KR910004621Y1 - Luminance signal separating circuit of multi-system vtr - Google Patents

Abstract

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Description

Luminance Signal Separation Circuit of Multisystem VTI

1 is a circuit diagram of an embodiment of the present invention.

2 is a frequency characteristic diagram of an arm type and a Secam type high frequency filter.

3 is a frequency characteristic diagram of an arm type and a Secam type video signal.

* Explanation of symbols for main parts of the drawings

1: switching unit 2: discriminating unit

3: color processing part R ₁ -R ₃ : resistance

L ₁ -L ₃ : Coil C ₁ -C ₃ : Condenser

Q ₁ , Q ₂ : Transistor CP: Comparator

BF: Buffer NT: Inverter

According to the present invention, in the V-cam with dual-camera secam method, the tuning frequency of the high frequency filter separating the luminance signal and the color signal is different according to the recording and broadcasting method of the tape to be played back, and the high frequency filter having the different tuning frequency The present invention relates to a luminance signal separation circuit of a multi-system VTI that is automatically switched according to a broadcasting method used to accurately separate a luminance signal and a color signal.

Conventionally, in order to separate the luminance signal and the color signal, only one arm or sekam method high frequency filter is installed to be used in common for the arm and sekam method signals, so when using an arm high frequency filter (1.4MHZ) Color signal is generated on the screen by mixing the residual color signal with the luminance signal of the method, and when using the high-frequency filter (1.7MHZ) for the Secam method, there is a problem that the resolution of the arm method is decreased.

In order to solve this problem, the present invention discriminates whether the video signal picked up from the video head is recorded in the arm or secam method, and the high frequency filter and secam of the arm method are determined by the discrimination signal. As a high frequency filter of the scheme is designed to be selected automatically, the configuration and operation effects of the present invention will be described in detail by the accompanying drawings as follows.

Image signals picked up from the channel 1 image head HD ₁ and the channel 2 image head HD ₂ are applied to the reproduction amplifier PM through the selection switch SW and the shear amplifier PA ₁ PA ₂ , The output of the regenerative amplifier PM is applied to one input of the switching section 1, and is applied to the discriminating section 2 through the 630KHZ band filter PF and the color processing section 3, and this discriminating section 2 Is output to the other input of the switching section 1, and the output of the switching section 1 is applied to the automatic gain control circuit AGC through the reproduction equalizer PQ. .

In the above configuration, the switching unit 1 is a Secam method high frequency filter in which an image signal output from the reproduction amplifier PM is passed through a matching resistor R _{1 and} formed of a coil L ₁ and a capacitor C ₁ . And an armed high frequency filter of the coil (L ₂ ) and the condenser (C ₂ ) are applied to the collectors of the driving transistors Q ₁ and Q ₂ , respectively, while the transistors Q ₁ and Q ₂ The output (SH) (PH) of the discriminating unit (2) through the bias resistor (R _3- R ₆ ) is applied to the base, and the color signal that does not pass the high pass filter is condenser (C ₃ ), coil It is configured to be applied to the reproduction equalizer PQ via L ₃ and resistor R ₂ .

In the present invention configured as described above, the color signal of the arm method and the Secam method and the luminance signal recorded on the recording tape are the AM signal of the 629KHZ band which is 4.43MHZ low-converted, and the color signal of the Secam method is 4.40MHZ and This is a low frequency, 1.1MHZ band FM signal with 2 carriers of 4.25MHZ.

