BRIEF DESCRIPTION OF THE DRAWINGS
The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
FIG. 1A is a front view of a conventional color wheel;
FIG. 1B is a side view of the color wheel of FIG. 1A;
FIG. 2 is a front view of a color wheel of a first embodiment of the invention;
FIG. 3 is a front view of a color wheel of a second embodiment of the invention;
FIG. 4 is a front view of a color wheel of a third embodiment of the invention;
FIG. 5A is a front view of a color wheel of a fourth embodiment of the invention;
FIG. 5B is a side view of the color wheel of FIG. 5A; and
FIG. 5C is a partially enlarged view of zone (z) of FIG. 5B;
DETAILED DESCRIPTION OF THE INVENTION
The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
The invention provides a projection system for forming an image. The projection system includes a light source generating a light beam, a color wheel used for performing color separation on the light beam of the light source, and a digital micromirror element used for reflecting the filtered light beam of the light source from the color wheel to form the image. The color wheel includes a motor having a shaft (not shown) and color filters disposed around the motor. The following description is of four color wheels 20, 30, 40 and 30A of the invention.
In FIG. 2, a color wheel 20 of a first embodiment of the invention includes a carrier 4a, a plurality of color filters fixedly disposed around the carrier 4a to form at least one gap Xa, and a balancer 6 disposed at the carrier 4a corresponding to the gap Xa. The carrier 4a is centrally pivoted to the shaft of the motor so that the color wheel 20 can be driven by the motor. In this embodiment, the number of the color filters is three, including red, green and blue one, labeled by symbols “R”, “G” and “B”, respectively. The color filters are fixedly disposed around the peripheral of the carrier 4a, and the gap Xa is located between the red and blue color filters “R” and “B”.
In comparison with FIG. 1A, it is understood that the color wheel 20 differs from the color wheel 10 of FIG. 1A in that the transparent filter “W” of the color wheel 10 is directly replaced by the gap Xa to reduce the loss of light transmission rate when the light beam pass through the transparent filter “W” of the color wheel 10.
The balancer 6 disposed at the carrier 4a corresponding to the gap Xa forms a moment couple with respect to the red, green and blue color filters “R”, “G” and “B”, to balance the weight thereof, to keep center of mass of the color wheel 20 maintaining at the geometric rotation center of the color wheel 20, and to avoid vibration and noise from the high-speed rotational color wheel 20. In this embodiment, the balancer 6 can be made of plastic, rubber or metal, and the shape of the balancer 6 can be sectional or circular.
In FIG. 3, a color wheel 30 of a second embodiment of the invention includes a carrier 4b and two sets of three-color filters “R”, “G” and “B” fixedly disposed around the carrier 4b at a peripheral thereof to form two corresponding gaps Xb, instead of the transparent filter “W” of the color wheel 10 of FIG. 1A. In this embodiment, the two corresponding gaps Xb have the same size. Note that the described balancer 4 or the like can be optionally eliminated if the corresponding gaps have the same size, and a moment couple can be formed therebetween to balance the rotational color wheel 30.
In FIG. 4, a color wheel 40 of a third embodiment of the invention includes a carrier 4c and three spaced color filters “R”, “G” and “B” fixedly disposed around the carrier 4b at a peripheral thereof to symmetrically form three gaps Xc having a central line cl, and an angle φ is formed between the central lines cl of the gaps Xc with respect to a center of the carrier 4c, instead of the transparent filter “W” of the color wheel 10 of FIG. 1A. In this embodiment, the three gaps Xc have the same size, and the angle φ formed between two adjacent central lines cl is 120 degree. Note that the number of the gap Xc is not limited to the disclosed embodiment, and the gaps Xc can be asymmetrically arranged with respect to the center of the carrier 4c as a moment couple can be formed on the color wheel 40 to balance the rotational color wheel 30, such as the use of the described balancer 6.
In FIGS. 5A-5C, a color wheel 30A of a fourth embodiment of the invention is presented. The color wheel 30A of FIG. 5A differs from the color wheel 30 of FIG. 3 in that the color wheel 30A further includes a fixing ring 8 disposed along edges of the color filters “R”, “G” and “B” to increase the stabilization of the rotational color wheel 30A. Furthermore, as shown in FIGS. 5B and 5C, the fixing ring 8 extends to one side of the color filters “R”, “G” and “B”. It is to be understood that the fixing ring 8 is not limited to be disposed along edges of the color filters “R”, “G” and “B” of the color wheel 30 of FIG. 3. Similarly, the fixing ring 8 is capable of being disposed on the color wheels 20 and 40 shown in FIG. 2 and 4, respectively. In this embodiment, the fixing ring 8 is made of plastic, rubber or metal.
Thus, it is to be understood that the shape of the carrier is not limited to the circular one and the connection between the carrier and the color filters is not limited to the bonding. The color filters can be fixedly disposed at the periphery of the carrier by adhesion, jacketing or equivalent bonding methods.
While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
Patent Application
20070273841
