Abstract:
A battery saving method of controlling the display of a portable telephone is disclosed. The method comprises checking whether a user inputs a SEND key for a call origination to establish a call or an answering key in response to an incoming call; turning off the power supplied to the display when a call is set up according to the SEND key or the answering key; and, turning on the power supplied to the display when the call is terminated. Further, the display is turned off after a predetermined period of time has elapsed after the SEND key or the answering key is activated.

Description:
CLAIM OF PRIORITY 
   This application makes reference to and claims all benefits accruing under 35 U.S.C. Section 119 from an application entitled “Method for Saving Battery by Controlling Display in Portable Telephone” filed in the Korean Industrial Property Office on Jul. 21, 1999 and there duly assigned Serial No. 99-29511. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to a portable telephone, and more particularly, to a method for saving battery power consumption by turning off the display unit of the portable telephone during a call connection. 
   2. Description of the Related Art 
   If the battery of a portable telephone has to be replaced frequently, it imposes a significant limitation on the usage of the portable telephone. Thus, it is desirable to provide a portable telephone with longer usage time by a given battery. Accordingly, the technology has evolved to contrive new novel batteries that are superior and have a longer lasting lifetime. In addition to the development of the battery technology, many studies have been made on various methods of saving battery power by minimizing power consumption of the portable telephone. 
   Normally, a user holds the portable telephone to his/her ear during a call connection. Although the user does not pay attention to the display unit of the portable telephone during the conversation, the display unit is turned on in the existing portable telephone. In such a case, the display unit unnecessarily consumes the battery power even though the user does not and can not watch the display unit of the portable telephone during the call connection. 
   SUMMARY OF THE INVENTION 
   It is, therefore, an object of the present invention to provide a method for saving a battery lifetime by controlling the display of a portable telephone in which the display is turned off during a call in order to prevent unnecessary power consumption. 
   To achieve the above object of the present invention, there is provided a battery saving method of controlling the display unit of a portable telephone. The method comprises checking whether a user inputs a SEND key for a call origination or an answering key in response to an incoming call; turning off the display when a call is set up according to the activation of the SEND key or the answering key; and, turning on the display when the call is terminated. 
   According to one aspect of the invention, the display is turned off when a predetermined period of time has elapsed after the activation of the SEND key or the answering key. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which: 
       FIG. 1  is a block diagram illustrating a portable telephone according to the embodiment of the present invention; 
       FIG. 2  is a flow chart illustrating a procedure for controlling the operation of an LCD during a call origination according to the embodiment of the present invention; and, 
       FIG. 3  is a flow chart illustrating a procedure for controlling the operation of the LCD during a call termination according to the embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. For the purpose of clarity, well-known functions or constructions are not described in detail as they would obscure the invention in unnecessary detail. 
     FIG. 1  shows a block diagram of a portable telephone according to the embodiment of the present invention. With reference to  FIG. 1 , a controller  111  controls the entire operation of the portable telephone, specifically the operating voltage supplied to the display unit according to the embodiment of the present invention. A duplexer  112  receives a radio signal from an antenna ANT and provides the received radio signal to a radio receiver  113 . Similarly, the duplexer  112  transmits a transmission signal received from a radio transmitter  115  via the antenna ANT. The radio receiver  113  provides input data to the controller  111  during a data communication mode and provides an input audio signal to a voice processor  116  during a conversation mode. A frequency synthesizer  114  generates a local oscillation signal for demodulating the received signal under the control of the controller  111 . Also, the frequency synthesizer  114  generates a transmission carrier signal and provides the generated transmission carrier signal to the radio transmitter  115 . The radio transmitter  115  mixes the sound signal received from the voice processor  116  with the carrier signal received from the frequency synthesizer  114  and outputs the mixed signals to the duplexer  112  under the control of the controller  111  during the conversation mode. The voice processor  116  demodulates the coded audio signal received from the radio receiver  113  and outputs the demodulated audio signal to a speaker SPK via a switch  117 . Also, the voice processor  116  receives the electrical audio signal from a microphone MIC via the switch  117 , encodes the electrical audio signal, and outputs the coded audio signal to the radio transmitter  115 . 
   A ringer  118  generates a ring tone upon receiving a ring signal under the control of the controller  111 . A memory  119  stores the control program of the controller  111 . The memory  119  includes a Read Only Memory (ROM) for storing various programs, a Non-Volatile Memory (NVM) for storing telephone numbers and names, and a Random Access Memory (RAM) for temporarily storing data generated during the execution of the programs. 
   A key input device  121 , a key matrix, has numeric keys for dialing and contains various functional keys. The key input device  121  generates a key input signal corresponding to the key selected by a user and provides the generated key input signal to the controller  111 . A display  130  includes a Liquid Crystal Display (LCD)  131  and a back light  133 . The display  130  displays the operating status of the portable telephone and is turned on/off under the control of the controller  111 . 
