Patent Publication Number: US-2005134555-A1

Title: Pointing device for detecting hand-movement

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a pointing device for communicating with a computer system or the like, and in particular to a pointing device for controlling cursor movement on a display according to the outputs of two inertia or acceleration sensors, hereinafter “accelerometers,” for sensing changes in direction and speed of the pointing device.  
      2. Description of the Prior Art  
      A conventional pointing device simply projects a laser light over a screen to highlight content relevant to a speech. However, it is not able to change the content, which must be programmed using a computer.  
      On the other hand, a computer system is usually operated while a user sits at a table so as to utilize a pointing device moving on the table. Thus, the user cannot move around the audience to provide a vivid presentation.  
      A small pointing device has been developed to overcome the inconvenience mentioned above by using a gyroscope, shown in U.S. Pat. No. 5,898,421, U.S. Pat. No. 5,828,350, and U.S. Pat. No. 5,594,169. However, the pointing device is costly to produce because of the need for a very precise gyroscope to detect hand-movement of a user.  
      In addition, WO0211058 discloses a simple improvement to conquer the defects listed above, in which a trackball device wirelessly transmits to a computer system so as to move a cursor on a display. In general, a trackball device is more difficult to operate by a single finger (thumb or index) over a working surface, such a desktop, than a computer mouse, which is the reason why the mouse is much more popular than the trackball in the market. To train a user to precisely operate a trackball in the air (suspending the user&#39;s arm away from the working surface) is a very tough task.  
      A Taiwan patent publication, TW526978, discloses a pointing device that uses an accelerometer to detect the hand-movement in the air, in which the accelerometer calculates or detects its own change in speed. However, the accelerometer fails to truly respond the complicated hand-movement in the air due to the impractical design. According to an experiment conducted by the inventor, the pointing device disclosed in the patent is almost inoperative.  
     SUMMARY OF THE INVENTION  
      It is an object of the present invention to provide a stable and precisely controlled pointing device, which can truly respond to hand-movements so as to move a cursor on a display of a computer system.  
      It is another object of the present invention to provide a pointing device with a plurality of function keys for sending a command or execution to the computer according to the position of the cursor on the display.  
      It is yet another object of the present invention to provide a pointing device with a laser pointer for facilitating conduct of a presentation or explication on a projected screen.  
      It is yet another object of the present invention to provide a remote control to operate a digital TV or the like.  
      To accomplish the virtues described above, the pointing device comprises a micro control unit (MCU), and at least two accelerometers respectively located at a first position and a second position; and a wireless transmitting module that can wirelessly transmit a cursor-moving signal sent from the MCU. When a user operates the pointing device, the MCU calculates the difference in accelerations sensed by the two accelerometers, and sends the cursor-moving signal to a computer system. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a circuit diagram of the first embodiment according to the present invention.  
       FIG. 2  is a circuit diagram of the second embodiment according to the present invention.  
       FIG. 3  is a top view according to  FIG. 2 .  
       FIG. 4  is a diagram showing the movement when a user operates the preset invention.  
       FIG. 5  is a diagram showing the operation of the present invention connecting to a projector or computer. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The following detailed description is of the best presently contemplated modes of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating general principles of embodiments of the invention. The scope of the invention is best defined by the appended claims.  
      The present invention is a pointing device, which can be used to work with a computer system, a projector, or a digital TV system. The pointing device can be wired, or wirelessly communicate with the devices mentioned above. Hereinafter, the pointing device is, by way of example, illustrated as a wireless pointing device.  
      Referring to  FIGS. 1, 3  and  5 , the first embodiment of the present invention comprises a micro control unit (MCU)  10 ; at least two accelerometers  11 ,  12  respectively located at a first position and a second position; and a wireless transmitting module  13  arranged to wirelessly transmit a cursor-moving signal sent from the MCU  10 . When a user operates the pointing device  20 , for example by waving it in the air, the MCU  10  calculates the difference in accelerations sensed by the two accelerometers  11 ,  12 , and sends the cursor-moving signal to a computer system or the like. Therefore a cursor  32  on the display (not shown) of the computer system  30  will move correspondingly.  
      In order to stabilize the output voltages of accelerometers  11  and  12 , voltage follower  18  is respectively located between sensors  11 ,  12  and the MCU  10 . A plurality of function keys  14 ,  15 ,  16  and  17 , representing different key codes, are coupled to the MCU  10 . Therefore, when a user operates the pointing device  20  to move the cursor  32  on the display (not shown), and clicks any of the keys, the pointing device will not only move the cursor on the display, but also correspondingly send a command or execution to the computer  30  (such as copy, delete, print, hyperlink . . . ) according to the position of the cursor  32  on the display (not shown). The function key  17  can be a roller like device for scrolling the content in an application window or for executing a Page Up/Page Down function.  
      Referring to  FIGS. 2 and 3 , is the second embodiment of the present invention. A laser pointer  19  is further incorporated within the pointing device  20 . The laser pointer  19  connects to power supply Vcc via a switch  191 , and MCU  10 . When the switch  191  is activated, the laser pointer  19  is connected to the Vcc and emits a light beam. When a user operates the pointing device  20 , a cursor  32  projected by a projector  30  on the screen  31  will move correspondingly. The user can move the beam over a screen  31  for highlighting a projected content. However the MCU  10  may also enter a sleep mode to stop working and save the power of the pointing device  20 .  
      Referring to  FIGS. 3 and 4 , the shape or outline of the pointing device  20  can be ergonomically designed to match the hand, with the sensor  11  positioned at a front of the device and the sensor  12  positioned at a rear of the device. When the user operates the pointing device  20  in the air, the MCU  10  will receive two acceleration signals simultaneously. Then, the MCU  10  will calculate the difference between the two acceleration signals, and correspondingly generate a cursor-moving signal for transmission to the computer  30 , so as to move the cursor  32  on the screen  31  and on the display of the computer. With key  191  is pressed, the laser pointer  19  will emit a light beam over the screen  31  for further indicating.  
      Please notice that the number of accelerometers is not limited to two, so long as the accelerations speeds detected by the sensors differ by an amount that enables calculation and comparison of the MCU  10  to generate a cursor-moving signal.  
      While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention.