JPS61116477A - Image display device - Google Patents

Abstract

PURPOSE:To suppress the vibration of a line cathode ray by causing the line cathode ray to receive electric force corresponding to a speed from an electric field where the line cathode ray lies and enlarging equivalently the attenuation ratio of a vibration system produced by the line cathode ray. CONSTITUTION:A line cathode ray drive output circuit 53 outputs a pulse signal going to a low level during a horizontal blanking period based on a horizontal pulse. This output pulse signal is applied to an integrator together with a line cathode ray drive pulse (a) from a line cathode ray drive circuit 26, and the output is applied to a line cathode ray 2a. At this time, the line cathode ray drive pulse A impressed to the line cathode ray 2a is modulated so that its horizontal blanking period can go to a low level during a line cathode ray heating period, and an electron beam is emitted at every horizontal blanking period at a low level during the heating period from the line cathode ray 2a. In such as way the electron beam is emitted from the line cathode ray 2a at every horizontal blanking period during the line cathode ray heating period, and the electron beam stream at this time is detected as an electric current by a vertical focusing electrode 3. Thus the vibration of the line cathode ray 2a is detected, and the vibration of the line cathode ray 2a is prevented by subsequent circuits.

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. The present invention relates to an apparatus for displaying a plurality of lines by vertically deflecting each electron beam to display a television image as a whole.

Conventional configuration and its problems Traditionally, cathode ray tubes have been used as display elements for displaying color television images, but conventional cathode ray tubes have a very long depth compared to the screen size. It was impossible to create a thin television receiver. Furthermore, as flat display elements, EL display elements, plasma display devices, liquid crystal display elements, etc. have recently been developed.

All of them are insufficient in terms of performance such as brightness, contrast, and color display, and have not yet been put into practical use.

Therefore, the present applicant proposed a new display device in Japanese Patent Application No. 56-20618 (Japanese Unexamined Patent Publication No. 57-185590) to construct a flat display device using electron beams.

This method generates an electron beam for each division when the screen is vertically divided into multiple divisions, and deflects each beam in the vertical direction for each division. A device was invented that displayed the lines of 6 and displayed the 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) +a+, a vertical deflection electrode (4), and a beam flow control electrode (5). ), horizontal focusing electrode (
6) It consists of a horizontal deflection electrode (7), a beam acceleration electrode (8), and a screen (9), which are housed inside a flat glass bulb (not shown) that is evacuated. ing. Line cathode as beam source (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 arranged vertically at appropriate intervals.
2d) only four are shown). In this example, it is assumed that 15 are provided. These (2a
) to (20). These wire cathodes (2) are constructed by coating the surface of a 10-20 μm tungsten wire with an oxide cathode material for thermionic emission. These line cathodes (2a) 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 (2a) to (2o) 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 of conductive material applied to the inner surface of the rear wall of the glass bulb. Moreover, a one-plane electron beam emitting cathode may be used instead of the back electrode (1) and the line cathode (2).

The vertical focusing electrode (3) is a conductive plate CL having a horizontally long slit α1 facing each of the line cathodes (2a) to (20), and directs the electron beam emitted from the line cathode (2) through the slit θG. and vertically focused. Electron beams for one horizontal line (860 pixels) are taken out at the same time. In the diagram.

Of these, only one section in the horizontal direction is shown.

The slit O0 may be provided with crosspieces at appropriate intervals in the middle, or it may be a row of through holes arranged horizontally at small intervals (nearly touching intervals). It may also be configured as a slit. The vertical focusing electrodes ('3 are also similar).

Vertical deflection electrodes (a plurality of vertical deflection electrodes are arranged horizontally in the middle of each of the above-mentioned slits QO, and conductors σ:j6 are placed on the upper and lower surfaces of the insulating substrate (6), respectively.
It consists of a set of Then, a vertical deflection voltage is applied between the three opposing conductors to deflect the electron beam in the vertical direction.

In this embodiment, the electron beam from one line cathode (2) is vertically deflected to a position corresponding to 16 lines by a pair of conductor gifts. and 16 vertical deflection electrodes (4)
1 corresponding to each of the 15 line cathodes (2) by
Five pairs of conductors are constructed and ultimately deflect the electron beam to draw 240 horizontal lines on the screen (9).

Next, the control electrode (5) is composed of conductive plates αG each having a long slit α in the vertical direction.

