JPS62185477A - Picture display device - Google Patents

Abstract

PURPOSE:To constantly supply a suitable reference value and to reduce the irregular brightness on the entire of a picture by providing a function for constantly detecting and supplying the reference value of a feedback loop for controlling an electronic beam source and making the brightness constant. CONSTITUTION:Using a vertical section of the lowest brightness as a reference, other verticals sections follow thereto and the brightness of the entire picture is always uniformalized. A detection output signal from a detection resistance 51 is applied to a peak hold circuit 55 during a period except a vertical blanking and the peak value thereof is detected. During the vertical blanking period, the influence thereof is removed by a low direct current voltage value from a voltage source 54. Then, a peak value signal is supplied to a differential amplifier 56 as a reference value of the feed back loop, the difference from the detection signal supplied from a differential amplifier 52 is detected to be a compensation signal for controlling voltage sources 58, 59 every vertical section in the feedback loop. Thereby, the quantity of the emission of the electronic beam on all the vertical sections can be set to a minimum and the same and the irregular brightness on the picture can be reduced.

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, Plaquen tubes have been mainly used as display elements for displaying color television images, but the conventional Plaquen tubes have a very long depth compared to the screen size, making it difficult to use in thin televisions. It was impossible to create a receiver. In addition, although KL 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 been put into practical use. It has not yet been reached.

Therefore, the present applicant proposed a new display device in Japanese Patent Application No. 56-20618 (Japanese Unexamined Patent Publication No. 57-135590) to achieve a flat display device using electron beams.

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 of the image display element used here will be explained with reference to FIG. This display element consists of, in order from the back to the front, a back electrode (1), a line cathode (2) as a beam source, a vertical focusing electrode (3) (3'), a vertical deflection electrode (4), and a beam flow control It consists of an electrode (on), a horizontal focusing electrode (6), a horizontal deflection electrode (7), a beam accelerating electrode (8), and a screen (9), which are connected to a flat glass bulb (not shown). The interior is housed in a vacuum. Line cathode (2
) is stretched horizontally so as to generate an electron beam distributed linearly in the horizontal direction, and a plurality of such linear cathodes (2) are vertically spaced at appropriate intervals (in the figure, from (2 m) to
Only the four trees in (2b) are shown). In this example, it is assumed that 16 are provided. them (2
&)～(20)J-do. These wire cathodes (2) are composed of, for example, a 10-20 μΩ tungsten wire coated with an oxide cathode material for thermionic emission. These line cathodes (2&) to (2o) are heated so as to generate a thermionic beam by passing an electric current through them, and as described later, the line cathodes (2&) are heated sequentially for a certain period of time. It is controlled to emit an electron beam at a time. The back electrode (1) suppresses the generation of electron beams from other line cathodes other than the line cathode that is controlled to emit electron beams for a certain period of time, and directs the generated electron beams only in the forward direction. It has the effect of pushing out. This back electrode (
1) may be formed by a coating film of a conductive material adhered to the inner surface of the rear wall of the glass pulp. Furthermore, a planar electron beam emitting cathode may be used instead of the back electrode 0) and the line cathode (2).

The vertical focusing electrode (3) is a conductive plate (11) having a horizontally long slit (1o) facing each of the line cathodes (2m) to (2o), and it collects the electron beam emitted from the line cathode (2). taken out through the slit (10),
and vertically focused. Horizontal direction 1 line 9 (3
60 pixels worth of electron beams are taken out at the same time. In the diagram,
Of these, only one section in the horizontal direction is shown.

Pickpocket 7) In (10), bars may be provided at appropriate intervals in the middle, or a row of through holes arranged in large numbers at small intervals in the horizontal direction (intervals that are almost touching). may be configured substantially as a slit. The vertical focusing electrode (3') is also similar.

A plurality of vertical deflection electrodes (4) are arranged horizontally at intermediate positions between the above-mentioned slots 7) and (10), and conductors (1s) are placed on the upper and lower surfaces of the insulating substrate (12), respectively. (13'). Then, a vertical deflection voltage is applied between the opposing conductors (13) (1b) to deflect the electron beam in the vertical direction. In this example, the pair of conductors (13, 13') deflects the electron beam from the single-line cathode (2) to positions corresponding to 16 lines in the vertical direction. The 16 vertical deflection electrodes (4) constitute 16 conductor pairs corresponding to each of the 16 line cathodes (2), resulting in 240 horizontal lines on the screen (9) J:. Deflect the electron beam as you draw.

