JP3219424B2 - Television signal converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a television signal converter that converts a TSC television signal into a 16: 9 HDTV television signal.

[0002]

2. Description of the Related Art A method of displaying a television signal having an aspect ratio of 4: 3 on a display device having a wide aspect ratio of 16: 9 is disclosed in Japanese Patent Application Laid-Open No. 63-245076.

In the above-described method, a no-signal area A is generated on both sides of the screen as shown in FIG. For this reason, a fixed gray color is displayed as a border signal in this non-signal area.

FIG. 4 shows a block diagram of a television signal converter for converting an NTSC signal into an HDTV signal. In the figure, reference numeral 1 denotes a double speed conversion unit, which is a composite NTS.
After the C signal is YC separated and A / D converted, the horizontal frequency 1
Double-speed conversion is performed from a signal of 5.734 MHz to a double-speed signal of 31.468 MHz. Reference numerals 2 and 3 denote first and second time axis compression circuits for compressing the respective time axes of the double-speed converted luminance signal Y and color difference signals RY and BY to 14/19.
Is a border signal adding circuit for adding a predetermined gray border signal during a non-signal period that is continuous with the luminance signal compressed by the first time axis compression circuit 2 in the time axis compression circuit. The fixed value generation circuit generates a predetermined fixed value. The circuit 41 and a first multiplexer 42 for selecting the fixed value during the border period shown in FIG. 5A and for selecting and outputting the output of the first time axis compression circuit during periods other than the border period.

[0005] Reference numerals 5 and 6 denote D / A converters for D / A converting the luminance signal to which the border signal is added and the color difference signal output from the second time base compression circuit 3, respectively. 8 is a contour correction circuit for enhancing and correcting the contour of the output, and 9 is a matrix of the output of the contour correction circuit and the color difference signals RY and BY to obtain RGB primary color signals. Matrix circuit for output, 1
Reference numeral 0 denotes a display tube having an aspect ratio of 16: 9.

In the above-described television signal converter, the analog luminance signal (b in FIG. 5) is contour-corrected. However, as shown in FIG. 5c, a peak also appears on the boundary between the border signal portion and the video signal portion on the screen. In addition, there is a drawback that it is unsightly because this changes depending on the content of the video signal.

In addition, jitter occurs due to deterioration in accuracy such as clock reproduction and synchronization separation during VTR reproduction or the like, which causes a problem that a boundary line between the border signal portion and the video signal portion is distorted.

Further, since the border portion is made to have a constant luminance signal, the difference in the average luminance level from the video signal portion causes the display tube 10 to remain unburned.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made in view of the above, and has been made in view of the above, and has been made in view of the above circumstances. A signal conversion device is provided.

It is another object of the present invention to provide a television signal converter in which unburned portions due to a border portion of a display tube are prevented.

[0011]

According to the present invention, there is provided a means for compressing a television signal having a screen aspect ratio of 4: 3 on the time axis, and a predetermined luminance level during a non-signal period following the time axis compressed signal. In a television signal converter for converting an aspect ratio, comprising a border signal adding means for adding a border signal having the same, and a contour correcting circuit for correcting the contour of the output of the border signal adding means, A television signal conversion device including a horizontal low-pass filter and / or a vertical low-pass filter for smoothing a boundary portion between the time-axis-compressed signal and the border signal.

[0012]

[0013]

According to the above-mentioned means, before the contour correction of the luminance signal is performed, the boundary portion between the signal compressed in the time axis in advance and the border signal is smoothed.

Further, the luminance level of the border signal operates so as to change according to the average luminance level of the input video signal.

[0015]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a television signal conversion apparatus according to the present embodiment. The same parts as those in FIG.

The first feature of this embodiment is that the luminance level of the border signal is changed according to the average luminance level of the input video signal. That is, the border signal adding circuit is constituted by the following circuits. An APL detection circuit 43 detects an average luminance level (APL) of the video signal after removing the synchronization signal, and an A / D conversion circuit 44 performs an A / D conversion on this output.
Reference numeral 5 denotes an averaging circuit for averaging the A / D conversion output for a long time (10 minutes to 60 minutes). The averaged data is supplied to the first multiplexer 42. As a result, the amount of the electron beam colliding with the fluorescent film of the display tube becomes uniform during the border period and the image period, so that the unburned portion is prevented.

The second feature is that the boundary between the time-compressed signal and the border signal is smoothed. That is,
A horizontal LPF 11 for smoothing the output of the first multiplexer 42 in the horizontal direction and a vertical LPF 12 for smoothing the output in the vertical direction are provided in series. Is provided.

Accordingly, as shown in FIG. 2A, the second multiplexer 13 selects and outputs the output of the vertical LPF 12 during the 5-dot period including the boundary portion, and outputs the output of the first multiplexer 42 to the horizontal LPF 11 and the vertical LPF 12 during the other periods. To select and output the output via the delay circuit 14 having the same delay amount as the delay time. The horizontal LPF 11 rounds the wavy edge in the horizontal direction of the boundary portion, and no peak occurs as shown in FIG. 2B even if the contour is emphasized by the subsequent contour correction circuit. The vertical LPF 12 also corrects the vertical distortion of the boundary.

As described above, according to the present invention, it is possible to eliminate the distortion of the peak and the boundary generated at the border between the border signal portion and the video signal portion on the screen.

[Brief description of the drawings]

FIG. 1 is a block diagram of a television signal conversion device according to an embodiment of the present invention.

FIG. 2 is a waveform diagram of a main part of FIG.

FIG. 3 is a view showing a display example of a display tube having a wide aspect ratio.

FIG. 4 is a block diagram of a conventional television signal conversion device.

FIG. 5 is a waveform diagram of a main part of FIG. 4;

[Explanation of symbols]

 1 Double-speed converter 2, 3 First and second time axis compressor 4 Border signal addition circuit 8 Contour correction circuit 11 Horizontal LPF 12 Vertical LPF

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-113978 (JP, A) JP-A-63-224481 (JP, A) JP-A-1-194574 (JP, A) JP-A-3-194 1781 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H04N 7/01 H04N 5/445

Claims (1)

(57) [Claims] 1. A means for compressing a television signal having a screen aspect ratio of 4: 3 on a time axis, and a border signal for adding a border signal having a predetermined luminance level to a signal-free period continuous to the signal compressed on the time axis. A television signal converter for exchanging aspect ratios, comprising: an addition unit and a contour correction circuit for correcting a contour of an output of the border signal addition unit. A television signal conversion device including a horizontal low-pass filter and / or a vertical low-pass filter for smoothing a boundary portion with a border signal.