A plurality of them are arranged in parallel in the horizontal direction at predetermined intervals. In this example, 180 control electrode conductive plates (15-1) to (
15-n) is provided. (Only 9 lines are shown in the figure). Each of the control electrodes (5) separates and extracts the electron beam into two picture elements in the horizontal direction, and controls the amount of electron beam passing therethrough in accordance with a video signal for displaying each picture element. Therefore, the conductive plate (15) for the control electrode (5)
-1) to (15-n) are installed horizontally 1
860 picture elements can be displayed per line. In addition, in order to display images in color, each picture element is R, G, B
Each control electrode (5)
R, G, and B video signals for two picture elements are sequentially added to the . In addition, 180 control electrodes (5) conductive plates (15-
1) to (15-n), each line has 18
0 sets (2 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 αQ (180 slits) opposite to the slit σ4 of the control electrode (5), each of which is divided horizontally. The electron beams for each picture element are focused horizontally into a narrow electron beam.

The horizontal deflection electrode (7) is composed of a plurality of conductive plates (0') arranged vertically on both sides of the slit αQ. A stepwise horizontal deflection voltage is applied to horizontally deflect the electron beam of each pixel, and the screen (9
), the two sets of R, G, and B phosphors are sequentially irradiated to emit light. In this example, the deflection range is two picture elements wide for each electron beam.

The accelerating electrode (8) is composed of a plurality of conductive plates σ1 installed horizontally in the same position as the vertical deflection electrode (4), and it screens the electron beam with sufficient energy (
9) Accelerate so that it collides with

The screen (9) has a phosphor (4) that emits light when irradiated with an electron beam applied to the back surface of the glass plate.

Further, a metal back layer (not shown) is added. The phosphor (a) is attached to one slit σ of the control electrode (5), that is, to each slit σ divided in the horizontal direction.
Two pairs of eight-color phosphors, R, G, and H, are provided for each electron beam of the book, and are applied in stripes in the vertical direction. In FIG. 1, the broken lines drawn on the screen (9) indicate vertical divisions displayed corresponding to the plurality of line cathodes (2), and the two-dot chain lines indicate the divisions in the vertical direction that are displayed corresponding to the plurality of line cathodes (2). ) shows the horizontal divisions displayed corresponding to each of them. As shown in the enlarged view in Figure 2, one section partitioned by these two has R, G, and H phosphors (A) for two pixels in the horizontal direction, and one in the vertical direction.
It has a width of 6 lines. The size of one section is
For example, one horizontal direction is 1 mm and one vertical direction is 9 mm.

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

Also, in this example, only one pair of R, G, and H phosphors (1) for two picture elements are provided for one control electrode (5), that is, for one electron beam, but of course , one picture element or three or more picture elements may be provided, in which case R, G, and B video signals for one picture element or eight picture elements or more are sequentially applied to the control electrode (5), Horizontal deflection is performed in synchronization with this.

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 description will be given of the driving part that irradiates the screen (9) with an electron beam to emit raster light.

The power supply circuit (A) is a circuit for applying a predetermined bias voltage (operating voltage) to each electrode of the display element, and is connected to the rear surface 111E.
Pole (1) R: let -V+, vertical jf% flux 11E Pole (3) (31 niH V3, V3' - V6 for the horizontal focusing electrode (6), v8. for the accelerating electrode (8).
A DC voltage of V9 is applied to the screen (9), a composite video signal of a television signal is applied to the input terminal (C), and the vertical synchronization signal V and horizontal synchronization signal H is separated and extracted.

The vertical deflection drive circuit (to the vertical deflection counter).

It is composed of a memory (a) for storing vertical deflection signals, a digital-to-analog converter (hereinafter referred to as a DA converter). As input pulses to the vertical deflection drive circuit (to), a vertical synchronizing signal V and a horizontal synchronizing signal H shown in FIG. 4 are used. The vertical deflection counter (8 bits) is reset by the vertical synchronizing signal V and counts the horizontal synchronizing signal H. For this vertical deflection counter), the effective scanning period excluding the vertical retrace period of the vertical period (in this case, 24
This count output is supplied to the address of the memory (c). The vertical deflection signal data (here, 8 bits) corresponding to each address is output from the memory wire, and the data is sent to the D-A converter (2) as shown in Fig. 4 (
It is converted into vertical deflection signals of v and v' shown in FIG. 8(b)D). This circuit has memory addresses for storing vertical deflection signals corresponding to each line for 240H, and by storing regular data in the memory every 16H, it is possible to obtain 16 levels of vertical deflection signals. can.

