JPS60220680A - Picture display device - Google Patents

Abstract

PURPOSE:To accurately make a luminance level correspond to signal modulation, by impressing a pulse upon a focusing electrode synchronously to the off-timing of an enable pulse signal and forcedly inhibiting the pass of an electron beam during this period. CONSTITUTION:When an enable pulse EP is impressed, a transistor 70 is conducted through an inverter 80 and, further, transistors 72 and 76 are conducted. Then an output pulse of -30V is outputted to the collector of the transistor 76. That is to say, while a voltage VB of about 0V (VB=apprx. 0V) is normally applied across a horizontal focusing electrode 6, the voltage of -30V is applied across the horizontal focusing electrode 6 during the period when the EP pulse is impressed and the pass of an electron beam to the downstream side of the horizontal focusing electrode 6 is inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention generates an electron beam for each vertical section when a screen is divided into a plurality of sections vertically and horizontally.

The present invention relates to a device that displays a television screen image as a whole by deflecting each electron beam in the vertical and horizontal directions for each horizontal section.

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 shaped television receiver. In addition, recently L≧L display elements, plasma display devices, liquid crystal display elements, etc. have been developed as planar display elements, but all of them are insufficient in terms of performance such as brightness, contrast, and color display, and are not suitable for practical use. It has not yet reached the point where it will be done.

Therefore, in order to achieve a flat display device using electron beams, the present applicant filed Japanese Patent Application No. 56-20618 (
A novel display device was proposed in Japanese Patent Application Laid-Open No. 58-136590.

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, a television image is displayed as a whole.0 First, a basic configuration example of an image display element used here will be described 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, vertical focusing electrodes 3, 3,
Vertical deflection electrode 4, beam flow control electrode 6, horizontal focusing electrode 6
, a horizontal deflection electrode 7, a beam acceleration electrode 8, and a screen plate 9 are arranged, and these are housed inside a flat glass bulb (not shown) which is made into a vacuum.

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 are arranged vertically at appropriate intervals ( In this embodiment, 16 wires are provided (only four wires 2A to 22 are shown). Let's call them 2i~2yo. These wire cathodes 2 are constructed by coating the surface of a tungsten wire with a diameter of 10 to 20 μΦ with an oxide cathode material for thermionic emission.

These line cathodes 2A to 2Y are heated by generating a thermionic electron beam when a current is passed through them, and as described later, the electron beams are emitted from the line cathode 2I for a certain period of time in order from the line cathode 2I. controlled to emit. The back electrode 1 suppresses the generation of electron beams from other line cathodes 2 other than the line cathode 2 that is controlled to emit the electron beam at a certain time, and directs the generated electron beams forward. It has the effect of pushing out toward the target. The back electrode 1 may be formed by a coating of a conductive material applied to the inner surface of the rear wall of the glass bulb. Further, instead of the back electrode 1 and the linear cathode 2, a planar electron beam emitting cathode may be used.

The vertical focusing electrode 3 is a conductive plate 11 having a horizontally long slit 1o facing each of the line cathodes 2a to 2yo, and collects the electron beam emitted from the line cathode 2 into the slit.
10 and vertically focused.

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 it may be a row of through holes provided in a large number at small intervals in the horizontal direction (so that they almost touch each other). Alternatively, it may be configured as a slit. The vertical focusing electrode 3' is also similar.

A plurality of vertical deflection electrodes 4 are arranged horizontally in the middle of each of the slits 10, and 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' to deflect the electron beam in the vertical direction. In this example,
A pair of conductors 13 and 13' deflect the electron beam from one line cathode 2 to positions corresponding to 16 lines in the vertical direction.

Then, 16 vertical deflection electrodes 4 provide 16 i1
Fifteen conductor pairs corresponding to each of the J cathodes 2 are constructed, and the electron beam is ultimately deflected to draw 240 horizontal lines on the screen 9.

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 at predetermined intervals. In this embodiment, 180 conductive plates 15a to 15n for control electrodes are provided (only 9 are shown in the figure). Each of the control electrodes 6 spreads the electron beam horizontally by two pixels. The amount of passage is controlled according to the video signal for displaying each picture element.

