JPH08160351A - Projection type optical device - Google Patents

Abstract

PURPOSE: To efficiently utilize light from a light source so as to improve the brightness of a picture on a screen by providing a retroreflecting means reversely reflecting light on an area where the light does not become a parallel luminous flux toward the light source out of the light radially emitted from the light source. CONSTITUTION: The retroreflecting part 31 is disposed between the light source part 11 and an optical system 12, and also a retroreflecting part 32 is provided near the back surface side end of a dichroic mirror 121-1 of the optical system 12 faced to the light source part 11. The part 31 is obtained by forming a retroreflecting member 21 in which the spherical beads of glass, etc., having high refractive index are laid by two or three layers and covered with acrylic resin, etc., as a cylindrical shape having nearly the same diameter as that of the parallel luminous flux emitted from the light source part 11, and both of light L3 toward the part 31 and light L4 toward the part 32 are reversely reflected by the parts 31 and 32 and returned to the light source 112, so that they enter an optical system as the parallel luminous flux L' as they are. Consequently, the picture on the screen can be bright without using a mirror having a concave spherical surface requiring many man-hours in the case of manufacturing and attaching it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type optical device, such as a projector in the field of liquid crystal displays, which transforms light from a light source into a parallel light beam, performs a required process, and then enlarges and projects it on a predetermined screen. The present invention relates to a projection type optical device in which productivity is improved by improving workability by constructing the optical device such that light radially emitted from the device is made into a parallel light flux without waste and the projection light on the screen becomes bright.

[0002]

2. Description of the Related Art FIG. 4 is a diagram schematically showing a configuration of a projection type optical device, FIG. 5 is a diagram explaining a configuration example of a conventional projection type optical device, and FIG. It is a figure explaining a problem.

In the drawings, the case where the projection type optical device is a liquid crystal color display projector will be described as an example. In FIG. 4, the projection type optical device 1 ′ is roughly classified into a light source section 11 surrounded by a chain line A, an optical system 12 surrounded by a chain line B, and a projection lens section 13 surrounded by a chain line C. Is the main part.

The internal light source unit 11 comprises a reflector 111 such as a parabolic mirror and a light source 112 such as a metal halide lamp positioned at the focal point thereof, and all the light emitted from the light source 112 in the reflector direction is reflected by the reflector 111. After being reflected by the light source 11, a parallel light beam L'is emitted from the light source unit 11.

A light-shielding portion 112a is formed at the apex region on the optical system side of the light source 112 so that at least direct light from the light source cannot reach the optical element in the optical system facing the light source. It has become.

Further, the optical system 12 guides the parallel light flux L ₁ from the light source section 11 to dichroic mirrors 121 _-1 and 121 _-2 to decompose it into three primary color lights of R, G and B, and then the respective three primary colors. Liquid crystal panel for three primary colors as a projection object located on the light beam 1
The color light intensities are modulated by 22 _-1 , 122 _-2 , 122 _-3 , and then color combination is performed by the dichroic mirrors 121 _-3 and 121 _-4 , which can be derived as a parallel light flux L ″. is there.

The projection lens unit 13 is usually composed of a plurality of lenses in order to eliminate chromatic aberration as a lens, and all of 123 _-1 , 123 _-2 and 123 _-3 are condenser lenses. Further, 124 _-1 and 124 _-2 are mirror plates for guiding light in a predetermined direction.

In the projection type optical device 1 ', the light source 112 is used.
A part of the light radially emitted from the optical system 12 is likely to be emitted from the periphery of the reflector 111 to the outside of the optical path as indicated by an arrow D ₁ , and the light as the light source 112 cannot be effectively used. Therefore, the parallel light flux L ″ emitted from the optical system 12 As the amount of light on the screen decreases, the resulting screen
There is a defect that the image at 14 becomes dark.

In FIG. 5 for explaining a conventional projection type optical device in consideration of such a defect, (5-1) shows the whole structure, and (5)
-2) is an enlarged view of the main part of the present invention.

The projection-type optical apparatus 1 shown in FIG.
A mirror 15 in the shape of a hemispherical shell is sliced between the light source unit 11 and the optical system 12 described above. That is, the mirror 15 in this case is approximately at the distance between the light source 112 and the intersection P of the luminous flux circumferential surfaces of the _two optical paths (optical paths L ₁ and L _{2 in} the case of FIG. ₁ ) close to the light source section 11 of the optical system 12. A line connecting the light source 112 and the edge of the reflector 111 with a hemispherical shell having an equal radius R.
The area from a ₁ to the line a ₂ connecting the light source and the point P is sliced into a thickness t so as to cover it, and its inner surface is formed into a mirror surface.

