Abstract:
A coordinates detection apparatus comprises two optical units each having a light emitter, a diffusion lens, a read lens, and a light-receiver. The optical units are provided at different positions on the border of a display surface. The light-emitter and light-receiver in each optical unit are so located that their optic axes are coincident. A recursive reflection section reflects the light emitted from the light-emitter and diffused by the diffusion lens in a fan form towards the light-emitter. The coordinates of a point specified on the display surface are detected by focusing the light reflected on the reflection section with the read lens, receiving the reflected light with the light-receiver, and determining the position where reception of the light is hindered.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a coordinates detection apparatus which detects coordinates of a point specified on the surface of a panel such as a touch panel. 
     BACKGROUND OF THE INVENTION 
     There have been known various types of coordinates detection apparatus used, for instance, for touch panel. For example, such an apparatus is disclosed in Japanese Patent Laid-Open Publication No. HEI 9-91094. In the apparatus disclosed in this application, two optical units each having a light-emitter and a light-receiver are provided at different positions on the border of the surface of the touch panel, and further a reflection section which reflects a light emitted from the light-emitter in the direction from where the light was emitted on the border of the surface. 
     As mentioned above, the conventional coordinates detection apparatus has two optical units and a reflection section. Light from the light-emitter is projected parallel to the surface of the panel in the form of a fan. The light is reflected by the reflection section in the direction from where the light was emitted, that is, towards the light-emitter. The reflected light is received by the light-receiver. When a user touches a point on the surface of the panel, with a finger or the like, then the light passing through this point is interrupted. Therefore, there occur places in each of the light-receivers which do not receive the reflected light. Accordingly, from the position of such places in the light-receivers it is possible to calculate the coordinates of the point where the finger of the like had touched the surface of the panel. 
     The coordinates detection apparatus disclosed in Japanese Patent Laid-Open Publication No. HEI 9-91094 has following disadvantages. The optic axis of the light-emitter and the light-receiver have an angle between them. Therefore, the light-emitter and light-receiver must be located with a specified space therebetween. This makes it difficult to reduce a size of the optical unit which comprises the light-emitter and the light-receiver. 
     Furthermore, a lens is provided in front of the light-receiver in the path of the reflected light. This lens forms an image on the light-receiver. Because the optic axis of the light-emitter and the light-receiver have an angle between them, there is a problem that, the center of the light projected from the light-emitter and diffused in the form of a fan is offset from the center of the lens provided in front of the light-receiver. Resultantly, there is a disadvantage that the precision in detection of the coordinates is low. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a coordinates detection apparatus which makes it possible to reduce a size of the optical unit used therein. 
     It is another object of the present invention to provide a coordinates detection apparatus which insures high precision in detection of the coordinates. 
     According to the coordinates detection apparatus of one aspect of the present invention, optic axis of the light-emitter and the light-receiver are coincident to each other. Therefore, the light-emitter and light-receiver can be located at positions close to each other. 
     Further, the half mirror is located on the optic axes of the light-emitter and light-receiver. Therefore, the light-emitter and light-receiver can be located at any positions by making use of this half mirror. 
     Further, the light-emitter, diffusion lens, read lens, and half mirror are mounted in one frame. Therefore, the size of the optical unit can be reduced. 
     Further, a central point of emission of light diffused by the lens and a principal point of the read lens are coincident to each other. 
     Further, the optical unit has an optical adjustment mechanism for the light-emitter and light-receiver. Therefore, the light-emitter and light-receiver in each optical unit can be adjusted discretely. 
     Further, the optical unit is located at a position close to the display surface. Therefore, optic axes of the light-emitter and the light-receiver can be located at a position close to the display surface. 
     Further, there is provided a mounting position adjustment mechanism for adjusting a mounting position of the optical unit. Therefore, precision in detection of the coordinates can be improved by adjusting a mounting position of the optical unit. 
     Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a general flat view showing basic configuration of a first embodiment of the present invention; 
     FIG. 2 is a longitudinal cross-sectional view showing internal structure of the optical unit; 
     FIG. 3 is a bottom view showing internal structure of the optical unit; 
     FIG. 4 is a side view showing the optical unit; 
     FIG. 5 is a front view showing a mounting structure of the optical unit; 
     FIG. 6 is a flat view showing a mounting structure of the optical unit; and 
     FIG. 7 is a side view showing a mounting structure of the optical unit. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A first embodiment of the present invention is described below. FIG. 1 is a general flat view showing basic configuration of the present invention. A panel face  1   a  which is a display surface is provided in a touch panel  1 . The panel face  1   a  has a rectangular shape. Two optical units  2  are located at two corners of the border of the panel face  1   a . Further, a reflection section  3  is located along three borders. That is, the reflection section  3  is not provided along the border that has the optical units  2  at its ends. A recursive reflection sheet with trihedral cubes provided at a high density therein is provided in the reflection section. Signals from the two optical units  2  are input into a computing section  4 . This computing section  4  is connected to a personal computer  6  through an interface section  5 . 
