Abstract:
A self-supporting stand for a thin display device is to be controlled so that the display device faces in a preset screen direction in a one-touch manner. A function of constantly recognizing the screen direction of the display device and detecting its own direction by detecting a resistance value of a resistance volume such as a variable resistor installed in an electric screen direction changing mechanism, and a control unit which reproduces a preset screen direction no matter in which direction the screen faces currently, are combined with each other.

Description:
CLAIM OF PRIORITY 
   The present application claims priority from Japanese application serial no. JP 2005-178713, filed on Jun. 20, 2005, the content of which is hereby incorporated by reference into this application. 
   BACKGROUND OF THE INVENTION 
   The present invention relates to an image display device and a stand for the image display device able to rotate a body of the image display device to change the direction of the screen. 
   A known image display device is equipped with a stand for rotatably holding a body of the image display device so that the direction of the screen can be set freely. According to this image display device, by rotating the body of the image display device so that the screen is positioned in front of a user who watches the screen, it is possible to enhance the degree of freedom with respect to the position of the user and installation of the image display device. An image display device has recently been becoming more and more popular wherein the rotational movement of the body of the image display device is controlled remotely using a remote controller. 
   The technique of remotely controlling the rotational movement of the image display device body with a remote controller is disclosed, for example, in Patent Literature 1 (Japanese Patent Laid-Open No. 2001-285755). 
   SUMMARY OF THE INVENTION 
   According to the technique disclosed in Patent Literature 1, the direction of a remote control is detected and the image display device body is moved rotationally so that the screen faces in the detected direction. However, there is the problem that the user must continue pushing a button of the remote controller until the direction of the remote control is detected. Further, in the case where a large number of users watch the screen, a certain position of a person who has operated the remote controller does not correspond to an optimum direction of the screen because the screen faces in the remote controller-operated direction. 
   The present invention has bee accomplished for solving the above-mentioned problems and it is an object of the invention to provide an image display device convenient for use and able to direct the screen in a direction desired by a user. 
   The image display device of the present invention is provided with a rotating mechanism which rotates the direction of a screen of the image display device and a detector which detects the angle of rotation made by the rotating mechanism. According to this construction, the direction of the screen of the image display device can be rotated quickly to a desired angle. 
   Thus, the image display device is convenient for use and can direct the screen in a direction desired by a user. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features, objects and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings wherein: 
       FIG. 1  is a perspective view showing an appearance of an image display device according to a first embodiment of the present invention; 
       FIG. 2  is a perspective view of a stand portion in a state in which a body of the image display device is removed from the image display device; 
       FIG. 3  is a diagram showing an internal structure of the stand portion; 
       FIG. 4  is a block diagram of the image display device; 
       FIG. 5  is a diagram explanatory of a method for setting a memory position 1; 
       FIG. 6  is a flow chart of a method for storing and setting a screen position; 
       FIG. 7  is a diagram explanatory of a method for setting a memory position 2; 
       FIG. 8  is a diagram explanatory of operation for rotating the position of the body of the image display device up to the memory position 1; 
       FIG. 9  is a flow chart of operation for rotating the position of the body of the image display device up to the memory position 1; 
       FIG. 10  is a diagram showing operation of an image display device according to a second embodiment of the present invention; 
       FIG. 11  is a flow chart of operation of the image display device of the second embodiment; and 
       FIG. 12  is a flow chart of operation of an image display device according to a third embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   With reference to the accompanying drawings, the present invention will be described hereinunder by way of a plasma display panel as an example which is one of image display devices. In all the drawings, components having common functions are identified by the same reference numerals, and, repeated explanations of components once described will be omitted to avoid complexity. 
   First Embodiment 
   In an image display device according to a first embodiment of the present invention, a resistance volume of for example a variable resistor is installed within a screen direction changing mechanism, and by detecting a resistance value of the variable resistor, the direction of the screen of the display device is recognized constantly. 
   First, a description will be given about the construction of the image display device. 
     FIG. 1  is a perspective view showing an appearance of the image display device embodying the present invention. The reference numeral  10  denotes a body of the image display device, numeral  14  denotes a stand, and numeral  15  denotes a body holding portion. The image display device body  10  is held by the stand  14  through the body holding portion  15 . The image display device body  10  includes an image display portion  11 , a frame  12 , a speaker  13 , and a back cover  16 . Electric circuits such as a power supply circuit and an image control circuit (not shown) are disposed in the interior of the image display device body  10 . 
