JPH0352058Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a color television receiver.
More specifically, the present invention relates to a blanking processing circuit that processes blanking pulses for blanking a screen.

BACKGROUND ART FIG. 1 is a block diagram of a circuit included in a video circuit of a conventional color television receiver. Integrated circuit A is contrast circuit A
1. It has a DC (direct current) regeneration/bright circuit A2 and a blanking circuit A3. The contrast circuit A1 adjusts the contrast of the image of the cathode ray tube B using a variable resistor R1. The DC reproduction/bright circuit A2 adjusts the brightness of the image of the cathode ray tube B using a variable resistor R2.
Blanking circuit A3 receives the horizontal and vertical synchronization pulses and generates blanking pulses for blanking the image. transistor
T _r 1 to T _r 3 drive the cathode ray tube B, each collector of which is connected to the cathode of the cathode ray tube B.

FIG. 2 is a block diagram showing a configuration in which a color signal input interface circuit 2 is further inserted into a conventional general color television receiver similar to that shown in FIG. The contrast circuit 21 to which the video signal is supplied is a circuit that adjusts the contrast of the image of the cathode ray tube B using a variable resistor R21, and its output signal is sent to a DC (direct current) reproducing circuit 22.
is regenerated to DC level. The RGB level adjustment circuit 24 adjusts each level of a red color signal R, a green color signal G, and a blue color signal B from an external device such as a microcomputer using a variable resistor R24. The DC reproduction circuit 25 is the RGB level adjustment circuit 2
The DC level of the output signal from 4 is regenerated and made equal. The mixing/switching circuit 23 performs matrix operation on the color difference signal from the television receiver side and the luminance signal from the DC reproduction circuit 22, and connects the brightness circuit 26.
The color signals R, G, and B are given to . Furthermore, by switching, the mixing/switching circuit 23 supplies the color signal from the DC reproduction circuit 25 to the bright circuit 26, and superimposes it on the color signal from the television receiver. The bright circuit 26 adjusts the brightness of the image using a variable resistor R26, and its output signal is given to a blanking circuit 27.
The blanking circuit 27 receives the horizontal synchronizing pulse and the vertical synchronizing pulse, and supplies a blanking pulse for blanking the image to the video output circuit.

Such a circuit configuration causes the following problems. The video/color demodulation circuit shown in Fig. 2, which is equipped with input terminals for color signals R, G, and B from external equipment, cannot use the integrated circuit A with the configuration shown in Fig. 1 as is, so it is an integrated circuit. It is impossible to standardize the chassis on which A is mounted, and the chassis must be designed completely differently, resulting in a decrease in design efficiency and an increase in costs.

An object of the present invention is to provide a color television receiver that can use common parts, thereby reducing costs.

Structure of the invention The invention consists of a contrast circuit that receives a video signal and sets the contrast of the image, a bright circuit that sets the brightness of the image, and a blanking circuit that generates a blanking pulse that erases the blanking line of the image. a blanking pulse slice circuit F2 that slices the blanking pulse from the video circuit F1 near the black level of the video signal, and an output signal of the blanking pulse slice circuit F2 and an external circuit. A color signal of a color television receiver obtained by receiving a color signal from a device and performing DC reproduction by setting the level of the blanking pulse included in the output signal of the blanking pulse slice circuit F2 to a pseudo black level. and an RGB interface circuit 2a that switches and derives the color signal from the external device.

Embodiment FIG. 3 is a block diagram of an embodiment of the present invention. The integrated circuit F1 in which all the video/color demodulation circuits are integrated includes a contrast circuit 31, a DC reproduction/bright circuit 32, a blanking circuit 33, and a transistor 35. The contrast circuit 31 receives the video signal and connects the variable resistor R3.
1 to adjust the contrast of the image. The DC reproduction/bright circuit 32 is a contrast circuit 31
The brightness of the image is set in advance to a semi-fixed state using the voltage of the adjustment power supply 34. The blanking circuit 33 receives the horizontal synchronizing pulse and the vertical synchronizing pulse, and sends out a blanking pulse for blanking the scanning lines of the screen. The blanking pulse operates the transistor 35, and its emitter output is passed through the capacitor C1.
The signal is applied to the RGB interface circuit 2a.
The RGB interface circuit 2a has a configuration similar to that shown in FIG. 2 above. This circuit 2a is
From the video signal from the blanking pulse slice circuit F2 and the TV color difference signals R-Y, B-Y,
The switching circuit 4 performs DC reproduction and creates RGB color signals for the television receiver (sometimes abbreviated as television) by the matrix circuit 46.
Give to 7. In addition, the RGB color signal of the external device is
After DC reproduction, the signal is applied to the RGB switching circuit 47.
In this way, the color signal from the television and the color signal from the external device are switched and derived from the switching circuit 47.

