Abstract:
The present invention discloses an optical remote control system, and a method for controlling a light source of the system. The system includes: a light source including a plurality of lighting units, the light source generating at least one light beam; an image sensor receiving an image including the light beam; and a processor determining a number or positions of the lighting units which are activated according to an area of the light beam in the image.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The present invention relates to an optical remote control system and a light source control method therefor, in particular to such optical remote control system and light source control method which are capable of modulating a light source for better orientation. 
         [0003]    2. Description of Related Art 
         [0004]    Many current interactive video game systems provide users with joysticks or remote controllers so that the users can play the games by actions, e.g. to drive a race car, to swing a golf club, etc. Such joystick or remote controller typically includes a gyro, an accelerometer, or an image sensor. In a joystick or remote controller which employs the image sensor, the image sensor senses images and generates information for controlling the movement of a cursor or a pointer on a screen, or for selecting an icon to execute a corresponding function or program, etc. 
         [0005]      FIG. 1A  shows a schematic diagram illustrating the use of a joystick in a prior art interactive video game system. The orientation of the joystick  11  is identified according to the images captured by the image sensor  111 . That is, the positions of the light beams from the multiple lighting units  131  of the light source  13  in the images captured by the image sensor  111  are used to confirm the orientation of the joystick  11  such that, e.g., a cursor  141  on the display  14  is accurately moved from the left side to the right side. Referring to this figure, the light source  13  comprises six lighting units  131  which are all turned on to light during operation of the game system, to form one light spot in the image captured by the image sensor  111 . However, if the distance between the joystick  11  (or the image sensor  111 ) and the light source  13  is too short, the light beams from the multiple lighting units  131  form a bigger light spot in the image captured by the image sensor  111 , and the short distance may cause overexposure such that it is hard to recognize the light spot in the captured image. On the contrary, if the distance between the joystick  11  and the light source  13  is too far, the light spot formed by the light beams from the lighting units  131  in the image captured by the image sensor  111  is likely to be too small and hard to be recognized. Therefore, the distance between the conventional joystick  11  and the light source  13  needs to be kept within a proper workable range, otherwise the light spot in the captured image is oversize or undersize. 
         [0006]      FIGS. 1B-1C  show schematic diagrams illustrating the light spot in the image captured by the image sensor. Referring to  FIG. 1B , when the distance between the image sensor and the light source is L, the width of the visible region resulting from the visible angle  152  of the image sensor is W, and the light spot  151  in the image  15  covers four pixels. Referring to  FIG. 1C , when the distance between the image sensor and the light source is 2L, the width of the visible region resulting from the visible angle  152 ′ of the image sensor is 2 W, and the light spot  151 ′ in the image  15 ′ covers two pixels. If the recognizable range of the light spot is 2-4 pixels, then the light spot is not recognizable if it covers less than two pixels or more than four pixels. This means that the operating distance of the prior art is L−2L. If the operating distance is smaller than L or larger than 2L, the system cannot properly respond. 
         [0007]    The limited operating distance or operating range is disadvantageous; the light spot is smaller than the required minimum size and cannot be recognized when the distance is longer than the maximum operating distance, and the light spot image is larger than the required maximum size and cannot be recognized when the distance is shorter than the minimum operating distance. If the size of the light spot is enlarged to increase the maximum operating distance, the minimum operating distance is adversely affected. On the contrary, if the size of the light spot is decreased to shorten the minimum operating distance, the maximum operating distance of the light spot image is also shortened. 
         [0008]    In view of above, the present invention overcomes the foregoing drawbacks by providing an improved optical remote control system and a light source control method. The operating distance of the optical remote control system can be enlarged by adjusting the number and the positions of the lightened units of the light source for the orientation. The light spot becomes recognizable more accurately in a wider range, and the lighting units can be controlled in an optimal way to effectively save the power of the light source. 
       SUMMARY OF THE INVENTION 
       [0009]    An objective of the present invention is to provide an optical remote control system. 
         [0010]    Another objective of the present invention is to provide a method for controlling a light source of an optical remote control system. 
         [0011]    To achieve the foregoing objectives, in one aspect, the present invention provides an optical remote control system, comprising: a light source including a plurality of lighting units, the light source generating at least one light beam; an image sensor receiving an image including the light beam; and a processor determining a number or positions of the lighting units which are activated according to an area of the light beam in the image. 
         [0012]    In one embodiment of the foregoing optical remote control system, the area of the image of the light beam is represented by a number of pixels of the image, and the processor reduces the number of the lighting units which are activated when the number of pixels is larger than a first threshold; the processor increases the number of the lighting units which are activated when the number of pixels is smaller than a second threshold. 
