Projection system and its optical shutter

Abstract

An optical shutter for a projection system includes a shutter element and an actuator. The shutter element includes a light-shielding portion and a linkage portion. The light-shielding portion is disposed on the optical pathway of the projection system and is connected with the linkage portion. The light-shielding portion is bent toward the linkage portion and there is a pre-determined angle formed between the light-shielding portion and the linkage portion. The light-shielding portion faces the linkage portion with a predetermined angle. The actuator is coupled with the linkage portion to drive the shutter to swing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood from the subsequent detailed description and the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a schematic view of the conventional optical projection system;

FIG. 2 is a fragmentary sectional view of the conventional projection lens set and optical shutter;

FIG. 3 is a schematic view of an embodiment of the optical shutter according to the invention;

FIG. 4 is a side view of the optical shutter shown in FIG. 3;

FIG. 5 is a fragmentary sectional view of a optical shutter connected with the lens cylinder according to the invention; and

FIG. 6 is a schematic view of an embodiment of the projection system according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements.

As shown in FIG. 3, the optical shutter 20 according to the invention includes a shutter element 21 and an actuator 22. The optical shutter 20 can be used in a projection system.

As shown in FIGS. 3 and 4, the shutter element 21 includes a light-shielding portion 211 and a linkage portion 212 connected with each other. The light-shielding portion 211 faces the linkage portion 212 and bends toward the linkage portion 212 to form a predetermined outer angle θ (FIG. 4). In this embodiment, the outer angle is preferably smaller than or equal to 90 degrees. That is, the light-shielding portion 211 is not parallel to the linkage portion 212 and the angle between them is θ. Here the angle between the light-shielding portion 211 and a rotating axis X′ is equal to (90−θ), thus effectively reducing the rotational inertia. For example, when the outer angle is equal to 90, the light-shielding portion 211 is perpendicular to the linkage portion 212 and parallel to the rotating axis X′.

The light-shielding portion 211 is made of an opaque material, such as but not limited to plastic or metal. The light-shielding portion 211 has a notch 213. As shown in FIG. 3, the notch 213 is semi-circular, but not limited to this shape. The shape of the notch 213 can be modified according to the light-shielding efficiency of the projection system.

In this embodiment, the actuator 22 is a magnetic actuator. It includes at least a coil and a magnetic element (not shown). The magnetic element (e.g., a permanent magnet) is disposed corresponding to the coil. The coil is wound around the linkage portion 212. The coil is provided with an electrical current to produce a magnetic field. The interaction between the magnetic field and the magnetic element drives the shutter element 21 to swing. The relation between the coil and the magnetic element is not limited to the example disclosed herein. The magnetic element can be disposed on the linkage portion 212, and the coil is disposed corresponding to the magnetic element. Such a configuration also achieves the goal of driving the shutter element 21.

As shown in FIG. 5, the optical shutter 20 according to an embodiment of the invention is connected to a lens cylinder 30.

As shown in FIG. 5, the lens cylinder 30 includes a lens assembly 301 and a cylinder 302. The cylinder 302 is connected to one end of the lens assembly 301. Several lenses 31 are accommodated inside the lens cylinder 30.

The optical shutter 20 is connected to the lens cylinder 30 so that the shutter element 21 is on the optical pathway of the projection system. The action of the optical shutter 20 controls the optical fluxes in the projection system to efficiently improving the projected image and increasing its contrast.

As shown in FIG. 6, the optical shutter 20 is used in a projection system 4. Besides connecting with the lens cylinder 30 (indicated by “a” in FIG. 6), the optical shutter 20 in the projection system 4 can also be disposed at any arbitrary position on the optical pathway. For example, the optical shutter 20 can be disposed at a position after the beam passes through the color wheel 41 (“b” in FIG. 6), after the beam passes through the optical channel 42 (“c” in FIG. 6), or before or after the reflection by the image generator 44 (“d” and “e” in FIG. 6). All such positions are acceptable as long as the optical shutter 20 can result in differences in the optical fluxes and an increase in contrast of the image.

