JPH0572696B2 - - Google Patents

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 color television image display, 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. In addition, EL display elements, plasma display elements, liquid crystal display elements, etc. 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, in order to achieve a flat display device using electron beams, the present applicant filed a patent application in 1983-
No. 20618 (Japanese Unexamined Patent Publication No. 57-135590) proposed a new display device.

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, it displays the television image as a whole.

First, a basic configuration example of the image display element used here will be explained with reference to FIG.

This display element is arranged in order from the back to the front.
A back electrode 1, a line cathode 2 as a beam source, vertical focusing electrodes 3, 3', a vertical deflection electrode 4, a beam flow control electrode 5, a horizontal focusing electrode 6, a horizontal deflection electrode 7, a beam accelerating electrode 8 and a screen plate 9. They are housed within the evacuated interior of a flat glass bulb (not shown). If necessary, an auxiliary electrode 3' may be arranged between the vertical deflection electrode 4 and the beam current control electrode 5 as a second vertical focusing electrode or a front horizontal focusing electrode. A line cathode 2 serving as a beam source is stretched horizontally so as to generate an electron beam distributed linearly in the horizontal direction, and a plurality of line cathodes 2 (here, 2
Only four (A to D) are shown). In this embodiment, it is assumed that 15 pieces are provided. Let's call them 2i~2yo. These wire cathodes 2 are constructed by coating the surface of a tungsten wire with a diameter of 10 to 20 μΦ with an oxide cathode material for thermionic emission. And these line cathodes 2-2
The line cathode 2A is heated so as to generate a thermionic electron beam by passing an electric current through it, and as described later, it is controlled to emit an electron beam sequentially from the line cathode 2A for a fixed period of time. Back electrode 1
has the effect of suppressing the generation of electron beams from other line cathodes 2 other than the line cathode 2 that is controlled to emit electron beams for a certain period of time, and pushing out the generated electron beams only in the forward direction. do. The back electrode 1 may be formed by a coating of a conductive material applied to the inner surface of the rear wall of the glass bulb. Further, instead of the back electrode 1 and the linear cathode 2, a planar electron beam emitting cathode may be used.

The rectangular focusing electrode 3 is a conductive plate 11 having a horizontally long slit 10 facing each of the cathode rays 2a to 2yo, and extracts the electron beam emitted from the cathode 2 through the slit 10, and vertically focus in a direction. An electron beam for one horizontal line (368 pixels) is extracted at the same time. In the figure, only one section in the horizontal direction is shown. The slit 10 may be provided with crosspieces at appropriate intervals in the middle, or may be substantially configured as a slit by a row of many through holes arranged horizontally at small intervals (nearly touching intervals). may have been done. Auxiliary electrode 3'
When arranged as the second vertical focusing electrode, the shape is the same structure as the vertical focusing electrode 3' described above,
Further, when disposed as the horizontal focusing electrode, the structure is similar to that of the horizontal focusing electrode 6 described later.

A plurality of vertical deflection electrodes 4 are arranged horizontally in the middle of each of the slits 10, and are each composed of conductors 13 and 13' provided on the upper and lower surfaces of an insulating substrate 12. has been done. And the opposing conductors 13, 13'
A vertical deflection voltage is applied between them to deflect the electron beam in the vertical direction. In this embodiment, the electron beam from one line cathode 2 is vertically deflected to positions corresponding to 16 lines by a pair of conductors 13, 13'. And, by 16 vertical deflection electrodes 4, 15
Fifteen conductor pairs corresponding to each of the book line cathodes 2 are constructed, and the electron beam is ultimately deflected to draw 240 horizontal lines on the screen 9.

Next, the control electrodes 5 are composed of conductive plates 15 each having a vertically long slit 14, and a plurality of control electrodes 5 are arranged horizontally in parallel at 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 5 separates and extracts the electron beam into two picture sets 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, the conductive plates 15a to 15n for the control electrode 5 are
With this arrangement, 360 pixels can be displayed per horizontal line. In addition, in order to display images in color, each picture element is displayed using phosphors of three colors, R, G, and B, and each control electrode 5 has two picture elements of R, G, and B. Each video signal is applied sequentially. In addition, 180 conductive plates 15a to 15n for control electrodes 5
180 sets of video signals for one line (two picture elements per set) are simultaneously applied to each of the lines, and one line of video is displayed at one time.

The horizontal focusing electrode 6 is composed of a conductive plate 17 having a plurality of vertically long slits 16 (180 slits 16) facing the slits 14 of the control electrode 5, and collects electrons for each picture element divided in the horizontal direction. Each beam is focused horizontally into a narrow electron beam.

The horizontal deflection electrode 7 is made up of a plurality of conductive plates 18, 18' arranged vertically on both sides of the slit 16, and each electrode 18, 18' has six levels of horizontal deflection. A voltage is applied to horizontally deflect the electron beam of each pixel, and on the screen 9 two sets of R,
The 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 accelerating electrode 8 is composed of a plurality of conductive plates 19 provided horizontally at the same position as the vertical deflection electrode 4, and accelerates the electron beam so that it collides with the screen 9 with sufficient energy.

The screen 9 is constructed by coating the back surface of a glass plate 21 with a phosphor 20 that emits light when irradiated with an electron beam, and adding a metal back layer (not shown). The phosphor 20 is arranged for each slit 14 of the control electrode 5, that is, for each horizontally divided electron beam.
Two pairs each of three color fluorescent pairs, R, G, and B, are provided and are applied in stripes in the vertical direction. In FIG. 5, 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 5. 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, and 16 lines in the vertical direction. It has a width of
For example, the size of one section is 1 in the horizontal direction.
mm, and the vertical direction is 10 mm.

Note that in FIG. 5, the length in the horizontal direction is greatly expanded relative to the vertical direction to make it easier to change.

Furthermore, in this embodiment, only one pair of R, G, and B phosphors 20 for two picture elements are provided for one control electrode 5, that is, for one electron beam. A single picture element or three or more picture elements may be provided. In that case, R, G, and B video signals for one picture element or three or more picture elements are sequentially applied to the control electrode 5, and horizontal deflection is performed in synchronization with this. will be done.

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,
-V ₁ to the back electrode 1, and -V 1 to the vertical focusing electrodes 3 and 3'.
DC voltages of V ₃ , V ₃ ', V ₆ to the horizontal focusing electrode 6, V ₈ to the accelerating electrode 8, and V ₉ to the screen 9 are applied.

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, a memory 27 for storing vertical deflection signals, and a digital-to-analog converter 39 (hereinafter referred to as a DA converter). As input pulses to the vertical deflection drive circuit 40, a vertical synchronizing signal V and a horizontal synchronizing signal H shown in FIG. 8 are used. The vertical deflection counter 25 (8 bits) receives the vertical synchronization signal V.
It is reset by the horizontal synchronizing signal HW and counts the horizontal synchronizing signal HW. This vertical deflection counter 25 counts the effective scanning period (here, a period of 240 hours) excluding the vertical retrace period of the vertical period,
This count output is supplied to an address in memory 27. Vertical deflection signal data (here, 10 bits) corresponding to each address is output from the memory 27, and is converted by the DA converter 39 into vertical deflection signals v and v' shown in FIG. In this circuit 240H
There is a memory address for storing the vertical deflection signal corresponding to each line of minutes, and by storing regular data in the memory every 16H minutes, it is possible to obtain a 16-step vertical deflection signal.

On the other hand, the line cathode drive circuit 26 receives the vertical synchronization signal V
and the output of the vertical deflection counter 25 to create line cathode drive pulses [I to Y]. 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 25.
FIG. 9b shows a method of creating line cathode drive pulses [A' to Y'] every 16H using these signals.
In Figure 9, LSB indicates the lowest bit, (LSB+
1) means the bit one higher than the LSB.

The first line cathode drive pulse [A'] can be created by an R-S flip-flop using the vertical synchronization signal V and the output (LSB+4) of the vertical deflection counter 25, and the line cathode drive pulse [A'~ y'] uses a shift register to transfer the line cathode drive pulse [a'] to the vertical deflection counter 25.
It can be obtained by using the inverted version of the output (LSB+1) as the clock and transferring it. These driving pulses [A' to YO'] are inverted so that the potential is low only during each pulse period, and the line cathode driving pulses [A to YO'] are set to a high potential of about 20 volts during other periods.
y] and added to each line cathode 2i to 2yo.

