JP2600664B2 - Image display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generates an electron beam for each section when a screen on a screen is divided into a plurality of sections in a vertical direction, and generates an electron beam for each section. The present invention relates to an apparatus for displaying a plurality of lines by deflecting a beam in a vertical direction and displaying a television image as a whole.

2. Description of the Related Art Conventionally, a cathode ray tube is mainly used as a display element for displaying a color television image. However, the conventional cathode ray tube has a very long depth compared to the size of a screen, and a thin television receiver. It was impossible to create a machine. Recently, EL display devices, plasma display devices, liquid crystal display devices, and the like have been developed as flat display devices, but all of them are insufficient in performances such as luminance, contrast, and color display, and have been put to practical use. Has not been reached.

Accordingly, the present applicant has proposed a novel display device in Japanese Patent Application Laid-Open No. 57-135590 as a device for achieving a flat display device using an electron beam.

This is because when the screen on the screen is vertically divided into multiple sections, an electron beam is generated for each section, and each line is deflected vertically for each section to display multiple lines Then, a television image is displayed as a whole.

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

This display element comprises a back electrode 1, a linear cathode 2 as a beam source, a vertical focusing electrode 3,
3 ', a vertical deflection electrode 4, a beam flow control electrode 5, a horizontal focusing electrode 6, a horizontal deflection electrode 7, a beam acceleration electrode 8, and a screen plate 9 are arranged, and these are flat glass bulbs (not shown). ) Is housed inside a vacuum. A linear cathode 2 as a beam source is stretched in a horizontal direction so as to generate an electron beam distributed linearly in a horizontal direction, and a plurality of such linear cathodes 2 (here, a plurality of linear cathodes 2 are arranged at appropriate intervals). (Only four of 2a to 2d are shown). In this embodiment, it is assumed that 15 are provided. Let them be 2a-2yo. These line cathodes 2 are formed by coating a surface of a tungsten wire of, for example, 10 to 20 μφ with an oxide cathode material for emitting thermoelectrons. These linear cathodes 2a to 2yo are heated so as to be able to generate a thermionic beam by increasing the current, and as will be described later, electrons are sequentially emitted from the linear cathode 2a for a certain period of time. It is controlled to emit a beam. The back electrode 1 suppresses the generation of an electron beam from another linear cathode 2 other than the linear cathode 2 controlled to emit the electron beam for a certain period of time, and directs the generated electron beam only in the forward direction. And push it out. This back electrode 1
May be formed by a coating of a conductive material adhered to the inner surface of the rear wall of the glass bulb. 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 10 opposed to each of the linear cathodes 2a to 2yo.
Remove through 10 and focus vertically. An electron beam for one horizontal line (360 picture elements) is simultaneously extracted. In the figure, only one of the horizontal sections is shown. The slits 10 may be provided with bars at appropriate intervals in the middle, or may be formed substantially as rows of through holes arranged in small numbers in the horizontal direction (intervals at which they almost touch). It may be. The vertical focusing electrode 3 'is similar.

A plurality of vertical deflection electrodes 4 are horizontally arranged at intermediate positions of the slits 10, each having conductors 13 and 13 ′ provided on the upper and lower surfaces of an insulating substrate 12. Have been. Then, a voltage for vertical deflection is applied between the opposing conductors 13 and 13 ′ to deflect the electron beam in the vertical direction. In this configuration, a pair of conductors
The electron beam from one line cathode 2 is deflected vertically by 13 and 13 'to a position corresponding to 16 lines. The sixteen vertical deflection electrodes 4 constitute fifteen conductor pairs corresponding to the fifteen linear cathodes 2, respectively.
The electron beam is deflected to draw 240 horizontal lines above.

Next, the control electrodes 5 are each formed of a conductive plate 15 having a slit 14 which is long in the vertical direction, and a plurality of the control electrodes 5 are arranged side by side in a horizontal direction with a predetermined interval. In this example
180 control electrode conductive plates 15a to 15n are provided (only nine are shown in the figure). Each of the control electrodes 5 takes out the electron beam by dividing it into two picture elements in the horizontal direction, and controls the passing amount according to a video signal for displaying each picture element. Therefore, if 180 conductive plates 15a to 15n for the control electrode 5 are provided, 360 picture elements can be displayed per horizontal line. In order to display an image in color, each picture element is displayed with phosphors of three colors of R, G, and B. Each control electrode 5 has R, G, and B for two picture elements.
Are sequentially added. Also, each of the 180 conductive plates 15a to 15n for the control electrode 5 has 180
A set (two picture elements per set) of video signals are added simultaneously,
One line of video is displayed at a time.

