JPS5831151B2 - Television receiver display circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display circuit for a television receiver, and relates to a circuit for displaying a muted state with the volume at O and a state in which the volume is present on a color picture tube in different colors. The purpose is to provide

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

As shown in FIG. 1, the pulse width control type volume variable circuit 7 is controlled by the volume control signal applied from the terminal 12, and the output signal 11 of this circuit T is passed through the filter circuit 2 to control the volume control circuit 26. , the volume emitted from the speaker 27 can be adjusted.

On the other hand, a volume display control circuit 1 is provided in order to display a display bar of a constant width that extends and contracts in the horizontal direction below the picture tube 6 so that the volume level can be visually confirmed.

As an input to this circuit 1, a horizontal synchronizing signal is applied from a terminal 8, a vertical synchronizing signal is applied from a terminal 9, and a display control signal is applied from a terminal 10 to generate a sawtooth wave with a horizontal period. Compare the wave with the output of the filter circuit 2,
A signal obtained based on the vertical synchronization signal is formed into a signal to be displayed in a bar shape on a part of the picture tube, and the volume bar display drive circuit 4
The voltage is applied to the picture tube 6 via.

Note that this display is erased approximately 1 second after the volume adjustment operation is completed by the display control signal, so that the image is not made more difficult to see than necessary.

On the other hand, the output 11 of the channel 7 is also applied to the pulse presence/absence discrimination circuit 3, and when a pulse is present, that is, when there is even a slight sound, the volume bar display drive circuit 4 is operated and the muffle bar display drive circuit 5 is operated. First, a display bar of a certain color, for example green, is displayed.

The length of this display bar changes depending on the volume; it is long when the volume is high, and short when it is low.

When there is no pulse, that is, when there is no sound at all, the volume bar display drive circuit 4 is not operated and the muffling bar display drive circuit 5 is operated to display, for example, a red display bar over the entire width below the screen of the picture tube 6.

This red display bar is displayed continuously when the volume is O,
This is something that can visually convey the volume.

As shown in FIG. 2 atb, the pulse width of the output pulse 11 can be changed by the pulse width control type volume variable circuit 7 by the volume adjustment operation.
is applied via terminal 12.

Changed by the signal.

When the volume of the output pulse 11 is decreased, the falling part becomes 1.
As the volume changes from 3 to 14 to 15, the pulse width becomes narrower, and as the volume increases, the pulse width changes from 13 to 16 and becomes wider.

In this case, with the volume down switch, the pulse width can be narrowed to 15, but the pulse width cannot be narrowed further and 15 pulses remain.

Then, when the mute switch is pressed, the pulse 15 disappears and changes to O level 17, and the pulse disappears.

A transition to 0 level 17 can be made from any pulse width by pressing the mute switch, and this state is called a mute state.

To return to the original volume from muted mode, press the mute switch again.

The pulse width in the minimum volume state is narrow, and when this is smoothed by the filter circuit 2 in Figure 1, the voltage applied to the volume control circuit 26 is almost the same as when the pulse disappears, and no sound can be heard. be.

A mute switch is installed on the transmitter of the remote control device, and is used when you want to temporarily mute the sound if you receive a call or have a visitor while watching TV.

Various circuits can be considered as the pulse presence/absence determination circuit 3 that determines the presence or absence of a pulse.

As examples of this circuit, a peak detection circuit and a monostable circuit with improved discrimination ability are shown in FIGS. 3a and 3b and FIG. 5, and their operation is shown in FIGS. 4 and 6.

Figure 3a shows a peak detection circuit using a diode 19.
By setting a large charge/discharge time constant ratio, the voltage 24 required to drive the next stage can be reduced even for short pulse widths.
(Figure 4b).

A pulse 11 shown in FIG. 4a is applied through a resistor 18 to charge the capacitor 20 and turn on the transistor 21.
An output 23 is obtained from the emitter.

22 is an emitter resistor.