Next, the control electrodes (6) are composed of conductive plates (15) each having a vertically long slit 7) (14), and a plurality of control electrodes (15) are arranged in parallel in the horizontal direction at a predetermined interval.

In this example, 180 control electrode conductive plates (16-1) to
(15-n) is provided. (Only 9 lines 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 a video signal for displaying each picture element. Therefore, the conductive plate (1) for the control electrode (6)
If 180 lines of 5-1) to (1s-n) are provided, 360 picture elements can be displayed per horizontal line. In addition, in order to display images in color, each picture element has three colors: R, G, and B.
The display will be performed using colored phosphors, and each control electrode (6) will have R, (,) for two picture elements.

Each video signal of B is added sequentially. In addition, 180 sets (2 pixels per set) of video signals for 1 line are simultaneously applied to each of the 180 control electrodes (@ conductive plates (1s-1) to (1s-n)). Video for each line is displayed at once.

The horizontal focusing electrode (6) is connected to the slit (14) of the control electrode (5).
) is composed of a conductive plate (17) having a plurality of vertically long slits (16) facing each other, and the electron beam for each pixel divided horizontally is transmitted horizontally. Focus into a narrow beam of electrons.

A plurality of horizontal deflection electrodes (or conductive plates arranged vertically on both sides of each slit (16))
18) (1B'), each electrode (
18) A six-step horizontal deflection voltage is applied to (18') to deflect the electron beam for each picture element in the horizontal direction, so that each of the two sets of R, G, and B is displayed on the screen (9). The fluorescent bodies are sequentially illuminated 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) installed horizontally in the same position as the vertical deflection electrode (4), and it directs the electron beam to the screen (9) with sufficient energy. Accelerate to cause a collision.

The screen (9) is constructed by applying a phosphor (20) that emits light when irradiated with an electron beam to the back surface of a glass plate (21), and adding a metal back layer (not shown). The phosphor (2o) emits 3 colors of R, G, and H fluorescent light for each slit (14) of the control electrode (4), that is, for each of the divided electron beams in the horizontal direction. The dotted lines drawn on the screen (9) in Figure 3 correspond to each of the plurality of wire cathodes (2). The displayed vertical division is shown, and the dashed-two dotted line shows the horizontal division displayed corresponding to each of the plurality of control electrodes (5). As shown in an enlarged view in FIG. 4, there are R, G, and B phosphors (20) for two picture elements in the horizontal direction, and a width for 16 lines in the vertical direction. The size of one section is, for example, 1 m in the horizontal direction.

The vertical direction is 911II+.

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 this example, two R, G, and H phosphors (20) are used for one control electrode (b), that is, one electron beam.
Although only one pair of picture elements is provided, of course, one picture element or three or more picture elements may be provided, and in that case, one picture element or three or more picture elements are provided in the control electrode. R, G, and B video signals are sequentially applied for the purpose, and horizontal deflection is performed in synchronization with the R, G, and B video signals.

Next, the basic configuration and waveforms of each part 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 explained.

The power supply circuit (22) is a circuit for applying a predetermined bias voltage (operating voltage) to each electrode of the display element.
) for -v1, vertical focusing electrode (3) (3') for v5°Vs', horizontal focusing electrode (6) for v6, accelerating electrode (8)
A DC voltage of v8 is applied to the screen (9), and a DC voltage of v9 is applied to the screen (9).

Next, a composite video signal of a television signal is applied to the input terminal (23), and a vertical synchronization signal V and a horizontal synchronization signal H are separated and extracted in a synchronization separation circuit (24).

The vertical deflection drive circuit (40) includes vertical deflection kakuntas (2
6), a memory for vertical deflection signal storage (27), and a digital-to-analog converter (39) (hereinafter referred to as a DA converter). As input pulses to the vertical deflection drive circuit (4o), a vertical synchronizing signal gv and a horizontal synchronizing signal H shown in FIG. 6 are used. Kakunta (25) for vertical deflection (
8 bit) is reset by the vertical synchronizing signal V and counts the horizontal synchronizing signal 5+H. This vertical deflection kakunta (26) counts the effective scanning period (in this case, a period of 24 OH) excluding the vertical retrace period of the vertical period, and this count output is supplied to the address of the memory (27). be done. The memory (27) outputs vertical deflection signal data (8 pits in this case) corresponding to each address, and the D-A converter (39) outputs the vertical deflection signal data (8 pits in this case) as shown in FIG.
) is converted into a vertical deflection signal of p, t+' as shown in FIG.

