Abstract:
A focus regulator is provided for simplifying and minimizing the structure of an image projector. The focus regulator includes a controller rotatably formed on a main body to be limitedly movable in the direction of the optical axis. A focus lens unit is affixed to the projection lens unit of the main body to be movable in the direction of the optical axis (OX) by being rotated with the controller.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit under 35 U.S.C. § 119(a) of Korean Patent Application No. 2005-19666, filed Mar. 9, 2005, in the Korean Intellectual Property Office, the entire disclosure of which are hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a projection apparatus, such as a projector. More specifically, the present invention relates to a focus regulator of a projection apparatus for adjusting the focus of an image projected onto a screen.  
         [0004]     2. Description of the Related Art  
         [0005]     Conventionally, a projection apparatus is a displaying device designed for enlarging and projecting an optical image generated from an image formation unit onto a projection surface, such as a screen.  
         [0006]     The projection apparatus generally includes an illuminating optical system for generating light, an image formation unit for converting the light generated by the illuminating optical system into an optical image, and a projection system for enlarging and projecting the optical image converted by the image formation unit onto a projection surface. Additionally, the projection system includes a first lens unit for an incident optical image generated by the image formation unit, and a second lens unit for projecting an optical image passing through the first lens unit onto a projection surface.  
         [0007]     Additionally, the projection apparatus includes a focus regulator for adjusting the focus of the optical image enlarged and projected onto the projection surface. The focus regulator adjusts the focus of the optical image by changing the interval between the first and second lens units.  
         [0008]     A conventional focus regulator includes a controller protruding outside of a main body of the projection apparatus for easy controlling by a user, and a power transmission unit for transmitting power from the controller to the first lens unit. Operation of the focus regulator having the above configuration is started by a user rotating the controller. Then, the rotation of the controller is transmitted by the power transmission unit and causes a rotation of the first lens unit. The first lens unit moves in the direction of the optical axis of the optical image by the rotation. The movement of the first lens in the direction of the optical axis adjusts the interval between the first and second lens units, thereby adjusting the focus of the projected image. Additionally, the controller moves in the direction of the optical axis together with the first lens unit.  
         [0009]     However, when the controller moves in the direction of the optical axis, additional space inside the projection apparatus is necessary for accommodating the movement of the controller. In particular, because the controller is protruded outside of a main body of the projection apparatus for easy controlling by a user, a design for assuring the necessary space becomes more difficult. Additionally, providing this space hinders minimization of the projection apparatus.  
         [0010]     In particular, as the demand for a portable projection apparatus increases, developing a focus regulator having a simple structure and being advantageous to the minimization of the apparatus also becomes necessary.  
         [0011]     Additionally, as the importance of the design for the projection apparatus grows, a mask, fixedly installed on a main body of the projection apparatus, is used for covering the front of the main body. However, when the focus regulator described above is used, designing the mask is difficult as it should not restrict movement of the controller back and forth.  
         [0012]     Accordingly, a need exists for an improved projection apparatus having a focus regulator while minimizing the size of the projection apparatus.  
       SUMMARY OF THE INVENTION  
       [0013]     An object of the present invention is to provide a focus regulator that minimizes the size of a projection apparatus and a projection apparatus having the same.  
         [0014]     Additionally, another object of the present invention is to provide a focus regulator that simplifies the product design and a projection apparatus having the same.  
         [0015]     According to one aspect of the present invention, a focus regulator includes a controller rotatably installed on a main body that is limited to movement in the direction of the optical axis (OX), and a focus lens unit affixed with a projection lens unit of the main body that are movable in the direction of the optical axis by rotating them together with the controller.  
         [0016]     According to one exemplary embodiment of the present invention, the controller includes a ring-shaped body having an inner portion in which one end of the focusing lens unit is inserted, and at least one power transmission rib elongated and protruding from the body in the direction of the focus lens unit. Additionally, the focus lens unit includes a focus ring affixed to the power transmission rib in a manner that transmits rotary power. A focus lens barrel has at least one lens therein and fixes the focus ring. Additionally, a plurality of protrusions are formed at a certain interval on the outer circumference of the focus ring, and the power transmission rib is inserted between the protrusions. With this configuration, the controller is affixed with the focus lens unit, such that the focus lens unit moves in the direction of the optical axis (OX).  
