DE950200C - Telephone handset with talk button to prevent unwanted eavesdropping - Google Patents

Description

Telephone handset with push-to-talk button to prevent unwanted Eavesdropping The invention relates to telephone handsets with push-to-talk buttons for portable Telephone sets with OB operation to prevent unwanted eavesdropping.

In the case of portable telephones with OB operation, the handset is in the idle position is placed on the device housing, the handset is equipped with a so-called Talk button equipped, through which the microphone circuit when the handset is put down is interrupted. This on the one hand protects the feed battery and on the other hand prevents unwanted eavesdropping. The phone is still in a more direct position electrical connection with the outgoing line This means that the earpiece acts as a sound receiver even when the handset is put down. She provides that Microphone of a battery-free telephone system. This effect becomes special very clear when using loud phone capsules.

To avoid this secret possibility of eavesdropping, the telephone capsule just like the microphone can be switched off. This can be done with telephones with OB operation, which are equipped with a hook switch, in a known manner by a. additional contact, which is actuated by the fork holder and the Telephone circuit disconnects.

In telephones with a push-to-talk button, the push-to-talk button is used for the same purpose another contact is assigned through the microphone circuit at the same time the telephone circuit is switched on or off. In another known arrangement this type is activated by the additional push-to-talk button. Contact a the phone upstream attenuator switched off or on. Because the push-to-talk button of this well-known speakerphone with the handset held free does not go beyond its support level, exists for the actuation of the contacts only one direction of movement, d. H. only make or break contacts can be used There is therefore the disadvantage of the known arrangement that while the talk button has to be pressed continuously during the whole conversation. Furthermore is in this case the possibility of so-called open listening is not given, d. H. the microphone cannot be switched off for the time when only listening is required, so that the room noises are picked up by your own microphone and the communication is disabled.

The invention aims to avoid these disadvantages. You achieved This is because the pressure surface of the push-to-talk button when the handset is free protrudes beyond the support surface of the same, so that thereby a contact spring set is operated in three switching positions, of which the middle, in which both the The microphone and telephone circuit are interrupted when the handset is on-hook is forced, and that in the outer switch position only the telephone circuit in which When the inner switch position is pressed, the telephone and microphone circuits are closed are. According to a further development of the invention, the Ko.ntaktfeder@satz consists of a Umsahaltekontakt, whose outer contact springs are connected in parallel and whose working page has an additional. Normally open contact switches as a follow-up contact. The distance between the push-to-talk button in its outer switch position and the Support plane of the handset corresponds to a further embodiment of the invention the way that the middle contact spring of the changeover contact must perform to to come to the middle position between the two outer contact springs.

The invention is based on a principle example in FRg. i to 3 explained in more detail. There b edeutet Fig. For the switching position of the talk key at the handset held free, Fig. 2 shows the switching position of the speech key while the handset, Fig. 3 shows the switching position of the .gedrückten talk button.

The figures. only represent those parts of the handset in principle that are absolutely necessary to understand the invention. The handset 3 shown schematically has at the point where it is placed on the support device 8, usually the housing of the telephone, three support prongs 2, of which only two are shown. The tips of these prongs: 2 lie in the support plane 2 ″ of the handset 3. Between these is the talk button, which plunges into the handset 3 when pressed. The talk button i actuates the middle contact spring 4 of a changeover contact via a web ib Outer contact springs 4Q and 4b of this changeover contact are electrically connected in parallel - the middle contact spring 4 tends to push the talk button i outwards out of the handset 3. This ensures that the talk button i almost completely out of the handset 3 when the handset is held free protrudes (Fig. i). The pressure surface i ″ of the push-to-talk button i protrudes beyond the tips of the support prongs 2, namely by the amount 9 which corresponds to the path that the switching spring 4 must take to move out of its rest position (Fig. i) to get into the middle position (Fig. 2) between the two outer springs 4 ″ and 4b of the changeover contact. In this middle position b there is no contact between the changeover contact spring 4 and the two outer 4 "and 4b, so that the telephone circuit F, F 'of the telephone capsule 6 is interrupted. The outer contact spring 4b on the work side is connected to the contact spring of an additional work contact 5 by an insulating piece io, so that when the talk button i is pressed, the additional work contact 5 is closed at the same time as the work side 4, 4b of the changeover contact is closed (Fig. 3). The M, M 'for the microphone 7 is closed by this normally open contact 3. In the pressed position of the talk button i, both the microphone circuit M, M 'and the telephone circuit F, F' are closed. If both spoken a; ls are to be heard, the speak button must therefore be pressed so that it is practical comes to lie within the handset.

With the handset held free, i. H. at the outermost switch position the talk button 1 is, as can be seen from Fig. i, the telephone circuit F, F 'above the contacts 4 and 4 "of the Umsohaltekontakts closed., while the microphone circuit M, M 'is interrupted by contact 5. It can therefore in this switch position only be heard, d. H. so-called open listening is possible because the room noises are not recorded and transmitted by their own microphone.

In Fig. Z, the middle switch position of the push-to-talk button is shown, which is achieved when the handset is placed on the support 8 in the rest position is. Both the microphone circuit M, M 'and the telephone circuit F, F' are in this Switch position separated.

Due to the possibility that the push-to-talk button has three switch positions, can forcibly by combining a changeover contact with one of these operated normally open contact can be achieved in a simple and cheap manner that over the telephone 6 an unwanted eavesdropping is avoided and at the same time the possibility of hearing can be improved by releasing the talk button.

Claims (5)

PATENT CLAIMS: i. Fernsprechhandapparat.mit speech button for portable telephones with OB operation to prevent unwanted eavesdropping, characterized in that the pressure surface (ra) of the speech button (z) protrudes beyond the support surface (2a) of the same when the handset (3) is held free, so that a Contact spring set (4, 5) is actuated in three switch positions, of which the middle one, in which both the microphone and the telephone circuit (M, M 'and F, F') are interrupted, is forced when the handset (3) is on-hook, and that in the outer switch position only the telephone circuit (F, F '), in the pressed inner switch position the telephone and microphone circuit are closed. 2. Telephone handset according to claim z, characterized in that the middle switch position of the speech button (z) by the height of the lying in the support plane (2d) of the handset (3) Support prongs (2) is determined. 3. Telephone handset according to claim r and 2, characterized in that the contact spring set consists of a changeover contact (4, 4 "4a), through which a working contact is compulsory in the working position (5) is operated. 4. Telephone handset according to claim r to 3, characterized in that that the two outer contact springs (4a, 4a) of the changeover contact are electrical are connected in parallel. 5. Fernsprechhandappai # at according to claim z to 4, characterized characterized in that the distance (9) of the push-button push-button surface (ra) in its outer The switching position of the support level (2 ¢) corresponds to the path taken by the middle contact spring (4) of the changeover contact must run in order to be in the middle position between the two outer contact springs (4a, 4a) to come.