     A frame  7  is provided around the panel face  1   a  (see FIG.  5 ). The optical units  2 , reflection section  3 , and a casing covering the reflection section  3  are mounted on this frame  7 . 
     FIG. 2 is a longitudinal front view showing an internal structure of the optical unit  2 . FIG. 3 is a bottom view showing the optical unit. FIG. 4 is a side view showing the optical unit. In the optical unit  2 , a frame  9 , a first holding plate  10 , a second holding plate  11 , circuit boards  12 ,  13 , a rear plate  14 , and other components are provided. A light-emitter  15 , a diffusion lens  16 , a half mirror  17 , protection glass sheet  18 , a read lens  19 , and a CCD  20  which is a light-receiver are mounted on the frame  9 . 
     A laser beam is projected from the light-emitter  15  under controls by the computing section  4 , and the laser beam projected from the light-emitter  15  is diffused by the diffusion lens  16  in parallel to the panel face  1   a  and in a fan form (having a central angle of 90 degrees herein), and hits the half mirror  17 . A half quantity of the laser beam which hits the half mirror  17  passes through the half mirror  17 , and a remaining half quantity of the laser beam is reflected in a direction to the rear plate  14 . The laser beam having passed through the half mirror  17  further passes through the protection glass sheet  18 , progresses straightly, hits the reflection section  3 , and then is reflected in a direction to the light-emitter. The laser beam which is reflected on the reflection section  3  and returns in the direction to the light-emitter passes through the protection glass sheet  18 , and hits the half mirror  17 . A half quantity of the laser beam which hits the half mirror  17  transmits the half mirror  17  and progresses straightly in a direction to the light-emitter  15 , while a remaining half quantity of the laser beam is reflected to the read lens  19 , focused by the read lens  19  onto the CCD  20 , and is received by the CCD  20 . 
     The protection glass sheet  18  is provided to prevent foreign materials such as dusts or a finger of a touch panel user from entering the frame  9 . This protection glass sheet  18  is inclined by 6 degrees against the vertical direction to the panel face  1   a  so that, even if a laser beam progressing to the reflection section  3  is reflected, when passing through the protection glass sheet  18 , on a surface of this protection glass sheet  18 , the reflected light is reflected in a direction where the reflected light is not received by the CCD  20 . 
     Optic axes of the light-emitter  15  and the CCD  20  are coincident to each other and the half mirror  17  is located on these optic axes. Further a central point “A” of light emission of the laser beam diffused by the diffusion lens  16  and a principal point “B” of the read lens  19  are coincident to each other. 
     The circuit board  12  which controls and drives the light-emitter  15  is connected to the light-emitter  15 , while the circuit board  12  which controls and drives the CCD  20  is connected to the CCD  20 . The circuit board  12  is fixed to a second holding plate  11 , and this second holding plate  11  is fixed with a screw  21  to a first holding plate  10 . Further a plate spring  22  is tightened and fixed with the screw  21 , and with the plate spring  22 , the light-emitter  15  is pressed to and positioned against the second holding plate  11 . 
     A pair of lengthy holes  11   a  for adjustment are formed on the second holding plate  11 , and further round holes  10   a  are formed at positions opposite to the lengthy holes  11   a  for adjustment provided on the first holding plate  10  (Refer to FIG.  4 ). When the screw  21  is loosened, an eccentric pin (not shown) is inserted through the round hole  10   a  as well as through the lengthy hole  11   a , and the second holding plate  11  is slid or the eccentric pin is rotated, the second holding plate  11  can be adjusted in the vertical direction (in the direction indicated by the arrow X) and in the horizontal direction (in the direction indicated by the arrow Y). By adjusting a position of the second holding plate  11  in the vertical direction or in the horizontal direction, it is possible to adjust the position of the light-emitter  15  in the vertical direction as well as in the horizontal direction, and the lengthy hole  11   a  for adjustment and the round hole  10   a  are part of an optical adjustment mechanism of the light-emitter  15 . An escape hole  12   a , into which the eccentric hole is inserted, is formed on the circuit board  12 . 
