Abstract:
A terminal with a keypad enables a user to input an alphabet character through the keypad at high speed without modification of the keypad. The terminal comprises receiving a first input character in an alphabet input mode; waiting for a key input for at least one second input character succeeding the first input character; upon receiving a key input for the second input character, searching for a priority table in which a displaying order of a succeeding alphabet character is designated; and controlling a displaying order of the second input character according to the priority table.

Description:
PRIORITY 
     This application claims the benefit under 35 U.S.C. §119(a) to an application entitled “Method and Apparatus for Inputting Alphabet Character in a Terminal with a Keypad” filed in the Korean Intellectual Property Office on Jul. 13, 2004 and assigned Ser. No. 2004-54434, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a key input method and apparatus in a terminal with a keypad. In particular, the present invention relates to a method and apparatus for inputting alphabet characters. 
     2. Description of the Related Art 
     In general, a mobile terminal refers to a device designed such that an individual can carry it and transmit/receive voice and data regardless of time and place. The mobile terminal is classified into a work analysis program (WAP) phone, a personal digital assistance (PDA), a web pad, and the like and is commonly used by an increasing number of people due to its ability to provide personal service-based mobility. With the development of communication technology, the mobile terminal is used not only for voice communication but also image communication. Due to the rapid progress of mobile communication technology, service providers or mobile carriers provide users with additional services in addition to the basic mobile terminal&#39;s functions of processing calls and guaranteeing the quality of the calls. For example, the additional services include a voice information service for providing users with news, sports, stock, and weather information, a traffic information service for providing users with traffic information, and a communication service such as Internet access, fax and e-mail services. In addition to the foregoing services, an increasing number of mobile terminal users are enjoying text and voice services. 
     In most cases, to enjoy such services, a user of the mobile terminal inputs characters using a keypad mounted on the mobile terminal. For example, to transmit a short message service (SMS) message, store phone numbers in a phone book, and transmit an e-mail via wireless Internet using the mobile terminal, the user inputs corresponding characters using the keypad. A description will now be made regarding how the user inputs alphabet characters through the existing keypad used for the mobile terminal. 
       FIG. 1  is a diagram illustrating a layout of a conventional keypad for a mobile terminal. As illustrated in  FIG. 1 , the keypad includes buttons arranged in 4 rows and 3 columns, and numbers, alphabet characters and special characters are mapped to the buttons. In one of a number mode, an alphabet character mode, and a special character mode, if the buttons are pressed, numbers or characters mapped to the pressed buttons are input. Referring to  FIG. 1 , in each button, a number is written in the center, and possible alphabet characters of, for example, QZ, ABC, GHI, . . . , WXY, are written under the number. As illustrated, 3 alphabet characters are allocated to most of the buttons with a number written thereon. To input a word using the keypad of  FIG. 1 , the user should press buttons corresponding to alphabets comprising the word a predetermined number of times as shown in Table 1. 
     
       
         
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 No. of button 
                   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 presses 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
               
               
                   
               
             
             
               
                 1 
                 Q 
                 A 
                 D 
                 G 
                 J 
                 M 
                 P 
                 T 
                 W 
               
               
                 2 
                 Z 
                 B 
                 E 
                 H 
                 K 
                 N 
                 R 
                 U 
                 X 
               
               
                 3 
                   
                 C 
                 F 
                 I 
                 L 
                 O 
                 S 
                 V 
                 Y 
               
               
                   
               
             
          
         
       
     