The horizontal focusing electrode 6 is constituted by a conductive plate 17 having a plurality of vertically long (180) slits 16 opposed to the slits 14 of the control electrodes, and the electron beam for each pixel divided in the horizontal direction. Are focused in the horizontal direction to form a thin electron beam.

A plurality of horizontal deflection electrodes 7 are provided at a position on both sides of the slit 16 in a vertical direction.
A six-stage horizontal deflection voltage is applied to each of the electrodes 18 and 18 'to deflect the electron beam for each picture element in the horizontal direction.
The G and B phosphors are sequentially irradiated to emit light.
In this configuration example, the deflection range is a width of two picture elements for each electron beam.

The accelerating electrode 8 is composed of a plurality of conductive plates 19 provided at the same position as the vertical deflection electrode 4 in the horizontal direction.
The electron beam is accelerated with sufficient energy to impinge on the screen 9 '.

The screen 9 is configured such that a phosphor 20 that emits light when irradiated with an electron beam is applied to the back surface of a glass plate 21 and a metal back layer (not shown) is added. The phosphor 20 is provided with two pairs of phosphors of three colors of R, G, B for one slit 14 of the control electrode 5, that is, for each one electron beam divided in the horizontal direction. Has been
It is applied in stripes in the vertical direction. In FIG. 3, broken lines drawn on the screen 9 indicate vertical divisions displayed corresponding to the plurality of line cathodes 2, respectively.
The dashed line indicates the horizontal division displayed corresponding to each of the plurality of control electrodes 5. In one section partitioned by these two, there are two picture elements of R, G, B phosphors 20 in the horizontal direction and 16 lines in the vertical direction, as shown in an enlarged manner in FIG. It has a width. The size of one section is, for example, 1 mm in the horizontal direction and 10 mm in the vertical direction.

In FIG. 3, the length in the horizontal direction is greatly extended in the vertical direction for easy understanding.

In this configuration example, the R, G, and B phosphors 20 correspond to one control electrode 5, that is, one electron beam.
Only pairs are provided, but of course one picture element or three
R, G, B video signals for one picture element or more than three picture elements are sequentially applied to the control electrode 5, and horizontal deflection is performed in synchronization with the control signal. You.

Next, a basic configuration of a drive circuit for displaying a television image on the display element will be described with reference to FIG. First, a driving portion for irradiating the screen 9 with an electron beam to emit a raster will be described.

A circuit for the power supply circuit 22 for applying a predetermined bias voltage (operating voltage) to the electrodes of the display element, the back electrode 1 -V _1, the vertical focusing electrode 3,3 'V ₃ in, V _3' , Horizontal focusing electrode 6
V _6, V ₈ in accelerating electrode 8, the screen 9 applies a DC voltage of V ₉ to.

Next, a composite video signal of a television signal is applied to an input terminal 23, and a vertical synchronizing signal V and a horizontal synchronizing signal H are separated and extracted by a sync separation circuit 24.

The vertical deflection driving circuit 40 includes a vertical deflection counter 25, a memory 27 for storing a vertical deflection signal, and a digital-analog converter 39 (hereinafter referred to as a DA converter). As an input pulse of the vertical deflection drive circuit 40, a vertical synchronization signal V and a horizontal synchronization signal H shown in FIG. 6 are used. The vertical deflection counter 25 (8 bits) counts the horizontal synchronization signal H reset by the vertical synchronization signal V. The vertical deflection counter 25 counts an effective scanning period (a period of 240H in this case) excluding the vertical blanking period in the vertical cycle, and this count output is supplied to the address of the memory 27. The memory 27 outputs vertical deflection signal data (here, 10 bits) corresponding to each address, and the DA converter 39 converts the data into v, v 'vertical deflection signals shown in FIG. In this circuit, there is a memory address that stores the vertical deflection signal corresponding to each line of 240H, and by storing regular data in the memory every 16H, 16 levels of vertical deflection signal can be obtained. it can.

On the other hand, the line cathode driving circuit 26 uses the vertical synchronization signal V and the output of the vertical deflection counter 25 to output a line cathode driving pulse [a
Yo] is created. FIG. 7A shows the relationship among the vertical synchronizing signal V, the horizontal synchronizing signal H, and the lower 5 bits of the water-time deflection counter 25. FIG. 7 (b) shows a 16
A method for generating a line cathode drive pulse [I 'to Y'] for each H will be described. In FIG. 7, LSB indicates the least significant bit, and (LSB + 1)
Means a bit one level higher than the LSB.

