Illumination system and projection apparatus

An illumination system includes a chip package, a first dichroic film, a second dichroic film, and a third dichroic film. The first dichroic film, the second dichroic film, and the third dichroic film are not parallel to each other and do not cross each other. The chip package includes a first light-emitting chip capable of emitting a first light beam, a second light-emitting chip capable of emitting a second light beam, and a third light-emitting chip capable of emitting a third light beam. The first light-emitting chip, the second light-emitting chip, and the third light-emitting chip are arranged in a row. The first dichroic film reflects the first light beam and transmitting the second light beam, the second dichroic film reflects the second light beam, the first dichroic film and the second dichroic film transmit the third light beam, and the third dichroic film reflects the third light beam.

BACKGROUND OF THE INVENTION

a. Field of the Invention

The invention relates to an illumination system and a projection apparatus having the illumination system.

b. Description of the Related Art

Currently, in a projection apparatus an ultra high pressure lamp capable of emitting white light may cooperate with a color wheel to produce red light, green light, and blue light in succession and to display color images as a result. Further, in the recent trend, red light emitting diodes, green light emitting diodes, and blue light emitting diodes are used as a light source for a projection apparatus.

Referring toFIG. 6, in a projection apparatus100where a red light emitting diode, a blue light emitting diode, and a green light emitting diode are used as a light source, an X-mirror102is commonly used to combine different color beams. The X-mirror102includes, for instance, a red dichroic mirror102aand a blue dichroic mirror102bcross to each other. A red light beam emitted from a red LED104R is reflected by the red dichroic mirror102a, a blue light beam emitted from a blue LED104B is reflected by the blue dichroic mirror102b, and a green light beam emitted from a green LED104G passes through the red dichroic mirror102aand the blue dichroic mirror102b. Hence, the X-mirror is allowed to guide the red light beam, the green light beam, and the blue light beam coming from different directions to propagate in an identical direction, and then these light beams are homogenized by a fly-eye lens106. Thereafter, the red light beam, the green light beam, and the blue light beam are reflected by a reflective mirror108and modulated by a digital micro-mirror device110to form a colored image beam. Finally, the colored image beam enters a projection lens112. However, in the X-mirror102, an adhesive region (i.e. overlapped region) between the red dichroic mirror102aand the blue dichroic mirror102bfails to deflect the red light beam, the green light beam, and the blue light beam to result in the loss of light. Besides, an area of the adhesive region compared with a cross-sectional area of a light beam emitted from a light-emitting diode becomes larger when the light-emitting diode instead of an ultra high pressure lamp is used. This may result in higher loss of light. Further, since the red light beam, the green light beam, and the blue light beam are incident to the X-mirror102from three different directions, the space-efficiency of components in a projection apparatus is poor and results in a bulky projection apparatus.

Further, as shown inFIG. 7, U.S. Pat. No. 7,201,498 discloses a light-mixing system where light beams emitted from LEDs124B,124G, and124R are reflected by three dichroic mirrors that are not parallel to each other and then are guided into an objective126. However, such design merely provides the function of combining different color beams but fails to disclose how to improve light-utilization efficiency and reduce occupied space of a projection apparatus. Similarly, the design of three dichroic mirrors not parallel to each other is also disclosed in U.S. Pat. No. 6,910,777 and U.S. Pat. No. 6,987,546. However, these designs similarly do not disclose how to improve light-utilization efficiency and space-utilization efficiency.

BRIEF SUMMARY OF THE INVENTION

The invention provides an illumination system with good light-utilization efficiency and space-utilization efficiency, and a projection apparatus including the illumination system.

Other advantages and objects of the invention may be further comprehended through the technical features disclosed in the invention.

