FR2486736A1 - RADIO RECEIVER - Google Patents

Abstract

THE PRESENT INVENTION RELATES TO A RADIO RECEIVER. ACCORDING TO THE INVENTION, IT INCLUDES A MEANS FOR ADJUSTING THE VOLUME 6 TO ADJUST THE VOLUME OF THE SIGNALS RECEIVED; A MEANS FOR GENERATING MOUTH SIGNALS, WHICH ARE APPLIED TO A TERMINAL 18, DURING THE TUNING OPERATION OF THE RADIO-RECEIVER; AND A TENSIONING VOLUME GENERATOR MEAN 20 FOR PRODUCING A TUNING VOLUME TO MAKE THE ATTENUATION OF THE VOLUME ADJUSTMENT MEANS MORE IMPORTANT AND THUS APPLY IT TO THE VOLUME ADJUSTMENT MEANS. THE INVENTION APPLIES IN PARTICULAR TO A MUFFLING MECHANISM FOR A RADIO-RECEIVER HAVING AN ELECTRONIC TUNING SYSTEM.

Description

The present invention relates to a radio receiver, and more

  particularly to improvements to a muting mechanism of a radio receiver of an electronic tuning system having an electronic volume control circuit in a low frequency amplifier. A conventional electronically tuned radio-receiver has been constructed as illustrated in FIG. 1. The reference 1 designates an antenna, the mark 2 a high frequency amplifier, the mark 3 a mixing circuit, the 4 mark an intermediate frequency amplifier reference 5 a low frequency amplifier, comprising an electronic volume control circuit 6 and a

  audio amplifier 7, and the mark 8 designates a loudspeaker

  speaker, respectively. Moreover, the reference 9 designates a loop circuit locked in phase to apply local oscillator signals for tuning, to the mixer circuit 3. The circuit 9 comprises a reference oscillator 10, a control circuit 11, a divider

  program 12, a phase comparator 13, a pass filter

  bottom 14 and an oscillator set to voltage 15.

  With this arrangement, in order to eliminate noises such as inter-service noises, the following mechanism has been proposed. As a result, a muting circuit 16 is provided before the low frequency amplifier 5 as can be seen in FIG. 2, and is operated

  to attenuate the audio signals of the internal amplifier

  4 when a muting signal is applied to a terminal 17 by the control circuit 11 during a

agreement operation.

  However, a muffling circuit as above causes a complication of the arrangement of the circuit. In particular, if there are a number of sources of audio signals, the circuit will be extremely complicated to cause an increase in its price.

of production.

  The present invention therefore relates to a radio-receiver o, by providing a control voltage generating voltage generator circuit for producing a voltage to control an electronic volume control circuit, the attenuation of this electronic volume control circuit. becomes more importantL when a signal

Muting is applied.

  According to the present invention, a radio

  receiver which comprises: volume adjusting means for adjusting the volume of the received signals; means for generating muting signals during a tuning operation of the radio receiver; and unaDyen tuning voltage generator for producing a tuning voltage to make the attenuation of the volume control means greater and thus apply it

by means of volume adjustment.

  The invention will be better understood and other purposes, features, details and advantages thereof

  will appear more clearly-during the description

  explanatory text which will follow with reference to the accompanying schematic drawings given solely by way of example illustrating several embodiments of the invention and in which: FIG. 1 gives a block diagram illustrating a structure of a tuned radio receiver; electronic; FIG. 2 gives a block diagram illustrating a traditional mechanism; Figures 3 and 5 each show a circuit diagram illustrating an embodiment of the present invention; and FIG. 4 is a graph showing the characteristic curve of the regulating voltage generator circuit, the adjustment voltage being indicated on the abscissa axis.

  and the attenuation on the y-axis.

  The present invention will now be described in detail with reference to preferred embodiments

  which are illustrated in the accompanying drawings.

  Fig. 3 shows a circuit diagram illustrating an embodiment of the present invention where the same reference marks and symbols used to designate circuits substantially similar to or identical to those of Figs. 1 and 2 are employed. The symbol Q designates a transistor, VR is the volume adjustment, 18 designates a mute signal input terminal, 19 designates an input terminal to which a reference voltage Vref is applied by the source 19 'of voltage reference, and the assembly forms a regulating voltage generator circuit 20. It is the adjustment or control circuit 11 which applies a muting signal to the

Terminal 18.

  The setting voltage generator circuit 20 produces a control voltage V which is then applied to the electronic volume control circuit 6. Thus, the attenuation of the volume control circuit can be

  adjusted by varying the adjustment voltage above.

  In addition, Figure 4 shows the characteristic curve

  of the regulating voltage generator circuit 20.

  In FIG. 3, when a muting signal is applied to the terminal 18, the transistor Q is turned on so as to emit a voltage of the order of OV.Thus, the adjustment voltage is of OV and consequently the attenuation of the electronic volume control circuit is controlled to be the largest, thereby creating

a condition of deafening.

  When no muting signal is applied, the reference voltage V can be set to a desired value between 0 and the reference voltage Vref by varying the volume VR. As a result, attenuation of the electronic circuit 6 of the volume control can

  also be set to a desired value.

  Figure 5 shows another embodiment of the invention. In this embodiment, resistors R1, R2 and R3 are provided in the regulation voltage generator circuit 20, as well as a delay circuit having a capacitor C1. With this arrangement, it is possible to slowly vary the reference voltage V

  generated by transistor Q when a deaf signal is

  is applied to terminal 18. Therefore, this allows the degree of muting to be adjusted with

  accuracy by the volume control circuit 6.

  As is apparent from reading the description

  In the foregoing, according to the invention, a voltage regulating voltage generator circuit is provided to adjust the attenuation of an electronic volumetric control circuit so that the greatest attenuation is obtained when a muting signal is applied and that it is possible to set the tuning voltage generating circuit to a desired attenuation value when no muting signal is applied. Consequently, the deafening operation can be performed with a structure

  simple circuit without the need for a

  as traditionally used. Indeed, the present invention has the advantages not only of reducing the production price but also of

  simplify the attenuation setting constant.

Claims (4)

  A radio receiver, characterized by comprising: volume adjusting means (6) for adjusting the volume of the received signals;   means (16) for generating deafness signals   during a tuning operation of said radio receiver, and tuning voltage generator means (20)   to produce a tuning voltage to make the tuning   volume adjustment means and   thus apply it to said volume adjustment means.   2. Radio receiver according to claim 1, characterized in that the aforementioned adjusting voltage generating means comprises at least one transistor (Q) which is connected to the aforesaid volume control means at one end and to the ground at the other, in order to become   in response to the muting signal.   3. Radio receiver according to claim 2, characterized in that the aforementioned adjusting voltage generating means further comprises a variable resistor (VR) and a reference voltage source (Vref) connected to said variable resistor, the voltage to the output of said variable resistor being applied by means of adjustment of the aforementioned volume.   4. Radio receiver according to claim 2, characterized in that it further comprises a delay circuit (C1) connected to the base of said transistor, the aforementioned deafening signal being applied to said   transistor by said delay circuit.