JPH11212510A - Cathode-ray tube driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the resolution by suppressing the extension of a working area where an electron beam is emitted from a cathode and reducing the spot size of the electron beam on a screen. SOLUTION: A data processor 1 generates an X deflection signal Vx, a Y deflection signal Vy, and a luminance signal Vz. Signals Vx and Vz drive a deflecting coil 9 as an X-side deflecting current ICX and a Y-side deflecting current ICY through a pincushion distortion correction circuit 7 and a deflection amplifier 8 to control the upper position of a CRT 10. Signals Vx and Vy are supplied to the CRT 10 as a focus voltage VF through correction voltage generation circuits 2 and 11, an addition circuit 4, and a focus amplifier 6. With respect to the signal Vz, the potential is supplied to a cathode 21 as VOZ through a video amplifier 5, and an inversely proportional potential is supplied to a G2 electrode as VT 7 through an inverting video amplifier 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube driving apparatus which drives an electron gun for a cathode ray tube, and in particular, suppresses the spread of the spot size of an electron beam.

[0002]

2. Description of the Related Art A conventional electron gun for a color cathode ray tube (hereinafter, referred to as a color cathode ray tube).
In a driving method using an electric current, a potential of a first grid (hereinafter, referred to as G1) electrode is fixed, a potential of a cathode is lowered, and a current is taken out by a cathode driving method. Fixed,
One of the G1 drive systems has been used in which the potential of the G1 electrode is raised to take out a current.

[0003]

However, in any case, since the drive is performed by one electrode, when the frequency becomes high, the drive voltage does not fluctuate. Therefore, it is necessary to lower the cutoff voltage (Ekco) at the limit on the frequency characteristics of the control circuit of the cathode potential Ek. As shown in FIG. 5, there is a problem that the current Ik that can be extracted with the reduction of the cutoff voltage is reduced.

[0004] Further, as a problem of driving by one electrode, there is a problem that an operation region area (hereinafter, referred to as a working area) in which electrons are emitted from a cathode is inevitably widened as the current Ik increases. This working area is connected to C through the main lens of the electron gun.
There is a proportional relationship with the spot size (hereinafter referred to as VSS) of the electron beam imaged on the RT phosphor screen. That is, as shown in FIG. 5, the working area serving as the object diameter with respect to the main lens expands as the current Ik increases. For this reason, as shown in FIG.
At the same time, which deteriorates the resolution particularly in a high current region.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a display device capable of suppressing the spread of a working area where an electron beam is emitted from a cathode, and suppressing the spread of VSS.

[0006]

According to the present invention, a first drive signal is applied to a cathode of a cathode ray tube, and a second drive signal is applied to a second grid of the cathode ray tube. , And the first and second drive signals are formed so that the potential fluctuations of the cathode and the second grid are in inverse proportion to each other.

[0007] By inverting the potential supplied to the cathode of the electron gun and applying it to the second grid (hereinafter referred to as G2) electrode, the working area of the electron beam emitted from the cathode is suppressed from being widened. Can be
Further, the spread of VSS can be suppressed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration of an embodiment to which the present invention is applied. In this embodiment, for ease of explanation, it is assumed that a color CRT display is driven only by a luminance signal. The data processor denoted by 1 generates an X deflection signal Vx, a Y deflection signal Vy and a luminance signal Vz. X deflection signals Vx and Y
The deflection signal Vy is supplied to the dynamic focus correction voltage generation circuit 2, the pincushion distortion correction circuit 7, and the focus displacement correction voltage generation circuit 11. Luminance signal V
z is supplied to the video amplifier 5, the focus displacement correction voltage generation circuit 11, and the inversion video amplifier 12.

The dynamic focus correction voltage generating circuit 2 generates a focus correction voltage VDF based on the position of the electron beam on the CRT 10 from the supplied X deflection signal Vx and Y deflection signal Vy. The generated focus correction voltage VDF is supplied to the focus displacement correction voltage generation circuit 11.

The focus displacement correction voltage generating circuit 11 calculates the displacement of the focus voltage based on the X deflection signal Vx, the Y deflection signal Vy, the luminance signal Vz and the focus correction voltage VDF. The displacement amount is supplied to the adding circuit 4 as a focus displacement voltage VC. In the focus / offset voltage generation circuit 3, an offset voltage VOF is generated to give a pedestal potential to the focus voltage, and is output to the addition circuit 4.

In the adder circuit 4, the focus displacement voltage VC
And the offset voltage VOF are added, and the addition result is supplied to the focus amplifier 6 as a focus voltage VMX. In the focus amplifier 6, the supplied focus voltage VMX is amplified to the optimum voltage of the CRT 10, and supplied to the CRT 10 as the focus voltage VF.

In the pincushion distortion correction circuit 7, the CRT
Deflection signals VCX and VCY for correcting the pincushion distortion of the ten images are generated. Generated deflection signal V
CX and VCY are supplied to the deflection amplifier 8. In the deflection amplifier 8, the supplied deflection signals VCX and VCY are converted into CRTs.
It is amplified to be at the designated position of 10. The amplified deflection signals VCX and VCY drive the deflection coil 9 as an X-side deflection current ICX and a Y-side deflection current ICY.
0 is controlled on the screen.

In the video amplifier 5, the supplied luminance signal VZ is amplified by the optimum voltage of the CRT 10, and the luminance signal VOZ is amplified.
Is supplied to the cathode of the CRT 10. In the inversion video amplifier 12, the supplied luminance signal VZ is inverted,
It is amplified at the optimal voltage of the CRT 10. The luminance signal VZ
Is supplied to the G2 electrode of the CRT 10 as the inverted luminance signal VTZ. At this time, the inverted luminance signal VTZ is supplied to the G2 electrode included in the CRT 10. The G1 electrode is grounded. Thus, a signal inversely proportional to the cathode and the G2 electrode is supplied.

CRT 10 according to an embodiment of the present invention
FIG. 2 shows an electrode structure of the electron gun. As shown in FIG.
This electrode structure includes a cathode 21, a G1 electrode, a G2 electrode,
It is composed of six electrodes: a third grid (hereinafter, referred to as G3) electrode, a fourth grid (hereinafter, referred to as G4) electrode, and a fifth grid (hereinafter, referred to as G5) electrode. C
The RT 10 performs screen display by forming a beam of thermoelectrons radiated from the cathode 21 with an electrostatic lens of an electron gun and scanning an RGB fluorescent screen on a tube surface. At this time, the luminance modulation is realized by varying the current Ik of the electron beam hitting the phosphor screen. The adjustment of the current amount Ik is performed by a prefocus lens constituted by an electrode group of the cathode 21, the G1, G2 and G3 electrodes. In addition, a main lens is configured by an electrode group of the G3 electrode, the G4 electrode, and the G5 electrode. The main lens focuses the electron beam emitted from the prefocus lens on the tube surface.

The conventional electron gun has a G1 electrode, a G2 electrode, and a G electrode.
The potentials of the three electrodes and the G5 electrode are fixed. Also,
The cathode 21 adjusts a current Ik proportional to the luminance in synchronization with the video signal VOZ. That is, in the case of the cathode drive system, the potential Ek of the cathode 21 is equal to the current Ik
The current Ik increases as the voltage decreases from the cutoff voltage Ekco corresponding to = 0. This reduction is referred to as the drive amount Ed, and Ek = Ekco-Ed holds.

In one embodiment of the present invention, the cathode 21
The electrodes other than the G2 electrode and the G2 electrode have the same potential relationship as that of the conventional electron gun. The potentials supplied to the cathode 21 and the G2 electrode form the luminance signal VOZ and the inverted luminance signal VTZ so that the potential fluctuations are simultaneously inversely proportional. In this way, the current Ik is controlled.

In general, as shown in FIG. 5, the working area is substantially determined by the drive ratio (Ed / Ekco) without depending on the cutoff voltage Ekco. On the other hand, as the potential of the G2 electrode increases, the current Ik emitted at the same drive rate increases. Taking advantage of this characteristic, the potential of the G2 electrode is fixed and the drive amount Ed alone is not changed as in the related art. That is, in the present invention, the current I
When increasing k, the electron gun is driven such that the potential Ek of the cathode 21 is lowered from the cutoff voltage Ekco, and in synchronization with this, the potential of the G2 electrode is raised in reverse.

Thus, as shown in FIG. 3, it is possible to draw out a larger current than before while suppressing the expansion of the working area without being largely influenced by the frequency characteristics of the control circuit for controlling the potential Ek of the cathode 21. . Each point in FIG. 3 is at the time of the potential of each G2 electrode in FIG. That is, FIG.
As shown in FIG.
In the drive method, VSS rises as the current Ik rises.
Is spreading. However, as shown in FIG.
According to the drive method of the present invention, although the VSS spreads with the rise of the current Ik, the spread can be suppressed.

In this embodiment, a general electron gun G
The same can be realized by replacing the two electrodes with those having a three-hole division shape so that the current of three electron beams can be independently controlled from an integrated part.

The present invention is not limited to the electron gun of the above-described embodiment, but can be similarly applied without depending on the basic shape of the electron gun. For example, the present invention can be applied to an in-line (horizontal) type, a delta type, a three-electron gun type, a single-electron gun type, and a trinitron type electron gun type.

[0021]

According to the present invention, the same object diameter can be obtained without largely depending on the fluctuation of the current Ik, the VSS on the screen can be suppressed, and the resolution can be improved. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a display device to which the present invention is applied.

FIG. 2 is a schematic diagram of an electrode structure of an electron gun to which the present invention is applied.

FIG. 3 is a schematic diagram illustrating a variation of a working area according to the present invention.

FIG. 4 is a schematic diagram for explaining fluctuation of a beam spot size according to the present invention.

FIG. 5 is a schematic diagram for explaining variation of a conventional working area.

FIG. 6 is a schematic diagram for explaining a change in a conventional beam spot size.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Data processor, 2 ... Dynamic focus correction voltage generation circuit, 3 ... Focus offset voltage generation circuit, 4 ... Addition circuit, 5 ... Video amplifier, 6 ... Focus amplifier , 7: pincushion distortion correction circuit, 8: deflection amplifier, 9: deflection coil, 10: CRT, 11: focus displacement correction voltage generation circuit, 12: inverted video amplifier

Claims (2)

[Claims] 1. A first drive signal is applied to a cathode of a cathode ray tube, and a second drive signal is applied to a second grid of the cathode ray tube, wherein the cathode and the second grid are applied. Wherein the first and second drive signals are formed such that the potential fluctuations are inversely proportional to each other. 2. The method according to claim 1, further comprising: three cathodes; three cathodes each corresponding to the three cathodes; and a correspondence between the cathode and the second grid. A cathode-ray-tube driving device, wherein the first and second drive signals are formed so that potential fluctuations between the two become inversely proportional to each other.