JPS607564Y2 - Tuning display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tuning display device suitable for use in a television audio receiver that receives television audio such as television audio multiplex broadcasting.

In a normal television receiver, if the local oscillation frequency fluctuates for some reason and the tuning goes out of tune, it is relatively easy to notice this out of tune by looking at the image on the screen. With a television audio receiver that does not have a standard TV receiver, it is difficult to notice the synchronization difference, and even when the sound quality is poor, I sometimes continue listening without realizing it.

For this reason, it was necessary to add a tuning display device to this type of television audio receiver.

Conventionally, a television audio receiver as shown in FIG. 1 has generally been used.

Here, 1 is an antenna, 2 is a tuner, 3 is an audio intermediate frequency amplification circuit, 4 is an FM detection circuit, 5 is an audio output amplification circuit,
Reference numeral 6 denotes a speaker, and after the audio signal detected by the FM detection circuit 4 is amplified by the amplifier circuit 5, television audio is emitted from the speaker 6.

Further, 7 is a level detection circuit, 8 is a tuning display output circuit, and 9 is a display device, and these constitute a tuning display device.Here, the level of the Oite intermediate frequency signal is level-detected in the level detection circuit 7, and the detected The output is supplied to a tuning display output circuit 8, and a display according to the output level is performed on a display device 9.

However, in the conventional tuned display device as described above, the television signal generally includes a video carrier wave, a video carrier wave, and an audio carrier wave.
Since a sub-picture carrier wave is included, there is a risk that the display device 9 may display a malfunction when detecting a sub-picture carrier wave or a sub-picture carrier wave between stations during a channel selection operation.

The present invention has been devised in view of these points, and it is an object of the present invention to provide a tuned display device that does not malfunction due to video carrier waves and sub-picture carrier waves in these television signals.

The present invention will be described below according to embodiments shown in the drawings.

FIG. 2 shows a block diagram of a television audio receiver using the tuned display device of the present invention, in which the same parts as in FIG. 1 are given the same reference numerals.

Reference numeral 10 denotes a well-known audio muting device attached to a television audio receiver, and the device 10 includes an audio amplification circuit 5', a mute drive circuit 11, a reference voltage circuit 12. AFC amplifier circuit 13, zero volt switch circuit 14
．． It is composed of an OR circuit 15, a mute control signal output circuit 16, and a mute control circuit 17.

In the above-mentioned muting device 10, especially when the television signal received by the antenna 1 is weak and the detection output of the level detection circuit 7 is extremely small, or when the detection output of the level detection circuit 7 is out of tune, the detection output signal of the level detection circuit 7 is or F
A mute control signal is generated based on the AFC signal obtained from the M detection circuit 4, and the mute control signal is supplied to the audio amplification circuit 5', and at this time, the amplification operation of the circuit 5' is stopped, and thus audio muting is performed. An action is taken.

On the other hand, when the received signal is relatively large and in tune, the muting device 10 does not generate a mute control signal, so the audio amplification circuit 5' performs a normal amplification operation, and the television audio is emitted from the speaker 6. be done.

In the present invention, the audio muting device 10 utilizes an audio mute control signal that is generated particularly when out of synchronization or when receiving a weak input signal, and stops the function of the tuning display output circuit 8 when the control signal is derived. In addition, in the present invention, fH (horizontal frequency signal) amplification circuit 18 and fH
, 4 detection circuits 19 are added, and the circuits 18 and 19 extract the fH power component contained in the intermediate frequency signal obtained from the level detection circuit 7, amplify and detect it, and in particular, fJ
, minutes are also detected, the function of the tuning display output circuit 8 is stopped.

That is, television signals, especially intermediate frequency signals, are generally
It has a frequency spectrum as shown in the figure, and includes a video carrier intermediate frequency signal fP' and a width video carrier intermediate frequency signal fc' in addition to audio carrier intermediate frequency signals f,'.

Among these, a video carrier wave fP' and a width video carrier f.

' components are all amplitude-modulated by the horizontal frequency fH.

On the other hand, the audio carrier wave b' is an FM signal and is not amplitude modulated.

Therefore, if a relatively large television signal is currently being received and is in a normal tuned state, and especially the audio carrier intermediate frequency signal fS' is extracted from the audio intermediate frequency amplification circuit 3, the level detection circuit 7 is outputting a detected signal. Since there is no fH command component, the detection output of the fH detection circuit 19 is not derived, and on the other hand, no mute control signal is derived from the muting device 10 either.

Therefore, at this time, the tuning display output circuit 8 is driven to output, and the display device 9 performs a tuning display operation.

However, even when the same tuning state is present, there is a slight deviation from the normal tuning state, and the audio intermediate frequency amplifier circuit outputs the video carrier intermediate frequency signal f2' instead of the audio carrier intermediate frequency signal f,'. When the fc' component is extracted and level-detected, the fH signal component contained therein fH amplification circuit 18 and f+-+ detection circuit 1
9, the fH detection circuit 1 is amplified and detected.
Tuning display output circuit 8 based on the detection output derived from 9.
operation is stopped.

