Patent Publication Number: US-2012040711-A1

Title: Mobile telephone enabling a user to answer a call without pressing a button

Description:
BACKGROUND 
     The present disclosure relates to mobile communication devices such as mobile telephones. 
     A typical mobile telephone composes of a body, speaker unit, and buttons on the body that can receive commands from users. To receive a call, a user needs to press the ‘answer’ button. In some mobile telephones, however, the button is too small for user to press easily. The problem is aggravated when the user has to find the button to receive the call in a limited time before the caller hangs up. It is not uncommon that a user mistakenly presses the ‘cancel’ button instead of the ‘answer’ button. Moreover, when a user is driving a vehicle, it is difficult for the user to press a button to answer the call without being distracted from driving safely. Additionally, when a user has dirty hands or is holding something in hands, the user cannot easily press the ‘answer’ button to answer the call. 
     Therefore, there is a need for a user to answer calls on mobile telephone without pressing a button on the mobile telephone. 
     SUMMARY OF THE INVENTION 
     The disclosed invention apparatus allows a user to answer mobile phones without the need to press a button on the phone, which allows a user pre-occupied by another task such as driving, holding articles in hand, or doing work with dirty hands to easily answer a call on the mobile telephone. In another aspect, the present application allows a user to perform a plurality of functions without the need to press a button or to turn a wheel. The plurality of functions can include answering calls, changing volume, silencing a phone, or turning on vibration mode, etc. 
     In another aspect, the present application discloses simple design for a sensing system. The disclosed capacitive sensor includes a single electrode that can be flexibly mounted in a mobile telephone. The disclosed capacitance sensor does not have the limitations in physical layout and restriction on hand positions that exist in a pair of electrodes, which simplifies the device and reduces cost. 
     In a general aspect, the present invention relates to a mobile communication device that includes a device body; one or more capacitive sensors each having a single electrode; an oscillator that can generate an oscillating signal applied to each of the one or more capacitive sensors; a capacitance-frequency converter circuit that can convert the frequency of the oscillating signal to the capacitance of each of the one or more capacitive sensors; and a call-answer circuit coupled to the capacitance-frequency converter circuit, wherein the call-answer circuit can be activated when the capacitance of the capacitive sensor changes by a predetermined amount or reaches a predetermined value when a user&#39;s hand moves to the proximity of the device body or touches the device body. 
     Implementations of the system may include one or more of the following. Each of the one or more capacitive sensors can change its capacitance when a user&#39;s hand is in the proximity of but not in touch with the device body. Each of the one or more capacitive sensors can change its capacitance when a user&#39;s hand is in touch with the device body. The device body can include a top case and a bottom case, wherein the single electrode of one of the one or more capacitive sensors is positioned between the top case and the lower case. The top case can include a display window and a keypad, wherein the single electrode has the form of a plate having openings under the display window and the keypad. The top case can include a display window and a keypad, wherein the single electrode is in the form of a plate and is positioned under the keypad. The mobile communication device can further include an answer button on the device body, wherein the call-answer circuit is coupled to the answer button and can be activated when the answer button is pressed. 
     In another general aspect, the present invention relates to a mobile communication device that includes a device body; one or more capacitive sensors each having a capacitance that varies depending on a user&#39;s hand position in the vicinity of the mobile communication device; an oscillator that can generate an oscillating signal applied to each of the one or more capacitive sensors; a capacitance-frequency converter circuit that can convert the frequency of the oscillating signal to the capacitance of each of the one or more capacitive sensors; a call-answer circuit coupled to the capacitance-frequency converter circuit; and a volume-control circuit coupled to the capacitance-frequency converter circuit, wherein the capacitance-frequency converter circuit can activate the call-answer circuit in response to a first position of the user&#39;s hand and to activate the volume-control circuit in response to a first position of the user&#39;s hand. 