     Two round holes  10   b ,  10   c , into which a screw (not shown) for fixing the first holding plate  10  to the frame  9  is inserted, are formed on the first holding plate  10  (Refer to FIG.  3 ). One round hole  10   b  is formed with the same diameter as that of the screw, while the other round hole  10   c  is formed with a diameter larger than that of the screw. Further a lengthy hole  10   d  for adjustment is formed on the first holding plate  10 , and a round hole  9   a  is formed at a position opposite to the lengthy hole  10   d  for adjustment on the frame  9 . When the screw jointing the first holding plate  10  to the frame  9  is loosened, an eccentric pin (not shown) is inserted into the round hole  9   a  and lengthy hole  10   d  for adjustment, and the pin is rotated, the first holding plate  10  is rotated around the screw inserted into the round hole  10   b , thus the position of the light-emitter  15  being adjusted back and forth (in the direction indicated by the arrow Z). By adjusting the position of the first holding plate  10  back and forth, a position of the light-emitter  15  can be adjusted back and forth, and the round holes  10   b ,  10   c , lengthy hole  10   d  for adjustment, and round hole  9   a  are part of an optical adjustment mechanism of the light-emitter  15 . 
     The circuit board  13  is fixed with a screw  23  to the frame  9 , and the CCD  20  is fixed to the circuit board  13 . Further a pair of length holes  13   a  for adjustment are formed on the circuit board  13 , and round holes  9   b  are formed at positions opposite to the lengthy holes  13   a  on the frame  9  (Refer to FIG.  3 ). When the screw  23  is loosened, an eccentric pin (not shown) is inserted into the round hole  9   b  and lengthy hole  13   a  for adjustment, the circuit board  13  is slid, or the eccentric pin is rotated, the circuit board  13  can be adjusted back and forth (in the direction indicated by the arrow Z) and in the horizontal direction (in the direction indicated by the arrow Y). By adjusting the circuit board  13  back and forth or right and left, a position of the CCD  20  can be adjusted back and forth or right and left. The lengthy hole  13   a  for adjustment and round hole  13   a  are part of an optical adjustment mechanism of the CCD  20 . 
     FIG.  5  through FIG. 7 shows a structure for mounting the optical unit  2  onto the frame  7  and a mounting position adjustment mechanism, and FIG. 5 is a front view, FIG. 6 is a flat view, and FIG. 7 is a side view. A pair of projections  24  are formed on an external peripheral surface of the frame  9  with an L-shaped bracket  25  fixed with a screw to each of the projections  24 , and a -shaped bracket  27  is fixed to each of the brackets  25 . 
     On the bracket  25 , a half-blanked projection  29  is formed at a position opposite a central point “A” of emission of the laser beam diffused by the diffusion lens  16  when the bracket  25  is viewed from the front side, and an engagement hole  30  in which the projection  29  is engaged in is formed on the bracket  27 . 
     On two side faces of the bracket  27  fixed onto the bracket  25  with screws, a lengthy hole (not shown) and a lengthy hole  27   a  for adjustment, into which the screw  28  is inserted, are formed, and round holes  25   a  are formed at positions opposite to the lengthy holes  27   a  on the bracket  25  (see FIG.  5 ). When the screw  28  is loosened and an eccentric pin (not shown) is inserted into the round hole  25   a  and the lengthy hole  27   a  for adjustment to rotate the bracket  25 , the frame  9  and bracket  25  rotate around the projection  29  engaged in the engagement hole  30  in a direction indicated by the arrow a. With this operation, a mounting position of the optical unit  2  can be adjusted. The lengthy hole  27   a  and round hole  25   a  are part of the mounting position adjustment mechanism for the optical unit  2 . 
     A fixing plate  31  is fixed with a screw  32  to the bracket  27 . A pair of lengthy holes  31   a , a lengthy hole  31   b  positioned on the optic axis, and a pair of lengthy holes  31   c  for adjustment are formed on the fixing plate  31 . The screw  32  for jointing the fixing plate  31  to the bracket  27  is passed through the lengthy hole  31   a , a half-blanked projection  33  formed on the bracket  27  is engaged in the lengthy hole  31   b , and round holes  27   b  are formed at positions opposite to the lengthy holes  31   c  on the bracket  27 . When the screw  32  is loosened and an eccentric pin (not shown) is inserted into the round hole  27   b  and lengthy hole  31   c  for adjustment to rotate the bracket  27 , the bracket  27  can be slid in a direction where the projection  33  slides along the lengthy hole  31   b  (in the direction indicated by the arrow b). With this operation, a mounting position of the optical unit  2  can be adjusted. Therefore the lengthy hole  31   c  for adjustment and round hole  27   b  are part of a mounting position adjustment mechanism of the optical unit  2 . 
     Joint of the fixing plate  31  to the frame  7  is executed by engaging a half-blanked projection  34  formed on the fixing plate  31  in a hole section (not shown) of the frame  7  and tightening the screw  35 . Further the optical unit  2  is located at a position where optic axes of the light-emitter  15  and CCD  20  are close to a surface of the panel face  1   a.    
