The above aspects and features of the present invention will be more apparent by describing certain embodiments of the present invention with reference to the accompanying drawings, in which:
The first pitch P1 of the adjusting ring male screw part 311 may be different from the second pitch P2 of the adjusting ring female screw part 321. According to an aspect of the present invention, the first pitch P1 may be 1 mm, and the second pitch P2 may be 0.5 mm.
The first and second pitches P1 and P2 may vary depending on sizes of lenses of the projection optical system, and a ratio between the first and second pitches P1 and P2 may be changed into a different ratio. The second pitch P2 may be larger than the first pitch P1.
A BFL position shift of the body tube 200 satisfies Equation 1:
BFL Position Shift=(First Pitch (P1)−Second Pitch (P2))×Rotation Angle/360 (1)
For example, if the adjusting ring 300 rotates once (through 360°), the first pitch P1 is 1 mm, and the second pitch P2 is 0.5 mm. Thus, the BFL shift of the body tube 200 is +0.5 mm.
According to an aspect of the present invention, if the adjusting ring 300 is rotated to adjust a BFL of the body tube 200, a body tube rotation preventing unit 400 may be further included to prevent the body tube 200 from rotating due to the rotation of the adjusting ring 300.
The body tube rotation preventing unit 400 includes a slit 410 formed in the frame 100 and a screw 430.
The slit 410 penetrates the frame 100 in a direction parallel with the optical axis as shown in
The body tube 200 is installed in the frame 100 to be moved by the adjusting ring 300. The body tube 200 performs a sliding operation with a rotation of the adjusting ring 300 to advance and retreat based on an optical axis. Black focal lengths (BFLs) of a plurality of lenses installed in the body tube 200 are adjusted by the sliding operation. For this purpose, a body tube male screw part 210 having a second pitch P2 is formed on a portion of the surface of the body tube 200 and screwed to the adjusting ring 300.
A flange 220 is formed on the body tube 200 in a position adjacent to the body tube male screw 210 to prevent the body tube 200 from being excessively inserted into the frame 100 during adjusting of the BFLs of the body tube 200 using the rotation of the adjusting ring 300.
Portions of parts, which are adjacent to and interfere with the body tube 200, may be eliminated to make a digital light processing (DLP) engine compact. For example, a front lens 201, which may interfere with an illumination lens (not shown) forming an illumination optical system, may be D-cut as shown in
The adjusting ring 300 includes a first tube part 310 and a second tube part 320 having a larger diameter than the first tube part 310.
The first tube part 310 includes an adjusting ring male screw part 311 corresponding to the frame female screw part 110 having the first pitch P1, and the second tube part 320 includes an adjusting ring female screw part 321 corresponding to the body tube male screw part 210 having the second pitch P2. An uneven part 330 is formed on the surface of the second tube part 320 to prevent the second tube part 320 from slipping out of the user's hand.
Certain embodiments of the present invention will be described in greater detail with reference to the accompanying drawings.
In the following description, same drawing reference numerals are used for the same elements in different drawings. The matters defined in the description such as a detailed construction and elements are provided to assist in a comprehensive understanding of the invention. It is apparent that the present invention can be carried out without those detailed defined matters. Also, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.
Referring to
A body tube installing part 102 is provided in the frame 100 and connected to a front projection lens assembly 600 and a reflecting mirror 700, which will be described later with reference to
A diameter D1 of the body tube installing part 102 is equal to a diameter D2 of the body tube 102, and the body tube installing part 102 has a very small tolerance to prevent an optical axis from swaying. Also, a frame female screw part 110 having a first pitch P1 is formed on an inner surface of an entrance 101 of the body tube installing part 102 so that the adjusting ring 300 is screwed to the frame male screw 110.
The body tube 200 receives light including image information from an illumination optical system (not shown), magnifies and focuses the light at a predetermined magnification, and transmits the light to a projection lens 610 installed at the front projection lens assembly 600 shown in
The screw 430 may be screwed to the body tube 200 through a guide member 420 as shown in
A projection optical system having a focusing apparatus of an optical projection device according to an embodiment of the present invention will now be described.
The projection optical system according to the present embodiment includes a rear projection lens assembly 500 and a front projection lens assembly 600. The rear projection lens assembly 500 receives light from an illumination optical lens assembly (not shown) and an image from a digital micro-mirror device (DMD) module (not shown) and magnifies and focuses the light and the image. The image magnified and focused by the rear projection lens assembly 500 is transmitted to the front projection lens assembly 600 through a reflecting mirror 700 and then projected onto a screen (not shown).
The rear projection lens assembly 500 includes the frame 100, the body tube 200, and the adjusting ring 300. The frame 100 includes the frame female screw part 110 having the first pitch P1. The body tube 200 is moveably installed in the frame 100 and includes the body tube male screw part 210 having the second pitch P2. The adjusting ring 300 includes the adjusting ring male screw part 311 corresponding to the frame female screw part 110 having the first pitch P1 and the adjusting ring female screw part 321 corresponding to the body tube male screw part 210 having the second pitch P2.
The adjusting ring 300 supports the body tube 200 in the frame 100 and moves the body tube 200 toward the optical axis direction so as to adjust the BFLs of the lenses installed in the body tube 200.
The front projection lens assembly 600 includes the projection lens 610 which projects the image magnified and focused by the rear projection lens assembly 560 onto the screen.
If the projection optical system has the above-described structure, the adjusting ring 300 adjusts the BFL of the body tube 20 and simultaneously fixes the body tube 200 to the frame 100. Thus, a number of parts of the projection optical systems can be reduced.
When the adjusting ring 300 is rotated to adjust the BFL of the body tube 200, the body tube 200 may not rotate with the adjusting ring 300 and may move back and forth toward a direction parallel with an optical axis. Thus, the BFL of the body tube 200 may be stably and precisely adjusted even in the projection optical system in which the body tube 200 cannot rotate as when a lens installed in the body tube 200 is D-cut.
Also, the second pitch P2 is denser than the first pitch P1. Thus, a shift distance of the body tube 200 may be further precisely adjusted. In other words, if the first pitch P1 is 1 m and the second pitch P2 is 0.5 mm as in the previous embodiment, the body tube 200 may move by about 0.0027 mm toward the optical axis direction when the adjusting ring 300 rotates through 1°. Thus, the BFL can be very precisely adjusted.
As described above, according to the present invention, a body tune can be supported in a frame using a member, i.e., an adjusting ring, and simultaneously a BFL of the body tube can be adjusted. Thus, a focusing apparatus for focusing the BFL of the body tube can be constituted using a small number of parts. As a result, the focusing apparatus can be simply assembled, and its manufacturing cost can be reduced.
Also, the adjusting ring can have different pitches to minutely move the body tube with the rotation of the adjusting ring. As a result, the BFL can be further precisely adjusted.
The foregoing embodiment and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. Also, the description of the embodiments of the present invention is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.
Number | Date | Country | Kind |
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10-2006-0057039 | Jun 2006 | KR | national |