Patent Publication Number: US-2009225284-A1

Title: Projection lens module and optical projector

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial no. 97107844, filed on Mar. 6, 2008. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a projection lens module, in particular, to a projection lens module applied to an optical projector. 
     2. Description of Related Art 
     Current optical projectors, e.g. single beam projectors and liquid crystal display (LCD) projectors, may project images with high definition and high brightness. In addition, the optical projectors have advantages of lower price which is similar to that of the conventional television (TV) sets, small volume, and easy to carry. Therefore, the optical projector is increasingly accepted by most people in the society. 
     The sizes of a projection screen and the distance of the projection screen relative to a optical projector may be limited by the space of the environment where they are used. Therefore, an adjusting ring for focusing or zooming may be disposed on a projection lens of an optical projector, such that the user may use the adjusting ring to adjust the size or the definition of the image projected by the projection lens. 
       FIG. 1A  is a schematic exploded view of part of components of a conventional projection lens module.  FIG. 1B  is a schematic assembly view of the projection lens module of  FIG. 1A . Referring to  FIGS. 1A and 1B , the conventional projection lens module  100  includes a projection lens  110  and a zoom ring  120 . The projection lens  110  includes a lens barrel  112 , an adjusting pin  114 , and an optical lens module  116 . The adjusting pin  114  is disposed outside the lens barrel  112 , and the optical lens module  116  is disposed in the lens barrel  112 . The zoom ring  120  has a sliding slot  122  corresponding to the adjusting pin  114 . Before the zoom ring  120  is assembled to the lens barrel  112 , the sliding slot  122  is firstly aligned with the adjusting pin  114 , for correctly assembling the zoom ring  120  to the lens barrel  112 . After the zoom ring  120  is assembled to the lens barrel  112 , the zoom ring  120  may rotate relative to the lens barrel  112 , and the sliding slot  122  drives the adjusting pin  114  to move along an axis D 1 , and thus part of the optical lens module  116  moves along the axis D 1 . Therefore, the rotation of the zoom ring  120  may adjust the size of the image projected by the projection lens  110 . 
     However, due to the limitation of an arc length R of the sliding slot  122 , the maximum angle at which the zoom ring  120  rotates is only about 90 degrees. In other words, the adjustment travel of the zoom ring  120  is limited by the arc length R of the sliding slot  122 . 
     SUMMARY OF THE INVENTION 
     The present invention provides a projection lens module and an optical projector in which the adjustment travel of the adjusting ring is larger and of which the assembly is easier. 
     Other advantages and objects of the present invention can be further comprehended through the technical features disclosed in the present invention. 
     In order to achieve one or part of or all the objectives or other objectives, in an embodiment of the present invention, a projection lens module including a projection lens, a first transmission gear, and an adjusting ring is provided. The projection lens has a lens barrel, a driving ring, and an optical lens module. The driving ring has a plurality of first external teeth and rotates about a first axis. The driving ring is circularly disposed at the lens barrel. The optical lens module is disposed in the lens barrel. When the driving ring rotates, part of the optical lens module moves along the first axis. The first transmission gear has a plurality of second external teeth and rotates about a second axis. The first transmission gear is geared to the driving ring. The adjusting ring has a plurality of first internal teeth and rotates about a third axis. The adjusting ring drives the driving ring through the first transmission gear. 
     In an embodiment of the present invention, an optical projector including a casing, an illumination system, a light valve, and the above projection lens module is provided. The casing has another opening. The illumination system is disposed in the casing and suitable for emitting an illumination beam. The light valve is disposed in the casing and located in a transmission path of the illumination beam. The light valve is suitable for converting the illumination beam into an image beam. The projection lens module is joined with the casing, and the projection lens of the projection lens module is located in a transmission path of the image beam and suitable for projecting the image beam onto a screen through the other opening above mentioned. 
     The adjusting ring may drive the driving ring through the first transmission gear, so the adjustment travel of the adjusting ring may be rotated to 360 degrees according to the design requirements. Therefore, the adjustment travel of the adjusting ring is larger. In addition, the adjusting ring is a ring-shaped structure, and the axis of the adjusting ring coincides with the axis of the driving ring, so the manner of assembling the adjusting ring to the projection lens is easier. 
     Other objectives, features and advantages of the present invention will be further understood from the further technological features disclosed by the embodiments of the present invention wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings provide a further understanding of embodiments of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of embodiments of the invention. 
         FIG. 1A  is a schematic exploded view of part of components of a conventional projection lens module. 
         FIG. 1B  is a schematic assembly view of the projection lens module of  FIG. 1A . 
         FIG. 2  is a schematic cross-sectional view of an optical projector according to an embodiment of the present invention. 
         FIG. 3A  is a schematic exploded view of part of components of a projection lens module of  FIG. 2 . 
