JP3094393B2 - Projection device for computer image display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector, and more particularly, to a projector for displaying computer images.

[0002]

2. Description of the Related Art Digital micro-mirror devices often generate images by reflection and are used as an image module of a reflection projection device for projecting an image. However, in such projectors the distance between the incident light and the reflected light is often small. In order to avoid undesired interference between the light beams, the projection device must be very large.

Referring to FIG. 1, a cross-sectional view of a prior art reflection projection apparatus 10 is shown. The reflection projection device 10 modulates the incident light beam 11 to generate a reflected light beam 13 including an image. The image module 12 includes a plurality of controllable reflecting surfaces (not shown). A total reflection prism 14 for preventing interference between reflected light beams 13 reflected from the optical device 16, an optical device 16 such as a dichroic mirror or a dichroic prism, a reflected light beam 13 including an image, and an output image are combined. And a projection lens 18 to be intense.

The projection apparatus 10 uses a total reflection prism 14 for preventing interference between the emitted light beam 11 and the reflected light beam 13 reflected from the image module 12. A long back focal length 19, ie a long distance between the image module 12 and the projection lens 18, is required. Therefore, the projection apparatus 10 has to be very large, and has a complicated structure that leads to an increase in manufacturing cost. Prism 14 is incident light 11
Although the ray trace between the light and the reflected light 13 is shortened, it also causes chromatic aberration in the reflected light, thereby deteriorating the image. The prism 14 also reflects unwanted deflected light onto the projection lens 18, which reduces image contrast. Finally, the assembly requirements for the total reflection prism 14 are strict, which increases the complexity of the structure and the manufacturing costs.

[0005]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a projection apparatus which solves the above-mentioned problems.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a light source for generating an incident light beam; a reflective image module comprising a plurality of controllable reflective surfaces for modulating the incident light and generating a reflected light beam containing an image; A first lens set for concentrating the incident light beam; a reflecting mirror for reflecting the incident light beam from the light source through the first lens set onto the image module; a light source and a reflection for shortening an optical path from the light source to the reflecting mirror A second lens set provided between the mirror and the mirror, wherein an optical path of the incident light reflected from the image module is a surface formed by an optical path of the incident light from the light source to the reflector and from the reflector to the image module. At a single point.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 2, a projection device 20 according to the present invention is schematically shown. The projection device 20 includes a light source 21,
Third lens set 26, rotatable color wheel 40, second lens set 28, reflector 30, first lens set 32, reflection image module 34, projection module 3
6. A control module 38 for outputting an image control signal to the image module 34.

The light source 21 includes a light valve 22 and a reflecting mirror 24, and generates a first incident light beam 46. The third lens set includes a color filter 4 that is rotatable with the light source 21 to focus the first incident light beam 46 on the color filter.
0 is provided. The rotatable color wheel 40 is red,
The first incident light beam 46 is rotated to be colored in order to sequentially generate green and blue. The filtered first incident light beam 46 then passes through a second lens set 28, which
The path of the incident ray 46 to zero is shortened, where it is reflected to the first lens set 32 which focuses this second incident ray 48 on the image module 34. The image module 34 is a reflective liquid crystal display or digital micro-mirror device, comprising a plurality of micro-mirrors arranged in a controllable matrix configuration. Based on the control signal received from the control module 38, the image module 34 causes the second incident beam 4 to generate a reflected beam 50 containing the image passing through the output projection module 36 when it is focused.
Modulate 8.

The rotatable color wheel 40 comprises a plurality of transparent red, green and blue color filters 48, each of which is provided at a position 42 on the circular panel 41 at an equal distance from the center thereof. The rotatable color wheel rotates at a constant speed along its axis 45 to route the first incident light beam 46 sequentially into red, green, and blue light. The filtered reflected light beam 50 is output as if the image synthesized with the user's vision was perceived.

The first and second lens sets 32, 28 of the projection device 20 have positive diopters that substantially reduce the entire optical path length of the incident light beam 46 from the incident light source 21 to the image module 34. After processing by the color filters, the incident light beam 46 is best focused on the image module 34 with maximum light use efficiency such that its focused spot size is just enough to cover the total reflection surface of the image module 34. . The reflector 30 and the image module 34 are arranged at an angle such that the intersection of the incident ray 48, the reflected ray 50 and the incident ray 46 in three-dimensional space is prevented. This also allows a significant reduction in the size of the projection device 20.