     FIG. 2  is a perspective view of the stand portion in a state in which the image display device body  10  is removed from the image display device. The image display device body  10  is fixed to and held by an arm  15   a  of the body holding portion  15 . The body holding portion  15  is held rotatably with respect to the stand  14 . As the body holding portion  15  rotates, the image display device body  10  rotates as well. 
   Next, a description will be given about a rotating mechanism.  FIG. 3  illustrates an internal structure of the stand  14 . The numeral  17  denotes a motor, which is connected to an angle detecting gear  21  via gear trains  181 ,  182 ,  183 , and  184 . The angle detecting gear  21  is fixed to the body holding portion  15 . When the motor  17  is rotated, its rotational force causes the angle detecting gear  21  to rotate via gear trains  181 ,  182 ,  183 , and  184 . The body holding portion  15  is adapted to rotate with rotation of the angle detecting gear  21 . Numeral  19  denotes a potentiometer and numeral  20  denotes a movable gear. A gear is provided in a sensor portion of the potentiometer  19  and a gear is also provided on an inner surface of the movable gear  20 , both gears being in mesh with each other. The movable gear  20  is fixed to the body holding portion  15  and is adapted to rotate with rotation of the body holding portion  15 , causing the sensor portion of the potentiometer  19  to rotate. The potentiometer  19  is provided in the interior thereof with a variable resistor to convert a rotational angle of the sensor portion into an electric signal. The rotational angle of the body holding portion  15  can be detected by monitoring the output of the potentiometer  19  and hence it is possible to detect in which direction the image display portion  11  of the image display device body  10  faces. Numeral  23  denotes a connector, which is connected to both motor  17  and potentiometer  19  by wiring. 
     FIG. 4  is a block diagram of part of the image display device embodying the present invention. As described earlier, numerals  14 ,  17 ,  19 , and  23 , denote a stand, a motor, a potentiometer, and a connector, respectively. The image display device body  10  includes a connector  24 , a power supply  25  for the motor, a microcomputer  26 , a memory  27 , and a remote controller photoreceiver  28 . Numeral  29  denotes a remote controller. In addition to these components, electric circuits such as a control circuit and a power supply circuit are installed in the image display device body  10 , but their illustrations are omitted to simplify the explanation. The image display device body  10  and the stand  14  are electrically connected together by the connectors  23  and  24 . 
   A brief description will now be given about the operation. When a button of the remote controller  29  is pushed, a control signal is transmitted from the remote controller photoreceiver  28  to the microcomputer  26 . The microcomputer  26  transmits electric power from the motor power supply  25  to the motor  17  via the connectors  23  and  24 , causing the image display device body  10  to rotate. At this time, the microcomputer  26  reads via the connectors  23  and  24  a screen position signal provided from the potentiometer  19  and detects the angle (screen position) of the image display device body  10 . Usually, a limitation is placed such that the rotational range of the image display device body  10  is up to 20° to the right and left. This is because if the rotational range is set large, the image display device body may collide with a wall or the like located near the installed place of the image display device. 
   Next, a description will be given about a method for setting a first position (memory position 1) of the image display device body  10 .  FIG. 5  is a diagram explanatory of a method for setting the memory position 1. Numeral  29  denotes a remote controller, numeral  301  denotes a right rotation button, numeral  302  denotes a position memory button, and numeral  311  denotes a memory position 1 button. Numeral  101  indicates the present position of the image display device body  10  and numeral  102  indicates a desired screen direction of the image display device body  10 . 
     FIG. 6  is a flow chart of a method for storing and setting a screen position. With reference to  FIGS. 5 and 6 , a description will be given below about a method for setting the screen memory position 1. 
   First (S 61 ), the right rotation button  301  of the remote controller  29  is pushed (S 62 ). The resulting signal is received by the remote controller photoreceiver  28 , which in turn transmits the signal to the microcomputer  26 . The microcomputer  26  supplies electric power from the motor power supply  25  to the motor  17  installed within the stand  14 , causing the motor  17  to rotate and thereby causing the gear trains  181 ,  182 ,  183 , and  184  to rotate, whereby the angle detecting gear  21  rotates. As a result, the image display device body  10  rotates in the direction of arrow (S 63 ). The right rotation button  301  is kept pushed until the image display device body  101  arrives at the position  101  (S 64 →S 63  is repeated). Upon arrival of the image display device body at the position  101  (S 64 →S 65 ), the right rotation button  301  is released (S 65 ), whereby the supply of electric power from the motor power supply  25  to the motor  17  stops and the image display device body  10  stops at the position  102 . In this state, the position memory button  302  of the remote controller  29  is pushed and subsequently the memory position 1 button  311  is pushed (S 66 ), whereby the microcomputer  26  reads a screen position signal from the potentiometer  19  (S 67 ), stores the screen position as the memory position 1 in the memory  27  (S 68 ) and ends the screen position storing and setting process (S 69 ). 
