JPH0481908B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a telephone handset, and more particularly to a telephone handset having a high performance speaker.

[Conventional technology]

Conventional telephone handsets use electromagnetic handsets, and have frequency characteristics that allow voice signals at the transmission frequency of the telephone line to be repeated.

[Problems to be solved by the invention] In recent years, electrodynamic speakers and piezoelectric speakers have been applied to telephone handsets, but these handsets have wider frequency characteristics than conventional telephone handsets. It also has good linearity in input/output level characteristics and a wide dynamic range, so it faithfully reproduces ambient noise caused by telephone line noise and echoes from the transmitter (hereinafter referred to as sidetone).
This has the disadvantage that it is difficult for the listener to hear the voice from the other party, that is, the clarity of the call is reduced.

[Means for solving problems]

The telephone handset of the present invention includes a speaker, a narrowband three-wave circuit that uses the reception output of the telephone communication circuit as an input signal, and has frequency characteristics that prevent the reception of noise and at least allow the voice of the other party to be understood;
A high-level detection circuit detects high-level input that causes an excessive acoustic shock to the listener; a low-level detection circuit detects low-level input that includes at least a noise level; and a predetermined level output circuit that automatically suppresses and outputs the level to a predetermined audible level; and a predetermined level output circuit that switches the receiving output of the speech circuit to the predetermined level detection circuit when receiving the detection output of the high level detection circuit. and a second switching circuit that, when receiving the detection output of the low level detection circuit, switches the reception output of the communication circuit to the output of the narrowband three-wave circuit and outputs it to the speaker. There is.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a functional block diagram showing one embodiment of the present invention.

The telephone handset 9 connected to the telephone circuit 1 is
It has a speaker (electrodynamic type or piezoelectric type) 8, a predetermined level output circuit 2, a narrowband three-wave circuit 3, a high level detection circuit 4, a low level detection circuit 5, and switching circuits 6 and 7.

The receiving output of the communication circuit 1 is normally directly connected to the speaker 8 through the switching circuit 6 and the other party's voice can be heard. The reception output of the communication circuit 1 is input to the narrowband three-wave circuit 3. This narrowband three-wave circuit 3 has a pass band of the audio band from 1 kHz to 3 kHz. When the high level detection circuit 4 detects that the output of the narrowband three-wave circuit 3 is at an excessive level (signal level corresponding to the sound pressure of the speaker 8 being 94 dB _SPL or more), it drives the switching circuit 6. By this driving, the switching circuit 6 is switched from the normally connected state to the predetermined level output circuit 2 and connected. The predetermined level output circuit 2 receives the reception output of the communication circuit 1 as an input, and has an automatic gain adjustment function that suppresses the output level to a predetermined constant value even if the input signal level changes. On the other hand, the low level detection circuit 5 has the output of the narrowband 3-wave circuit 3 set as the threshold value.
When a signal level corresponding to a sound pressure smaller than 55 dB _SPL is detected, the switching circuit 7 is driven. By this driving, the switching circuit 7 switches the speaker 8 from the normally connected state to the output of the narrowband three-wave circuit 3 and connects it.

Therefore, the sound pressure output from the speaker 8 is
When it is 94dB _SPL or higher, the sound pressure is suppressed and output. In addition, when the sound pressure is below 55dB _SPL , only the band from 1kHz to 3kHz is output, and output sound pressures exceeding 55dB _SPL and up to 94dB _SPL are faithfully output.

In this embodiment, the set levels of the detection circuits 5 and 4 have been described as corresponding to sound pressures of 55 dB _SPL and 94 dB _SPL , but the present invention is not limited to these values.

〔Effect of the invention〕

As explained below, the telephone handset of the present invention protects the listener by suppressing excessive level input that would cause an excessive acoustic shock to a predetermined level of sound pressure, and also protects the listener with a narrow band for low sound pressure input. By removing noise from the telephone line and surrounding noise from those on the other side through the three-wave circuit, the clarity of the call can be significantly improved.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing one embodiment of the present invention. 1... Call circuit, 2... Predetermined level output circuit,
3...Narrowband 3-wave circuit, 4...High level detection circuit, 5...Low level detection circuit, 6, 7...Switching circuit, 8...Speaker, 9...Telephone receiver.

Claims (1)

[Claims] 1 A speaker, a narrow-band 3-wave circuit that uses the receiving output of the phone's communication circuit as an input signal and has a frequency characteristic that prevents the reception of noise and at least allows the other party's voice to be understood, and a narrow-band 3-wave circuit that uses the reception output of the telephone's communication circuit as an input signal and has frequency characteristics that allow the listener to at least understand the voice of the other party. a high level detection circuit that detects a high level input, a low level detection circuit that detects a low level input that includes at least a noise level; a predetermined level output circuit that automatically suppresses and outputs a low level; a first switching circuit that switches the reception output of the speech circuit to the predetermined level output circuit when receiving the detection output of the high level detection circuit; and a second switching circuit that switches the reception output of the communication circuit to the output of the narrowband 3-wave circuit and outputs it to the speaker when receiving the detection output of the low level detection circuit. .