Abstract:
Disclosed is a mounting structure for a lamp comprising a lamp having a funnel, a frame attached to a front end of the funnel and a connecting bolt provided at a rear portion of the funnel a lamp holder, which is adapted to hold the lamp therein while maintaining a desired lateral gap at each of the frame of the lamp, have a bottom plate, a front plate and a pair of side plates. The lamp mounting structure maintains an alignment of the optical axis of the lamp while effectively preventing the lamp from being damaged due to a thermal expansion thereof.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a lamp mounting structure. More particularly to a lamp mounting structure capable of aligning the optical axis of a lamp correctly while preventing a lamp from being damaged even when it is overheated. Thereby, the invention enhances the stability in the operation of the lamp and improve convenience in association with the use of the lamp. In particular, the present invention can be effectively employed to the cases in which the alignment of the optical axis of a lamp is important, such as the lamp mounting structures of projectors. 
     2. Background of the Related Art 
     Generally, a display device using a projection system includes a projector for projecting the light retaining an image signal, and a screen for reflecting the light projected from the projector, thereby displaying an image. The projector mainly includes a lamp for performing a light emitting function, a plurality of dichroic mirrors for reflecting or transmitting the light (white light) emitted from the lamp selectively, a liquid crystal panel for receiving the light beams separated from the light by the dichroic mirrors, thereby forming an image while controlling the amount of the light incident on each pixel thereof, and projection lens for projecting the image formed by the liquid crystal panel while enlarging the image. 
     The lamp is an essential component of the projector since it determines the basic performance of the projector such as controlling the brightness and color of the image projected onto the screen. FIGS. 1 and 2 illustrate an embodiment of a conventional lamp. Referring to FIGS. 1 and 2, the lamp  10  includes a funnel  12  serving as a mirror, a frame  14  attached to the front end of the funnel  12 , an iron core  16  arranged at the rear portion of the funnel  12 , a neck  18  adapted to partially surround the iron core  16 , and a connecting bolt  19  protruded from the iron core  16 . Metal material such as iron could be used to make the iron core  16 . The iron core  16  is mounted on the neck  18  by a gypsum material interposed therebetween. 
     The brightness and the color of the image displayed by the projector vary greatly, depending on the direction of the light emitted from the lamp  10 . Accordingly, it is necessary to firmly maintain the mounted state of the lamp  10 . To this end, the lamp  10  is firmly and accurately mounted by a lamp holder  20  in order to prevent the optical axis of the lamp  10  from being miss-aligned in lateral, vertical and logitudina directions, the directions of X, Y, and Z axis in FIG. 1, respectively. 
     The lamp holder  20 , which serves as a mounting structure of the lamp  10 , has a bottom plate  201 , a front plate  202 , and a pair of side plates  203 . The guide plates  22  are placed at both sides of the front plate  202  to fasten the right and the left sides of the frame  14  to the lamp holder  20 . Vertically-extending guide plates  22  are provided at both sides of the rear surface of the front plate  202 . The guide plates  22  serves to the frame  14  of the lamp  10 , thereby holding the lamp  10  in the longitudinal, z-axid, and lateral, x-axis, directions. The lamp holder  20  also has a strip-shaped holding plate  30  mounted between the side plates  203  to hold the lamp  10  in the vertical, y-axis, direction. Both ends of the holding plate  30  are fitted in slots  203 , which are formed at the side plates  203 , respectively. 
     In the conventional lamp mounting structure having the above mentioned configuration, movements of the lamp  10  in lateral, x-axis directions are restricted by the guide plates of the lamp holder  20 , and movements of the lamp  10  in vertical, y-axis, directions are restricted by the holding plate  30 . Also, movements of the lamp  10  in longitudinal, z-axis, directions are restricted by the front plate  202  of the lamp holder  20  and stoppers that are provided at the lower end of the guide plates  22 . Thus, the movements of the lamp  10  are restricted to prevent the optical axis of the lamp  10  from miss-alignments in any direction. 
     Meanwhile, heat generated as a result of a high temperature, for example, about 300° C. or above, at the lamp  10  isdue to the operations of the lamp  10 . This heat serves to over-heat the lamp  10 , thereby causing the funnel  12  and the frame  14  to expand. When the funnel  12  and frame  14  expand, an excessive pressure is applied to the funnel  12  by the lamp holder  20 . Since the lamp  10  is placed in between the guide plates  22  of the lamp holder  20 , the expansion may result in a crack, either at the funnel  12  or the neck  18 . 
