Cordless telephone

Abstract: According to the invention, an E²P-ROM (46) which is a non-volatile memory element capable of electrically reading and writing data as a memory element to store ID codes is used and the remaining memory area (M2) of the non-volatile memory element is used to store abbreviated dialing numbers. This arrangement makes it unnecessary to separately provide a memory element to store the abbreviated dialing numbers and dispenses with the backup batteries for the abbreviated dialing numbers memory. Number of component parts can also be reduced to allow the telephone set to be manufactured at lower cost.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a cordless telephone which comprises a base unit and a remote unit which communicate with each other through radio transmission, where the base unit and the remote unit have the same identification code (abbreviated as ID code hereafter) which is transmitted when trying to call the remote unit from the base unit or trying to call the base unit from the remote unit whereupon communication between both units is established only when the received ID code agrees with its ID code. A cordless telephone set of this type is disclosed in EP-A-0115362. 2. Prior Art In a cordless telephone of the prior art, ID code is stored in an OTP-ROM (One Time programmable ROM), a fuse ?-ROM or the like. Abbreviated dialing numbers to call a destination telephone by identifying it with a number of digits less than the digits of the dialing number of the destination telephone are stored in a RAM installed in a processor circuit, which is realized by a microcomputer, or a RAM provided near the processor cirduit. consequently primary batteries or secondary batteries for the backup of the RAM which stores the abbreviated dialing numbers have usually been used in preparation for power outage. A cordless telephone which uses a RAM to store abbreviated dialling numbers is described in US-A-4761806. As explained, prior art requires the RAM to store ID codes and the RAM to store abbreviated dialing numbers to be separately provided, and batteries to backup the RAM which is a memory element to store the abbreviated dialing numbers to be provided. Thus the telephone set has been complex in the construction and high in the production cost. SUMMARY OF THE INVENTION The present invention has been made in view of the current situation as described above, for the purpose of providing a cordless telephone of lower cost and improved service capability for the user. The invention provides a cordless telephone which comprises a base unit and a remote unit which have the features of appended claim 1. In a preferred embodiment, the memory means of the remote unit is an electrically erasable programmable read only memory. In another preferred embodiment, the input means has means and to enter abbreviated dialing numbers consisting of a number of digits less than the digits of the dialing number of the destination terminal, the remote unit has means to read the ID code stored in the memory means and send it to 2nd modulator-transmitter circuits, and then send the output of the abbreviated dialing number entry means to the 2nd modulator-transmitter circuits, the memory means of the base unit stores dialing numbers which correspond to the abbreviated dialing numbers, the base unit further has means which, in response to output from 1st receiver-modulator means, reads the dialing number stored in the memory means corresponding to the abbreviated dialing number received following the ID code when the demodulated ID code agrees with the ID code stored in the memory means, and sends the signal representing the dialing number to the 1st modulator-transmitter circuits. According to a further embodiment, an EEP-ROM which is a non-volatile memory element capable of electrically reading and writing data as a memory element to store ID codes is used and the remaining memory area of the non-volatile memory element is used to store abbreviated dialing numbers. This arrangement makes it unnecessary to separately provide a memory element to store the abbreviated dialing numbers and dispenses with the backup batteries for the abbreviated dialing numbers memory. Number of component parts can also be reduced, enabling to manufacture the telephone set at lower cost. BRIEF EXPLANATION OF THE DRAWINGS These and other objectives, features and advantages of the invention will become more apparent when the detailed explanation that follows is read in conjunction with the drawings. FIG.1 is an outline block diagram illustrative of the electric wiring in the remote unit which constitute the cordless telephone set of the invention. FIG.2 is an outline block diagram illustrative of the electric wiring in the base unit which constitutes the cordless telephone set of the invention. FIG.3 