JPH0614715B2 - Switching sound elimination circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for canceling switching noise generated at the time of switching in a switch switching circuit used for a television receiver or the like.

2. Description of the Related Art Conventionally, a switching sound erasing circuit as shown in FIG. 3 has been used for a switching circuit used in a television receiver or the like.

In FIG. 3, reference numerals 21, 22, 23 and 24 are current limiting resistors, 25 and 26 are changeover switches, and 27, 28, 29 and 3 are shown.
Reference numeral 0 is a trigger pulse coupling capacitor, 31 is a delay circuit using a monostable multivibrator, 32 is a switching transistor, and 33 is a volume control terminal. 34 and 35 are control terminals controlled by the changeover switches 25 and 26.

In the circuit connected as described above, the changeover switch 2
5 is an interlocking two-circuit switch, one switch is
The fixed contact g is connected to the power source through the current limiting resistor 21,
The fixed contact i is grounded. The movable contact h is connected to the control terminal 34 to control the voltage, and also applies a trigger pulse to the delay circuit 31 by the monostable multivibrator via the coupling capacitor 27. Since the delay circuit 31 using the monostable multivibrator operates with the falling pulse shown in FIG. 4F, the changeover switch 25 is fixed to the fixed contact i.
When it is switched to, the rising pulse shown in FIG. Therefore, in the other switch of the interlocking two-circuit switch, the fixed contact j corresponding to the fixed contact g is grounded to the ground, and the fixed ground 1 corresponding to the fixed contact i is connected to the power source through the current limiting resistor 22. It is connected to the monostable multivibrator 31 via the coupling capacitor 28 as shown in FIG.
Give the falling pulse of. As a result, the monostable multivibrator 3 can be used regardless of whether the changeover switch 25 is closed to the fixed contact g or j or fixed contact i or 1.
1 is configured to be supplied with a trigger pulse.

Next, the monostable multivibrator 31 delays the switching noise generated in the transient state at the time of switching to the time required to eliminate the switching noise, and gives a pulse having the pulse width shown in FIG. 4G to the base of the switching transistor 32. As a result, the switching transistor 32 is turned on and the sound volume control element 33 is grounded, so that the sound volume is reduced to the minimum level and the sound is muted. The volume control terminal 33 at this time is the fourth
The operation of FIG. H is performed. The same operation is performed for the changeover switch 26.

The potentials of "H" and "L" appearing at the control terminal 33 are for switching stereo / monaural in the reception of audio multiplex broadcasting, while the potentials of "H" and "L" appearing at the control terminal 34 are. Is for switching the main audio and the sub audio when receiving the same broadcast.

Problems to be Solved by the Invention However, in the above configuration, the control terminals 34, 3
No. 5 has a problem that it is limited to voltage control. Further, when a changeover switch is further added, the number of parts for erasing the changeover sound increases and the circuit becomes complicated and a large area on the printed circuit board is required. There is a problem. In view of the above problems, the present invention is to provide a switching sound erasing circuit having a configuration in which a control target is not limited to voltage control and can be freely selected, and which can be easily dealt with even when a changeover switch is added.

Means for Solving the Problems In the switching sound erasing circuit of the present invention, one switch forming an interlocking two-circuit switch is inserted between a power source and a ground via a resistor, and a connection point between the switch and the resistor is connected. The control voltage is obtained and this control voltage is added to the switching sound cancellation signal generation circuit for generating the switching sound cancellation signal so that the switching sound cancellation signal is obtained from the output end of this circuit, and the other switch is configured to output a plurality of signals. It is characterized in that it is configured to function as a control switch for switching and outputting a signal from the source.

The switching sound erasing circuit of the present invention is configured such that one of the two circuit switches functions independently as a switching sound erasing switch and the other functions as a control switch, so that the controlled object can be freely selected, Moreover, even if the changeover switch is added, only the changeover switch to be added may be connected in series, and it is possible to easily cope with it without increasing the number of other parts.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1, 2 and 3 are current limiting resistors.
Reference numerals 4 and 5 are changeover switches, and 6 is a trigger pulse coupling capacitor. Reference numeral 7 is a delay circuit using a monostable multivibrator. Reference numeral 8 is a bypass diode, which together with the delay circuit 7 constitutes a switching sound elimination signal generating circuit. 9 is a switching transistor. 10 is a volume control terminal,
Reference numerals 11 and 12 are control terminals controlled by the changeover switches 4 and 5. Reference numerals 13 and 14 denote signal source terminals. For example, the signal source terminal 13 is applied with the main audio signal at the time of receiving the audio multiplex broadcast, and the signal source terminal 14 is applied with the sub audio signal.

