JP3335439B2 - Terminal for data communication - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal device for data communication using a telephone line, and to a data communication terminal device for transmitting and receiving data using a dual tone multi-frequency signal.

[0002]

2. Description of the Related Art Conventionally, a multi-frequency (dual tone multi-frequency; hereinafter referred to as DTMF) signal transmitting apparatus utilizing a telephone line and a detection analyzing apparatus for detecting and analyzing a received DTMF signal are provided. ,
2. Description of the Related Art There is a data communication terminal device for bidirectional communication for transmitting and receiving data by a DTMF signal. In such a communication terminal device, at the time of transmitting a DTMF signal, only the transmitting device functions and the detection and analysis device is in a pause state,
Conversely, when the DTMF signal is supplied and the DTMF signal is detected and analyzed, only the detection and analysis device functions and the transmission device is in a pause state. However, the DTMF signal transmitting device and the D
In a conventional data communication terminal device equipped with a TMF signal detection / analysis device, power is supplied to both the transmission device and the detection / analysis device regardless of transmission / reception, resulting in a large power consumption. There is. In particular, in a data communication terminal device in which the transmission device and the detection analysis device use a battery provided in the data communication terminal device as a driving power source, the large power consumption indicates that the data communication terminal device has a large power consumption. This is a serious problem because it greatly affects the operable time of the device. Conventionally, since the impedance at the output unit of the transmission device and the detection analysis device matches the line impedance of the telephone line, the amplified DT is used during transmission.
There is also a problem that the level loss before the MF signal is transmitted to the telephone line is large, and the loss of the signal level supplied to the detection analyzer at the time of signal reception is large. The present invention has been made to solve such a problem, and an object of the present invention is to provide a data communication terminal device that consumes less power and has less loss of signal level.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a line transformer having a primary side connected to a telephone line, and a DTMF signal supplied from the telephone line having an input side connected to a secondary side of the line transformer. DTMF for detecting and analyzing
DTMF generating and transmitting means for generating and transmitting a DTMF signal indicating the data content, the output side being connected to the secondary side of the line transformer, and DTMF indicating the data content transmitted by the DTMF generating and transmitting means. A data communication terminal device for transmitting a signal using the telephone line via the line transformer, wherein an output side of the DTMF detection / analysis means and an input side of the DTMF creation / transmission means are connected and transmitted. A transmission permission state is set based on the supply of data, and a reception permission state is set based on a data transmission end signal included in the data. On the other hand, during data communication, the data supplied from the DTMF detection / analysis means is set. A transmission permission state is set based on the supply of the transmission end signal, and transmission is performed in accordance with each of the transmission permission state or the reception permission state. A control unit for transmitting a permission signal or a reception permission signal; an input side connected to the power supply unit; and an output side connected to the DTMF detection analysis unit and the DTMF creation and transmission unit, and the transmission permission signal supplied from the control unit. Sometimes, power is supplied to the DTMF creation / transmission means, and power is not supplied to the DTMF detection / analysis means. When the reception permission signal is supplied from the control means, power is supplied to the DTMF detection / analysis means and
And a power supply selection unit that does not supply power to the TMF creation and transmission unit.

[0004] With this configuration, the power supply selection means supplies power to only one of the DTMF creation / transmission means and the DTMF detection / analysis means based on the transmission permission signal and the reception permission signal supplied from the control means. Therefore, it works to reduce the power consumption.

Further, according to the present invention, the DTMF creation / transmission means includes a DTMF which has an input side connected to the control means and indicates data contents based on data supplied from the control means.
A DTMF dialer for generating a signal, and the DTMF dialer which is connected in series between an output side of the DTMF dialer and a secondary side of the line transformer and is transmitted by the DTMF dialer
An amplifier for amplifying the F signal may be provided, and the secondary line of the line transformer and the D
A first resistor connected in series between a connection point between the input side line of the TMF detection / analysis means and the output side of the amplifier;
The second connected in series to the input side line of the TMF detection and analysis means
A resistor, and the primary side and the second side of the line transformer.
The impedance on the secondary side may be 600 ohms, the resistance of the first resistor may be less than 600 ohms, and the resistance of the second resistor may be more than 600 ohms.

