JPS614372A - Display device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a display device for displaying images, and particularly to a display device using a cathode ray tube.

<Prior art> Conventionally, display devices using cathode ray tubes emit electron beams horizontally and
It scans in both vertical directions and displays a two-dimensional image. For example, in the NTSC system, one frame of image is composed of approximately 500 horizontal scanning lines in the vertical direction. Therefore, when viewing a large-screen cathode ray tube from a close distance, the scanning lines appear to be separated, which significantly degrades the image quality.

The object of the present invention is to provide a display device that can obtain high-quality images.

<Example> FIG. 1 shows an example of the present invention. FIG. 1 is a control circuit diagram of the display device of this embodiment.

In FIG. 1, 1 is a cathode ray tube (hereinafter referred to as CRT), and 2 is an electron gun, into which a video signal Min is input. 3 vertical deflection coils, 4 a horizontal deflection coil, and 5 a horizontal deflection drive circuit to which a horizontal deflection signal H8 is input. 6 is a vertical deflection drive circuit, and 7 is a mixing circuit in which the vertical deflection signal VSK noise signal NS is superimposed and output to the vertical deflection drive circuit B.

(As is known, the cathode ray modulated by the video signal Vin is deflected by the vertical deflection coil 3 and the horizontal deflection coil 4, and the CRT face plate signal is superimposed, so that the horizontal scanning line is very small in the vertical direction. deviate.

Figure 2 shows the horizontal scanning line on the display surface 1).
Figure 3 shows the probability of occurrence. In the figure, L1 to Ln indicate horizontal scanning lines with no displacement in the vertical direction. The beam spot of the horizontal scanning line is slightly displaced randomly by the noise signal NS, and the probability of its occurrence in the vertical direction is as shown in FIG.
The probability distribution when 0 is glass-distributed around Ln as the center and therefore overlaps with the adjacent scanning line and combined is shown by the broken line in Figure 6 (the amplitude value of the uniform 0 noise signal is The probability distribution is adjusted to be uniform,
The maximum value is set so as not to exceed the adjacent undisplaced scanning line on the display screen.Also, the band of the noise signal NS is set to a sufficiently high band with respect to the horizontal scanning frequency (15.75 KH2 in NTSC). The scanning structure is converted to a continuous array, making it difficult to see the scanning structure and improving the quality of the displayed image.

As another method of configuring a spatial low-pass filter in the vertical deflection direction, it is also possible to provide an auxiliary vertical deflection coil separate from the vertical deflection coil and to apply a noise signal to this auxiliary deflection coil. be.

Note that the occurrence probability distribution does not need to be completely uniform in the vertical direction; it is sufficient to have continuity to the extent that the scanning structure is not visible.

<Effects> As described in detail above (according to the display device of the present invention,
The discrete scanning structures become an apparently continuous array, making the scanning structures difficult to see even on a large screen, and significantly improving the quality of the optically displayed image.

[Brief explanation of the drawing]

FIG. 1 is a control circuit diagram of the display device of this embodiment, FIG. 2 is a diagram showing the displacement of a beam spot on the display surface of a CRT, and FIG. 6 is a diagram showing the occurrence probability distribution of a noise signal in the vertical direction. It is a diagram. In the figure, 1 is a cathode ray tube, 2 is an electron gun, 6 is a vertical deflection coil, 4 is a horizontal deflection coil, 7 is a mixing circuit, and NS is a noise signal.

Claims (1)

[Claims] A display device using a cathode ray tube, characterized in that a discrete scanning structure is converted into an apparently continuous array by configuring a spatial low-pass filter in a direction perpendicular to a horizontal scanning line.