JPS62272794A - Sequential scanning converter for color television signal - Google Patents

Abstract

PURPOSE:To enable the cost down of a device by Y/C separating a luminance signal and a carrier chrominance signal from an analog video signal, converting them into digital signals respectively, restoring them to analog signals after a sequence scanning conversion, demodulating three kinds of color difference signals from these chrominance signals and constituting an analog primary colors signal with these signals and the luminance signal. CONSTITUTION:After an analog luminance signal Y separated in a Y/C separation circuit 3 is converted into a digital luminance signal in an A/D conversion circuit 5a, it is sequentially scanned and converted in a sequential scanning conversion circuit 6a, converted into the analog luminance signal in a D/A conversion circuit 7a and supplied to addition circuit group 11a-11c. On the other hand, after an analog carrier chrominance signal C separated in the Y/C separation circuit 3 is converted into a digital carrier chrominance signal in an A/D conversion circuit 5b, it is sequentially scanned and converted in the sequential scanning conversion circuit 6a, converted into the analog carrier chrominance signal in a D/A conversion circuit 7b and then demodulated from the analog carrier chrominance signal which is completed to be sequentially scanned and converted to the color difference signal of primary colors in a color demodulation circuit 10 and supplied to addition circuit group 11a-11c. The addition circuit group 11a-11c constitutes the primary colors signals R, G and B and output them.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Purpose of the Invention Industrial Field of Application This invention relates to a progressive scan conversion device installed in a color television receiver, and in particular to a simple digital processing system. This invention relates to a progressive scan conversion device that is designed to be inexpensive by increasing the cost.

Conventional technology Recently, the analog video signal demodulated in a television receiver is first converted into a digital video signal, and then high-density display is achieved through sequential scan conversion using digital processing circuits that have become highly functional and inexpensive. Attempts have been made to improve the image quality of display screens by performing various image quality improvement processes such as noise removal, contour correction, etc., and then converting the signals back to analog video signals for display.

One such image quality improvement device is the progressive scan conversion word N.
(scan converter) doubles the line density in the field (line frequency 31.K
Hz) to improve image quality.

The above-mentioned progressive scan conversion device is constructed as shown in FIG.

That is, the analog three primary color signals supplied to the input terminal 21 are subjected to horizontal AFC, Y/C conversion, and color demodulation processing in the circuit 22, and from there, the three primary color color difference signals (R-Y), (G-Y ).

(B-Y) and a luminance signal Y are output. Each color difference signal and luminance signal are added in addition circuit groups 23a, 23b, and 23c, respectively, and the analog three primary color signals R, G, and B are added.
becomes. Each of these analog three primary color signals is passed through low-pass filter circuits 24a to 24c to the A/D conversion circuit 2.
5a to 25c, the signals are first converted into corresponding digital three primary color signals, sequentially scanned and converted in progressive scan conversion circuits 26a to 26c, and then converted into analog primary color signals that have undergone sequential scan conversion in D/A conversion circuits 2La to 27c. converted,
Output terminal 29a via low-pass filter circuits 28a to 28C
~29C are supplied to the subsequent display system.

Problems to be Solved by the Invention In the progressive scan conversion device shown in FIG. 2, the three primary color signals R1G,
Since a digital processing system consisting of an A/D conversion circuit, a sequential scanning conversion circuit, and a D/A conversion circuit is installed for each of the There is.

Structure of the Invention Means for Solving the Problems The progressive scan conversion device of the present invention which solves the problems of the prior art described above converts an analog color television signal passed through a horizontal AFC circuit into a luminance signal and a carrier color signal. After separating Y/C and converting each into a digital signal and performing sequential scan conversion processing, it is returned to the corresponding analog signal, and three types of color difference signals are demodulated from this analog carrier color signal that has undergone sequential scan conversion processing, By creating corresponding analog three primary color signals from each of these color difference signals and a luminance signal that has undergone sequential scan conversion processing, the digital processing system of the conventional device can be reduced to one.
It is configured to reduce the number of power systems and reduce the cost of equipment.

Hereinafter, the operation of the present invention will be explained in detail together with examples.

Embodiment FIG. 1 is a block diagram showing the configuration of a color television signal progressive scan conversion apparatus according to an embodiment of the present invention.

In the figure, 1 is an input terminal for a color television video signal to be subjected to progressive scan conversion processing, 2 is a horizontal AFC circuit, and 3 is a Y/C circuit.
Separation circuits, 5a and 5b are A/D conversion circuits, 6a and 6b are sequential scan conversion circuits, and 7a.

