute an auxiliary imaging device. The lighting device according to claim 1, wherein the corresponding reflecting surfaces of the two reflecting optical elements are arranged on one side in a cross section including the rotation axis.