JPS61167280A - Control circuit for velocity-modulating circuit in a television receiver - Google Patents

Abstract

PURPOSE:To effect contour compensation by the operation of a velocity- modulating circuit by the control signal YS indicating the absence of the input external BCG signal when the external video signal is introduced to an external video terminal of a group of RGB input terminals. CONSTITUTION:An RGB connector 1 has an input for control signals YS for switching RGB input, external video input, audio input and IGB signal from the internal signal to outer signals. When a TV/RGB button 2 is set to RGB, a speed modulating VM circuit 11 is turned off by switches SW4, 8 and 13. However, a signal YS is detected by a control circuit 14, a control output is outputted to a VM switch to turn the circuit 11 on and off so that the circuit 11 operates when monitoring the video external output of the RGB mode. Since the RGB signal is issued when the signal YS is '1', the circuit 11 is turned off, while it is turned on when the signal YS is '0' to produce high quality images with compensated contour.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a control circuit for a speed modulation circuit in a television receiver, and is particularly applicable to a television receiver equipped with an RGB signal input mode. be.

[Conventional technology]

Television receivers are known that have an image contour correction function using speed modulation. This receiver is equipped with an auxiliary deflection coil for velocity modulation, and a velocity modulation circuit (VMH path) modifies the edge corresponding to the image contour of the video signal into an appropriate waveform and applies it to the auxiliary deflection coil to form the image contour. It is configured to correct.

Apart from this, a television receiver is known that is equipped with an RGB signal input terminal in addition to an RF input terminal (antenna input terminal). When monitoring external RGB signals, speed modulation cannot be applied because there is no video signal (luminance signal). For this reason, for example, RF/RGB (or TV
/RGB), a switch linked to the input selector switch is provided to turn off the speed modulation circuit.

The external RGB signal is an EIA called RGB connector.
It is supplied from the outside via a J standard 21-pin multi-connector. This RGB connector also includes an external video input terminal, making it possible to monitor an external video signal or even a composite color video signal. In this case, if you set the receiver to RGB monitor mode, the speed modulation function will disappear as described above, so the RGB
When monitoring the above-mentioned external video signal in the monitor mode, the speed modulation function cannot be used, so there is a problem that higher quality images cannot be obtained.

[Problem that the invention seeks to solve]

In view of the above-mentioned problems, the present invention provides a method that allows velocity modulation to be applied in the same way as the RF high-input internal video signal even in RGB monitor mode, so that high image quality with contour correction can be obtained. purpose.

[Means for solving problems]

The present invention provides video signals within the receiver and RGB input from the outside.
Switching operation means for switching and monitoring signals (T in the embodiment)
V/RGB button 2) and the input terminal for the control signal Ys for switching the RGB signal from the internal signal to the external signal (
RGB signal input terminal group (RGB connector 1
) and a circuit (VM circuit 11) that performs speed modulation for image contour correction based on a video signal, the control circuit for a speed modulation circuit in a television receiver.
- A control circuit is provided that manually inputs the control signal Y and a mode signal formed by operating the switching operation means, and the mode signal is an external RGB mode, and the control signal Y is an input of an external RGB signal. When this occurs, the speed modulation circuit is rendered inoperable.

[Effect]

If the RGB signal input terminal group is equipped with an external video input terminal, the control signal y indicates that no external RGB signal is input when this external video is input, so the speed modulation circuit is operated at this time. .

〔Example〕

FIG. 1 is a circuit diagram of a main part of a television receiver equipped with a control circuit for a speed modulation circuit according to the present invention.

The RGB connector 1 in Figure 1 is ErAJ standard TTC-0.
03r Television receiver and peripheral equipment interconnection J
(January 1983), and is equipped with an RGB input, an external video input, an audio input, and a Y signal input, which will be described later.

This television receiver is equipped with a TV/RGB button 2 which is a switch button between RF large input RGB, and when it is set to the TV side, the RF
The output of the TV (video) circuit 3 that processes large inputs is applied to the Y delay circuit 5 and the color extraction band pass filter 6 through the changeover switch 4 linked to the button 2, and the respective outputs are
The C processing circuit 7 processes the RGB outputs (3-wire output), and converts these RGB outputs into TV, , -' R(-+
It is linked to the +3 button 2, and the 1゛■ side of the selector switch 8 is pressed #
It is led out from the output circuit 9 to CRTIO. - The brightness output of the force and Y delay circuit 5 is the speed modulation circuit i1
(VMH path), the velocity modulation coil 12 (VMH path) is processed.
coil) to perform contour correction.

When TV/ROB button 2 is set to RGB side, selector switch 4
．． 8 becomes the RGB side, and an RGB mode is entered in which the RGB signal from the RGB terminal 1a of the RGB connector 1 and/or the external video signal from the external video terminal 1b is monitored.

In this case, three types of monitors are possible: RGB input only, external video input only, and RGB input superimposed on external video input (superimposed).

In the case of RGB input alone, the changeover switch 13 provided before the aforementioned changeover switch 8 is switched from the main line side to the RGB side, and the ROB input is connected to these changeover switches 13.
．． 8 via a video output circuit 9 directly to the CRTIO. This changeover switch 13 is coupled to the RGB side by the Y of the RGB connector 1 and the high level "1" Y signal from the signal terminal IC.