Resistance R of blanking pulse slice circuit F2
33 is provided for normal operation of the video DC reproduction circuit in the circuit 2a. integrated circuit F
Regarding the output of 1, if blanking circuit 3
If the resistor R33 is not present as a result of the operation in step 3, the black level during the retrace period disappears as shown by the broken line in FIG. I end up not being able to do it anymore. Therefore, by adding the resistor R33, the peak of the waveform indicated by the broken line in FIG. , it becomes possible to operate approximately. Capacitor C1 is the video DC
This is for the integral time constant for operating the regeneration circuit. A resistor R32 is connected to the emitter of the transistor 35.
A voltage V is applied through the resistor R33, and its emitter is grounded through a resistor R33.

A video signal as shown in FIG. 4 is applied to the contrast circuit 31 of the integrated circuit F1. Resistor R33 connected to the emitter of transistor 35
If the blanking pulse P1 is not provided, a signal in which the blanking pulse P1 is superimposed on the video signal is sent out from the emitter of the transistor 35, as shown in FIG. In a typical conventional color television receiver, a signal from the emitter of the transistor 35 is applied to a video output circuit.

However, in this case, the voltage level of the signal sent from the emitter of the transistor 35 is higher than the normal value 2, so DC regeneration in the subsequent RGB interface circuit 2a is impossible. Therefore, a resistor R33 is provided between the emitter of transistor 35 and ground to lower the voltage level. With such a circuit configuration, the emitter output of the transistor 35 becomes a signal as shown by the solid line in FIG. 42. In FIG. 4, the level indicated by line 1 is the divided voltage of resistor R32 and resistor R33, and the level indicated by line 2 is the normal black level of the video signal of integrated circuit F1.

The constant ratio between the resistor R32 and the resistor R33 is determined by the relative relationship between the pedestal level of the video signal and the slice level of the synchronizing pulse, and creates a pseudo black level shown by line 1. Furthermore, resistance R3
2 and resistor R33.
It is necessary to fine-tune the pedestal level with respect to the slice level. To do this, the DC regeneration/bright circuit 32 shown in FIG. 3 is made semi-fixed, and the circuit constants for setting voltage etc. are adjusted during production. Capacitor C1 is connected to the DC level of integrated circuit F1.
Since it does not match with the RGB interface circuit 2a, the DC component is removed so that the integrated circuit F1 and the RGB interface circuit 2a can be easily connected. The RGB interface circuit 2a performs DC reproduction using the level shown by line 1 in FIG. 4 as a pseudo black level. The RGB interface circuit 2a generates blanking pulses and supplies them to the video output circuit by the operation described in FIG. 2 above.

As shown in Fig. 3, the integrated circuit F1 in which all the video/color demodulation circuits are integrated is used as it is,
It is configured so that the processed video signal is supplied to the RGB interface circuit 2, making it possible to share the chassis of the common line with general models. In this case, it is necessary to perform DC reproduction of the video signal again in the RGB interface circuit 2a, so video blanking should not be performed in the integrated circuit F1, but in order to simplify the general color television receiver. It is advantageous to process the blanking within the integrated circuit F1. Therefore, in the present invention, by connecting the blanking pulse slice circuit F2 between the integrated circuit F1 and the RGB interface circuit 2, blanking processing can be performed within the integrated circuit F1.

Effects As described above, according to the present invention, even when adding a color signal input interface circuit to the circuit of a conventional common color television receiver, connection can be easily made, reducing costs and It is possible to improve design efficiency by standardizing the chassis.

That is, according to the present invention, the video circuit F1, which is an integrated circuit including a contrast circuit, a bright circuit, and a blanking circuit, is further provided with a blanking pulse slice circuit F2, and its output signal is connected to a color signal from an external device. Based on this, the color signal on the TV side and the color signal on the external device side are switched and derived.
Therefore, even in color television receivers that do not require connection to external equipment, it is possible to share the video circuit F1, which is an integrated circuit, and to share the chassis equipped with the video circuit F1, which is an integrated circuit. Therefore, it is possible to reduce the number of parts and reduce costs.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a video circuit of a conventional general color television receiver, and Figure 2 is a block diagram of a configuration including a color signal RGB input interface circuit of a conventional general color television receiver. 3 is a block diagram of an embodiment of the present invention, and FIG. 4 is a waveform diagram for explaining the operation of the embodiment. 2...Interface circuit, 31...Contrast circuit, 32...DC regeneration/bright circuit, 3
3...Blanking circuit, 34...Adjusted power supply, R
31...Variable resistance, R32, R33...Resistance, C
1... Capacitor.

Claims (1)

[Claim for Utility Model Registration] A contrast circuit that receives a video signal and sets the contrast of the image, a bright circuit that sets the brightness of the image, and a blanking circuit that generates a blanking pulse that erases the blanking line of the image. a video circuit F1 which is an integrated circuit including; a blanking pulse slice circuit F2 that slices the blanking pulse from the video circuit F1 near the black level of the video signal; and an output signal of the blanking pulse slice circuit F2. The color of a color television receiver is obtained by receiving a color signal from an external device and performing DC reproduction by setting the level of the blanking pulse included in the output signal of the blanking pulse slice circuit F2 to a pseudo black level. 1. A color television receiver comprising: an RGB interface circuit 2a that switches and derives a signal and a color signal from the external device.