JPH04290345A - Cordless loud-speaker telephone set - Google Patents

Abstract

PURPOSE:To enable inexpensive mutual simultaneous calling without fail by linking an antenna conductor with an opened acoustic waveguide tube to the sound collection hole of a receiver microphone through an insulating distance tube at a base part of a box body installation. CONSTITUTION:With the uniform acoustic waveguide tube diameter by a tube antenna electric conductor 20, the acoustic transmission loss is small and the built-in microphone 21 can collect sounds located in the opening edge of the antenna conductor 20. In short, the sound collection sensitivity of the microphone 21 for caller voice is high, and the sound collection sensitivity for a distant receiver speaker 11 is low. Thus, echo and howling generation can be suppressed as well as transmission sound collection S/N can be improved. The antenna gain and radiation efficiency of radio waves from antenna can be improved by the radial counterpoise conductive of leg parts 9a to 9c.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a cordless telephone handset, and in particular, it is not a portable type, but a tabletop type, and is equipped with a built-in receiver speaker and a tubular or horn-shaped antenna protruding from the outside of the housing. This invention relates to a cordless loudspeaker telephone that allows hands-free calling using a transmitting microphone provided on the conductor base.

0002

[Prior Art] A device (base unit) equipped with a low-power wireless transmitter/receiver and connectable to a telephone line; Cordless telephones consist of a pair of handset-type mobile units (child units) that can communicate wirelessly without the need for cords to get in the way.
Telephone calls can be made from anywhere in the home, such as in the room or the garden, and their popularity has accelerated in recent years due to their convenience.

[0003] These conventional cordless telephones are originally intended for portable use, and are of the so-called handy transceiver type in which the antenna protrudes from the housing. And I haven't seen anything that is semi-stationary and has a hands-free calling type.

[0004] On the other hand, there are portable radios that have a built-in speaker in their casings that allow them to transmit and receive amplified calls, but such devices are generally of the press-to-talk type, meaning that they can transmit and receive calls at the same time. It cannot be done.

[0005]

[Problems to be Solved by the Invention] By the way, a large number of wired (corded) hands-free telephones have been commercialized. These conventional hands-free telephones have a speaker and a microphone housed in the telephone housing, making them easy to use like an intercom. The transmitting microphone picks up the voice of the other party from the nearby speaker louder than the voice of the person speaking who is far away (approximately 50 cm) from the microphone. be done. As a result, there is a problem in that the received voice returns via the telephone line and causes howling and echoes, causing communication failure.

[0006] In order to solve this problem, in the past, it was necessary to adopt an alternate call system using a voice control switch, which makes it difficult to avoid problems such as interruptions at the beginning or end of a call, or an echo canceller system, which requires high construction costs.

Therefore, the present invention takes into account the problems of the prior art, and provides a wireless hands-free loudspeaker telephone that is inexpensive and capable of reliably communicating simultaneously without the need for a special circuit system as described above. The primary purpose is to provide.

[0008] Conventional hands-free telephones have also been designed to have a good appearance, with the transmitting microphone being mounted on the desk surface or in a location close to the desk surface, resulting in poor transmitting acoustic characteristics and pickup S/N ratio. was not always good.

A second object of the present invention is to provide a hands-free loudspeaker telephone with good transmitting and receiving acoustic characteristics. By the way, in a portable cordless telephone, the hand or human body that grips the main body acts to promote the grounding effect, and if the telephone is not held in the hand, the radiation efficiency of radio waves decreases and it is difficult to obtain a good reception gain. Taking these points into consideration, the third object of the present invention is to provide a cordless loudspeaker telephone that can obtain excellent radio wave radiation and good reception gain even though it is a desk-top type telephone.

0010

Means for Solving the Problems FIG. 1 is a block diagram showing a cordless loudspeaker telephone according to the present invention. In the figure, the cordless loudspeaker telephone has a housing 7, and inside the housing 7, wireless transmitting/receiving circuits 10a and 10b are provided. Further, a tubular or horn-shaped antenna conductor 20 extending outward is held in the housing 7 via an insulating spacer tube 22, and this insulating spacer tube 22 is connected to a sound collection hole of a microphone 21. That is, the tubular antenna conductor 20 is configured to play the role of an acoustic waveguide that guides sound from the tip of the opening to the built-in microphone 21. In terms of high frequency, they are separated by the insulating spacing tube 22.