In order to achieve one or part of or all the objectives or other objectives, in an embodiment of the invention, an illumination system is provided. The illumination system includes a chip package, a first dichroic film, a second dichroic film, and a third dichroic film. The chip package includes a first light-emitting chip capable of emitting a first light beam, a second light-emitting chip capable of emitting a second light beam, and a third light-emitting chip capable of emitting a third light beam. The first light-emitting chip, the second light-emitting chip, and the third light-emitting chip are arranged in a row, and the first light beam, the second light beam, and the third light beam have mutually different colors. The first dichroic film is disposed in the light paths of the first light beam, the second light beam, and the third light beam. The second dichroic film is disposed in the light paths of the second light beam and the third light beam. The third dichroic film is disposed in the light path of the third light beam. The first dichroic film, the second dichroic film, and the third dichroic film are not parallel to each other and do not cross each other. The first dichroic film, the second dichroic film, and the third dichroic film are numbered for the proximity to the chip package, and the first dichroic film is capable of reflecting the first light beam and transmitting the second light beam, the second dichroic film is capable of reflecting the second light beam, the first dichroic film and the second dichroic film are capable of transmitting the third light beam, and the third dichroic film is capable of reflecting the third light beam. The first light beam, the second light beam, and the third light beam form an illumination light beam as the first light beam, the second light beam, and the third light beam respectively leaving the first dichroic film, the second dichroic film, and the third dichroic film.

In one embodiment, the illumination system further includes a light-homogenizing element disposed in the light path of the illumination light beam and the chip package further includes a lens covering the first light-emitting chip, the second light-emitting chip, and the third light-emitting chip.

In one embodiment, the second light-emitting chip is disposed between the first light-emitting chip and the third light-emitting chip, and the sizes of the first light-emitting chip and the third light-emitting chip are both smaller than the size of the second light-emitting chip.

In another embodiment of the invention, a projection apparatus is provided. The projection apparatus includes an illumination system, a light valve, and a projection lens. The illumination system includes a chip package, a first dichroic film, a second dichroic film, and a third dichroic film. The chip package includes a first light-emitting chip capable of emitting a first light beam, a second light-emitting chip capable of emitting a second light beam, and a third light-emitting chip capable of emitting a third light beam. The first light-emitting chip, the second light-emitting chip, and the third light-emitting chip are arranged in a row, and the first light beam, the second light beam, and the third light beam have mutually different colors. The first dichroic film is disposed in the light paths of the first light beam, the second light beam, and the third light beam. The second dichroic film is disposed in the light paths of the second light beam and the third light beam. The third dichroic film is disposed in the light path of the third light beam. The first dichroic film, the second dichroic film, and the third dichroic film are not parallel to each other and do not cross each other. The first dichroic film, the second dichroic film, and the third dichroic film are numbered for the proximity to the chip package, and the first dichroic film is capable of reflecting the first light beam and transmitting the second light beam, the second dichroic film is capable of reflecting the second light beam, the first dichroic film and the second dichroic film are capable of transmitting the third light beam, and the third dichroic film is capable of reflecting the third light beam. The first light beam, the second light beam, and the third light beam form an illumination light beam as the first light beam, the second light beam, and the third light beam respectively leaving the first dichroic film, the second dichroic film, and the third dichroic film. The light valve is disposed in the light path of the illumination light beam for transforming the illumination light beam into an image beam. The projection lens is disposed in the light path of the image beam.

In one embodiment, the projection apparatus further includes a total-internal-reflection prism disposed in the light paths of the illumination light beam and the image beam and between the light valve and the projection lens.

In one embodiment, the projection apparatus further includes a reflective mirror disposed in the light path of the illumination light beam and between the illumination system and the light valve.

In one embodiment, the projection apparatus further includes a light-homogenizing element disposed in the light path of the illumination light beam and between the first dichroic film and the light valve, the light-homogenizing element is a fly-eye lens that has a plurality of lens elements arranged in an array, and each of the lens elements has a shape complementary to the shape of a light spot deformed as a result of oblique incidence.

In one embodiment, the illumination system further includes a condenser lens disposed in the light path of the illumination light beam and between the light-homogenizing element and the light valve, and a central axis of the condenser lens is away from an optical axis of the projection apparatus.

