JPS61144183A - Picture display unit - Google Patents

Abstract

PURPOSE:To maintain regular position of an electron beam by providing two electron beam position detecting electrodes having wedge-shaped electron beam passing holes reversed to each other in vertical direction, and feeding back the difference between the normal operation and actual operation of the position of electron beam to a part of a display element driving circuit. CONSTITUTION:Two electron beam position detecting electrodes 50, 50' separated electrically from a vertical converging electrode 3' are arranged outside of the effective picture of the electrode 3' placed in the screen side of a vertical polarization electrode 4 of a display element. Landing position in vertical direction of electron beam is detected by providing a long wedge-shaped electron beam passing hole 51 in vertical direction in one of detecting electrodes and providing a similar wedge-shaped electron beam passing hole 51' reversed its vertical direction in another detecting electrode. Signals from electron beam position detecting electrodes 50, 50' when the electron beam is irradiated onto regular position on the screen are stored in a memory circuit. Signals from electron beam position detecting electrodes and a signal of the memory circuit are compared at the time of actual operation, and the difference is fed back to a part of a display element driving circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention generates an electron beam for each division when a screen on a screen is vertically divided into a plurality of divisions, and generates an electron beam for each division. The present invention relates to an apparatus for displaying a plurality of lines by vertically deflecting a beam to display a television image as a whole.

Conventional technology Conventionally, cathode ray tubes have been mainly used as display elements for displaying color television images, but conventional cathode ray tubes have a very long depth compared to the screen size, making it difficult to receive thin television images. It was impossible to create a machine. Furthermore, although KL display elements, plasma display devices, liquid crystal display elements, and the like have recently been developed as flat display elements, all of them are insufficient in terms of performance such as brightness, contrast, and color display.

Therefore, Japanese Patent Application No. 56-20618 (Japanese Unexamined Patent Publication No. 57-571) proposed a method for achieving a flat display device using electron beams.
135590), a new display device was proposed.

This method generates an electron beam for each section when the screen is vertically divided into multiple sections, and displays multiple lines by deflecting each electron beam vertically for each section. However, as a whole, a television run image is displayed. First, a basic configuration example of the image display element used here will be explained with reference to FIG.

This display element includes, in order from the back to the front, a back electrode 1, a line cathode 2 as a beam source, and vertical focusing electrodes 3, 3'.
, vertical deflection electrode 4, horizontal focusing electrode 6, horizontal deflection electrode 7,
A beam accelerating electrode 8 and a screen plate 9 are arranged, and these are housed in the evacuated interior of a flat glass bulb (not shown). The line cathode 2 as a beam source is stretched horizontally so as to generate an electron beam distributed linearly in the horizontal direction. In the figure, only four wires 2-2 are shown). In this embodiment, it is assumed that 15 pieces are provided. Let's call them 2i~2yo. These line cathodes 2 are, for example, 1
An oxide cathode material for thermionic emission is coated on the surface of a tungsten wire with a diameter of 0 to 20 μφ. and,
These line cathodes 2A to 2Y are heated so as to generate a thermionic electron beam by passing an electric current through them, and as described later, the line cathodes 2A and 2Y emit electron beams sequentially for a certain period of time. controlled to do so.

The back electrode 1 suppresses generation of electron beams from line cathodes 2 other than the line cathode 2 that is controlled to emit electron beams for a certain period of time, and directs the generated electron beams only in the forward direction. It has the effect of pushing out. This back electrode 1 may be formed by a coating film of a conductive material adhered to the inner surface of the rear wall of the glass pulp. In addition, these back electrodes 1
Instead of the linear cathode 2, a planar electron beam emitting cathode may be used.

The vertical focusing electrode 3 is a conductive plate 11 having a horizontally long slit 1o facing each of the line cathodes 2i to 2yo, and takes out the electron beam emitted from the blown cathode 2 through the slit 10, and directs the electron beam vertically. focus in a direction.

Electron beams for one horizontal line (36 pixels) are taken out at the same time.

In the figure, only one section in the horizontal direction is shown. The slits 10 may be provided with crosspieces at appropriate intervals in the middle, or may be substantially a row of through holes arranged horizontally at small intervals (nearly touching intervals). It may also be configured as a slit. The vertical focusing electrode 3' is also similar.

