Abstract:
The present invention discloses a cordless electromagnetic induction system, which comprises a cordless pen and a tablet, connecting to a host. In this regards, the cordless pen comprises a battery for supplying power to the pen, a RF (radio frequency)oscillator circuit for generating radio frequency signal, representing the location and status of the pen at a central frequency, and a battery voltage detection apparatus for detecting the output voltage of the battery. The battery voltage detection apparatus commands the RF oscillator circuit for generating a signal, which central frequency is at a warning frequency, while the output voltage of the battery is lower than a critical value. The tablet comprises a tablet RF receiver for receiving RF signal from the RF oscillator circuit. The tablet informed the host for raising a low battery power warning to user while the tablet RF receiver received a signal, which central frequency is at the warning frequency.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to cordless electromagnetic induction system, and more particularly to cordless electromagnetic induction system and method for reminding battery capacity.  
         [0003]     2. Description of the Prior Art  
         [0004]     Hand-writing recognition apparatus performs as well as computer mouse. Since it is more suitable for drawing and graphics operations than mouse, the development and improvement of hand-writing recognition apparatus is harvest in recent years. The earliest concept of hand-writing recognition apparatus is to replace mouse by pen. For the convenience, a cordless pen and a corresponding tablet is taken place of mouse. Therefore the left button of mouse is usually replaced by the tip of the cordless pen. Although this product is on the shelf for a few years, the normal applications of this kind of product are restricted in graphics and writing input.  
         [0005]     Current hand-writing input product is usually a cordless electromagnetic induction system, which comprises a cordless pen with a battery and a tablet. Moreover, the cordless pen comprises an oscillation circuit composed by capacitor. Whenever the tip is touched or pressed, the capacitance would be changed accordingly. Hence the variation of oscillation frequency of the oscillation circuit is also changed in proportional to the difference of the capacitance. Therefore the pressure on the tip could be induced from the variation of oscillation frequency. Furthermore, there may be at least one button on the side of the cordless pen. By the way, the capacitance of the oscillation circuit is also changed according to the status of the button. Therefore the press of the button could be induced from the variation of oscillation frequency. In the other hands, the tablet comprises several components such as detectors, amplifiers, and ADC (analog to digital converter). The central working area of the tablet is the sensor circuit, which comprises arrayed receiving antenna in double sides. The main purpose of the receiving antenna is to receive RF (radio frequency) signal of the corresponding cordless pen, merely. Whenever the pen radiated some RF signal, it would be picked up by the receiving antenna and be translated into some useful information by the tablet.  
         [0006]     No matter the battery of the cordless pen is rechargeable or not, the battery power is limited. In the conventional system, users cannot know how much battery power remained. Usually after checking the whole system, user finally finds out that the conventional system is out of battery, not mal-functioned. It not only wastes the check time, but also enhances the un-reliability belief on this system. Moreover, user may not replace or re-charge battery immediately to use the system. Summarized, there exists a need for a cordless electromagnetic system and method for reminding battery capacity to solve these problems.  
       SUMMARY OF THE INVENTION  
       [0007]     Therefore, in accordance with the previous summary, objects, features and advantages of the present disclosure will become apparent to one skilled in the art from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.  
         [0008]     One object of this invention is to disclose a cordless electromagnetic induction system, which comprises a cordless pen and a tablet, connecting to a host. In this regards, the cordless pen comprises a battery for supplying power to the pen, a RF (radio frequency)oscillator circuit for generating radio frequency signal, representing the location and status of the pen at a central frequency, and a battery voltage detection apparatus for detecting the output voltage of the battery. The battery voltage detection apparatus commands the RF oscillator circuit for generating a signal, which central frequency is at a warning frequency, while the output voltage of the battery is lower than a critical value. The tablet comprises a tablet RF receiver for receiving RF signal from the RF oscillator circuit. The tablet informed the host for raising a low battery power warning to user while the tablet RF receiver received a signal, which central frequency is at the warning frequency.  