Therefore, if 180 conductive plates 15a to 15n for the control electrode 6 are provided, 360 pixels can be displayed per horizontal line.In order to display images in color, each pixel is R , G, and B, and
To each control electrode 6, R, G, and B video signals for two picture elements are sequentially applied. Each of the 180 conductive plates 15a to 15n for the control electrode 6 has 180 pairs for one line (01).
Two picture elements per set of video signals are applied simultaneously, 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) facing the slits 14 of the control electrode 6, and collects electrons for each picture element divided in the horizontal direction. Each beam is focused horizontally into a narrow electron beam.

The horizontal deflection electrodes 7 include a plurality of conductive plates 18.1 arranged vertically on both sides of the slit 16.
8', six levels of horizontal deflection voltage are applied to each electrode 18, 18' to horizontally deflect the electron beam for each pixel, and to generate two sets of electron beams on the screen 9. The R, G, and H phosphors are sequentially irradiated to emit light.

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

The acceleration electrode 8 is composed of a plurality of conductive plates 19 provided horizontally at the same position as the vertical deflection electrode 4.
The electron beam is accelerated to collide 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 glass plate 21, and adding a metal back layer (not shown).

The phosphors 20 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 vertically in strips and live. 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 5. Indicates the horizontal division that will be displayed. As shown in the enlarged view in Figure 2, one section partitioned by these two has two R, G, and B phosphors for two picture elements in the horizontal direction.
0, and has a width of 16 lines in the vertical direction. For example, the size of one section is 1 g in the horizontal direction.
, the vertical direction is 10 chu.

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

Further, in this embodiment, only one pair of R2σ, B phosphors 20 for two picture elements is provided for one control electrode 6, that is, for one electron beam. Three or more picture elements may be provided, and in that case, the control electrode 6 has R, G, and B for one picture element or three or more picture elements.
Video signals are applied sequentially, and horizontal deflection is performed cyclically.

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. 6 for v6, acceleration electrode 8 for v8, screen 9
A DC voltage of Fiv is applied to.

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

The vertical deflection drive circuit 40 includes a vertical deflection counter 26,
It is composed of a memory 27 for storing vertical deflection signals and a digital-to-analog converter 39 (hereinafter referred to as a single converter). The input pulse of the vertical deflection drive circuit 40 is as follows:
A vertical synchronization signal V and a horizontal synchronization signal H shown in FIG. 4 are used. Vertical deflection counter 25 (8 pins) tl;t is reset by the vertical synchronizing signal V and counts the horizontal synchronizing signal H. This vertical deflection counter 25 counts the effective scanning period (here, a period of 240H) excluding the vertical retrace period of the vertical period, and this count output is supplied to the address of the memory 27. memory 2
7 outputs vertical deflection signal data (here, 8 bits) corresponding to each address, and the D-A converter 39 outputs the data of the vertical deflection signal corresponding to each address.
V shown in the figure.

V' is converted into a vertical deflection signal. In this circuit 240
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. 5 (a+ is the vertical synchronizing signal V, the horizontal synchronizing signal H, and the lower 5
Shows the relationship between bits. FIG. 5(b) shows a method of creating line cathode drive pulses [A' to Y'] every 16H using these signals. In FIG. 6, LSB indicates the lowest bit, and (LSB4-1) 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'] can be obtained 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. I can do it. This drive pulse [A' to Yo'] is inverted and made to have a low potential only during each pulse period, and is converted into a line cathode drive pulse [I to Yo] with a high unit of about 20 volts during other periods. , are added to each line cathode 2i to 2yo.

