JPS63254880A - Picture display device - Google Patents

Abstract

PURPOSE:To easily compensate a brightness on an arbitrary area on a screen by adding a circuit for modulating the luminance signal level of a video signal outputted from a chrominance demodulating circuit by defining one field to be a cycle. CONSTITUTION:In a picture display device constituting of N line cathodes 2, the respective line cathodes K1-KN are simultaneously sequentially driven in the one field and an electron beam is discharged. For instance, when the brightness of the area (area of slash) on the screen assigned to the line cathode K2 is low, the line cathode K2 operates to a t2 time after t1 time elapses from a vertical synchronizing signal 56. Accordingly, only during the period of t1-t2, data (c) for modulating the luminance signal level is read from a memory 52 through a brightness modulating counter 51, converted to an analog signal in a D/A converter 53, applied to the output of the chrominance demodulating circuit 30, thereby, the luminance level is raised to compensate the brightness.

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, a new display device was proposed in Japanese Patent Application Laid-Open No. 135590/1983, which uses electron beams to achieve a flat 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 a 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 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 pulp (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 wires, 2i to 22 are shown) are provided. In this embodiment, it is assumed that 16 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 having a diameter of 0 to 2 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 is
It acts to suppress 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 to push out the generated electron beams only in the forward direction. . 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. Further, instead of the back electrode 1 and 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 (360 pixels) are taken out 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 a row of through holes provided horizontally at small intervals (so that they almost touch each other). Alternatively, it may be configured as a slit. The vertical focusing electrode 2 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 conductors 13 and 13' provided on the upper and lower surfaces of the insulating substrate 12. has been done. Then, a vertical deflection voltage is applied between the opposing conductors 13 and 13',
Deflect the electron beam vertically. In this embodiment, the electron beam from one line cathode 2 is vertically deflected to a position corresponding to 16 lines by a pair of conductors 13, 13'.

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 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 6 extracts the electron beam horizontally by dividing it into two picture elements each, and controls the amount of electron beam passing therethrough in accordance with the video signal for displaying each picture element.

Therefore, the conductive plates 15a to 15n for the control electrode 6 are
If 0 lines 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 sets of video signals for one line (2 pixels per set) are simultaneously applied to each of the 180 conductive plates 15a to 16n for the control electrode 6, and 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 5, and collects electrons for each pixel 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.
Accelerate the electron beam so that it hits the screen with sufficient energy.

The screen 9 is constructed by applying a phosphor 2o 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 2o are provided with two pairs of phosphors of three colors R9G 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 the enlarged view in Figure 4, one section partitioned by these two has two R, G, and H phosphors for two picture elements in the horizontal direction.
o, and has a width of 162 inches in the vertical direction. For example, the size of one section is 1 a in the horizontal direction.
, the vertical direction is 10fl.

Note that in FIG. 3, the length in the horizontal direction is greatly expanded relative to the length in the vertical direction for clarity.

In addition, in this embodiment, only one pair of R, G, and B phosphors 20 are provided for one control electrode 6, that is, for one electron beam, for two picture elements, but of course, one picture element The control electrode 6 may be provided with R, G, B for one picture element or three picture elements or more.
Video signals are applied sequentially, and horizontal deflection is performed in synchronization with the video signals.

Next, the basic configuration of a drive circuit for displaying television images on this display element will be described with reference to FIG. 5. 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. v3・, 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 4o includes a vertical deflection counter 26.
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 synchronization signal V and a horizontal synchronization signal H shown in FIG. 6 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 26 is counted during an effective scanning period (in this case, 24
This count output is supplied to the address of the memory 27. Vertical deflection signal data (here, 10 bits) corresponding to each address is output from the memory 27, and the data is converted to V as shown in FIG. 6 by the DA converter 39.

V' is converted into a vertical deflection signal. In this circuit, 24O
There is a memory address for storing a vertical deflection signal corresponding to each line of H minutes, and by storing regular data in the memory every 16H minutes, a 16-step vertical deflection signal 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 25 to create line cathode drive pulses [I to YO]. FIG. 7a shows the relationship between the vertical synchronizing signal (2), the horizontal synchronizing signal H, and the lower six bits of the vertical deflection counter 26. Figure 7 shows 16 using each of these signals.
A method of creating line cathode drive pulses [I' to B] for each H will be shown. In FIG. 7, 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 using an R-S 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'] are transferred by using a shift register to transfer the line cathode drive pulse [A'] using the inverted version of the output (LSB+3) of the vertical deflection counter 26 as a clock. Obtainable. This drive pulse [A' to Yo'] is inverted and converted into a line cathode drive pulse [I to Yo], which has a low potential only during each pulse period, and a high potential of about 20 volts during other periods. , are added to each line cathode 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 can be 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 16H 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 2 to the lower line cathode 2 every 1 eH 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 [I to Y] and the vertical deflection signal v
, v' will be explained using FIG.

The vertical deflection signals v and v' are each line cathode pulse [I to Y]
During the 16H period, it changes by 1H and changes in 16 steps. The center voltage of both vertical deflection signals V and V' is v4.
They are designed to change in opposite directions, such that {circle around (2)} increases sequentially and V' 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 deflected in 16 steps in the vertical direction. As described above, on the screen 9, one electron beam is deflected so as to sequentially draw 16 lines of rascous one line at a time from the top.

