JPH01293749A - Signal sending level switching device for telephone set - Google Patents

Abstract

PURPOSE:To surely switch a signal sending level without a manual operation by detecting the polarity inversion of d.c. voltage in a line when a response to the reception of a selecting signal is received after the selecting signal is sent and switching the signal sending level based on the detected result. CONSTITUTION:When the selecting signal is sent and the response from a called side is received, at a calling side, the polarity of the DC voltage in terminals L1 and L2 is inverted by an exchange. The polarity inversion is detected at a reverse detecting circuit 55, a switching control circuit 56 for the selecting signal and a data communication signal is switch-controlled by the output of the circuit 55, and a fixed resistance attenuator 53 at the side of the data communication signal is automatically set. Consequently, a dial signal generated after that is made into a level for the data communication signal at the attenuator 53 and sent through a coupling capacitor 54, a diode bridge 2, and the terminals L1 and L2 to a telephone line. Thus, since the signal sending level can be automatically switched based on the output of the circuit 55, the sending level of the dial signal can be surely switched without the manual operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a signal output level switching device in a push-button telephone.

(Prior art) In telephones that use push-button dialing signals,
Push-button dialing signals are often used not only as selection signals for selecting a subscriber, but also as signals for data communications.

However, the signal transmission level regulations in the "Terminal Equipment Regulations" (Ministry of Posts and Telecommunications Ordinance No. 31) based on Article 46 of the Telecommunications Business Act clearly define the level to be transmitted as a selection signal and the level to be transmitted as a data communication signal. are differentiated,
Moreover, the transmission levels are also significantly different. This signal transmission level regulation is shown in FIG. Figures (a) and (b) define the push button signals for the low group and high group that are generated in response to the push buttons, respectively, and the range specified by Article 11 and the range specified by Article 13 are the selection signals, respectively. This is the specified range for communication level and data communication level. Therefore, the push-button telephone is equipped with a transmission level switching device for switching these transmission levels.

FIG. 3 is a block diagram showing an example of the configuration of a telephone having a conventional level switching device.

In the figure, Ll and L2 are telephone terminals connected to the telephone line, 1 is a hook switch, 2 is a polarity matching diode bridge, 3 is a push button switch, 4 is a push button dial signal generation circuit, and 5 is a signal output level. switching device,
6 is a communication circuit, 7 is a receiver, 8 is a transmitter, 9 is a tone ringer circuit, and 10 is a sounding body. The signal transmission level switching device 5 includes a lock type switch 51 for selecting a selection signal/data communication signal, a fixed resistance attenuator 52 for adjusting the selection signal level,
It consists of a fixed resistance attenuator 53 for data communication signal level adjustment and a coupling capacitor 54.

Next, the operation will be explained.

When the hook switch 1 is raised to make a call (the position is opposite to that shown), the DC voltage from the exchange is full-wave rectified by the polarity-matched diode bridge 2, and then passed through the push button dialing signal generation circuit 4 and the calling circuit 6. supplied to When a desired push button switch 3 is pressed here, the push button dial signal generation circuit 4 generates one frequency signal for each of the low group and high group corresponding to the pressed button. At this time, the fixed resistance attenuator 52 or 5 for signal level adjustment according to the setting of the selection signal/data communication switching lock switch 51
3 is connected to the output of the push button dial signal generation circuit 4, and each is adjusted to an appropriate level and connected to the coupling capacitor 54, the diode bridge 2 and the telephone terminal Ll,
It is sent to the telephone line via L2.

(Problem to be Solved by the Invention) However, in the level switching device 5 having the above configuration, the user must operate the selection signal/data communication switching switch 51 each time the selection signal is sent out and the data communication is started. However, there has been a problem in that an excessively high signal level is sometimes transmitted during data communication, and conversely, an excessively low signal level is sometimes transmitted when transmitting a selection signal. Furthermore, after the data communication is completed, it is necessary to return to the settings at the time of sending the selection signal, which poses a problem of poor operability.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems and provide a signal transmission level switching device for a telephone that can reliably switch the signal transmission level without manual operation.

<:! Means for Solving Problem 1) In order to solve the above-mentioned problems, the present invention provides a first means for setting the transmission level of a dial signal generated in response to a pressed button to a selection signal level; In a signal transmission level switching device for a telephone that includes a second means for setting the transmission level to a data communication signal level and selectively switches these, the polarity of the DC voltage of the line is inverted when responding to an incoming call after transmission of the selection signal. The apparatus is provided with a detection means for detecting the detection means, and a switching means for performing the switching based on the detection result of the detection means.