     It will be assumed herein that the user inputs a word “LOVE” through the conventional keypad of  FIG. 1 . Referring to Table 1, the user should press a button with a number ‘5’ three times to input ‘L’, a button with a number ‘6’ three times to input ‘O’, a button with a number ‘8’ three times to input ‘V’, and a button with a number ‘3’ two times to input ‘E’. 
     The conventional keypad does not fully consider the convenience of the user and requires the user to press the same button several times in order to input a word. Therefore, the user feels inconvenienced especially when inputting frequently used words. For this reason, English-speaking users feel inconvenienced by the alphabet character input method because their body structure does not match well with the structure of the conventional keypad. To solve this problem, the alphabets of the conventional keypad should be appropriately rearranged. However, it is difficult to change a structure and design of products that have already been put on the market. In addition, because English-speaking users have become accustomed to the structure of the conventional keypad, it is not preferable to change the structure of the keypad. If a device for displaying all of the words starting with characters input by the user based on words in an English dictionary in the mobile terminal to solve the problems, the required memory capacity increases and the power required for outputting a specific word also increases, placing restrictions on the implementation. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide a method and apparatus for inputting alphabet characters with a reduced number of button presses in a terminal. 
     According to one aspect of the present invention, there is provided a method for inputting an alphabet character in a terminal with a keypad. The method comprises the steps of receiving a first input character in an alphabet input mode; waiting for a key input for at least one second input character succeeding the first input character; upon receiving a key input for the second input character, searching for a priority table in which a displaying order of a succeeding alphabet character is designated; and controlling a displaying order of the second input character according to the priority table. 
     According to another aspect of the present invention, there is provided an apparatus for inputting an alphabet character in a terminal with a keypad. The apparatus comprises a memory for storing various characters input through the keypad, and storing a predetermined priority table in which a displaying order of at least one alphabet character succeeding a first input alphabet character is designated; a display for visually displaying the alphabet character; and a controller for searching for the priority table corresponding to a just previously input alphabet character if there is any key input for the succeeding alphabet character, and outputting the succeeding alphabet character to the display according to the priority table. 
    
    
     
       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 diagram illustrating a layout of a conventional keypad for a mobile terminal; 
         FIG. 2  is a block diagram illustrating a structure of a mobile terminal according to an embodiment of the present invention; 
         FIGS. 3A and 3B  are flowcharts for a description of a method for displaying an alphabet character depending on a signal input through a keypad according to an embodiment of the present invention; and 
         FIGS. 4A to 4C  are diagrams illustrating frequencies of words calculated according to an embodiment of the present invention. 
     
    
    
