JPS63285084A - Tripple scanning system - Google Patents

Abstract

PURPOSE:To attain high definition of a large-sized television receiver by converting sequentially one line of an input video signal into a high definition video signal for 3 lines, using only a video signal of one line as a non-signal, scanning it by a frequency thrice the horizontal frequency of the input video signal to visualize the result. CONSTITUTION:The input video signal subject to A/D conversion is written sequentially in memories 5, 6 for one line each and the input video signal by one line written already from the memories 5, 6 is read sequentially in the frequency thrice the write frequency. Then the input video signal by one line is converted into high density video signals by 3 lines and only one line of the video signal in the three lines of video signals of the high-density video signals is used as the non-signal and the result is subjected to D/A conversion. The high-density video signal subjected to D/A conversion is scanned by the frequency thrice the horizontal frequency of the input video signal to visualize the signal. Thus, the coarseness of the scanning lines is not made conspicuous without deteriorating the vertical resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a scanning method for improving the image quality of a television receiver.

<Prior art> In general television receivers, one screen is made up of two fields, an odd field shown in FIG. 4(A) and an even field shown in FIG. 4(B), using a 2:1 interlacing system. It consists of

The number of scanning lines on one screen is 525, but on the screen of each field, the number of scanning lines is 262.5 per 1/60 seconds, so in a large television receiver, There was a problem in that the roughness of the scanning lines was noticeable.

In order to improve this, large television receivers double the number of scanning lines by repeatedly scanning the video signal of the previous line to form an l field of 525 lines, as shown in Figure 5. Some cameras use the so-called double scan (non-interlaced) method.

However, in the double scan method, in which the video signal of the previous line is repeatedly scanned, the roughness of the scan line is no longer a concern, but when the same video signal is scanned twice, 525 lines are scanned. In order to increase the number of lines and scan the same position in each field, one screen ends up consisting of 262.5 video signals, which is half of 525, and the odd and even fields are separated. By scanning the position of the screen, one screen can be divided into five
There was a problem in that the vertical resolution was inferior to that of a general interlaced television receiver consisting of 25 lines.

<Objective of the Invention> The present invention has been made in view of the above-mentioned points, and an object of the present invention is to make the roughness of scanning lines less noticeable without deteriorating the vertical resolution.

<Structure of the Invention> In order to achieve the above-mentioned object, the present invention sequentially writes an A/D converted input video signal to a memory line by line, and writes the already written l from the memory.
The input video signal for the line is
By sequentially reading the input video signal at twice the frequency, the input video signal for one line is converted into the same high-density video signal for three lines, and one line of the three lines of the video signal of this high-density video signal is After making only the video signal of D
/A conversion, and this D/A converted high-density video signal is scanned at a frequency three times the horizontal frequency of the input video signal to create an image.

According to the above configuration, an input video signal for one line is converted into a high-density video signal for three lines, one line of which is left with no signal, and only the remaining two lines are visualized. Therefore, the scanning line density of each field is double that of the interlace method, and the scanning position is shifted in each field, making it possible to maintain the so-called interlace effect that utilizes the afterimage effect of the eye.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of main parts of a television receiver according to an embodiment of the present invention, and FIG. 2 is a signal waveform diagram of each part of FIG. 1. In FIG. 1, the R signal is representatively shown among the R, G, and H primary color signals that are input video signals, and the other primary color signals are also processed by the same circuit as in FIG.

In FIG. 1, l is an A/D converter that A/D converts the R signal provided from a matrix circuit (not shown), and 2 is a horizontal synchronization signal of three times the frequency based on a horizontal synchronization signal synchronized with the R signal. 3 is a synchronization/clock generation circuit that generates a clock for writing or reading data into and from the memory;
．． A first switching circuit 7 provides a high-density R that is read out alternately from each line memory 5, 6.
A second switching circuit that supplies a signal to the blanking circuit 8; 9 is a D/A converter that converts the high-density R signal from the blanking circuit 8; 4 is each switching circuit 3, 7 and each line memory 5; This is a memory control circuit 4 that controls .6.

