Patent Publication Number: US-5297247-A

Title: Display device

Description:
This application is a continuation of application Ser. No. 07/617,388, filed Nov. 19, 1990, now abandoned, which is a continuation of application Ser. No. 07/216,396, filed Jul. 7, 1988, now abandoned. 
    
    
     This pocketable display device for displaying characters or graphic images received by radio. It relates particularly, but not exclusively to non-alphanumeric (English) languages, i.e. general pictographic, written languages including Oriental languages such as the Chinese language and to a radio paging device for use with such languages. 
     It is known to be extremely difficult to implement a pager receiver for pictographic Oriental languages for the following two reasons: 
     a) Most Oriental languages have a huge number of characters or pictograms as compared to English style European languages. In particular, the Chinese language is composed of more than 50,000 different characters. Therefore, without the invention of a special storage technique, it would be impossible to accommodate such a large vocabulary in any form of storage device which would enable the pager to have a size comparable with the size of a pack of 20 cigarettes. This is essential for a pocket radio pager receiver. 
     b) Normally, longer air-time (which is a valuable factor in the paging business) is required to transmit a character of an Oriental language than a usual alphanumeric character due to the large number of characters which require a longer code to identify individual characters. Unless a special message recognition technique can be devised and built into the radio pager receiver, an Oriental language radio pager receiver will be too expensive in terms on running cost for its air-time message transmission. 
     At present, there are, of course, numerous radio pager receivers which can provide the user with information in English and alphanumeric characters. There still does not exist a radio pager receiver which can receive and display the Oriental languages; in particular for the Chinese language by overcoming the above mentioned problems. The usefulness and attractiveness of information display pagers would be enhanced considerably by the provision of a pager, capable of displaying greater amount of information to the users in different Oriental languages especially in the most popular Chinese language. 
     A further problem with current pagers is that they have an &#34;Identification Code&#34; (ID) which has been written and fixed permanently into a piece of Read Only Memory, called a code plug to enable the paging company to address individual pager receivers. It would be much more cost effective and convenient to have a pager which uses no code plug but another innovative concept to signify its own identification. At the moment, any change of the pager number (i.e. ID) requires the replacement of the physical code plug, which may involve the pager being taken back to the paging station physically. 
     According to a first aspect of the invention, there is provided a display device for displaying alphanumeric and/or pictographic characters such as of an Oriental language including Chinese, Korean and Thai and/or graphic information comprising: 
     radio receiving circuitry for receiving a radio message in which is encoded characters and/or graphic images to be displayed; 
     at least one display for displaying the received as such characters and/or as a graphic image: and 
     processing circuitry for receiving the radio message as N-bit message data words from the receiving circuitry, the processing circuitry being operative to convert the data words into displayed characters and/or graphic images in a manner such as to extend the total number of displayable characters and/or graphic images beyond 2 N  (2 raised to the power N) by using at least one of the 2 N  possible data words to alter the conversion used to generate the characters and/or usage. 
     A second aspect of the invention provides a display device comprising: 
     radio receiving circuitry for receiving a radio message; 
     at least one display for displaying the received radio message as such characters and/or as a graphic image; and 
     processing circuitry for converting data words of the received message into displayed characters and/or graphic images; 
     means for storing, between the receipt of radio messages by the radio receiving circuitry, the value of at least one parameter used by circuitry of the device for defining a characteristic of its operation; 
     and means responsive to at least one command encoded in a received message to set at least one such parameter to a required value. 
     These aspects of the invention are applicable to a display device, particularly a radio paging device independently of one another or in combination with one another. 
     As will become apparent from the following description, the two aspects of the invention may be used to solve the above mentioned problems, and when used together, may provide a pager which can receive and display any type of Oriental languages, in particular, the Chinese language and which requires no code plug but yet can still be addressed by the paging company individually. By using a custom made &#34;Single Chip Microprocessor Application Specific Integrated Circuit (ASIC)&#34; controller loaded with a special designed software program, the radio pager receiver can have the capability to store the message data collected by an electronics data reception module via a radio frequency channel into a random access memory device-RAM, and at the same time through searching from a character fonts table residing partly in a character generation read only memory-ROM and partly in a read/write memory-RAM by executing an innovative floating storage technique (to be described later) to display the message received on a graphic LCD module and a dynamic identification (to be described later) concept to identify a particular pager receiver among all receivers. 
     The radio pager receiver itself can store up multiple messages for the user to examine later. The control means of the pager can be arranged to enable the displayed messages to be viewed one by one either in the forward or reverse directions and when it reaches the end, it will display the first message again, the second message and so forth again. It also enables each message, if too long, to be displayed frame by frame (i.e. one display&#39;s worth at a time). The user can also select messages to be deleted from the memory. The control means can also enable the user to switch on/off the LCD display background lighting, and switch off the audio tone upon receipt of a message. 
     The first aspect of the invention enables implementation of the above mentioned floating storage technique (FST) which is an innovative idea by using an optimum number of bits to address a unique entry from a fixed size character fonts table which has the capability to cover an unlimited number of characters or pictograms. This can be explained as follows: 
     Let it be assumed that &#34;N&#34; bits are used to represent an address code representing one character of, for example, an Oriental language. An N-bit code can normally address a maximum of &#34;2 to the power N&#34; entries, each code corresponding to a respective character. The FST involves different usages of the 2 N  total number of available codes along the lines of the following. In particular, it may divide the 2 N  codes into 4 usages: 
     