         [0017]     Preferably, the focus lens unit is affixed to the projection lens unit using screws. Additionally, the main body has a base supporting the projection lens unit, a cover installed on the base that has an opening for inserting one end of the controller, and a mask installed on the cover to cover the opening-sided surface of the cover and that has an opening for inserting the other end of the controller. The movement of the controller in the direction of the optical axis (OX) is limited by means of the cover and the mask.  
         [0018]     An object of the present invention may also be achieved by a projection apparatus having a main body, and an illuminating optical system formed on the main body for generating and emitting light. An image formation unit formed on the main body for converts the light emitted by the illuminating optical system into an optical image. A projection lens unit receives the optical image converted by the image formation unit. A focus lens unit is movably affixed to the projection lens unit in the direction of the optical axis (OX). A controller rotatably installed on the main body is limited to movement in the direction of the optical axis (OX) for transmitting rotary power to the focus lens unit.  
         [0019]     Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     The above aspects and features of the present invention will be more apparent by describing certain exemplary embodiments of the present invention with reference to the accompanying drawings, in which:  
         [0021]      FIG. 1  is an exploded perspective view of a projection apparatus according to an exemplary embodiment of the present invention;  
         [0022]      FIG. 2  is a schematic diagram showing the operation of the projection apparatus of  FIG. 1 ;  
         [0023]      FIG. 3  is a further exploded perspective view of the projection apparatus of  FIG. 1 ; and  
         [0024]      FIGS. 4A and 4B  are elevational views in cross section according to line IV-IV of  FIG. 3  illustrating the operation of the projection apparatus of an exemplary embodiment of the present invention. 
     
    
       [0025]     Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures.  
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0026]     Certain exemplary embodiments of the present invention are described in greater detail with reference to the accompanying drawings.  
         [0027]     Referring to  FIGS. 1 and 2 , the projection apparatus according to one exemplary embodiment of the present invention includes a main body  10 , an illuminating optical system  30 , an image formation unit  50 , a projection lens unit  70 , and a focus regulator  100 .  
         [0028]     The main body  10  includes a base  12 , a cover  14 , a mask  16 , and a case  18 .  
         [0029]     The base  12  forms the bottom plane of the projection apparatus and supports the illuminating optical system  30 , image formation unit  50 , projection lens unit  70  and focus regulator  100 .  
         [0030]     The cover  14  is affixed to the base  12  for covering each part. An opening  15  is formed in the front of the cover  14  for passing the focus regulator  100  therethrough when it advances to adjust the focus.  
         [0031]     The mask  16  is preferably fixed using screws or the like at both sides of the cover  14  to cover both sides and the front of the cover  14 . An opening  17  corresponding to the opening  15  at the front of the cover  14  is formed at the front of the mask. The focus regulator  100  passes through the opening  17  in addition to the opening  15  formed in the cover  14  when the focus regulator advances. As illustrated in  FIG. 2 , a controller  140  of the focus regulator  100  is rotatably formed between the mask  16  and the cover  14 . Details of the focus regulator are described below.  
         [0032]     The case  18  houses the above parts and is fixed to the base  12 , preferably using screws or the like. The case  18  forms a module for the parts and may be omitted when each part is fixed to the base  12 .  
         [0033]     The illuminating optical system  30  includes a light source  32 , a collimating lens  34 , a dichroic filter  36 , and a relay lens unit  38 .  
         [0034]     The light source  32  includes a first light source  32   a  for irradiating blue and red light, and a second light source  32   b  for generating green light. A light emitting diode (LED) light source is preferably used as the first and second light sources  32   a  and  32   b  for minimizing the projection apparatus, but a halogen lamp, an ultra-high performance (UHP) lamp, or the like may also be used.  
         [0035]     The collimating lens  34  converts the light emitted from the first and second light sources  32   a  and  32   b  into parallel light, as shown in  FIG. 2 .  