Referring to FIG. 3, there is shown a ray trace of rays 46, 48 and 50 in a three-dimensional space formed by x, y and z axes. The first incident light beam 46 is generated by the light source 21 and passes through the optical axes of the third and second lens sets 26, 28 and reaches the reflector 30, where it becomes the second incident light beam 48. The light is reflected so as to pass through one lens set 32. The angle between the optical axis and the x axis is between 0 and 1
An angle between 5 degrees. The second incident ray 48 is reflected by the image module 34 in the X, Y plane to form a reflected ray 50, which is then emitted through the projection module 36. FIG. 3 also shows that the normal 51 (the positive direction of the z-axis) of the reflective surface of the image module 34 crosses the surface formed by the rays 46 and 48 at zero. The y-axis position of the image module 34 is higher than the y-axis position of the reflector 30 and the light source 21 and lower than that of the projection module 36.

The angle α between the reflected ray 50 and the normal 51 of the image module 34 (positive direction of the z-axis) is between 2 and 18 °, and the angle α along the optical axis of the first lens set. The angle θ between the two incident rays 48 and the normal 51 is between 21 and 35
゜, and XY of the optical axis of the first lens set 32
The angle φ between the plane projection line 53 and the x-axis is −48 to −68 degrees. The lens sets 26, 28, 32, together with the reflector 30, form curved optical paths 46, 48 through the optical axis and its course between each lens set. With this 3D design, the volume of the projection device 20 is dramatically reduced.

In the projection device 20, a first lens set 32
Is the convergence of the aspherical convex surface or the aspherical biconvex surface
ive) lens, the conic of the focusing lens
c) is between 1.2 and -0.45. Also occupied by the incident light beam 48 to reduce the height of the projection device 20 while maintaining light efficiency and to prevent interference of the reflected light beam 50 generated by the image module 34 having the first lens set 32. Areas that are not removed are removed to prevent shadowing of the reflected ray 50. Further reduction in the size of projection device 20 is achieved by making the angle between rays 48 and 50 as small as possible.

In the projection device 20, a second lens set 28
Usually consists of two converging lenses. Image module 34
Varies depending on the degree of improvement in the resolution. The size of the image module 34 is two lens sets 2
It is minimized while maintaining high light utilization efficiency when 8, 32 meets the following conditions:

[0015]

(Equation 2)

Where F _A is the focal length of the first lens set, F _B is the focal length of the second lens set, and F _AB is the combined focal length of the two lens sets. Referring to FIG. 4, this is a diagram showing the relative positions of the first and second lens sets 32,28. The second lens set 28 includes the first lens 27 and the second lens 2.
9 A first lens 27, a second lens 29,
The first lens set 32 is an aspheric lens and includes a front side and a rear side, respectively. The incident light beam 46 passes through the color filter 43 of the rotatable color wheel 40, and a front side 52 of the first lens 27 and a rear side 54 of the first lens 27.
And the front side 56 of the second lens 29 and the second lens 29
And the front side 60 of the first lens set 32
And the rear side 62 of the first lens set 32,
The incident light beam 48 passing over the image module 34 is formed.

Referring to FIGS. 5 and 6, the refractive index, the front and rear radii of curvature, the first lens 27 and the second lens 2 are shown.
A change in the design of the relative position between the first lens set 9 and the first lens set 32 is shown. 5 to 8 show four preferred embodiments. The thickness (d2) of the first lens 27 is 6 mm
The distance (d3) from the first lens 27 to the second lens 29 is 1 mm, the thickness (d4) of the second lens 29 is 6 mm, and the distance (d3) from the second lens 29 is The distance (d5) to the lens set 32 is 70 mm, and the thickness (d6) of the first lens set 32 is 17 mm
It is. The refractive index of each lens was calculated to correspond to a wavelength of 0.587 μm. The cone of the first lens 3 in FIG.
1.00, and is -0.97 in FIGS.
Other relevant optical data is shown in FIGS.

In the present invention, the lens sets 28, 32 and the reflector 30 of the projection device 20 are arranged to shorten the optical path and prevent the intersection of light rays, thereby reducing the overall size of the projection device. Since the projection device 20 does not include a prism, chromatic aberration and light deflection do not occur. This facilitates installation and reduces manufacturing costs.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a prior art reflection projection device.

FIG. 2 is a schematic diagram of a projection device according to the present invention.

FIG. 3 is a ray trace diagram of the light beam shown in FIG. 2;

FIG. 4 is a layout diagram showing relative positions of first and second lens sets shown in FIG. 2;

FIG. 5 is a list of relevant optical data of the first preferred embodiment.

FIG. 6 is a list of relevant optical data of the second preferred embodiment.

FIG. 7 is a list of relevant optical data of the third preferred embodiment.