     Implementations of the system may include one or more of the following. At least one of the one or more capacitive sensors can include a single electrode. At least one of the one or more capacitive sensors can change its capacitance when a user&#39;s hand is in the proximity of the device body or in touch with the device body. At least one of the one or more capacitive sensors can have a first capacitance when the user&#39;s hand is at the first position and a second capacitance when the user&#39;s hand is at the second position. The capacitance-frequency converter circuit can convert a first frequency of the oscillating signal to the first capacitance when the user&#39;s hand is at the first position, and wherein the capacitance-frequency converter circuit configured to convert a second frequency of the oscillating signal to the second capacitance when the user&#39;s hand is at the second position. The device body can include a top case and a bottom case, wherein the single electrode of one of the one or more capacitive sensors is positioned between the top case and the lower case. The top case can include a display window and a keypad, wherein the single electrode can have the form of a plate having openings under the display window and the keypad. The top case can include a display window and a keypad, wherein the single electrode can be in the form of a plate and is positioned under the keypad. 
     In another general aspect, the present invention relates to a mobile communication device which includes a device body; one or more capacitive sensors each having a single electrode that varies depending on a user&#39;s hand position in the vicinity of the mobile communication device; an oscillator that can generate an oscillating signal applied to each of the one or more capacitive sensors; and a capacitance-frequency converter circuit that can convert the frequency of the oscillating signal to the capacitance of each of the one or more capacitive sensor, wherein the capacitance-frequency converter circuit can activate a plurality of functions in response to different positions of the user&#39;s hand in the vicinity of the device body. 
     Implementations of the system may include one or more of the following. The plurality of functions can include call answering, volume control, volume silencing, or the turning on the vibration mode. The user&#39;s hand at different positions can change the capacitances of the one or more capacitive sensor by predetermined amounts or to predetermined values. The one or more capacitive sensor can change their respective capacitance when the user&#39;s hand is in the proximity of the device body or in touch with the device body. 
     Although the invention has been particularly shown and described with reference to multiple embodiments, it will be understood by persons skilled in the relevant art that various changes in form and details can be made therein without departing from the spirit and scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is an exploded perspective view of a mobile phone having a capacitor sensor in accordance with the present invention. 
         FIG. 2  is a detailed top view of the mobile phone shown in  FIG. 1 . 
         FIG. 3  illustrates a user&#39;s hand positioned in the proximity of the mobile phone shown in  FIGS. 1 and 2 . 
         FIG. 4  illustrates an exemplified sensing circuit for the capacitive proximity sensor compatible with the mobile phone shown in  FIGS. 1 and 2 . 
         FIGS. 5A and 5B  show the detection of a change in capacitance when a user&#39;s hand moves close to the mobile phone in accordance with the present invention. 
         FIG. 6  illustrates a user&#39;s hand touching the mobile phone shown in  FIGS. 1 and 2 . 
         FIG. 7  illustrates a user&#39;s hand holding the mobile phone shown in  FIGS. 1 and 2 . 
         FIG. 8  is a perspective exploded view of another mobile phone having a different capacitor sensor in accordance with the present invention. 
         FIG. 9  is a perspective exploded view of another mobile phone having a different capacitor sensor in accordance with the present invention. 
         FIG. 10  illustrates another exemplified sensing circuit for a capacitive sensor in a mobile phone in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 and 2 , a mobile phone  100  includes a top case  110 , a capacitive sensor  120 , and a bottom case  130 . The top case  110  can include microphone  111 , a speaker  112 , and a camera  113 . The top case  110  can also include a display window  114  and a keypad  115  that includes a call button  116  and a cancel button  117 . The top case  110  can also a wheel  118  for include a volume control. 
     The capacitive sensor  120  can be in the shape of plate frame comprising openings  124 ,  125  that are to be positioned under for the display window  114  and the key pad  115  in the top case  110 . The capacitive sensor  120  can be made of a conductive material such as a metal, an alloy, a conducting polymer, etc. The capacitive sensor  120  can operate as a capacitive proximity sensor ( 420  as shown in  FIGS. 4 and 5 ) and a capacitive touch sensor, as described below. 