A plurality of vertical deflection electrodes 4 are arranged horizontally in the middle of each of the slits 10, and each of the vertical deflection electrodes 4 is composed of conductors 13 and 13 provided on the upper and lower surfaces of the insulating substrate 12. ing. Then, a vertical deflection voltage is applied between the opposing conductors 13 and 13',
Deflect the electron beam vertically. In this embodiment, a pair of conductors 13 and 13' deflect the electron beam from one line cathode 2 to positions corresponding to 16 lines in the vertical direction.

The 16 vertical deflection electrodes 4 constitute 16 pairs of conductors corresponding to each of the 16 line cathodes 2, and in the end, the electron beam is deflected to draw 240 horizontal lines on the screen 9. do.

Next, the control electrodes 6 are composed of conductive plates 16 each having a vertically long slit 14, and a plurality of control electrodes 6 are arranged in parallel on a horizontal plane with predetermined intervals. In this embodiment, 180 conductive plates 15a to 15n for control electrodes are provided (only nine are shown in the figure). Each of the control electrodes 6 separates and extracts the electron beam into two picture elements in the horizontal direction, and controls the amount of electron beam passing therethrough in accordance with a video signal for displaying each picture element.

Therefore, if 180 conductive plates 15a to 15n for control electrode 6 are provided, 360 picture elements can be displayed per horizontal line. In addition, in order to display images in color, each picture element is displayed with phosphors of three colors R, G, and H, and each control electrode 6 has two picture elements of R, G, and B. Each video signal is applied sequentially.

In addition, 180 pairs of video signals for one line (2 pixels per pair) are simultaneously applied to each of the 180 conductive plates 15a to 15n for the control electrode 6, so that the video for one line is displayed at one time. Ru.

The horizontal focusing electrode 6 is composed of a conductive plate 17 having a plurality of vertically long slits 16 (180 slits) facing the slits 14 of the control electrode 6, and collects electrons for each picture element divided in the horizontal direction. Each beam is focused horizontally into a narrow electron beam.

A plurality of horizontal deflection electrodes 7 are electrically conductive plates 18 arranged vertically on both sides of the slit 16,
18', each electrode 18, 18
A six-step horizontal deflection voltage is applied to the screen 9 to deflect the electron beam of each picture element in the horizontal direction.
Above, the two sets of R, G, and B phosphors are sequentially irradiated to emit light.

In this embodiment, the deflection range is two picture elements wide for each electron beam.

The acceleration electrode 8 is composed of a plurality of conductive plates 19 provided horizontally at the same position as the vertical deflection electrode 4.
The electron beam is accelerated to impact the screen 9' with sufficient energy.

The screen 9 is constructed by applying a phosphor 20 that emits light when irradiated with an electron beam to the back surface of a glass plate 21, and adding a metal back layer (not shown).

The phosphors 20 are provided with two pairs of phosphors of three colors, R2G and B, for each slit 14 of the control electrode 6, that is, for each horizontally divided electron beam. It is applied in vertical stripes.

In FIG. 1, the broken lines drawn on the screen 9 indicate divisions in the vertical direction that are displayed corresponding to each of the plurality of line cathodes 2, and the two-dot chain lines correspond to each of the plurality of control electrodes 6. Indicates the horizontal division displayed. As shown in an enlarged view in FIG. 6, one section partitioned by these two has R, G, and B phosphors 20 for two pixels in the horizontal direction.
It has a width of 16 lines in the vertical direction.

The size of one section is, for example, 1 parrot in the horizontal direction and 101111 in the vertical direction.

Note that in FIG. 6, the length in the horizontal direction is greatly expanded relative to the length in the vertical direction for clarity.

Further, in this embodiment, only one pair of R, (1, H phosphor 20 for two picture elements is provided for one control electrode 6, that is, one electron beam, but of course, one pair of phosphors 20 for two picture elements is provided. A picture element or three or more picture elements may be provided. In that case, the control electrode 5 has R, G,
A B video signal is sequentially applied, and horizontal deflection is performed in synchronization with the B video signal.

Next, the basic configuration of a drive circuit for displaying television images on this display element will be explained with reference to FIG. First, a driving portion for irradiating the screen 9 with an electron beam to emit raster light will be described.

The power supply circuit 22 is a circuit for applying a predetermined bias voltage (operating voltage) to each electrode of the display element, -v1 to the back electrode 1, v3 to the vertical focusing electrodes 3, 3. ■3', v6 for horizontal focusing electrode 6, v8 for accelerating electrode 8, screen 9
A DC voltage of v9 is applied to.