The first line cathode drive pulse [i '] is generated by using the vertical synchronization V and the output (LSB + 4) of the vertical deflection counter 25 as R-
It can be created by an S flip-flop or the like.
It can be obtained by transferring the line cathode drive pulse [i '] using the inverted (LSB + 3) output of the vertical deflection counter 25 as a clock. This drive pulse [a '
~ ヨ 'is inverted to a low potential only during each pulse period,
During the other periods, the pulse is replaced with a line cathode drive pulse [I-Y] of a high potential of about 20 volts and is applied to each of the line cathodes 2A-II.

Each of the line cathodes 2a to 2yo is heated by applying a current during the high potential of the drive pulse [i to yo] so that electrons can be emitted during the low potential period of the drive pulse [a to yo]. The heating state is maintained. As a result, 15 line cathodes 2a to 2
Electrons are emitted only during the 16H period in which the low-potential drive pulses [A to Y] are applied. During the period in which the high potential is applied, the potential is applied to the linear cathodes 2a to 2y higher than the potential at the position of the linear cathode 2 determined by the bias voltage applied to the back electrode 1 and the vertical focusing electrode 3. Line electrode 2
No electrons are emitted from (a) to (2). Thus, in the line cathode 2, during the effective vertical scanning period, electrons are sequentially emitted from the upper line cathode 2a toward the lower line electrode 2 for 16H periods.

The emitted electrons are pushed forward by the back electrode 1, pass through the opposed slits 10 of the vertical focusing electrode 3, are focused in the vertical direction, and become a plate-like electron beam.

Next, the linear cathode drive pulse (A to Y) and the vertical deflection signal v,
The relationship with v 'will be described with reference to FIG. The vertical deflection signals v and v 'change by 1H during the 16H period of each line cathode pulse [A to Y] and change in 16 steps. 'But both the center voltage and is V _4, v is sequentially increased, v' vertical signal v and v as slide into successively reduced, have been made to vary in opposite directions. These vertical deflection signals v and v 'are applied to the electrodes 13 and 13' of the vertical deflection electrode 4, respectively. As a result, the electron beams generated from the respective linear cathodes 2a to 2o are vertically shifted in 16 steps. The electron beam on the screen 9 as described above.
The raster for the lines is deflected so as to sequentially draw one line at a time from the top.

As a result, electron beams are emitted for 16 H periods in order from the upper one of the fifteen linear cathodes 2a to 2yo, and each electron beam is sequentially shifted from top to bottom within 15 vertical sections.
By being deflected line by line, the electron beam is vertically deflected one line at a time from the first line at the upper end to the 240th line at the lower end on the screen 9, and a raster of a total of 240 lines is drawn.

The electron beam vertically deflected in this manner is divided into 180 sections in the horizontal direction by the control electrode 5 and the horizontal focusing electrode 6 and extracted. FIG. 3 shows one of the sections. The passing amount of this electron beam is controlled by the control electrode 5 for each section, and the electron beam is focused in the horizontal direction by the horizontal focusing electrode 6 to form one thin electron beam.
R, G, and B phosphors 20 corresponding to two picture elements on the screen 9 are deflected in six stages in the horizontal direction by horizontal deflection means described below.
Are sequentially irradiated. FIG. 4 shows vertical and horizontal divisions. Each phosphor corresponding to 15a~15n the two pixels worth R of the control electrode 5, G, B to become for convenience of explanation, the other to the one pixel with R _1, G _1, B ₁ R _2, G _2, B ₂ to.

Next, the horizontal deflection driving circuit 41 includes a horizontal deflection counter (11 bits) and a memory storing a horizontal deflection signal.
29 and a DA converter 38. The input pulse of the horizontal deflection driving circuit 41 is synchronized with the vertical synchronizing signal V and the horizontal synchronizing signal H as shown in FIG.
A pulse 6H having a double repetition frequency is used.

