Abstract:
A wireless optical pointing device. The wireless optical pointing device comprises a photo sensor detecting a series of continuous images on an operating surface, a processing unit coupled with the photo sensor, processing the detected images, and outputting an image displacement signal accordingly, and a RF (Radio Frequency) unit coupled with the processing unit and transmitting a RF signal according to the image displacement signal, wherein the photo sensor and the RF unit receive a common oscillation frequency source and operate accordingly.

Description:
BACKGROUND 
   The present invention relates to a wireless optical pointing device. 
   A mouse is a commonly used input device. A wheel mouse processes displacement, button, and interface signals and communicates with a computer via an interface using the mechanical structure of its wheel and a micro-controller chip. An optical mouse replaces the mechanical structure of the wheel mouse with a complementary metal oxide semiconductor (CMOS) photo sensor chip capable of optical navigation. The CMOS photo sensor detects a series of continuous images on an operating surface. The displacement of the optical mouse can be determined by processing the images. Moreover, the mouse can communicate with the computer wirelessly via signal transmission. 
     FIG. 1   a  is a diagram of a conventional wireless optical mouse  10 .  FIG. 1   b  is a diagram showing a photo sensor  13 , an MCU (Micro-Controller Unit)  14 , a RF (Radio Frequency) transmitter  15 , and two crystal oscillators  16  and  17  inside the wireless optical mouse  10  in  FIG. 1   a . As shown in  FIG. 1   b , typically, a wireless optical mouse  10  has a photo sensor  13 , an MCU (Micro-Controller Unit)  14 , and a RF transmitter  15 . The photo sensor  13  is provided with an oscillation frequency by a crystal oscillator  16 . The RF transmitter  15  is provided with an oscillation frequency by another crystal oscillator  17 . When the wireless optical mouse  10  is operated, the photo sensor  13  outputs a displacement of the wireless optical mouse  10  to the MCU  14 . The MCU  14  then converts the received displacement of the wireless optical mouse  10  and button state information as a modulation signal and outputs the modulation signal to the RF transmitter  15 . Thus, the RF transmitter  15  transmits the displacement and the button state information to a computer (not shown in drawings) via a RF carrier wave (not shown in drawings). The RF carrier wave is provided by the crystal oscillator  17 . 
   Due to frequency band limitations, the RF transmitter  15  of the wireless optical mouse  10  typically operates within a frequency in the citizen band (CB) such as 27 megahertz (MHz). Thus, the crystal oscillator  17  provides a RF carrier wave of 27 MHz to the RF transmitter  15 . Additionally, the photo sensor  13  typically operates at 18.43 MHz, so the crystal oscillator  16  provides an oscillation signal of 18.43 MHz to the photo sensor  13 . Thus, the wireless optical mouse  10  requires two separate crystal oscillators  16  and  17 , thus increasing production cost and power consumption. 
   SUMMARY 
   Accordingly, an embodiment of a wireless optical pointing device comprises a photo sensor detecting a series of continuous images on an operating surface, a processing unit coupled with the photo sensor, processing the detected images, and outputting an image displacement signal accordingly, and a RF (Radio Frequency) unit coupled with the processing unit and transmitting a RF signal according to the image displacement signal, wherein the photo sensor and the RF unit receive a common oscillation frequency source and operate accordingly, and the photo sensor and the processing unit are integrated on the same chip. 
   A detailed description is given in the following embodiments with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
       FIG. 1   a  is a diagram of a conventional wireless optical mouse. 
       FIG. 1   b  is a diagram showing a photo sensor, an MCU (Micro-Controller Unit), a RF transmitter, and two crystal oscillators inside the wireless optical mouse in  FIG. 1   a.    
       FIG. 2   a  is a diagram of the wireless optical mouse in a first embodiment of the invention. 
       FIG. 2   b  is a diagram showing a photo sensor, an MCU, a RF transmitter, and a crystal oscillator inside the wireless optical mouse in  FIG. 2   a.    
       FIG. 3   a  is a diagram of the wireless optical mouse in a second embodiment of the invention. 
       FIG. 3   b  is a diagram showing an integrated chip inside the wireless optical mouse in  FIG. 3   a.    
   

   DETAILED DESCRIPTION 
   A principle aim of the invention is to reduce the number of crystal oscillators in a wireless optical mouse by employing a photo sensor and a RF transmitter using a common oscillator inside the photo sensor. The photo sensor must be designed to be capable of operating at a system frequency in the citizen band (CB) such as 27 megahertz (MHz). 
   First Embodiment 
     FIG. 2   a  is a diagram of the wireless optical mouse  20  in the first embodiment of the invention.  FIG. 2   b  is a diagram showing a photo sensor  23 , an MCU  24 , a RF transmitter  25 , and a crystal oscillator  26  inside the wireless optical mouse  20  in  FIG. 2   a . As shown in  FIG. 2   b , the wireless optical mouse  20  has a photo sensor  23 , an MCU  24 , and a RF transmitter  25 . The photo sensor  23  and the RF transmitter  25  receive oscillation frequencies provided by a common crystal oscillator  26  and operate accordingly. When the wireless optical mouse  20  is operated on an operating surface, the photo sensor  23  detects a series of continuous images on the operating surface. The displacement of the wireless optical mouse  20  can be determined by processing the images and output to the MCU  24  coupled with the photo sensor  23 . The MCU  24  then converts the received displacement and button information as a modulation signal and outputs the modulation signal to the RF transmitter  25  coupled with the MCU  24 . Thus, the RF transmitter  25  transmits the displacement and the button information to a computer (not shown in drawings) via a RF carrier wave (not shown in drawings). 