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Usage 1 &#34;X&#34; combinations                                                  
                      to address &#34;X&#34; fixed                                
                      entries with a character                            
                      font table residing in                              
                      read only memory (ROM).                             
Usage 2 &#34;Y&#34; combinations                                                  
                      to address &#34;Y&#34; fixed                                
                      entries with the                                    
                      character font table                                
                      residing in RAM which can                           
                      be altered via the system                           
                      controller through                                  
                      receiving a command from                            
                      the radio frequency                                 
                      channel.                                            
Usage 3 &#34;Z&#34; combinations                                                  
                      to address &#34;phrases&#34;                                
                      composed of a number of                             
                      pointers to cascade a                               
                      sequence of single                                  
                      character entries within                            
                      the fixed vocabulary from                           
                      table &#34;X&#34; and &#34;Y&#34;. These                            
                      pointer sequences are                               
                      located also in RAM which                           
                      can be altered by the                               
                      system controller through                           
                      receipt of a command from                           
                      the radio frequency                                 
                      channel.                                            
Usage 4 &#34;1&#34; combinations                                                  
                      in case the required                                
                      character font does not                             
                      exist in the &#34;X&#34; and &#34; Y&#34;                           
                      table or the display of                             
                      some graphic is required,                           
                      this specific address                               
                      code can instruct the                               
                      system to construct the                             
                      required graphic or                                 
                      character fonts from the                            
                      direct bit pattern data                             
                      received from the radio                             
                      frequency channel; the                              
                      end of the bit pattern                              
                      can be indicated in any                             
                      suitable way, eg, by a                              
                      bit pattern following it                            
                      (such as the bit pattern                            
                      indicating the start of                             
                      usage 4) or by a preamble                           
                      which indicates the                                 
                      lengths, width and                                  
                      coordinates of the image                            
                      being sent.                                         
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     It is obvious that the sum of &#34;X&#34;, &#34;Y&#34;, &#34;Z&#34; and 1 will still equal to 2 N . However, this technique offers the following unique advantages over other methods being used: 
     Usage 1 can be used to hold the most frequently used characters/pictograms, in the language in question for efficient and fast processing and translation. 
     Usage 2 can be used to expand the system&#39;s capability to recognise the whole character/pictogram set of that particular language without any pre-set limit. 
     USage 3 enables the use of just &#34;N&#34; bits to represent a frequently used phrase which might comprise a string of any length of characters or pictograms. This represents a considerable saving of data space and licence transmission time; the transmission time for message transmission is the most expensive and important element in the paging industry. 
     Usage 4 further expands the system to recognise information more than text messages, but to any form of graphic information. In the paging business, it makes the pager receiver become a small facsimile receiver. 
     As an example of applying the FST to the Chinese language in particular to the radio pager receiver application, we found from statistics that by appropriately selecting them, the fixed 4,000 characters can cover over 99% of the vocabulary used in the paging industry. Therefore, it is possible to use a unique 12 bits (one and half byte) address to identify a character font entry. In other words, 
     
