Patent Publication Number: US-2006007173-A1

Title: Combined digitizer tablet and external power supply device for an electronic apparatus

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a peripheral device for an electronic apparatus, more particularly to a combined digitizer tablet and external power supply device for application to an electronic apparatus.  
      2. Description of the Related Art  
      Digitizer tablets are used by computer users desiring an ability to input information by hand. Digitizer tablets also have other applications, such as in electronic dictionaries. Such digitizer tablets are becoming increasingly common as handwriting recognition technology improves, and as they are used for an ever-increasing range of applications.  
      Another device experiencing increased growth in usage is the external power supply. Portable electronic apparatuses, such as laptop computers, are typically equipped with internal rechargeable batteries. However, a common problem encountered by users of portable electronic apparatuses is the limited run time provided by the batteries mounted in the device. If there is no power outlet to plug into, the user has no choice but to discontinue further use of the apparatus. One way in which users of portable electronic apparatuses overcome this problem is to use an external power supply device that typically plugs into the DC adaptor socket. This enables continued use of the portable electronic apparatus.  
      With respect to the digitizer tablet, a drawback of this device is that when the electronic apparatus is not connected to an AC power outlet, the digitizer tablet draws power from the internal rechargeable batteries of the apparatus to which it is connected, thereby exacerbating the problem of limited run time. Furthermore, when the user of the electronic apparatus desires to employ both the digitizer tablet and the external power supply, connection of these units separately makes the area around the electronic apparatus disorganized, and reduces the portability of the electronic apparatus.  
     SUMMARY OF THE INVENTION  
      Therefore, the object of the present invention is to provide a combined digitizer tablet and external power supply device for an electronic apparatus that minimizes an adverse affect on the portability of the electronic apparatus through the merging of these two devices, and that uses its own power to run the digitizer tablet.  
      According to the present invention, a combined digitizer tablet and external power supply device for an electronic apparatus includes a housing having a working surface. A sensing tablet unit is disposed on the working surface of the housing, and is operable so as to generate electrical signals in response to writing activity thereon. A battery unit is disposed in the housing. A control circuit is coupled electrically to the sensing tablet unit and the battery unit, and receives the electrical signals from the sensing tablet unit to generate coordinate position data corresponding to the electrical signals.  
      A data communications unit is mounted in the housing. The data communications unit is coupled electrically to the control circuit, and is adapted to establish a communications link with the electronic apparatus so as to enable transmission of the coordinate position data from the control circuit to the electronic apparatus.  
      A power output unit is mounted in the housing. The power output unit is coupled electrically to the control circuit, and is adapted to be coupled electrically to the electronic apparatus. The control circuit is operable so as to control the supply of battery power from the battery unit to the electronic apparatus via the power output unit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:  
       FIG. 1  is a perspective view of a combined digitizer tablet and external power supply device for an electronic apparatus according to a preferred embodiment of the present invention, in which the combined digitizer tablet and external power supply is shown connected to an electronic apparatus;  
       FIG. 2  is a perspective view of the preferred embodiment;  
       FIG. 3  is a schematic view to illustrate a control circuit and a battery unit of the preferred embodiment;  
       FIG. 4  is a schematic circuit block diagram of the preferred embodiment; and  
       FIG. 5  is a schematic circuit block diagram of a control circuit of the preferred embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to  FIGS. 1 and 2 , a combined digitizer tablet and external power supply device  1  according to a preferred embodiment of the present invention is electrically connected to an electronic apparatus  2 , such as a laptop computer. The electronic apparatus  2  includes a monitor  21 .  
      The combined digitizer tablet and external power supply device  1  according to the preferred embodiment of the present invention includes a housing  11 , a sensing tablet unit  12 , a battery unit  13 , a control circuit  14 , a display unit  15 , a data communications unit  16 , a power input unit  17 , and a power output unit  18 . The housing  11  has a working surface  110 .  
      The sensing tablet unit  12  is disposed on the working surface  110  of the housing  11 , and generates electrical signals (i.e., sensing signals) in response to writing activity thereon in a conventional manner. The sensing signals are typically generated by movement of a stylus  31  on the sensing tablet unit  12  by a user  3 . After generation of the sensing signals, the sensing tablet unit  12  transmits the sensing signals to the control circuit  14 . The sensing tablet unit  12  may be a resistive-type tablet, a capacitive-type tablet, or an inductive-type tablet.  