In another embodiment of the invention, a projection apparatus is provided. The projection apparatus includes an illumination system, a light valve, a light-homogenizing element, and a projection lens. The illumination system includes a chip package, a first dichroic film, a second dichroic film, and a third dichroic film. The chip package includes a first light-emitting chip capable of emitting a first light beam, a second light-emitting chip capable of emitting a second light beam, and a third light-emitting chip capable of emitting a third light beam. The first light-emitting chip, the second light-emitting chip, and the third light-emitting chip are arranged in a row. The second light-emitting chip is disposed between the first light-emitting chip and the third light-emitting chip, and the sizes of the first light-emitting chip and the third light-emitting chip are both smaller than the size of the second light-emitting chip. The first light beam, the second light beam, and the third light beam have mutually different colors. The first dichroic film is capable of deflecting the first light beam, the second dichroic film is capable of deflecting the second light beam, and the third dichroic film is capable of deflecting the third light beam. The first dichroic film, the second dichroic film, and the third dichroic film are not parallel to each other and do not cross each other. The first light beam, the second light beam, and the third light beam form an illumination light beam as the first light beam, the second light beam, and the third light beam respectively leaving the first dichroic film, the second dichroic film, and the third dichroic film. The light valve is disposed in the light path of the illumination light beam for transforming the illumination light beam into an image beam. The light-homogenizing element is disposed in the light path of the illumination light beam and between the first dichroic film, the second dichroic film, the third dichroic film, and the light valve. The projection lens is disposed in the light path of the image beam.

The embodiments of the invention have at least one of the following advantages. First, since the first dichroic film, the second dichroic film, and the third dichroic film do not cross each other, an ineffective region that fails to deflect light beams is no longer formed. In other words, a higher light-utilization efficiency is achieved. Besides, since the first dichroic film, the second dichroic film, and the third dichroic film are no need to be parallel to each other, the reflective angles of the first light beam, the second light beam, and the third light beam are allowed to be respectively controlled. This helps to cure deviations of incident angle and incident position resulting from off-axis of the left-sided first light-emitting chip and the right-sided third light-emitting chip, so as to make the first light beam, the second light beam, and the third light beam to leave the first dichroic film in parallel. In addition, since the first light-emitting chip, the second light-emitting chip, and the third light-emitting chip are in a same chip package and arranged in a row, the first light beam, the second light beam, and the third light beam are incident to the first dichroic film in an identical direction. In contrast, in the conventional projection apparatus, the red light, green light, and blue light are incident to the X-mirror in three respective directions. Hence, according to the row arrangement of light-emitting chips of this embodiment, the components are allowed to be disposed in the projection apparatus in a space-efficient way to reduce the occupied space of the projection apparatus. Besides, when the first light-emitting chip, the second light-emitting chip, and the third light-emitting chip are arranged in a row, a smaller combination of light-spots is obtained. Accordingly, different light paths may be arbitrarily selected according to the actual color or brightness demand.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a schematic diagram of a projection apparatus according to an embodiment of the invention. Referring toFIG. 1, in this embodiment, the projection apparatus10includes an illumination system12, a light valve14, and a projection lens16. The illumination system12includes a chip package22, a first dichroic film24, a second dichroic film26, and a third dichroic film28. The chip package22includes a first light-emitting chip221, a second light-emitting chip222, and a third light-emitting chip223arranged in a row. The first light-emitting chip221emits a first light beam221a, the second light-emitting chip222emits a second light beam222a, and the third light-emitting chip223emits a third light beam223a. In this embodiment, each of the first light-emitting chip221, the second light-emitting chip222, and the third light-emitting chip223is an LED chip. Alternatively, each of the first light-emitting chip221, the second light-emitting chip222, and the third light-emitting chip223is a laser diode chip or other suitable light-emitting chip. Further, in this embodiment, the chip package22further includes a lens224. The lens224covers the first light-emitting chip221, the second light-emitting chip222, and the third light-emitting chip223, and the lens224is disposed in the light paths of the first light beam221a, the second light beam222a, and the third light beam223a. Besides, the first light beam221a, the second light beam222a, and the third light beam223ahave mutually different colors. In this embodiment, the first light beam221amay be a red light beam, the second light beam222amay be a green light beam, and the third light beam223amay be a blue light beam. In an alternate embodiment, the first light beam221a, the second light beam222a, and the third light beam223amay have other colors different to the aforementioned colors.