is an outline block diagram illustrative of the electric wiring connecting a main microcomputer and a memory section which constitute the cordless telephone set of the invention. FIG.4 is a flow chart explanatory of the operation of a processor circuit 8 of the remote unit T1. FIG.5 is a drawing illustrative of the format of a signal transmitted by the remote unit T1. FIG.6 is a flow chart illustrative of the operation of the processor circuit 19 of the base unit T2 to store ID codes, abbreviated dialing numbers and the dialing numbers corresponding thereto, and is also explanatory of the operation of receiving signals from the remote unit T1. FIG.7 is a flow chart explanatory of the operation of the processor circuit 19 to transmit a signal which is received from the telephone line 50, from the base unit T2 to the remote unit T1. DETAILED EXPLANATION OF PREFERRED EMBODIMENTS Preferred embodiments of the invention are explained in detail by referring to the drawings. FIG.1 is an outline block diagram of the remote unit which constitutes the cordless telephone set of an embodiment of the invention. In FIG.1, 1 is an antenna, 2 is a receiver circuit, 3 is a detector circuit, 4 is an amplifier circuit, 5 is a speaker which is a ear piece, 6 is a wave-shaping circuit, 7 is a key matrix input means, 8 is a processor circuit, which is realized by a main microcomputer, 9 is a memory section which is a storage means comprising an EEP-ROM (Electrically Erasable Programmable ROM) which consists of a non-volatile memory element, 10 is a transmitter circuit, 11 is a modulator circuit, 12 is an amplifier for microphone output and 13 is the microphone. Input signal received by the antenna 1 and the receiver circuit 2 is detected in the detector circuit 3 and is amplified in the amplifier circuit 4. Output signal from the amplifier circuit 4 is introduced into the speaker 5. Output from the detector circuit 3 is introduced into the processor circuit 8 via the wave-shaping circuit 6. The processor circuit 8 and the memory section 9 are connected by a bidirectional connection. The memory section 9 is arranged so that the ID code and abbreviated dialing numbers provided to call a destination telephone by identifying it with a number of digits less than the digits of the dialing number of the destination telephone, which are sent from the processor circuit 8, are stored in the respective memory areas. The processor circuit 8 reads the ID codes and the abbreviated dialing numbers which are stored in the memory section 9 as required. The processor circuit 8 is fed with output of the key input means 7, and the output is introduced into the antenna 1 via the modulator circuit 11 and the transmitter circuit 10. Output of the microphone 13 is amplified in the microphone amplifier 12 and is fed to the modulator circuit 11. FIG.2 is an outline block diagram illustrative of the base unit T2 which constitutes the cordless telephone set of an embodiment of the invention. In FIG. 2, 14 is an antenna, 15 is a receiver circuit, 16 is a detector circuit, 17 is a wave-shaping circuit, and 18 is a memory section which includes an EEP-ROM. 19 is a main microcomputer which has a memory area M1 to store ID codes and another memory area M2 to store the abbreviated dialing numbers. 20 is a modulator circuit, 21 is a transmitter circuit, 22 is a 2-wire/4-wire converter circuit, 23 is a diode bridge and 24 is a connector terminal for a telephone line 50. Input signal received by the antenna 14 and the received circuit 15 is detected in the detector circuit 16. Detector output is introduced into the 2-wire/ 4-wire converter circuit 22 and is, at the same time, introduced into the processor circuit 19 via the wave-shaping circuit 17. Output of the 2-wire/4-wire converter circuit 22 is transmitted onto the telephone line 50 via the diode bridge 23 and the connector terminal 24. Signals sent from a mating terminal on the telephone line 50 are introduced into the modulator circuit 20 via the connector terminal 24, the diode bridge 23 and the 2-wire/4-wire converter circuit 22, and then introduced into the antenna 14 via the transmitter circuit 21. FIG.3 is a block diagram illustrative of the specific construction of the processor circuit 19 and the memory section 18. The processor circuit 19 and the memory section 18 are connected by a bidirectional connection. The memory section 18 has a memory area M1 to store the ID code which is sent from the processor circuit 19 and another memory area M2 to store the abbreviated dialing numbers. The processor circuit 19 reads the ID code and the abbreviated dialing numbers stored in the memory section 18 as required. Output of the processor circuit 19 is used in the modulator circuit 20 to modulate the carrier wave which is then introduced into the antenna 14 via the transmitter