JPS6171794A - Color mark insertion circuit of video signal reproducing device - Google Patents

Abstract

PURPOSE:To simplify and scale down the circuit constitution and to obtain a stable hue color mark by constituting such that a chrominance subcarrier as a reference chroma signal is outputted to a chrominance signal transfer circuit from a phase locked loop circuit. CONSTITUTION:An extraction circuit 7 of a color burst is constituted of a horizontal synchronizing signal separator circuit 10, a burst gate pulse generator circuit 11, a color burst signal detection circuit 12 and a sample hold pulse generator circuit 13. A phase locked loop circuit 8 has a function for outputting a color burst phase error signal from an output terminal 14 synchronous to a color burst signal, and is generally constituted of a sample and hold circuit 16, an integration circuit 17 and a voltage control-type crystal oscillator circuit 18.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a video system in which a color symbol signal is superimposed on a reproduced video signal so that color symbols can be inserted and displayed in a reproduced image based only on the reproduced video signal. This invention relates to a color symbol insertion circuit for a signal reproducing device.

BACKGROUND OF THE INVENTION Conventionally, video signal reproducing apparatuses have been known that are capable of displaying characters, numbers, figures, and other symbols in a reproduced image by inserting them in color as color symbols. This video signal reproducing device has a color symbol insertion circuit, and the color symbol insertion circuit includes a color signal phase shifter to which a hue control signal is input for giving color information to a symbol signal having luminance information. and a symbol insertion circuit that superimposes a color symbol signal to which color information is added based on the color signal phase shift circuit on a reproduced video signal.

By the way, the color signal phase shift circuit of the conventional color symbol insertion circuit is a variable delay circuit that delays the color subcarrier having a frequency of 3.58 MHz by a predetermined phase and outputs it. It consists of a voltage-controlled all-pass filter that amplitude modulates the color subcarrier output from the variable delay circuit.
The hue control signal changes the delay amount of the variable delay circuit to change the phase of the color subcarrier, and the voltage-controlled all-pass filter modulates the amplitude of the color subcarrier that has undergone thousand-way modulation. However, conventional color symbol insertion circuits generally have complex and large circuit configurations, and require stable color tones including five hues and saturation. It has a problem that it is difficult to obtain a color signal with .

Purpose of the Invention The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to simplify and downsize the two-circuit configuration, and to obtain a color symbol with a stable color tone. An object of the present invention is to provide a color symbol insertion circuit for a video signal reproducing device.

The present invention was made by focusing on a phase-locked loop circuit that outputs a phase error signal to color burst 1 in synchronization with a color burst signal included in a reproduced video signal. The feature is that the color subcarrier such as a reference chroma signal is outputted from the face-locked loop circuit to the color signal transfer circuit, and the color subcarrier is input to the color signal transfer circuit. A hue control signal is input to each of the two input terminals, and the phase of the color subcarrier is controlled by the hue controller 1 to 1.
A resonant circuit that outputs a chroma signal as color information by changing it with a roll signal, a phase inversion circuit that inverts the phase of the chroma signal output from the resonant circuit, and a hue control circuit that inputs the roll signal and outputs the chroma signal as color information. It consists of a switch circuit that switches the chroma signal output from the resonant circuit between a chroma signal whose phase is inverted and a chroma signal whose phase is not inverted.