     An important feature of the capacitive sensor  120  is that the capacitance of the capacitive sensor  120  is determined by a single electrode. The sensing circuit, as described below (e.g. in relation to  FIG. 9 ), can include a plurality of such single-electrode capacitive sensors, which allows flexibility in its configurations. The capacitive sensor  120  can take many different shapes and placed in different locations of the mobile phone  100 , for example, in the form a plate frame as shown in  FIG. 1  and in another shape and location as shown in  FIG. 8  below. 
     The bottom case  130  can include electronic circuit for controlling the operations (answer calls, display, sensors, clock, etc.) of the mobile phone  100 , which includes a circuit board  131  and a C-F converter integrated circuit (IC)  132  which enables the detection of a user&#39;s hand. The C-F converter integrated circuit (IC)  132  can be mounted on or separate from the circuit board  131 . The capacitive sensor  120  is connected to the C-F converter IC  132  by a connector wire  133 . The capacitive sensor  120  is separated from the other parts of the lower case  130  by an insulating material (not shown). 
     A user can answer an incoming call on the mobile phone  100  by pressing the call button  116 . In accordance with the present invention, the capacitive sensor  120  and associated sensing circuit (e.g.  400  in  FIG. 4 ) also allow a user to answer a call without pressing a button in the keypad  115 . As described in more detail below, a phone call be answered or another particular function can be activated on the mobile phone  100  by moving a hand in the vicinity of the mobile phone  100 , or touching the mobile phone  100 , or holding the mobile phone  100  in a specific position. 
     Capacitive Proximity Sensor 
     As shown in  FIG. 3 , when the mobile phone  100  receives an incoming call, a user can answer the incoming call moving her hand  300  toward the mobile phone  100 . When the capacitive proximity sensor  420  detects that the hand  300  is in the proximity, the mobile phone  100  can automatically switches to a voice input path to the speaker  112 , or other desired answering-mode. 
     Referring to  FIG. 4 , an exemplified sensing circuit  400  includes a capacitive proximity sensor  420  and a capacitance-to-frequency (C-F) converter IC  132  connected to the capacitive proximity sensor  420 . An oscillator  410  is configured to apply an oscillating signal to the capacitive proximity sensor  420 . The oscillator  410  can be internal or external to the sensing circuit  400 . Depends on the characteristics of the C-F converter IC  132 , the C-F converter IC  132  can be connected to passive components such as resistor  430 , a capacitor (not shown), a high voltage supply  440 , and the ground. A call answer circuit  450  in the circuit board  131  can receive input signals from and can be activated by the answer button  116  and the C-F converter IC  132 . A user can also press the answer button  116  to activate the call answer circuit  450 . 
     The capacitance of the capacitive proximity sensor  420  is dependent on the object in the vicinity around it (i.e. an electrode). When the user&#39;s hand moves to the vicinity of the mobile phone  100 , the air next to the capacitive proximity sensor  420  is replaced by the user&#39;s hand. The capacitive proximity sensor  420  can be calibrated to be most sensitive to human hand. The change in dielectric constant induced by the user&#39;s hand and the associated change in the capacitance in the capacitive proximity sensor  420  can be detected by the sensing circuit  400 , which is used to determine the presence of the user&#39;s hand. 
     In operation, an oscillating electric signal at a certain frequency is sent to the capacitive proximity sensor  420 , which produces an electromagnetic field around the single electrode of the capacitive proximity sensor  420 . When a user&#39;s hand is moved into the electromagnetic field around the capacitive proximity sensor  420 , the dielectric constant and thus the capacitance change, which in turn changes the frequency of the oscillating electric signal. The C-F converter IC  132  is configured to measure the frequency of the alternating electric signal in the sensing circuit, and convert the measured frequency to a capacitance value in the capacitive proximity sensor  420 . The conversion can be conducted using a pre-calibrated relationship between the oscillating frequency and capacitance of known object near or in touch of the mobile phone. 