         [0036]     The light is permeated or reflected by means of the dichroic filter  36  according to its wavelength. That is, by means of the dichroic filter  36 , red and blue light are permeated and green light is reflected. Therefore, light emitted from the first light source  32   a  is permeated and incident on the relay lens unit  38 . Additionally, light projected from the second light source  32   b  is reflected and incident on the relay lens unit  38 .  
         [0037]     The relay lens unit  38  plays a role not only in uniformly standardizing the density of the light emitted from the dichroic filter, but also in collecting the light into a rectangular shape and emitting it to the image formation unit  50 .  
         [0038]     The image formation unit  50  converts incident light from the relay lens unit  38  into an image in accordance with an image signal. A CRT (Cathode Ray Tube), an LCD (Liquid Crystal Display), a DMD (Digital Micromirror Device), and the like may be used as the image formation unit  50 , and the DMD is currently widely used as an image formation unit. The DMD consists of a plurality of independently rotatable mirrors that selectively reflect light emitted from the relay lens unit  38  to the projection lens unit  70 , thereby forming an image.  
         [0039]     The projection lens unit  70  is mounted inside the case  18  and receives the incident optical image generated from the image formation unit  50 . A plurality of lenses are arranged inside the projection lens unit  70 , and enlarge the optical image and compensate for various aberrations in the optical image. A screw thread  70   a,  shown in  FIG. 3 , is formed inside the projection lens unit  70 .  
         [0040]     Referring to  FIG. 3 , the focus regulator  100  includes a focus lens unit  120  and a controller  140 .  
         [0041]     The focus lens unit  120  includes a focus lens barrel  122  and a focus ring  124 .  
         [0042]     A screw thread  122   a  corresponding to the screw thread  70   a  of the projection lens unit  70  is formed on the outer circumference of the focus lens barrel  122 . The focus lens barrel  122  is inserted inside of the projection lens unit  70  and affixed therein by means of the screw threads  70   a  and  122   a.  Therefore, when the focus lens barrel  122  rotates, it moves linearly from the projection lens unit  70  in the direction of the optical axis (OX). Alternatively to the combination of the focus lens barrel  122  and the projection lens unit  70  using the screw thread, other combination means, such as a cam protrusion or a cam groove, may be used if a rotation of the focus lens barrel  122  results in movement in the direction of the optical axis of an optical image. At least one lens is arranged inside the focus lens barrel  122 , and adjusting the focus of the image projected onto a projection surface may be achieved by adjusting the distance between the lens in the focus lens barrel  122  and the lens in the projection lens unit  70 .  
         [0043]     A portion of the focus lens barrel  122  is inserted into the focus ring  124 , and the focus ring  124  is fixed to the focus lens barrel  122  by fixing the inserted portion of the focus lens barrel  122  preferably using screws or the like. Additionally, at least one protrusion  126  is formed on the focus ring  124 .  
         [0044]     The controller  140  includes a ring-shaped body  142 , at least one power transmission rib  144  protruding from the body  142  in the direction of the focus ring  124 , and a ring-shaped supporting rib  146  formed on the ring-shaped body  142  and protruding from the body in the direction of the mask, which is in a direction substantially opposite to the at least one power transmission rib  144 .  
         [0045]     The ring-shaped body  142  has a small diameter opening  148  in a central portion for passing the focus ring  124  therethrough. Therefore, the focus ring  124  moves linearly in the direction of the optical axis by passing through the opening  148  in the focus ring  124 .  
         [0046]     The power transmission rib  144  is inserted between the protrusions  126 . Therefore, if the controller  140  rotates, the rotary power of the controller  140  is transmitted to the focus ring  124  through the power transmission rib  144  and the protrusions  126 . Additionally, by rotating the focus ring  124 , the focus lens barrel  122  moves linearly from the projection lens unit  70  in the direction of the optical axis. However, the movement of the controller  140  in the direction of the optical axis is limited because it is placed between the cover  14  and the mask  16 . Therefore, the focus ring  124  performs a sliding movement in the opening  148  of the controller  140  along the power transmission rib  144  in the direction of the optical axis. Likewise, the rotary power of the controller  140  may be transmitted to the focus lens unit  120  by the simple structure of the power transmission rib  144  and the protrusions  126 . This configuration has the benefit of minimizing the projection apparatus. In particular, because the focus ring  124  slides on the controller  140  while being inserted between the power transmission rib  144  and the protrusions  126 , the controller  140  hardly receives a force acting in the direction of the optical axis, and has limited movement in the direction of the optical axis by means of the cover  14  and the mask  16 . Therefore, additional space for the movement of the controller  144  is not necessary, which is thereby more advantageous in minimizing the size of projection apparatus.  