Each line cathode 2i~2yo has its driving pulse [i~
A current is passed through it during the high potential of drive pulses [Y] to heat it, and the heated state is maintained so that electrons can be emitted during the low potential period of the drive pulses [I to Y]. As a result, low-potential driving pulses [I to YO] were applied to each of the 15 line cathodes 2I to 2Y.
Electrons are emitted only during the 16H period. During the period when a high potential is applied, the potential at the line cathode 2 is lower than the potential at the position of the line cathode 2 determined by the bias voltage applied to the back electrode 1 and the vertical focusing electrode 3. Since the applied high potential becomes positive, no electrons are emitted from the line cathodes 2I to 2Y. Thus, in the line cathode 2, electrons are sequentially emitted from the upper line cathode 2a toward the lower line cathode 2y every 16H period during the effective vertical scanning period.

The emitted electrons are pushed forward by the back electrode 1, pass through the opposing slits 10 of the vertical focusing electrode 3, and are focused in the vertical direction to form a flat electron beam.

Next, the relationship between the line cathode drive pulses [I to Y] and the vertical deflection signals v and v' will be explained using FIG. 10. The vertical deflection signals v and v′ change by 1H during the 16H period of each line cathode pulse [I to Y], and
change in stages. The vertical deflection signals v and v' both have a center voltage of _V4 , and are configured to change in opposite directions so that v increases sequentially and v' decreases sequentially. These vertical deflection signals v and
v′ are electrodes 13 and 13′ of vertical deflection electrode 4, respectively;
As a result, each line cathode 2~
The electron beam generated from 2-Yo is vertically deflected in 16 steps, and as mentioned earlier, on the screen 9, one electron beam draws a raster of 16 lines one line at a time from the top. Deflected.

As a result of the above, an electron beam is emitted for a period of 16 hours from the top of the 15 line cathodes 2A to 2Y, and each electron beam is sequentially emitted for one line from the top to the bottom within 15 sections in the vertical direction. As a result, the electron beam is vertically deflected one line at a time on the screen 9 from the first line at the top end to the 240th line at the bottom end, thereby drawing a raster of 240 lines in total.

The vertically oriented electron beam is horizontally divided into 180 sections by the control electrode 5 and the horizontal focusing electrode 6 and extracted. Figure 5 shows one of these categories. The amount of electron beam passing through each section is controlled by a control electrode 5, and horizontally focused by a horizontal focusing electrode 6 into a single narrow electron beam, which is then controlled by horizontal deflection means described below. The light is then deflected in six steps in the horizontal direction and is sequentially irradiated onto each of the R, G, and B phosphors 20 corresponding to two picture elements on the screen 9. FIG. 10 shows the vertical and horizontal divisions. The phosphors corresponding to each of 15a to 15n of the control electrode 5 are R, G, and B for two picture elements, but for convenience of explanation, one picture element is shown here.
Let R ₁ , G ₁ , B ₁ be R ₂ , G ₂ , B ₂ .

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 6H having a repetition 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 horizontal six times pulses 6H. This horizontal deflection counter 28 is
6 times during 1H, 240H x 6/H = 1440 during 1V
The count output is supplied to an address in the memory 29. The memory 29 outputs horizontal deflection signal data (here, 8 bits) according to the address, and the D-A converter 38 converts it into horizontal deflection signals such as h and h' 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 waves are generated in 1H period. horizontal deflection signals can be obtained.

This horizontal deflection signal is a pair of horizontal deflection signals h and h' that change in six steps as shown in FIG.
Both have a center voltage of V ₇ , h gradually decreases,
h' increases in sequence and changes in opposite directions. These horizontal deflection signals h, h' are applied to electrodes 18 and 18' of the horizontal deflection electrode 7, respectively.
As a result, each horizontally divided electron beam is transmitted to the R, G, B,
It is horizontally deflected so that R, G, and B (R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , B ₂ ) phosphors are sequentially irradiated with H/6 each. Thus, in each line raster, the electron beam is divided into R ₁ , G ₁ ,
Each phosphor 20 of B ₁ , R ₂ , G ₂ , and B ₂ is sequentially irradiated with light.

Therefore, an electron beam is applied to each horizontal section of each line.
A color television image can be displayed on the screen 9 by modulating the video signals R ₁ , G ₁ , B ₁ , R _{2 ,} G ₂ , and B 2 .

