Projection apparatus

A projection apparatus including an illumination system, a light valve, a first optical element, a first projection lens, and a second projection lens is provided. The illumination system is suitable to provide an illumination beam, and the light valve is disposed on a transmission path of the illumination beam. The light valve is suitable to convert the illumination beam into an image beam. The first optical element is disposed on a transmission path of the image beam. A portion of the image beam is reflected by the first optical element, and a remaining portion of the image beam passes through the first optical element. The first projection lens is disposed on a transmission path of the image beam passing through the first optical element, and the second projection lens is disposed on a transmission path of the image beam reflected by the first optical element.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 95134929, filed Sep. 21, 2006. All disclosure of the Taiwan application is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display apparatus, and more particularly, to a projection apparatus.

2. Description of Related Art

A conventional projection apparatus100can only project one image in one direction for viewing. However, in a large conference venue (as shown inFIG. 1), a large number of people attends the conference, and people far away from the screen50(e.g., people in the region A1) cannot clearly see an image projected by the projection apparatus100onto the screen50. Moreover, in a meeting room (as shown inFIG. 2), not only those far away from the screen50cannot clearly see the image projected by the projection apparatus100onto the screen50, but also some people must view the screen50at certain angles, thus feel uncomfortable when viewing.

In order to solve the above problems, conventionally, more than two projection apparatuses100are arranged in the large conference venue (as shown in FIGS.3and4). However, this arrangement would increase cost.

Referring toFIG. 5, in consideration of the cost, a beam splitter60is additionally disposed between the projection apparatus100and the screen50, so that a portion of an image beam102projected by the projection apparatus100pass through the beam splitter60and is projected onto the screen50, and the other portion of the image beam102is reflected onto another screen50′. However, as the image beam102outside the projection apparatus100has a large divergence angle, a large-sized beam splitter60is required, and also a supporting structure for the beam splitter60is added, thus occupying a considerable space. Moreover, under this architecture, the distance between the screen50and the screen50′ is limited, which causes inconvenience in use. And, the images on the two screens cannot be focused simultaneously, resulting in a blurred image on one of the screens.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a projection apparatus having a bi-directional projection function.

In order to achieve the above and other objectives, a projection apparatus including an illumination system, a light valve, a first optical element, a first projection lens, and a second projection lens is provided. The illumination system is suitable to provide an illumination beam, and the light valve is disposed on a transmission path of the illumination beam. Also, the light valve is suitable to convert the illumination beam into an image beam. The first optical element is disposed on a transmission path of the image beam. A portion of the image beam is reflected by the first optical element, and a remaining portion of the image beam passes through the first optical element. The first projection lens is disposed on a transmission path of the image beam passing through the first optical element, and the second projection lens is disposed on a transmission path of the image beam reflected by the first optical element.

A projection apparatus including an illumination system, a light valve, a first optical element, a first projection lens, and a second projection lens is further provided. The illumination system is suitable to provide an illumination beam, and the light valve is disposed on a transmission path of the illumination beam. Also, the light valve is suitable to convert the illumination beam into an image beam. The first optical element is disposed on a transmission path of the image beam, and the first optical element comprises a body and a driving device connected to the body. The body has a reflecting portion, a light splitting portion, and a light-transmission portion, and the driving device is suitable to drive the body to intersect one of the reflecting portion, the light splitting portion, and the light-transmission portion on the transmission path of the image beam. When the reflecting portion intersects the transmission path of the image beam, the image beam is reflected by the reflecting portion. When the light splitting portion intersects the transmission path of the image beam, a portion of the image beam is reflected by the light splitting portion and the other portion of the image beam passes through the light splitting portion. When the light-transmission portion intersects the transmission path of the image beam, the image beam passes through the light-transmission portion. Furthermore, the first projection lens is disposed on a transmission path of the image beam passing through the first optical element, and the second projection lens is disposed on a transmission path of the image beam reflected by the first optical element.

In the present invention, as a portion of the image beam can pass through the first optical element and is then transmitted to the first projection lens, and the other portion of the image beam is reflected by the first optical element to the second projection lens, the projection apparatus of the present invention has a bi-directional projection function.

DESCRIPTION OF EMBODIMENTS

FIG. 6is a schematic view of a projection apparatus according to an embodiment of the present invention. Referring toFIG. 6, a projection apparatus200in this embodiment includes an illumination system210, a light valve220, a first optical element230, a first projection lens240, and a second projection lens250. The illumination system210is suitable to provide an illumination beam212, and the light vale220is disposed on a transmission path of the illumination beam212. Also, the light valve220is suitable to convert the illumination beam212into an image beam213. The first optical element230is disposed on a transmission path of the image beam213. A portion of the image beam213is reflected by the first optical element230, and a remaining portion of the image beam213passes through the first optical element230. The first projection lens240is disposed on a transmission path of the image beam213passing through the first optical element230, and the second projection lens250is disposed on a transmission path of the image beam213reflected by the first optical element230.

