JPH0341000B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a flat image display device, and more particularly to a means for correcting changes over time, temperature changes, AC input voltage fluctuations, etc.

Conventional configurations and their problems Traditionally, cathode ray tubes have been mainly used as display elements for displaying color television images, but conventional cathode ray tubes are extremely long and thin compared to the screen size. It was impossible to create a full-sized television receiver. In addition, EL display elements, plasma display devices, 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, and have not yet been put into practical use.

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. 135590/1983) 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). 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, Only four (2A to 2D are shown) are provided. In this embodiment, it is assumed that 15 pieces are provided. Let these be 2i to 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. 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 will be described later, the electron beams are generated sequentially for a certain period of time starting from the line cathode 2I. controlled to emit. The back electrode 1 suppresses generation of electron beams from line cathodes 2 other than the line cathode 2 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. 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. Also, instead of these back electrode 1 and line cathode 2,
A planar electron beam emitting cathode may also be used.

The vertical focusing electrode 3 is a conductive plate 11 having a horizontally long slit 10 facing each of the line cathodes 2I to 2Y, and extracts the electron beam emitted from the line cathode 2 through the slit 10, and focus in a direction. An electron beam for one horizontal line (360 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. 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 are each composed of conductive pairs 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, a pair of conductors 13, 13 deflects 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 15 pairs of conductors corresponding to each of the 15 line cathodes 2, and in the end, the electron beams are drawn so as to draw 240 horizontal lines on the screen 9. to deflect.

Next, the control electrodes 5 are composed of conductive plates 15 each having a vertically long slit 14, and a plurality of control electrodes 15 are arranged in parallel in the horizontal direction 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 extracts the electron beam by dividing it into two picture elements in the horizontal direction, and controls the amount of the 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 with 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 composed of a plurality of conductive plates 18, 18' arranged vertically on both sides of the slit 16, and each electrode 18, 18 is provided with six levels of horizontal deflection voltage. is applied to horizontally deflect the electron beam for each picture element, and on the screen 9, two sets of R, G,
Each of the phosphors B is 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 applying a phosphor 20 that emits light when irradiated with an electron beam to the back surface of a terrace plate 21, 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 of phosphors in each of the three colors R, G, and B are provided, and are applied in stripes in the vertical direction. In FIG. 1, the broken lines drawn on the screen 9 indicate divisions in the vertical direction corresponding to each of the plurality of line cathodes 2, and the two-dot chain lines indicate the divisions in the vertical direction corresponding to each of the plurality of control electrodes 5. Indicates the displayed horizontal division. 1 divided by these two
As shown in an enlarged view in Figure 2, each section has R, G, and B phosphors 20 for two picture elements in the horizontal direction, and has a width for 16 lines in the vertical direction. . The size of one section is, for example, 1 mm in the horizontal direction and 9 mm in the vertical direction.

Note that in FIG. 1, the length in the horizontal direction is greatly enlarged relative to the length in the vertical direction for clarity.

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. In this 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 in synchronization with this, horizontal deflection is performed. 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. 4 are used. The vertical deflection counter 25 (8 bits) receives the vertical synchronization signal V.
The horizontal synchronizing signal H is counted. 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. The memory 27 outputs vertical deflection signal data (here, 10 bits) corresponding to each address, and the D-A converter 39 outputs the data of the vertical deflection signal as shown in FIG.
It is converted into a vertical deflection signal of V′. In this circuit
There is a memory address that stores the vertical deflection signal corresponding to each line of 240H, and by storing regular data in the memory every 16H, it is possible to obtain 16 levels of vertical deflection signals.

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. 5a 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. 5b shows a method of creating line cathode driving pulses [A' to Y'] every 16H using these signals. In Figure 5, 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+3) 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~
During the high potential period of drive pulses [Y], a current is passed and heated, and the heated state is maintained so that electrons can be emitted during the low potential period of the drive pulses [Y]. As a result, a low potential drive pulse [I to YO] is applied to each of the 15 line cathodes 2I to 2Y at 16H.
Electrons are released only during this 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 2yo. 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. 6. The vertical deflection signals V, V' change by 1H during the 16H period of each line cathode pulse [I to Y], and change in 16 steps. The vertical deflection signals V and V′ both have a center voltage of V ₄ , and V increases sequentially,
V′ is configured to change in opposite directions so as to decrease sequentially. These vertical deflection signals V and V' are applied to the electrode 13 of the vertical deflection electrode 4, respectively.
and 13', and as a result, the electron beams generated from each of the line cathodes 2i to 2yo are vertically deflected in 16 steps, and as mentioned earlier, one electron beam is reflected on the screen 9. The raster is deflected to draw 16 lines of raster one line at a time, starting from the top.