         ______________________________________                                    
Where &#34;N&#34; = 12 bits and                                                   
&#34;X&#34; = 4,000 combinations                                                  
                   to address total 4,000                                 
                   fixed characters font                                  
                   residing in a 128K × 8                           
                   bits ROM.                                              
&#34;Y&#34; = 32 combinations                                                     
                   to address a total of 32                               
                   programmable characters                                
                   from a font residing in                                
                   part of the 8K × 8 bits                          
                   RAM.                                                   
&#34;Z&#34; = 63 combinations                                                     
                   to address a total of 63                               
                   programmable phrases                                   
                   residing in part of the                                
                   8K × 8 bits RAM.                                 
&#34;1&#34; = 1 combination                                                       
                   to address general                                     
                   graphic information.                                   
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     The second aspect of the invention can be used to avoid having to change the ID ROM to alter the pager ID. The paging company simply sends a command through wireless transmission to the pager to achieve the same result. The removal of the code plug will also save some space so the pager can be made smaller. Thus, this aspect of the invention provides a dynamic identification (DI) technique whereby the pager&#39;s identification code (ID) is stored in a portion of the message RAM which is non-volatile, e.g. by being backed up by a 10 year life lithium battery, instead of being stored in ROM. Through intelligent control by a custom microcontroller, this identification code is no longer pre-fixed but can be changed easily under authorisation of the paging company to simply issue a command to the receiver via the radio frequency channel. In addition, more than one identification code for different purposes of application can be stored simultaneously which makes different categories of news broadcasting to a particular group of subscribers easy and cost effective. 
     The term &#34;radio paging device&#34; as used in the present description and claims is not intended to be limited to a device dedicated solely to that purpose but is intended to include all devices which provide that function in a personally portable form. In particular, apart from its implementation as a dedicated device, the invention may also be put into effect by providing an accessory, attachment or insert to a personally portable electronic device having a suitable display and effective to receive radio paging transmissions and display them on that display. 
    
    
     The invention will be further described by way of non-limitative example with reference to the accompanying drawings in which: 
     FIG. 1 is a block diagram illustrating the circuitry of a pager in accordance with the invention; and 
     FIG. 2 shows how the different sub-modules are assembled together to form a complete radio pager receiver unit. 
    