     A change in the frequency can thus be used as an indicator for the presence of a user&#39;s hand in the proximity of the mobile phone  100 . A user&#39;s hand is determined to be in presence near the mobile phone  100  when the capacitance of the capacitive sensor changes by a predetermined amount or reaches a predetermined value. Once the user&#39;s hand is detected, the C-F converter IC  132  sends a control signal to the call answer circuit  450  to activate the call answer function. 
       FIGS. 5A and 5B  show the effects of the distance of a hand to the mobile phone  100 . In  FIG. 5A , the user&#39;s hand  500  is relatively far away from the capacitive proximity sensor  420  in the mobile phone  100 . The capacitive proximity sensor  420  is connected to the C-F converter IC  132  on the circuit board  131 . The capacitive proximity sensor  420  has a capacitance  510 , which results an oscillating electric signal  515  in the sensing circuit (e.g.  400 ,  FIG. 4 ). In  FIG. 5B , the user&#39;s hand  500  is moved to the vicinity of the capacitive proximity sensor  420 , which results in a capacitance  520  and an oscillating electric signal  525 . The capacitance  510  when the hand  500  is far away from the mobile phone  100  is much larger than the capacitance  520  when the hand is placed close to the mobile phone  100 . As a result, the oscillating electric signal  515  has a higher frequency than the frequency of the oscillating electric signal  525 . The C-F converter IC  132  can measure and convert the frequencies in the oscillating signals  515 ,  525  to capacitances  510 ,  520 . The absolute frequency value or a change in frequency can be used to determine the presence of the user&#39;s hand. The presence of the user&#39;s hand can be confirmed when the capacitance of the capacitive proximity sensor  420  changes by a predetermined amount or reaches a predetermined value. 
     Capacitive Touch Sensor 
     In some embodiments, the capacitor sensor can also operate as a touch sensor. As shown in  FIG. 6 , a mobile phone  600  includes a call button  603  and a cancel button  604 , as well as capacitive touch sensor (not visible) under the top case, similar to mobile phone  100  as shown in  FIGS. 1 and 2 . The capacitive touch sensor determines a touch state by detecting the change in capacitance, similar to the descriptions above in relation to  FIGS. 4 ,  5 A, and  5 B. When the mobile phone is not touched, the sensing circuit has a base capacitance contributed by the ground in the sensing circuit. When an incoming call is received by the mobile phone  600 , a user can touch the mobile phone  600  with his hand  602 . The total capacitance of the capacitive touch sensor increases, which leads to a decrease in the frequency of the oscillating signal in the sensing circuit. The C-F converter IC can measure the absolute frequency value or the change in frequency and calculate the change in the capacitance to recognize that the mobile phone  600  is touched the user&#39;s hand. 
     In some embodiments, the mobile phones (e.g.  100  in  FIGS. 1 and 2 ) in accordance with the present application can also identify the movement in a user&#39;s body. A user&#39;s movement, such as hand waving, can produce changes in capacitance in the capacitance sensor, and in turn in the frequency of the oscillating signal in the sensing circuit. If the change in the frequency matches the pattern of change corresponding to a hand waving movement, the mobile phone can recognize the pattern, and answers an incoming call or activate other actions in the mobile phone. 
     In some embodiments, the mobile phone in accordance with the present application can identify the specific position and/or orientation of a user&#39;s hand relative to the mobile phone. As shown in  FIG. 7 , a user&#39;s hand  702  is holding a mobile phone  100  which includes a capacitive sensor as described above. The mobile phone  100  measure the capacitance in the capacitive sensor by measuring the frequency of the oscillating signal in the sensing circuit. When the predetermined capacitance is identified, the mobile phone  100  can activate to call answering or other functions. 
     The capacitive sensor can include different layouts and configurations without deviating from the spirit of the present invention. For example, referring to  FIG. 8 , a mobile phone  800  includes a case  801  and a circuit board  803  under the case  801 . On the case  810  there is a key pad  802 . A C-F converter IC  804  and a single-electrode sensor plate  805  can be located on the circuit board  803 . The sensor plate  805  is located under the key pad  802  when the mobile phone  800  is assembled together. The C-F converter IC  804  is connected to the sensor plate  805  by a connecting wire  806 . 
