Patent GB-278833-A (GB)
Title: Improvements in or relating to telephone transmitters
IPC: H04R1/14
Filed: 1926-08-04
Abstract: 278,833. Rickets, W. J., and Smith, E. E. Aug. 4, 1926. Head, throat, and breast sets.-Relates to telephone transmitters of the kind adapted to bear against the part of a speaker affected by vibrations of the vocal organs and consists in associating with the transmitter, circuit closing means adapted normally to break an electric circuit and so arranged that the act of pressing the throat against the transmitter, or vice versa, will actuate the circuit closing means and cause one or more telephonic circuits, including the transmitter, to be closed. If desired, a calling or bell circuit may be adapted to be opened at the same time. The invention is described as applied to a transmitter of the kind described in Specification 270,088, in which the portion designed to bear against the speaker's throat is formed as a hollow body or pad of resilient material filled with a deformable or incompressible sound transmitting medium, the inner end of the hollow body being connected to the movable electrode of the microphone. In the construction, Fig. 1, the transmitter is held endways in its normal position in the casing 2 by a spring 3, the casing being provided with an electric switch, the movable member 4 of which is normally held by spring action against the contact 6 so as to close a calling or bell circuit. On pressing the end 1<a> of the transmitter against the throat, the transmitter is moved endways in the casing 2 against the spring 3, causing the member 4 to open the calling circuit and engage with the contact 5 to close a speaking circuit through the transmitter. Fig. 2 shows a construction in which the transmitter 1 is mounted at one end of a lever 7 pivoted at 7a in a support 8, the other end 7b of the lever being normalJy pressed by a spring 11 against a contact 10 so as to close a calling circuit. The act of pressing the transmitter against the throat causes the lever to rock on its pivot against the spring 11 thereby opening the calling circuit and closing a speaking circuit through the contact 9. In a modification, Fig. 3, the outer wall 12a of the resilient pad 12 of the transmitter is provided with a cavity 13 in which are located two insulated spring contacts 4a 5a connected to two portions of an electric circuit. The outer side of the cavity 13 is provided with a resilient covering 14 having on its inner surface a projection 14a of insulating material arranged to press inward against the contact 4a and force it against the contact 5<a> when the transmitter is applied against the throat. According to a further modification the wall of the fluid filled pad 12 remote from the wall 12a is formed with a portion made thinner than the remainder so as to render it more flexible, one terminal of a speaking circuit being attached to or arranged close to the outside of this thin portion and adapted to make contact with a second terminal when the thin portion is deformed under the influence of pressure within the pad. In a still further modification, Fig. 4. a nipple 15, carried by the rear wall 12b of the pad 12 and communicating with the fluid within the pad, is expanded by the fluid when the transmitter is applied for use so as to cause an external contact 16, formed as a thin sheet metal split ring, to move outwards and contact with terminals 4b, 5b to close the speaking circuit. Instead of the contact arrangement 16, 4<b>, 5<b>, a pair of contacts normally separated may be arranged outside of but near to the nipple so that, when the latter expands, the two contacts will be pressed together to close a circuit. The casing of the transmitter may be provided with means for supporting it from the head of the user.