   Because the photo sensor  23  and the RF transmitter  25  are electrically coupled to a common crystal oscillator  26 , the photo sensor  23  and the RF transmitter  25  receive oscillation frequencies provided by the common crystal oscillator  26  and operate accordingly. The common crystal oscillator  26  provides the photo sensor  23  and the RF transmitter  25  with the same oscillation frequency, or alternatively with different oscillation frequencies respectively. Oscillation frequencies provided by the common crystal oscillator  26  are located in HF (High Frequency) or VHF (Very High Frequency) bands, for example, in the citizen band (CB) such as 27 megahertz (MHz). 
   In this embodiment, the photo sensor  23  and the RF transmitter  25  are electrically coupled to the common crystal oscillator  26 , so the number of crystal oscillators in the wireless optical mouse  20  is reduced, thereby reducing the volume and the production cost of the wireless optical mouse  20 . 
   Second Embodiment 
     FIG. 3   a  is a diagram of the wireless optical mouse  30  in the second embodiment of the invention.  FIG. 3   b  is a diagram showing an integrated chip  31  inside the wireless optical mouse  30  in  FIG. 3   a . As shown in  FIGS. 3   a  and  3   b , the wireless optical mouse  30  has an integrated chip  31  comprising a photo sensor circuit  33  and an MCU circuit  34 . The wireless optical mouse  30  further comprises a RF transmitter circuit  35  coupled with the MCU circuit  34 . The photo sensor circuit  33  and the RF transmitter circuit  35  receive oscillation frequencies provided by a common crystal oscillation circuit  36  and operate accordingly. The common crystal oscillation circuit  36  comprises a crystal  37  and an oscillation starting circuit  38 . The oscillation starting circuit  38  is integrated in the integrated chip  31 . When the wireless optical mouse  30  is operated on an operating surface, the photo sensor circuit  33  detects a series of continuous images on the operating surface. The displacement of the wireless optical mouse  30  can be determined by processing the images and output to the MCU circuit  34  coupled with the photo sensor circuit  33 . The MCU circuit  34  then converts the received displacement and button state information as a modulation signal and outputs the modulation signal to the RF transmitter circuit  35  coupled with the MCU circuit  34 . Thus, the RF transmitter circuit  35  transmits the displacement and the button state information to a computer (not shown in drawings) via a RF carrier wave (not shown in drawings). 
   Because the photo sensor circuit  33  and the RF transmitter circuit  35  are electrically coupled to a common crystal oscillation circuit  36 , the photo sensor circuit  33  and the RF transmitter circuit  35  receive oscillation frequencies provided by the common crystal oscillation circuit  36  and operate accordingly. The common crystal oscillation circuit  36  provides the photo sensor circuit  33  and the RF transmitter circuit  35  with the same oscillation frequency, or alternatively with different oscillation frequencies respectively. Oscillation frequencies provided by the common crystal oscillation circuit  36  are located in HF (High Frequency) or VHF (Very High Frequency) bands, for example, in the citizen band (CB) such as 27 megahertz (MHz). 
   In this embodiment, the photo sensor circuit  33  and the MCU circuit  34  are integrated in the integrated chip  31 , thereby reducing production cost, power consumption, chip pins, and external components, and improving the integration level of components in the wireless optical mouse  30 . 
   Alternatively, in this embodiment, the photo sensor circuit  33 , the MCU circuit  34 , and the RF transmitter circuit  35  can all be integrated in the integrated chip  31 . 
   Due to frequency band limitations, the RF transmitter  25 , or the RF transmitter circuit  35 , of the wireless optical mouse in embodiments of the present invention must operate within a frequency in the citizen band (CB) such as 27 MHz. Thus, the photo sensor  23 , or the photo sensor circuit  33 , must operate at 27 MHz accordingly. Conventionally, the photo sensor is tested at 18.43 MHz of design specification, other than 27 MHz. Thus, it must be verified that the photo sensor can operate normally in the citizen band (CB) when implementing embodiments of the present invention. When oscillation signals are modulated in the citizen band (CB), the RF transmitter  25 , or the RF transmitter circuit  35 , modulates the RF carrier wave of 27 MHz. Thus, it must be verified that the photo sensor can operate normally regardless of influence of the modulation process. Through testing and experimentation, those skilled in the art can achieve this requirement in designing circuits or chips. 
   In embodiments of the present invention, the photo sensor (or the photo sensor circuit) and the RF transmitter (or the RF transmitter circuit) are electrically coupled to a common crystal oscillator, thus reducing the number of required crystal oscillators, the volume, and the production cost of the wireless optical mouse. 
   Additionally, the photo sensor circuit and the MCU circuit are integrated in the same chip, thereby reducing production cost, power consumption and improving the integration level of components in the wireless optical mouse. 
   Alternatively, in embodiments of the present invention, the photo sensor circuit, the MCU circuit, and the RF transmitter circuit can be integrated in the same chip. 
   While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.