With such a configuration, the power supply selecting means does not supply power to the amplifier at the time of reception, so that the output side of the amplifier is set to a high impedance state at the time of reception. Further, setting the resistance value of the second resistor to be larger than the impedance of the secondary side of the line transformer acts to bring the secondary side of the line transformer into a high impedance state during reception. Thus, the power supply selection means and the second resistor act so that the supplied DTMF signal is transmitted to the DTMF detection and analysis means with a small transmission loss. Further, the power supply selecting means does not supply power to the DTMF detection / analysis means at the time of transmission, and thus acts to set the input side of the DTMF detection / analysis means to a high impedance state at the time of transmission. Further, the fact that the resistance value of the second resistor is larger than the impedance of the secondary side of the line transformer acts so that the input side of the DTMF detection / analysis means is brought into a high impedance state during transmission. Further, making the resistance value of the first resistor smaller than the impedance on the secondary side of the line transformer acts to reduce the transmission loss of the DTMF signal from the amplifier to the line transformer. Thus, the power supply selection means, the first resistor and the second resistor act so that the amplified DTMF signal is transmitted to the telephone line with little loss.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a data communication terminal according to the present invention will be described below with reference to FIG. Note that the data communication terminal device 1 of the present embodiment is for bidirectional communication for transmitting and receiving data by a DTMF signal. Terminals L1 and L2 in data communication terminal device 1 in the present embodiment
Is connected to a telephone line, and terminals T1 and T2 are connected to home telephones. The terminals L1 and L2 and the terminals T1 and T2 are connected to the divider 50, respectively, and the terminals L1 and L2 are connected to the terminals 2 and 3 of the relay 52 via the divider 50 and the filter 51. The separator 50 is switched between the “TEL” side and the “AUTO” side, and is normally switched to the “AUTO” side. If an accident occurs in the data communication terminal device 1, “ By switching to the "TEL" side, the telephone line is forcibly connected to the home telephone. The terminals of the separator 50 connected to the home telephone when the separator 50 is switched to the “AUTO” side are:
It is connected to terminals 5 and 7 of relay 52 via a call detection circuit 8 for detecting the use state of the home telephone. Also, relay 5
The terminals 4 and 6 are connected to a line control circuit 9 described later. The relay 52 connects either the terminal 4 or the terminal 5 to the terminal 2 and the terminal 6 or the terminal 7 to the terminal 3, that is, connects the telephone line to the data communication terminal 1. Alternatively, it is connected to either the home telephone. Normally, terminal 2 of relay 52
Is connected to the terminal 5, the terminal 3 is connected to the terminal 7, and the relay 52 connects the telephone line to the filter 51, the call detection circuit 8 and the disconnector 5.
0 when the home telephone is not in use by the call detecting circuit 8 when data communication is performed, the microcomputer 5 is connected to the home telephone.
The terminal 2 of the relay 52 is connected to the terminal 4 and the terminal 3 of the relay 52 is connected to the terminal 6 by the control signal transmitted by the relay 3. The relay 52 connects the telephone line to the terminal device 1 for data communication via the filter 51.

The line control circuit 9 has a function of generating a rotary dial pulse (hereinafter, referred to as DP) transmission signal, an off-hook function, and an on-hook function. Is set. Such a line control circuit 9 includes a line transformer 5
4 and the input side of the full-wave bridge circuit 10. The output side of the full-wave bridge circuit 10 is connected to a power supply selection switch 12 via a DC / DC converter 11 that generates a 5V voltage.

On the other hand, a secondary side of the line transformer 54 is connected to an input side of the DTMF detection analyzer 17 via a second resistor 56. Further, the output side of the DTMF detection analyzer 17 is connected to the microcomputer 5 via a level converter 18.
3 is connected. The DTMF detection analyzer 17 is a DTMF
When the signal is supplied, a data transmission end signal which is a part of the DTMF signal is detected and analyzed, and the data transmission end signal is sent to the microcomputer 53 via the level converter 18. The second resistor 56 is connected to the secondary line of the line transformer 54 by the DTMF detection analyzer 1.
7 is connected in series to the input side line.

The data output terminal of the microcomputer 53 is connected to the DTMF dialer 13 via the level converter 14. The DTMF dialer 13 is a level converter 1
4, the contents of the data supplied from the microcomputer 53 are created and transmitted as DTMF signals.
On the output side of the DTMF dialer 13, a low-pass filter 15, an amplifier 16 and a first resistor 55 are connected in series.
The first resistor 55 is connected to a connection point between the secondary line of the line transformer 54 and the input line of the DTMF detection analyzer 17,
It is connected between the output terminal of the amplifier 16.