[0011] Furthermore, the leg portions 9a, 9b, 9c of the housing 7
is composed of a radial counterpoise conductor, and the wireless transmission
It is connected to the ground circuit of the receiving circuits 10a and 10b to increase the gain of the antenna and the radiation efficiency of radio waves from the antenna.

0012

[Function] When the diameter of the acoustic waveguide formed by the tubular antenna conductor 20 is uniform, the acoustic transmission loss is small, and the built-in microphone 21 is connected to the tubular antenna conductor 2.
Sound can be collected as if it were at the tip of the opening. That is,
The microphone 21 has high sound collection sensitivity for the voice of the caller, and has low sound collection sensitivity for the receiving speaker 11 located in a far position. Therefore, the occurrence of echoes and howling can be suppressed, and the S/N ratio of transmitted and collected sound can be increased.

Furthermore, the radial counterpoise conductors of the legs 9a, 9b, and 9c can improve the gain of the antenna and the radiation efficiency of radio waves from the antenna.

[0014]

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 is a schematic diagram of a hands-free cordless telephone system including a cordless public address telephone according to the present invention. In the same figure,
The base unit 1 and the handset 2 are configured to be able to talk to each other simultaneously using radio waves. The base unit 1 has a transmitting circuit 3, a receiving circuit 4, a line control circuit 5, etc., and the line control circuit 5 is connected to a central office (C.O.) 6 or a private branch exchange (PB) via a telephone line.
X) Connected to 6.

The handset 2 configured as a cordless loudspeaker telephone has a housing 7, and the housing 7 includes a tubular antenna conductor 20 extending outside and legs 9 (9a, 9b, 9c).
and a protrusion that also serves as a counterpoise.

A transmitting/receiving circuit 10 and a receiver speaker 11 are provided in the housing 7, and the receiver speaker 11 has its sound emitting port directed toward the lowest part between the legs 9, and emits the sound onto a table top surface or the like. I'm trying to make a sound. A microphone 21 is fixed to the base of the antenna conductor 20.

[0017] Then, the base unit 1 is connected to the telephone office (C.O.
．． ) 6 or the private branch exchange (PBX) 6, the line control circuit 5 maintains the line connected to the incoming call detection circuit 13. When there is an incoming call from the central office (C.O.) 6 or the private branch exchange (PBX) 6, the incoming call detection circuit 1
3 detects this and outputs a calling signal to the modulation signal input of the transmitting circuit 3. A modulated wave (carrier wave) is modulated by this calling signal, and a transmission signal fD (downlink signal) propagates through space from the antenna 15 via the transmission/reception antenna common circuit 14. The transmission signal fD is induced in the antenna conductor 20 of the handset 2 and guided to the receiving circuit (RX) of the transmitting/receiving circuit 10. The receiving circuit (RX) reproduces the calling signal, and the receiving speaker 11 emits the calling signal. When the handset 2 side performs a response operation, a response signal is output to the modulation signal input of the transmitting circuit (TX) of the transmitting/receiving circuit 10, as in the case of the base unit. As a result, the modulated transmission signal fU (uplink signal) from the handset side propagates through space. The transmission signal fU is induced in the antenna 15 of the base unit 1 and guided to the reception circuit 4. The receiving circuit 4 reproduces the response signal and transmits it to the line control circuit 5, which allows the line side and the handset 2 side to talk to each other at the same time. Thereafter, the content of the call on the handset 2 side is transmitted to the receiver of the other party via the uplink signal and the telephone line, and the content of the call of the other party is transmitted from the receiver speaker 11 via the telephone line and the downlink signal fD. I can start hearing it. When calling the other party from the handset 2 side, a calling signal is sent and dialing is performed from a transmission circuit 16 (which may be provided on the handset side) such as a so-called DTMF. Further, the base unit is equipped with a hybrid circuit 17 for using the two-wire line for both transmission and reception.

FIG. 3 is a block diagram showing a first embodiment of the present invention. In the figure, a tubular antenna 20 made of a metal conductor is provided on the top of the housing 7, and a portion slightly away from the attachment point to the housing 7 is mounted diagonally so that its tip is located near the mouth of the person making the call. It is bent.