The horizontal deflection counter 28 is reset by the vertical synchronizing signal V and counts the horizontal 6 times pulse 6H. This horizontal deflection counter is 28 times during 1H, 24 times during 1V.
0H × 6 / H = 1440 counts, and this count output is supplied to the address of the memory 29. The data of the horizontal deflection signal (here, 8 bits) corresponding to the address is output from the memory 29, and is converted by the DA converter 38 into a horizontal deflection signal such as h, h 'shown in FIG. . In this circuit 6 × 240
There is a memory address for storing a horizontal deflection signal corresponding to each line, and there is a regular 6 for each line.
By storing this data in the memory, a horizontal deflection signal of a six-step wave can be obtained in the 1H period.

The horizontal deflection signal is 'a, both of central voltage is V _7, h is sequentially decreased, h' a pair of horizontal deflection signals h and h that varies six stages as shown in FIG. 9 is sequentially increased Change in the opposite direction to each other. These horizontal deflection signals h and h 'are applied to the electrodes 18 and 18' of the horizontal deflection electrode 7, respectively. As a result, each electron beam divided in the horizontal direction is applied to the R, G, B, R, G, B of the screen 9 during each horizontal period.
The phosphors (R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , B ₂ ) are horizontally deflected so as to be sequentially irradiated with H / 6 at a time. Thus, in the raster of each line, the electron beam is R
_The phosphors 20 of ₁ , G ₁ , B ₁ , R ₂ , G ₂ , and B ₂ are sequentially irradiated.

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

Next, the modulation control portion of the electron beam will be described.

First, the composite video signal applied to the television signal input terminal 23 is applied to a color demodulation circuit 30, where the RY and BY color difference signals are demodulated, and the GY color difference signal is subjected to matrices synthesis. And these are combined with a luminance signal Y to produce R, G, B primary color signals (hereinafter referred to as R, G, B video signals).
Is output. These R, G, B video signals are applied to 180 sets of sample-and-hold circuit sets 31a to 31n. Each sample-and-hold circuits sets 31a~31n each for R _1, for G _1, for B _1, for R _2,
For G _2, has six sample and hold circuits for B _2.
Each of these sample-and-hold outputs is a memory group for holding
32a to 32n.

On the other hand, the reference clock oscillator 33 is constituted by a PLL (phase-locked loop) circuit or the like, in this embodiment generates a color subcarrier f _SC of 6 times the reference clock 6f _SC and 2 times the reference clock 2f _SC. The reference clock is controlled so as to always have a fixed phase with respect to the horizontal synchronization signal H. The reference clock 2f _SC is the deflection pulse generation circuit 42
Added to, to obtain a horizontal synchronizing signal signal switching pulses r ₁ 6 times per signal 6H and H / 6 of _{H, g 1, b 1,} r 2, g 2, b 2 of the pulse. On the other hand, the reference clock 6f _SC is applied to the sampling pulse generation circuit 34, where it is delayed by one clock cycle by a shift register, and the like.
c) During the effective horizontal scanning period (approx.
Number of sampling pulses R _a1 .about.B _n1 is sequentially generated, one transfer pulse t is generated thereafter. The sampling pulses R _{a1 to} B _n2 correspond to the respective picture elements when one line of an image to be displayed is divided into picture elements in the horizontal direction 360, and the positions thereof are always constant with respect to the horizontal synchronization signal H. Is controlled so that

The 1080 sampling pulses R _a1 .about.B _n2 respectively
Six are added to each of the 180 sample-and-hold circuit sets 31a to 31n, whereby each of the sample-and-hold circuit sets 31a to 3n is added.
1n is 2 when each line is divided into 180
Each video signal of picture elements R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , B ₂ is individually sampled and held. The sampled and held 180 sets of R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , and B ₂ video signals are simultaneously transmitted to the 180 sets of memories 32 a to 32 n by the transfer pulse t after one line of sample and hold is completed. , Where it is held for the next horizontal period. This retained R ₁ , G ₁ , B ₁ , R ₂ ,
The signals of G ₂ and B ₂ are applied to the switching circuits 35a to 35n. Each switching circuit 35a~35n has _{R 1, G 1, B 1} , R
₂ , G ₂ , and B ₂ , and a tri-state or analog gate having a common output terminal for sequentially switching and outputting them.

The output of the switching circuit 35a~35n is added to 180 pairs of pulse-width modulation (PWM) circuit 37A～37n, wherein the sample boards were _{R 1, G 1, B 1} , R 2, G 2, B 2 video The reference pulse signal is pulse-width modulated according to the magnitude of the signal and output. It is desirable that repeated period of the reference pulse signal is intended the signal switching pulses r ₁ of, g _1, b _1, r _2, g _2, b sufficiently smaller than the _second pulse width, for example, 1: 10 1: 100
The degree is used.