(Operation) The technical means of the present invention operates as follows. Detection means (
For example, the reverse detection circuit (described later) is configured to output a signal for selecting the first means (for example, a resistive attenuator, etc.) to the switching means in the initial setting state. As a result,
The switching means (for example, a switching control circuit to be described later) selects the first means, and the first means operates to change the sending level of the dial signal (push button dial signal) to the selection signal level and output it as the selection signal. . After sending the selection signal, when the other party detects an incoming call and responds, the exchange performs a polarity reversal of the DC voltage of the line, and when the detection means detects this polarity reversal, the detection means uses a second means (for example, resistive attenuation). It functions to output a signal to the switching means to select the device. As a result, the switching means selects the second selection means, and the second means operates to change the sending level of the dial signal to a data communication signal level and output it as a data communication signal. Thereafter, the detecting means controls the switching means by the on-footer to select the first means and set it in the initial setting state. In this way, since the transmitting level is switched based on the detection result of the polarity reversal of the DC voltage of the line, the problems of the prior art described above can be solved.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the present invention, and is a block diagram of a telephone having a signal output level switching device according to the present invention. In this figure, the same reference numerals as in FIG. 3 indicate the same components. The signal transmission level switching device 5a of this embodiment includes a reverse detection circuit inserted between the terminal L2 and the diode bridge 2, in addition to the fixed resistance attenuators 52, 53 and the coupling capacitor 54 similar to those shown in FIG. 55 and a fixed resistance attenuator 52 .
53 and a selection signal/data communication signal switching control circuit 56. The selection signal/data communication signal switching control circuit 56 is composed of semiconductor switching elements, etc., and is set to the selection signal sending side (fixed resistance attenuator 52) in the initial setting state (standby state and call unanswered state). .

Next, the operation of this embodiment will be explained.

First, when hook switch 1 is raised to make a call (the position is opposite to that shown in the figure), the DC voltage from the exchange is full-wave rectified by polarity matching diode bridge 2, and the push button dial signal generation circuit 4 is placed on the right side to make a call. It is supplied to circuit 6.

When the push button switch 3 is pressed here, the push button dial signal generation circuit 4 generates one frequency signal each for the low group and the high group corresponding to the pressed button. As mentioned above, the selection signal/data communication signal switching control circuit 56 is set to the selection signal sending side (fixed resistance attenuator 52) at this time, and the generated dial signal is sent to the fixed resistance attenuator 5.
2 to the selection signal level, and as a selection signal, the coupling capacitor 54, the bridge 2 and the telephone terminals Ll, L2
is sent out to the telephone line via .

On the other hand, when there is a response from the called side, the exchange reverses the polarity of the DC voltage at terminals L1 and L2 on the calling side. Therefore, this polarity reversal is detected by the reverse detection circuit 55,
The output (for example, "1") controls the selection signal/data communication signal switching control circuit 56 to automatically set the data communication signal side (fixed resistance attenuator 53). Therefore, the dial signal generated thereafter is made to the level for a data communication signal by the fixed resistance attenuator 53, and the data communication signal is connected to the coupling capacitor 54, the diode bridge 2 and the terminal L.
1, sent to the telephone line via L2. After the end of the call or data communication, the reverse detection circuit 55 is restored by the on-footer (the hook switch 1 is in the position shown in the figure), and its output becomes "0", for example. As a result, the selection signal/data communication signal switching control circuit 56 is in the initial setting state (
fixed resistance attenuator 52 side).

In this way, in this embodiment, the user does not have to operate the selection signal/data communication switch each time,
Since automatic switching is possible based on the output of the reverse detection circuit 55, it is possible to provide a signal sending level device for a telephone that is reliable and has excellent operability.

In the above embodiments, the switching is performed on the input side of the fixed resistance attenuators 52, 53, but it is clear that the switching may be performed on the output side.

(Effects of the Invention) As described above in detail, according to the present invention, the dial signal transmission level is switched based on the detection result of the polarity reversal of the DC voltage of the line, so the dial signal transmission level can be switched reliably without manual operation. You can change the dial signal transmission level.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a signal transmission level regulation diagram according to Ordinance No. 31 of the Ministry of Posts and Telecommunications, and Fig. 3 is a block diagram of a telephone equipped with a conventional signal transmission level switching device. . 5a-Signal sending level switching device, 52.53-Fixed resistance attenuator, 54-Coupling capacitor, 55-Reverse detection circuit, 56-Switching control circuit. Patent applicant: Oki Electric Industry Co., Ltd. Patent application agent: Patent attorney Megumi Yamamoto

Claims (1)

[Claims] First means for setting the transmission level of a dial signal generated in response to a pressed button to a selection signal level, and second means for setting the transmission level to a data communication signal level. A signal transmission level switching device for a telephone set that selectively switches these, comprising: a detection means for detecting a polarity reversal of the DC voltage of the line when responding to an incoming call after sending a selection signal; 1. A signal transmission level switching device for a telephone set, comprising: switching means for performing the switching.