JPH0219094A - Color picture display device - Google Patents

Abstract

PURPOSE:To prevent production of color deviation by multiplying an index signal outputted proportional to an electron beam modulated by a video signal with a signal obtained from an electron beam modulation signal passing through a circuit having an inverse characteristic to the electron beam modulation characteristic. CONSTITUTION:A means 70 is used, which multiplies an index signal I(t) outputted proportional to the electron beam quantity modulated by a video signal and a signal obtained from the electron beam modulation signal processed by a circuit having an inverse characteristic to the electron beam modulation characteristic. Thus, the modulation signal component is eliminated by multiplying the index signal with a signal obtained from the electron beam modulation signal passing through a circuit having an inverse characteristic to the electron beam modulation characteristic and an index signal outputted proportional to the electron beam quantity with no modulation is obtained. Thus, the amplitude and phase of the signal are always kept constant and a picture without color shear is obtained without deviation of timing of a color signal applied to a beam modulation electrode or missing of the color signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color image display device used in television receivers, computer terminal displays, and the like.

2. Description of the Related Art As a prior art flat cathode ray tube developed by the present applicant, there is a structure shown in FIG. In reality, each electrode is housed in a vacuum envelope (glass container), but the vacuum envelope is omitted in the figure to make the internal electrodes clear. Further, in order to clarify the horizontal and vertical directions of the screen on which images, characters, etc. are displayed, the horizontal direction (H) and vertical direction (V) are illustrated on the face plate portion.

In the figure, 10 is a vertically long linear cathode with an oxide cathode material coated on the surface of a tungsten wire.
A plurality of them are arranged independently at equal intervals in the horizontal direction. On the opposite side of the face plate part 28 with the linear cathode 10 in between, there are long horizontally extending strips that are close to the linear cathode 10 and are electrically separated from each other at equal pitches in the vertical direction on the insulating support ll. Vertical scanning electrodes 12 are arranged.

Next, between the linear cathode 10 and the face plate 28, the linear cathodes 10 are sequentially arranged from the linear cathode 1'0 side.
A planar first grid electrode (hereinafter referred to as Gl) 13 having an opening at a portion corresponding to the intersection of the G1 electrode 13 and the vertical scanning electrode 12, and a second grid electrode (hereinafter referred to as G2) 1 having an opening similar to the G1 electrode 13.
4. Place the third grid (hereinafter referred to as G3) 15. CI,
The 02 electrodes 13 and 14 are for generating an electron beam from the linear cathode IO, and the G3 electrode 15 is for shielding the electric field from the subsequent electrode and the beam generating electric field.

Furthermore, a G4 electrode 16 is arranged, and its opening is longer in the horizontal direction than in the vertical direction. After the G4 electrode 16, two vertical deflection electrodes 17 and 18 having similar openings are arranged. Figure 3 (A) shows the horizontal cross section of Figure 2, and Figure 3 (B)
shows a vertical cross section. As shown in the figure, vertical deflection electrodes are formed by vertically shifting the axes of the openings of the two electrodes 17 and 18. Vertical deflection electrode 17.18
At the rear stage, a plurality of vertically long electrodes are provided between the linear cathodes 10 toward the face plate portion 28 . Fig. 2 shows a three-stage case as an example, where each electrode is a first horizontal deflection electrode (hereinafter referred to as DHI) 19, a second horizontal deflection electrode (hereinafter referred to as DH2) 20, and a third horizontal deflection electrode (hereinafter referred to as 03). 21, and every other horizontal deflection electrode 19-21 is connected to a common bus bar 22, 23, 24 in the horizontal direction.

Each of these horizontal deflection electrodes has a horizontal focusing function as well as a deflecting function. A light emitting layer consisting of a fluorescent screen 27 and a metal back electrode 26 is formed on the inner surface of the face plate portion 28 . On the phosphor screen 27, the front (R),
Green (G) and blue (B) phosphor stripes are formed through a black guard band.

Next, the operation of the color cathode ray tube will be briefly explained.