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 electron beam thus vertically deflected is horizontally deflected by 180 degrees by the control electrode 5 and the horizontal focusing electrode 6.
It is divided into sections and taken out. Figure 1 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. 2 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. Horizontal deflection signal data (here, 8 bits) corresponding to the address is output from the memory 29, and converted by the D-A converter 38 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 6 steps as shown in FIG. 7, both have a center voltage of V ₇ , and 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 R ₁ ,
Each phosphor 20 of G ₁ , 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. Furthermore, each of the R, G, and B video signals are processed by 180 sample and hold circuit sets 31a~
31n. Each sample and hold circuit set 31a to 31n is for _R1 , _G1 , _B1 ,
It has six sample and hold circuits for R ₂ , G ₂ , and B ₂ . 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 generates a signal 6H which is six times the horizontal synchronizing signal H and signal switching pulses r ₁ , g ₁ , b ₁ , r ₂ , g ₂ , b every H/6. I'm getting ₂ pulses. On the other hand, the reference clock 6 _SC is applied to the sampling pulse generation circuit 34, where it is delayed by one clock cycle by a shift register, and is delayed for an effective horizontal scanning period (approximately 50 μsec) of the horizontal period (63.5 μsec). 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 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 sampled and held 180 pairs of R ₁ , G ₁ , B ₁ , R ₂ ,
After the video signals G ₂ and B ₂ are sampled and held for one line, they are transferred all at once to 180 sets of memories 32a to 32n by a transfer pulse t, where they are held for the next horizontal period. This retained R ₁ ,
The signals G ₁ , B ₁ , R ₂ , G ₂ , and B ₂ are applied to switching circuits 35a to 35n. The switching circuits 35a to 35n each have R ₁ , G ₁ , B ₁ , R ₂ ,
It is composed of a tri-state or analog gate having individual input terminals for G ₂ and B ₂ and a common output terminal that sequentially switches and outputs them.

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 6 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
video signal supply switching and horizontal deflection drive circuit 4
The horizontal deflection of the electron beams R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , B ₂ irradiated onto the phosphor by 1 is simultaneously controlled so that they completely match both in timing and order. It is that you are. As a result, 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 R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , B ₂ is controlled in the same way, and R ₁ , G ₁ , B ₁ , R ₂ ,
G ₂ , B ₂ The luminescence of each phosphor is R ₁ , G ₁ ,
Each picture element is controlled by the video signals of 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 1
This is done simultaneously for 180 lines (2 pixels each), and an image of 360 pixels per line is displayed.
Furthermore, the processing is performed sequentially for 240 minutes of lines starting from the upper line, and one image is displayed on the screen 9.

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.

However, in the above-mentioned image display device, each beam landing position within each vertical section is strictly determined, and it goes without saying that deviation of the beam in the horizontal direction must not occur because it impairs color reproducibility. However, if the beams shift in the vertical direction, that is, if the beam intervals in the vertical direction are no longer evenly spaced, a difference in brightness appears, which significantly deteriorates the image quality. In particular, in order to maintain equal vertical beam spacing near the boundaries of each vertical section on the screen, the accuracy of each electrode voltage and deflection waveform becomes more demanding. If the voltage applied to each electrode is stabilized and a highly accurate amplifier is used to amplify the deflection waveform, the power consumption and cost will increase, which is impractical.

Purpose of the Invention The present invention solves the above-mentioned problems of the prior art. An object of the present invention is to provide an image display device that can detect a shift and automatically correct a landing position.

Structure of the Invention An image display device according to the present invention includes a beam deflection amount detection electrode and a control circuit that controls the beam deflection amount using the detection output, so that even if the beam landing position deviates, it is automatically corrected to the correct position. This is what I did.

In order to achieve the above object, the present invention uses an anode (metal back) on the back side of the phosphor as a beam deflection detection electrode in two types: a vertical stripe (hereinafter referred to as an "H anode") and a horizontal stripe (hereinafter referred to as a "V anode").
The H anode and V anode are separated by an insulating layer, and the beam spot is arranged between each stripe.

The control circuit that controls the amount of beam deflection includes: () an amplifier circuit that converts and amplifies the deflection amount detection output current into a voltage; an A/D converter that converts the output of the amplifier circuit into digital data; and an A/D converter that converts the output of the amplifier circuit into digital data; It consists of a microcomputer for calculating increases and decreases and rewriting data in the memory 27 using the results.

Alternatively, () it is composed of an amplifier circuit that voltage converts and amplifies the deflection amount detection output current, and a control circuit that uses the output of the amplifier circuit to control the electrode voltage that affects horizontal and vertical deflection sensitivity.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 8 shows the configuration of a horizontal anode (H anode) and a vertical anode (V anode) of an image display device in an embodiment of the present invention.

In FIG. 8, 50a and 50b are H anodes, 5
1a and 51b are V anodes, 52 is an insulating layer, 53 is a fluorescent material, and 54 is each beam spot. V anode 5
1a, 51b, H anodes 50a, 50b are made by aluminum vapor deposition, V anodes 51a,
The number of stripes for 51b is the number of beam spots in the vertical direction on the screen (= number of scanning lines 480) + 1,
The number of stripes of the H anodes 50a and 50b is the number of horizontal beam spots on the screen (=600) + 1
It's a book.

In order to independently detect positional deviations in the vertical and horizontal directions, the sum of the currents flowing through each anode requires at least three anodes at the spot position, and in this example, the odd-numbered H anode ( _H1 anode below)
50a, even numbered H anode (hereinafter referred to as _H2 anode) 50
b, odd-numbered V anode (hereinafter referred to as V ₁ anode) 51a,
Among the even-numbered V anodes (hereinafter referred to as _V2 anodes) 51b,
Three anodes, an H ₁ anode, a V ₁ anode, and a combination of an H ₂ anode and a V ₂ anode (hereinafter referred to as HV anode), are used as the beam deflection amount detection electrodes.

In FIG. 9, 55 is a current-voltage converter, 56 is an amplifier, 57 is an A/D converter, and 58 is a device for calculating an increase/decrease in the deflection amount and using the results to rewrite the deflection data in the memories 27 and 29. It is a microcomputer.

The operation of the image display device configured as described above will be described below. The total current of the three anodes changes depending on the image signal, but when the beam spot shifts upward from the position shown in FIG. 8, the _V1 anode current increases, and when it shifts downward, the _V1 anode current decreases. In addition, when shifted to the left or right, the H ₁ anode current increases or decreases in the same way. However, a deviation of more than one spot cannot be detected.

The currents of the three anodes are converted into voltage by a current-voltage converter 55 using a photointerrupter or the like, and an amplifier 56 converts the currents into voltages based on the ratio of the currents of the H ₁ anode and V ₁ anode to the total beam current. The amount of positional deviation of the beam spot is output, converted into a digital signal by the A/D converter 57, and the corresponding deflection data in the memories 27 and 29 is transferred to the _H1 anode and _V2 anode by the microcomputer 58. The current ratio is rewritten in a direction that returns it to its initial value, and as a result, the spot position is corrected to the correct position.

According to this embodiment, aging, temperature change, AC
Even if the electron beam spot position shifts due to voltage fluctuations, etc., by rewriting the contents of the corresponding deflection amount, the electron beam spot is corrected to the correct position, so deterioration in image quality can be suppressed.

FIG. 10 shows the configuration of three anodes for detecting the amount of beam deflection in an image display device according to another embodiment of the present invention.

In this embodiment, a phosphor is used as an insulating layer separating the H anodes 50a, 50b and the V anodes 51a, 51b. 3 As an anode,
A V ₁ anode, a V ₂ anode, and an H anode that is tangent to the H ₁ and H ₂ anodes are used.

Effects of the Invention As described above, according to the present invention, it is possible to prevent image quality deterioration by automatically correcting beam landing position deviations caused by changes over time, temperature changes, AC voltage fluctuations, etc. and returning to the correct landing position. can get.

[Brief explanation of the drawing]

FIG. 1 is an electrode configuration diagram of an image display device to which the present invention is applied, FIG. 2 is a configuration diagram of a unit pixel on a phosphor surface of the same device, and FIG. 3 is a block diagram of a drive circuit in the same device. Figure 4 is a waveform diagram of the vertical deflection signal, Figures 5a and b are timing charts for explaining the operation, Figure 6 is a waveform correlation diagram of each signal, Figure 7 is a waveform diagram of the horizontal deflection signal, and Figure 8 The figure is a configuration diagram of a detection electrode section of an image display device according to an embodiment of the present invention, FIG. 9 is a circuit diagram of a control circuit system in the same device, and FIG. 10 is a detection electrode section showing another embodiment of the present invention. FIG. 2, 2 I to 2 Y... Line cathode, 4... Vertical deflection electrode, 5... Beam flow control electrode, 7... Horizontal deflection electrode, 9... Screen plate, 10... Slit, 2
0... Fluorescent body, 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, 31a-31n...Sample hold circuit, 32a-32n...Memory, 33...
Reference clock oscillator, 34...Sampling pulse generation circuit, 35a-35n...Switching circuit, 36...Switching pulse generation circuit, 37
a 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 , 44 I to 44 Y...Switching circuit, 50a...H ₁ anode, 50b...H ₂
Anode, 51a...V ₁ anode, 51b...V ₂ anode,
52... Insulating layer, 53... Fluorescent material, 54... Beam spot position, 55... Current voltage converter, 56
...Amplifier, 57...A/D converter, 58...Microcomputer.

Claims (1)

[Claims] 1. A screen surface divided into a plurality of sections in the vertical and horizontal directions, and means for generating an electron beam in each of the divided sections of the screen surface;
An image display device comprising vertical deflection electrodes and horizontal deflection electrodes, and means for deflecting electron beams in vertical and horizontal directions for each section of the screen surface, the image display device comprising: an insulating layer on the back surface of the screen surface; A beam deflection detection electrode that detects and outputs the deflection amount of the electron beam and inputs the detection output of the deflection amount. and above vertical,
An image display device comprising a deflection amount control circuit that controls the deflection amount of an electron beam for each section of the screen surface by controlling a voltage applied to a horizontal deflection electrode.