Each of the line cathodes 2i to 2yo is heated by passing a current between the high potentials of the drive pulses [i to j], and the drive pulses [
The heated state is maintained so that electrons can be emitted during the low potential period (I to Y). As a result, 15 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 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 vertically focused 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, v' are one of each line cathode pulse [I to Y]
During the 6H period, it changes in steps of 1H and changes in 16 steps. The vertical deflection signals V and V' both have a center voltage of v4, and are varied in opposite directions (P-) so that V increases sequentially and V' decreases sequentially. .These vertical deflection electrodes 4 and V' are the vertical deflection electrodes 4, respectively.
As a result, the electron beams generated from the respective line cathodes 2I to 2Y are vertically deflected in 16 steps, and are applied to the screen 9 as described above.
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 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 1 shows one of these categories. The amount of electron beam passing through each section is controlled by the control electrode 5, and is focused in the horizontal direction by the horizontal focusing electrode θ to become one narrow electron beam.
It is deflected horizontally in six steps by the horizontal deflection means described below, and is sequentially irradiated onto the phosphor 20 of two picture elements (, G, B6) on the screen 9. 15a to 1 of the control electrodes 5, respectively.
The phosphor corresponding to 5n is R, G, and B for two picture elements, but for convenience of explanation, let one picture element be fR+G,,B, and the other one is 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 a horizontal deflection signal, and a D-large converter 38. As shown in FIG. 7, the input pulses of the horizontal deflection drive circuit 41 are synchronized with the vertical synchronizing signal V and the horizontal synchronizing signal H, and a pulse 6H having a repetition frequency six times that of the horizontal synchronizing signal H is used.

The horizontal deflection counter 28 is reset by the vertical synchronizing signal V and counts the horizontal six-fold pulse 6H. This horizontal deflection counter 28 is 1H nJIK 6 times, 1
It counts 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-large converter 38
Then, it is converted into a horizontal deflection signal such as h' as shown in FIG. This circuit has memory addresses for storing horizontal deflection signals corresponding to each of 6 x 240 lines, and by storing 6 pieces of regular data for each line in the memory, 6-step horizontal waves are generated in 1H period. A deflection signal can be obtained.

As shown in Fig. 7, this horizontal deflection signal is a pair of horizontal deflection signals ri and h' that change in 6 steps, both of which have a center voltage of v7, where h decreases sequentially and h' increases sequentially. They change in opposite directions as they move forward. These horizontal deflection signals h' are electrodes 18 and 1 of the horizontal deflection electrode 7, respectively.
8' is added.

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

G, B (Rle G, + B, + R2+ G2+
It is horizontally deflected so that the phosphors of B2) are sequentially irradiated with H/6. Thus, in the raster of each line, the electron beam for each of the 180 sections in the horizontal direction is R1°G, B, R2, G2 . Each phosphor 20 of B2 is sequentially irradiated with 1 ray of light.

Therefore, the electron beams are set to R, , G for each horizontal section of each line.
1. B1. A color television image can be displayed on the screen 9 by modulating the video signal R2, (r2.B2).

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, where the R-Y
The color difference signals of and B-Y are demodulated, the color difference signals of (, -Y, and These R, G, and B6 video signals are output from 180 sample and hold circuit sets 31a to 3.
0 added to 1n Each sample hold circuit set 31a~
31n are for R1, G, B, R2, and G, respectively.
It has six sample and hold circuits for B2 and B2. These sample and hold outputs are respectively applied to holding memory sets 32a to 32n.

On the other hand, the reference clock oscillator 33 is constituted by a PLL (phase-locked loop) circuit, etc., and in this embodiment, the reference clock 6f is six times as large as the color subcarrier fIlo.
sc and double reference clock 2'! Generate IC. The reference clock is controlled to always have a phase of one foot with respect to the horizontal synchronizing signal H. Reference clock "v+c"
is added to the deflection pulse generating circuit 42, and a signal 6H, which is six times the horizontal synchronizing signal H, and a signal switching pulse for each i, ``, +
A pulse of 91+b1+r21q2 y B2 is obtained. On the other hand, the reference clock 6fsc is applied to the sampling pulse generation circuit 34, where it is delayed by one clock period by a shift register, etc., so that the horizontal period < em
, tsμ5ec) of the effective horizontal scanning period (approximately 60μ
sec) 1080 sampling pulses Ra
+ to Bn2 are generated sequentially, and then one transfer pulse t is generated. This sampling pulse Ra+~Bn
2 corresponds to each picture element when one line of the video to be displayed is divided into 360 picture elements in the horizontal direction, and the position thereof is controlled so as to be always constant with respect to the horizontal synchronizing signal H.