As a result of the above, electron beams are emitted for each 16H period from the top of the 16 line cathodes 2I to 2Y, and each electron beam is sequentially emitted for one line from top to 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 divided into 180 sections by the control electrode 6 and the horizontal focusing electrode 6 and extracted. Figure 3 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 the R, G, and B6 phosphors 20 corresponding to two picture elements on the screen 9. FIG. 4 shows the vertical and horizontal divisions. Control electrodes 6 15a to 15, respectively
The phosphor corresponding to m is R, G, 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 manual pulse of the horizontal deflection drive circuit 41 is synchronized with the vertical synchronizing signal V and the horizontal synchronizing signal H, as shown in FIG. 9, 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 (2) and counts the horizontal six times pulse 6H. This horizontal deflection counter 28 counts 6 times during 1H and 240H×6/H=1440 times during 1V, and this count output is supplied to the address of the memory 29. From the memory 29, horizontal deflection signal data (
Here, 8 bits) are output, and the D-A converter 38 outputs the
It is converted 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 horizontal waves are generated in 1H period. A deflection signal can be obtained.

As shown in FIG. 9, this horizontal deflection signal is a pair of horizontal deflection signals ri and h' that change in stages e, both of which have a center voltage of v7, h decreasing sequentially and h' increasing sequentially. They change in opposite directions as they move forward. These horizontal deflection signals h and h' are applied to the electrode 18 of the horizontal deflection electrode 7, respectively.
and 18'.

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

It is horizontally deflected so that the phosphors of G and B (R1, G1.B1.R2, G2.B2) are sequentially irradiated with H/e.

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 20 of B2 is sequentially irradiated with light.

Therefore, the electron beam is set to 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. Those R, G, and B6 video signals are processed by 180 sample and hold circuit sets 31a to 31.
Added to H. Each sample and hold circuit set 31a to 3
1n is for R1, G1, B1; R2.

It has six sample and hold circuits for 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 (needs-locked loop) circuit, etc., and in this embodiment, the reference clock 6fsa, which is six times the color subcarrier fsc, is used.
and generates a double reference clock 2f80. The reference clock is controlled to always have a constant phase with respect to the horizontal synchronizing signal H. A reference clock 21110 is added to the deflection pulse generation circuit 42, and a signal 6H, which is six times the horizontal synchronization signal H, and a signal switching pulse r1. g1.
b1. r2゜q2# B2 pulse is obtained. On the other hand, the reference clock 6f. is sampling pulse generation circuit 3
4, and is then delayed by one clock period by a shift register, so that the horizontal period (63,5μ5
ec), 1080 sampling pulses R&1 to Bn2 are sequentially generated during the effective horizontal scanning period (approximately 50 μ5 ec), and then one transfer pulse t is generated. 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~B! 12
are each 180 sample and hold circuit sets 31a~
31n, and as a result, each sample-and-hold circuit set 31a to 31n has R1, G1 . B1
．． R2, G2. Each video signal of B2 is individually sampled and held.

The sample held 180 pairs of R1, G1゜B
1. R2, G2. After completing the sample and hold for one line, 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 R1. G1. B
1. R2, G2. The signal of B2 is the switching circuit 36
Added to a~35n. Switching circuits 35a-3
5n are R1°G, , B1 . R2, G2. B2
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 36&~35n is applied to 180 sets of pulse width modulation (PWM) circuits 37a~37n, where R1. G1. B1.
R2, G2. The reference pulse signal is pulse width modulated according to the magnitude of the B2 video signal and output. The repetition period of the reference pulse signal is the signal switching pulse r1. q1
．． b1. r2. It is desirable that the pulse width of G2°B2 is sufficiently smaller, for example, 1:10 to 1:
About 100 are used.

The outputs of the pulse width modulation circuits 37a-37n are individually applied to the 180 conductive plates IE5a-15n of the control electrode 6 of the display element as control signals for modulating the electron beam. Each of the switching circuits 36a to 35n receives a switching pulse τ1.tau applied from the switching pulse generation circuit 36. (il, blj r2jq2.B2
Switching is controlled at the same time. The switching pulse generation circuit 36 receives signal switching pulses r1 #q1. from the aforementioned deflection pulse generation circuit 42. b1t r2. G2,1
)2, each horizontal period is divided into six, and the switching circuits 35a to 35n are switched by H/6, and the switching circuits 35a to 35n are controlled by R1°G1. B1. R2, G2. Each video signal of B2 is time-divided and sequentially outputted to the pulse width modulation circuit 37a.
-37n, the switching signal r1. q1. b1.
r2. Generates b2°G2.

What should be noted here is that the switching circuits 35a to 3
R1 in 6n. G1. B1. R2, G2°B2 video signal supply switching and electron beam R1, 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 R1 video signal, and the G1. B1. R2, G2. B
2 are similarly controlled, and R1, G1 .
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 video signal of B2, 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, and 2
One video is displayed on the screen 9 by sequentially performing the 40-minute lines starting from the upper line.