In this circuit, there are memory addresses for storing vertical deflection signals corresponding to each line for 240H, and 16H
By storing regular data in the memory every minute, a 16-level vertical deflection signal can be obtained.

On the other hand, the line cathode drive circuit (26) creates line cathode drive pulses a-o using the vertical synchronization signal V and the output of the vertical deflection kakunta (26). Figure 6 (&) shows the vertical synchronization signal v
1 shows the relationship between the horizontal signal H and the lower five pits of the vertical deflection kakunta (25). FIG. 6(b) shows a method of creating line cathode drive pulses a' to 0' every 16H using these signals. In FIG. 6, LSB indicates the lowest bit, and (LSB+1) means the bit one higher than the LSB.

The first line cathode drive pulse a' is generated by using the vertical synchronizing signal V and the output (LSB+4) of the vertical deflection kakunta (25).
-S flip-flops etc. can be used to generate the line cathode drive pulses b' to 0' using a shift register, and the line cathode drive pulse a' to the output (LSB-1-3) of the vertical deflection converter (26). ) can be obtained by transferring the inverted version of Tarokku. This driving pulse a
° ~ 0' is inverted and brought to a low potential only during each pulse period,
During other periods, the pulses are converted into linear cathode drive pulses 4 to 0 at a high potential of about 20 volts (FIG. 6(b) K) and applied to each of the linear cathodes (2a) to (20).

Each line cathode (2a) to (20) is heated by passing a current during the high potential period of the driving pulse a~0, and is heated so that it can emit electrons during the low potential period of the driving pulse &~0. The heated state is maintained. This creates a 15-tree wire cathode (2a)
From ~(2o), low potential drive pulse &~0
Electrons are emitted only during the 16H period when . During periods when a high potential is applied, the line cathode (2&) Since the high potential applied to ~(2o) is positive, no electrons are emitted from the line cathodes (2&) ~(2o).

Thus, in the line cathode (2), during the effective vertical scanning period, the line cathode (2a) above is connected to the line cathode (20) below.
) electrons are sequentially emitted every 16H period. The emitted electrons are pushed forward by the back electrode (1) and are pushed forward by the facing slit (10) of the vertical focusing electrode (3).
) and is vertically focused into a flat electron beam.

Next, the line cathode drive pulse 2L~0 and the vertical deflection signal u,
The relationship with v' will be explained using FIG.

FIG. 8 (&) is a waveform diagram of the line cathode drive pulse, (b) is a waveform diagram of the vertical deflection signal, and (C) is a waveform diagram of the horizontal deflection signal. 8) vertical deflection signal v9. l is shown in Figure 8 (2
During the 16H period of each line cathode pulse a to 0 of L), it changes by 1L and changes in 16 steps. Vertical deflection signals V and V
′ and ′ both have a center voltage of v4, and V increases by 4 and υ′ sequentially decreases, so that they change in opposite directions. These vertical deflection signals V and V
' are the electrodes (13) and (1) of the vertical deflection electrode (4), respectively.
3'), so that each line cathode (2 &
) ~ (2o) The electron beam generated from
Deflected in 6 stages, as mentioned earlier the screen (9)
At the top, one electron beam is deflected so as to draw a 16-line raster one line at a time from the top.

As a result of the above, electron beams are emitted for each 16H period in order from the top of the 16 tree line cathodes (2&) to (20), and each electron beam is sequentially emitted one line from top to bottom within 16 vertical divisions. On the screen (9), from the first line at the top to the 24th line at the bottom.
The electron beam is vertically deflected one line at a time up to the 0th line, and a total of 240 raster lines are drawn.

The vertically deflected electron beam is sent to the control electrode (5).
It is divided into 180 sections in the horizontal direction by a horizontal focusing electrode (6) and taken out. In Figure 4, one of them
The classification is shown. The amount of this electron beam passing through each section is controlled by a control electrode (5), and is focused horizontally by a horizontal focusing electrode (6) into a single narrow electron beam. The R, G, and B6 phosphors (20)K for two picture elements on the screen (9) are sequentially irradiated by being deflected in six steps in the direction. FIG. 4 shows the vertical and horizontal divisions. The phosphors corresponding to (1s-1) to (1s-n) of the control electrode (6) are R, G, and B for two picture elements, but for convenience of explanation, one picture element is R1, Gj, B1 and the other Rz, G2
, B2.

Next, the horizontal deflection drive circuit (41) is composed of a horizontal deflection kakunta (2B) (11 bits), a memory (29) for storing horizontal deflection signals, and a D-hostage exchanger (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. 9, and uses a pulse 6H with a repetition frequency six times that of the horizontal synchronizing signal H. The horizontal deflection capacitor (28) is reset by the vertical synchronizing signal V and receives the horizontal six times the pulse 6.
Count H.

This horizontal deflection kakunta (28) is used 6 times during 1H, 1
The count is counted 240H×6/H=1440 times during v, and this count output is supplied to the address of the memory (29). The memory (29) outputs horizontal deflection signal data (here 8 bits) according to the address, and the D-hostage exchanger (38) outputs it as shown in Figure 9 (Figure 6 (b) ()K). ,
It is converted into a horizontal deflection signal such as h'. 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, the horizontal deflection signal of 6-step waves during the IH open 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 six steps, both of which have a center voltage of V, where h decreases sequentially and h' increases sequentially. They change in opposite directions as they move forward. These horizontal deflection signals h 1 and h' are respectively applied to electrodes (18) and (1a') of the horizontal deflection electrode (7').

As a result, each horizontally segmented electron beam is applied 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.Rz, Gz, Bz) are sequentially irradiated for H/6 periods each. Thus, in each line of Rask, the electron beams are R1 and Gj for each of the 180 sections in the horizontal direction.

B1. R2, G2. B2 Each phosphor (20) is sequentially irradiated.

Therefore, the electron beam is set to R1, G for each horizontal section of each line.
1. B+, R2, G2. By modulating with 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 and the G-Y color difference signal is demodulated. The signals are matrix-synthesized, and further, they are combined with the luminance signal Y to generate R, G, and H primary color signals (hereinafter R,
G, B video signals) are output. Those R,G
, B6 video signal is passed through a 180m sample hold circuit (3
1-1) to (al-n). Each sample hold circuit (31-1) to (31-n) is R1
It has six sample and hold circuits: 1, G1, B1, R2, G2, and B2. Those sample and hold outputs are stored in the holding memories (32-1) to (32-1), respectively.
2-n).

On the other hand, the reference clock oscillator (33) is composed of a PLL (phase-locked loop) circuit, etc., and in this example, the reference clock efs is six times as large as the color subcarrier fsc.
A reference clock 2fsc, which is twice as large as the reference clock 2fsc, is generated. The reference clock is controlled to always have a constant phase with respect to the horizontal synchronizing signal H.

Reference clock 2 fBo is the deflection pulse generation circuit (42
), and the signals 6H and H/6 times the horizontal synchronization signal H are added to
Signal switching every 8 C/L/S"1+gi +b1 +r
A pulse of 2+g2+b2 (B) in FIG. 6 is obtained.

On the other hand, a reference clock of 6 ft is applied to the output sampling pulse generation circuit (34), where it is delayed by one tarok period by a shift register, thereby increasing the effective horizontal scanning period of the horizontal period (63.5 μsec). (approximately 60μSθC) IC 1080 sampling pulses R11, G11.B++, R12, G12.B12
, 11. G21.

Bzl, R22, G22, B22~RJ, Gnl
, Bnl, Rn2.

Gn2. Rn2 (FIG. 5(b) A) is generated sequentially, and then one transfer pulse t is generated. These sampling pulses R11 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.

Each of these 1080 sampling pulses R11 to Bn2 is connected to 180 sets of sample hold circuits (31-1).
~(31-n) are added to each sample hold circuit (31-1) to (31-n) by 6.
When the line is divided into 180 lines, the video signals of R1, Gj, Bl, R2, G2, and B2 for each two picture elements are individually sampled and held. The sampled and held 180 pairs of R1, Gt, B1°R2, G2 . 180 sets of memory (32-1) to (32
-n), are transferred all at once by a transfer pulse t, and are held here for the next horizontal period. This retained R1.
The signals Gj, B1, R2, G2, and B2 are applied to switching circuits (35-1) to (35-n). The switching circuits (35-1) to (35-n) each have R1, Gl, B1. R2, G2. It is composed of a tri-state analog gate having individual input terminals of B2 and a common output terminal that sequentially switches and outputs them.

Each switching circuit (35-1) to (36-n) has 180 sets of pulse width modulation (PWM) circuit (37-1).
~(37-n) where the sampled and held R1, G1, B1, R2, G2, B
2. The reference pulse signal is pulse width modulated by the magnitude KF5 of the video signal and output. The repetition period of the reference pulse signal is the signal switching pulse r1. g+, b1. r2
°g2. It is desirable that the pulse width be sufficiently smaller than the pulse width of b2, and for example, a pulse width of about 1:10 to 1:100 is used.

The outputs of the pulse width modulation circuits (37-1) to (37-n) are used as control signals for modulating the electron beam to the 180 conductive plates (15-1) to the control electrodes (5) of the display element.
(15-n) respectively. The switching circuits (35-1) to (35-n) are simultaneously controlled by switching pulses "+g' +b1, r2.g2.b2" applied from the switching pulse generation circuit (36).
6) is the deflection pulse generation circuit (42) to ()) described above.
Signal 9J conversion Hals r1, gl, k)1, r2,
g2, b2 K are controlled horizontally, and each horizontal period is divided into 6, and each switching circuit (35-1) is divided into H/6.
~(3s-n), R1, G1, B1, R2
, G2, and B2 are time-divided and sequentially output.
The switching signal r1.K is supplied to the pulse width modulation circuits (37-1) to (37-n). g1゜bl, r2. g2.
b2 wo occurs.

What should be noted here is that the switching circuit (35-1
) to (35-n), R1, Gi, B1,
R2.

G2. B2 video signal supply switching and electron beams R1, G1 . B1, R2
゜G2. The horizontal deflection for switching the irradiation to the phosphor B2 is synchronously controlled so that it completely matches both the timing and the 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. B2 is similarly controlled, and R1, Gj, B1, and R2 of each picture element.

G2. B2 The emission of each party light is R1, Gt of the picture element,
B1°R2, G2. Each picture element is controlled by the B2 video signal, and each picture element is displayed by emitting light according to the input video signal. This control is for one line.
This is done simultaneously for 80 sets (2 picture elements each) to display an image of 360 pixels per line, and then for 24 OH lines sequentially starting from the upper line, so that one image is displayed on the screen (9). It will be displayed.

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

Problems to be Solved by the Invention However, with the above configuration, there is a problem that variations in brightness occur in each vertical section on the screen due to variations in electrode assembly precision, processing precision, material quality, etc. . In order to compensate for such variations in brightness and make the brightness uniform, it is generally necessary to perform feedback control. However, if the feedback loose convergence value is fixed to a constant value, it is not possible to deal with deterioration of the electron beam or variations in the initial setting value for each set, and the brightness is changed for each vertical section. This had the problem of causing variations in the results.

In view of the above-mentioned problems, it is an object of the present invention to provide an image display device that can always make the brightness of each vertical section the same.

Means for Solving the Problems In order to solve the above problems, the image display device of the present invention constantly detects a reference value in the feedback loop for making the brightness on the screen constant for each vertical segment. The present invention is provided with a configuration that includes means for supplying the reference value as a reference value for feedback looseness.

By inventing the function tree and using the above configuration to constantly detect and supply the feedback reference value, it is possible to always obtain the appropriate reference value even if there is emission deterioration of the electron beam source or variations from set to set. feedback will be provided.

Embodiment Hereinafter, an image display device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a luminance Paranki compensation circuit for an image display device according to a first embodiment of the present invention.

In Fig. 1, there are 61 vertical focusing electrodes (G1), 6 detection resistors, 6
A differential amplifier for extracting the signal detected by the two detection resistors 51 passes the signal from the differential amplifier 52 when the 63 vertical blanking pulses are low level, and outputs the signal from the high level voltage source 64. It is an analog switch that switches to adjust the voltage. This is a voltage source for applying a voltage lower than the detection signal to the peak hold circuit 15 when the vertical blanking pulse of the voltage source 64 is at a high level to prevent the hold value from changing. 56 peak hold circuit, 56 detection signal and peak hold circuit 65
, and an inverter amplifier that inverts the output signal from the 67 differential amplifier 56 and multiplies it by 1/n. 58
is a variable voltage source that changes the driving voltage applied to the vertical focusing electrode (G1) 3 according to a compensation signal from the differential amplifier 56;
This is a variable voltage source that changes the drive voltage applied to the 59 back electrodes 1 using a compensation signal from an inverter amplifier 67.

The operation of the brightness variation compensation circuit configured as described above will be explained below using FIG. 2.

FIG. 2 shows the detection signal waveform from the detection resistor 61. When a line cathode that emits a large amount of electron beam is operated, the value of the current flowing into the vertical focusing electrode 3 in that vertical section is larger than that in other vertical sections of the line cathode, so the detection from the detection resistor 61 is The voltage is lower with respect to ground.