      Referring to  FIGS. 2 and 3 , the battery unit  13  is mounted in the housing  11  and includes at least one battery cell  131 . In the preferred embodiment, the battery unit  13  includes a plurality of the battery cells  131 , and each of the battery cells  131  is rechargeable. The battery cells  131  may be lithium-ion (Li-ion) battery cells, nickel-metal hydride (Ni-MH) battery cells, lithium-polymer (Li-polymer) battery cells, nickel cadmium (Ni—Cd) battery cells, fuel cells, nickel-hydrogen (Ni—H) battery cells, etc.  
      Referring to  FIGS. 2, 4 , and  5 , the control circuit  14  is mounted in the housing  11 . The control circuit  14  receives the sensing signals generated by the sensing tablet unit  12 , converts the sensing signals into corresponding coordinate position data, and then transmits the coordinate position data to the electronic apparatus  2 . The control circuit  14  is also responsible for display operation of the display unit  15  and power management of the battery unit  13 . All of these operations of the control circuit  14  will be described in greater detail hereinafter.  
      The control circuit  14  includes a battery managing unit  141  coupled electrically to the battery unit  13  to manage the same, a signal processing unit  143  coupled electrically to the sensing tablet unit  12  to receive the sensing signals from the same, and a central control unit  142  coupled electrically to the signal processing unit  143  and the battery managing unit  141  to coordinate operations of the same. The battery managing unit  141  includes a charge/discharge unit  144 , a protection unit  145 , and a detection unit  146 .  
      The charge/discharge unit  144  maintains voltage and current levels during charging and discharging of the battery unit  13  to within acceptable levels. The central control unit  142  controls the charging and discharging of the battery cells  131  of the battery unit  13  via the charge/discharge unit  144 , and respectively via the power input unit  17  and the power output unit  18 . The power input unit  17  is mounted on the housing  11 , and is coupled electrically to the control circuit  14 . The power input unit  17  is adapted to receive a charging signal for charging the battery cells  131 . Each of the battery cells  131  includes a pair of terminals  132 , and each terminal  132  is electrically coupled to the control circuit  14  such that the battery cells  131  are charged or discharged under the control of the control circuit  14 . As with the power input unit  17 , the power output unit  18  is mounted on the housing  11 , and is coupled electrically to the control circuit  14 . The power output unit  18  is operable to control the supply of battery power from the battery unit  13  to the electronic apparatus  2  (see  FIG. 1 ).  
      The protection unit  145  of the battery managing unit  141  is used to protect the battery unit  13  by performing a cutting off operation when a temperature of the battery unit  13  exceeds a predetermined level, or when overvoltage and/or overcurrent problems occur in the battery unit  13 .  
      The detection unit  146  detects battery status variables, such as voltage and capacity, and generates corresponding battery status signals. The detection unit  146  then transmits the battery status signals to the central control unit  142 . The battery status signals generated by the detection unit  146  are processed by the central control unit  142 , which then controls the display unit  15  to display battery status information thereon. The display unit  15  may be a liquid crystal display (LCD) or a light emitting diode (LED) display.  
      The signal processing unit  143  of the control circuit  14  receives the sensing signals transmitted by the sensing tablet unit  12 , and performs analog-to-digital conversion of the sensing signals. The resulting digital signals are then transmitted to the central control unit  142 , where the digital signals are converted into corresponding coordinate position data.  
      The data communications unit  16  is mounted in the housing  11 , and is coupled electrically to the control circuit  14 . The data communications unit  16  is adapted to establish a communications link with the electronic apparatus  2  so as to enable transmission of the coordinate position data from the central control unit  142  of the control circuit  14  to the electronic apparatus  2 . The data communications unit  16  may establish a wired or wireless communications link with the electronic apparatus  2 . The wired communications link may be a USB communications link or a 1394 communications link. The wireless communications link may be an infrared (IR) communications link or a radio frequency (RF) communications link.  
      In the combined digitizer tablet and external power supply device  1  of the present invention described above, an adverse affect on the portability of the electronic apparatus  2  is minimized by merging writing tablet and external battery pack capabilities into a single system. Further, the run time of the electronic apparatus  2  is increased by using the power of the battery unit  13  to operate the sensing tablet unit  12 , rather than the internal batteries of the electronic apparatus  2 .  
      While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.