In this embodiment, the first dichroic film24, the second dichroic film26, and the third dichroic film28are numbered for the proximity to the chip package22. The first dichroic film24is disposed in the light paths of the first light beam221a, the second light beam222a, and the third light beam223a. The second dichroic film26is disposed in the light paths of the second light beam222aand the third light beam223a. The third dichroic film28is disposed in the light path of the third light beam223a. The first dichroic film24, the second dichroic film26, and the third dichroic film28are not parallel to each other and do not cross each other. The first dichroic film24is disposed on a surface of a first transparent substrate34, the second dichroic film26is disposed on a surface of a second transparent substrate36, and the third dichroic film28is disposed on a surface of a third transparent substrate38. It is should be noted that the arrangement of the first dichroic film24, the second dichroic film26, and the third dichroic film28is not limited to the above embodiment. In an alternate embodiment, the first dichroic film24and the second dichroic film26are disposed on two opposite sides of the first transparent substrate34to thus omit the third transparent substrate38. The first dichroic film24reflects the first light beam221aand transmits the second light beam222a, and the second dichroic film26reflects the second light beam222a. The first dichroic film24and the second dichroic film26transmit the third light beam223a, and the third dichroic film28reflects the third light beam223a. When the first light beam221a, the second light beam222a, and the third light beam223aleave the first dichroic film24, the second dichroic film26, and the third dichroic film28respectively, the first light beam221a, the second light beam222a, and the third light beam223atogether form an illumination light beam I.

In addition, in this embodiment, the illumination system12further includes a light-homogenizing element42and a condenser lens44. The light-homogenizing element42and the condenser lens44are disposed in the light paths of the first light beam221a, the second light beam222a, and the third light beam223aand between the first dichroic film24and the light valve14. More specifically, the light-homogenizing element42may be a fly-eye lens for evenly spreading out the illumination light beam I on the light valve14. Besides, in this embodiment, the first light-emitting chip221, the second light-emitting chip222, and the third light-emitting chip223take turns to emit a light beam, so that the color of the illumination light beam I leaving the second dichroic film26is allowed to change over time. For example, the second light-emitting chip222first turns on and then off one times, then the first light-emitting chip221turns on and then off one times, and finally the third light-emitting chip223turns on and then off one times. These light-emitting chips alternately turn on and off in such order to allow the illumination light beam I leaving the second dichroic film26to represent green, red, and blue colors in succession. In an alternate embodiment, the first light-emitting chip221, the second light-emitting chip222, and the third light-emitting chip223may emit light beams simultaneously to allow the illumination light beam Ito represent a white color. The light valve14is disposed in the light path of the illumination light beam I for transforming the illumination light beam I into an image beam L. In this embodiment, the light valve14may be a digital micro-mirror device. However, in other embodiments, the light valve14may be a liquid-crystal-on-silicon panel, or a transmissive liquid crystal panel. A projection lens16is disposed in the light path of the image beam L to project the image beam L onto a screen (not shown). Moreover, in this embodiment, the projection apparatus10further includes a reflective mirror46disposed in the light path of the illumination light beam I and between the illumination system12and the light valve14. The reflective mirror46is allowed to bend the light path of the illumination light beam Ito more efficiently use the accommodation space of the projection apparatus10. Besides, a field lens48is disposed in the light path of the image beam L and between the light valve14and the projection lens16.

The embodiments of the invention have at least one of the following advantages. First, since the first dichroic film24, the second dichroic film26, and the third dichroic film28of the projection apparatus10do not cross each other, an ineffective region that fails to deflect light beams is no longer formed. In other words, the projection apparatus10has relatively high light-utilization efficiency. Besides, since the first dichroic film24, the second dichroic film26, and the third dichroic film28are no need to be parallel to each other, the reflective angles of the first light beam221a, the second light beam222a, and the third light beam223aare allowed to be respectively controlled. This helps to cure deviations of incident angle and incident position resulting from off-axis of the left-sided first light-emitting chip221and the right-sided third light-emitting chip223, so as to allow the first light beam221a, the second light beam222a, and the third light beam223ato leave the first dichroic film24in parallel. In addition, since the first light-emitting chip221, the second light-emitting chip222, and the third light-emitting chip223are in a same chip package22and arranged in a row, the first light beam221a, the second light beam222a, and the third light beam223aare incident to the first dichroic film24in an identical direction. In contrast, in the conventional projection apparatus, the red light, green light, and blue light are incident to the X-mirror in three respective directions. Hence, according to the row arrangement of light-emitting chips of this embodiment, the components are allowed to be disposed in the projection apparatus10in a space-efficient way to reduce the occupied space of the projection apparatus10. Besides, when the first light-emitting chip221, the second light-emitting chip222, and the third light-emitting chip223are arranged in a row, a smaller combination of light-spots is obtained.