FIG. 8 is a list of relevant optical data of the fourth preferred embodiment.

[Explanation of symbols]

 Reference Signs List 10 Projection device 11 Incident light beam 13 Reflected light beam 12 Image module 14 Prism 16 Optical device 18 Projection lens 19 Back focal length 20 Projection device 20 21 Light source 26 Third lens set 27 First lens 29 Second lens 28 Second Lens set 30 reflector 32 first lens set 34 reflection image module 36 projection module 38 control module 38 40 color wheel 46, 48, 50 incident light beam 41 circular panel 42 position 45 axis 51 normal 54, 58, 62 rear side 56, 60, 64 Front side d2 Thickness of first lens d3 Distance from first lens to second lens d4 Thickness of second lens d5 Distance from second lens to first lens set d6 First lens set thickness

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Cheng Xi-Ping Taiwan Taipei Xian San-Shia Chun-Chong Road Section 2 Number 319 (56) References JP-A-8-304926 (JP, A) Kaihei 8-201755 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03B 21/00 G02B 13/16 H04N 5/74

Claims (23)

(57) [Claims] A light source for generating incident light; a reflective image module comprising a plurality of controllable reflective surfaces for modulating the incident light and generating a reflected light including an image; a first lens for concentrating the incident light. A reflector that reflects an incident light beam from the light source through the first lens set and onto the image module; and a second light source provided between the light source and the reflector to shorten an optical path from the light source to the reflector. A projection device, comprising two lens sets, wherein the optical path of the incident light beam reflected from the image module traverses the surface formed by the optical path of the incident light beam from the light source to the reflector and from the reflector to the image module at only one point. 2. The projection device according to claim 1, wherein the first lens set is an aspheric convex surface or an aspheric biconvex surface, and the conical lens has a cone between −1.2 and −0.45. . 3. The second lens set is formed by two converging lenses, and the first and second lens sets satisfy the following equation: Where F _A is the focal length of the first lens set, F _B
The projection device according to claim 1, wherein is the focal length of the second lens set, and F _AB is the combined focal length of the two lens sets. 4. The incident light beam generated by the light source is concentrated by the second lens set, and then the first lens set before it substantially reduces the overall length of the optical path from the light source to the image module. The projection device according to claim 1, which is sent to an image module. 5. The projection device according to claim 1, wherein the light source comprises a curved reflector for directing reflected light generated by the light source in one direction to form an incident light beam of the light source. 6. The projection device according to claim 1, wherein the light reflection angles of each reflection surface of the image module are separately controlled by the image module to generate a reflected light beam including an image. 7. The projection device according to claim 6, wherein the image module is a digital micro mirror device. 8. The projection device according to claim 1, wherein the image module is a reflective liquid crystal display. 9. The projection device according to claim 1, further comprising a rotatable color wheel provided between the light source and the second lens set to change a color of an incident light beam generated by the light source. 10. The projection of claim 9 wherein the color wheel comprises a circular panel having a plurality of peripherally provided transparent color filters that convert incident light into various colored light beams when the color wheel rotates. apparatus. 11. The projection device according to claim 10, wherein the color wheel comprises red, green, and blue color filters for converting incident light into red, green, and blue incident light. 12. The projection apparatus according to claim 11, wherein the red, green, and blue color filters are sequentially arranged so as to form red, green, and blue incident light rays. 13. The apparatus according to claim 1, further comprising a third lens set provided between the light source and a rotatable color wheel for focusing an incident light beam generated by the light source on a color filter.
Projection device as described. 14. The projection device according to claim 1, wherein the first and second lens sets have positive reflectivity. 15. The first lens set is an aspherical lens, the second lens set comprises a first lens and a second lens, and the first lens set and the first lens set of the second lens set. The second lens has a front side and a rear side, respectively, and the incident light emitted from the light source is sequentially the front side of the first lens, the rear side of the first lens, the front side of the second lens, and the second side. 15. The projection device according to claim 14, wherein the projection device passes through a rear side of the first lens set, a front side of the first lens set, and a rear side of the first lens set. 16. The relevant data of the first lens set, the second lens set and the first lens set of the second lens set are: Refractive index (at wavelength 0.587 μm) of the first lens =
1.74, refractive index (at 0.587 μm wavelength) of the second lens =