7b is a D/A conversion circuit, 8 is a low-pass filter circuit, 9 is a band-pass filter circuit, 10 is a color demodulation circuit, 11a, Ilb,
llc is an adder circuit, 12a, 12b.

12 c I=output terminal for three primary color signals subjected to sequential scan conversion processing.

An input terminal 1 is supplied with an analog video signal of an interlaced scanning system of a standard television system such as the NTSC system. If this analog video signal is reproduced from a recording medium such as a video tape recorder, line-by-line sick may occur due to mechanical fluctuations in the magnetic tape running system. This analog video color difference signal is passed through a Y/C separation circuit 3 through a horizontal AFC circuit 2 that performs phase locking based on the horizontal synchronization signal of each line to reduce the jitter.
supplied to

In the Y/C separation circuit 3, a luminance signal Y is extracted from a low-pass filter circuit 3a, and a carrier color signal C is extracted from a band-pass filter circuit 3b having a center frequency equal to the color subcarrier frequency.

The analog luminance signal Y extracted and separated by the Y/C separation circuit 3 is converted into a digital luminance signal by the A/D conversion circuit 5a, and then supplied to the sequential scan conversion circuit 6a. The progressive scan conversion circuit 6a performs a progressive scan conversion process that doubles the in-field line density of the luminance signal by inserting an interpolation line of the luminance signal created from the adjacent lines of the digital luminance signal of the interlaced scanning method. conduct. The digital luminance signal that has undergone the progressive scanning conversion process is converted into a corresponding analog luminance signal in the D/A conversion circuit 7a, and then passes through the low-pass filter circuit 8 to the adder circuit groups 11a to Ilc.
is supplied to the luminance signal input terminal of.

On the other hand, the analog carrier color signal C extracted and separated by the Y/C separation circuit 3 is converted into a digital carrier color signal by the A/D conversion circuit 5b, and then supplied to the sequential scan conversion circuit 6a. The progressive scan conversion circuit 6b doubles the in-field line density of the carrier color signal (line frequency 31 .5
K11z) is performed.

The digitally transported color signal, which has undergone progressive scan conversion, is
It is converted into a corresponding analog carrier chrominance signal in the A conversion circuit 7b, and is supplied to the chrominance demodulation circuit 10 via a bandpass filter circuit 9 having a center frequency equal to the chrominance subcarrier frequency.

The color demodulation circuit 10 generates color difference signals of three primary colors (R-Y), (G-
Y) and (B-y), and supply each to the color difference signal input terminals of the adder circuit groups 11a to 11c.

Adder circuit group 112 whose configuration is represented by adder circuit 11a
~IIC performs progressive scan conversion by adding the progressive scan converted color difference signal output from the color demodulation circuit 10 (7) and the progressive scan converted luminance signal output from the low-pass filter circuit 8. Create processed three primary color signals R, G, and B, and send them to output terminals 12a to 12.
Output to c.

Effects of the Invention As explained in detail above, the progressive scan conversion device of the present invention converts an analog video signal into a luminance signal and a carrier color signal in Y/
After converting each into a digital signal and performing sequential scan conversion processing, it is returned to the corresponding analog signal, and three types of color difference signals are demodulated from this analog carrier color signal that has undergone sequential scan conversion processing, and these color difference signals are Since the configuration is such that the corresponding analog three primary color signals are created from each signal and the luminance signal that has undergone sequential scan conversion processing, the number of digital processing systems can be reduced by one compared to conventional devices, making it possible to reduce the cost of the device.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the structure of a progressive scan converter according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the structure of a conventional progressive scan converter. 1...Input terminal, 2...Horizontal AFC circuit, 3...Y/C
Separation circuit, 5a, 5b...A/D conversion circuit, 5a, 5b
. . . Progressive scanning conversion circuit, 7a, 7b . . . D/A conversion circuit, 10 . . . Color demodulation circuit, 11a to IIC . . . Addition circuit. Patent applicant: NEC Home Electronics Co., Ltd.

Claims (1)

[Claims] The analog color television signal passed through the horizontal AFC circuit is Y/C separated into a luminance signal and a carrier color signal, each is converted into a digital signal, sequentially subjected to scan conversion processing, and then returned to the corresponding analog signal. The present invention is characterized in that three types of color difference signals are demodulated from the analog carrier color signal that has been subjected to the progressive scan conversion process, and corresponding analog three primary color signals are created from each of these color difference signals and the analog luminance signal that has been subjected to the progressive scan conversion process. A progressive scan conversion device for color television signals.