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 30,
Here, the color difference signals of R-Y and B-Y 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,
B primary color signals (hereinafter referred to as R, G, and B video signals) are output. Each of these R, G, and B video signals are processed by 180 sample hold circuit sets 31a to 3.
Added to 1n. Each sample hold circuit group 3
1a to 31n are for R ₁ , G ₁ , B ₁ , R ₂ respectively
It has six sample-and-hold circuits for G, _G2 , and _B2 . These sample and hold outputs are respectively applied to holding memory sets 32a-32n.

On the other hand, the reference clock oscillator 33 is constituted by a PLL (phase locked loop) circuit, etc., and in this embodiment generates a reference clock 6 _SC that is six times as large as the color subcarrier _SC and a reference clock 2 _SC that is twice the color subcarrier SC. The reference clock is controlled to always have a constant phase with respect to the horizontal synchronizing signal H. The reference clock 2 _SC is added to the deflection pulse generation circuit 42, and a signal 6 which is six times the horizontal synchronization signal H is applied to the deflection pulse generation circuit 42.
Signal switching pulses for each H and H/6 r ₁ , g ₁ , b ₁ , r ₂ ,
Pulses of g ₂ and b ₂ are obtained. On the other hand, reference clock 6
_{The SC} is applied to the sampling pulse generation circuit 34, where it is delayed by one clock cycle by a shift register, so that the horizontal cycle (63.5 μsec)
During the effective horizontal scanning period (approximately 50μsec)
1080 sampling pulses Ra ₁ to Bn ₂ are sequentially generated, and then one transfer pulse t is generated. These sampling pulses Ra ₁ to Bn ₂ 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 synchronization signal H. controlled so that

These 1080 sampling pulses Ra ₁ to Bn ₂ are each connected to 180 sample and hold circuit sets 31a.
31n, and as a result, R ₁ , G ₁ , B ₁ , R for each two picture elements when one line is divided into 180 are added to each sample-and-hold circuit set 31a to 31n. ₂ , _G2 , and _B2 are individually sampled and held. The sample-held 180 pairs of R ₁ , G ₁ , B ₁ , R ₂ , G ₂ ,
After the sample and hold for one line is completed, the _B2 video signal is transferred all at once to 180 sets of memories 32a to 32n by a transfer pulse t, where it is held for the next horizontal period. This retained R ₁ , G ₁ ,
B ₁ , R ₂ , G ₂ , B ₂ signals are sent to the switching circuit 35
Added to a~35n. Switching circuit 35
a to 35n are R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , B ₂ respectively
It is composed of a tri-state or analog gate having individual input terminals and a common output terminal for sequentially switching and outputting these input terminals.

The output of each switching circuit 35a to 35n is
180 sets of pulse width modulation (PWM) circuits 37a to 3
7n, and here, the reference pulse signal is pulse width modulated according to the magnitude of the sampled and held R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , B ₂ video signal and is output. It is desirable that the repetition period of the reference pulse signal is sufficiently smaller than the pulse width of the signal switching pulses r ₁ , g ₁ , b ₁ , r ₂ , g ₂ , b ₂ , for example, 1:10 to 1:10. A ratio of about 1:100 is used.

The output of the pulse width modulation circuits 37a to 37n is used as a control signal for modulating the electron beam to the 180 conductive plates 15a to 15 of the control electrode 5 of the display element.
n separately. Each of the switching circuits 35a to 35n receives a switching pulse r ₁ , which is applied from the switching pulse generation circuit 36.
Switching is controlled simultaneously by g ₁ , b ₁ , r ₂ , g ₂ , and b ₂ . The switching pulse generation circuit 36 generates a signal switching pulse from the deflection pulse generation circuit 42 mentioned above.
It is controlled by r ₁ , g ₁ , b ₁ , r ₂ , g ₂ , b ₂ ,
Each horizontal period is divided into six, and the switching circuits 35a to 35n are switched by H/6, and R ₁ , G ₁ , B ₁ ,
Switching signals r _{1 ,} g ₁ , b _{1 ,} r ₂ , g _{2 ,} b Generate ₂ .