   Next, a description will be given about a method for setting a second position (memory position 2) of the image display device body  10 .  FIG. 7  is a diagram explanatory of a method for setting the memory position 2. Numeral  303  denotes a left rotation button and numeral  312  denotes a memory position 2 button. Numeral  101  indicates the present position of the image display device body  10  and numeral  103  indicates a desired screen direction of the image display device body  10 . 
   As in the above method for setting the memory position 1, when the left rotation button  303  of the remote controller  29  is pushed, the image display device body  10  rotates in the direction of arrow, and the left rotation button  303  is released upon arrival of the image display device body  10  at the position of  103 . Then, by pushing the position memory button  302  and subsequently pushing the memory position 2 button  312 , the position of  103  is stored as a memory position 2 in the memory  27 . 
   In the image display device embodying the present invention, as described above, the user sets the position of the image display device body  10  to a desired position by pushing the right rotation button  301  and the left rotation button  303  of the remote controller  29 , and thereafter the set position is stored. Thus, the position can be set freely within the rotational range of the image display device body  10 . 
   A description will now be given about a method for making the position of the image display device body  10  coincident with the memory position 1.  FIG. 8  is a diagram explanatory of operation for rotating the position of the image display device body  10  up to the memory position 1. Numeral  103  indicates the present position (memory position 2) of the image display device body  10  and numeral  102  indicates the memory position 2.  FIG. 9  is a flow chart of operation for rotating the position of the image display device body  10  up to the memory position 1. 
   First (S 91 ), the memory position 1 of the remote controller  29  is pushed (S 92 ). A control signal provided from the remote controller  29  is received by the remote controller photoreceiver  28 , which in turn transmits the signal to the microcomputer  26 . The microcomputer  26  reads position information for the memory position 1 from the memory  27  (S 93 ). Next, the microcomputer  26  reads position information from the potentiometer  19  in order to detect the present direction in which the image display device body  10  faces (S 94 ). Then, the microcomputer  26  makes comparison between the position information read from the memory  27  and corresponding to the memory position 1 and the position information in the present direction in which the image display device body  10  faces (S 95 ). If both are different, electric power is fed to the motor  17  from the motor power supply  25  to rotate the image display device body  10  so that the direction in which the image display device body  10  faces coincides with that of the memory position 1 (S 96 ). These operations are repeated and when the position information provided from the potentiometer  19  becomes coincident with the position information corresponding to the memory position 1, that is, when the position of the image display device body  10  rotates up to the position  102 , the supply of electric power to the motor  17  is stopped to end the processing (S 97 ). 
   Thus, by such a simple operation as merely pushing the buttons  311  and  312  of the remote controller  29 , it is possible to change the direction of the screen of the image display device body  10  to a stored position, with the result that the image display device becomes more convenient for use. 
   Although the number of memory positions in the above first embodiment is two, no limitation is made thereto. There may be three or more such memory positions. Also for the operating buttons of the remote controller  29 , each button possesses one function in the above first embodiment, but no limitation is made thereto. A single button may be used in common to two or more functions. 
   Second Embodiment 
   The structure and configuration of an image display device according to a second embodiment of the present invention are the same as in the first embodiment and therefore an explanation thereof will here be omitted. 
   The operation of the image display device of this second embodiment will be described with reference to  FIG. 10  which illustrates the same operation. As shown in  FIG. 10 , the direction of the image display device body  10  can be set in five stages which are a front direction ( 106 ), further, with respect to the front direction, rightward 10° rotation ( 105 ), rightward 20° rotation ( 104 ), leftward 10° rotation ( 107 ), and leftward 20° rotation ( 108 ). In this case, it is assumed that the positions of  104 ,  105 ,  106 ,  107 , and  108 , are positions 1, 2, 3, 4, and 5, respectively, and that the rotational range of the image display device body  10  is from leftward 20° to rightward 20°. Position information pieces at the respective positions of the image display device body  10 , which are provided from the potentiometer  19 , are stored beforehand in the memory  27 . 
     FIG. 11  shows an operation flow of the image display device of the second embodiment. The operation of the image display device performed when pushing the right rotation button  322  of the remote controller  29  will be described below as an example in a state in which the image display device body  10  currently lies at position 2 ( 105 ). 