Next, a composite video signal of a television signal is applied to the input terminal 23, and a synchronization separation circuit 24 separates and extracts a vertical synchronization signal V and a horizontal synchronization signal H.

The vertical deflection drive circuit 40 includes a vertical deflection counter 25.
Memory 27 for vertical deflection signal storage. It is constituted by a digital-to-analog converter 39 (hereinafter referred to as a DA converter). The input pulse of the vertical deflection drive circuit 4o is as follows:
A vertical synchronizing signal V and a horizontal synchronizing signal H shown in FIG. 8 are used. The vertical deflection counter 26 (8 bits) is reset by the vertical synchronizing signal V and counts the horizontal synchronizing signal H. This vertical deflection counter 25 is counted during an effective scanning period (in this case, 24
This count output is supplied to the address of the memory 27. The 0 memory 27 outputs vertical deflection signal data (here, 10 pits) corresponding to each address, and the D- V shown in FIG. 8 in the A converter 39.

V' is converted into a vertical deflection signal. . In this circuit, 24
There is a memory address for storing a vertical deflection signal corresponding to each line of OH minutes, and by storing regular data in the memory every 1eH minutes, 16 levels of vertical deflection signals can be obtained.

On the other hand, the line cathode drive circuit 26 uses the vertical synchronization signal V and the output of the vertical deflection counter 26 to create line cathode drive pulses [I to YO]. FIG. 9a shows the relationship between the vertical synchronizing signal V, the horizontal synchronizing signal H, and the lower five bits of the vertical deflection counter 26. Figure 9 shows 16 using these signals.
Linear cathode drive pulse for each H In FIG. 9, LSB indicates the lowest pit, (LSB+
1) means the bit one higher than the LSB.

The first line cathode drive pulse [A'] can be created using an R-8 flip-flop or the like using the vertical synchronization signal V and the output (LSB+4) of the vertical deflection counter 26.
The line cathode drive pulses [A' to 'Y'] can be obtained by using a shift register to transfer the line cathode drive pulses [A] using the inverted version of the output (LSB+3) of the vertical deflection counter 26 as a clock. can. This drive pulse is converted into a line cathode drive pulse [I to Y] which is inverted and has a low potential only during each pulse period, and a high potential of about 20 volts during other periods, and each line cathode It can be added to 2i to 2yo.

Each line cathode 2i to 2yo is heated by a current flowing through it during the high potential of the driving pulse [i to yo].
The heated state is maintained so that electrons are emitted during the low potential period (I to Y). As a result, 16 line cathodes 2-2
From Y to Y, electrons are emitted only during the 1aH period when a low potential drive pulse [I to Y] is applied to each of them. During the period when a high potential is applied, the back electrode 1 and the vertical focusing electrode 3
Since the high potential applied to the linear cathodes 2i to 2yo is more positive than the potential at the position of the linear cathodes 2 determined by the bias voltage applied to the linear cathodes 2i to 2yo, No electrons are emitted from yo. Thus, in the line cathode 2, electrons are sequentially emitted from the upper line cathode 2a toward the lower line cathode 2y every 1eH period during the effective vertical scanning period.

The emitted electrons are pushed forward by the back electrode 1, pass through the opposing slits 1o of the vertical focusing electrode 3, and are focused in the vertical direction to form a flat electron beam.

Next, the line cathode drive pulses [A to Y] and the vertical deflection signal V
, V/ will be explained using FIG. The vertical deflection signals V, V/ are each line cathode pulse [A~
During the 16H period of [Y]], it changes by 1H and changes in 16 steps. The vertical deflection signals V and V' both have a center voltage of v4, and are configured to change in opposite directions such that 2 increases sequentially and 2/ decreases sequentially. These vertical deflection signals V and V' are applied to the electrodes 13 and 13' of the vertical deflection electrode 4, respectively, and as a result, the electron beams generated from the respective line cathodes 2I to 2Y are vertically divided into 16 steps. As described above, on the screen 9, one electron beam is deflected so that a raster of 16 lines is sequentially drawn one line at a time from the top.

As a result of the above, electron beams are emitted for 16H periods in order from the one above the 16 line cathodes 2A to 2Y, and each electron beam is sequentially emitted for one line from the top to the bottom within 16 sections in the vertical direction. As a result, the electron beam is vertically deflected one inch at a time from the first line at the upper end to the 240th line at the lower end on the screen e, and a total of 240 lines of raster are drawn.

The electron beam thus vertically deflected is horizontally divided into 180 sections by the control electrode 5 and the horizontal focusing electrode 6 and extracted. Figure 6 shows one of these categories. The amount of electron beam passing through each section is controlled by a control electrode 6, and is focused in the horizontal direction by a horizontal focusing electrode 6 to become one thin electron beam.
The light is deflected horizontally in six steps by the horizontal deflection means described below, and is sequentially irradiated onto each of the R, G, and B phosphors 2o corresponding to two picture elements on the screen 9. FIG. 2 shows the vertical and horizontal divisions. Control electrodes 6 15a to 16, respectively
The phosphors corresponding to n are R, G, and B for two picture elements, but for convenience of explanation, one picture element is R1, G1, . B1 and the other R2
, G2. Let's call it B2.

Next, the horizontal deflection drive circuit 41 is composed of a horizontal deflection counter (11 bits), a memory 29 storing horizontal deflection signals, and a DA converter 38. The input pulse to the horizontal deflection drive circuit 41 is synchronized with the vertical synchronizing signal V and the horizontal synchronizing signal H, as shown in FIG. 7, and uses a pulse 5H having a repeating frequency six times that of the horizontal synchronizing signal H.

The horizontal deflection counter 28 is reset by the vertical synchronizing signal V and counts the horizontal six-fold pulse θH. This horizontal deflection counter 28 is used 6 times during 1 HO.
(7) Between K 240 HX 6 / H = 1440
The count output is supplied to an address in the memory 29. The memory 29 outputs horizontal deflection signal data (8 pits in this case) according to the address.
A D/A converter 38 converts the signal into a horizontal deflection signal such as h/ as shown in FIG. This circuit has memory addresses for storing horizontal deflection signals corresponding to each of 6 x 240 lines, and by storing 6 pieces of regular data for each line in the memory, 6-step horizontal waves are generated in 1H period. A deflection signal can be obtained.

As shown in Fig. 7, this horizontal deflection signal is a pair of horizontal deflection signals ri and h' that change in 6 steps, both of which have a center voltage of v7, where h decreases sequentially and h' increases sequentially. They change in opposite directions as they move forward. These horizontal deflection signals h and h/ are respectively applied to the electrode 18 of the horizontal deflection electrode 7.
and 18'.

As a result, each horizontally segmented electron beam is applied to the R, G, B, R of the screen 9 during each horizontal period.

G, B (R1, G1.B1.R2, G2.B2)
The light is horizontally deflected so that the phosphors are sequentially irradiated with H7e.

Thus, in each line raster, the horizontal direction 18
The electron beam for each section of 0 is R1, G1°B1. R2
, G2. Each phosphor 2o of B2 is sequentially irradiated with an electron beam R1, G for each horizontal section of each line.
1. B1. R2, G2. By modulating the B2 video signal, a color television image can be displayed on the screen 9.

Next, the modulation control portion of the electron beam will be explained.

First, the composite video signal applied to the television signal input terminal 23 is applied to the color demodulation circuit 3o, where the R-Y
and B-Y color difference signals are demodulated, the G-Y color difference signals are matrix-synthesized, and further, they are combined with the luminance signal Y to generate R, G, and B primary color signals (hereinafter R, G, and B). (referred to as a video signal) is output. These R, G, and B video signals are processed by 180 sample and hold circuit sets 31a to 31.
added to n. Each sample and hold circuit set 31a to 3
1n is for R4, G1, B, and R2, respectively.

It has B2JlllZe sample and hold circuits for G2. These sample and hold outputs are respectively added to holding memory sets 32a to 32n.

On the other hand, the reference clock oscillator 33 is constituted by a PLL (phase-locked loop) circuit, etc., and in this embodiment, the reference clock 6f80 is six times as large as the color subcarrier '8C.
and a double reference clock 2'sc is generated. The reference clock is controlled to always have a constant phase with respect to the horizontal synchronizing signal H. Reference clock 2f. is added to the deflection pulse generation circuit 42, and 6 of the horizontal synchronizing signal H
Double signal 6H and signal switching pulse r1 + (Jl
+bl p r2+q2. I am getting a B2 pulse. On the other hand, the reference clock efgc is applied to the sampling pulse generation circuit 34, where it is delayed by one clock period by a shift register, etc., so that the horizontal period (e 3
．． 1080 sampling pulses Ra1 to Bn during the effective horizontal scanning period (approximately 60μ) of
2 are generated sequentially, followed by one transfer pulse t. These sampling pulses Ra1 to Bn2 correspond to each picture element when one line of the video to be displayed is divided into 360 picture elements in the horizontal direction, and their positions are always constant with respect to the horizontal synchronizing signal H. controlled by.