circuit 21. FIG.4 is first referred to in the following explanation of the operation of the remote unit T1 in the cordless telephone, followed by the explanation of the signal sent by the remote unit T1 shown in FIG.4 via radio transmission. In the remote unit T1, upon proceeding from step r1 to step r2, the operation proceeds to step r3 when one or more ID codes are stored in the memory means in advance. A call key 7a of the key input means 7 is pressed and thereafter numeral keys 7e are operated to enter a dialing number. Or an abbreviation button 7b is pressed after pressing the call key 7a, and then the abbreviated dialing number is entered by operating the numeral keys 7e. Whereupon the processor circuit 8 reads the ID code which was stored in the memory means 9 in advance, and feeds the signal to the modulator circuit 11 in step r4 where carrier wave is modulated in step r5. In step r6, modulated carrier wave from the modulator circuit 11 is power-amplified in the transmitter circuit 10 and is transmitted from the antenna 1 in step r6. The dialing number which was entered through the numeral keys as mentioned before is modulated by the modulator circuit 11 and is transmitted by the transmitter circuit 10 via the antenna 1. When abbreviated dialing number has been entered instead of the dialing number, the modulator circuit 11 modulates the carrier wave with a signal which represents the abbreviated dialing number, and the carrier wave is transmitted by the transmitter circuit 10 via the antenna 1. Format of the radio signal which is transmitted from the remote unit T1 via the antenna 1 in step r6 is shown in FIG. 5 (1). The memory means 9 in the remote unit T1 may be a random access memory which is constantly energized by primary batteries or secondary batteries, or an EEP-ROM which is similar to the memory means 18. When a RAM is used for the memory means 9 in the remote unit T1, even when the stored data of the RAM is erased due to exhaustion of the batteries, the same ID codes can be easily stored again in the storage area M1 of the memory means 18 in the base unit T2, by entering the ID codes again by the operation of the input means 7. With the ID code which represents the combination of the remote unit T1 and the base unit T2 stored in the memory means 9 and 18, interference in communication can be prevented when plurality of combinations exist by setting different ID codes for the respective combinations, and it is enabled to make telephone communication over a desired trunk line. It is not necessary to store the abbreviated dialing numbers and the corresponding dialing numbers in the memory means 9. Therefore, in case the memory means 9 is realized by means of a random access memory, erasure of the content thereof does not cause a trouble but requires only to enter the ID code again as mentioned before. Operation of the base unit T2 is explained briefly. In the base unit T2, the signal from the remote unit T1 is received by the receiver circuit 15 via the antenna 14, and is demodulated in the detector circuit 16. Then the waveform of the signal is corrected by the wave-shaping circuit 17 and the signal is fed to the processor circuit 19 in the form of serial data. The processor circuit 19 reads the ID code which was stored in the memory section 18 beforehand and compares it with the ID code which has been received from the remote unit. When both ID codes are identical, radio transmission from the base unit T2 is enabled to establish the radio transmission circuit between the remote unit T1 and the base unit T2, thereby enabling the radio communication between the remote unit T1 and the base unit T2. After telephone communication with the mating terminal has been enabled via the base unit T2 and the telephone line 50, audio signal from the microphone 13 of the remote unit T1 is amplified by the microphone amplifier 12, modulated by the modulator circuit 11 and is transmitted to the base unit T2 by the transmitter 10 via the antenna 1. In the base unit T2, the audio signal is received by the receiver circuit 15 via the antenna 14 and is sent out onto the telephone line 50 via the 2-wire/4-wire converter circuit 22, the diode bridge 23 and the connector terminal 24. Audio signal which is sent over the telephone line 50 from the mating terminal is fed to the modulator circuit 20 via the connector circuit 24, diode bridge 23 and the 2-wire/4-wire converter circuit 22. In the modulator circuit 20, and the modulated carrier wave is transmitted to the remote unit T1 by the transmitter circuit 21 via the antenna 14. Radio signal transmitted from the antenna 14 has a format similar to that shown in FIG.5 (2). In the remote unit T1, the incoming signal is received by the receiver circuit 2 via the antenna 1 and is demodulated in the detector circuit 3. The audio signal