JPH0630430A - Television receiver and color contour part correcting circuit - Google Patents

Abstract

PURPOSE:To reduce a phase deviation between a luminance signal and a contour-corrected chrominance signal by switching the delay quantity of the luminance signal by an input signal. CONSTITUTION:A color contour signal in an inputted chrominance signal is detected through a difference circuit 4, a full wave rectifier circuit 5 and a comparator 6. The detection signal of the color contour signal is varied by a monostable multivibrator 7 in accordance with an input signal and a chrominance signal corrected at its color contour is outputted from a sampling and holding circuit 8. On the other hand, the delay quantity of the luminance signal is switched by a switch 3 in accordance with the input signal to match the phase of the luminance signal with that of the chrominance signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color signal contour enhancement circuit for a color television receiver. In particular, the edge portion is detected from both the color signal and the luminance signal to emphasize the contour of the color signal.

[0002]

2. Description of the Related Art The contour enhancement of a color signal is performed by detecting the contour portion (edge portion) of the color signal and making the change in the color signal of this portion steep.

For detecting the edge portion of the color signal, there is an indirect method for detecting the edge portion of the luminance signal associated with the color signal as disclosed in Japanese Patent Laid-Open No. 62-130092 (H04N9 / 68). JP-A-4-35595 (H04N9 / 68) discloses a direct method for detecting an edge portion from a color signal.

A color contour correction circuit by the latter direct method will be described with reference to FIGS. 3 and 4.

The input color signal (31) is further differentiated through a differentiating circuit (4) and a full wave rectifying circuit (5),
A pulse (33) for changing the amplitude of the color signal is generated through the comparator (6). While the pulse is HIGH, the input color signal is sampled and held by the sampling and holding circuit (8). Hold the level and output the input color signal as it is during the LOW period.
The contour portion of the color signal can be emphasized like the waveform of (35).

Then, in order to match the phases of the luminance signal and the corrected color signal, it is necessary to delay the luminance signal by the delay circuit (9).
Since the TW length of 1 changes, the phases of the luminance signal and the color signal may not match.

Particularly, when the input signal is a VTR, the maximum frequency of the color signal is up to about 300 KHZ, whereas the color signal of the broadcasting group is 500 KHZ or more, and the phase greatly shifts with one delay amount. There is.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and it is an object of the present invention to change the delay amount of a luminance signal in accordance with an input signal to reduce the phase shift from a contour-corrected color signal. To aim.

[0009]

According to the present invention, there is provided a color signal contour detecting means for detecting an edge portion of a color signal and outputting a first color signal edge portion detecting signal, and the color signal contour detecting means. Second color signal edge part detection signal generating means for generating a second color signal edge part detection signal by varying the obtained first color signal edge part detection signal according to an input signal; and an input luminance signal. Delay means for delaying the color signal, a delay variable means for varying the delay amount of the delay means according to an input signal, and a color signal edge portion detection signal output by the second color signal edge portion detection signal generating means. According to the present invention, there is provided a color contour correction circuit comprising sample holding means for holding the color signal to enhance the contour of the color signal, and a television receiver including the color contour correction circuit. is there.

[0010]

According to the present invention, with the above-mentioned configuration, the phase shift between the luminance signal and the contour-corrected color signal due to the input signal is reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation of the present invention will be described below with reference to FIGS. Incidentally, the same drawing number as the conventional example operates in the same manner, and therefore its explanation is omitted.

In the present invention, a configuration different from the conventional one is that a second delay circuit (2) for delaying a luminance signal and a switch (3) for varying the delay amount are provided, and a color signal The point is that a monostable multivibrator (7) that changes the pulse of the contour detection signal and a control circuit (10) that controls the switch (3) and the monostable multivibrator (7) are provided.

Next, the operation will be described. First, the input color signal (11) passes through a differentiating circuit (4) and a full-wave rectifying circuit (5) and a comparator (6) to create a pulse (13) for the changing portion of the color signal amplitude. The monostable multivibrator (7) is synchronized with the rising edge of this pulse.
Gives a pulse (14) of constant width.

At this time, the control circuit (1
0) changes the time constant of the monostable multivibrator (7) to change the pulse width. This pulse (1
The color signal input during the period 4) is HIGH, the amplitude level immediately before that is held by the sampling and holding circuit (8), and the input color signal is output as it is during the period LOW (18). The contour portion of the color signal can be emphasized like the waveform of.

Changing the pulse width (14) in this way is as follows.
For example, the maximum frequency of the color signal of the VTR is about 300 KHZ, so the change in amplitude requires 1.7 μsec at the earliest.
Therefore, the pulse (14) having a constant width needs to be 1.7 μsec or more. On the other hand, since the maximum frequency of the broadcast wave color signal is up to 1.5 MHZ, the change in amplitude is 0.33 μsec. This is to prevent the possibility that the above amplitude change disappears.

Since the contour portion of the color signal is delayed by an appropriate constant width (14) according to the input signal as described above, it is necessary to delay the luminance signal (15) so as to match it. When delaying the luminance signal (15), it is necessary to delay 1.7 μsec in the case of VTR as described above, so the first delay circuit (1) + second delay circuit (2) = 1.7 μsec is set. To do.

On the other hand, in the case of broadcast waves, the color signal is, for example, 1M.
If the rise of HZ is made, the delay amount of the luminance signal (15) is 0.5 μsec, and in FIG. 1, the first delay circuit (1)
By having two delay lines so that the second delay circuit (2) = 1.2 μsec, the two input signals can be appropriately dealt with.

Therefore, the control circuit (1
The delay time can be varied by switching the switch (3) in 0).

Further, by increasing the time constant of the monostable multivibrator and the number of delay circuits, it is possible to increase the rising frequency of the chrominance signal by several times and more appropriately match the phases of the luminance signal and chrominance signal.

[0020]

According to the present invention, when performing color contour correction,
The chrominance signal and the luminance signal can be adjusted to appropriate phase states by the input signal.

[Brief description of drawings]

FIG. 1 is a drawing showing an embodiment of the present invention.

FIG. 2 is a waveform chart of each point in the embodiment of the present invention.

FIG. 3 shows a conventional circuit example.

FIG. 4 is a waveform diagram of each point in a conventional circuit example.

[Explanation of symbols]

 1 1st delay circuit 2 2nd delay circuit 3 switch 4 differentiator circuit 5 full wave rectifier circuit 6 comparator 7 monostable multivibrator 8 sample hold circuit 10 control circuit

Claims (2)

[Claims] 1. A color signal contour detection means for detecting an edge portion of a color signal and outputting a first color signal edge portion detection signal, and a first color signal edge obtained from the color signal contour detection means. Second color signal edge part detection signal generating means for generating a second color signal edge part detection signal by varying the part detection signal in accordance with the input signal; and delay means for delaying the input luminance signal. Holding the color signal by a delay variable means for varying the delay amount of the delay means in accordance with an input signal; and a color signal edge detection signal output from the second color signal edge detection signal generation means. And a color contour correction circuit including sample and hold means for enhancing the contour of the color signal. 2. A color signal contour detection means for detecting an edge portion of a color signal and outputting a first color signal edge portion detection signal, and a first color signal edge obtained from the color signal contour detection means. Second color signal edge part detection signal generating means for generating a second color signal edge part detection signal by varying the part detection signal in accordance with the input signal; and delay means for delaying the input luminance signal. Holding the color signal by a delay variable means for varying the delay amount of the delay means in accordance with an input signal; and a color signal edge detection signal output from the second color signal edge detection signal generation means. And a sample holding means for enhancing the contour of the color signal.
Characteristic contour correction circuit.