In the circuit configured as described above, the changeover switch 4
Is an interlocking two-circuit switch, and the fixed contacts d and f are connected to the power source via the current limiting resistor 2. The movable contact e is connected to the fixed contacts d and f of the changeover switch 5. The movable contact e of the changeover switch 5 is grounded. That is,
The changeover switches 4 and 5 are set so as to be connected in series with one of the changeover sound erasing switches. The fixed contacts d and f of the changeover switch 4 generate the pulse shown in FIG. 2A only while the switch at the moment when any of the changeover switches 4 and 5 is changed is not closed to either of the fixed contacts d and f. It is a condition that the changeover switch used here is non-shorting (a switch in which the movable contact at the moment of changeover is in an open state without being closed by any fixed contact).

The pulse of FIG. 2A is given to the monostable multivibrator 7 as a trigger pulse via the coupling capacitor 6,
Here, the pulse shown in FIG. 2B is applied to the base of the switching transistor 9 with a delay until the time required to eliminate the switching noise generated in the transient state at the time of switching.

Here, since the monostable multivibrator 7 operates at the falling edge of the pulse A, the pulse shown in FIG. 2A is given to the base of the switching transistor 9 by the bypass diode 8 as it is, and the pulse from the monostable multivibrator 7 is supplied. When superimposed on B, the pulse shown in FIG. 4C is obtained. As a result, the switching transistor 9 is rendered conductive by the pulse C and the sound volume control terminal 10 is grounded, so that the sound volume is reduced to the minimum level and the sound is muted. The volume control terminal 10 at this time operates as shown in FIG. 2D.

The other switch of the changeover switch 4 has a fixed contact a connected to the power source through the current control resistor 1 and a fixed contact C connected to the ground. The movable contact b is connected to the control terminal 11 and an example of performing voltage control on the control terminal 11 is shown. For example, with the changeover switch 4, between a and b,
By selectively short-circuiting between b and c, the control terminal 11
It is possible to obtain a voltage of "H" or "L", and it is possible to switch between stereo / monaural at the time of receiving the audio multiplex broadcast. On the other hand, the switching sound erasing signal generating circuit can also be driven. The other switch of the changeover switch 5 functions as a control switch, and the fixed contact a is connected to the signal source terminal 13 and the fixed contact c is connected to the signal source terminal 14. The movable contact b is connected to the control terminal 12, and the changeover switch 5 causes the signal S1 of the signal source terminal 13 to be transmitted.
Alternatively, either the signal S2 from the signal source terminal 14 is applied to the control terminal 1
2 shows an example in which the switching is performed in order to act on 2.
For example, if the signal S1 applied to the signal source terminal 13 is the main audio signal at the time of audio multiplex broadcast reception and the signal S2 applied to the signal source terminal 14 is the sub audio signal, the signal itself can be directly switched without voltage control. Becomes

In addition to the above, the control switch side operates independently of the switching sound erasing switch side, so that the control target can be freely selected.

Further, when the changeover switch is added, it can be dealt with by connecting switches for erasing the changeover sound in series and without increasing the coupling capacitor.

EFFECTS OF THE INVENTION As described above, according to the present invention, the control system is limited to the voltage control as in the related art by operating the interlocking two-circuit switch independently of the control switch and the switch sound erasing switch. It becomes possible to choose freely.

Furthermore, by connecting the changeover switch in series between the power supply and ground, the changeover sound elimination circuit can easily cope with the expansion of the changeover switch simply by connecting the changeover switches in series. There is a great one.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a switching sound erasing circuit in an embodiment of the present invention, FIG. 2 is a time chart showing the operation of the circuit,
FIG. 3 is a circuit diagram of a conventional switching sound erasing circuit, and FIG. 4 is a time chart showing the operation of the circuit. 1, 2, 3 ... Current limiting resistance, 4, 5 ... Changeover switch, 6 ... Trigger pulse coupling capacitor, 7 ... Delay circuit by monostable multivibrator, 8 ... Bypass diode, 9 ... Switching transistor, 10 ……
Volume control terminals, 11, 12 ... Control terminals, 13, 14 ...
… Signal source terminal.

Claims (3)

[Claims] 1. An interlocking two-circuit switch and a switching sound erasing signal generating circuit, wherein one switching sound erasing switch forming the interlocking two-circuit switch is inserted between a power supply line and a ground via a resistor. Then, a control voltage is obtained from the connection point of the switch and the resistor, the control voltage is added to the switching sound elimination signal generating circuit to obtain the switching sound elimination signal from the output terminal, and the other switch has a plurality of A switching sound erasing circuit configured to function as a control switch that switches and outputs a signal from a signal source. 2. The switching sound erasing circuit according to claim 1, comprising two interlocking two-circuit switches, one of the switching sound erasing switches being connected in series with each other. 3. A switching sound erasing switch for a first interlocking two-circuit switch, wherein two fixed contacts are commonly connected and connected to a power supply line via a resistor, and a common contact is switched between the second interlocking two-circuit switch. Connect to the two fixed contacts of the sound erasing switch, connect the common contact of the second interlocking two-circuit switch to ground, and switch the connection between the two fixed contacts of the first interlocking two-circuit switch and the resistor The switching sound erasing circuit according to claim 2, which is connected to the signal generating circuit.