         [0009]     Another object of this invention is to disclose cordless electromagnetic induction system, which comprising a cordless pen, and a tablet, connecting to a host. In this regards, the cordless pen comprising a battery for supplying power to said cordless pen, a RF oscillation and a battery voltage detection apparatus. The RF oscillation circuit is configured to generate RF signal at a central frequency, representing the location and status of said cordless pen, said central frequency could be switched, by said RF oscillation circuit, to one of a plurality of warning frequencies or to a special warning frequency according to what received is one of a plurality of warning signals, corresponding to said plurality of warning frequencies, or a special warning signal, corresponding to said special warning frequency. The battery voltage detection apparatus is configured to detect an output voltage of said battery. A plurality of battery voltage values correspondent to said plurality of warning signals are defined between the maximum voltage of said battery and zero voltage, said special warning signal is sent to said RF oscillation circuit when said output voltage is lower than all of said plurality of battery voltage values for generating RF signal at said special warning frequency as central frequency. One of said plurality of warning signals is sent to said RF oscillation circuit when said output voltage is higher than one of said plurality of battery voltage values, correspondent to said sent warning signal, for generating RF signal at one of said plurality of special warning frequencies, correspondent to said sent warning signal, as central frequency. The tablet comprising a tablet RF receiver for receiving RF signal, representing the location and status of said cordless pen, said host was informed by said tablet for issuing a low voltage warning signal, representing said output voltage is higher than said battery voltage value, to user when received RF signal is at said warning frequency, correspondent to said battery voltage value, as central frequency.  
         [0010]     Accordingly, the user could know the remained battery power capacity with the help of the system provided by the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the disclosure. In the drawings:  
         [0012]      FIG. 1  is a block diagram shows a cordless electromagnetic induction system for reminding battery capacity of an embodiment in accordance with the present invention;  
         [0013]      FIG. 2A  is a flow chart diagram of the cordless pen shown in the  FIG. 1 ;  
         [0014]      FIG. 2B  is a flow chart diagram of the tablet shown in the  FIG. 1 ;  
         [0015]      FIG. 3  is a block diagram shows a cordless electromagnetic induction system for reminding battery capacity of another embodiment in accordance with the present invention;  
         [0016]      FIG. 4  is a diagram depicts frequencies and signals applied on the system shown in the  FIG. 3 ;  
         [0017]      FIG. 5A  is a flow chart diagram of the cordless pen shown in the  FIG. 3 ; and  
         [0018]      FIG. 5B  is a flow chart diagram of the tablet shown in the  FIG. 3 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     The present disclosure can be described by the embodiments given below. It is understood, however, that the embodiments below are not necessarily limitations to the present disclosure, but are used to a typical implementation of the invention.  
         [0020]     Having summarized various aspects of the present invention, reference will now be made in detail to the description of the invention as illustrated in the drawings. While the invention will be described in connection with these drawings, there is no intent to limit it to the embodiment or embodiments disclosed therein. On the contrary the intent is to cover all alternatives, modifications and equivalents included within the spirit and scope of the invention as defined by the appended claims.  
         [0021]     It is noted that the drawings presents herein have been provided to illustrate certain features and aspects of embodiments of the invention. It will be appreciated from the description provided herein that a variety of alternative embodiments and implementations may be realized, consistent with the scope and spirit of the present invention.  
         [0022]     It is also noted that the drawings presents herein are not consistent with the same scale. Some scales of some components are not proportional to the scales of other components in order to provide comprehensive descriptions and emphasizes to this present invention.  
         [0023]     Please refer to  FIG. 1 , which is a block diagram shows a cordless electromagnetic induction system  100  for reminding battery capacity of an embodiment in accordance with the present invention. The system  100  comprises a cordless pen  130  and a tablet  120 , connecting to a host  110 . In this regards, the cordless pen  130  further comprises a battery  131  for supplying power to the cordless pen  130 , a RF (Radio Frequency) oscillation circuit  132 , a battery voltage detection apparatus  133 , a battery warning light  134  connecting to the battery voltage detection apparatus  133 , at least one button  135 , and a tip  136 . The button  135  and the tip  136  are connected to the RF oscillation circuit  132 . When the button  135  and/or the tip  136  are pressed or touched, the frequency of radio emitted by the RF oscillation circuit  135  would be changed according to the level of pressure. Therefore a tablet RF receiver  121  of the tablet  120  would know the pressure level of the button  135  and/or the tip  136  according to the received radio frequency emitted by the RF oscillation circuit  132 . Generally, the host  110  usually comprises an OS (operating system)  111  and a driver  112  for communicating the system  100  and the OS  111 .  