The linear cathode 10 is heated by passing a current through it, and approximately the same potential as the cathode 10 is applied to the vertical scanning electrode 12 and the Gl electrode 13. At this time, if a potential higher than the potential of the cathode 10 is applied to the G2 electrode 14 so that the beam passes through each electrode aperture, an electron beam is emitted from the cathode IO toward the Gl and 02 electrodes. Here, to control the beam amount, the linear cathode 10 or C1
This is done by changing the potential of the electrode 13. G2 electrode 1
The beam passing through the aperture 4 is connected to the G3 electrode 15 and the G4 electrode 1.
6. Focused in the vertical direction by an electrostatic lens formed between the vertical deflection electrodes 17 and 18, and DHI and DH2 in the horizontal direction.
, D) [3.

On the other hand, the horizontal deflection is DHI (19), DH2 (20),
Common bus 22.23. connected to DH3 (21).
24 by applying a sawtooth wave, a triangular wave, etc. at a horizontal scanning frequency.

Further, vertical scanning is performed as follows (see FIG. 4). Emission of the electron beam from the linear cathode 10 is as follows:
This can be controlled by making the space potential surrounding the cathode more positive or negative than the potential of the linear cathode 10. That is, the potential of the vertical scanning electrode 12 is changed to the beam emission (hereinafter referred to as O
It can be controlled by switching to a potential that is N) or shut off (hereinafter referred to as 0FF). In the case of the current television system that uses an interlaced system, in the first field, a predetermined deflection voltage is applied to the vertical deflection electrodes 17 and 18 for one field period, and the vertical scanning electrode 12A is applied for one horizontal scanning period. A beam ON voltage is applied only to IH (hereinafter referred to as IH), and a beam generation electric field is applied to the other vertical scanning electrodes. After IH has passed, I is applied only to the vertical scanning electrode 12B.
The H beam ON voltage and then the IH beam ON voltage are sequentially applied to the vertical scanning electrodes, and when 122 at the bottom of the screen is completed, the vertical scanning of the first field is completed. In the next second field, the polarity of the deflection voltage applied to the vertical deflection electrodes 17 and 18 is reversed, and this is applied for l fields. The beam ON voltage applied to the vertical scanning electrode is then applied in the same manner as in the first field.

At this time, the amplitude of the deflection voltage applied to the vertical deflection electrodes 17 and 18 is adjusted so that the horizontal scanning line of the second field is located between the horizontal scanning line positions of the beam caused by the vertical scanning of the first field. , interlacing is possible.

Next, a signal processing method for applying a video signal to the beam modulation electrode of the flat plate cathode ray tube will be explained with reference to FIG. First, a timing pulse generator 44 generates timing pulses for driving circuit blocks to be described later, based on a television synchronization signal input manually from a synchronization signal input terminal 42.

The three primary color signals ER, EG, and Ee of R, G, and B that have been demodulated in advance are converted into A by a timing pulse.
The /D converter 43 converts the signal into a digital signal, and stores the IH signal in the first line memory 45.

Once all the IH interleave signals are stored, the signals are transferred to the second line memory 46, and the next IH interleaved signals are further stored in the first line memory 45. Second line memory 46
The signal transferred to is stored in IH memory, during which time it is converted to the original analog signal by the D/A converter 47, and this signal is amplified and applied to the beam modulation electrode of the cathode ray tube.

By the way, in order to display a color image with this flat cathode ray tube, the timing at which the electron beam impacts each color phosphor of R, G, and B, and the timing at which each color modulation signal is applied to the beam modulation electrode of the cathode ray tube are determined. must match exactly. The applicant has previously shown a method for achieving this using an index method. This method can basically be implemented by configuring as shown in FIG.

In FIG. 6, the index signal obtained from the flat cathode ray tube 50 can be obtained from the emission of a phosphor specially arranged and coated on the phosphor screen, or from the R coated on the image display area.
It can be obtained optically from the emission of either G or B phosphors. Alternatively, a method of electrically detecting the beam current may be used. When obtaining optically, the pulsed light emission obtained by scanning a phosphor screen with an unmodulated electron beam is converted into an electrical signal by a photoelectric conversion element 51, amplified, and then shaped into a rectangular wave signal by a waveform shaping circuit 54. do. This signal is further passed through a phase variable means 55 such as a waveform memory or a COD delay element, and then used as an index signal.

On the other hand, the entire image display area of the phosphor screen is scanned with an unmodulated beam, and the pulsed light emitted from any of the R, G, or B phosphors is received by the photoelectric conversion element 56, converted into an electrical signal, and amplified. Band pass filter (BPF) 5
8 and then waveform-shaped to produce a beam position signal.

The phase relationship between the index signal and the beam position signal obtained in this manner is determined by adjusting the phase of the index signal to a position where an appropriate phase difference occurs as shown in FIG.
5, and the time difference between the pulse rising edge of the index signal and the pulse rising edge of the beam position signal is 1+.

t2. h3... are measured by the phase difference measuring circuit 60 and stored in the memory 61 as digital data.

By performing this operation over the entire image display area for each scan line, the timing at which the beam impacts each strip of phosphor over the entire image display area is obtained. Therefore, when displaying an actual image, the time difference data t+, t2 . t3...
are sequentially read out for each scanning line using the index signal as a reference, and each time difference tl, t2. At the time when t3... has elapsed, that is, at the timing when the beam impacts each strip of phosphor, it is demodulated in advance and sent to the video signal processing circuit 6.
A color image can be displayed by sequentially applying R, G, and B color signals prepared in No. 3 IH memory to the beam modulation electrode.

Problems to be Solved by the Invention However, in the above-mentioned index method, it is necessary to obtain a stable index signal when displaying an image as well as when measuring a phase difference. For this purpose, for example, an area for obtaining an index signal may be provided outside the image display area, and that area may be constantly scanned with an unmodulated beam. However, due to the operating principle of this flat-plate cathode ray tube, a dedicated linear cathode must be provided in order to always scan with an unmodulated beam. This requires extra spatial space and reduces the effective image display area ratio of the cathode ray tube.

Furthermore, if an index signal is obtained from an area scanned by a beam modulated with a video signal without using the above method, the index signal amplitude will not be constant due to modulation, and the phase may fluctuate. , it is possible that there will be no signal. FIG. 8 shows how the index signal is disturbed by the video signal. The electron beam is modulated by the video signal Ed(t), and the amount of beam reaching the fluorescent screen varies depending on the structure of the electron gun.
d(t)). Index signal 1 (
t) It can be seen that both phases are disturbed.

Therefore, there is a problem that a shift occurs in the application timing of each color signal based on the index signal, or the application timing is lost, resulting in color misregistration.

An object of the present invention is to provide a color image display device that solves the problems of the prior art.

Means for Solving the Problems The present invention provides an index signal output in proportion to the amount of C-modulated electron beam by a video signal, and an electron beam modulation signal that is connected to a circuit having characteristics opposite to the electron beam modulation characteristics. By using a means of multiplying the signal processed by
It solves the problems of the coming technology.

The index signal output in proportion to the amount of electron beam modulated by the working video signal is the index signal output in the case of no modulation, multiplied by the modulation signal component according to the modulation characteristics of the electron beam. By multiplying and combining the signals obtained by passing the electron beam modulation signal through a circuit with characteristics opposite to those of the electron beam modulation characteristics, the modulation signal component is removed, and the output is proportional to the amount of unmodulated electron beam. An index signal is obtained.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a flat cathode ray tube used in a color image display device of the present invention and a drive section related to an index. - As an example, a case is shown in which a short afterglow phosphor for obtaining an index signal is arranged outside the image display area of the cathode ray tube 50 and above the display area.

Based on the index signal obtained by scanning with an unmodulated electron beam in advance, R, G, and B of the entire image display area are
The operation of storing the light emission timing of each phosphor in the memory 61 is performed in the same manner as in the prior art.

When displaying an image, the light emission timing stored in the memory 61 is read out based on the index signal,
This is the timing for applying each color signal to the beam modulation electrode. Video signal EJ temporarily stored in the video signal processing circuit 63
I, Ec, and Ee become a serial signal Ea(t) according to their respective application timings and are sent to the beam modulation electrode of the flat cathode ray tube 50 through the amplifier 64 to modulate the electron beam.