    
     The pager illustrated in the attached figures comprises a pocketable housing (not shown) preferably of the order of size of 21/2&#34;×3&#34;×1/2&#34; (63.5×76×12.7 mm) which includes a custom one-chip MCU 1 (Microcontroller Unit-HD614080  from Hitachi, Japan) loaded with a specially written computer program to implement each of the above described functions, a character generator custom masked RoM 3 (Read Only Memory, HN62321BP from Hitachi, Japan) a graphic liquid crystal display module capable of showing 16×128 dots graphic or to display one frame of a certain number of characters for a particular language (e.g., for the Chinese language, 8 characters can be shown in 16×16 dots font) which comprises of 2 drivers IC 4 and 5 (LCD segments driver HD61102 and LCD common driver HD61103 from Hitachi, Japan) and a high contrast LCD display 6 custom made by Seiko with which the whole LCD module is powered by a specially designed LCD power supply circuit 7, a lithium-battery-backed message storage read/write RAM 2 (HN6264FLP-3 from Hitachi, Japan) of capacity 8K×8 bits for storing message data, one or more pager identification codes and some programmable Oriental language characters; in particular, the Chinese character fonts and phrases. A key panel 10 comprises one 3 position sliding mode switch to activate the pager and 5 push-buttons for users operations. A radio frequency (RF) receiver module 8 comprises RF tune circuit, amplifier, filters and wave shaping circuits as a hybrid unit for capturing data signal from the air, a beeper and a light-emitting diode (LED) to generate the audio and visual alert signal upon message received, one piece of 1.5 volt AA-size battery 11 to power the RF receiver module 8, a DC-DC converter 9 to step up the voltage from battery 11 to power the remaining system and finally a small light bulb 12 or some other lighting device to provide background lighting to LCD module. 
     The pager is constructed (refer to FIG. 2) and programmed so that it can receive specially coded message and display characters of the Oriental languages, in particular, the Chinese language under user&#39;s control. The following paragraph describes the operation principle of the pager. 
     The paging company transforms the message in the Oriental language, in particular, the Chinese language or graphic information context using the paging computer system into a binary bit stream based on the floating storage technique coding algorithm, and then associates the message with either a specific pager receiver subscriber or the group broadcasting subscribers plus some redundant bits for self error correction and finally encodes all data bits as a complete message packet according to the Universal POCSAG standard (CCIR radio paging code No. 1) and broadcasts to the air through a particular radio frequency channel. 
     Assuming the pager has been switched active, the MCU 1 wakes up the RF receiver module 8 from time to time to detect if there is any message which requires its attention by comparing the identification code associated with the message with its own identification stored in the RAM 2 according to the dynamic identification concept. If the result is positive, MCU 1 stores the message into the RAM 2 for later repeated examination, and at the same time, searches the character generator ROM 3 and other programmable characters font or phrases table in RAM 2 to transform the message into the Oriental language or Chinese character or other graphic information and then shows the message on the LCD module. In addition, an alert tone is generated by the beeper unit and the LED is flashed inside the RF module 8 which is controlled again by the MCU 1. The user can switch off the tone by hitting any button on the key panel 10; otherwise, the tone will be turned off automatically after about 8 seconds by the MCU 1. 
     Battery 11, DC/DC converter 9 and LCD power circuit 7 serve to distribute the power to individual working modules of the paper. If the environment is dark and the LCD cannot be seen clearly, the user can press and hold the &#34;LIGHT&#34; button on the key panel 11 to turn on the light bulb or to the lighting devices 12 to have display illumination. 
     The beep tones can be substituted by a vibration alert unit if the user does not wish the tone to disturb other people. 
     The pager may provide both manual and auto time shut-off features to conserve power consumption. Battery low alert/indication is also provided. 
     The program of the MCU 1 can interpret information which has been encoded into a bit stream according to the Oriental language; in particular the Chinese character, coding system specially designed for the present invention based on the set forth floating storage technique and transmitted in standard POCSAG format in 512 baud speed or a higher baud speed switchable by the paging company. It can also support standard POCSAG alphanumeric display. 
     During data reception, the paper may provide 2 bits self error correction and 3 bits error detection capability for identification code matching while 1 bit self error correction and 2 bits error detection capability for message recovery to ensure maximum receiving reliability. 
     With RAM 2, the said pager can store up to 32 separate messages, the maximum length of each message depending on how the floating storage technique is being used, with no practical restriction. Standard alphanumeric messages transmitted in POCSAG format can also be recognised. The screen formats of the LCD module are different between the Oriental language; in particular the Chinese characters, and alphanumeric-characters display mode. In the former, each frame can display a number of Oriental language characters; in particular, 8 Chinese characters in 16×16 dot fonts; in the latter, each frame can display 2 lines×21 characters in 5×7 dot font. In addition, the pager can support both small and capital letter alphabets. The next paragraph will describe the detailed user operation of the paper. 
     The pager is suitably programmed so as to operate in one of the following 4 states: 
     a) Active state. 
     The MCU 1 receives and executes commands from the user via the key panel 10, allocating some spare time periodically to check if any message is coming from the RF receiver. Power is supplied to all components in this state. 
     b) Sleep state 
     System will go to sleep state from Active State when NO key on the keyboard has been pressed for approximately 30 seconds or the user has stepped through all the stored messages. In this state, the LCD module will be switched off. 
     c) Disable stage 
     The pager will enter this state if a DISABLE command has been received. This state is similar to the Sleep State except that further users&#39; commands will not be effective until an ENABLE command is received through broadcast. 
     d) Off State 
     User switches the pager to this state by sliding the mode switch to the OFF position. All components except the external RAM chip 2 will be cut off. The pager cannot receive any further message until turned back on. 
     In the following, NORMAL operation refers to operating the pager under Active or Sleep state. 
     The key panel 10 will be provided with the following keys, switches and buttons, the MCU 1 being suitably programmed to produce operation as described. 
     
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1   Mode switch: A 3 position slide switch with its                       
                 position to define the different users                   
                 operation modes:                                         
           ON:   The pager is under Active or                             
                 Sleep stage while an alert tone                          
                 will be heard and LED will be                            
                 flashed whenever a call has been                         
                 received.                                                
           M:    Same as ON made except the                               
                 alert tone will be disabled.                             
           OFF:  Pager is OFF. All memorised                              
                 messages will be erased.                                 
2   Next button: Enable user to examine individual                        
                 message in frame by frame basis if the                   
                 message is too long to be fitted within                  
                 one frame.                                               
3   READ button: Enable user to read next message in                      
                 FORWARD direction. Latest message                        
                 will be placed at the top position of the                
                 RAM buffer.                                              
4   BACK button: Enable user to read next message in                      
                 BACKWARD direction.                                      
5   DELETE button:                                                        
                 Enable user to delete the current                        
                 examined message from the RAM buffer.                    
                 To delete all messages, user can press                   
                 both the READ and BACK button.                           
6   Light button:                                                         
                 Display illumination will be effective                   
                 if this button has been pressed and held                 
                 down.                                                    
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     The provision of the above functions, both insofar as they are implemented by programming of the microprocessor and by the illustrated circuitry is a matter of routine for the skilled man.