The data communication terminal device 1 is driven by power from a built-in lithium battery. The operating voltage of the microcomputer 53 is 3.6 V of the lithium battery voltage. Analyzer 17
The level converter 18 connected to the output side of the microcomputer 53 operates to convert the voltage of the signal from 5 V to 3.6 V, and the level converter 14 connected to the output side of the microcomputer 53.
Performs an operation of converting the data voltage from 3.6V to 5V.

The impedance on the primary side and the secondary side of the line transformer 54 are both 600 ohms, the resistance value of the first resistor 55 is 220 ohms, and the resistance value of the second resistor is 22 K ohms.

On the other hand, the output side of the power supply selection switch 12 is connected to a DTMF dialer 13, a low-pass filter 15, an amplifier 16 and a DTMF detection analyzer 17, respectively, and the power supply selection switch 12 is supplied from a microcomputer 53. The power supply destination is selected by the control signal. That is, when transmitting the DTMF signal, the transmission permission signal transmitted from the microcomputer 53 is supplied to the power supply selection switch 12, so that the power supply selection switch 12 supplies power to the DTMF dialer 13, the low-pass filter 15, and the amplifier 16. The DTMF detection analyzer 17 is not supplied with power. On the other hand, when a DTMF signal is received, the reception permission signal sent from the microcomputer 53 is supplied to the power supply selection switch 12, so that the power supply selection switch 12 supplies power only to the DTMF detection analyzer 17, Power is not supplied to the DTMF dialer 13, the low-pass filter 15, and the amplifier 16.

The microcomputer 53 switches between the transmission permission signal and the reception permission signal as follows. As will be described later, sensors and the like are connected to the microcomputer 53 via an interface. When data is supplied from the sensor to the microcomputer 53, the microcomputer 53 detects the supply of the data, sets a transmission permission state, and transmits a transmission permission signal.
Further, by recognizing the completion of transmission of the data transmission end signal provided in the data, the reception permission state is set and the reception permission signal is transmitted. After the data communication is started in this way, a transmission permission signal is transmitted based on a data transmission end signal provided in the DTMF signal supplied from the host. That is, since a transmission end signal indicating the end of the transmission of the data is added to the data transmitted by the DTMF signal as is well known, the DTMF detection analyzer 17 to which the DTMF signal is supplied transmits the transmission end signal. Perform detection analysis of
The DTMF detection analyzer 17 sends the transmission end signal to the microcomputer 53 via the level converter 18. The microcomputer 53 sets the transmission permission state in response to the supply of the transmission end signal, and transmits the transmission permission signal accordingly. In this way, data communication between the host and the data communication terminal device 1 is performed, and when the microcomputer 53 detects an end signal for terminating the communication, the microcomputer 53 ends the data communication.

Further, the amplifier 16 is connected to a gain switching circuit 57 for switching a gain so that a DTMF signal having a signal level conforming to the regulation is generated and transmitted based on a control signal supplied from the microcomputer 53 in a transmission state. ing. Further, the data communication terminal device 1 in this embodiment can be connected to, for example, a fuel gas consumption meter, and the microcomputer 53 is connected to the consumption meter via the respective interfaces 58 and 59. Connectors 60 and 61 are connected. A connector 62 for writing data to a semiconductor memory provided in the microcomputer 53 is connected to the interface 58. The number and types of connectors are not limited to those described above.

The operation of the data communication terminal 1 according to the present embodiment having the above-described configuration will be described below. Normal,
Since the separator 50 has been switched to the "AUTO" side,
The home telephone is connected to a telephone line via a call detection circuit 8, a relay 52, and a filter 51. On the other hand, when a signal is supplied from the external device, for example, the above-mentioned gas consumption meter to the microcomputer 53 via the connectors 60, 61, etc., the microcomputer 53 transmits the information supplied from the consumption meter to the telephone line. Start preparing for transmission. That is, the microcomputer 53
Drives the call detection circuit 8 to determine whether or not a call is currently in progress. When it is determined that the user is not talking, the microcomputer 53 drives the relay 52 and switches the contact connected to the terminals 5 and 7 to the terminals 4 and 6 in the relay 52. By this switching, the telephone line and the data communication terminal device 1 are connected via the filter 51 and the relay 52.

The connection between the telephone line and the data communication terminal device 1 causes the telephone line to go off-hook, and the full-wave bridge circuit 10 connects to the telephone line via the line control circuit 9. Then, the DC / DC converter 11 connected to the output side of the full-wave bridge circuit 10 generates a 5V voltage with the power supplied from the telephone line, and applies the 5V voltage to the power supply selection switch 12.

