JPS5918763Y2 - Muting device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to muting devices such as television receivers, and is particularly intended to eliminate audio noise when switching channels in a receiver equipped with a detent tuner that performs a tuning operation. purpose.

Conventionally, several proposals have been made to eliminate noise emitted from a speaker in a television receiver when a tuner contact passes through an empty channel during channel selection.

For example, Utility Model Publication No. 39-11812 is a typical example, and includes a changeover switch that is linked to a tuner and has one end connected to the audio input side, and a selection switch that can be preset for each station between the changeover switch and ground. It was a device in which the selection switch corresponding to a channel that is not being broadcast (empty channel) was preset in advance by being closed, and the audio input side was grounded to suppress noise when passing through an empty channel when selecting a channel.

However, all of these methods mute the audio circuit when the channel is empty, and are effective against noise such as clicking noise when switching from one receiving channel to another, or when contacts are separated or connected. It had no effect.

The present invention provides a muting device that can control noise so as not to be emitted from a speaker, especially when changing a tuner's channel selection.

An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram of main parts of a television receiver including a muting device of the present invention.

1 is a channel switching knob, 2 is a tuner, 3 is an IF section that converts the frequency of the RF output of the tuner, 4 is an audio demodulation section, 5 is a low frequency amplification section, and audio output is obtained from 6 speakers.

7 is a switch that is repeatedly turned on and off in conjunction with the rotation of the tuner by the mechanism shown in FIG. 2, 8 is a base resistor, 9 is a base connected to the switch 7 via the base resistor 8, and the emitter side is a low frequency amplification section. A transistor whose collector side is connected to the ground is connected to the input terminal 10 of the switch 7.
When is off, this transistor 9 is set to be off.

Figure 2 shows the main parts of the tuner 2 mechanism.
12 is a detent gear coupled to the tuner rotation shaft 11; 13 is a leaf spring whose one end is fixed to the case of the tuner 2 by a fixture 14; 15 is the leaf spring. The detent roller is pressed by the elastic force of a leaf spring 13 to the detent gear 12 attached to the detent gear 13.

The tip 16 of the leaf spring 13 is in contact with a lever 17 of a switch 7 attached to the case of the tuner 2.

In FIG. 2, it is assumed that the lever 17 is always elastically pressed downward by a spring built into the switch 7.

To explain the operation of this embodiment, while receiving a certain station, the tent roller 15 falls into the valley of the tent gear 12, the tip 16 of the leaf spring 13 is at the lowest position, and the switch 7 is turned off.

Therefore, since the transistor 9 is off, the sound is normally output from the speaker 6.

Next, when the channel switching knob 1 is rotated and closed in an attempt to switch channels, the detent gear 12 connected to the tuner rotating shaft 11 starts rotating, and the detent roller 15 starts to climb the mountain of the detent gear 12.

At this time, the tip 16 of the leaf spring 13 rises, and the switch 7
Push up the lever 17 to turn on the switch 7.

The output of this switch 7 reaches the base via the base resistor 8, the transistor is turned on, the input terminal 10 of the low frequency amplifying section 5 is grounded, and the audio output from the speaker 6 is muted.

In the above embodiment, when switching the tuner from one channel to the next channel, when the rotary shaft 11 of the tuner 2 begins to rotate, the switch 7 grounds the audio signal from the point at which the tip 16 of the leaf spring 13 rises slightly. Therefore, the noise generated when the contacts in the tuner are disconnected or connected is muted.

Therefore, if this embodiment is used together with the already known empty channel muting means, it is possible to create an extremely comfortable channel selection device in which no click noise or noise when there is no signal is emitted from the speakers. be.

Further, according to the present invention, the detent roller 15 is provided at the middle part of the leaf spring 13, one end of the leaf spring 13 is fixed to the fixture 14, and the tip part 16 is connected to the lever 17 of the switch 7.
, the plate spring 13 functions with the fixture 14 as the fulcrum, the detent roller 15 as the point of effort, and the tip 16 as the point of action, so the difference between the peaks and troughs of the detent gear 12 is minute. Moreover, even if the stroke of the lever 17 is large, even such a switch can be turned on and off sufficiently by this lever action.

In other words, the switch 7 can be turned on and off by a slight movement of the detent roller 12 from trough to trough or from trough to trough, and the audio signal can always be grounded before the tuner moves, making it always stable. You can perform various actions.

In the above embodiment, the transistor 9 is turned on when the switch 7 is turned on, but the circuit is not limited to this, and the input terminal 10 of the low frequency amplifying section 5 is grounded by the output of the switch 7. Anything is fine.

It goes without saying that any detent type tuner can be used regardless of whether it is for VHF or UHF.

As described above, the muting device of the present invention is an excellent device that can reliably and stably eliminate noise when switching channels and allows comfortable channel selection.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the main parts of a television receiver equipped with an embodiment of the present invention, and FIG. 2 is a sectional view of the main parts showing the mechanism of this embodiment.

Claims (1)

[Scope of utility model registration request] a detent gear coupled to the rotation shaft of the tuner; a leaf spring having a contact portion that moves up and down along the detent gear and elastically presses the contact portion against the detent gear; A detent-type tuning tuner performs a tuning operation when rotating; a switch that contacts one end of the leaf spring and is turned on and off according to the vertical movement of the leaf spring; and a part of the audio circuit that outputs audio from the switch. a sound control means for suppressing output, the other end of the leaf spring being fixed, and the abutting part being provided between the one end and the other end of the leaf spring.