In this embodiment, the illumination system210includes a light source (not shown) for providing the illumination beam212. The illumination beam212provided by the light source is projected onto the light valve220after passing through optical elements (such as a lens and an integrated column) inside the illumination system210. The light valve220can be a transmissive light valve or a reflective light valve, wherein the transmissive light valve can be a transmissive liquid crystal panel and the reflective light valve can be a digital micro-mirror device (DMD) or a liquid crystal on silicon panel (LCOS panel). The reflective light valve is taken as an example as shown inFIG. 6. After converting the illumination beam212into the image beam213, the light valve220reflects the image beam213to the first optical element230. The first optical element230is, for example, a beam splitter, which can reflect a portion of the beam and allow the other portion of the beam passing therethrough. In particular, the first optical element230is a beam splitter with a transmittance of 50% and a reflectance of 50%. Thus, when the image beam213is transmitted to the first optical element230, a portion of the image beam213passes through the first optical element230and is then transmitted to the first projection lens240, while the other portion of the image beam213is reflected by the first optical element230to the second projection lens250. Moreover, the first projection lens240and the second projection lens250can project the image beam213onto the screen50and the screen50′ respectively, so as to respectively form an image on the screen50and the screen50′.

Because the image beam213can be projected onto different screens via the first projection lens240and the second projection lens250, the projection apparatus200in this embodiment has a bi-directional projection function, thereby saving the cost of adding additional projection apparatuses. Moreover, the first projection lens240and the second projection lens250can be focused respectively, so the images on the screen50and the screen50′ are clear. Furthermore, the distance between the screen50and the screen50′ is not limited herein, so it is convenient in use.

In this embodiment, the first projection lens240and the second projection lens250with different focal length can be used, so as to provide various throw ratios of the projection apparatus200. In this manner, a desired picture size can be obtained with the same projection distance. Additionally, as the first optical element230is disposed within the projection apparatus200, the first optical element230does not need to have a large size. Compared with the architecture of the projection apparatus100ofFIG. 5with the beam splitter60, the architecture of the projection apparatus200in this embodiment is obviously smaller.

It should be noted that although in the projection apparatus200described above, the first projection lens240and the second projection lens250project face opposite directions, a reflection element can be additionally arranged within the projection apparatus according to the present invention, so as to change arrangement projection direction and position of the first projection lens240and/or the second projection lens250, and the details will be illustrated in the following embodiments.

FIGS. 7A and 7Bare schematic views of projection apparatuses according to another two embodiments of the present invention. Referring toFIGS. 7A and 7B, compared with the projection apparatus200, projection apparatuses200a,200brespectively further include a reflection element260disposed on the transmission path of the image beam213reflected by the first optical element230so as to reflect the image beam213transmitted thereon to the second projection lens250. In other words, by arranging the reflection element260and adjusting arrangement angles of the reflection element260and the first optical element230, the second projection lens250can be arranged at a desired position to meet the requirement for the projection direction of the second projection lens250.

It should be noted that the number of the reflection elements260is not limited in this embodiment, i.e., a plurality of reflection elements260can be additionally arranged within the projection apparatus to achieve the purpose of arranging the second projection lens250at a desired position. Moreover, the reflection element260can also be disposed on the transmission path of the image beam213passing through the first optical element230, so as to reflect the image beam213transmitted thereon to the first projection lens240. In this manner, the first projection lens240can be arranged at a desired position, thereby meeting the requirements for the projection direction of the first projection lens240.

FIG. 8is a schematic view of a projection apparatus according to still another embodiment of the present invention. Referring toFIG. 8, compared with the projection apparatus200ofFIG. 6, a projection apparatus200cin this embodiment further includes a second optical element270and a third projection lens280. The second optical element270is disposed on the transmission path of the image beam213reflected by the first optical element230. A portion of the image beam213is reflected by the second optical element270to transmit to the third projection lens280, and a remaining portion of the image beam213passes through the second optical element270to transmit to the second projection lens250.

The first optical element230and the second optical element270are both, for example, beam splitters. In order to achieve the same brightness of the images projected by the first, second, and third projection lenses240,250, and280, the first optical element230can be a beam splitter with a transmittance of 33% and a reflectance of 67%, and the second optical element270can be a beam splitter with a transmittance of 50% and a reflectance of 50%.