Therefore, by mounting the mirror 15 on the optical axis of the optical path L ₁ in the projection type optical device 1'of FIG. 4 so that the center of the spherical shell coincides with the light source 112, the conventional projection type optical The device 1 can be configured as shown.

A projection type optical device 1 having such a mirror 15
Then, as shown in (5-2), inside the light emitted from the light source 112, the light emitted from the periphery of the reflector 111 to the outside of the optical path as shown by the arrow D ₁ in FIG. 4 is reflected by the mirror 15 as shown by the arrow D ₂ . Then, since the light is returned to the original light source 112, it can be made incident on the optical system 12 as a parallel light beam L'on the regular optical path by the reflector 111, and the light beam is not suppressed in the optical system 12 and is emitted from the optical system 12. It is possible to compensate for the above-mentioned insufficient light amount of the parallel light flux L ″.

[0013]

[Problems to be Solved by the Invention] However, such a mirror 15
In the conventional projection optical apparatus 1 having the above, it takes a lot of man-hours and cost to obtain the mirror 15 having a concave spherical surface, and at the same time, it is possible to surely perform the axis alignment and the inclination even when the projection optical apparatus 1'is mounted. However, there is a problem that productivity improvement cannot be expected in terms of price and man-hours.

In FIG. 6 for explaining the problem, a shaded area E is a line a ₂ connecting the light source 112 and the intersection P or the vicinity thereof.
The light region that can be emitted from between the light source 112 and the above-mentioned light shielding portion 112a of the light source 112 is shown. In this case, the light emitted from the light source 112 to the light region E is outside the required optical path as indicated by arrow E _1. There is a problem that the image on the screen may be darkened like the light traveling in the direction of arrow D _{1 in} FIG.

[0015]

SUMMARY OF THE INVENTION The above-mentioned problems are solved by the following: a light source section consisting of a light source and a reflector for emitting a parallel light flux; an optical system for processing the parallel light flux into a required parallel light flux; and a parallel light from the optical system. A projection type optical device including a projection lens for projecting a light flux onto a screen, the retroreflector comprising a retroreflective member for making a region of the light radially emitted from the light source, which is not converted into a parallel light flux in the light source section, back to the light source. The problem is solved by a projection-type optical device provided with a reflection means.

[0016]

When all of the light emitted from the light source except for the light directed to the reflector is reflected back to the light source, all of the light emitted from the light source can be incident on the optical system as a parallel light beam. You can then brighten the image on the screen.

On the other hand, in a resin sheet in which transparent spherical beads are covered with a transparent resin so as to be spread, incident light from any direction can be reflected in a direction opposite to that by reflection or refraction within the beads. It is used as a retroreflective member in road signs and reflectors for general signs.

FIG. 7 illustrating an example of a retroreflective member, for example.
The retroreflective member 21 having a thickness of, for example, about 0.3 mm has two spherical beads 211 having a diameter of about 50 to 100 μm and made of a material having a refractive index of about 2 or more, such as general high refractive index glass. ~ A transparent resin such as an acrylic resin having a refractive index smaller than that of the beads as spread over about 3 layers
It is formed by wrapping with 212.

In the retroreflective member 21, light incident from an arbitrary direction as shown by an arrow F ₁ can be reflected in a reverse direction as shown by an arrow F ₂ by refraction and reflection by the transparent resin 212 and the spherical beads 211. it can.

In FIG. 8 showing another example of the retroreflective member, the retroreflective member 25 having a thickness of about 0.2 mm is formed by embossing a transparent resin 251 such as an acrylic resin in a chevron shape. is there.

In the retroreflective member 25, the light incident from any direction as indicated by the arrow G ₁ is applied to the surface of the transparent resin 251.
By refraction and reflection at 25a, it can be reflected in the direction opposite to the arrow G ₂ .

Therefore, in the present invention, the retroreflective member 21 or 25 is replaced with the mirror 15 in FIG. 4, and the retroreflective member 21 or 25 is returned so that the light corresponding to the shaded area E described in FIG. 6 is returned to the light source. Is added to configure a projection-type optical device.