According to this device, a phase-locked loop circuit outputs a color subcarrier as a reference chroma signal toward a resonant circuit in synchronization with a colorverse 1 signal. When the hue control signal is input, the resonant circuit phase-modulates the color subcarrier based on the hue control signal and outputs it to the phase inversion circuit. At this time, the switch circuit functions to switch the chroma signal output from the resonant circuit between a chroma signal whose phase is inverted by the hue control signal and a chroma signal whose phase is not inverted. Therefore, it is possible to selectively designate a plurality of hues and supply color symbol signals to the symbol signal insertion circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a color symbol insertion circuit for a video signal reproducing apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a main circuit of a video signal reproducing apparatus according to the present invention. In FIG. The circuit 2 and the impedance conversion circuit 3 are connected to each other, and a symbol signal insertion circuit 4 is provided between the video signal amplification circuit 2 and the impedance conversion circuit 3. The reproduced video signal is supplied to a video signal amplification circuit 2 via an input terminal 5, and a symbol signal insertion circuit 4. It undergoes predetermined processing by the impedance conversion circuit 3 and is supplied to the output terminal 6 as a television signal.The reproduced video signal here includes color verse 1-1 in the back porch portion of the horizontal synchronization signal.
Signals are provided. In FIG. 1, reference numeral 7 indicates an extraction circuit for this color burst signal. This color burst signal extraction circuit 7 constitutes a color burst phase error detection system together with a face-locked loop circuit, which will be described later. Reference numeral 7 is composed of a horizontal synchronizing signal dividing circuit 10, a burst 1-1 pulse generating circuit 11, a color burst signal detecting circuit 12, etc., a sample-hold pulse generating circuit 13, etc. The horizontal synchronizing signal dividing circuit 10 has a function of outputting a detection pulse to the burst gate pulse generating circuit 11 and the sample hold pulse generating circuit 13 based on the horizontal synchronizing signal. It has a function of generating a gate pulse toward the color burst signal detection circuit 12 based on the input of the detection pulse, and the sample hold pulse generation circuit 13 generates a gate pulse toward the sample hold circuit described later based on the input of the detection pulse. Colorverse 1
- The signal detection circuit 12 has a function of detecting a color burst signal based on the input of the gate pulse and outputting only this color burst signal to the face-locked loop circuit 8.

The phase-locked loop circuit 8 outputs a color burst phase error signal to an output terminal 17 in synchronization with the color burst signal.
It has a function of outputting from 1, and is roughly composed of a phase comparison circuit 15, etc., a sample hold circuit 16, an integrating circuit 17, etc., and a voltage-controlled crystal oscillation circuit 18.
9 is the crystal 9 of the voltage controlled crystal oscillation circuit 18! , showing a pendulum.

The phase comparison circuit 15 receives the colorverse I signal as well as the oscillation output of the voltage-controlled crystal oscillation circuit 18, and the phase comparison circuit 15 has a function of outputting the difference to the sample and hold circuit 16. The sample and hold circuit 16 stores the difference as colorverse 1-
It has a function of outputting it to the output terminal 14 as a phase error signal and also outputting it to the integrating circuit 17.
has a function of integrating the phase error signal to the color verse 1 output from the sample hole 1-circuit 16 and outputting it to the voltage-controlled crystal oscillation circuit 18. , the oscillation frequency is controlled based on the integrated voltage output from the integrating circuit 17. This voltage controlled crystal oscillation circuit 18
The oscillation frequency of the chroma signal fluctuates in the vicinity including 11.58 MHz, and its oscillation output is input to the color signal phase shift circuit 20 as a reference chroma signal, and the phase-locked loop circuit 8 The phase circuit 20 forms part of a color symbol insertion circuit.

The color signal phase shift circuit 20 includes a resonance circuit 21, a phase inversion circuit 22, and a switch circuit 23, as shown in FIGS. 2 and 3.
FIG. 2 shows an equivalent circuit of the color signal phase shift circuit shown in FIG. 3. A color subcarrier as a reference chroma signal is inputted to the resonance circuit 21 via an input terminal 24, and a hue control signal is inputted to the resonance circuit 21 via an input terminal 25. It has the function of changing the phase of the color subcarrier and outputting it as a chroma signal such as color information, and the phase inversion circuit 22 reverses the phase of the chroma signal by 180 degrees. The switch circuit 23 converts the chroma signal output from the resonant circuit 21 into a phase-inverted chroma signal and a phase-inverted chroma signal in response to a hue control 1 to roll signal input manually through the input terminal 26. It has a function to switch between the chroma signal and the chroma signal that is not used. The switch circuit 23 has a function of outputting this color subcarrier through an output terminal 27 toward an addition circuit 28, and the addition circuit 28 receives a symbol signal having luminance information input through an input terminal 29. The symbol signal insertion circuit 4 adds the color information and the color information and outputs the result to the symbol signal insertion circuit 4, and the symbol signal insertion circuit 4 reproduces the symbol signal to which the color information has been added and the color symbol signal is reproduced. It has a function to superimpose on