         [0024]     As shown in the  FIG. 1 , the battery voltage could be detected by the battery voltage detection apparatus  133 , which is connected to the RF oscillation circuit  132 . In one example of this embodiment, the maximum output voltage of this battery is 1.5 volt and the radio emitted by the RF oscillation circuit  132  is maintained at a normal frequency, for example, 170 kHz. When the battery power consumed, once the output voltage detected by the battery voltage detection apparatus  133  is under a threshold, a low voltage signal would be sent to the RF oscillation circuit  132 . Accordingly, the radio emitted by the RF oscillation circuit  132  would be maintained at another warning frequency, for example, 120 kHz. If the output voltage of the battery  131  is remained above the threshold, a normal voltage signal would be sent to the RF oscillation circuit  132  from the battery voltage detection apparatus  133 . Therefore the radio emitted by the RF oscillation circuit  132  is still maintained at the normal frequency. Once the central frequency, received by the tablet RF receiver  121 , is changed to the warning frequency from the normal frequency, the driver  112  would be informed by the tablet  120 . Hence, a low voltage warning signal would be sent to user by the driver  112  through the help of the OS  111 . In this regards, the low voltage warning signal could be any audio and/or visual signal, popup window, flash, color change on the screen and/or other forms. The present invention does not restrict the form of the low voltage warning signal.  
         [0025]     In one example of the embodiment, the warning frequency is lower than the normal frequency for reducing the power consumption. In another example of the embodiment, the RF oscillation circuit  132  could further comprises a normal oscillation circuit  137  for emitting radio at the normal frequency and a warning oscillation circuit  138  for emitting radio at the warning frequency. In such case, the power consumption of the warning oscillation circuit  138  is lower than the power consumption of the normal oscillation circuit  137 . In another example of the embodiment, the battery warning light  134  would be turned on when the voltage detected by the battery voltage apparatus  133  is lower than the threshold.  
         [0026]     Please refer to the  FIG. 2A , which is a flow chart diagram of the cordless pen  130  shown in the  FIG. 1 . In a step  210 , the output voltage of the battery  131  is detected by the battery voltage detection apparatus  133 . Next, the detected voltage is compared with the threshold by the battery voltage detection apparatus  133  in a step  220 . If the output voltage is higher than the threshold, the normal voltage signal would be sent to the RF oscillation circuit  132  by the battery voltage detection apparatus  133  in a step  230 ; otherwise, the warning voltage signal would be sent to the RF oscillation circuit  132  by the battery voltage detection apparatus  133  and/or the battery warning light  134  would be turned on in a step  240 . Finally, the flow chart returns to the step  210  and repeats itself continuously.  
         [0027]     Please refer to the  FIG. 2B , which is a flow chart diagram of the tablet  120  shown in the  FIG. 1 . A central frequency of radio is received by the tablet RF receiver  121  in a step  250 . Next, the received central frequency is compared with the warning frequency in a step  260 . If the received central frequency is equal to the warning frequency, the driver  112  is informed by the tablet  120 . The low voltage warning signal would be issued via the OS  111 . Finally, the flow chart returns to the step  250  and repeats itself continuously.  
         [0028]     Please refer to  FIG. 3 , which is a block diagram shows a cordless electromagnetic induction system  300  for reminding battery capacity of another embodiment in accordance with the present invention. The system  300  comprises a cordless pen  330  and a tablet  320 , connecting to a host  310 . In this regards, the cordless pen  330  further comprises a battery  331  for supplying power to the cordless pen  330 , a RF (Radio Frequency) oscillation circuit  332 , a battery voltage detection apparatus  333 , a battery warning light  334  connecting to the battery voltage detection apparatus  333 , at least one button  335 , and a tip  336 . The button  335  and the tip  336  are connected to the RF oscillation circuit  332 . When the button  335  and/or the tip  336  are pressed or touched, the frequency of radio emitted by the RF oscillation circuit  335  would be changed according to the level of pressure. Therefore a tablet RF receiver  321  of the tablet  320  would know the pressure level of the button  335  and/or the tip  336  according to the received radio frequency emitted by the RF oscillation circuit  332 . Generally, the host  310  usually comprises an OS (operating system)  311  and a driver  312  for communicating the system  300  and the OS  311 .  
         [0029]     As shown in the  FIG. 3 , the battery voltage could be detected by the battery voltage detection apparatus  333 , which is connected to the RF oscillation circuit  332 . In one example of this embodiment, the maximum output voltage of this battery is 1.5 volt and the radio emitted by the RF oscillation circuit  332  is maintained at a normal frequency, for example, 370 kHz.  