     If the width L 2 , the defined space between the guide plates  22 , increases in order to prevent the lamp  10  from being damaged due to a thermal expansion as described above, then the lamp  10  may move laterally resulting in a miss-alignment of the optical axis a normal state. Also, there may be a degraded uniformity of the image displayed on the screen. In particular, the miss-alignment of the optical axis causes the displayed image on the screen to undesirably exhibit undersirable excessive yellow color at the periphery thereof. 
     SUMMARY OF THE INVENTION 
     Therefore, the present invention has been made in view of the above mentioned problems. An object of the invention is to provide a lamp mounting structure for a projector which is capable of maintaining a desired alignment of the optical axis of a lamp included in the projector while allowing the lamp to move freely to an certian extent. Thereby the invention will be able to prevent the lamp from being cracked due to an expansion caused by an excessive heat, thus achieving an improved stability in the operation of the lamp. 
     In accordance with the present invention, the object is accomplished by providing a mounting structure for a lamp comprising: a lamp having a funnel, a frame attached to a front end of the funnel, and a connecting bolt provided at a rear portion of the funnel; a lamp holder, which is adapted to hold the lamp therein while maintaining a desired lateral gap at each side of the frame of the lamp, has a bottom plate, a front plate and a pair of side plates; and a guide that elastically supports the lamp in position comprises hinges formed at the opposite ends of the guide and mounted on the bottom plate of the lamp holder in a manner that allows the hinges to rotate, an engagement member arranged at an intermediate portion of the guide and placed at an upper end of the front plate of the lamp holder and a contact member that is formed at the opposite sides of the engagement member and comes in contact with the lamp. 
     The lamp mounting structure according to the present invention allows the lamp to be enlarged and shifted to a certain extent with the structure of the lamp holder. Therefore, this structure prevents either the funnel or the neck of the lamp from being cracked even when the lamp is heated. Accordingly, it is possible to lengthen the life of the product to which the lamp mounting structure is employed. In addition, the lamp mounting structure elastically holds the lamp using the structure of the tension guide. Accordingly, when the optical axis of the lamp is miss-aligned due to a shift of the lamp, this miss-alignment is immediately corrected. Thus, there is an advantage in that an improved stability in the operation of the product, for example, a projector, is achieved. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above objects, and other features and advantages of the present invention will become more apparent after a reading of the following detailed description when taken in conjunction with the drawings, in which: 
     FIG. 1 is an exploded perspective view illustrating a conventional lamp mounting structure; 
     FIG. 2 is an assembled perspective view illustrating the conventional lamp mounting structure; 
     FIG. 3 is an exploded perspective view illustrating a lamp mounting structure according to an embodiment of the present invention; and 
     FIG. 4 is an assembled perspective view illustrating a lamp mounting structure according to the embodiment of the present invention 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Now, preferred embodiments of the present invention will be described in accordance with FIGS. 3 and 4. In FIGS. 3 and 4, elements corresponding to those in FIGS. 1 and 2 are denoted by the same reference numerals. 
     In FIG. 3, a lamp mounting structure for a projector according to an embodiment of the present invention is illustrated. The lamp mounting structure includes a lamp holder  20  for holding a lamp  10 , and a return means for elastically returning the lamp  10  to an original position. By using the return means, the optical axis of the lamp  10  is aligned in all directions, when the lamp  10  moves away from the original position. 
     As mentioned above, the lamp  10  includes a funnel  12 , and a frame  14  provided at the front end of the funnel  12 . Basically, the lamp holder  20  has a bottom plate  201 , a front plate  202 , and a pair of spaced side plates  203 . In accordance with the present invention, the distance L 3  between the side plates  203  of the lamp holder  20  is slightly longer than the lateral length Lt of the frame  14  by about 1 mm. That is, the lamp holder  20  is structured to support the lamp  10  while maintaining a desired gap between the frame  14  and the side plate  203 . 
     The return means comprises a tension guide  40  having a curved structure to surround the side and upper surfaces of the funnel  12 . The tension guide  40  is hingably mounted to the bottom plate  201  of the lamp holder  20  at both ends thereof. The tension guide  40  also has an intermediate portion engaged with the front plate  202 , and the funnel and frame contact portions that are arranged at the opposite sides of the intermediate portion and are adapted to come into contact with the funnel  12  and frame  14  of the lamp  10 . The tension guide  40  may be a wire member, which is able to be bent to have a desired shape. This tension guide  40  has material and structural characteristics capable of exhibiting a desired elasticity. 