FIGS. 2A to 2Cshow different embodiments of light paths for a projection apparatus, where three light-emitting chips are arranged in a row. Referring toFIGS. 2A to 2C, each dichroic film is not limited to reflect a specific color of light. For example, as shown inFIG. 2A, the first light beam221a, the second light beam222a, and the third light beam223aare respectively reflected by the third dichroic film28, the second dichroic film26, and the first dichroic film24. Particularly, according to the arrangement shown inFIG. 2Awhere green LED chip is placed in the middle of the red LED chip and blue LED chip, better spectral performance of light that passes through or is reflected by a dichroic film is obtained. Further, according to the arrangement shown inFIGS. 2B and 2Cwhere a green light beam is incident to the first dichroic film24, the light loss as a result of passing through a dichroic film is reduced to provide a higher amount of green light and thus to enhance the overall brightness. Also, in that case, since the green light beam is reflected by the first dichroic film24in advance, better spectral performance of red light and blue light that pass the dichroic films is obtained to improve the transmission of the red light and the blue light. Accordingly, different light paths may be arbitrarily selected according to the actual color or brightness demand.

FIG. 3shows a schematic diagram of a projection apparatus according to another embodiment of the invention. Referring toFIG. 3, the projection apparatus50includes a total-internal-reflection prism52disposed in the light paths of the illumination light beam I and the image beam L and between the light valve14and the projection lens16. More specifically, the total-internal-reflection prism52includes a first prism521and a second prism522, and a gap G exists between the first prism521and the second prism522to form a total reflection surface on the first prism521. The illumination light beam I from the light-homogenizing element42enters the first prism521through an incident face of the first prism521, and then reflected by the total reflection surface to the light valve14. Further, the image beam L from the light valve14passes through the first prism521, the gap G, and the second prism522in succession and then enters the projection lens16. In addition, as shown inFIG. 3, the second light-emitting chip222is disposed between the first light-emitting chip221and the third light-emitting chip223, and the size of the first light-emitting chip221and the size of the third light-emitting chip223are both smaller than the size of the second light-emitting chip222. As a result, the filed points formed by the first light-emitting chip221and the third light-emitting chip223are reduced, and the optical efficiency of the first light-emitting chip221and the third light-emitting chip223is improved.

Referring toFIG. 4, in one embodiment, the light-homogenizing element42is a fly-eye lens. The fly-eye lens includes a plurality of lens element421arranged in an array. Typically, a light path in which a light beam propagates in the projection apparatus is bent to thus deform the light spots formed on the light valve14. For example, as shown inFIG. 4, a rectangular-shaped lens element421′ forms a slanted light spot S′ in the shape of a slanted parallelogram on the light valve14, since the light beam leaving the lens element421′ is obliquely incident to the light valve14. Therefore, the desired lens element421is inversely shaped to slant toward a direction reverse to the slant direction of the slanted light spot S′. That is, each of the lens elements421has a shape complementary to the shape of a corresponding light spot deformed as a result of oblique incidence. Under the circumstance, each lens element421in turn forms a rectangular-shaped light-spot S on the light valve14to improve light-utilization efficiency and luminous uniformity.

In one embodiment, the condenser lens44is disposed in the light path of the illumination light beam I and between the light-homogenizing element42and the light valve14. A central axis N of the condenser lens44is away from an optical axis M of the projection apparatus10. For example, as shown inFIG. 5A, the central axis N of the condenser lens44is shifted some distance in an X-axis direction in relation to the optical axis M of the projection apparatus10. Alternatively, as shown inFIG. 5B, the central axis N is shifted some distance in a Y-axis direction in relation to the optical axis M. Through the eccentric design of the condenser lens44, a light path length within a confined space is increased and the shape of light spots is allowed to be adjusted. This may shrink the overall size of the projection apparatus and reduce the loss of light.