1.52, refractive index of the first lens set (at a wavelength of 0.587 μm) = 1.52, cone of the first lens set = −0.97, radius of curvature of the front side of the first lens = infinity Radius of curvature on the rear side of the first lens = 14 mm, radius of curvature on the front side of the second lens = infinity, radius of curvature on the rear side of the second lens = 16 mm, radius of curvature on the front side of the first lens set = −21 mm, radius of curvature behind the first lens set = infinity, thickness of the first lens = 6 mm, distance from the rear side of the first lens to the front side of the second lens = 1 mm, The projection device according to claim 15, wherein the thickness of the second lens is 6 mm, the distance from the rear side of the second lens to the front side of the first lens set is 70 mm, and the thickness of the first lens set is 17 mm. 17. The relevant data of the first lens set, the second lens set and the first lens set of the second lens set are: Refractive index (at wavelength 0.587 μm) of the first lens =
1.74, refractive index (at 0.587 μm wavelength) of the second lens =
1.74, refractive index of the first lens set (at a wavelength of 0.587 μm) = 1.52, cone of the first lens set = −1.00, radius of curvature of the front side of the first lens = 60 mm, Radius of curvature at the back of the first lens = 12 mm, radius of curvature at the front of the second lens = infinity, radius of curvature at the back of the second lens = 16 mm, radius of curvature at the front of the first lens set = -21 mm, radius of curvature behind the first lens set = infinity, thickness of the first lens = 6 mm, distance from the back of the first lens to the front of the second lens = 1 mm, the second The projection device according to claim 15, wherein the thickness of the first lens set is 6 mm, the distance from the rear side of the second lens to the front side of the first lens set is 70 mm, and the thickness of the first lens set is 17 mm. 18. The relevant data of the first lens, the second lens and the first lens set of the second lens set are: Refractive index (at wavelength 0.587 μm) of the first lens =
1.74, refractive index (at 0.587 μm wavelength) of the second lens =
1.52, refractive index of the first lens set (at a wavelength of 0.587 μm) = 1.52, cone of the first lens set = −0.97, radius of curvature of the front side of the first lens = infinity Radius of curvature on the rear side of the first lens = 15.5 mm, radius of curvature on the front side of the second lens = infinity, radius of curvature on the rear side of the second lens = 17 mm, front side of the first lens set Radius of curvature = -21 mm, radius of curvature behind the first lens set = infinity, thickness of the first lens = 6 mm, distance from the back of the first lens to the front of the second lens = 1 mm The thickness of the second lens = 6 mm, the distance from the rear side of the second lens to the front side of the first lens set = 70 mm, and the thickness of the first lens set = 17 mm. apparatus. 19. The relevant data of the first lens set, the second lens set and the first lens set of the second lens set are: Refractive index (at 0.587 μm wavelength) of the first lens =
1.74, refractive index (at 0.587 μm wavelength) of the second lens =
1.52, refractive index of the first lens set (at a wavelength of 0.587 μm) = 1.52, cone of the first lens set = −0.97, radius of curvature of the front side of the first lens = infinity Radius of curvature on the rear side of the first lens = 18.5 mm, radius of curvature on the front side of the second lens = infinity, radius of curvature on the rear side of the second lens = 17 mm, front side of the first lens set Radius of curvature = -21 mm, radius of curvature behind the first lens set = infinity, thickness of the first lens = 6 mm, distance from the back of the first lens to the front of the second lens = 1 mm The thickness of the second lens = 6 mm, the distance from the rear side of the second lens to the front side of the first lens set = 70 mm, and the thickness of the first lens set = 17 mm. apparatus. 20. The projection device according to claim 1, further comprising a projection module for projecting a light beam reflected by the image module on a screen. 21. The angle between the projection ray and the normal of the image module is between 2 and 18 °, and the angle between the optical axis of the first lens set and the normal of the image module is between 21 and Between 35 °, the line defined by projecting the optical axis of the first lens set onto the surface on which the image module is located, the normal of the plane formed by the projection rays and the normal of the image module. Angle between lines -48 to -68
21. The projection device according to claim 20, which is a degree. 22. An incident light beam generated by the light source is transmitted along a direction of an optical axis of the second lens set, and a normal and an image of a surface formed by the optical axis of the second lens set and the projection light beam. 2. The projection device according to claim 1, wherein the angle between the module and the normal is between 0 and 15 degrees. 23.A light source for generating incident light; Modulates the incident light to produce multiple reflected rays containing the image
A reflective imaging module comprising a controllable reflective surface; A first focusing module for focusing incident light rays; From the light source through the first lens set and onto the image module
A reflecting module for reflecting the incident light of Light source and reflection to shorten the optical path from the light source to the reflector
With a second shortening module between the mirror
And Is the path of the incident light reflected from the image module a light source?
To the reflection module and from the reflection module to the image module.
Point formed by the optical path of the incident light beam to the
Projection device that only traverses.