These 1080 sampling pulses Ra+ to Bn2 correspond to 180 sample and hold circuit sets 31a to 3, respectively.
1n, and as a result, each sample-and-hold circuit set 31a to 31n has two picture elements of RG, , B1 . R2
, G2. B2-1 Each video signal is individually sampled and held.

For the sample-held 180 pairs of R, ,
B, , R2, G2. After the sample and hold for one line is completed, the B2 video signal is transferred all at once to the 180 fill memories 32a to 32n by a transfer pulse t, where it is held for the next horizontal period.

This retained R, , (rl, B, , R2,
G2. The signal of B2 is sent to the switching circuits 35a to 3.5.
added to n. The switching circuits 35a to 35n are tristate or analog gates each having individual input terminals for R, , G, , B, , R2, G, , , B, and a common output terminal for sequentially switching and outputting them. It is constructed.

The output of each switching circuit 35a-35n is applied to 180 sets of pulse width modulation (PWM) circuits 37a-37n, where sampled and held R, , (r,
, B4. 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 above signal switching pulse "1 r ql r blr r2 + q2 +
It is desirable that the pulse width be sufficiently smaller than the pulse width of b2, and for example, a pulse width of about 1:1o to 1:100 is used.

The outputs of the pulse width modulation circuits 37a to 3711 are individually applied to the 180 conductive plates 15a to 15F+ of the control electrode 6 of the display element as control signals for modulating the electron beam. Each of the switching circuits 35a to ssn receives switching pulses r1q5 . b4. r2. q2. Switching is controlled simultaneously by b2. The switching pulse generation circuit 36 is controlled by the signal switching signal from the deflection pulse generation circuit 42 described above (Rus', +q, r, +2 +'J2 +b2), and each horizontal period is divided into six to generate H/e.
Switching the switching circuits 35a to 35n each time, R11
G, , B1. R2, G2. Each video signal of B2 is time-divided and sequentially outputted to the pulse width modulation circuits 37a to 3.
The switching signal r1.7n is supplied to the switching signal r1.7n. q1. b1. r2
゜b2. Generate q2.

What should be noted here is that the switching circuits 36a to 3
R, , G, , B1. in 5n. R2°G2.
B2 video signal supply switching and horizontal deflection drive circuit 4
1 by electron beam R,,G1. B.

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 G+ l Bl l R21G2 'B2
R9G and B of each picture element are also controlled in the same way.
, , R2, (r2. B2 The light emission of each phosphor is controlled by the video signal of R,, G, , B1. The light is displayed in accordance with the video signal.

Such control is performed simultaneously for 180 sets of one line (2 picture elements each) to display an image of 360 picture elements for one line, and then sequentially for 240 minutes of lines starting from the upper line. One image 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.

In the image display device described above, the PWM as shown in FIG.
Approximately 40 Vp is applied to the circuits 37a to 37n when K is actually applied to the control electrode of the image display device (see 5 in FIG. 1).
It has a built-in pulse amplification circuit that obtains pulses of p.

The output of this PWM circuit and the horizontal deflection waveform (Fig. 3,
Figure 8 shows the correlation with h'). In this figure, the person in figure 8 is
It is a PWM signal with a pulse width proportional to the brightness level of the image, and the three left pulses in the 1H period indicate the maximum brightness.

Figure 8B shows a pulse (enable pulse, hereinafter referred to as IP) that indicates the period during which the PWM wave is output, and this EP is II.
The PWM signal is output only during the H11 period. Finally, the reset timing of the PWM signal is determined by the falling edge of RP.

Therefore, all outputs of the brightness modulation PWM signals of this system are reset at the same time, and during the EP L'' period, the PWM waveform is forced to 1L'' and no output is made.

FIG. 8C shows the horizontal deflection output waveform shown in FIG. The size of the HP L'' period is designed in consideration of the roundness at the rise and fall of this horizontal deflection output waveform, and is approximately 1 μB.