On the other hand, since the microcomputer 53 detects the supply of data from the consumption meter, the microcomputer 53 sets a transmission permission state and sends a transmission permission signal to the power supply selection switch 12. Therefore, the power supply selection switch 12 applies a voltage of 5 V to the DTMF dialer 13, the low-pass filter 15, and the amplifier 16 to
TMF dialer 13, low-pass filter 15, amplifier 1
6 is driven. On the other hand, the power supply selection switch 12
The above-mentioned voltage is not applied to the DTMF detection analyzer 17, so that the DTMF detection analyzer 17 is in a non-operation state.

Next, the microcomputer 53 sends the information supplied from the consumption meter to the level converter 14 as 4-bit data, and the level converter 14 converts the supplied data into a voltage of 5V. DTMF dialer 13
Send to The DTMF dialer 13 creates a DTMF signal based on the supplied data, and sends the data as a DTMF signal. The DTMF signal transmitted from the DTMF dialer 13 is supplied to the amplifier 16 via the low-pass filter 15. The gain switching circuit 57 is controlled by the control signal supplied from the microcomputer 53 to the amplifier 16.
Is set to a predetermined gain, and the amplifier 16 amplifies the supplied DTMF signal at the set amplification factor, and amplifies the DTMF signal.
The MF signal is sent to the secondary side of the line transformer 54.

The turn ratio of the primary side and the secondary side of the line transformer 54 is 600 ohms to 600 ohms (1: 1), and the first resistor 55 connected to the output side of the amplifier 16
Is set to 220 ohms, which is smaller than the conventional 600 ohms, the signal level loss between the amplifier 16 and the line transformer 54 can be reduced, and the DTMF signal appearing on the primary side of the line transformer 54 can be reduced. Level can be made larger than before. still,
The impedance on the primary side of the line transformer 54 matches the impedance on the telephone line. Further, as described above, the DTMF detection analyzer 17 is in a non-operating state, and the resistance value of the second resistor provided at the input of the DTMF detection analyzer 17 is larger than the conventional 600 ohms.
Since it is 2K ohm, the input side of the DTMF detection analyzer is in a high impedance state. Thus, the level of the DTMF signal at the time of transmitting the DTMF signal can be easily secured. The DTMF signal transmitted from the line transformer 54 is transmitted to the telephone line via the line control circuit 9, the relay 52, the filter 51, and the divider 50.

A case where a DTMF signal returned from the host after the data transmission described above is supplied will be described. At this time, the relay 52 connects the telephone line and the line control circuit 9 as in the case of transmission. After the data transmission is performed as described above, the microcomputer 53 sets a reception permission state and sends a reception permission signal to the power supply selection switch 12. Therefore, the power supply selection switch 12
A voltage of 5 V is applied only to the DTMF detection analyzer 17,
TMF dialer 13, low-pass filter 15, amplifier 1
No voltage is applied to 6. Therefore, the DTMF detection analyzer 17 enters an operating state.

The DTMF signal transmitted from the host side and supplied from the telephone line via the divider 50, the filter 51, the relay 52, and the line control circuit 9 appears on the secondary side of the line transformer 54. When the DTMF signal is supplied, the amplifier 16 is in a non-operating state as described above, so that the amplifier 16 is in a high impedance state. further,
Further, as described above, since the resistance value of the second resistor provided at the input section of the DTMF detection analyzer 17 is larger than that of the related art,
The secondary side of the line transformer 54 enters a high impedance state. Therefore, the supplied DTMF signal is DTMF signal.
It can be transmitted to the MF detection analyzer 17 with a small loss. The primary side and the secondary side of the line transformer 54 are both 600 ohms.
Since the resistance values of the resistors are both 600 ohms, the present data communication terminal device 1 can obtain a gain increase of at least 6 dB as compared with the conventional device.

In this manner, the DTMF signal is supplied to the DTMF detection analyzer 17, and the DTMF detection analyzer 17
The transmission end signal attached to the TMF signal is detected, and the detection signal is sent to the level converter 18. Level converter 18
Converts the detection signal into a voltage of 3.6 V and sends it to the microcomputer 53. Thereby, the microcomputer 53 puts the data communication terminal device 1 into the transmission state again as shown in FIG. When the microcomputer 53 detects the end of communication provided in the DTMF signal supplied from the host, the microcomputer 53 detects the end of communication.
Ends the data communication.