The tip of the tubular antenna 20 is open, and a sponge-like microphone cap 23 is provided to prevent wind noise from occurring and the saliva of the speaker from entering. Further, the entire tubular antenna 20 is configured to be rotatable 24 so that the speaker can transmit from any position. In addition,
The tubular antenna 20 can also be formed using a bendable spiral tube.

The tubular antenna 20 serves as an original antenna conductor and an acoustic waveguide, and is fixed to the housing 7 via an insulating spacer tube 22 that also serves as a bushing. An ultra-small microphone 21 is provided at the bottom of the insulating spacer tube 22, and the sound hole (microphone's sound collection hole) is used to acoustically terminate the microphone. Furthermore, the output audio current (AF) of the microphone 21 is directly guided to the modulation circuit of the transmission circuit 10a.

The legs 9a, 9b, 9c of the housing 7 are made of radial counterpoise conductors, and are connected to the ground circuit of the radio transmitting/receiving circuits 10a, 10b to adjust the gain of the antenna and the radiation of radio waves from the antenna. Improving efficiency.

FIG. 4 is a block diagram showing the main parts of a second embodiment of the present invention. In the same figure, two rows of small holes 25 are bored in the wall of a tubular antenna 20a at approximately equal intervals in the longitudinal direction. Tubular antenna 20a with this small hole 25
When sound from an oblique direction other than toward the ultra-small microphone 21 from the tip opening is guided to the small hole 25, it is canceled by the phase difference due to the sound path difference, so it operates as a highly directional line microphone. Note that the inside of the tube may be filled with an acoustic resistor such as a nonwoven fabric. The other configurations are the same as those described above.

FIG. 5 is a block diagram showing the main parts of a third embodiment of the present invention. In the figure, the antenna conductor 20b is formed into a horn shape. By forming the microphone 21 into such a shape, the efficiency of collecting sound from the opening is significantly increased, so that the microphone 21 can be operated with low sensitivity. Therefore, it is difficult to pick up the direct vibration of the housing caused by the speaker, and it is also difficult to pick up noise from the side, and the transmission S/N is improved. In addition, since the conductor area gradually increases toward the tip of the antenna, in combination with the counterpoises 9a, 9b, and 9c of the tripod, it functions just like a biconical antenna, and can enjoy broadband characteristics. Therefore, the uplink and downlink frequencies are 250MHz
Efficient transmission and reception can be performed even if the frequency is nearly twice as far away, such as /380MHz. The other configurations are the same as those described above.

[0024]

As described above in detail, according to the present invention, it is possible to obtain a wireless hands-free loudspeaker telephone that is capable of reliably communicating simultaneously without causing howling or echo. In addition, it is possible to obtain excellent radio wave radiation and good reception gain even though it is a tabletop type, and
A hands-free loudspeaker telephone with excellent transmitting and receiving acoustic characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a cordless loudspeaker telephone according to the present invention.

FIG. 2 is a schematic configuration diagram of a hands-free cordless telephone system including a cordless public address telephone according to the present invention.

FIG. 3 is a configuration diagram showing a first embodiment of the present invention.

FIG. 4 is a configuration diagram showing main parts of a second embodiment of the present invention.

FIG. 5 is a configuration diagram showing main parts of a third embodiment of the present invention.

[Explanation of symbols]

7 Housing 9 legs 10 Transmission/reception circuit 20 Tubular antenna 21 Microphone 22 Insulated interval tube

Claims (4)

[Claims] [Claim 1] A wireless transmitter/receiver circuit and an earpiece speaker are provided in the housing, and extend outward from the housing,
Further, an antenna conductor is provided which is guided to the radio transmitting/receiving circuit, and the antenna conductor has the shape of an acoustic waveguide with an open end, and a transmitting microphone is connected through an insulating spacer tube at a mounting base of the antenna conductor to the housing. A cordless public address telephone characterized by being connected to a sound collection hole. 2. The cordless loudspeaker telephone according to claim 1, wherein the antenna conductor has a line microphone structure with an open end and small holes bored at approximately constant intervals in the tube wall. 3. The cordless loudspeaker telephone according to claim 1, wherein the antenna conductor has an acoustic horn shape with an open end. 4. The cordless loudspeaker telephone according to claim 1, wherein the housing is provided with a counterpoise guided to a ground circuit of the radio transmitting/receiving circuit.