Patent Application
20070086094
1. Field of the Invention
The invention relates to a prism assembly and method for forming an air gap thereof, and in particular relates to an optical element assembly capable of refracting light beams or chromatographically splitting light beams.
2. Description of the Related Art
With the rapid development of projectors in different fields, such as large projection systems in the large forum and projection monitors or TVs in a commercial setting, projectors are popularly used for display.
In
The refractive device 40 includes two total internal reflection prisms (TIR prisms) 41′ and 42′. A mirroring surface 410′ formed on the prism 41′. Before the light beam is projected to the screen 70, the light beam is, transmitted via the sequence of the DMD 50, the prism 41′ and the prism 42′. Thus, a gas gap must be formed between the prisms 41′ and 42′ for total internal reflection on the mirroring surface 410′ of the prism 41′ and to prevent the initial light beam entering the prisms 41′ from directly entering the prism 42′.
In general, the gas gap between the prisms 41′ and 42′ can be formed by placement of an adhesive mixed with objects having a predetermined height; or an adhesive adhering a coated film or layer therebetween. U.S. Pat. No. 4,138,192 discloses that a transparent adhesive is placed between two prisms and a refractive index difference between the prisms and the transparent adhesive causing total reflection is applied to a scope.
In
In
The adhesive 80 is a glue or soft material. However, the thickness of the adhesive 80 between the assembled prisms 41′ and 42′ cannot be easily controlled, i.e., the gas gap between the assembled prisms 41′ and 42′ cannot be precisely formed. Further, excess adhesive 80 outflows from the surfaces 410′ and 420′ of the prisms 41′ and 42′ when a exterior force is applied to the prisms 41′ and 42′, and the light path 46 of the prisms 42′ shown in
A detailed description is given in the following embodiments with reference to the accompanying drawings.
The feature of the invention is to provide a prism assembly and method for forming an air gap thereof to precisely control the thickness of the gas gap of the prism assembly in order to uniformize the adhesive between the prisms, to improve the rate of use of the light beams, to keep excess adhesive from the surface of the prisms away from a light path, and to increase availability of the projection system.
The invention provides a prism assembly and method for forming an air gap thereof. At least one recess is formed on at least one surface of a conjunction portion of two prisms. The recess is located at a region having a predetermined distance with respect to an edge of the surface. An adhesive applied between the recess and the edge of the surface is used to adhere the prisms each other to form the air gap therebetween.
The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
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 assembly of the projection system and the principle of imaging are disclosed in the described related art. The invention provides a prism assembly M to improve the rate of use of the light beams of the refractive device 40 composed of the prisms 41′ and 42′ in
As shown in
In this embodiment, the second prism 42 provides two recesses 48 oppositely located at the predetermined distance d1 with respect to the edges 420e of the conjunction portion 44, the length of the recesses 48 can be equal to or smaller than that of the edges 420e of the conjunction portion 44, and the recess 48 can be formed by a cutting device such as diamond grinder or tool machine, or etching by chemical material. In other embodiments, the recess can be formed on the first surface 410 of the first prism 41.
Note that the recess 48 must be located between the edge 420e and a light path 46, and the recess 48 is kept at a desired distance from the conjunction portion 44 and the light path 46, respectively. Thus, the adhesive 80 is applied on the region between the recess 48 and the edge 420e of the conjunction portion 44, to keep the recess 48 away from the light path 46.
In
When the first and second prisms 41 and 42 are bonded by the adhesive 80, the adhesive 80 can be solidified by a curing step. In other embodiments, the bonding material 49 can be UV glue. Note that the thickness of the spacers 47 is the same as the distance of the gas gap 401 between the first and second prisms 41 and 42.
The adhesive 80 formed by the bonding material 49 and the spacers 47 is applied on the first or second prism 41 or 42 so that the excess adhesive 80 outflowed from the surface of the first or second prism 41 or 42 can be removed by a centrifugal force formed by a rotating disk (not shown). The adhesive 80 coated on the first and second prism 41 or 42 is uniformed and the spacers 47 can be averagely deployed on the first and second prisms 41 or 42 to prevent the excess adhesive 80 from flowing out when the first and second prisms 41 and 42 are pressed and to prevent pollution of the light path 46.
Thus, the invention provides a uniform gas gap 401 between the first and second prisms 41 and 42, to overcome the problems of the related arts shown in
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 94135705 | Oct 2005 | TW | national |