The above operations are performed on one input television signal.
This is repeated field by field, and as a result, a moving television image is displayed on the screen 9, similar to a normal television receiver.
/The image is projected.

Problems to be Solved by the Invention Since this image display device is constructed from a plurality of line cathodes and electrodes, brightness unevenness may occur on the screen due to subtle differences in the characteristics of the line cathodes, distortion of the focusing electrode, etc. may occur. There is no suitable compensation method for this brightness unevenness, and it has been dealt with by subtly changing the beam position during adjustment.

However, in the compensation for brightness unevenness during the above adjustment,
0 Beams at arbitrary positions on the screen cannot be moved individually (beams that share a common deflection electrode and are displayed at the same time will all move). ■It had problems such as the inability to change the brightness of the beam.

In view of the above problems, the present invention provides an image display device that makes it possible to compensate for uneven brightness by changing the brightness of any position or area on the screen.

Means for Solving the Problems In order to solve the above problems, the image display device of the present invention includes:
A circuit is added that modulates the luminance signal level of the video signal output from the color demodulation circuit at a period of one field.

For production The effect of this technical means is as follows.

On a television screen based on the NTSC system, scanning lines are formed by video signals sequentially from the top left on the screen based on a vertical synchronization signal, and one field is formed between them until the next vertical synchronization signal. At this time, the timing from the vertical synchronization signal and the position of the beam on the screen at that time are uniquely determined. Therefore, a counter that is reset by the vertical synchronization signal is provided,
When the memory address is changed at small time intervals and the memory is read, the digital data in each memory address is
Indicates the amount by which the luminance signal level should be changed to a fixed position on the screen. Therefore, always use this data as D/A.
By adding it to the video signal via a converter, it is possible to compensate for the brightness on the screen.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention.
is a brightness modulation counter that is reset by the vertical synchronization signal V, and reads the modulation data in the memory 62 while changing the address every time the vertical synchronization signal V is input manually. 63 is a DA converter that converts this modulation data into an analog signal. The other configurations are the same as those shown in the prior art, so explanations will be omitted.

The operation will be described with reference to FIG. 2, taking as an example a case where different brightness is compensated for each line cathode 2. In an image display device constituted by N line cathodes 2 as shown in FIG. 2(a), each line cathode 2 is sequentially driven during one field to emit an electron beam, as shown in the middle of the figure. According to the above example, each line cathode emits electrons every 16H period. Now, suppose that the brightness of the area on the screen that the line cathode 2 is responsible for (the shaded area in the figure) is dark, then the line cathode 2 is operating as shown in Figure 2 (03). , 11 hours after the vertical synchronization signal 66 and up to 12 hours. Therefore, only during the period t1 to t2, the data (C) for modulating the luminance signal level is read from the memory 62, converted to an analog signal, and added to the output of the color demodulation circuit 3o to increase the luminance signal level. Brightness compensation can be performed.

Effects of the Invention As described above, according to the present invention, since brightness compensation is performed at the stage of the brightness signal, brightness compensation for any area on the screen can be easily performed, and brightness unevenness can be eliminated. It is possible to obtain high-quality images without any interference.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an image display device according to an embodiment of the present invention, Fig. 2 a, b, and c are line cathode arrangement diagrams and waveform diagrams for explaining its operation, and Fig. 3 is an image display of a conventional example. FIG. 4 is an exploded perspective view of the image display element used in the device; FIG. 4 is an enlarged front view of the fluorescent surface of the image display element; FIG. 6 is a block diagram showing the basic configuration of the drive circuit of the image display element; The figure is a waveform diagram to explain the operation of vertical deflection drive, Figure 7 a, b
Figure 8a is a waveform diagram for explaining the operation of the line cathode drive circuit.
, b, and c are waveform diagrams of each drive signal, and FIG. 9 is a waveform diagram for explaining the operation of the horizontal deflection drive circuit. 2... Line cathode, 3... Vertical focusing electrode,
4... Vertical deflection electrode, 6... Beam flow control electrode, 7... Horizontal deflection electrode, 9...
・Screen, 61... Brightness modulation counter,
62...Memory, 63...D, /A converter. Name of agent: Patent attorney Toshio Nakao and one other person: Ren
TV screen (a) (Muhdah (C Noie Screen 20- ψ light body Figure 4 Ice square phrase 01 division: jS6 Figure Knee) Figure 7

Claims (2)

[Claims] (1) A plurality of line cathodes constituting an electron beam source, a focusing electrode that focuses the electron beam from the line cathode, and a deflection electrode that deflects the electron beam in vertical and horizontal directions, and the electron beam is irradiated. and an electron beam control electrode that controls the amount of the electron beam according to a television signal and controls the brightness on the screen, and the brightness signal level of the television signal is controlled at a period of one field. An image display device characterized in that brightness is adjusted by changing. (2) The amount of compensation for the luminance signal level is stored in the memory as digital data, and the digital data is read out at the timing of a counter reset by a vertical synchronization signal, and superimposed on the luminance signal via a D/A converter. An image display device according to claim 1, characterized in that: