JPH03294891A - Display device - Google Patents

Abstract

PURPOSE:To accomplish the display of high quality by providing a means which generates a parabolic voltage to correct a brightness deviation in synchronism with the change of the deflection angle in the horizontal and vertical directions of an electron beam on a cathode-ray tube and means which corrects a focusing voltage in synchronism with the voltage. CONSTITUTION:The parabolic wave voltages generated by parabolic voltage generating means 9 and 10 are impressed on a black level adjusting means 6, so that the black level of the cathode-ray tube 3 is dynamically changed. Consequently, the brightness deviation caused by positions on a screen can be corrected and improved. Similarly, the parabolic wave voltage is impressed on the means 12 to change the focusing voltage in synchronism with the parabolic wave voltage, so that the focusing voltage is dynamically changed at its periphery. Consequently, the defocusing caused by the positions on the screen is corrected an improved. Therefore, the brightness deviation caused by the positions on the screen is corrected and also the focusing difference caused by the positions on the screen is decreased by simultaneously providing these means. Thus, the display screen having the high quality can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a display device using a cathode ray tube that requires display of many gradations and fine detail.

[Conventional technology]

In the conventional device, as described on pages 262 to 263 of NHK Television Technology Textbook (Part 1) (published on April 10, 1989), by applying a fixed bias to G1, the black Adjusting levels.

With conventional devices, due to thinner products and flatter screens, the deflection angle has become larger than before, the curvature has become smaller, and the distance from the electron beam emission point to the display point varies depending on the position of the screen. In addition to the deterioration of brightness, the deterioration of focus was noticeable at the periphery of the screen. For this reason, when the same character or the like is displayed on the entire surface, the periphery becomes dark and out of focus, which requires improvement.

The conventional device will be explained below with reference to FIG. Third
In the figure, 1 is a video amplifier, 2 is a video output circuit,
3 is a cathode ray tube, 4 is a deflection circuit, 5 is a high voltage generation circuit, 1
2 is a black level adjustment volume. To obtain brightness with the conventional display device shown in FIG. 3, a black level voltage corresponding to G is set using the black level adjustment volume 12, and the amplitude of the cathode voltage is changed based on this. At the same time, the electron beam of the cathode ray tube 3 is deflected by the deflection circuit 4 based on the horizontal/vertical synchronizing signal to emit light at a desired position for display. However, since the screen curvature of the cathode ray tube is different from the deflection curvature, the electron beam reaches a longer distance at the periphery of the screen, resulting in deterioration in brightness and blurring of focus.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, there is a difference in brightness between the center and the periphery of the screen, and even when the same color is displayed, the color tone appears different. Furthermore, even when the same characters are displayed, there is a problem in that the peripheral parts appear even more blurred.

An object of the present invention is to provide a display device that enables high-quality display.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a means for generating a parabolic voltage for correcting a brightness deviation in synchronization with changes in the horizontal and vertical deflection angles of an electron beam in a cathode ray tube. A means for correcting the focus voltage is provided.

[Effect]

In the present invention, by applying the parabolic wave voltage generated by the voltage generating means to the black level adjusting means, the black level of the cathode ray tube changes dynamically, and as a result,
It is possible to correct and improve brightness deviations depending on the position on the screen. Similarly, by applying a parabolic wave voltage to a means for changing the focus voltage in synchronization with the parabolic wave voltage,
The focus voltage changes dynamically at the periphery, making it possible to correct and improve focus blur caused by position on the screen.

By providing these means at the same time, brightness correction and focus characteristics can be improved.

〔Example〕

An embodiment of the present invention will be described below.

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a waveform diagram of main signals of FIG. 1.

In FIG. 1, 1 to 5 are the same as in FIG. 3. 6 is a black level adjustment circuit, 7 is a horizontal sawtooth signal (H-3A
W), 8 is a vertical sawtooth wave signal (V-3AW), 9
．． 10 is a parabola generation circuit, 11 is a parabola generation circuit 9
, 10, and 12 is a focus modulation section.

The deflection circuit 4 detects H-3AW7 and V-8AW8, the parabola generation circuits 9 and 10 generate a parabola waveform, and the parabola superimposition circuit 11 generates an H/V parabola signal. By applying this H/V parabolic signal to G1 of the cathode ray tube 3 via the black level adjustment circuit 6, higher brightness can be obtained at the periphery of the screen than at the center.

Therefore, even if there is a decrease in brightness at the periphery of the screen as described above, higher brightness can be obtained than at the center. Brightness deviation due to position can be corrected.

Similarly, by applying the H/V parabolic signal to the focus G of the cathode ray tube 3 via the focus modulation section 12, a higher focus voltage can be obtained at the periphery of the screen than at the center. Therefore, it is possible to change the focus of the electron lens composed of G, and the focus characteristics can be improved even in the peripheral area.

〔Effect of the invention〕

According to the present invention, it is possible to correct the brightness difference between the periphery and the center of the screen, that is, the brightness deviation depending on the position on the screen, so even when the same color is displayed, the color tone may appear different. do not have. Furthermore, since the focus voltages at the periphery and center are also corrected, there is little difference in focus depending on the position on the screen. Therefore, a high quality display screen can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a block diagram of an embodiment of the present invention.
3 is a block diagram of a conventional display device. FIG. 3 is a block diagram of a conventional display device. 1... Video amplifier 2... Video output circuit 3.
... Braun tube 4 ... Deflection circuit 5 ... High pressure generation circuit 6 ... Black level adjustment circuit 7 ... H-8A
W8...V-8AW9.10...Parabolic generation circuit 11...Parabolic superimposition circuit 12...Focus voltage modulation section

Claims (1)

[Claims] 1. A parabolic wave generation circuit having a parabolic waveform synchronized with changes in the horizontal and vertical deflection angles of an electron beam in a cathode ray tube, a black level adjusting means for changing the black level according to an applied voltage, and A display device comprising means for modulating a focus voltage in synchronization to simultaneously correct brightness deviation and focus characteristics depending on a position on a screen.