     The shape of the tension guide  40  will be described in detail. The tension guide  40  has a wire-shaped guide body, hinges  40 a respectively provided at the opposite ends of the guide body and mounted hingably to fixed members  24  mounted on the bottom plate  201 , a funnel contact portions  40   b  extending from respective hinges  40   a  and serving to come into contact with the funnel  12 , a frame contact portions  40   c  extending from the respective funnel contact portions  40   b  and serving to come into contact with the frame  14 , and an engagement portion  40   d  provided at the intermediate portion of the guide body and engaged with engagement grooves  20   a  formed at the upper end of the front plate  202 . 
     The tension guide  40  is mounted hingably to the bottom plate  201  using its hinges  40   a  mounted hingably to the fixed members  24 . Once the lamp  10  is arranged in position in the lamp holder  20 , the tension guide  40  is moved to engage its engagement portion  40   d  with the engagement grooves  20   a  formed at the upper end of the front plate  202 . Thus, the lamp  10  is firmly held in the lamp holder  20  by the tension guide  40 . 
     Four contacts  41  are formed between the lamp  10  and the tension guide  40  to define the position of the lamp  10  in the lamp holder  20 . 
     The principle of positioning the lamp  10  by the tension guide  40  will be described hereinafter. 
     As shown in FIG. 4, contacts  41 , a first contact  41   a  and a second contact  41   b , are formed at each side of the lamp  10  between the funnel  12  and an associated funnel contact portions  40   b . In FIG. 4, the tension guide  40  applies a force to the lamp  10  in leftward, rearward, and downward directions at the first contact  41   a , while applying a force to the lamp  10  in left, rearward, and upward directions at the second contact  41   b . Although not shown, the force of the tension guide  40  is applied to the left side of the lamp  10  in symmetrical directions to the force applied to the right side of the lamp  10 . 
     The forces applied to the lamp  10  by the tension guide  40  are symmetric in a vertical, y-axis, direction and a lateral, x-axis, direction, so that they are offset by each other. Also, the force of the tension guide  40  in a longitudinal, z-axis, direction is applied to the front plate  202 . Thus, the lamp  10  is firmly held in the lamp holder  20  in a state in which the forces applied to the lamp  10  by the tension guide  40  are balanced. When the force&#39;s balance is lost due to a positional shift of the lamp  10 , a return force from the tension guide  40  is applied to the lamp at the contacts  41 . With the return force, the lamp  10  is immediately moved to its original position where the optical axis of the lamp  10  is aligned in all directions. Thus, a desired alignment of the optical axis of the lamp  10  can be easily achieved. 
     The tension guide  40  may be structured to form additional contacts  41   c  and  41   d  where the frame contact portions  40   c  come into contact with the upper surface of the frame  14 . In this case, a force from the tension guide  40  is applied downward to the frame  14  against the bottom plate  201 . With this force, the lamp  10  can be held more firmly in the vertical direction. 
     In accordance with the lamp mounting structure having the above mentioned configuration, the lamp  10  is laterally movable to some extent in which the frame  14  of the lamp  10  is in contact with the front plate  202  of the lamp holder  20 . Accordingly, even when the funnel  12  and frame  14  are deformed to have an enlarged size or are shifted due to the heat generation during the operation of the lamp  10 , such phenomenon is absorbed by the tension guide  40  using the elasticity of the tension guide  40 . Accordingly, there will be no crack in either the funnel  12  or hte neck  18 . 
     In particular, when the lamp  10  is shifted resulting in a miss-alignment of the optical axis thereof, the tension guide  40  applies an elastic pressure to the lamp  10  in a direction opposite to the shift direction of the lamp  10 . Also, its structure surrounds the left and right side surfaces and upper surface of the funnel  12 . Accordingly, the position of the lamp  10  is immediately corrected. Thus, the optical axis of the lamp  10  is maintained in lateral, vertical and longitudinal directions, X, Y, and Z-axis directions, respectively. 
     The lamp mounting structure according to the present invention allows the lamp to be enlarged and shifted to a some extent having the structure including the lamp holder preventing the funnel or the neck of a lamp from being cracked even when the lamp is heated. Accordingly, it is possible to lengthen the life of the product to which the lamp mounting structure is applied. In addition, the lamp mounting structure holds the lamp elastically with the structure of the tension guide. Accordingly, when the optical axis of the lamp is mis-aligned due to a shift of the lamp, this mis-alignment is immediately corrected. Therefore, the improved stability in the operation of the product, for example, a projector, is achieved. 
     Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.