As mentioned above, the index signal 1 (t) is disturbed due to modulation, and the index signal without modulation is
5(t), I (t)・I 5(t)K (E
d(t))'. However, when Ed(t)=0, I
In order to prevent (t)=0, it is necessary to superimpose a minute DC signal E@ on the modulation signal. For example, if you shift the bias voltage of the back electrode that makes up the electron gun by E@, you can have the same effect as superimposing E8 on the modulation signal, instead of superimposing Ee directly on the modulation signal. , the bias voltage of the back electrode portion acting only on the index phosphor region may be shifted by E[I. The index signal obtained in this way with the E11 component superimposed can be expressed as follows.

1(t)” I 5(t)K (E a(t)+E e
) On the other hand, adding the DC signal E8 to the modulation signal Ed(t),
Processing of raising the signal to the −1 power using the nonlinear amplifier 72 and further multiplying it by a constant 1/K is performed in a circuit. The signal obtained by this processing can be expressed as follows.

(1/K) (E a(t)+E IIV When the latter signal obtained in this way by the circuit and the index signal I(t) obtained from the cathode ray tube 50 are multiplied by the multiplier 70, I A signal (t)=Il!(t) is obtained, and an index signal containing no modulation signal component is obtained.

Effects of the Invention According to the present invention, an index signal output in proportion to the amount of electron beam modulated by a video signal and an electron beam modulation signal are obtained by passing the electron beam modulation signal through a circuit having characteristics opposite to the modulation characteristics of the electron beam. The video signal component is removed from the index signal by multiplying the index signal by the chrominance signal, and an index signal proportional to the amount of unmodulated electron beam is obtained. The timing of applying the beam to the beam modulation electrode is not shifted or lost, and an image without color shift can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the structure of a flat cathode ray tube used in the image display device of the present invention and a drive unit related to the index, and FIG. 2 is a block diagram of the main part structure for displaying the prior art by the present applicant. FIG. 7 is a signal waveform diagram for explaining a conventional method of obtaining the application timing of a color signal, and FIG. 8 is a waveform diagram showing how the index signal is disturbed. 10... Linear cathode, 12... Vertical scanning electrode, 1
7.18...Vertical deflection electrode, 19.20.21...
Horizontal deflection electrode, 27... Fluorescent screen, 50... Flat cathode ray tube, 51... Photoelectric conversion element, 53... Band pass filter (BPF), 54... Waveform shaping circuit,
55... Phase variable circuit, 60... Phase difference measurement circuit,
61...Memory, 62...Color signal application timing generation circuit, 63...Video signal processing circuit, 70.71...
- Multiplier, 72... Nonlinear amplifier, 73... Adder. Agent's name: Patent attorney Shigetaka Awano Block diagram for one person, Figure 6 is a conventional color image 2 Figure 10...''Folded cathode]]...-1I! ! , ll prong special holiday 12... Vertical foot rest 1 cold 13...] Grid! 15...; t-3 grid 111 poles] 6-4th grid electrician) 17.18--1 call l deflection cage pole] 9-years old ] Water deflection electric current - 2 horizontal deflection @ pole 2] - 3 horizontal deflection @ pole 22.23.24 - 1 common motherboard 26...Metal back electrode 27...Phosphor screen 4...Face Plate moss B d Figure Figure 41--3 Urine 1 White A No. 8 42-1- Teleji synchronization signal Sugar 4 Figure Figure

Claims (1)

[Claims] It has an image display element that scans and emits light with an electron beam on a phosphor screen on which three primary color phosphors of red (R), green (G), and blue (B) or other multiple color phosphors are repeatedly applied in the horizontal direction, Based on a specific signal outputted from the image display element in proportion to the amount of electron beam, the electron beam is driven so as to know the timing at which the phosphor is bombarded, and the specific signal outputted from the image display element and 1. A color image display device comprising means for multiplying an electron beam modulation signal by a signal obtained by processing the electron beam modulation signal with a circuit having characteristics inverse to the electron beam modulation characteristics.