JPH0712226B2 - Color video signal recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] Two color difference signals of a color video signal are line-sequentially recorded / reproduced, and the reproduced line-sequential color difference signal is again line homogenized and output. The present invention relates to a color video signal recording / reproducing device.

[Prior Art] With the current television standard system, the transmission of color vision image signals is performed by subcarriers (3.58MH
z) is modulated by two color difference signals and multiplexed with a luminance signal, that is, a transmission method using a so-called quadrature two-phase modulated signal is adopted.

However, since recording / reproducing a television signal is relatively easy to handle, the two color difference signals are once converted into so-called line-sequential signals that are alternately transmitted for each scanning line, and then recorded. / A method of reproducing may be used.

In this case, signal processing is performed such that the reproduced line-sequential color difference signal is restored to the original line homogenized signal.

FIG. 2 is a circuit system diagram showing a configuration of a conventional example of the above-mentioned device.

In the figure, 1 is an input terminal of the color difference signal RY, 2 is an input terminal of the color difference signal BY, 3, 4, 10, 11, 14 and 15 are clamp circuits, 5, 6, 12, 13, 16 and Reference numeral 17 is a switch circuit, 7 is a recording / reproducing unit, 8 is a line-sequential color difference signal, 9 is a line-sequential color difference signal delayed by 1H, and 18 is an output unit.

A conventional example will be described below with reference to the drawings.

First, at the time of recording, the two color difference signals RY and BY are
Input to input terminals 1 and 2. In order to remove unnecessary signals such as noise during the blanking period, the clamp circuits 3 and 4 clamp the respective signals, and then switch circuits 5 and 6 for setting the level during the blanking period.
And is sent to the recording / reproducing unit 7.

In the recording / reproducing unit 7, the reproduced line sequential color difference signal 8 and
The line-sequential color difference signal 9 delayed by one horizontal scanning period (1H) is output for line homogenization.

The line-sequential color difference signals 8 and 9 are clamped by the clamp circuits 10 and 11, respectively, and then switched by the switch circuits 12 and 13 to make the lines homogenized. The switch circuits 12 and 13 switch and output the color difference signal from the clamp circuit 10 and the 1H delayed color difference signal from the clamp circuit 11 for each horizontal scanning period. The switch circuit 12 outputs RY and the switch circuit 13 Outputs a BY signal.

The color difference signals RY and BY are respectively supplied to the clamp circuit 14
Switch circuits 16 and 17 after being clamped at and 15
Then, in order to remove the interference of the part other than the video signal period,
After setting the level in the blanking period, output section
It will be sent to 18.

[Problems to be Solved by the Invention] However, as can be seen from the description of the conventional example, 6 places of clamp circuits and 6 places of switch circuits are provided, and in the clamp circuit used for such a purpose, Inevitably, errors will occur due to variations in the potentials that are clamped to each other and differences in temperature characteristics. Therefore, as the number of clamp circuits increases, the error increases, and a temperature compensating circuit for compensating for the difference in temperature characteristics and the like are added, which is complicated.

Therefore, an object of the present invention is to increase errors due to variations in clamp potential and differences in temperature characteristics, and further to reduce the number of clamp circuits to a necessary minimum in order to simplify the temperature characteristics compensation circuit.

[Means for Solving Problems] In order to achieve such an object, a clamp circuit used during recording and a clamp circuit used during reproduction can be shared.

That is, a pair of clamp means for respectively clamping a pair of color difference signals, a first conversion means for making a pair of color difference signals line-sequential, a second conversion means for making a line-sequential color difference signal simultaneous, and a line-sequential color difference. A recording / reproducing means for recording / reproducing a signal, and at the time of recording, the line-sequential color difference signal which is clamped by the clamping means and obtained through the first converting means is recorded by the recording / reproducing means. During reproduction, the line-sequential color difference signal reproduced from the recording / reproducing means and the delayed line-sequential color difference signal are clamped by the pair of clamping means, respectively, and the clamped line-sequential color difference signal is divided into the second line It is characterized in that it is simultaneously output by the conversion means of.