10,000, the line cathode drive circuit (e) uses the vertical synchronization signal V and the output of the vertical deflection counter (c) to generate the line cathode drive pulse a.
~Create 0. FIG. 5(a) shows the relationship between the vertical synchronizing signal V, the horizontal synchronizing signal H, and the lower five bits of the repetition deflection counter (c). FIG. 5(b) shows a method of creating line cathode drive pulses a'~0'' every 16H using these signals. In FIG. 5, LSB indicates the lowest bit;
(LSB+1) means the bit one higher than the LSB.

The first line cathode drive pulse a'' is generated using the vertical synchronization signal V and the output (LSB+4) of the vertical deflection counter).
-Can be created using S flip-flops, etc.

The line cathode drive pulses b' to 0'' can be obtained by using a shift register to transfer the line cathode drive pulse a' using the inverted version of the output CLSB+8> of the vertical deflection counter (c) as a clock. This driving pulse l~
O' is inverted and kept at a low potential only during each pulse period, and converted into a line cathode drive pulse a''o that is at a potential of about 20 volts during other periods (Fig. 8(b) E).
, each line cathode (2a) to (2o) +21 is added.

Each line cathode (2a) to (2o) receives its driving pulse a ”
A current is passed through it during the high potential of o to heat it, and the heated state is maintained so that electrons can be emitted during the low potential period of 1 drive pulse a to 0. As a result, 15 Hi & Extreme (
Electrons are emitted from 2a) to (2o) only during the 16H period when a low potential drive pulse a"-"o is applied to each of them. During periods when high potential is not applied, the back electrode (
1) and the vertical focusing electrode (3), which is higher than the potential at the position of the line cathode (2) determined by the bias voltage applied to the vertical focusing electrode (3). is positive, the line cathodes [2a) to (2
No electrons are emitted from o). Thus.

At the line cathode (2) during the effective vertical scanning period.

Electrons are sequentially emitted from the upper line cathode (2a) to the lower line cathode (2o) every 16H period. The emitted electrons are pushed out to the front by the back electrode (1).

The electron beam passes through the opposing slits OQ of the vertical focusing electrode (3), is focused in the vertical direction, and becomes a flat electron beam.

Next, the relationship between the line cathode drive pulses a to 0 and the vertical deflection signal, vl, will be explained using FIG. Figure 6 (a
) is a waveform diagram of a linear cathode drive pulse, (b) is a waveform diagram of a vertical deflection signal, and (c) is a waveform diagram of a horizontal deflection signal. 6th
The vertical deflection signals v, v" in FIG. 6(b) change by IH during the 16H period of each line cathode pulse a to 0 in FIG. 6(a) and change in 16 steps.The vertical deflection signals V and V Both `` and `` have a center voltage of v4, ``■'' increases sequentially, and ``■'' sequentially decreases, so that they change in opposite directions.These vertical deflection signals V and V' are are added to electrodes (to) and (3) of vertical deflection electrode (4), respectively,
As a result, the electron beams generated from each of the line cathodes (2a) to (2o) are vertically deflected in 16 steps.
As mentioned above, one electron beam is deflected on the screen (9) so that a raster of 16 lines is drawn one line at a time from the top.

As a result of the above, electron beams are emitted sequentially from the upper part of the 15 line cathodes (2a) to [20] for a period of 16H, and each electron beam is sequentially emitted one line from the upper part to the lower part within the 15 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 0 line, and a star is drawn on a total of 240 lines.

The vertically deflected electron beam is connected 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 1, one of them
The classification is shown. The amount of electron beam passing through each section is controlled by a control electrode (5), and is horizontally focused by a horizontal focusing electrode (6) into a single narrow electron beam by horizontal deflection means described next. The light is deflected in six steps in the direction and sequentially irradiates each of the R, G, and B phosphors (1) for two picture elements on the screen (9). Second
The figure shows vertical and horizontal divisions. Control electrode (
The phosphors corresponding to each of (15-1) to C15-n) in [5] are R, G, and B for two picture elements, but for convenience of explanation, one picture element is set to RH+ + + 13+ and the other is R2.
+ G2' + B2.