Therefore, even if no mute control signal is derived in the audio muting device 10 at this time, no synchronization display operation is performed in the display device 9.

FIG. 4 shows a further embodiment of the tuned display device of the present invention.

Here, the mute control signal obtained from the mute control signal output circuit 16 of the audio muting device 10 is applied to the resistor R.
1 to the base of the tuning display output amplification transistor TR□, while the detection output signal of the level detection circuit 7 is supplied to the base of the fH amplification transistor TR2 via the coupling capacitor C□.

The emitter of the tuning display output amplifying transistor TR1 is directly grounded, and the collector is grounded via the tuning display light emitting diode D1 and connected to the positive atom B via a resistor R2.

Also, the emitter of the fH amplification transistor TR2 is a resistor R.
4, the base is connected to positive atom B through resistance B3, and the collector is connected to positive atom B through fH parallel resonant circuit consisting of filter L and capacitor C2, and fH It is connected to the base of the detection transistor TR3.

The emitter of the fH detection transistor TR3 is directly connected to the positive atom B, and the collector is grounded through a resistor R5 and connected to the positive atom B through a capacitor C3. and is connected to the base of the detection output amplification transistor TR4.

Further, the emitter of the transistor TR1 is directly grounded, and the collector is connected to the tuning display output amplifying transistor T.
Connected to the collector of R□.

When the received input signal is small at this moment or when the non-synchronized display state is present, the mute control signal output circuit 16
A mute control signal is derived from the transistor TR1, thereby making the transistor TR1 conductive, and a collector current flows through the transistor TR through the resistor R. At this time, the collector potential of the transistor TR1 is lowered, so that the light emitting diode D is turned on. Almost no current flows through the light emitting diode D.
□ is not emitted.

On the other hand, the mute control signal output circuit 16 is in the tuned state.
Even when a mute control signal is not derived from 1, the video carrier f,' component or the sub-picture carrier fc' component is output from the audio intermediate frequency amplification circuit 3 out of the normal tuning state, and the detected output of the level detection circuit 7. When the fH acid component is included, the AC component of the detection output is connected to the capacitor C.
It is supplied to the base of the fH amplification transistor TR2 through □.

At this time, at the collector of the transistor TR2, fHli
, are resonated in the resonant circuit of the capacitor C2 and the coil L□, and only the fH acid component is selectively taken out and applied to the base of the fH detection transistor TR3.

At this time, the transistor TR3 is made conductive, and a positive DC voltage is obtained at the collector as the f8 detection output by the action of the capacitor C3 and the resistor R5.

As a result, the output amplifying transistor TR4 becomes conductive, a collector current flows through the transistor TR4 via the resistor R2, and the collector potential of the transistor TR4 decreases.

Therefore, during this period, almost no current flows through the light emitting diode D1, and the light emitting diode D1 does not emit light.

However, when the audio carrier wave fs' component is output from the audio intermediate frequency amplification circuit in a normal tuned state, the detection output of the level detection circuit 7 does not contain the fH acid component, so the detection output amplification transistor TR4 is Since the tuning display output amplifying transistor TR□ is also in the cut-off state, current flows through the resistor R2 to the light emitting diode D, causing the light emitting diode D1 to emit light, and the normal It is displayed that the device is in synchronization state.

According to the tuning display device of the present invention, in a television audio receiver equipped with an audio muting device as described above, the fJ component is selectively detected and derived based on the intermediate frequency signal at the time of tuning, and the fH detection Since the tuning display operation is stopped based on the output and the mute control signal from the audio muting device, it is accurate only when the audio carrier wave is derived without malfunction due to the video carrier wave or sub-video carrier wave derived at the time of tuning. The display is synchronized with the

[Brief explanation of drawings]

FIG. 1 is a block diagram of a television audio receiver using a conventional tuning display device, FIG. 2 is a block diagram of a television audio receiver using a tuning display device according to the present invention, and FIG. 3 4 is a frequency spectrum of a television intermediate frequency signal, and FIG. 4 is a circuit configuration diagram of an embodiment of the tuned display device of the present invention. 3...Audio intermediate frequency amplification circuit, 7...
Level detection circuit, 8... Tuning display output circuit, 9
...display device, 10...audio muting device, 18...f, 4 amplifier circuit, 19.
... f8 detection circuit, TR□ ... tuning display output amplification transistor, TR2 ... f, 4 amplification transistor, TR3 ... fH detection transistor, TR4...Transistor for detection output amplification, D□...Light emitting diode for tuning display.

Claims (1)

[Scope of utility model registration request] In a television audio receiver equipped with an audio muting device, a tuning display output means including a tuning display element;
means for extracting a television audio intermediate frequency signal; and means for level detecting the intermediate frequency signal extracted from the means;
means for selectively extracting the horizontal frequency fH acid component from the detection output signal obtained from the means; means for detecting the f, J2;; detection output signal obtained from the fH detection means; and the audio muting. A tuning display device comprising means for controlling the display operation of the tuning display output means based on an audio mute control signal obtained from the device, and performing tuning display only when tuned to an audio carrier wave.