     In another example, referring to  FIG. 9 , a mobile phone  900  includes a case  901  and a circuit board  903  under the case  901 . A key pad  902  is positioned on the case  910 . A C-F converter IC  904  can be located on the circuit board  903 . The mobile phone can include a plurality of sensors  905 A- 905 D at different locations. The C-F converter IC  904  is connected to the sensors  905 A- 905 D by connecting wire  906 . Each sensor  905 A- 905 D includes a single electrode for measuring its respective capacitance. The C-F converter IC  904  can determine the position of a hand relative to each of the sensors  905 A- 905 D. An oscillating signal is directed to each of the sensors  905 A- 905 D; the frequency of the oscillating signals are respectively measured and the capacitance of each of the sensors  905 A- 905 D computed by the C-F converter IC  904 . 
     As seen in  FIGS. 1-9  above, each capacitive proximity or capacitive touch sensor involves a single electrode in the sensing circuit. The mobile device can include a plurality of such sensors to determine a user&#39;s hand position. The sensor can be of a small size, flexible in shape and dimensions. These features allow significant flexibility in sensor designs. It should be noted that the disclosed mobile phones can switch on a different function from answering a phone call when the user&#39;s hand is detected in the proximity of or in touch with the phone&#39;s body. The different functions can include, for example, silencing the ring tone during a meeting, change the ring volume to a vibration mode, etc. Referring to  FIG. 10 , an exemplified sensing circuit  1000  includes a capacitive sensor  1020  and other similar components as the sensing circuit  400  as shown in  FIG. 4  and described above. The capacitive sensor  1020  can be a capacitive proximity sensor or a capacitive touch sensor. The C-F converter IC  132  can control the call answer circuit  450  as described above. In addition, the C-F converter IC  132  is connected to a volume control circuit  460 . The volume control circuit  460  can be controlled manually by dialing the wheel  118 . The volume control circuit  460  can also be controlled by the C-F converter IC  132  in response to the position of the user&#39; hand relative to the mobile phone. The volume control can include changing the volume of the speaker, silence the phone ring, and changing the phone to a vibration mode. The sensing circuit  1000  for example allows a user to hold a mobile phone in certain positions in his/her pocket to silence the mobile phone without looking at the phone or taking the phone out of the pocket. In accordance to the present invention, the sensing circuit  1000  can detect multiple of positions of a user&#39;s hand relative to the mobile phone. The different user&#39;s hand positions can produce different capacitances in the capacitive sensor and oscillating frequencies in the sensing circuit  1000 : for example, a first capacitance and a first oscillating frequency for call answering, and a second capacitance and a second oscillating frequency for volume adjustment. By distinguishing the different capacitance and oscillating frequencies as described above, the C-F converter IC  132  can initiate different functions on the mobile phone in response to different positions of the user&#39;s hand. 
     It is understood that the disclosed circuit and methods are compatible with other configurations of the electronic components and variations in circuit designs without deviation from the spirit of the present specification. The presently disclosed apparatus is applicable to different types of telecommunication devices that can receive calls, such as cell phones, cordless phone, family radio service (FRS), Walkie-talkie, etc. To answer a call, the disclosed device can be picked up, switched on, or connected by proximity detection or holding of the device without pressing any key or button. 
     An advantage of the presently disclosed mobile device is that each capacitive sensor does not require a pair of electrodes for detecting the capacitance between the two electrodes. As it is know, a pair of electrodes is restricted in design configurations (positions, size, and shape). The disclosed mobile devices therefore can simplify device design and construction, and reduce costs. 
     Furthermore, the sensing circuit disclosed above is intended to illustrate, and not to limit, the present invention. Many other circuit designs can achieve the described functions while still being compatible with the present invention. The capacitance of the capacitive sensor can also be measured in different manners. For example, different waveforms can be used in the oscillating sensing signals.