which is demodulated in the detector circuit 3 is amplified in the amplifier circuit 4 to a level enough to drive the speaker 5, and is delivered as acoustic signal from the speaker 5. Registration of the ID code and the abbreviated dialing numbers is performed by operating the key input means 7. When no ID code is stored in the memory means 9 and 18, the sequence in the remote unit T1 moves from step r2 to step r8 where the memory key 7c provided on the input means 7 is pressed, ID code entry key 7d is operated and the numeral keys 7e are operated thereby to enter the ID code. The ID code is stored in the memory means 9 by the work of the processor 8. The ID code is also sent from the processor circuit 8 to the modulator circuit 11 where it modulates the carrier wave which is transmitted by the transmitter 10 via the antenna 1 to the base unit T2. In order to enter an abbreviated dialing number through the key input means 7 and store it in the storage area M2 of a memory means 46, the memory key 7c is operated followed by the operation of the abbreviation button 7b, then the numeral keys 7e are operated to enter the abbreviated dialing number followed by the entry of the dialing number by means of the numeral keys 7e. The abbreviated dialing number and the corresponding dialing number which are entered in this way are transmitted to the base unit T2 via the modulator circuit 11, the transmitter circuit 10 and the antenna 1. In order to store the ID code in the memory means 9 and 18, and to store the abbreviated dialing number and the corresponding dialing number in the memory means 18, the signal representing the ID code is transmitted from the remote unit T1 and thereby communication in combination of the remote unit T1 and the base unit T2 is performed, as described before. The following description explains the operations of writing and reading the ID code and the abbreviated dialing number by means of the processor circuit 19 and the memory section 18 of the base unit T2, with reference to FIGs. 2, 3, 6 and 7. In FIG. 3, 31 is an input/output port to receive data via a wave-shaping circuit 17 and to send data to a modulator circuit 20, 32 is an input/output port to exchange various data with the memory section 18, 34 is a ROM, 35 is a bus controller section, 36 is a RAM and 37 is a data bus to send data to these internal circuits. 41 is a command register, 42 is a controller circuit, 43 is a data register, 44 is a read/write circuit, 45 is a decoder circuit and 46 is an EEP-ROM circuit (abbreviated as E²P-ROM hereafter). In step s1 in FIG. 6, the ID code or the abbreviated dialing number and the corresponding dialing number transmitted from the remote unit is received, demodulated in the detector circuit 16 in step s2, processed to trim the waveform in the wave-shaping circuit 17 in step s1, and is fed to the processor circuit 19 via the line 43. In FIG.3, the signal which represents the ID code and has been received via the input/output port 31 is tentatively stored in a RAM 36 via a data bus 37 in step s4. In case the ID code is not stored in the storage area M1 of the E²P-ROM in the memory means 48, as will be described later, when one ID code consisting of a string of numerical characters is stored in the RAM 36, then writing of it in the E²P-ROM 46 of the memory section 18 via the input/output port 32 is started. This means that it is determined in step s5 whether a write command is sent to the command register 41 of the memory section 18 from the input/output port 32. This command code is tentatively held by the command register 41 before being sent to the controller circuit 42. In step s6, the controller circuit 42 moves into the mode of writing in storage area M1 of the E²P-ROM 46 by decoding the entered command code. Then in step s7, data signal representing the ID code which has been sent from the RAM 36 via the input/output port 32 is stored by the read/write circuit 44 in the specified storage area M1 of the E²P-ROM 46 via the data register 43. Location in the storage area M1, where the data signal is to be stored, is determined by means of an address signal, which has been transferred via the input/output port and an address bus, and is decoded by the decoder circuit 45. On the other hand, the ID code which was stored in the E²P-ROM 46 in the procedure described above is read by skipping from step s5 to s8 and sending a read command from the input/output port 32 of the processor circuit 19 to the command register 41 of the memory section 18. Namely, operation is turned to read mode by sending the command code which has been tentatively stored in the command register 41 to the controller circuit 41 and decoding the command code in the controller circuit 42. Then the ID code is read from the specified storage area M1 of the E²P-ROM 46 by the read/write circuit 44 in step s9, and in step 10 the ID code is sent to the input/output port 32 of the processor circuit 19 after being tentatively stored in the data register 43. In step 11, the processor circuit 19 compares the ID code from the remote unit T1 which has been sent from the input/output port 31 with the ID code which has been read from the E²-ROM 46 and, if these ID codes are identical, turns on the radio transmission of the base unit T2 in step s12 and establishes the radio communication circuit with the remote unit T1 in step s13. In FIG. 7, to send the signal from the base unit T2 to the remote unit T1 via the antenna 14, the operation moves from step u1 to step u2 as shown in FIG.7 and the signal from the telephone line 50 is received in the processor circuit 19. When it is determined that a read command is sent in step u3 from the input/output port 32 to the command register 41 shown in FIG.3, the operation moves to step u4 where the ID code is read by the read/write circuit 44 and then moves to step u5 where the ID code is sent from the data register 43 to the decoder circuit 20 where the carrier wave is modulated and is transmitted through the antenna 14 after being power-amplified in the transmitter circuit 21. After the ID code is transmitted in step u6, the signal from the telephone line 50 is processed to modulate the carrier wave which is transmitted by the transmitter circuit 21 via the antenna 14. Registration of abbreviated dialing numbers in the remaining storage area M2 of the E²-ROM 46 where the ID code has been stored in the above procedure, can be performed similarly to the above registration procedure of the ID code, and is not explained here. While E²P-ROM 46 is installed in the base unit T2 in the embodiment described above, it may be installed in the remote unit T1 in another embodiment of the invention.

Claims: A cordless telephone which comprises a base unit and a remote unit which are capable of communicating with each other through radio transmission, where both the base unit (T2) and the remote unit (T1) have the same ID code stored in respective memory means (18; 9), said memory means including a non-volatile memory element which is capable of electrically reading and writing data for storing the ID code, whereby abbreviated dialling numbers are storeable in the remaining memory area of the non-volatile memory element, the base unit (T2) and the remote unit (T1) being arranged such that said ID code is transmitted when calling the remote unit (T1) from the base unit (T2) or calling the base unit (T2) from the remote unit (T1), whereupon communication between both units (T1, T2) is established only when the ID code of the remote unit (T1) is identical to the ID code of the base unit (T2), whereby the remote unit further includes input means (7) for inputting said ID code and abbreviated dialling numbers into said memory means (9) upon activating programming keys (7b, 7c, 7d) and numerical keys (7e) corresponding to the ID code or the abbreviated dialling numbers, respectively, and means for subsequently outputting a radio transmission to the base unit (T2), and the base unit further includes detecting means (16) for receiving said output radio transmission and for detecting activation of said programming keys and control means (19) for outputting a write signal in response to said detecting means detecting activation of said programming keys, said memory means (18) being operatively connected to said control means (19) and capable of accessing and storing said ID code and said abbreviated dialling numbers upon receiving of said write signal, respectively. The cordless telephone as claimed In claim 1, wherein the memory means (9) of the remote unit (T1) is an electrically erasable programmable read only memory. The cordless telephone as claimed in claim 1, wherein the remote unit (T1) has means (8) to read the ID code stored in the memory means (9) and send it to 2nd modulator-transmitter circuits (10, 11), and then send the output of the abbreviated dialing number entry means (7b, 7e) to the 2nd modulator-transmitter circuits (10, 11), the memory means (18) of the base unit (T2) stores dialing numbers which correspond to the abbreviated dialing numbers, the base unit (T2) further has means (19) which, in response to output from 1st receiver-modulacor means (15, 16), reads the dialing number stored in the memory means (18) corresponding to the abbreviated dialing number received following the ID code when the demodulated ID code agrees with the ID code stored in the memory means (18), and sends the signal representing the dialing number to the lst modulator-transmitter circuits (20, 21).

Inventors: YAMASHITA KOUJI, YAMASHITA, KOUJI
Applicants: SHARP KK, SHARP KABUSHIKI KAISHA
Application year: 1989
Main classification: H04M1
IPC codes: H04Q7, H04M1