In this embodiment, besides the first projection lens240and the second projection lens250used to project the image beam213onto the screen50and the screen50′ respectively, the third projection lens280can also be used to project the image beam213onto a screen50″, and thus the projection apparatus200chas a three-directional projection function. Furthermore, in this embodiment, more projection lenses and optical elements capable of reflecting a portion of the beam and allowing the other portion of the beam passing there-through can be additionally arranged within the projection apparatus200c, so as to achieve the purpose of multi-directional projection. Additionally, the second optical element270can also be disposed on the transmission path of the image beam213passing through the first optical element230. In this case, a portion of the image beam213is reflected by the second optical element270to transmit to the third projection lens280, and a remaining portion of the image beam213passes through the second optical element270to transmit to the first projection lens240. Those of ordinary skill in the art can easily deduce from the above description, and the details will not be repeated.

FIG. 9Ais a schematic view of a projection apparatus according to yet another embodiment of the present invention, andFIG. 9Bis a schematic view of the first optical element inFIG. 9A. Referring toFIGS. 9A and 9B, a projection apparatus200din this embodiment is similar to the projection apparatus200ofFIG. 6, with a difference in the first optical element. In particular, a first optical element230aof the projection apparatus200dincludes a body and a driving device connected to the body (not shown). The body has a reflecting portion232, a light splitting portion234, and a light-transmission portion236, and the driving device is suitable to drive the body to intersect one of the reflecting portion232, the light splitting portion234, and the light-transmission portion236on the transmission path of the image beam213. The driving device may be a moving element (not shown) so as to drive the body to move relative to the light valve220. Furthermore, the light-transmission portion236is, for example, a transparent substrate, and the transparent substrate can be coated with an anti-reflection coating layer so as to avoid light reflection. The reflecting portion232is, for example, a reflection mirror. The light splitting portion234is, for example, a beam splitter. Moreover, the first projection lens240is disposed on the transmission path of the image beam213passing through the first optical element230a, and the second projection lens250is disposed on the transmission path of the image beam213reflected by the first optical element230a.

In this embodiment, the projection direction of the projection apparatus200dcan be adjusted by moving the first optical element230a. In particular, when the reflecting portion232is intersected on the transmission path of the image beam213, the image beam213is reflected by the reflecting portion232to the second projection lens250, and at this time, the image beam213only can be projected onto the screen50′ via the second projection lens250. If the light splitting portion234is intersected on the transmission path of the image beam213, a portion of the image beam213is reflected by the light splitting portion234to the second projection lens250, and the other portion of the image beam213passes through the light splitting portion234and is then transmitted to the first projection lens240, and at this time, the image beam213can be projected onto the screen50and the screen50′ simultaneously via the first projection lens240and the second projection lens250. When the light-transmission portion236intersects the transmission path of the image beam213, the image beam213can pass through the light-transmission portion236and is then transmitted to the first projection lens240, and at this time the image beam213only can be projected onto the screen50via the first projection lens240.

FIG. 10is a schematic view of another first optical element according to the present invention. Referring toFIG. 10, the first optical element230aof the projection apparatus200ddescribed above can also be replaced by a first optical element230bofFIG. 10. The first optical element230bincludes a body and a driving device connected to the body. The body includes a reflecting portion232, a light splitting portion234, and a light-transmission portion236. The driving device is, for example, a motor238which is suitable to drive the body to rotate therewith so as to intersect one of the reflecting portion232, the light splitting portion234, and the light-transmission portion236on the transmission path of the image beam213. By rotating the first optical element230b, it is possible to control the reflecting portion232, the light splitting portion234, or the light-transmission portion236intersecting the transmission path of the image beam, such that the projection direction of the projection apparatus200dcan be adjusted. The reflecting portion232is, for example, a reflection mirror, and the light splitting portion234is, for example, a beam splitter.

In view of the above, the projection apparatus of the present invention has at least one or more of the following advantages:

1. As an image beam can be projected onto different screens via a first projection lens and a second projection lens, the projection apparatus of the present invention has a bi-directional projection function.

2. The focuses of the first projection lens and the second projection lens can be adjusted respectively, and thus the images projected onto two screens can be adjusted to be clear.

3. By arranging the first projection lens and the second projection lens with different focal length, the projection apparatus can be provided with various throw ratios.

4. In the present invention, more number of projection lenses and optical elements capable of reflecting a portion of the beam and allowing the other portion of the beam to pass there-through can be additionally arranged within the projection apparatus, so as to achieve the purpose of multi-directional projection.

5. In an embodiment, as the first optical element is a moving element having a reflecting portion, a light splitting portion, and a light-transmission portion, the projection direction of the projection apparatus can be adjusted by moving the first optical element.