In the embodiment of FIG. 1 for example, the signal recorded in the recording Tate channel 1 and channel 2 heads (HD ₁₎ is picked up by a (HD _2), the front end amplifier via the pick-up video signal selection switch (SW) (PA ₁ ) (and is applied to the PA ₂₎ amplifying the primary at a predetermined level, the front end amplifier (PA _1), (the video signal the first amplified by the PA ₂₎ is applied to a normal playback amplifier (PM) section after the second amplification Through a resistor (R ₁ ) in the annulus ₁ , it is applied to a Palbar type high filter of coil (L ₁ ) and condenser (C ₁ ) and Secam type high filter of coil (L ₂ ) and condenser (C ₂ ), respectively. On the other hand, it is applied to the 630KHZ bandpass filter (PF), in this case, when the signal output from the reproduction amplifier (PM) is an arm type video signal, the arm type color signal from which the luminance signal is removed by the 630KHZ bandpass filter (PF) Is applied to the color processing unit 3 and converted into an original signal of 4.43 MHZ. When a converted color signal having a carrier of 4.43 KHZ is applied to the discriminating unit 2, the frequency-to-voltage converter FVC in the discriminating unit 2 converts the frequency of 4.43 MHZ to low voltage, and the peak voltage detector PD Detects the peak voltage and applies it to the non-inverting input terminal (+) of the comparator CP, to which the reference voltage Vr is applied to the inverting input terminal (-), and the output voltage of the comparator CP is at the 'high' level. As the 'high' level voltage is applied to the buffer BF and the inverter NT and inverted, the output PH of the discriminating unit 2 becomes a 'high' level voltage, and the output SH is When the low level is applied to the base of the driving transistor Q ₁ (Q ₂ ) through the bias resistors R ₃ -R _{6 in the} switching unit 1, the transistor Q ₁ is turned off. Transistor Q ₂ is conductive.

Accordingly, the 1.4 MHZ arm type high frequency filter having the same characteristics as that of the _{second A} of the coil L ₂ and the condenser C ₂ through the resistor R _{1 in the} switching unit 1 is output from the regenerative amplifier PM. Only 1.4MHZ luminance signal of the applied video signal flows to the transistor Q ₂ through the arm type high frequency filter, and the color signal that does not pass the arm type high frequency filter is condenser C ₃ and coil L _3. ) And a resistor (R ₂ ) are applied to a normal reproduction equalizer (PQ), and the output of this reproduction equalizer (PQ) is applied to a normal automatic gain control circuit (AGC).

In addition, when the signal output from the reproduction amplifier PM is a Secam type video signal, the output of the reproduction amplifier PM is a color output from the band filter PF when the image signal is applied to the 630KHZ band filter PF. There is almost no signal, and accordingly, the output of the color processing section 3 is almost absent so that the voltage applied to the non-inverting input terminal (+) of the comparator CP in the discriminating unit 2 is applied to the non-inverting input terminal (-). Since the output of the comparator CP becomes the 'low' level voltage by being lower than the applied reference voltage, the output SH of the discriminating unit 2 through the buffer BF and the inverter NT becomes the 'high' level voltage. And the output PH becomes a 'low' level voltage, and the output voltage of the driving transistor Q ₁ (Q ₂ ) is transmitted through the bias resistors R ₄ -R _{6 in the} switching unit 1. Transistor Q ₁ is applied to the base and transistor Q ₁ is turned on, and transistor Q ₂ is 'off' as the call of this transistor Q ₁ An image signal that is an output of a reproducing amplifier PM applied through a resistor R ₁ by operating a 1.7 MHZ Secam method high frequency filter having characteristics similar to those of the second stage of the coil L ₁ and the capacitor C ₁ connected to the selector. Among them, the Secam method luminance signal passes through the Secam method high frequency filter to the transistor Q ₁ , and the Secam method color signal which does not pass the Secam method high frequency filter is the condenser (C ₃ ), the coil (L ₃ ) and the resistance (P). ₂ ) to a normal reproduction equalizer (PQ).

As such, the present invention automatically selects an arm and secam method of high frequency filter which separates color and luminance signals according to the broadcasting method of the video signal reproduced by the head, and accurately separates the color signal for the corresponding broadcasting method. It is a useful design that improves the quality of the product by preventing the quality deterioration factor such as color bit generation or poor resolution.

Claims (1)

A band filter (PF) for inputting a video signal, which is an output of a normal reproduction amplifier (PM), to pass an arm type color signal, a color processing unit (3) for converting the output of the band filter (PF) to an FM original signal; Determination section 2 for judging whether the video signal inputted according to the output frequency of the color processing section 3 is an arm system or a secam system, and an arm system high range by the output (SH) PH of this determination unit 2. A luminance signal separation circuit of a multi-system VTI, characterized in that it comprises a switching unit (1) for selectively operating the filter and the Secam method.