   First (S 111 ), when the right rotation button  322  of the remote controller  29  is pushed (S 112 ), position information provided from the potentiometer  19  is read and it is detected in which position the image display device body  10  lies at present. In this case, since the image display device body  10  lies at position 2 ( 105 ), N=2 (S 113 ). A check is made to see if the button pushed in S 114  is the right rotation button  322 . Since in this case the button in question is the right rotation button  322 , the processing flow advances to S 115 , in which P=1 (=N−1). In S 116 , a check is made to see if N≠1. Since N=2, the processing flow advances to S 117 , in which the image display device body  10  is rotated into position P (=1), followed by ending of the process (S 121 ). That is, when the right rotation button  322  is pushed in the state of position 2 ( 105 ), the image display device  10  rotates 10° rightward into position 1 ( 104 ). From this state (S 111 ), when the right rotation button  322  is further pushed (S 112 ), as in the above processing, N=1 in S 113 , and then in S 115  from S 114 , P=0. Since N=0 in S 116 , the processing flow advances to S 121  to end the processing without rotation of the image display device body  10 . That is, a control is made lest the position of the image display device body  10  should exceed the rotatable range. 
   From this state, when the left rotation button  321  of the remote controller  29  is pushed, the processing advances to S 114  in the same manner as is the case with the right rotation button  322  being pushed. N=1 is detected in S 113 , and then the processing flow advances from S 114  to S 118 . Since the pushed button is the left rotation button  321 , the processing flow advances from S 118  to S 119 , in which P=2 (=N+1). Then, since N≠5 in S 120 , the processing flow advances to S 117 , in which the image display device body  10  is rotated into position P (=2), and then the processing ends (S 121 ). The reason why N≠5 is checked in S 120  is that it is intended to prevent the position of the image display device body  10  from exceeding the rotatable range. That is, when the left rotation button  321  is pushed, the image display device body  10  rotates 10° leftward within a range not exceeding the rotatable range. 
   Thus, by such a simple operation as merely pushing the buttons  321  and  322  of the remote controller  29 , it is possible to change the direction of the screen of the image display device body  10 , so that the device becomes easier to use as in the first embodiment. 
   Although in this second embodiment it has been described that the rotational angle in a single operation is 10° and that the rotatable range is from 20° leftward to 20° rightward, no limitation is made thereto. Further, although the number of memory positions is two, no limitation is made thereto, either. 
   Third Embodiment 
   In the previous first and second embodiments an angle desired by the user is stored and the screen direction is rotated to the stored angle position in a simple manner using a remote controller. However, it is presumed that the setting of angle on the user side is performed in increments of about 10° as in the second embodiment for example. In such a case, it may be necessary to finely adjust the screen angle after rotation. 
   In this third embodiment, therefore, a description will be given below about the mode of finely adjusting the screen angle after rotation with use of a simple method. 
     FIG. 12  shows an operation flow of an image display device according to this third embodiment. 
   Reference will be made below to an example of operation performed when the left rotation button  321  of the remote controller  29  is pushed long in a state in which the image display device body  10  currently lies at position  2  ( 105 ). By pushing the remote controller button long as referred to herein is meant to push the button three seconds or longer for example. 
   First (S 211 ), when the left rotation button  321  of the remote controller  29  is pushed (S 212 ), position information provided from the potentiometer  19  is read and it is detected at which position the image display device body  10  lies at present. In this case, N is equal to 2 (N=2) because the image display device body  10  lies at position 2 ( 105 ) (S 213 ). A check is made to see if the button was pushed long in S 214 . Since the answer is affirmative in this case, the processing flow advances to S 215 , in which the angle is adjusted at predetermined angular intervals of, say, 1° and the processing ends (S 221 ). The processing to be performed when the button is not pushed long is the same as in the second embodiment and therefore an explanation thereof is here omitted. Also for the right rotation button  322 , the screen angle can be adjusted by the same operation. 
   Thus, fine adjustment is made by pushing the remote controller button long, while rotation to a memory position is performed by pushing the button short. With such a simple operation, the screen direction of the image display device body  10  can be rotated to a desired direction and thus the image display device becomes easier to use. 
   Although in the above third embodiment movement to a stored angle and fine adjustment of the angle are switched from one to the other by changing the operation time of the same button, no limitation is made thereto. A button for fine adjustment and a button for movement to a stored angle may be provided. 
   Although the present invention relates to an image display device, the invention may also be applied to audio devices such as speakers and general electric devices. 
   While we have shown and described several embodiments in accordance with our invention, it should be understood that disclosed embodiments are susceptible to changes and modifications without departing from the scope of the invention. Therefore, we do not intend to be bound by the details shown and described herein but intend to cover all such changes and modifications as fall within the ambit of the appended claims.