         [0030]     Please refer to the  FIG. 4 , which is a diagram depicts frequencies and signals applied on the system shown in the  FIG. 3 . The radio emitted by the RF oscillation circuit  332  could be switched at a plurality of central frequencies; each frequency is corresponding to a plurality of battery voltage values and a plurality of warning signals received by the RF oscillation circuit  332 . It is said that the plurality of battery voltage values, which are all lower than the maximum output voltage, are also corresponding to the plurality of warning signals. For convenience, a decreasing list is formed by the plurality of battery voltage values; in other words, a later voltage value is less than a former voltage value in this decreasing list. In one example of this embodiment, the corresponding pluralities of warning frequencies and signals are also forming decreasing lists. However, the present invention does not restrict that the plurality of warning frequencies and corresponding plurality of battery voltage values are listed in a decreasing order.  
         [0031]     When the power of batter  331  consumed, an actual battery voltage detected by the battery voltage detection apparatus  333  is higher than an Nth battery voltage value and lower than a N−1th battery voltage value, a Nth warning signal is issued by the battery voltage detection apparatus  333  to the RF oscillation circuit  332 . Subsequently, the radio emitted by the RF oscillation circuit  332  is maintained at an Nth warning frequency as central frequency. However, when the actual battery voltage is still higher than the first battery voltage value, a first warning signal is issued by the battery voltage detection apparatus  333  to the RF oscillation circuit  332 . Subsequently, the radio emitted by the RF oscillation circuit  332  is maintained at a first warning frequency as central frequency. Moreover, when the actual battery voltage is lower than the last and the smallest battery voltage value, a special warning signal is issued by the battery voltage detection apparatus  333  to the RF oscillation circuit  332 . Subsequently, the radio emitted by the RF oscillation circuit  332  is maintained at a special warning frequency as central frequency.  
         [0032]     In one example of the embodiment, the battery warning light  334  has a plurality of warning light signals corresponding to the pluralities of battery voltage values, warning signals, and warning frequencies. When an actual battery voltage detected by the battery voltage detection apparatus  333  is higher than an Nth battery voltage value and lower than a N−1th battery voltage value, the Nth warning light signal are displayed by the battery warning light  334 , ordered by the battery voltage detection apparatus  333 . In this example, the plurality of warning light signals may be presented by flash frequencies, color changes, or any combinations of flash frequencies and color changes. The present invention does not restrict the representation formats of the plurality of warning light signals displayed the battery warning light  334 .  
         [0033]     After receiving by the tablet RF receiver  321 , the tablet  320  determined that which one of the plurality of warning frequencies or the special warning frequency is equals to the central frequency of the received radio, and the driver  312  would be informed the result consequently. Therefore, a low voltage warning signal would be showed to user by the driver  312  via the OS  311 . In this regards, the low voltage warning signal could be any audio and/or visual signal, popup window, flash, color change on the screen and/or other forms. The present invention does not restrict the form of the low voltage warning signal. Moreover, the low voltage warning signal could be displayed as the plurality of battery voltage values, for example, 1.5 volt, 1.4 volt, and etc.  
         [0034]     Please refer to the  FIG. 5A , which is a flow chart diagram of the cordless pen  330  shown in the  FIG. 3 . In a step  510 , the output voltage of the battery  331  is detected by the battery voltage detection apparatus  333 . Next, the battery voltage detection apparatus  333  determines that which one of the plurality of warning signals should be sent to the RF oscillation circuit  332  according to the detected voltage in a step  520 . The RF oscillation circuit  332  emits radio in the corresponding warning frequency according to received warning signal in a step  540 . Finally, the flow chart returns to the step  510  and repeats itself continuously.  
         [0035]     Please refer to the  FIG. 5B , which is a flow chart diagram of the tablet  520  shown in the  FIG. 3 . A central frequency of radio is received by the tablet RF receiver  321  in a step  550 . Next, the received central frequency is determined as which one of the plurality of warning frequencies by the tablet  320  in a step  560 . In a following step  560 , the low voltage warning signal would be presented to user with the help of the OS  311 , in consequence of the driver  312  is informed by the tablet  320  with the result of the step  560 . Finally, the flow chart returns to the step  550  and repeats itself continuously.  
         [0036]     The foregoing description is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. In this regard, the embodiment or embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the inventions as determined by the appended claims when interpreted in accordance with the breath to which they are fairly and legally entitled.  
         [0037]     It is understood that several modifications, changes, and substitutions are intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.