Therefore, by detecting the positive peak value of the detection signal during the period excluding the vertical blanking period, the vertical focusing electrode in the darkest vertical section corresponding to the line cathode with the least amount of electron beam emission is detected. The value of the current flowing into (G1) 3 can be detected.

Therefore, by using this vertical section with the lowest brightness as a reference and adjusting the brightness of the other vertical sections to match the brightness of this vertical section, it is possible to control the brightness of the entire screen to always be uniform. In FIG. 1, the detection output signal from the detection resistor 51 is applied to a peak hold circuit 66 during a period other than vertical blanking, so that its peak value is detected. During the vertical blanking period, a low DC voltage value from the voltage source 54 is applied to eliminate the effects of that period. The peak held peak value signal is applied to the differential amplifier 56 as a feedback loose reference value,
Here, the difference with the detection signal from the differential amplifier 62 is detected and a feedback loop is performed for each vertical section by the voltage source 58.
59 is used as a compensation signal for controlling the signal.

This makes it possible to align the emission amount of the electron beam in all vertical sections to be the same as that of the line cathode with the minimum emission amount, and it is possible to reduce variations in brightness on the screen.

Note that the compensation signal for controlling the emission amount of the electron beam source can be applied to any part other than the above-mentioned electrodes, such as the electron beam source itself or other electrodes, as long as the amount of electron beam emission can be controlled. can.

Effects of the Invention As described above, according to the present invention, by providing a function to constantly detect and supply the reference value of the feedback loop for controlling the electron beam source and keeping the brightness constant, emission deterioration and set Even if there are variations from time to time, it is possible to always supply an appropriate reference value in accordance with the variation, and it is possible to reduce variations in luminance as a whole screen.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the main parts of an image display device according to an embodiment of the present invention, FIG. 2 is a waveform diagram showing its detection signal, and FIG.
The figure is an exploded perspective view of an image display element used in a conventional image display device, Figure 4 is an enlarged view of the fluorescent surface of the image display element, and Figure 6 shows the basic configuration of the drive circuit of the image display element. 6 is a waveform diagram for explaining the operation of the vertical deflection drive circuit, FIG. 7 is a waveform diagram for explaining the operation of the line cathode drive circuit, and FIG. 8 is a waveform diagram for explaining the operation of the vertical deflection drive circuit. FIG. 9 is a waveform diagram for explaining the operation of the horizontal deflection drive circuit. (1)... Back electrode, (2), (2L) ~ (2
o)... Line cathode, (3)... Vertical focusing electrode, (4)... Vertical deflection electrode, (5)...
... Beam flow control electrode, (η ... Horizontal deflection electrode, (9) ... Screen, (20) ...
... Fluorescent body, (26) ... Vertical deflection force, (26) ... Line cathode drive circuit, (27) ...
...Memory, (3o) ...Color demodulation circuit, (
4o)... Vertical deflection drive circuit, (41)...
... Horizontal deflection drive circuit, (42) ... Deflection pulse generation circuit, (61) ... Detection resistor, (5
2) l (56)...Differential amplifier, (53)
...Analog switch, (SS)...
Peak hold circuit, (67)... Inverter amplifier, (5B), (59)... Variable voltage source. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure Vertical Fufu 7 Yang 7° Karika 4th Figure Nod, + Lagu 11 /Z-ta), 6th Figure, l L'' Figure 7 (α)

Claims (1)

[Claims] a screen coated with a phosphor that emits light when irradiated with an electron beam; an electron beam source that generates an electron beam for each vertical section of the screen divided into a plurality of vertical sections; Separating means for separating the electron beam generated by the beam source into each horizontal section and irradiating it onto the screen; and a deflection electrode that deflects the electron beam in multiple stages before reaching the screen. a beam flow control electrode that controls the amount of emitted light from each pixel on the screen by controlling the amount of electron beams separated for each horizontal section irradiated onto the screen; a focusing electrode for controlling the size of light emitted on the surface of the phosphor, a back electrode for controlling the amount of electron beam generated from the electron beam source, and an accelerating electrode for accelerating the electron beam irradiation onto the screen; a detection means for detecting the brightness of each vertical section; and at least one of the electron beam source, any of the electrodes, and the accelerating electrode so as to equalize the brightness of each vertical section to a reference value based on the detection output thereof. An image display device characterized in that it is equipped with a feedback loop that controls one.