As described above, in the data communication terminal device 1, since the DTMF dialer 13 and the like and the DTMF detection analyzer 17 are alternately supplied with power, the power consumption of the data communication terminal device is reduced. In particular, in a data communication terminal device of a type driven by a battery having a built-in DTMF dialer 13 and a DTMF detection analyzer 17, the operable time can be extended as compared with the conventional device. .

Since power is supplied alternately to the DTMF dialer 13 and the DTMF detector / analyzer 17, the DTMF dialer 13 and the DTMF detector / analyzer 17 do not operate at the same time. Can prevent the DTMF detection analyzer 17 from malfunctioning due to noise generated when the device operates.

[0026]

As described above in detail, according to the present invention, since the power supply selecting means is provided, the DTMF creation / transmission means or the DTMF detection / analysis based on the transmission permission signal and the reception permission signal supplied from the control means are provided. Since power is supplied to only one of the means, power consumption can be reduced.

Further, according to the present invention, power is supplied to only one of the DTMF creation / transmission means and the DTMF detection / analysis means, and the resistance value of the first resistor is set to the value of the line transformer. The impedance of the secondary transformer is made smaller than the impedance of the secondary side.
By making the impedance higher than the secondary side impedance, the transmission loss of the DTMF signal from the amplifier to the line transformer can be reduced during transmission, and the amplified DTMF signal can be transmitted to the telephone line with a small loss. Sometimes DTMF detection analysis means with little loss
Signals can be transmitted.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a data communication terminal device according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the data communication terminal device shown in FIG.

[Description of Signs] 9: Line control circuit, 10: Full-wave bridge circuit, 11: D
C / DC converter, 12 ... Power supply selection switch, 13 ...
DTMF dialer, 15: low-pass filter, 16: amplifier, 17: DTMF detection analyzer, 53: microcomputer, 54: line transformer, 55: first resistor, 5
6: Second resistor.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H03J 9/00-9/06 H04M 1/26-1/57 H04M 11/00-11/10 H04Q 1/30-1 / 50 H04Q 9/00-9/16

Claims (6)

(57) [Claims] 1. A line transformer having a primary side connected to a telephone line, a DTMF detection / analysis means connected to an input side of a secondary side of the line transformer, and detecting and analyzing a DTMF signal supplied from the telephone line. The output side is connected to the secondary side of the line transformer, and the DTMF indicating the data content.
DTMF creating and sending means for creating and sending a signal;
What is claimed is: 1. A data communication terminal device for transmitting a DTMF signal indicating the data content transmitted by said DTMF creation / transmission means using said telephone line via said line transformer, comprising: an output side of said DTMF detection / analysis means; The input side of the creation and transmission means is connected, sets a transmission permission state based on supply of data for transmission, and sets a reception permission state based on a data transmission end signal provided in the data. The transmission permission state is set based on the supply of the data transmission end signal supplied from the DTMF detection / analysis means, and the transmission permission signal or the reception permission signal is set to correspond to the transmission permission state or the reception permission state, respectively. Control means for transmitting, the input side is connected to the power supply means and the output side is the DTMF
Connected to the detection / analysis means and the DTMF creation / transmission means, and when the transmission permission signal is supplied from the control means, supplies power to the DTMF creation / transmission means and
No power is supplied to the TMF detection / analysis means, and when the reception permission signal is supplied from the control means, the DT
A data communication terminal device comprising: a power supply selection unit that supplies power to the MF detection analysis unit and does not supply power to the DTMF creation and transmission unit. 2. The DTMF generation and transmission means includes an DTMF dialer having an input side connected to the control means and generating a DTMF signal indicating data content based on data supplied from the control means, and an output side of the DTMF dialer. 2. The data communication terminal device according to claim 1, further comprising an amplifier connected in series with a secondary side of the line transformer and amplifying the DTMF signal transmitted by the DTMF dialer. 3. The data communication terminal device according to claim 1, wherein said power supply means is said telephone line. 4. The data communication terminal device according to claim 1, wherein said power supply means is a battery provided in said data communication terminal device. 5. A first resistor connected in series between a connection point between a secondary line of the line transformer and an input line of the DTMF detection / analysis means and an output of the amplifier; A second resistor connected in series to the input side line of the means, wherein the impedance of the line transformer on the primary side and the secondary side is 600 ohms,
The resistance value of the first resistor is less than 600 ohms,
The data communication terminal device according to any one of claims 2 to 4, wherein a resistance value of the second resistor is a value exceeding 600 ohms. 6. The data communication terminal device according to claim 5, wherein the resistance value of the first resistor is 220 ohms, and the resistance value of the second resistor is 22 K ohms.