What should be noted here is that the switching circuit 3
R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , B ₂ in 5a to 35n
switching of supply of each video signal, and electron beams R ₁ , G ₁ , B ₁ , R 2 , G ₂ , B ₂ by the horizontal deflection drive circuit ₄₁
The horizontal deflection and switching of irradiation to the phosphor are synchronously controlled so that they completely match both in timing and order. This results in
When the electron beam is irradiating the R ₁ phosphor, the irradiation amount of the electron beam is controlled by the R ₁ video signal, and also for R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , and B ₂ . Similarly controlled, R ₁ , G ₁ , B ₁ ,
R ₂ , G ₂ , B ₂ The luminescence of each phosphor is R ₁ ,
Each picture element is controlled by the video signals of G ₁ , B ₁ , R ₂ , G ₂ , and B ₂ , and each picture element is displayed by emitting light according to the input video signal. Such control is performed simultaneously for 180 sets (2 pixels each) for one line, so that an image of 360 pixels per line is displayed, and then sequentially for 240 minutes from the upper line to display the image on the screen 9. One image will be displayed.

The above operations are repeated for each field of the input television signal, and as a result,
The screen 9 is similar to a normal television receiver.
The television footage of the video is shown above.

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 the positional deviation in the vertical direction will occur if the raster interval is shortened. This appears as an increase or decrease in brightness due to

Such deviations in the landing position of the electron beam are thought to be caused by changes in the vertical deflection waveform over time or the expansion and contraction of the electrodes that make up the display element over time. In order to maintain this, it is necessary to make the deflection waveform amplification circuit extremely precise and to use electrode materials that have very little expansion and contraction, which lead to increased power consumption and cost. Therefore, it is not practical.

Means for Solving the Problems In the present invention, the vertical landing position of the electron beam irradiated onto the screen, the electrode located outside the effective screen of at least one of the electrodes arranged closer to the screen than the vertical deflection electrode. The signal from the resistor when the electron beam is irradiated to the correct position on the screen is stored in a memory circuit, and the signal from the resistor is detected during actual operation. The signal stored in the memory circuit is compared with the signal stored in the memory circuit, and the difference is fed back to a part of the display element drive circuit.

Effects According to the image display device of the present invention, the landing position of the electron beam irradiated onto the screen in the vertical direction is detected, and the signal from the resistor during actual operation and the signal stored in the memory circuit are detected. Compared to,
By feeding back the difference to a part of the display element drive circuit, it is possible to always maintain the vertical landing position of the electron beam at the normal position.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1a, a vertical focusing electrode 3' is arranged on the screen side of the vertical deflection electrode 4 of the display element.
A vertically long resistor 50 is arranged outside the effective screen on the vertical deflection electrode side so as to be sandwiched between a pair of vertical deflection electrodes 4. This resistor 50
is formed on an insulator 51 made of ceramic, for example, and is fixed by adhering this insulator 51 to the vertical focusing electrode 3'. The lead wires 53 of each are pulled out. Then, the pilot electron beam 52 for detecting the landing position of the electron beam is vertically deflected so as to irradiate one point each near the upper end and the lower end of the resistor 50 during the vertical retrace period.

Specifically, as shown in FIG. 3, for example, in addition to the period in which an image is displayed in the n-th vertical segment K _o , the line cathode drive pulse is used to display K _o during the vertical retrace period of each field. Correspondingly, the vertical deflection waveform is set such that the electron beam irradiates the vicinity of the upper end of _Ko during the vertical retrace period of the mth field, and irradiates the vicinity of the lower end of _Ko during the vertical retrace period of the m+1 field. The driving waveform may be such that an electron beam is irradiated.

As shown in FIG. 1b, the beam electrons irradiated onto the resistor 50 flow in inverse proportion to the respective resistance values from the incident position 54 to the lead wire extraction points 55, 55', and a current I ₁ , _I2 .
To convert these current signals into electron beam incident position signals, I ₁ and I ₂ are connected to a current-voltage conversion circuit 56,
After converting into voltages E ₁ and E ₂ at 56′, (E ₁ − E ₂ )/
It is sufficient to perform the calculation (E ₁ +E ₂ ), and by this calculation, a position signal that is not affected by an increase or decrease in the irradiation amount of the electron beam can be obtained.

Now, a feedback system for compensating the landing position of the electron beam can be constructed as shown in FIG.

The pulse signals E ₁ and E ₂ obtained by the current-voltage conversion circuits 56 and 56' are sampled and held by the circuits 57 and 57', and then time-divided by the A/D converter 58.
The data is AD converted and stored in the memory 60 via the CPU 59. This stored data is converted into position data by the calculation of the CPU, and is compared with initial position data in the memory 60, which has been previously stored in a similar manner at the time of optimal adjustment of the landing position. If the position data D2 of the electron beam irradiated on the upper end of K _o and the position data D3 of the electron beam irradiated on the lower end are the respective initial position data D
0, D1, if D2>D0 and D3>D1 or D2<D0 and D3<D1, it is determined that the entire K _o has changed up and down as shown in Figure 4a,
Also, D2>D0 and D3>D1 or D2<D0 and D3
If <D1, it is determined that the amplitude of K _o has expanded or contracted as shown in FIG. 4b.