         [0013]    In one embodiment of the foregoing optical remote control system, the light source changes the number and/or the positions of the lighting units which are activated according to a predetermined rule. 
         [0014]    In the foregoing optical remote control system, the light beam emitted from the lighting units can occupy a single area or multiple separated areas in the image received by the image sensor. 
         [0015]    In the foregoing optical remote control system, when the lighting units are not all activated at the same time, the light source preferably changes the positions of the lighting units which are activated in a predetermined order. 
         [0016]    In yet another aspect, the present invention provides a method for controlling an optical remote control system, the optical remote control system comprising a light source including a plurality of lighting units and an image sensor, the method comprising: generating at least one light beam from the light source; receiving an image including the light beam; and determining a number or positions of the lighting units which are activated according to an area of the light beam in the image. 
         [0017]    The objectives, technical details, features, and effects of the present invention will be better understood with regard to the detailed description of the embodiments below, with reference to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1A  shows a schematic diagram illustrating the use of a joystick in a prior art interactive video game system. 
           [0019]      FIGS. 1B-1C  show schematic diagrams illustrating the light spot in the image captured by the image sensor. 
           [0020]      FIG. 2A  shows a schematic diagram illustrating an optical remote control system of the present invention. 
           [0021]      FIG. 2B  shows a light spot in an image captured by the image sensor in  FIG. 2A . 
           [0022]      FIG. 3A  is a schematic diagram illustrating the lighting units of the light source which are activated. 
           [0023]      FIG. 3B  shows a light spot in an image captured by the image sensor in  FIG. 3A . 
           [0024]      FIG. 4A  is a schematic diagram illustrating the lighting units of the light source which are activated. 
           [0025]      FIG. 4B  shows two light spots in an image captured by the image sensor in  FIG. 4A . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    The optical remote control system and light source control method according to the present invention are applicable to computers, video players or interactive game systems, such as for moving a pointer on a display of a computer monitor, remote-control of a video player, remote-control of a smart TV, etc. Because an interactive game system is currently popular, it is taken as an example in the following description. 
         [0027]      FIG. 2A  shows a schematic diagram illustrating an optical remote control system of the present invention. As shown in this figure, the wireless remote control image display system  20  basically comprises a controller  21 , a game host  22 , a light source  23 , and an image display  24 . The game host  22  executes a video game program which is shown by the image display  24 . The image display  24  may be a screen, a projector, a head-mounted display, or other types of display apparatuses. A user operates the controller  21  to interact with the game host  22  such that the game host  22  executes various actions or instructions such as moving a pointer or a cursor  241  on the image display  24  to the menu at the right side. The light source  23  includes multiple lighting units  231 , each of which can be individually controlled to be turned on or turned off. The light source  23  may be, but not limited to, an infrared light source. 
         [0028]    When the controller  21  is operated by the user, the lighting units  231  of the light source  23  generate one or multiple infrared (IR) rays which are imaged in the image sensor  211  of the controller  21 . In this embodiment, the processor  213  is disposed in the controller  21 , but it can be disposed in the game host  22  in another embodiment. The game host  22  includes a transceiver  221 , which communicates with the transceiver  212  of the controller  21  through the radio frequency signals RF 1  and RF 2  (or IR signals) for bidirectional data transmission. In addition, the transceiver  212  of the controller  21  also can communicates with the transceiver  232  of the light source  23  through the radio frequency signals RF 3  and RF 4  (or IR signals) for bidirectional data transmission. In other embodiments, the aforementioned data transmission can be conducted in a wired way. 
         [0029]    In the prior art, all lighting units of the light source are turned on concurrently. However, when the distance between the light source and the image sensor is smaller than a minimum operating distance, the light spot is too large and cannot be recognizable. In the current embodiment, the processor  213  instructs the light source  23  to adaptively adjust the number of the lighting units  231  which are activated according to the information of the light spot in the captured image. That is, when the light spot is larger than the required size and covers too many pixels, the processor  213  sends a signal to the light source  23  to reduce the number of the turned-on lighting units  231 , until the processor  213  determines that the light spot covers a proper pixel area. Referring to  FIG. 2A , three of the six lighting units  231  are turned on, and the other three are turned off, so that the image sensor  211  can capture an image in a shorter distance to the light source  23 . The adjustment instruction can be communicated in various ways, depending on where the processor  213  is located. For example, the processor  213  can send the instruction to the light source  23  directly, through the radio frequency signal RF 3 , or indirectly, to the game host  22  (such as when the processor  213  is located in the game host  22 ) and the game host  22  sends the instruction to the light source  23 . 