         FIG. 3B  is a schematic view illustrating a first transmission gear of  FIG. 3A  assembled to a projection lens. 
         FIG. 3C  is a schematic assembly view of the projection lens module of  FIG. 3A . 
         FIG. 4  is a schematic view illustrating relative positions of a driving ring, the first transmission gear, and an adjusting ring of  FIG. 3A  after being assembled. 
         FIG. 5  is a schematic view illustrating an assembly relationship of part of a fixed ring and the projection lens according to an embodiment of the present invention. 
         FIG. 6  is a schematic view illustrating a gearing relationship of the driving ring, the first transmission gear, and the adjusting ring according to another embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” etc., is used with reference to the orientation of the Figure(s) being described. The components of the present invention can be positioned in a number of different orientations. As such, the directional terminology is used for purposes of illustration and is in no way limiting. On the other hand, the drawings are only schematic and the sizes of components may be exaggerated for clarity. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. Similarly, the terms “facing,” “faces” and variations thereof herein are used broadly and encompass direct and indirect facing, and “adjacent to” and variations thereof herein are used broadly and encompass directly and indirectly “adjacent to”. Therefore, the description of “A” component facing “B” component herein may contain the situations that “A” component directly faces “B” component or one or more additional components are between “A” component and “B” component. Also, the description of “A” component “adjacent to” “B” component herein may contain the situations that “A” component is directly “adjacent to” “B” component or one or more additional components are between “A” component and “B” component. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. 
       FIG. 2  is a schematic cross-sectional view of an optical projector according to an embodiment of the present invention. Referring to  FIG. 2 , an optical projector  20  of this embodiment includes a casing  22 , an illumination system  24 , a light valve  26 , and a projection lens module  200 . The casing  22  has a first opening  22   a,  and the illumination system  24  is disposed in the casing  22  and suitable for emitting an illumination beam L 1 . The light valve  26  is disposed in the casing  22  and located in the transmission path of the illumination beam L 1 . The light valve  26  is suitable for converting the illumination beam L 1  into an image beam L 2 . The projection lens module  200  is disposed on the casing  22 , and is located in the transmission path of the image beam L 2 . The projection lens module  200  is suitable for projecting the image beam L 2  onto a screen S through the first opening  22   a.    
       FIG. 3A  is a schematic exploded view of part of components of a projection lens module of  FIG. 2 .  FIG. 3B  is a schematic view illustrating a first transmission gear of  FIG. 3A  assembled to a projection lens.  FIG. 3C  is a schematic assembly view of the projection lens module of  FIG. 3A .  FIG. 4  is a schematic view illustrating relative positions of a driving ring, the first transmission gear, and an adjusting ring of  FIG. 3A  after being assembled. Referring to  FIGS. 3A ,  3 B,  3 C, and  4 , the projection lens module  200  includes a projection lens  210 , a first transmission gear  220 , and an adjusting ring  230 . The projection lens  210  has a lens barrel  212 , a driving ring  214 , and an optical lens module  216 . As far as the arrangement relationship of the driving ring  214  and the optical lens module  216  relative to the lens barrel  212  is concerned, the driving ring  214  is circularly disposed at the lens barrel  212 . The optical lens module  216  includes a first lens group and a second lens group, the first lens group includes a plurality of optical lenses disposed in the lens barrel  212  and the second lens group includes a plurality of other optical lenses disposed in the lens barrel  212 . 
     Further, the driving ring  214  has a plurality of first external teeth T 1  and rotates about a first axis A 1 . When the driving ring  214  rotates, part of the optical lens module  216  moves along the first axis A 1 . In detail, when the driving ring  214  is a focus ring and rotates about the first axis A 1 , the focus ring may drive the first lens group to move along the first axis A 1 , so as to change the focusing state of the projection lens  210 . If the driving ring  214  is a zoom ring and rotates about the first axis A 1 , the zoom ring may drive the second lens group to move along the first axis A 1 , so as to zoom out or zoom in an image projected by the projection lens  210 . 
     The first transmission gear  220  has a plurality of second external teeth T 2 . The first transmission gear  220  rotates about a second axis A 2 , and the first transmission gear  220  is geared to the driving ring  214 . The adjusting ring  230  has a plurality of first internal teeth I 1  and rotates about a third axis A 3 , and the adjusting ring  230  may drive the driving ring  214  through the first transmission gear  220 . In this embodiment, the first axis A 1  coincides with the third axis A 3 , and the first axis A 1  is parallel to the second axis A 2 . The first internal teeth I 1  of the adjusting ring  230  is geared to the second external teeth T 2  of the first transmission gear  220 . The second external teeth T 2  of the first transmission gear  220  is geared to the first external teeth T 1  of the driving ring  214 . In addition, at least part of the first transmission gear  220  is located between the adjusting ring  230  and the driving ring  214 . 