Figure 3 shows a peak detection circuit that utilizes the diode characteristics between the base and emitter of the transistor 25.
In the circuit of Figure a, the reverse impedance of the diode 19 and the emitter-follower circuit configuration increase the impedance of the base of the transistor 21,
This circuit prevents malfunctions caused by leakage from the power supply voltage.

Pulse 11 is applied via resistor 24 to the base of transistor 25 and output 23 is obtained from the emitter.

26 is an emitter resistor, and 27 is a capacitor.

The circuit shown in Fig. 5 is an example improved by a monostable circuit using transistors 31 and 32. Even if the pulse width of pulse 11 decreases, the pulse has a constant pulse width (-2 in Fig. 6). The system is designed to enhance the ability to determine the presence or absence of

A pulse 11 shown in FIG. 6a is applied as an input to the monostable circuit, and a wide pulse shown in FIG. is obtained.

An embodiment in which the circuits 3, 4, and 5 shown in FIG. 1 are replaced by the circuit shown in FIG. 3 is shown in FIG. 7.

The volume bar display drive circuit 4 and the muffling bar display drive circuit 5 are negative logic AND circuits using diodes and transistors, and the negative logic output is applied to the base of the drive transistor of the drive circuit via the diode. Ru.

The signal of the volume display control circuit 1 and the level of the integral output 23 of the pulse presence/absence discrimination circuit 3 are detected, and the pulse width modulation output pulse 11 disappears due to the operation of the mute switch, and the integral output becomes O■, and the circuit 1 At the timing when the signal from the signal becomes 0.sup., an AND is taken and the output 30 is added to the transistor 35 to be at a high level, and in addition to the cathode of R--Y of the picture tube 6, a red bar-shaped display indicates the muted state.

On the other hand, the volume bar display indicating the volume of the sound is obtained by ANDing the signal 28 obtained by inverting the signal 23 with the transistor 36 and the control signal from the circuit 1 when the pulse width modulation output pulse 11 is present, using the transistor 37. The output 29 is set to a high level and is added to the G-Y cathode of the picture tube, and the length of the green color is displayed according to the volume.

As described above, according to the present invention, the loudness of the sound can be displayed on the screen of the television receiver, and the length of the display bar can be changed in accordance with the change in the sound volume to make the sound volume visually appealing. It is extremely easy to operate.

Furthermore, when the sound is muted using the mute switch, it can be displayed in a different color from the display bar that displays the volume, so it is obvious that the mute switch is being used.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a display circuit of a television receiver according to an embodiment of the present invention, FIGS. 2a and 2b are operational waveform diagrams of the same circuit, and FIGS. 3a and b, and 5 are diagrams of the same circuit. Circuit diagrams of main parts, Fig. 4a, b, Fig. 6a. b and c are operational waveform diagrams of the same circuit, and FIG. 7 is a circuit diagram of the main part of the same circuit. 1...Volume display control circuit, 3...Pulse presence/absence determination circuit, 4...Volume bar display drive circuit, 5...Muffling bar display drive circuit, 6...
... Picture tube, 7 ... Pulse width control type volume variable circuit, 26 ... Volume control circuit, 27 ...
・Speaker.

Claims (1)

[Claims] 1 A volume control circuit that controls the volume of the sound emitted from the speaker, a pulse width control type volume variable circuit that controls this volume control circuit, and synchronization with a signal based on the output of the pulse width control type volume variable circuit. a volume display control circuit that generates a signal to display the volume on the screen of the picture tube based on a symbol; a pulse presence/absence determination circuit that determines whether or not there is an output from the pulse width control type volume variable circuit; A volume bar display drive circuit applies the output of the volume display control circuit to the picture tube according to the output of the discrimination circuit, and displays the volume in the first color; 1. A display circuit for a television receiver, comprising: a mute rod display drive circuit that applies the output of the volume display control circuit to a picture tube and displays mute in a second color.