     With the configuration as described above, a laser beam projected from the light-emitter  15  is diffused by the diffusion lens  16 , the diffused laser beam passes through the half mirror  17  and protection glass sheet  18 , progresses to the reflection section  3 , is reflected on the reflection section  3 , progresses on the same optic axis, and returns to the optical unit  2 . The light beam then returns to the optical unit  2 , passes through the protection glass sheet  18 , and is reflected by the half mirror  17  to the side of CCD  15 . The reflected laser beam is focused by the read lens  19  onto the CCD  20 , and is detected by the CCD  20 . 
     When a position on the panel  1   a  is touched, for instance, by a finger in this state, a laser beam passing through the position is intercepted by the laser beam, and a point where the reflected light is not received is generated in the CCD  20  in each of the optical units  2 . By computing the points from a result of detection with the detected CCD  20  (the computing is executed based on a principle of triangulation), the coordinates of the point touched with a finger or the like can be detected. 
     In the coordinates detection apparatus according to the present invention, optic axes of the light-emitter  15  and the CCD  20  are coincident to each other and the half mirror  17  is located on these optic axes. Because of this configuration, the light-emitter  15  and CCD  20  can be located at any positions close to each other, which enables size reduction of the optical unit  2  and improvement in the designing freedom. 
     Further a central point of emission of the light diffused by the diffusion lens  16  and a principal point “B” are coincident to each other, so that precision in detection of the coordinates can be improved. In addition, as the optical unit  2  is located at a position close to the panel face  1   a , a optic axis of the light-emitter  15  and that of the CCD  20  can be located at positions close to a surface of the panel face  1   a , which insures higher precision in detection of the coordinates. Further, as the optical unit  2  is located at a position close to the panel face  1   a , a height and a size of the touch panel  1  become smaller, which enables size reduction of the touch panel  1 . 
     The light-emitter  15 , diffusion lens  16 , read lens  19 , and half mirror  17  are mounted to the frame  9 , which enables further size reduction of the optical unit  2 . In addition, a number of components used for assembly of the optical unit  2  becomes smaller, which results in cost reduction. 
     The optical unit  2  has an optical adjustment mechanism for the light-emitter  15  comprising the lengthy holes  11   a  for adjustment and round holes  10   a , an optical adjustment mechanism for the light-emitter  15  comprising the round holes  10   b ,  10   c , lengthy hole  10   d  for adjustment, and round hole  9   a , and an optical adjustment mechanism for the CCD  20  comprising the lengthy holes  13   a  for adjustment and the round hole  9   b , so that optical adjustment for the light-emitter  15  and CCD  20  can be executed for each optical unit  2  discretely, and in addition optical adjustment can be performed before the optical unit  2  is assembled to the touch panel  1 , which insures excellent performance of the optical unit  2 . 
     A mounting position of the optical unit attached to the frame  7  can be adjusted by a mounting position adjustment mechanism comprising the lengthy holes for adjustment and the round holes  25   a  and a mounting position adjustment mechanism comprising the lengthy holes  31   c  and round holes  27   b , and with this adjustment, precision in detection of the coordinates can be improved. 
     According to the coordinates detection apparatus of one aspect of the present invention, optic axis of the light-emitter and the light-receiver are coincident to each other. Therefore, the light-emitter and light-receiver can be located at positions close to each other. Accordingly, the size of the optical unit can be reduced considerably. 
     Further, the half mirror is located on the optic axes of the light-emitter and light-receiver. Therefore, the light-emitter and light-receiver can be located at any positions by making use of this half mirror. Accordingly, freedom in designing can be increased highly. 
     Further, the light-emitter, diffusion lens, read lens, and half mirror are mounted in one frame. Therefore, the size of the optical unit can be reduced. Furthermore, cost reduction can be achieved by reducing a number of components used for assembly of the optical unit. 
     Further, a central point of emission of light diffused by the lens and a principal point of the read lens are coincident to each other. Therefore, precision in detection of the coordinates can be improved. 
     Further, the optical unit has an optical adjustment mechanism for the light-emitter and light-receiver. Therefore, the light-emitter and light-receiver in each optical unit can be adjusted discretely. In addition, optical adjustment of the optical unit can be performed before the optical unit is assembled into a device such as a touch panel. This arrangement insures an excellent performance of the optical unit. 
     Further, the optical unit is located at a position close to the display surface. Therefore, optic axes of the light-emitter and the light-receiver can be located at a position close to the display surface. This insures higher precision in detection of the coordinates. 
     Further, there is provided a mounting position adjustment mechanism for adjusting a mounting position of the optical unit. Therefore, precision in detection of the coordinates can be improved by adjusting a mounting position of the optical unit. 
     The present document incorporates by reference the entire contents of Japanese priority document, JP 11-201572 filed in Japan on Jul. 15, 1999. 
     Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.