Therefore, it is possible to brighten an image on the screen by effectively utilizing the light emitted from the light source without waste, and as a result, it is possible to expect improvement in productivity due to improvement in workability.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view for explaining a projection type optical device according to the present invention, and like FIG. 5, (1-1) shows the whole structure.
2) is an enlarged view of the main part near the light source.

FIG. 2 is a diagram for explaining the second configuration example of the projection type optical device as the main part, and FIG. 3 is a diagram for explaining the third configuration example of the projection type optical device as the main part. Note that, in each of the drawings, the case where the invention is applied to the projection-type optical device described in FIG. 4 is taken as an example, and thus the same target members and parts as those in FIGS. Is omitted.

The projection type optical device 3 according to the present invention in (1-1) of FIG. 1 is the light source unit 11 of the projection type optical device 1'described with reference to FIG.
And the optical system 12 between the first retroreflective portion 31 according to the present invention.
At the same time as the arrangement of the light beams described above with reference to FIG. 5, in the vicinity of the rear end of the dichroic mirror 121 _-1 as an optical element facing the light source unit 11 of the optical system 12, that is, in the vicinity of the upper end in the figure.
The second retroreflective portion according to the present invention is provided at a position that does not block L _2.
32 is additionally provided.

The first retroreflective part 31 in this case is
For example, the retroreflective member 21 described with reference to FIG. 7 has a cylindrical shape having a diameter substantially equal to the diameter of the parallel light flux L ′ emitted from the light source section 11, and for example, the reflector 11 constituting the light source section 11.
It is fixed by means such as being attached to the inner surface of the cylindrical member 31a attached to the outer surface portion or the like of 1.

The second retroreflective portion 32 is composed of the plate-shaped retroreflective member 21 having a size that can cover at least the shaded area E described in FIG. 6, and is, for example, a dichroic mirror 121. _-1 is fixed to the attachment fixing plate 32a fixed to the upper end side portion of the frame (not shown) by means such as adhesion.

In this case, the light emitted from the light source 112 is directed to the inner reflector 111 as described above.
111 forms a parallel light flux L ', but as shown in (1-2), the light L ₃ traveling toward the first retroreflector 31 and the second retroreflector
Since the light L ₄ traveling toward 32 goes backward in the respective retroreflecting portions 31, 32 and returns to the light source 112, it can be directly incident on the optical system 12 as the parallel light flux L ′.

Therefore, almost all of the light emitted from the light source 112 can be effectively used, and the image on the screen can be brightened. The first and second retroreflective parts 31,
In the projection type optical device 3 having the 32 mounted thereon, the beads themselves constituting each retroreflective portion serve as a light reflector, so that it may take a lot of cost and man-hours to form and mount them like the mirror 15 in FIG. In addition, since there is no need for a space near the light source section unlike the mirror 15, there is an advantage that the size of the projection type optical device can be reduced.

Both the first retroreflective portion 31 and the second retroreflective portion 32 described above are the retroreflective members described in FIG.
Even if it is formed of 25, the same effect can be obtained. FIG. 2 in which only the main part of the projection type optical device according to the present invention is extracted.
Does not block the light ray L ₂ near the light source side end of the dichroic mirror 121 _-1 , that is, near the lower end side in the figure, only the first retroreflective section 31 among the retroreflective sections 31 and 32 in FIG. Flat ring-shaped third retroreflective portion 41 disposed at a position
The projection optical device 4 is configured by replacing

In this case, the third retroreflective portion 41 is
For example, the dichroic mirror 121 _-1 can be fixed to the attachment fixing plate 41a fixed to the lower end side portion of the frame (not shown) by adhesion or the like.

In the projection optical device 4 equipped with the third and second retroreflective parts 41 and 32, the lights L ₅ and L ₄ traveling toward the retroreflective parts 41 and 32 are both retroreflective parts. The optical system 12 returns to the light source 112 by going backwards at 41 and 32 as a parallel light flux L '.
Since it is incident on the screen, the screen image can be brightened as in the projection type optical device 3 of FIG. 1, and the retroreflective parts 41 and 32 can be used as the flat retroreflective member 2 respectively. There is a merit that easy mounting can be realized.

In the projection type optical device 5 shown in FIG. 3 in which only the main part relating to the present invention is extracted similarly to FIG. 2, only the third retroreflective part 41 in the projection type optical device 4 corresponds to the mirror 15 in FIG. It is replaced with a fourth retroreflective portion 51 formed in a truncated cone shape having a "H" -shaped cross section disposed at the position.