As shown in FIG. 3, the resonant circuit 21 includes a parallel circuit consisting of a coil 30 and a capacitor 31, a series circuit consisting of a resistor 32 and a capacitor 33, a Swiss-chute transistor 34, a resistor 35, etc. The resistor 35 and the parallel circuit constitute a basic resonant circuit.
The resonant frequency of the basic resonant circuit is set to 3.58 MHz. The color subcarrier is transferred to the 1-transistor 3 forming part of the phase inversion circuit 22 via this basic resonance circuit.
This is input to the base of No. 6. The switching transistor 34 is turned on when the hue control I-roll signal is input to its base via the input terminal 25.
The collector of switching 1 to transistor 34 is resistor 3
2 and one end of the capacitor 33,
Its emitter is grounded, the other end of the resistor 32 is connected to a line 37 having a potential of +Vcc, the other end of the capacitor 33 is connected to the base of a 1-transistor 36, and the capacitor 33 is When the switching 1 transistor 34 is turned on, its one end is grounded and incorporated into a part of the basic resonance circuit, and the resistor 32 is affected by the power supply voltage +Vcc when the capacitor 33 is incorporated into the basic resonance circuit. The resistance value is set to a large value so that it does not occur.

The resonant angular frequency ω1 of the basic resonant circuit is ω1=□・・・・・・(D CGI bottom What is required?

The phase φ1(ω) of the color subcarrier input to the base of the transistor 36 is obtained as follows.

Here, Ll is the inductance of the coil 30, C1 is the capacitance of the capacitor 31, and R1 is the resistance 1 of the resistor 35.
Directly, ω indicates the angular frequency of the color subcarrier, and ω = 2π
It is determined by fc...■.

However, fc is the color subcarrier carrier frequency 3.58MH
It is z.

When the capacitance of the capacitor 33 is incorporated into the basic resonant circuit, the resonant angular frequency ω2 of the basic resonant circuit is: °′"[]Umako°=-, q.

The phase φ2(ω) of the color subcarrier input to the base of the switching transistor 36 is determined by the following formula.

Here, C2 is the capacitance of the capacitor 33.

Therefore, the phase of the color subcarrier can be changed by turning on and off the switching transistor 34 according to the hue control signal. Here, when the capacitor 33 is incorporated in the basic resonant circuit and when it is not installed, the phase difference φ1 (ω) of the color subcarrier inputted to the base of the transistor 36 is set to 90°. ,
The values of the coil 30 and capacitors 31 and 33 are set.

Note that the amplitudes Gx(ω) and G2(ω) of the color subcarriers input to the base of the 1-transistor 36 are determined by the basic resonant circuit when the capacitor 33 is not incorporated in the basic resonant circuit. When the capacitor 33 is incorporated in the capacitor 33, it is obtained as follows.

Therefore, by appropriately selecting the resistor 35, the amplitude Gx(ω) of the color subcarrier input to the base of the transistor 36 when the capacitor 33 is not incorporated in the basic resonance circuit can be adjusted. When the capacitor 33 is installed, the amplitude G, :(ω) of the color subcarrier input to the base of the transistor 36 can be made equal to the amplitude G, :(ω) of the color subcarrier input through the input terminal 25. - Amplitude changes due to roll signals can be removed.

In addition, by appropriately selecting the resistance value of the resistor 32, the amplitude G1(ω
) can also be set to be equal to the amplitude G1 and the amplitude GJ(ω).

The 1-run transistor 36 has an amplification function, and here, the degree of amplification is set to OdB, which will be described later. The collector of the 1-transistor 36 is connected to the line 37 via a resistor 38 and partially connected to a transistor 110 via a capacitor 39, and the emitter of the 1-transistor 36 is connected via a resistor 38 to a transistor 110. It is connected to a line 42 having a potential of -Vcc and to the base of the 1-transistor 4.1 via a capacitor 43. The collectors of transistor 40°.14 are both connected to line 37, and transistor 4
Both 0.44 emitters are connected to the ground line 46 via a resistor 45 and directly to the output terminal 27. The base of the transistor 40 is connected to the collectors of the switching 1 to transistor 47, the line 37 via a resistor 48, and the ground line 46 via a resistor 49. It is connected to the line 37 via a resistor 50 and to the ground line 46 via a resistor 51.