This Ys signal is a control signal for switching the RGB signal to an internal signal and an external signal, and according to the EIAJ standard, it is "1" when it is an external signal and "0" when it is an internal signal.
It becomes.

In the case of external video input alone, there is no RGB signal, so the Y5 signal is 0'', the changeover switch 13 is on the internal side (main line side), and the changeover switches 4 and 8 are on the TV/
RGB button 2 is on the TRGB side, so RG
The video signal from the external video terminal 1b of the B connector 1 can be monitored instead of the internal video signal.

When in the superimposition mode of external video input and RGB input, each selector switch 4, 8.13 is in the above-mentioned external video input only mode, and while the external video input is monitored, the RGB input signal portion is Y, the signal changes from "0" to "1" and the RGB input is selected by the changeover switch 13. Therefore, an external video screen on which RGB images such as characters are superimposed is obtained.

As mentioned above, the VM circuit 11
When the 602 is set to the RGB side, it is turned off by a switch, but so that the VM circuit 11 works even when monitoring external video input in RGB mode, it detects the Y signal and turns off the RGB signal when it is 1". Since the signal is out, V
When the M circuit 11 is turned off and the Y signal is "0",
The VM circuit 11 is turned on.

In this way, the control circuit 14 in FIG.
The switching state of the /RGB button is discriminated and a control output is output to the VM switch 15 to turn the VM circuit 11 on and off.

The control circuit 14 is configured as shown in FIG.
B inputs "0") and generates a "1" output (VM off) or a "0" output (VM on).

In the TV mode (at the time of RF input), a mode signal "1" obtained by the TV/RGB button 2 is applied to the NOR circuit 22 to force its output to "O", thereby turning on the VM circuit 11.

In RGB mode, only when the Ys multiplied signal becomes 1'' (at RGB input), this is detected by the Y signal detection circuit 20, and the output is held for several fields in the hold circuit 21 before being output as a 0'' signal. is given to the NOR circuit 22 as TV
Coupled with the /RGB mode signal "O", the output of the NOR circuit 22 is set to "1", thereby turning off the VM circuit 11. Therefore, speed modulation is not performed when only RGB input is received.

When using an external video monitor in RGB mode, select Y,
Since the signal is 0", the output of the hold circuit 21 is "
1', the output of the NOR circuit 22 becomes "0", so VM
Modulation is performed on the monitor image of the external video input.

Here, when superimposing characters etc. based on RGB signals on the monitor image of the external video, the Ys times signal becomes "1" only in this character part and the external video/
RGB switching occurs. This Y.

Since the signal is held for several fields in the hold circuit 21, the VM circuit 11 is turned off for the entire superimposed screen. Therefore, even if the Y signal turns on and off at a high frequency within one screen on which external RGB images are superimposed, the VM circuit 11 will not follow this and turn on and off, so speed modulation No interference occurs.

Note that when there are no more RGB signals to be superimposed, the VMH path 11 starts operating after several fields.

Figure 3 shows the specific circuit shown in Figure 2, with Y at transistor T1.
Detect the s-times signal and use the next stage capacitor CI.

C2 and transistor T2. Integral hold is performed at T3, and the next stage transistor T4. A NOR circuit 22, which matches the collectors of T5, performs a NOR operation with the mode signal of TV/RGB to obtain the switch output of the VM circuit 11 from the switch transistor T6.

In addition, the TV/RGB mode signal is set to TV=”0”, R
If it is set as GB-1'', the output of the hold circuit 21 is set to 1'' at ys-“l”, and the switch output “1” for turning off the VM can be obtained by AND logic. In addition to this, various logical configurations can be implemented.

〔Effect of the invention〕

As described above, the present invention refers to the control signal Y included in the external RGB input terminal group (RGB connector 1), and when the external RGB mode is selected, the signal Y, ? The receiver's speed modulation circuit is configured to turn off only when the presence of GB input is indicated, so even in RGB mode, the speed modulation circuit is turned on for external video input and contour correction is performed. High quality images can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a main part of a 1'I''L/V receiver to which the present invention is applied, Fig. 21M+ is a block diagram of the control circuit shown in Fig. 1, and Fig. 3 is a specific diagram of the control circuit shown in Fig. 2. There is a circuit diagram S. In the symbols used in the drawing,
・−・−−−−−−−−−・−RGB input terminal 1 b
----------1. External video input terminal 1 cm.--1.--Y, signal input terminal 2.
---------TV/RG B button 10-----
-----1・---CRTl 1------1・---
-1--V M circuit 12-------1・-----V
M coil 14--------Control circuit 15----- VM switch 20-
---------------Y, signal detection circuit 21-----Hold circuit 2
2---------m-----NOR circuit.

Claims (1)

[Claims] A switching operation means for switching and monitoring the video signal inside the receiver and the RGB signal from the outside, and a control signal Y_ for switching the RGB signal from the internal signal to the external signal.
In the television receiver, the television receiver is equipped with a group of RGB signal input terminals including input terminals of s, and a circuit that performs speed modulation for image contour correction based on the video signal.
_s and a mode signal formed by the operation of the switching operation means are provided as inputs, and when the mode signal indicates the external RGB mode and the control signal Y_s indicates the input of the external RGB signal, A control circuit for a speed modulation circuit in a television receiver that disables the speed modulation circuit.