     Throughout the drawings, the same or similar elements, features and structures are represented by the same reference numerals. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Several embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein has been omitted for conciseness. 
     Although the method and apparatus for inputting alphabet characters according to an embodiment of the present invention can be applied to every device with a keypad, it will be assumed herein as an example that the method and apparatus is applied to a mobile terminal with a keypad. 
       FIG. 2  is a block diagram illustrating a structure of a mobile terminal according to an embodiment of the present invention. A keypad  200 , a device for interfacing with a user, comprises various function keys, a Send key, and a plurality of keys for inputting characters. A number, a character, and a special character mapped to each of the keys arranged on the keypad  200  are matched to a controller  204  via a keypad interface  202 . The controller  204  controls the overall operation of the mobile terminal. According to an embodiment of the present invention, in an alphabet input mode, the controller  204  controls not only the function of inputting, by a user, a short message service (SMS) message, a phone number, a schedule, a memorandum, and the other information, but also a chatting function and a function of transmitting an e-mail, using the keypad  200 . Further, the controller  204  has a function of outputting status information indicating arrival of an SMS message and a dialing state to a display  206 . In addition, the controller  204  can display, on the display  206 , the general operational state or status such as the current time, reception sensitivity, and a remaining battery life. 
     The display  206  visually displays various signals output from the controller  204 , and can be implemented with a liquid crystal display (LCD). In this case, the display  206  can comprise a LCD controller, a memory for storing image data, and a LCD panel. 
     A memory  208  can comprise a read only memory (ROM) and a random access memory (RAM). The memory  208  stores various temporal data generated in the processing process of the controller  204 , and user data such as phone numbers, bell sounds, and image information. In addition, the memory  208  can store a program for controlling a general operation of the mobile terminal and a predetermined program for controlling signals generated by pressing a key on the keypad  200  by the user according to an embodiment of the present invention. Further, the memory  208  stores a priority table, in an embodiment of the present invention, for reducing the number of key presses in the process of inputting alphabet characters. The priority table refers to a table created by taking into account priority of a previously input alphabet, unlike the conventional way of displaying an alphabet corresponding to the number of keys presses for each of the keys on the keypad shown in  FIG. 1 . A detailed description of the priority table will be given later. 
     A data processor  210  comprises a receiver for demodulating and decoding received signals, and a transmitter for modulating and encoding transmission signals. That is, the data processor  210  can comprise a modem and a codec. The codec reproduces reception audio signals, output from a data codec for processing packet data and an audio codec for processing audio signals, or transmits transmission audio signals generated from a microphone to the audio codec of the data processor  210 . In addition, the data processor  210  processes voice signals, received from the controller  204 , for indicating information on another program in operation and the execution result. 
     A radio frequency (RF) unit  212  comprises a RF transmitter (not shown) for frequency-up-converting transmission signals and amplifying the frequency-up-converted transmission signals, and a RF receiver (not shown) for low-noise-amplifying received signals and frequency-down-converting the low-noise-amplified signals. 
       FIGS. 3A and 3B  are flowcharts of a method for displaying an alphabet character depending on a signal input through a keypad according to an embodiment of the present invention. Referring to  FIGS. 3A and 3B , in step  300 , a controller  204  determines whether a current input mode is set to an alphabet input mode. The alphabet input mode refers to an input mode in which an alphabet input operation is needed to write a SMS message or store an address. If the current input mode is set to the alphabet input mode, the controller  204  proceeds to step  302  where it determines if a character has been input. If no character has been input, the controller  204  waits until an alphabet is input. 
     If it is determined in step  302  that a character has been input through a keypad  200 , the controller  204  proceeds to step  304  where it displays on a display  206  a character corresponding to the number of key presses for a corresponding key on the keypad. In step  304 , the controller  204  may comprise a process of determining whether the character first input in step  302  is an alphabet character. The controller  204  determines whether the first character is an alphabet character in order to process the step according to a user of the mobile terminal, or if a special character, such as *, ?, and !, is input. The controller  204  can either input the special character according to the user, or transition to a wait mode to re-receive an input, if the input special character is an incorrect input. 
     In step  304 , if the first input is an alphabet character, the controller  204  displays an alphabet character corresponding to the number of key presses of a key on the keypad, and then proceeds to step  306  where it stores the alphabet in a memory  208 . After storing the alphabet in the memory  208 , the controller  204  determines in step  308  whether there is a succeeding alphabet input according to the key pressed on the keypad. If there is a succeeding alphabet character input, the controller  204  proceeds to step  310  where it searches the memory  208  for a priority table corresponding to a previously input alphabet character. However, if it is determined in step  308  that there is no succeeding alphabet character input, the controller  204  determines in step  316  whether there is a key input corresponding to an end of inputting a word. For example, the key corresponding to an end of inputting a word can be a space key corresponding to an end of inputting one word. For convenience, a previously input alphabet character will be referred to as a “first input character,” and a succeeding input alphabet character will be referred to as a “second input character.” 
     The controller  204  searches for a priority table corresponding to the first input character in step  310 , and displays on the display  206  a character corresponding to the number of button presses for the corresponding button according to the priority table in step  312 . The controller  204  stores the alphabet displayed on the display  206  in the memory  208  in step  314 . After storing the alphabet, the controller  204  determines in step  316  whether any key input corresponds to an end of inputting a word. The key corresponding to an end of inputting a word can be a space key corresponding to an end of inputting one word. 
     If it is determined in step  316  that there is a key input corresponding to an end of inputting a word, the controller  204  returns to step  302  to determine whether there is any key input indicating an input of a new word. 
     If it is determined in step  316  that there is no key input corresponding to an end of inputting a word, the controller  204  determines in step  318  whether there is any key input corresponding to an end of inputting an English sentence. If there is a key input corresponding to an end of inputting an English sentence, the controller  204  proceeds to step  320  where it stores the input English sentence in the memory  208  as an SMS message and then releases the alphabet input mode. If it is determined in step  318  that there is no key input corresponding to an end of inputting an English sentence, the controller  204  determines in step  322  whether there is any key input corresponding to a change in the input mode. The key input corresponding to a change in the input mode comprises an input of a function key or a special key for performing a predetermined operation according to a corresponding key press, and an input of a setting key for inputting other characters. 
     If it is determined in step  322  that there is a key input corresponding to a change in the input mode, the controller  204  performs an operation of the changed mode according to the corresponding input mode in step  324 . However, if there is no key input corresponding to a change in the input mode, the controller  204  determines in step  326  whether there is any succeeding alphabet input. If there is a succeeding alphabet input, the controller  204  returns to step  310  where it searches the memory  208  for a priority table corresponding to the first input character. 
     An embodiment of the present invention will now be described with reference to  FIGS. 2 ,  3 A and  3 B.  FIGS. 4A to 4C  illustrate frequency of words in a table format, calculated for actual application of the present invention. Information regarding the frequency of words is stored in the memory  208  of  FIG. 2 .  FIGS. 4A to 4C  illustrate tables measured for 12000-word sentences related to a newspaper, article, journal, music, and novel having words with a high frequency of use. In  FIGS. 4A to 4C , an alphabet in “&lt;&gt;” represents the first input character, and the number of 1 to 9represents each of the number keys mounted on the keypad  200  included in the mobile terminal and represents a number key on the keypad  200 , pressed to input the second input character. 
     More specifically, “&lt;a&gt;” indicates a first input character. An alphabet corresponds to a number of 1 to 9 and a number beside a colon represents priority of the alphabet based on frequency of occurrence of the corresponding alphabet with the first input character. The greater the number indicates the higher priority. 
     With reference to  FIGS. 4A to 4C , a description will now be made of a comparison between the embodiment of the present invention and the conventional method of Table 1 in terms of the number of key strokes. 
     Conventionally, to input a sentence “I LOVE YOU” using Table 1, the user should press a key with a number ‘4’ three times to input “I,” a key with a number ‘5’ three times to input “L,” a key with a number ‘6’ three times to input “O,” a key with a number ‘8’ three times to input “V, ” a key with a number ‘3’ two times to input “E,” a key with a number ‘9’ three times to input “Y,” a key with a number ‘6’ three times to input “O,” and a key with a number ‘8’ two times to input “U,” amounting to a total of 22 key strokes. 
     However, in the embodiment of the present invention, referring to  FIGS. 4A to 4C , the user presses the key with a number ‘4’ three times to input “I,” the key with a number ‘5’ three times to input “L,” the key with a number ‘6’ once to input “O,” the key with a number ‘8’ three times to input “V,” the key with a number ‘3’ once to input “E,” the key with a number ‘9’ three times to input “Y,” the key with a number ‘6’ once to input “O,” and the key with a number ‘8’ once to input “U,” amounting to a total of 14 key strokes, which is less than that of the conventional method by 8 strokes. 
     Table 2 illustrates a comparison between the proposed character input method and the conventional character input method for other sentences. 
     