Switching 1-transistor 47 is a transistor (1
It has the function of turning on and off the signals 0, 1I and 11, and a hue control signal is inputted to its base via an input terminal 26, and its emitter is grounded. Switching 1 - transistor 47 is
It functions as a switch circuit 23, and the input terminal 26
It turns on when the hue control 1-roll signal is input through the 1-transistor 10.
-When the transistor 47 is off, it is in an active state, and the 1-transistor 40 functions as an emitter follower of the chroma signal, and when the switching transistor 47 is on, the 1-transistor 40 is in a cut-off state. The 1-ran transistor 44 is in a cut-off state when the switching transistor 47 is off, and is in an active state when the switching transistor 47 is on, thereby functioning as an emitter follower of the chroma signal. According to this phase shift circuit 20, the phase of the chroma signal can be adjusted by ±90° or ±180° with respect to the phase of the reference chroma signal.
.degree. can be changed, so four types of colors can be set as color information.

Note that if the resistance value of the parallel resistance made up of the resistors 38, 48, and 49 is set equal to the resistance value of the parallel resistance made up of the resistors 41, 50.51, the output of the transistor 36 can be set to OdB.

Although the embodiments have been described above, the oscillation waveform of the reference chroma signal output from the voltage-controlled crystal oscillation circuit can also be a rectangular wave.

As explained above, the present invention provides a method for detecting a color subfield as a reference chroma signal from a face-locked loop circuit that outputs a color burst phase error signal in synchronization with a color burst signal included in a reproduced video signal. The face-locked loop circuit is configured such that the carrier wave is output to the color signal phase shift circuit, and the color signal phase shift circuit is configured such that the color subcarrier and the hue control signal are input, A resonant circuit changes the phase of the color subcarrier and outputs a chroma signal as color information, a phase circuit inverts the phase of the chroma signal output from the resonant circuit, and a hue control signal is input. Therefore, we decided to utilize a phase-locked loop circuit that consists of a switch circuit that switches between the chroma signal output from the resonant circuit and the chroma signal that is not phase-inverted, and outputs a color burst phase error signal. Simplification of the configuration of the signal phase shift circuit.

It has the effect of being able to be made smaller, and
By using a resonant circuit to output the chroma signal, the phase and amplitude of the chroma signal can be output as constant, making it possible to obtain a signal with stable color tone. be effective.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the main part configuration of a video signal reproducing device according to the present invention, FIG. 2 is an equivalent circuit diagram of a color shift and sum circuit of the video signal reproducing device according to the present invention, and FIG. FIG. 2 is a detailed circuit diagram of a color shift and sum circuit of the video signal reproducing device according to the present invention. 4... Symbol (n number insertion circuit, 8... Phase locked loop circuit, 20... Color transfer circuit, 21... Resonant circuit, 22... Phase inversion circuit, 23... Switch circuit.

Claims (1)

[Scope of Claims] A color signal phase shift circuit into which a hue control signal for giving color information to a symbol signal having luminance information is input;
and a symbol signal insertion circuit for superimposing a color symbol signal in which color information is added to a symbol signal having luminance information based on the color signal phase shift circuit on a reproduced video signal. an insertion circuit, which outputs a color burst phase error signal in synchronization with a color burst signal included in the reproduced video signal from a phase-locked loop circuit that outputs a color subcarrier as a reference chroma signal to the color signal phase shift circuit; The phase-locked loop circuit is configured such that the color signal phase shift circuit is configured such that the color subcarrier is input and the hue control signal is input, and the color signal phase shift circuit is configured such that the color subcarrier is inputted and the hue control signal is inputted, and a resonant circuit that changes the chroma signal according to the hue control signal and outputs a chroma signal as color information; a phase inversion circuit that inverts the phase of the chroma signal output from the resonant circuit; A color symbol insertion circuit for a video signal reproducing device, comprising: a switch circuit for switching a chroma signal output from the resonant circuit between a chroma signal whose phase is inverted and a chroma signal whose phase is not inverted.