These 1080 sampling pulses Ra1 to B2 are respectively connected to 180 sample and hold circuit sets 31a to 3.
1n, and as a result, each sample-and-hold circuit set 31a to 31n has R1, G1 . B1.
R2, G2. Each B2 video signal is individually sampled and held. That sample held 180
Group R7,G.

B1. R2, G2. After the B2 video signal is sampled and held for one line, 180 sets of memo IJ 32 a~
32n, the signals are transferred all at once by a transfer pulse t, and held here for the next horizontal period. This retained R1.
G1. B1. R2, G2. The signal B2 is applied to switching circuits 35a-35n. switching circuit 3
5a to 35n each have R1°G1. B1. R2,G
2. It is composed of a tri-state or analog gate having individual input terminals of B2 and a common output terminal that sequentially switches and outputs them.

The output of each switching circuit 35a-35n is applied to 180 sets of pulse width modulation (PWM) circuits 37a-37n, where R1. G1. B
lv R2t G2 , Bp The reference pulse signal is pulse width modulated according to the magnitude of the image signal and output. The repetition period of the reference pulse signal is determined by the signal switching path r1. q1. b1. r2. (It is desirable that the pulse width is sufficiently smaller than the pulse width of J2°B2, for example, 1
:1o to about 1:100 is used.

The outputs of the pulse width modulation circuits 37a to 37n are individually applied to the 180 conductive plates 15a to 15H of the control electrode 6 of the display element as control signals for modulating the electron beam. Switching is controlled simultaneously by five switching pulses '1 eQ1+b1 *'2+q2*b2 applied from the switching pulse generation circuit 36. The switching pulse generation circuit 36 receives signals from the deflection pulse generation circuit 42 described above (r1 eq1+b1+r2. q2+t)2
H7 is controlled by dividing each horizontal period into 6
The switching circuits 35a to 35n are switched by R1, G1°B1. R2, G2. Each video signal of B2 is time-divided and output sequentially, and the pulse width modulation circuits 37a to 37
The switching signal r1. +911b1p”2
vb2+q28 sacrifice.

What should be noted here is that the switching circuits 35a to 3
R1.5n. G1. B1. Switching the supply of video signals of R2, G2°B2, and electron beams R4, G1 . B1. The horizontal deflection of R2, G2 and B2 for switching the irradiation to the phosphor is synchronously controlled so that they completely match both in timing and order. As a result, when the electron beam is irradiating the R1 phosphor, the irradiation amount of the electron beam is controlled by the R4 video signal, and the G1. B1. R2, G2. B
2 are controlled in the same way, and R, , G4 .
B1. R2°G2. B2 The light emission of each party light is the R of that picture element.
1, G1°B1. R2, G2. Each picture element is controlled by the B2 video signal, and each picture element is displayed by emitting light according to the input video signal. Such control is performed simultaneously for 180 sets (2 picture elements each) for one line, and an image of 360 picture elements for one line is displayed, and an additional 24 picture elements are displayed.
This is done sequentially from the upper line on the 0 minute line.
One image will be displayed on the screen 9.

The above operations are performed on one input television signal.
This is repeated for each field, and as a result, a moving television image is displayed on the screen 9 in the same way as a normal television receiver.

Problems to be Solved by the Invention In the above-mentioned image display device, the landing position of each electron beam on the screen is strictly determined, and positional deviation in the vertical direction can be reduced by reducing the raster interval. This shift in the landing position of the electron beam is caused by changes over time in the vertical deflection waveform or expansion and contraction over time of each electrode that makes up the display element. However, in order to keep the landing position constant, it is necessary to make the deflection waveform amplification circuit extremely precise and the electrode material to be made of a material that has very little expansion and contraction. is not practical because it leads to increased power consumption and cost.