The R signal shown in FIG. 2(B) is converted into a digital signal by the A/D converter 1 and given to the first switching circuit 3. D), the first .
are applied to the second line memories 5.6, respectively.

The R signal for one line from the first switching circuit 3 is written into one line memory 5 (6) according to the 14.3 MHz write clock, and at the same time, the R signal from the other line memory 6 (5) is already written. R for one line
4, where the signal is three times the frequency of the write clock;
It is read out according to a 2.9 MHz read clock. Therefore, the signals read out alternately from the first and second line memories 5.6 become the same high-density R signal for three lines, as shown in FIGS. 2(E) and 2(F), respectively.

This high-density R signal is applied to the blanking circuit 8 via the second switching circuit 7. In this blanking circuit 8, the R of the third line of the same high-density R signal for three lines is
The signal is blanked and there is no signal, as shown in Figure 2 (G).
It is applied to the D/A converter 9 as a high-density R signal shown in FIG. 15,75x3=47.25kHz) and visualized.

FIG. 3 is a diagram showing the scanning of the triple scan method of this embodiment, in which (A) is an odd field, and (B) is an odd field.
indicate even fields.

In the triple scan method of this embodiment, as mentioned above, one line's worth of R signals are sent to three scans via the line memory 5.6.
The high-density R signal for one line is set, and the third line of the high-density R signal for three lines is made non-signal by the blanking circuit 8, so the first and second lines of the high-density R signal Two lines will be visualized, and the third line will not be visualized. Therefore, each field is composed of 525 signals, which is twice as many as in the interlace method. Moreover, unlike the double scan (non-interlace) method shown in FIG. 5, the scanning position of each field is shifted. As shown in FIG. 3(C), one screen consists of 1050 lines.

In this way, in the triple scan method of the present invention, the scanning line density is twice that of the interlaced method, improving the roughness of the scanning lines, and since the scanning position of each field is shifted, it reduces the afterimage effect on the eyes. This means that the interlace effect used can be maintained, and the vertical resolution will also be improved compared to the double scan method.

In the above embodiment, three of the three lines of high-density R signals are
Although the line has no signal, the present invention is not limited to this. The line may be left with no signal.

<Effects of the Invention> As described above, according to the present invention, one line of an input video signal is sequentially converted into a three-line high-density video signal through a memory, and the three-line high-density video signal is converted into a three-line high-density video signal. After making only one line of the video signal of the video signal non-signal,
Since this high-density video signal is scanned at a frequency three times the horizontal frequency of the input video signal and converted into a video, it is possible to double the scanning line density compared to the interlaced method, and also compared to the double scan method. This makes it possible to improve the vertical resolution, which is extremely effective in improving the image quality of large television receivers.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the main parts of a television receiver according to an embodiment of the present invention, Fig. 2 is a signal waveform diagram of each part of Fig. 1, and Fig. 3 shows a scanning diagram of the embodiment of Fig. 1. Diagram for explanation,
FIG. 4 is a diagram for explaining interlaced scanning, and FIG. 5 is a diagram for explaining double scan (non-interlaced) scanning. l... A/D converter, 5.6... 1st. 2nd line memory, 8...Blanking circuit, 9...D/A converter.

Claims (1)

[Claims] (1) Sequentially write the A/D converted input video signal to the memory line by line, and write the input video signal for the already written line from this memory at a frequency three times the writing frequency. The input video signal for one line is converted into the same high-density video signal for three lines by sequentially reading out the video signal for one line of the three lines of the high-density video signal. The method is characterized in that after the signal is turned into no signal, it is D/A converted, and the D/A converted high-density video signal is scanned at a frequency three times the horizontal frequency of the input video signal to be visualized. Triple scan method.