The outputs of the pulse width modulation circuits 37a to 37n are used as control signals for modulating the electron beam by the control electrodes 5 of the display element.
Each of the 180 conductive plates 15a to 15n is individually added.
Switching pulse r ₁ each switching circuit 35a~35n is applied from the switching pulse generation circuit _{36, g 1, b 1,} r 2,
Switching control is performed simultaneously by g ₂ and b ₂ . The switching pulse generation circuit 36 is controlled by the signal switching pulses r ₁ , g ₁ , b ₁ , r ₂ , g ₂ , b ₂ from the deflection pulse generation circuit 42 described above, and divides each horizontal period into six. by H / 6 switches the switching circuit _{35a~35n, R 1, G 1,} B 1, R 2, G 2, and sequentially outputs the time division of each video signal of B _2, the pulse width modulation circuit 37a~37n The switching signals r ₁ , g ₁ , b ₁ , r ₂ , g ₂ , b ₂ are generated so as to be supplied.

It should be noted here that the switching circuits 35a to 35n
Supply switching of the video signals of R ₁ , G ₁ , B ₁ , R ₂ , G ₂ , B _{2 at} , and the electron beams R ₁ , G ₁ , B ₁ , R ₂ , by the horizontal deflection drive circuit 41
That is, the synchronous control is performed such that the irradiation switching horizontal deflection of the G ₂ and B ₂ phosphors completely coincides both in tie timing and in order. Thereby, when the electron beam is irradiated on the R ₁ phosphor, the irradiation amount of the electron beam is controlled by the R ₁ video signal, and G ₁ , B ₁ , R ₂ , G ₂ ,
B ₂ is similarly controlled, and R ₁ , G ₁ , B ₁ , R ₂ ,
G _2, B ₂ will be light emission of each phosphor are controlled by the _{R 1, G 1, B 1} , R 2, G 2, B 2 of the video signal of the picture element, each picture element of the input Light emission is displayed according to the video signal.
This control is performed simultaneously for 180 sets (one picture element each) of one line to display an image of 360 picture elements for one line, and further for the 240 minute line, it is sequentially performed from the upper line to the screen 9. Will be displayed on the screen.

The above operations are repeated for each field of the input television signal, and as a result, a moving picture television image is displayed on the screen 9 in the same manner as a normal television receiver.

In addition, due to the deterioration of the electron beam generating ability of the line cathode 2 with time, the electron beam generating ability is reduced by the back electrode 1, the line cathode 2,
The geometrical positional relationship and potential distribution of the vertical focusing electrodes 3, 3 ', and the amount of emission from the electron beam source, which is generated by the linear cathode 2 and is limited by space charge electrons distributed around the linear cathode 2, are increased. From a turning state (hereinafter referred to as a space charge limiting region), the amount of electron beam generated by the line cathode 2 falls below the amount determined by the space charge electrons, and the temperature of the line cathode 2 and the line cathode 2
, Ie, a state in which all the electron beams generated by the linear cathode 2 are emitted (hereinafter, this is referred to as a temperature-limited region). For this reason, the variation in the local electron beam generating capability of the linear cathode 2 appears on the screen, and the uniformity of the luminance of the screen is impaired. Therefore, as shown in FIG. 10, a change in the amount of the electron beam flowing into the vertical focusing electrode 3 'is detected by the electron beam amount detection circuit 51, and based on the detection result, the voltage control circuit 52 controls the line cathode drive. The power supply voltage applied to the circuit 26 is increased to raise the temperature of the linear cathode 2 so that the linear cathode 2 always operates in the space charge limited region.

Problems to be Solved by the Invention However, in the image display device having the above-described configuration, the line cathode driving current increases steadily due to the deterioration over time of the electron beam generating ability of the line cathode, and accordingly, Since the temperature of the line cathode also increases, the life of the line cathode is shortened.

In view of the above problems, the present invention operates a limiter safety circuit when a line cathode driving current reaches a certain level (a limit level that does not shorten the life of the line cathode), fixes the line cathode driving current, and fixes the line cathode driving current. Of the image display device, that is, the life of the image display device.

Means for Solving the Problems In order to achieve this object, the image display device of the present invention comprises:
The amount of increase in the line cathode drive current is determined by detecting the potential output from the voltage control circuit, and the input from the electron beam amount detection circuit to the voltage control circuit is fed back to reduce the increase in the line cathode drive current. It has a configuration of fixing at a fixed level.