     FIG. 2  shows a procedure for controlling the operation of the LCD during a call origination according to the embodiment of the present invention, and  FIG. 3  shows a procedure for controlling the operation of the LCD during a call termination according to the embodiment of the present invention. 
   First, with reference to  FIG. 2 , a detailed description will be made as to how to control the LCD power of the portable telephone during a call origination according to the present invention. 
   Upon having the power-on in step  201 , the controller  111  turns on the LCD  131  while the back light  133  of the display  130  is turned off in step  203 . During the on-state, the LCD  131  and the back light  133  are provided with the operating voltage from a battery (not shown), whereas during the off-state, the LCD  131  and the back light  133  are not provided with the operating voltage from the battery. 
   Then, the controller  111  checks in step  205  whether the user inputs (or presses) a SEND key for a call origination using the key input device  121 . When the SEND key is inputted, the controller  111  turns on the back light  133  for a predetermined period of time and maintains the on-state of the LCD  131 . Otherwise, when the SEND key is not inputted, the controller  111  returns to step  203  to maintain the on-state of the LCD  131  and the off-state of the back light  133 . 
   After step  205 , the controller  111  checks, in step  207 , whether a call is set up or not. When the call is set up, the controller  111  proceeds to step  213 . Alternatively, the controller  111  may proceed to steps  209  and  211  prior to proceeding to step  213 . In step  209 , the controller  111  checks whether a predetermined period of time has elapsed. If it is determined in step  211  that the predetermined period of time has elapsed, the controller  111  proceeds to step  213 . Here, the predetermined period of time is defined as a time period required for the user to hold his/her portable telephone to his/her ear after dialing the phone number to make a call. In a normal usage behavior, a portable phone user presses the SEND key for a call origination then holds the portable telephone to his/her ear waiting for the call connection with the receiving party. Thus, the time required for this operation is arbitrarily determined. 
   Thereafter, in step  213 , the controller  111  cuts off the operating voltage supplied to the LCD  131  and the back light  133  in order to turn off the LCD  131  and the back light  133 . This is done to save the battery power by reducing the power consumption that is unnecessary to drive the display  130  during a conversation as the portable telephone is held to the user&#39;s ear that is out of the user&#39;s sight and the user does not and can not pay attention to the display  130 . 
   When the user ends the call by pressing the END key in step  215  during which the display  130  is turned off, the controller  111  turns back the power supplied to the LCD  131  but maintains the turn-off state of the back light  133  in step  217 . 
   Next, a detailed description will be made as to how to control the LCD power during a call termination with reference to  FIG. 3 . 
   Upon turning the power-on in step  301 , the controller  111  turns on the LCD  131  and turns off the back light  133  of the display  130  in step  303 . Then, the controller  111  checks in step  305  whether a ring signal for call termination is received. Upon detection of the ring signal, the controller  111  turns on the back light  133  for a predetermined period of time and maintains the on-state of the LCD  131 , in step  307 . At the same time, the controller  111  raises a call termination alarm. Otherwise, if the ring signal is not detected, the controller  111  returns to step  303  to maintain the on-state of the LCD  131  and the off-state of the back light  133 . 
   After step  307 , the controller  111  checks in step  309  whether the user inputs a call answering key using the key input device  121  or other mechanism to receive the incoming call. When the call answering key is inputted, the controller  111  proceeds to step  315 . Alternatively, the controller  111  may proceed to steps  311  and  313  prior to step  315 . In step  311 , the controller  111  checks whether a predetermined period of time has elapsed. If it is determined in step  313  that the predetermined period of time has elapsed, the controller  111  proceeds to step  315 . Here, the predetermined period of time is defined as a time period required for the user to hold the portable telephone to his/her ear to receive an incoming call. Normally, the user activates the ANSWER key or other equivalent mechanism to receive a call termination then hold the portable telephone to his/her ear. Here, the time required for this operation is arbitrarily determined. 
   In step  315 , the controller  111  cuts off the operating voltage supplied to the LCD  131  and the back light  133  in order to turn off the LCD  131  and the back light  133 . This is done to save battery power by reducing the power consumption that is unnecessary to drive the display  130  as the portable telephone is held to the user&#39;s ear during the call and the user can not pay attention to the display  130  of the portable telephone. 
   When the user ends the call by pressing the END key in step  317 , during which the display  130  is turned off, the controller  111  turns on the LCD  131  but maintains the turn-off state of the back light  133 , in step  319 . 
   The invention has been described with reference to the embodiment in which the operating voltage of the LCD  131  and the back light  133  are controlled during the call. However, when using an ear-microphone or a speaker phone, the portable telephone may continuously provide the operating voltage to the LCD  131  during the call. 
   As described above, the present invention gives an advantage of saving the battery power by cutting off the operating voltage supplied to the display when not in use during the call. While the invention has been shown and described with reference to a certain preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and the scope of the invention as defined by the appended claims.