In this case, the fourth retroreflective portion 51 is
A dichroic mirror similar to the third retroreflective unit 41 described above.
121 _-1 Attachment fixing plate 51 fixed to a frame (not shown)
Although it can be fixed to a, it is not necessary to make the axis alignment and the inclination with respect to the optical axis as strict as in the conventional mirror 15, so that there is an advantage that it can be easily formed only by bending the plate-shaped retroreflective member 21, for example.

In the projection type optical device 5 equipped with the fourth retroreflective portion 51 and the second retroreflective portion 32, the light L ₆ and L ₄ traveling toward the respective retroreflective portions 51 and 32 are both of the respective light. Retroreflective part 51,3
Since it goes back to 2 and returns to the light source 112, the screen image can be brightened as in the projection type optical device 3 of FIG. 1, and each retroreflective portion can be configured only by simple processing of the retroreflective member 2. There is an advantage that the price of the device can be reduced together with the ease of mounting the retroreflective portions.

[0037]

As described above, according to the present invention, the optical device is constructed so that the light radially emitted from the light source is converted into a parallel light flux without waste, and the projection light on the screen becomes bright. It is possible to provide a projection-type optical device that can be improved.

In the description of the present invention, the case where the projection type optical device is a projector in the field of liquid crystal displays is taken as an example, but an optical device provided with a light source section for collimating light emitted from a light source through a reflector. Obviously, it can be applied to any device.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a projection type optical device according to the present invention.

FIG. 2 is a diagram illustrating a main part of a second configuration example as a projection type optical device.

FIG. 3 is a diagram for explaining a third configuration example of a projection type optical device as a main part.

FIG. 4 is a diagram schematically showing a configuration of a projection type optical device.

FIG. 5 is a diagram illustrating a configuration example of a conventional projection type optical device.

FIG. 6 is a diagram illustrating a problem.

FIG. 7 is a diagram illustrating an example of a retroreflective member.

FIG. 8 is a diagram showing another configuration example as a retroreflective member.

[Explanation of symbols]

3,4,5 Projection type optical device 11 Light source section 12 Optical system 21 Retroreflective member 31 First retroreflective section 31a Cylindrical member 32 Second retroreflective section 32a Attachment fixing plate 41 Third retroreflective section 41a Attachment Fixing plate 51 Fourth retroreflective part 51a Attachment fixing plate 111 Reflector 112 Light source 121 _1-1 Dichroic mirror (optical element)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiro Suzuki 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Tetsuya Hamada 1015, Kamedotachu, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited ( 72) Inventor Keiji Hayashi 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (4)

[Claims] 1. A light source section consisting of a light source and a reflector for emitting a parallel light flux, an optical system for processing the parallel light flux into a desired parallel light flux, and a projection lens for projecting the parallel light flux from the optical system onto a screen. And a retro-reflecting means comprising a retro-reflecting member for retrogressing a region of the light radially emitted from the light source, which is not converted into a parallel light flux in the light source section, to the light source. A projection type optical device characterized by: 2. The retroreflecting means according to claim 1, wherein the light flux on the light source section side of the optical system is emitted from a reflector end side of the light source section with a diameter formed by a parallel light flux peripheral surface between the light source section and the optical system. A first retroreflective portion having a length up to an unobstructed position and mounted in a parallel light flux region between the light source section and the optical system; and an optical element facing the light source section of the optical system. With a size that can cover the direct irradiation area from the light source on the surface orthogonal to the parallel light flux from the light source section including the vicinity of the rear surface side end portion, the optical axis is aligned with the rear surface side end portion of the optical element. A projection-type optical device comprising: a mounted plate-shaped second retroreflective portion; 3. The retroreflective device according to claim 1, wherein the retroreflecting means includes a portion of the optical element facing the light source portion of the optical system, the end portion of the optical element facing the light source side, and a plane orthogonal to the parallel light flux from the light source portion. A flat donut-shaped third retroreflective portion having a size capable of covering a region of the direct irradiation region excluding the parallel light flux region and being mounted in the vicinity of a light source side end of the optical element with its optical axis aligned; A second retroreflective portion according to claim 2, and a projection type optical device. 4. The retroreflective means according to claim 1, wherein the parallel light flux area of a surface orthogonal to the parallel light flux from the light source section near the light source side end of the optical element facing the light source section of the optical system is narrowed. A projection type optical device comprising: a fourth retroreflective portion having a truncated cone shape having a "H" cross section on the radial side; and a second retroreflective portion according to claim 2.