Operation The present invention prevents the linear cathode drive current from increasing remarkably and the temperature of the linear cathode itself from becoming too high, thereby shortening the life of the linear cathode.

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 limiter safety circuit of an image display device according to an embodiment of the present invention.

In FIG. 1, reference numeral 60 denotes a limiter safety circuit which detects changes in the output voltage from the voltage control circuit 52 by resistors 61, 62, 63, 64, 6
5, the transistors 67 and 68, and the Zener diode 70, detect and operate the limiter circuit including the resistor 66 and the transistor 69 to control the input voltage from the electron beam amount detection circuit 51 to the voltage control circuit 52. Be composed.

The operation of the image display device configured as described above will be described below with reference to FIGS.

2 (a) shows the detection voltage from the electron beam amount detection circuit 51, and FIG. 2 (b) shows the line cathode drive voltage output from the voltage control circuit 52. Both (a) and the linear cathode drive voltage (b) show a constant potential. Next, the potential of the detection voltage (a) rises when the temperature enters the temperature limit region due to the deterioration of the linear cathode 2 over time, and accordingly, the potential of the linear cathode drive voltage (b) also rises. However, when the linear cathode drive voltage increases significantly, the temperature of the linear cathode itself rises too much and shortens the life of the linear cathode. The transistor 67 in FIG. 1 is turned on, and accordingly, the transistor 68 is also turned on. When the transistor 68 is turned on, an input potential is applied to the base of the transistor 69, so that the transistor 69 is also turned on. Therefore, the detection current from the electron beam amount detection circuit 51 is supplied to the transistor 69.
And operates so as to suppress an increase in the detection voltage of the electron beam amount detection circuit 51, that is, the line cathode drive voltage from the voltage control circuit 52.

Since the voltage across the resistor 65 is used as the base input voltage of the transistor 69, the limiter safety circuit 60 operates in a negative feedback loop, and the line cathode drive voltage from the voltage control circuit 52 can be kept constant thereafter. .

Effect of the Invention As described above, the present invention uses a line-cathode drive circuit by a limiter safety circuit to prevent the line-cathode drive current from unconditionally increasing due to the deterioration of the electron beam generation ability of the line cathode over time. The increase in current can be fixed at a certain level, and the life of the linear cathode can be extended.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a limiter safety circuit of an image display device according to an embodiment of the present invention, and FIG. 2 is an output voltage from an electron beam amount detection circuit and a voltage control circuit by operation of the limiter safety circuit of FIG. FIG. 3 is an exploded perspective view showing a basic configuration of a conventional image display device, and FIG. 4 is an enlarged phosphor surface showing a minimum unit configuration of the present image display device on a screen. FIG. 5, FIG. 5 is a block diagram of a drive circuit in the device, FIG. 6 is a waveform diagram showing a correlation between a vertical deflection voltage and a horizontal synchronization signal, FIG. 7 is a waveform diagram showing various timings, and FIG. FIG. 9 is a waveform chart showing the relationship between the cathode drive pulse, the vertical deflection signal, and the horizontal deflection signal. FIG. 9 is a waveform chart showing the correlation between the horizontal deflection voltage and the horizontal synchronization signal.
FIG. 1 is a block diagram of a conventional electron beam amount detection circuit and a voltage control circuit. 60 …… Limiter safety circuit, 61 …… Resistance, 62 …… Resistance, 63
…… resistance, 64 …… resistance, 65 …… resistance, 66 …… resistance, 67…
... transistor, 68 ... transistor, 69 ... transistor, 70 ... Zener diode.

Claims (1)

(57) [Claims] 1. A plurality of linear cathodes constituting an electron beam source;
A focusing electrode for focusing the electron beam from the linear cathode,
A deflection electrode for deflecting the electron beam in the vertical and horizontal directions, a screen that emits light when irradiated with the electron beam, and a television signal that controls the amount of the electron beam and controls the brightness on the screen. In an image display device including an electron beam control electrode,
An electron beam amount detector for detecting an amount of the electron beam flowing into the focusing electrode; and a line cathode drive circuit for controlling an amount of the electron beam emitted from the line cathode in accordance with an output signal of the electron beam amount detector. Voltage control means for controlling a voltage to be applied, and a limiter safety circuit for controlling a voltage from the electron beam amount detection means to the voltage control means when an output voltage of the voltage control means exceeds a certain level. An image display device characterized by the above-mentioned.