In summary, the optical shutter and projection system of the invention have the light-shielding portion of the shutter element bent by a predetermined angle toward the linkage portion. The distance between the optical shutter and the rotating axis of the shutter element is thus shorter. Therefore, for the same mass, the shutter element has a smaller rotational inertia and thus a faster response speed. Compared with the prior art, the shutter element of the invention is bent by a predetermined angle. When it is combined with the projection lens set, the entire size is smaller while. Therefore, the versatility in spatial configuration is increased to satisfy the trend of compactifying the projection system.

Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.

Claims

1. An optical shutter comprising: a shutter element having a light-shielding portion and a linkage portion connected to the light-shielding portion, wherein the light-shielding portion is bent toward the linkage portion by a predetermined angle; andan actuator coupled to the linkage portion for driving the light-shielding element.

2. The optical shutter as recited in claim 1, wherein the predetermined angle is the outer angle between the light-shielding portion and the linkage portion and is smaller than or equal to 90 degrees.

3. The optical shutter as recited in claim 1, wherein the actuator is a magnetic actuator having at least one coil and one magnetic element disposed corresponding to the coil.

4. The optical shutter as recited in claim 3, wherein the coil is wound around the linkage portion and the magnetic element is disposed at the linkage portion.

5. The optical shutter as recited in claim 1, wherein the light-shielding portion of the shutter element has a notch.

6. The optical shutter as recited in claim 5, wherein the notch is semi-circular.

7. A projection system comprising: a light source;a color wheel;an optical channel;a lens set;an image generator; anda projection lens set having an optical shutter, the optical shutter comprising: a shutter element having a light-shielding portion and a linkage portion connected with the light-shielding portion, wherein the light-shielding portion and is bent toward the linkage portion by a predetermined angle, andan actuator coupled to the linkage portion for driving the shutter element, wherein the light source produces a beam passing through the color wheel, the optical channel, and the lens set and entering the image generator, and the image generator projects the beam to form an image via the projection lens set.

8. The projection system as recited in claim 7, wherein the predetermined angle is the outer angle between the light-shielding portion and the linkage portion and is smaller than or equal to 90 degrees.

9. The projection system as recited in claim 7, wherein the actuator is a magnetic actuator having at least one coil and one magnetic element disposed corresponding to the coil.

10. The projection system as recited in claim 9, wherein the coil is wound around the linkage portion and the magnetic element is disposed at the linkage portion.

11. The projection system as recited in claim 7, wherein the light-shielding portion of the shutter element has a notch.

12. A projection system having a light source, a color wheel, an optical channel, at least one lens set, an image generator, and a projection lens set, wherein a beam generated by the light source passes through the color wheel, the optical channel and the lens set, is reflected by the image generator, and projects onto a screen via the projection lens set, and the optical flux of the beam emitted by the light source is controlled by a optical shutter, the optical shutter comprising: a shutter element having a light-shielding portion and a linkage portion connected with the light-shielding portion, wherein the light-shielding portion and is bent toward the linkage portion by a predetermined angle; andan actuator coupled to the linkage portion for driving the shutter element.

13. The projection system as recited in claim 12, wherein the optical shutter is disposed at a position after the beam passes through the color wheel.

14. The projection system as recited in claim 12, wherein the optical shutter is disposed at a position after the beam passes through the optical channel.

15. The projection system as recited in claim 12, wherein the optical shutter is disposed at a position before the beam passes through the image generator.

16. The projection system as recited in claim 12, wherein the optical shutter is disposed at a position after the beam passes through the image generator.

17. The projection system as recited in claim 12, wherein the predetermined angle is the outer angle between the light-shielding portion and the linkage portion and is smaller than or equal to 90 degrees.

18. The projection system as recited in claim 12, wherein the actuator is a magnetic actuator having at least one coil and one magnetic element disposed corresponding to the coil.

19. The projection system as recited in claim 12, wherein the coil is wound around the linkage portion and the magnetic element is disposed at the linkage portion.

20. The projection system as recited in claim 12, wherein the light-shielding portion of the shutter element has a notch.