Figure 8: To create a human PWM output waveform, an amplifier circuit as shown in Figure 9 has been proposed. FIG. 9 will be explained. This pulse amplification circuit allows current to flow from the output terminal to the ground point during the period when the input pulse viO is at a high level, and the input pulse Y
During the low voltage period of i, a current flows from the power supply V (=40V) to the output terminal C1, and at the moment the input pulse vi becomes low level, the power supply V.

It is configured so that a peak current flows from C1 to the output terminal. In the figure, 60.61 is a transistor for current amplification that constitutes a bushoguru circuit, 58.591-i is a transistor and a resistor that constitutes an emitter input circuit, 6o and 61 are transistors and resistors that constitute an inverting amplifier circuit, and 56 and 62 are transistors and resistors that constitute an inverting amplifier circuit. A transistor and a resistor constitute an emitter follower circuit, and as shown in FIG. 10, an output pulse V which is an inversion of the input pulse Vi is applied to the emitter. 55 is obtained. 53, 63 and 64 are capacitors, diodes and resistors forming a differentiating circuit, which are inserted between the emitter follower transistor 55 and the base of the switching transistor 620,
This causes the base of the transistor 52 to receive the output pulse v.
A differential pulse vb52 generated at the rising edge of 855, that is, at the falling edge of the input pulse Vi, is added. During the period of this differential pulse, the switching transistor 52
The conductor is connected to its collector at this moment. A current of 52 flows. 6θ and 67 are transistors and resistors that constitute an inverting amplifier circuit, and a current of 66 flows through the resistor 66 connected to the emitter of the transistor 66, so that the collector of the transistor 66 has a current of 52 and 6. In the added process, a current 56 flows. This current is amplified through transistors 50 and 57 and supplied to the output terminal. On the other hand, the input pulse vi is supplied to the emitter input circuit consisting of a transistor 64 and a resistor 69. is applied to the transistor 68.51 through the input pulse v1, causing a current to flow from the output terminal to the ground point during the high level period of the input pulse v1.As a result, the output terminal has an output voltage V as shown in FIG. 10H. Obtainable.

However, this circuit has some problems as described below.
,-ell 111is! I ksu μ=2λ Nano Zn-=tVx L un,: Lux and output pulse T
This shows the relationship between o. Here, C in FIG. 11 is an output pulse corresponding to person X in FIG. 8, and is an ideal output waveform.

However, in reality, the output pulse waveform becomes a distorted waveform as shown in Figure 11. Further, E indicates a range in which the control electrode maintains an ON state (not completely) even if the peak value of this PWM output pulse waveform decreases. E
The range of is about 30V in this system.

In the waveform shown in Figure 11, the brightness level and signal modulation do not correspond as described above, and this poses a serious problem in terms of visibility. Solving this problem by improving the circuit shown in FIG. 9 and making the fall of the output pulse vo steeper is not a good idea in terms of power and packaging since there are 180 outputs.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned problems, and an object of the present invention is to provide an image display device in which the brightness level of a video signal and signal modulation correspond accurately.

Structure of the Invention The present invention forcibly applies a pulse to a focusing electrode in synchronization with the turn-off timing of an output pulse signal modulated in pulse width of a video signal applied to a control electrode. By preventing the light from passing through the focusing electrode, an off state of signal modulation is created, and as a result, an output pulse that corresponds precisely to the brightness level can be applied to the control electrode in an isometric manner.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 12 and 13. This embodiment is an example in which the present invention is applied to a horizontal focusing electrode, and the voltage applied to the horizontal focusing electrode 6 (VB - approximately OV
) is the period during which the KP pulse is applied, for example -30
V to prevent the electron beam from passing through from this horizontal focusing electrode 6 onwards. In FIG. 12, 100 is an EP pulse amplification circuit, which includes a transistor 70 and a resistor 71, which also constitute an emitter follower circuit, a transistor 72 and a resistor 79, and a transistor 76.
, a resistor 3 that determines the potential of the transistor 72, a diode 4, a capacitor 76 connecting the emitter of the transistor 7Q and the base of the transistor 72, a base resistor 77, 78, and an inverter 80. When the EP pulse shown in FIG. 13B is applied, the transistor 70 becomes conductive via the inverter 80, and the transistors 72 and 76 become conductive, so that the collector of the transistor 76 receives the -30V output pulse shown in FIG. Output. That is, the horizontal focusing electrode 6 normally has (V, =
During the application of this IP pulse, a voltage of -30V is applied to the horizontal focusing electrode 6 to prevent the electron beam from passing through the horizontal focusing electrode. This circuit 100 only needs to be installed as one circuit, so the power consumption is small.
Sufficient characteristics can be obtained by increasing the power (300 mW). FIG. 13X shows the period during which the phosphor on the screen 9 emits light, the broken line portion is the unnecessary period that occurs conventionally, and the diagonal line portion is the period obtained by adopting the present configuration.