Then, depending on each case, the data difference is appropriately added or subtracted from the vertical deflection data for K _o stored in the deflection data memory 27, so that D2=D0 and D3=D1. Feedback will be provided.

As described above, the vertical irradiation position of the electron beam can be controlled so as to always be 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 a resistor placed inside the display element, and the electron beam is positioned at the normal position on the screen. By comparing the signal from the resistor stored in the memory circuit when irradiated with the signal from the resistor during actual operation, and feeding the difference back to a part of the display element drive circuit, This is to control the electron beam so that it is irradiated at the correct position on the screen, and it is used to control the vertical electron beams that occur due to changes in the characteristics of the drive circuit over time or the expansion and contraction of the electrodes that make up the display element over time. It is possible to compensate for changes in the landing position of the beam and keep the vertical raster spacing constant to prevent uneven brightness.

[Brief explanation of the drawing]

1a and 1b are enlarged exploded perspective views and front views showing the arrangement and detection principle of the electron beam position detection resistor of an image display element used in the image display device of the present invention, and FIG. 2 is the feed thereof. A block diagram showing the configuration of the back system. Figure 3 is a waveform diagram showing the vertical deflection waveform and line cathode driving pulse waveform for irradiating the pilot electron beam. Figure 4 explains the vertical change in the electron beam position. 5 is an exploded perspective view of an image display element used in a conventional image display device, FIG. 6 is an enlarged front view of the fluorescent surface of the image display element, and FIG. 7 is an image thereof. A block diagram showing the basic configuration of the display element drive circuit, FIG. 8 is a waveform diagram for explaining the operation of the vertical deflection drive, FIG. 9 is a waveform diagram for explaining the operation of the line cathode drive circuit, and FIG. The figure is a waveform diagram of each drive signal, and FIG. 11 is a waveform diagram for explaining the operation of the horizontal deflection drive circuit. 2, 2 I to 2 Y... Line cathode, 3, 3'... Vertical focusing electrode, 4... Vertical deflection electrode, 5... Beam flow control electrode, 7... Horizontal deflection electrode, 9... Screen, 10 ...slit, 20...fluorescent material, 23...
...Input terminal, 24...Synchronization separation circuit, 25...Vertical deflection counter, 26... Line cathode drive circuit,
27...Memory, 28...Horizontal deflection counter, 29...Memory, 30...Color demodulation circuit, 31
a~31n...sample hold circuit, 32a~
32n...Memory, 33...Reference clock oscillator, 34...Sampling pulse generation circuit, 35
a to 35n... Switching circuit, 36... Switching pulse generation circuit, 37a to 37n...
PWM circuit, 38...D/A converter, 39...
D/A converter, 40... Vertical deflection drive circuit, 41
... Horizontal deflection drive circuit, 42 ... Deflection pulse generation circuit, 50 ... Electron beam position detection resistor, 5
1... Insulator, 56, 56'... Current-voltage conversion circuit, 57, 57'... Sample hold circuit,
58...A/D converter, 59...CPU, 60...
…memory.

Claims (1)

[Claims] 1 a plurality of line cathodes that generate electron beams, a focusing electrode that focuses the electron beam generated from the line cathode, a vertical deflection electrode that electrostatically deflects the electron beam focused by the focusing electrode in the vertical direction; a control electrode that controls the amount of the electron beam deflected in the vertical direction by the vertical deflection electrode; a horizontal deflection electrode that deflects the electron beam controlled by the control electrode in the horizontal direction; and the electrons deflected by the horizontal deflection electrode. In an image display device comprising a screen having a phosphor that emits light when irradiated with a beam, an area outside an area corresponding to an effective screen of at least one electrode among the electrodes arranged closer to the screen than the vertical deflection electrode. an electron beam position detection means consisting of at least one resistor disposed in the screen and electrically isolated from the electrode; and control means for comparing the signal from the resistor during operation and feeding back the difference to a part of the display element drive circuit to control the electron beam to be irradiated to a proper position on the screen. Characteristic image display device.