     The adjusting ring  230  may drive the driving ring  214  through the first transmission gear  220 , so the adjustment travel of the adjusting ring  230  may be designed to rotate in a range of 0 degrees to 360 degrees as required. Therefore, as compared with the prior art, the adjustment travel of the adjusting ring  230  of this embodiment is larger. In addition, the adjusting ring  230  is a ring-shaped structure, and the first axis A 1  coincides with the third axis A 3 . Thus, as compared with the prior art, the manner of assembling the adjusting ring  230  to the projection lens  210  is easier. 
     In this embodiment, the projection lens module  200  further includes a fixed ring  260 . The fixed ring  260  is fixed at the lens barrel  212 , and the first transmission gear  220  is axially disposed at the fixed ring  260 .  FIG. 5  is a schematic view illustrating an assembly relationship of part of a fixed ring and the projection lens according to an embodiment of the present invention. Referring to  FIGS. 3A ,  3 B, and  5 , the fixed ring  260  of this embodiment includes a top base  260   a,  a bottom base  260   b,  and two fixing bases  260   c.  In addition, the fixed ring  260  has a second opening  262  located at the top base  260   a.  The top base  260   a  and the bottom base  260   b  may be assembled to be circularly disposed at the lens barrel  212 . When the top base  260   a  is embedded into the lens barrel  212  along an assembling path P 1  in  FIG. 5 , the second opening  262  exposes at least part of the first external teeth T 1  of the driving ring  214 . In addition, the fixing bases  260   c  are respectively fixed at two opposite sides of the top base  260   a.  Two fixing elements  220   d  of the first transmission gear  220  may be respectively screwed at the fixing bases  260   c,  such that a bearing  222  of the first transmission gear  220  is positioned on the top base  260   a.  In addition, the first transmission gear  220  is geared to driving ring  214  through the second opening  262 . 
     Referring to  FIGS. 3B and 3C , in this embodiment, the projection lens module  200  further includes a limit ring  270  and a limit element  280 . The limit ring  270  is circularly disposed and fixed at the fixed ring  260 , and the limit element  280  is fixed outside the lens barrel  212 . In this embodiment, the limit ring  270  and the fixed ring  260  are integrally formed, and the limit element  280  is fixed at one of the fixing bases  260   c  of the fixed ring  260 . Thus, part of the first internal teeth I 1  of the adjusting ring  230  is limited between the limit ring  270  and the limit element  280 . Therefore, the adjusting ring  230  does not easily become loose along the third axis A 3 . 
       FIG. 6  is a schematic view illustrating a gearing relationship of the driving ring, the first transmission gear, and the adjusting ring according to another embodiment. In another embodiment, the projection lens module  200 ′ further includes a second transmission gear  240  and a third transmission gear  250 . The second transmission gear  240  has a plurality of third external teeth T 3 , and the second transmission gear  240  rotates about a fourth axis A 4 . The first axis A 1 , the second axis A 2 , the third axis A 3 , and the fourth axis A 4  are parallel to one another, and the second transmission gear  240  is geared to the first transmission gear  220  and the adjusting ring  230 . The third transmission gear  250  has a plurality of fourth external teeth T 4  and rotates about the third axis A 3 . The third transmission gear  250  is geared to the second transmission gear  240 . 
     In detail, at least part of the second transmission gear  240  is located between the adjusting ring  230  and the third transmission gear  250 . When the adjusting ring  230  rotates, the first internal teeth I 1  of the adjusting ring  230  drive the third external teeth T 3  of the second transmission gear  240 . The third external teeth T 3  of the second transmission gear  240  then drives the second external teeth T 2  of the first transmission gear  220 . The second external teeth T 2  of the first transmission gear  220  then drives the first external teeth T 1  of the driving ring  214 . 
     To sum up, the projection lens module and the optical projector of the embodiments of the present invention at least have one of the following advantages. 
     1. The adjusting ring may drive the driving ring through the first transmission gear, so the adjustment travel of the adjusting ring may be designed to rotate to 360 degrees as required. Therefore, as compared with the prior art, the adjustment travel of the adjusting ring of the embodiment is larger. 
     2. The adjusting ring is a ring-shaped structure, and the axis of the adjusting ring may coincide with the axis of the driving ring. Therefore, as compared with the prior art, the manner of assembling the adjusting ring to the projection lens according to the above embodiments is easier, thus increasing the convenience for the user. 
     The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable persons skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. Therefore, the term “the invention”, “the present invention” or the like does not necessarily limit the claim scope to a specific embodiment, and the reference to particularly preferred exemplary embodiments of the invention does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is limited only by the spirit and scope of the appended claims. The abstract of the disclosure is provided to comply with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Any advantages and benefits described may not apply to all embodiments of the invention. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the present invention as defined by the following claims. Moreover, no element and component in the present disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.