Means for Solving the Problems In the present invention, at least one of the electrodes arranged closer to the screen than the vertical deflection electrode of the display element is provided outside the effective screen, electrically separated from the electrodes inside the effective screen. Two electron beam position detection electrodes are provided, one of which has a vertically long wedge-shaped electron beam passing hole, and the other one has a similar wedge-shaped electron beam passing hole with the vertical direction reversed. By this, the vertical landing position of the electron beam is detected, and the signal from the electron beam position detection electrode when the electron beam is irradiated on the correct position on the screen is stored in a memory circuit, and the electron beam position is detected during actual operation. According to the image display device of the present invention, the signal from the detection electrode and the signal stored in the memory circuit are compared and the difference is fed back to a part of the display element drive circuit. It has two electron beam position detection electrodes with wedge-shaped electron beam passing holes opposite to each other in the direction, and from these electrodes an electron beam position signal that is unaffected by increase or decrease in the amount of electron beam is obtained, and the normal electron beam position is detected. By comparing the signal with the electron beam position signal during actual operation and feeding back the difference to a part of the display element drive circuit, the vertical landing position of the electron beam on the screen is always at the correct position. It is controlled so that it is maintained.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

As shown in FIG. 1, two electron beam position detection plates electrically separated from the electrode 3' are placed outside the effective screen of the vertical focusing electrode 3' arranged on the screen side of the vertical deflection electrode 4 of the display element. Electrodes 50.50' are arranged. These electrodes 50
．． 50' are electrically isolated from each other and have vertically long wedge-shaped electron beam passing holes (slits) 51 and 51' with a length equivalent to the distance between the pair of vertical deflection electrodes 4. The electrodes 60 and so' are formed in a wedge shape that is opposite to each other in the vertical direction.

And to detect the vertical landing position,
A pilot electron beam 62 having a horizontal spread sufficient to achieve a uniform electron density in the horizontal direction of the electrodes 50 and 50' is placed at specific positions near the upper and lower ends of the wedge-shaped slits 61 and 61'. Deflect vertically to irradiate. Specifically, as shown in FIG. 3, for example, in addition to the period in which an image is displayed in the n-th vertical section Kn, a line cathode drive pulse is generated to display Kn during the vertical retrace period of each field. Correspondingly, the vertical deflection waveform is also set such that the electron beam irradiates the vicinity of the upper end of Kn during the vertical retrace period of the mth field, and the electron beam irradiates the vicinity of the lower end of Kn during the vertical retrace period of the m+1th field. The drive waveform may be set such that

The beam electrons thus irradiated onto the electron beam position detection electrodes 50, 50' become currents I, I2 and are guided to the current-voltage conversion circuits 53 and 53, as shown in FIG. , voltage E4. Converted to E2. Here, the current I1.
I is inversely proportional to the amount of the electron beam passing through the wedge-shaped slit, and always changes while maintaining a constant relationship of 11+l2. Shifc 11'tte, (1l-12)
/(11+12)ffxbchi(El-E2)/(E1+
By performing the calculation E2), it is possible to obtain an irradiation position signal without being affected by an increase or decrease in the amount of electron beam irradiation.

Now, the feedback system for compensating the landing position of the electron beam can be configured as shown in FIG. After sample-holding at 54', the A/D converter 55 performs time division A-D conversion, and the result is stored in the memory 67 via the CPU 5a.

This stored data is converted into position data by calculations by the CPU, and compared with initial position data stored in the memory 67 in a similar manner at the time of optimal adjustment of the landing position. If the position data D2 of the electron beam irradiated to the upper end of the unit and the position data D3 of the electron beam irradiated to the lower end of the unit are initial position data D0. D
1, D2〉Do and D )D or D2
If D3〈Dl, it is determined that the entire Kn has changed up and down as shown in Figure 4a, and D2〉Do.
If D3<Dl or D2<Do and D3>Dl, it is determined that the amplitude of Kn has expanded or contracted as shown in Figure 4.0 Then, depending on each case, the data difference is stored in the deflection data memory. Appropriately add or subtract from the vertical deflection data for Kn stored in 27, D2=D
0 and D3=D7.

As described above, it is possible to control the vertical irradiation position of the electron beam so that it is always maintained at the normal position at the time of optimum adjustment.

Effects of the Invention As described above, according to the present invention, the landing position of the electron beam irradiated onto the screen in the vertical direction is detected by the electron beam position detection electrode disposed inside the display element, and the electron beam is detected on the screen. The signal from the electron beam position detection electrode stored in the memory circuit when the electron beam is irradiated to the correct position of the electron beam is compared with the signal from the electron beam position detection electrode during actual operation, and the difference is used to drive the display element. By feeding back to a part of the circuit, it is possible to control the electron beam so that it is always irradiated to the correct position on the screen, and it is possible to control the characteristics of the drive circuit over time or the electrodes that make up the display element over time. It is possible to compensate for changes in the landing position of the electron beam in the vertical direction caused by expansion and contraction, and to maintain a constant raster interval in the vertical direction to prevent uneven brightness.

[Brief explanation of drawings]

Figures 1a and l) are enlarged exploded perspective views showing the arrangement of electron beam position detection electrodes of an image display element used in an image display device according to an embodiment of the present invention, and diagrams for explaining the electron beam position detection principle thereof. Figure 2 is a block diagram showing the configuration of the feedback system, Figure 3 is a waveform diagram showing the vertical deflection waveform and linear cathode driving pulse waveform for irradiating the pilot electron beam, and Figure 4 is a waveform diagram showing the electron beam. An enlarged view to explain the change in the beam position in the vertical direction, FIG. 6 is an exploded perspective view of an image display element used in a conventional image display device, and FIG. 6 is an enlarged view of the fluorescent surface of the image display element. 7 is a block diagram showing the basic configuration of the drive circuit of the image display element, FIG. 8 is a waveform diagram for explaining the operation of the vertical deflection drive, and FIG. 9 is a waveform diagram for explaining the operation of the line cathode drive circuit. Figure 10 is a waveform diagram of each drive signal.
FIG. 11 is a waveform diagram for explaining the operation of the horizontal deflection drive circuit. 2.2i~2yo... Line cathode, 3'...
Vertical focusing electrode, 4... Vertical deflection electrode, 6... Mountain/beam flow control electrode, 7... Horizontal deflection electrode, 9
...Screen, 10...Slit,
2o... fluorescent substance, 23... input terminal,
24... synchronization separation circuit, 25... mark/vertical deflection counter, 26... line cathode drive circuit, 27...
...Memory, 28...Counter for horizontal deflection,
29... Memory, 30... River/color demodulation circuit, 3
1a to 31n...Sample and hold circuit, 32
a to 32n: old memory, 33: reference clock oscillator, 34: sampling pulse generation circuit, 35a to 35n: switching circuit,
36... River switching pulse generation circuit, 37a-3
7n...PWM circuit, 38...D/A
Converter, 39...D/A converter, 40...
- Vertical deflection drive circuit, 41... Horizontal deflection electrode circuit, 42... Deflection pulse generation circuit, 50.5
0'...Electron beam position detection electrode, 61.51
'...Wedge-shaped slit, 53.53'...
・Current-voltage conversion circuit, 54.64'...Sample/hold circuit, 66...A/D converter, 56.
...CPU, esy...Memo 1. Name of agent Patent attorney Toshio Nakao 1 person Figure 1 Figure 4 (OL) Dl > DO Dl > Dzu (b) υ5〈Dl Vt< ρzuDe < D. 2% 03>Dt Figure 6 Figure 7 Figure 8 Figure 9 Figure LSB+-knee=/6H (b novo:

Claims (3)

[Claims] (1) a plurality of line cathode electron beam sources, a screen having a phosphor that emits light when irradiated with the electron beam, and a focusing electrode that focuses the electron beam generated by the electron beam source; The display element includes an electrostatic deflection electrode that deflects the electron beam on the way to the screen, and a control electrode that controls the emission intensity by controlling the amount of the electron beam irradiated onto the screen. Of the electrodes arranged closer to the screen than the vertical deflection electrode of this display element, at least one electrode is provided outside the effective screen, and two electrodes electrically separated from the electrode inside the effective screen are provided to An image display device characterized by being able to detect a beam position. (2) One of the electron beam position detection electrodes is provided with a vertically long wedge-shaped electron beam passing hole, and the other one is provided with a similar wedge-shaped electron beam passing hole with the vertical direction reversed. An image display device according to claim 4 characterized by: (3) A memory circuit stores the signal from the electron beam detection electrode when the electron beam is irradiated onto a regular position on the screen, and the signal from the electron beam detection electrode and the memory circuit during actual operation. By comparing the signals and feeding back the difference to a part of the display element drive circuit, the electron beam is controlled so that it is always irradiated to the correct position on the screen. The image display device according to scope 1.