         [0030]      FIG. 2B  shows a lighting spot in an image captured by the image sensor in  FIG. 2A . Because three of the lighting units  231  in  FIG. 2A  are turned on, the light spot  251  in the image  25  covers two pixels (in the current embodiment, it is assumed that the preferable size is 2-4 pixels). In response to the distance change between the image sensor  211  and the light source  23 , the number of the lighting units  231  which are activated can be adjusted in order to obtained a better light spot  251  (preferable pixel number). When the user increases the distance between the controller  21  and the light source  23 , the light spot becomes smaller or vague, for example occupying only one pixel. In response, the number of the turned-on lighting units  231  can be increased. For example, six of the lighting units  231  are all turned on to keep the size of the light spot to be 2-4 pixels. Thus, the number of the lighting units  231  which are activated is dynamically adjusted; as a result, the operating distance of the optical remote control system can be extended and the electrical power can be effectively saved. That is, although the light spot covering 2-4 pixels can be recognized, it can be controlled so that the light spot only covers an area of the minimum required pixel number (two pixels in this embodiment); in this way the number of the lighting units  231  which are activated is reduced and the electrical power is saved. 
         [0031]    Furthermore, when the lighting units are not activated all at the same time, the light source  23  can change the positions of the lighting units  231  which are activated in a predetermined order after a period of time. This can prolong the lifetime of the lighting units. 
         [0032]    That the lighting units  231  of the light source  23  can be individually controlled provides benefits that the image sensor  211  can obtain an optimal image and the electrical power can be effectively saved. In addition to such benefits, the lighting units  231  of the light source  23  can be individually controlled for identification or for other functions. The lighting units  231  of the light source  23  can be selectively turned on according to a predetermined rule. For example, the number and/or the positions of the lighting units  231  which are activated are sequentially changed after a certain interval (e.g., 1 second). Such alternating lighting can be used as a communication protocol between the light source  23  and the controller  21 , for functions such as expressing a request to initializing communication, a position confirmation, or any other specific request. An application of such communication may when the controller  21  receives sequential images according to a predetermined rule, it can confirm the identity of the light source and determines whether to start communication with the light source, or to filter undesired interference light if the images do not express a defined protocol. For example, when the light source  23  is interfered by other surrounding light sources, the controller  21  cannot identify which light spot in the image  25  corresponds to the light source  23  that the image sensor  211  intends to receive light from. In this case, the controller  21  can send an identification request to the light source  23 , such as to regularly and sequentially activate the lighting units  231 , for position confirmation. 
         [0033]    In addition to the foregoing benefits, that the lighting units  231  of the light source  23  can be individually controlled can be used to provide other control functions.  FIG. 3A  is a schematic diagram illustrating the lighting units of the light source which are activated. The two left lighting units  231  are activated, and the four right ones are inactivated. Referring to  FIG. 3B , because the lighting units  231  are activated in the manner as shown in  FIG. 3A , the light spot  252  covers two pixels in one area in the image  25 . The light spot  252  can be used for detecting a two dimensional movement of the controller  21 , such as for controlling the movement of the cursor  241  on the image display  24 . That is, the light source  23  generates a single light spot under this condition. 
         [0034]      FIG. 4A  is a schematic diagram illustrating the lighting units of the light source which are activated. The two left and two right lighting units  231  are activated, and the two middle ones are turned off. Referring to  FIG. 4B , because the lighting units  231  are activated in the manner as shown in  FIG. 4A , the image  25  includes two light spots  253 , each covering two pixels, with two dark pixels in between. That is, the light source  23  forms multiple light spots. The two light spots  253  can be used for detecting a three dimensional movement of the controller  21 . When the controller  21  moves closer and farther relative to the light source (out-of-plane movement), the distance between the two light spots  253  is changed, and the change can be used to calculate the displacement in the out-of-plane direction. The three dimensional movement of the controller  21  can be used to rotate an object on the image display  24  or to control the object to make a three dimensional movement. 
         [0035]    The present invention has been described in considerable detail with reference to certain preferred embodiments thereof. It should be understood that the description is for illustrative purpose, not for limiting the scope of the present invention. Those skilled in this art can readily conceive variations and modifications within the spirit of the present invention. For example, the positions of the light source  23  and the image sensor  211  can be exchanged, and the image sensor  211  does not necessary have to be disposed in the controller  21 . For another example, the controller  21 , the game host  12 , and the light source  23  can commute with each other in a wired or wireless manner not limited to the manner as shown in the drawings. Furthermore, multiple thresholds can be set to confine the pixel number of the light spot. For example, a first threshold is set which defines the maximum pixel number, and if this threshold is reached, the system reduces the number of the lighting units which are activated; a second threshold is set which defines the minimum pixel number of the recognizable pixel area, and if this threshold is reached, the system increases the number of the lighting units which are activated. Thus, the present invention should cover all such and other modifications and variations, which should be interpreted to fall within the scope of the following claims and their equivalents.