         [0047]     When the protrusions  126  are formed on the focus lens barrel  122 , the focus ring  124  may be omitted. Additionally, according to one exemplary embodiment of the present invention, the cover  14  and the mask  16  limit the movement of the controller  140  in the direction of the optical axis. Alternatively, the power transmission rib  144  of the controller  140  may be elongated and protruding from the projection lens unit  70  so that the projection lens unit  70  limits the movement of the power transmission rib  144  in the direction of the optical axis. For example, a groove and a protrusion are formed on the projection lens unit  70  respectively in the circumferential direction and at one end of the power transmission rib  144 , and the protrusion rotates while being inserted into the groove so that the movement of the controller  140  in the direction of the optical axis may be limited when hooked to the groove.  
         [0048]     Meanwhile, according to one exemplary embodiment of the present invention, the projection lens unit  70  is an exemplary frame affixed to the focus lens barrel  122  using screws. Alternatively, the frame may be formed as a separate part affixed with the main body  10 . Additionally, the power transmission rib  144  of the controller  140  may be rotatably formed while having limited movement in the direction of the optical axis by forming a groove on the frame and elongating the power transmission rib  144  relative to the frame.  
         [0049]     The supporting rib  146  is inserted in the opening  17  of the mask  16 , and rotatable while allowing limited movement of the controller  140  in the direction of the optical axis (OX).  
         [0050]     Hereafter, referring to  FIGS. 4A and 4B , operation according to one exemplary embodiment of the present invention is described.  
         [0051]     First, light generated by the illuminating optical system  30 , shown in  FIG. 2 , is converted to an optical image by the image formation unit  50 , shown in  FIG. 2 . Additionally, the optical image passes through the projection lens unit  70  and the focus regulator  100 , and is projected onto a screen. Additionally, a user adjusts the controller  140  to focus the image projected onto the screen.  
         [0052]     At this time, the user rotates the controller  140  protruding from the cover  14  and the mask  16 . By rotating the controller  140 , the power transmission rib  144  of the controller  140  transmits the power to the protrusions  126  of the focus ring  124  and rotates the focus ring  124 . Additionally, when the focus ring  124  rotates, the focus lens barrel  122  fixed to the focus ring  124  also rotates. Additionally, the focus lens barrel  122 , which is preferably affixed to the projection lens unit  70  using screws, moves linearly from the projection lens unit  70  in the direction of the optical axis (OX).  
         [0053]     At this time, because the movement of the controller  140  in the direction of the optical axis (OX) is limited by the mask  16  and the cover  14 , the focus ring  124  moves in the direction of the optical axis by sliding into the power transmission rib  144 . Likewise, minimizing the projection apparatus is possible by limiting the movement of the controller  140  in the direction of the optical axis (OX), and the design restrictions are reduced without limiting the shape of the mask  16 . Additionally, the focus lens barrel  122  and the focus ring  124  pass through the opening  148  of the controller  140 , shown in  FIG. 3 , and hole  15 ,  17  of the cover  14  and the mask  16 , shown in  FIG. 3 , when they move linearly.  
         [0054]     As described above, according to the present invention, a power transmission structure between the controller and the focus lens unit is simplified, which is advantageous in minimizing the size of the projection apparatus.  
         [0055]     In particular, the focus lens unit moves in the direction of the optical axis (OX) without movement of the controller in the direction of the optical axis (OX), which is more advantageous in minimizing the size of the projection apparatus. Additionally, design restrictions may be reduced because mounting an accessory, such as the mask, is made easy.  
         [0056]     The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teachings may be readily applied to other types of apparatuses. Also, the description of the exemplary 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.