       
         
               
               
             
               
               
               
             
               
               
               
             
           
               
                   
                 TABLE 2 
               
             
             
               
                   
                   
               
               
                   
                 Number of key strokes 
               
             
          
           
               
                   
                 Conventional Method 
                 Inventive Method 
               
               
                   
                   
               
             
          
           
               
                 I LOVE YOU 
                 22 
                 14 
               
               
                 YOU MUST GO HOME 
                 27 
                 18 
               
               
                 MICHAEL JACKSON 
                 30 
                 16 
               
               
                   
               
             
          
         
       
     
     It can be understood from Table 2 that the alphabet input method in accordance with an embodiment of the present invention is much less than the conventional alphabet input method in terms of the number of key strokes. 
     Although the embodiment of the present invention is applied herein to a mobile terminal with a keypad, it can also be applied to every device with a keypad. 
     As can be understood from the foregoing description, in the mobile terminal with a keypad, the alphabet input method in accordance with an embodiment of the present invention can decrease the number of key strokes compared with the conventional alphabet input method without a change in the structure of the keypad. In addition, compared with the device for displaying all of the words starting with characters input by the user based on an English dictionary, the device with a keypad can be implemented with the low memory capacity and the low power consumption in accordance with an embodiment of the present invention. 
     While the invention has been shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.