[Operation] That is, according to the present invention, one clamp circuit is provided for each of the two color difference signals, and the blanking of the signal to be recorded is normalized and recorded. Since the reproduced line-sequential signal is line homogenized, it can be taken out as a line homogenized signal via the clamp circuit used during recording, and the signal blanking can be normalized and output.

[Examples] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit system diagram showing the configuration of an embodiment according to the present invention.

In FIG. 1, the same parts as those in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted. In the figure, 19, 20 are changeover switches, 21,
Reference numeral 22 is a changeover switch having three contacts a ₁ , a ₂ , a ₃ and b ₁ , b ₂ , b ₃ .

In the present embodiment, at the time of recording, the color difference signal RY from the input terminal 1 and the color difference signal BY from the input terminal 2 are selected by the changeover switches 19 and 20, and the crank circuits 3 and 4 are selected. Sent to each. Clap circuit 3,4
The RY and BY signals clamped at are blanked by the contacts a ₁ and a ₃ of the change-over switch 21 and the contacts b ₂ and b _{3 of the} change-over switch 22 for removing noise during the blanking period. Processing is performed.

Next, at the time of reproduction, the line sequential color difference signal 8 reproduced and output from the recording / reproducing unit 7 and the line sequential color difference signal 9 delayed by one horizontal scanning period are selected by the changeover switches 19 and 20, and the clamp circuit Sent to 3 and 4, respectively. The line-sequential signals clamped by the clamp circuits 3 and 4 are changed by the contact points a ₁ and a ₂ of the changeover switch 21 and the contact points b ₁ and b ₂ of the changeover switch 22 from the changeover switch 21 every one horizontal scanning period. The color difference signal BY is selected from the RY and the changeover switch 22 and sent to the output unit 18, and at the same time, the contact point a _{3 of} the changeover switch 21 and the changeover switch during the retrace line period.
The process of setting the level in the blanking period is performed by the contact b _{3 of} 21.

EFFECTS OF THE INVENTION As is apparent from the above, according to the present invention, the signal processing when line-sequentially recording and reproducing the color difference signal of the video signal is performed by providing only one clamp circuit for every two color difference signals. Can be performed with a simple configuration.

Further, since the number of clamp circuits can be reduced to the required minimum number, it is possible to reduce the error due to the deviation of the reference potential and the difference of the temperature characteristics. Further, the circuit for temperature characteristic compensation can also be simplified.

[Brief description of drawings]

FIG. 1 is a circuit system diagram showing a configuration of an embodiment according to the present invention, and FIG. 2 is a circuit system diagram showing a configuration of a conventional example. 1,2 …… Color difference signal input terminal, 3,4,10,11,14,15 …… Clamp circuit, 5,6,12,13,16,17 …… Switch circuit, 7 …… Recording / playback section, 8 …… Line-sequential color difference signal, 9 …… Line-sequential color difference signal delayed by 1H, 18 …… Output section, 19,20 …… Changeover switch, 21,22 …… 3-contact changeover switch.

Claims (1)

[Claims] 1. A pair of clamp means for respectively clamping a pair of color difference signals, a first conversion means for line-sequentializing a pair of color difference signals, and a second conversion means for synchronizing line-sequential color difference signals. A recording / reproducing means for recording and reproducing the line-sequential color difference signal, and at the time of recording, the line-sequential color difference signal clamped by the clamp means and obtained through the first converting means is the recording / reproducing means. When recording and reproducing, the line-sequential color difference signal reproduced from the recording / reproducing means and the delayed line-sequential color difference signal are respectively clamped by the pair of clamping means, and the clamped line-sequential color difference signals are A color video signal recording / reproducing apparatus, wherein the color image signal is reproduced simultaneously by the second converting means.