JPH06105182A - Display device - Google Patents

Abstract

PURPOSE:To obtain a display picture with high picture quality by applying a brightness correction voltage from a voltage generating means to a black level adjustment means so as to change dynamically the black level of a cathode ray tube and to apply similarly a focus correction voltage to a focus voltage change means. CONSTITUTION:An H/V synchronizing signal inputted to a deflection circuit 4 is inputted to an address generating circuit 7 while being synchronized to generate a correction position address to a black level correction frame memory 8 and a focus correction frame memory 9. A black level correction value is fed to a black level adjustment circuit 6 and a focus correction value is fed to a cathode ray tube 3 via a focus voltage modulation circuit 10 respectively among specified or correction values from the memories 8, 9 obtained in this way to correct brightness deviation depending on the position on a screen. Similarly the focus correction voltage is applied to a focus G3 of the cathode ray tube 3 via the circuit 10 to acquire an optional correction voltage in the entire picture area. That is, the three brightness deviations are corrected on the position of the screen and the focus voltage is corrected on the entire picture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device using a cathode ray tube which requires many gradation display and fine display.

[0002]

2. Description of the Related Art A conventional device is an NHK television technical textbook (top) (published April 10, 1989), pages 262 to 2
As described on page 63, the black level is adjusted by applying a fixed bias to G1.

The conventional device has a larger deflection angle than ever before due to a thinner product and a flat screen.
The curvature becomes smaller, the distance from the electron beam emission point to the display point differs depending on the position of the screen, and the deterioration of the focus and the deterioration of the focus were conspicuous in the peripheral portion of the screen.
For this reason, when the same character or the like is displayed on the entire surface, it is dark in the periphery and the focus is out of focus, which requires improvement.

Further, in the case of a large-sized display device, the coating unevenness of the fluorescent substance is conspicuous, so that it is necessary to improve it.

A conventional device will be described below with reference to FIG.

In FIG. 2, 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 circuit, and 12 is a black level adjusting volume.

In order to obtain the brightness in the conventional display device shown in FIG. 2, the black level voltage corresponding to G2 is set by the black level adjusting volume 12, and the amplitude of the cathode voltage is changed with reference to this.

At the same time, the electron beam of the cathode ray tube 3 is deflected by the deflection circuit 4 on the basis of the horizontal and vertical synchronizing signals to emit light at an arbitrary position for display. However, since the screen deviated curvature of the cathode ray tube is different from the deflected curvature, the reach distance of the electron beam becomes long in the peripheral portion of the screen, which causes deterioration of brightness and defocusing.

[0009]

In the above-mentioned prior art, the brightness differs between the central part and the peripheral part of the screen, and even if the same color is displayed, the color tones look different. In addition, even when the same characters are displayed, there is a problem that they are more blurred in the surrounding area.

An object of the present invention is to provide a display device capable of high quality display.

[0011]

In order to achieve the above object, according to the present invention, a means for recording and generating a voltage for correcting a luminance deviation in synchronization with changes in horizontal and vertical deflection angles of an electron beam in a cathode ray tube. At the same time, a means for synchronously recording and generating a voltage for correcting the focus voltage is provided.

[0012]

In the present invention, the black level of the cathode ray tube is dynamically changed by applying the brightness correction voltage generated by the voltage generating means to the black level adjusting means, and as a result, the brightness deviation due to the position on the screen is corrected. Can be improved. Similarly, by applying the focus correction voltage to the means for changing the focus voltage in synchronization with this, it is possible to correct and improve the focus blur in the peripheral portion.

By providing these means at the same time,
It is possible to correct brightness and improve focus characteristics.

[0014]

EXAMPLES An example of the present invention will be described below.

FIG. 1 is a block diagram showing an embodiment of the present invention.

In FIG. 1, 1 to 5 are the same as in FIG. 6 is a black level adjusting circuit, 7 is an address generating circuit,
Reference numeral 8 is a black level correction frame memory, 9 is a focus correction frame memory, and 10 is a focus voltage modulation circuit.

The H / V sync signal input to the deflection circuit 4 is synchronized and input to the address generation circuit 7 for generating an address, whereby the frame memory 8 for black level correction is generated.
And the address of the correction position of the focus correction frame memory 9 is generated. Based on this address, the specified value or the correction value is read from the black level correction frame memory 8 and the focus correction frame memory 9,
The black level correction value is applied to the black level adjustment circuit 6, and the focus correction value is applied to the cathode ray tube 3 via the focus voltage modulation circuit 10. By applying the black level correction voltage to G1 of the cathode ray tube 3, it is possible to obtain an arbitrary black level at an arbitrary position. Therefore, even if there is the above-described decrease in the brightness in the peripheral part of the screen, the black level correction value that makes the brightness equal to the central part is recorded to correct the brightness deviation due to the position on the screen. be able to.

Similarly, by applying the focus correction voltage to the focus G3 of the cathode ray tube 3 via the focus modulation circuit 10, it is possible to obtain an arbitrary correction voltage over the entire screen. Therefore, the focal point of the electron lens composed of G3 can be arbitrarily changed, and
Focus characteristics can be improved.

[0019]

According to the present invention, it is possible to correct the brightness difference with respect to the center of the screen, that is, the brightness deviation due to the position on the screen, so that even if the same color is displayed, the color tones do not appear different. . Further, since the focus voltage is also corrected over the entire screen, the difference in focus due to the position on the screen is small. Therefore, a high quality display screen can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Video amplifier, 2 ... Video output amplifier circuit, 3 ... Braun tube, 4 ... Deflection circuit, 5 ... High voltage generation circuit, 6 ... Black level adjustment circuit, 7 ... Address generation circuit, 8 ... Black level frame memory, 9 ... Focus frame memory, 1
0 ... Focus voltage modulation circuit.

Claims (1)

[Claims] 1. A signal generating circuit synchronized with a change in horizontal and vertical deflection angles of an electron beam in a cathode ray tube, a synchronous recording / reading circuit for the signal, and black level adjusting means for changing a black level according to an applied voltage. A display device characterized in that means for modulating the focus voltage in synchronization with this is provided to simultaneously correct the brightness deviation and the focus characteristic depending on the position on the screen.