JPS598965B2 - Noise removal circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that performs switch control in response to the commercial power frequency voltage induced in the human body, particularly an electronic channel selection device that is used in television receivers and the like and has a noise removal circuit. Regarding.

An electronic channel selection device for a television receiver is generally constructed as shown in FIG.

When a human body comes into contact with any of the contact terminals T1, T2...Tn, usually by finger contact, the amplifier A, ~
Amplifier AI t corresponding to the contacted terminal in An
A corresponding one of the amplifiers A2 to Anx amplifies the commercial power frequency induced in the human body.

The amplified output is usually 50Hz or 60Hz and has a constant amplitude in a constant direction from the base level.

The corresponding memory part in the memory circuit 1 is set by the output, the tuning voltage distribution circuit 2 is controlled by the setting, the corresponding tuner 3 is tuned to the designated channel according to the output of the tuning voltage distribution circuit 2, and the image is received. A possible state is created.

In the above circuit, the input impedance of the amplifier must be kept fairly high.

However, when the input impedance is high, it is susceptible to noise other than the designated signal provided by finger contact.

Therefore, in the circuit shown in Figure 1, capacitors T1, T2...Tn are connected to each input terminal to generate noise, and most of the normal noise is impulse-like, containing frequency components much higher than the commercial frequency. , is removed.

Even if a capacitor corresponding to each channel is used in this way, it is powerless against noise generated inside the amplifiers A1 to An and after the input stage.

For example, it has no effect on noise related to power lines or shocking noise that occurs when the power is turned on.

SUMMARY OF THE INVENTION An object of the present invention is to provide a noise removal circuit for solving the above-mentioned problems in electronic contact switches.

Another object of the present invention is to facilitate the integration of electronic contact switches by using this noise canceling circuit.

In order to achieve the above object, the noise removal circuit according to the present invention connects the outputs of each amplifier through diodes.
A capacitor with one end grounded? It is connected to the other end of the parallel circuit of resistors.

With this configuration, the noise output generated in any amplifier, which contains many higher frequency components than the normal signal output, can be reliably removed, and integration is also facilitated. objective is fully achieved.

The noise removal circuit according to the present invention will be explained in more detail below with reference to the drawings.

FIG. 2 is a diagram showing an input portion of an electronic contact switch for a television receiver using a noise reduction circuit according to the present invention.

Amplifiers A1, A2...An are input terminals T1, T2, respectively.
...Tn, and output terminals 01, 0...On.

The anodes of diodes D, D2, .

The resistor 11 constitutes a load resistor for each amplifier or a part thereof.

The operating impedance of each diode D1, D2...Dn is made sufficiently low compared to the output impedance of the amplifier A1, A2...An and the resistor 11.

And it is usually quite easy to do so.

The capacitor 12 has a capacitance that exhibits a sufficiently low impedance against noise components.

Now, when a noise output above a certain level occurs in any amplifier, the corresponding diode becomes conductive, and the impulse noise is absorbed by the capacitor.

The effect on other amplifiers is blocked by the reverse characteristics of the diode.

Similarly, other amplifiers are not affected in any way even when signal output is occurring.

FIG. 3 is a diagram showing more specifically the relationship with the output side of the amplifier.

In FIG. 3A, transistor 21 represents the final output stage transistor of any amplifier.

The emitter of the transistor 21 is connected to a parallel circuit of a resistor 26 and a capacitor 27 via a diode 24.

Other amplifiers are similarly connected to resistor 26 and capacitor 27.

The noise output generated at the emitter of the transistor 21 is integrated and compressed by the output impedance and the capacitor 27.

As a result, the noise component does not activate the subsequent amplifier (or memory circuit) 25 whose input is the connection point between the resistors 22 and 23.

FIG. 3B shows yet another specific connection example.

Transistor 31 is the final output stage transistor of any amplifier.

In this example, the resistor 26 also serves as the collector load of the transistor 31.

The noise component is compressed by the action of the capacitor 27 and is not transmitted to the subsequent storage circuit 33 and the like.

As explained above, according to the noise removal circuit according to the present invention, noise components can be reliably removed with a simple circuit configuration.

In addition, since diodes are easy to integrate, capacitor 1
By attaching individual pieces externally, electronic contact switches and the like can be effectively integrated.

Although the configuration of the present invention has been explained in detail by showing specific examples, various modifications can be easily made.

For example, the polarity of the diode can be changed according to the polarity of the amplifier.

In short, the scope of the present invention is not limited to the specific examples described above, but extends to all of the scope of the claims.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the outline of an electronic channel selection device for a television receiver, and FIG. 2 is a diagram showing an example in which a noise removal circuit according to the present invention is applied to an electronic channel selection device for a television receiver. FIG. 3 is a diagram specifically showing the connection with the amplifier. T1, T2...Tn...Input terminal, Al j
A2...An...Amplifier, 01,02...
・On... Output terminal, 1... Memory circuit, 2... Tuning voltage distribution circuit, 3... Tuner, C1, C2... Cn. ... Capacitor, D,, D2"・D n t 24, 32" diode, 21, 31 ... Transistor, 11
, 22, 23, 26... Resistance.

Claims (1)

[Claims] 1 It has a plurality of contact terminals and a plurality of amplifiers provided corresponding to each contact terminal, and the electrical signal induced by the human body touching a predetermined contact terminal corresponds to the predetermined contact terminal. In an electronic tuning device that receives a predetermined broadcast station by amplifying it with an amplifier installed as 1. An electronic channel selection device comprising: a noise removal circuit having a noise absorption circuit; and an output signal to a next stage is obtained from a connection point between the amplifier and the diode.