In the above example, the amplified ΣP pulse is applied to the horizontal focusing electrode, but the invention is not limited to this, and it may be applied to the vertical focusing electrode.

In this way, when performing signal modulation with PWM, the set timing (off → on) uses the conventional rise shown in Figure 8, and the reset timing (on → off) is set using the pulse of this device (as shown in Figure 12). By performing step D), the passage of the electron beam is controlled and brightness modulation is performed.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) The brightness change corresponds to the input signal modulation pulse width, resulting in correct visual characteristics.

(2) Since the characteristic of the conventional signal modulation circuit can be relaxed until it drops by about 30V in about 1 μs, the power can be reduced.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of an image display element used in an image display device according to an embodiment of the present invention, FIG. 2 is an enlarged view of the fluorescent surface of the image display element, and FIG. A block diagram of a drive circuit devised prior to the present invention for driving, FIG. 4, FIG. 6, FIG. 6, and FIG. 7 are waveform diagrams of various parts for explaining the operation of the drive circuit, respectively. Fig. 8 is a waveform diagram showing the correlation between the pwM output waveform and the horizontal deflection output waveform, Fig. 9 is a circuit diagram of the pulse amplification device included in the PWM circuit, and Fig. 10 is a diagram for explaining the operation of the 90th circuit. 11 is a waveform diagram explaining the problems of the circuit in FIG. 9, FIG. 12 is a circuit diagram of the main part of an image display device in an embodiment of the present invention, and FIG. FIG. 3 is a waveform diagram for explaining the operation. 2.2 I~2 Y... Line cathode, 4... Vertical deflection electrode, 5... Beam flow control electrode, 7...
...Horizontal deflection electrode, 9...Screen plate,
10... Slit, 20... Fluorescent material,
23...Input terminal, 24...Synchronization separation circuit, 25...Vertical deflection counter, 26
... Line cathode drive circuit, 27 ... Memory, 28 ... Horizontal internal counter, 29 ...
...Memory, 30 ...Color demodulation circuit, 31a-31
n...Sample hold circuit, 32a to 32n
...Memory, 33...Reference clock oscillator, 3.4...Sampling pulse generation circuit, 3
5a-35n...Switching circuit, 36...
...Switching pulse generation circuit, 37a to 37n
...PWM circuit, 38...D/A converter, 3
9...Converter to D/, 4o...Vertical deflection drive circuit, 41...Horizontal deflection drive circuit, 42
...Deflection pulse generation circuit, 100...
HP pulse amplification circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Fig. 2θ 18 words of Mizute 8 words工”-1-” EP 'n

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 division of the screen on the screen; a horizontal separating means for separating the electron beam generated by the electron beam source into each of the plurality of horizontal divisions of the screen on the screen and irradiating the electron beam onto the screen; A deflection electrode that deflects the electron beam in multiple steps vertically and horizontally between An image display element having a signal electrode for controlling the amount of light emitted, a focusing electrode for controlling the size of light emitted by the electron beam on the phosphor surface in each picture element, and a back electrode for controlling the amount of the electron beam generated, Turn off the PWM pulse signal applied to the signal electrode (brightness is 0)
An image display device characterized in that a pulse is applied to the focusing electrode in synchronization with the timing of the state in which the electron beam is forced to pass through the focusing electrode during this period.