Portable telephone unit

Abstract: A buffer memory, an electrically erasable and writable ROM, a capacitor for holding voltage, and a voltage detection circuit for detecting the voltage of a battery for power source are provided in a portable telephone unit. During conversation, data to be conserved are written into the buffer memory. At time of clearing conversation, the data written in the buffer memory are transferred to a ROM and written therein. When the voltage detection circuit detects a fact that the voltage of the battery is unobtainable, the buffer memory and the ROM are operated and the data written in the buffer memory are also transferred to the ROM and written therein by the voltage held in the capacitor.

Description: The present invention relates to a portable telephone unit and more particularly to a portable telephone unit being capable of preserving data updated during conversation. In a portable telephone unit, there are several tens of bytes of data that are renewed every second such as billing information and conversation time, but there are some types in which such data are held in an internal memory. Further, as such a memory, an electrically erasable and writable read-only memory (ROM), which is so called an electrically erasable programmable read-only memory (EEPROM), is used in general. Now, a portable telephone unit is made so that a charging type battery for power source can be removed comparatively easily for the purpose of exchange or the like. Further, the battery can be displaced sometimes by a shock and so on. Where a memory with a parallel interface is used as an EEPROM for holding said data, when a battery is removed, such a fact is detected by a voltage detection circuit and said data are written in the EEPROM immediately. Further, the power source for the period when the write is executed is provided by a charge from a capacitor. In a portable telephone unit, however, LSI chips are used widely for the purpose of miniaturization of the apparatus and so on. Therefore, the current consumption during the period when data are written in the EEPROM is increased, resulting in the capacity of a capacitor for supplying power during the write period needing to be made larger, which prevents miniaturization of the telephone. Further, when a memory with a series interface is used as the EEPROM, the time required for write of data is protracted. Therefore, it is still impossible to cover the time required for writing the data with a charge from a capacitor. Thus, the data are written in the EEPROM every second at normal time, too. However, the writable number of times of an EEPROM is approximately hundred thousand times in general and, even when the use time of a portable telephone unit is two minutes a day, the number of write operations reaches 87,600 in two years (= 60 seconds x 2 minutes x 365 days x 2 years). So, it is required to exchange the EEPROM in approximately two years, thus shortening the life of a product. Furthermore, there is also a method in which a RAM is backed up with a primary battery so as to make it nonvolatile, but, in order to back up the RAM for several years with a primary battery only, the capacity of the primary battery has to be made larger. The present invention has been made for the purpose of solving such problems as described above. EP 0,545,066 A discloses a mains electricity-supplied telephone answering device which transfers data from a rewritable memory to a writable non-volatile memory when a power failure is detected. EP 0,404,061 A discloses a battery powered computer which transfers data from a volatile memory to a non-volatile memory when the output voltage of the battery becomes lower than a predetermined value. According to the present invention, even when a built-in battery is removed and so on and the voltage of the built-in battery is interrupted, the data to be conserved will never be lost. Further, even when the number of writable times of the EEPROM is small, the life of products will never be shortened. Furthermore, it is possible to miniaturize a capacitor for power source, and, as a result, miniaturization of a telephone set will never be prevented. Further, a primary battery for making the memory non-volatile is neither required, and miniaturization becomes possible from this point, too. According to the present invention, there is provided a portable telephone unit capable of preserving data that are renewed during conversation, comprising: a battery for a power supply; a voltage holding circuit for holding the output voltage of said battery; a voltage detecting circuit for detecting the output voltage of said battery; and a controller; characterized by: a data preserving circuit having a buffer memory, an erasable and writable read only memory and a write/read logic circuit and supplied with the output voltage of said battery through said voltage holding circuit; wherein: said controller is arranged to write, during conversation, said data that are renewed in said buffer memory, and said write/read logic circuit is arranged to read out the data, when conversation is terminated, that have been written in said buffer memory and write these data in said read only memory based on an instruction from said controller; and said write/read logic circuit is arranged to read out the data that have been written in said buffer memory, when said voltage detecting circuit outputs a detection signal representing that the output voltage of said battery is outside acceptable tolerances, and write these data in said read only memory in response to said detected signal. The invention will be further described by way of non-limitative example, with reference to the accompanying drawings, in which:- Fig. 1 is a connection diagram showing an example of the present invention. The invention may be embodied in other specific forms without departing from the characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. In Fig. 1, a reference numeral 1 represents a transmitter-receiver circuit, and an aural signal from a telephone transmitter 2 is converted into a transmission signal of an up-channel by the transmitter-receiver circuit 1 and transmitted from a transmitting/receiving antenna 4 to a base station at time of conversation. Further, a signal of a down-channel from the base station is received by the antenna 4, this received signal is supplied to the transmitter-receiver circuit 1 and the aural signal of the other party is taken out, and this aural signal is supplied to a telephone receiver 3. Furthermore, various commands and data accessed between the portable telephone unit and the base station are also transmitted and/or received by the transmitter-receiver circuit 1. Further, a reference numeral 10 denotes a microcomputer for system control for performing processing of commands and data and so on. Further, in this microcomputer 10, 11 represents a CPU functioning as a principal processing controller, 12 represents a ROM in which various programs have been written, and 13 represents a RAM for a work area. Further, these memories 12 and 13 are connected to the CPU 11 through a parallel system bus 19. Further, signal lines of commands and data transmitted and/or received by the transmitter-receiver circuit 1 are also connected to the system bus 19. Furthermore, a conservation circuit 20 for conserving various data required to be conserved such as billing information and conversation hour is provided. Namely, a buffer memory 21 is connected to the bus 19, and an EEPROM 23 is also connected to this buffer memory 21 through a write/read logic circuit 22. In this case, the buffer memory 21 is for inputting and outputting data such as billing information in parallel and also for holding the data temporarily, and is formed to have a size of several tens of bytes corresponding to the data quantity. Further, the logic circuit 22 reads data out of the buffer memory 21 in parallel, converts these data into series data and writes them in the EEPROM 23, and also reads the data in series from the EEPROM 23, and converts these data into parallel data and writes them in the buffer memory 21. Furthermore, the EEPROM 23 has the capacity of several tens of bytes corresponding to the data quantity of data to be conserved. Further, a command interpretation logic circuit 24 is connected to the bus 19, and an output signal S24 thereof is supplied to the logic circuit 22. Furthermore, a charging type battery (a secondary battery) 31 is included inside, the output voltage thereof is supplied to a constant-voltage circuit 32 and stabilized. Further, the output voltage V32 of the constant-voltage circuit 32 is supplied to power lines of the circuits 21 to 23 through a diode 33 for reverse current prevention. A capacitor 34 for holding voltage is also connected between the output side of the diode 33 and the ground. The stabilized voltage V32 is supplied also to respective parts except circuits 21 to 23 as the working voltage thereof. Furthermore, a voltage detection circuit 35 is connected to the battery 31 so as to detect whether the voltage of the battery 31 is obtainable or not, and the detected output S35 is supplied to the logic circuit 22. In such a structure, since the output voltage V32 of the constant-voltage circuit 32 is supplied to respective parts and is also supplied to the circuits 21 to 23 through the diode 33 at stationary time, respective parts can perform original operations so as to make a call or the like. Further, at time of conversation, the data to be conserved such as billing information and conversation hour are written every second in the buffer memory 21 by means of the CPU 11 and renewed succeedingly. Further, when conversation is completed and clear-back processing is executed, a predetermined command is written in the logic circuit 24 by means of the CPU 11. Then, this command is interpreted by the logic circuit 24, and the logic circuit 22 is started by an output signal S24 of the logic circuit 24. As a result, the data of the buffer memory 21 are read out by the logic circuit 22 and are converted into series data from parallel data, and these series data are written in the EEPROM 23 by means of the logic circuit 22. Thus, the values (data) at clear-back time of data to be conserved in the buffer memory 21 are conserved in the EEPROM 23. On the other hand, when the appropriate output voltage from the battery 31 becomes unobtainable due to a certain cause or the fact that the battery 31 is removed during conversation, such a fact is detected by a detection circuit 35 and a detected signal S35 is supplied to the logic circuit 22. Then, the logic circuit 22 is started by a detected signal thereof, and, similarly to the case by the signal S24, the data of the buffer memory 21 are read out by the logic circuit 22 and converted into series data from parallel data. These series data are written in the EEPROM 23 by means of the logic circuit 22. Thus, present values (data) of the data to be conserved in the buffer memory 21 are conserved in the EEPROM 23. Further, in this case, although the voltage of the battery 31 is unobtainable during the period when the data of the buffer memory 21 are transferred to the EEPROM 23, transfer of these data is executed normally because the charging voltage of the capacitor 34 is supplied to the circuits 21 to 23 as the working voltage thereof. Besides, when a predetermined command is written in the logic circuit 24 from the CPU 11, it is interpreted by the logic circuit 24, the logic circuit 22 is started by the output signal S24 of the logic circuit 24, the data of the EEPROM 23 are read out by the logic circuit 22 and also converted into parallel data from series data, and these parallel data are written in the buffer memory 21 by means of the logic circuit 22. Accordingly, it is possible thereafter for the CPU 11 to learn billing information, conversation hour and so on up to that time by referring to the data of the buffer memory 21. As described above, renewed values are always conserved for the data to be conserved such as billing information and conversation hour. In this case, however, according to this portable telephone unit, even when the data are renewed every second at time of conversation, renewal of these data is made by means of the buffer memory 21, and the data resulting from renewal are written in the EEPROM 23 at time of clearing. Therefore, even when the number of writable times of the EEPROM 23 is approximately hundred thousand times, the life of products will never be shortened. Further, even when the battery 31 is removed and so on and the voltage of the battery 31 is interrupted, the data of the buffer memory 21 at that time are written in the EEPROM 23. Therefore, the data to be conserved will never be left out. Furthermore, since only the circuits 21 to 23 are operated when the data of the buffer memory 21 are transferred to the EEPROM 23 in case the voltage of the battery 31 is interrupted, it is not required to make the capacitor 34 for providing the working voltage of the circuits 21 to 23 to have a large capacity, thus making it possible to miniaturize the capacitor 34. As a result, miniaturization of the telephone set is not prevented. Further, a primary battery for making the memory nonvolatile is neither required, and miniaturization can also be expected from this point.

Claims: A portable telephone unit capable of preserving data that are renewed during conversation, comprising: a battery (31) for a power supply; a voltage holding circuit (34) for holding the output voltage of said battery; a voltage detecting circuit (35) for detecting the output voltage of said battery; and a controller (11); characterized by : a data preserving circuit (21-23) having a buffer memory (21), an erasable and writable read only memory (23) and a write/read logic circuit (22) and supplied with the output voltage of said battery (31) through said voltage holding circuit; wherein: said controller (11) is arranged to write, during conversation, said data that. are renewed in said buffer memory (21), and said write/read logic circuit (22) is arranged to read out the data, when conversation is terminated, that have been written in said buffer memory and write these data in said read only memory (23) based on an instruction from said controller; and said write/read logic circuit (22) is arranged to read out the data that have been written in said buffer memory, when said voltage detecting circuit (35) outputs a detection signal representing that the output voltage of said battery is outside acceptable tolerances, and write these data in said read only memory in response to said. detected signal. A portable telephone unit according to claim 1, wherein the output voltage of said battery (31) is supplied to the portions of said portable telephone unit other than said data preserving circuit (21-23) without through said voltage holding circuit.

Inventors: SOMEYA TAKAHISA, TERASHIMA KAZUHIKO, SOMEYA, TAKAHISA, TERASHIMA, KAZUHIKO, Someya, Takahisa, c/o Sony Corp., Terashima, Kazuhiko, c/o Sony Corp.
Applicants: SONY CORP, SONY CORPORATION
Application year: 1996
Main classification: H04M1
IPC codes: H04M1, H04Q7