Next, the horizontal deflection drive circuit (b) is a horizontal deflection device consisting of a horizontal deflection counter (c) (11 bits), a memory fi storing horizontal deflection signals, and a DA converter (to). The input pulses of the drive circuit 04) are synchronized with the vertical synchronizing signal V and the horizontal synchronizing signal H, as shown in FIG.

A pulse 6H having a repetition frequency six times that of the horizontal synchronizing signal H is used. The horizontal deflection counter (c) is reset by the vertical synchronizing signal V and counts the horizontal six-fold pulse 6H. This horizontal deflection counter (c) Lt I H 6 times, IV (7) 240HX 6/H=1440
This count output is supplied to the address of ) in memory. Memory 4 outputs horizontal deflection signal data (8 bits in this case) according to the address, and D
-A converter (to) converts it into a horizontal deflection signal h' as shown in FIG. 7 (FIG. 8(b)C). 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, a 6-step waveform is generated during the IH off period. horizontal deflection signals can be obtained.

As shown in FIG. 7, this horizontal deflection signal is a pair of horizontal deflection signals h' that change in six steps, both of which have a center voltage of v7, and h gradually decreases to hh.

change in opposite directions so that they increase sequentially.

These horizontal deflection signals h'' are the horizontal deflection electrodes (
7) is added to the electrode (g) and θ-'). As a result, each horizontally segmented electron beam passes through the R, G, B, R, G of the screen (9) during each horizontal period.

B (B+, Gl, B+, R2, G2.
It is horizontally deflected so that the phosphor of B2) is sequentially irradiated for H/6 periods.

Thus, in each line raster, the horizontal direction 18
The electron beam for each section of 0 is R1+Gl+Bl
*R2, G2. Each phosphor (e) of B2 is sequentially irradiated.

Therefore, for each horizontal section of each line, the electron beam is set to B+,
By modulating with the video signals of Gl, Bl + R2 + G2 + B2, 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 (c) is applied to the color demodulation circuit (to), where the RY and B-Y color difference signals are demodulated.

G-Y color difference signals are matrix-synthesized, and further.

These are combined with the luminance signal Y to output R, G, and B primary color signals (hereinafter referred to as R, G, and B video signals).

These R, G, and B video signals are applied to 180 sets of sample and hold circuits (81-1) to (81-n).

Each sample hold circuit (81-1) to (81-n) is for R1, IB for Gl, + iG2 for R2.
for.

It has six sample and hold circuits for B2.

These sample and hold outputs are stored in memory (
82-1) to (82-n).

The reference clock oscillator) is constituted by a PLL (phase-locked loop) circuit, etc., and in this example generates a reference clock 6 fsc that is six times the color subcarrier fsc and a reference clock 2 fsc that is twice the color subcarrier fsc.

The reference clock is controlled to always have a constant phase with respect to the horizontal synchronization signal H. Reference clock 2
fsc is added to the deflection pulse generation circuit, and a signal 6H, !, which is six times the horizontal synchronizing signal H, is applied. : Signal switching pulse every H/6 rl + R3+ I)1 + r31 R2+
A pulse of B2 (FIG. 8(b)B) is obtained. -10,000 reference clock 6 fsc is the sampling pulse generation circuit (
is added to the horizontal period (68, 5
effective horizontal scanning period (approximately 50 μsec)
c) 1080 sampling pulses R11 during
1GII + Bll + R12* G12 + B+
2 + R211G21 + B21 lR221G2
21B22ゝRn+, Gn+, Bn+, Rn2.
Gn2. Bn+ (Fig. 8 (bl)) are generated sequentially, and then one transfer pulse t is generated. These sampling pulses Ro to Bn2 divide one line of the image to be displayed into 860 picture elements in the horizontal direction. The position of each picture element is controlled so that it is always constant with respect to the horizontal synchronizing signal H.

17) 1080 sampling pulses R11 to Bn
180 sets of sample hold circuits (81-
1) to (81-n), and as a result, each sample hold circuit (81-1) to (81-n) has two picture elements each when one line is divided into 180 pieces. R1+ Gl + Bl, R2+ G2 +
Each of the 82 video signals is individually sampled and held. The sample held 180 pairs of R1+
The video signal of Gl * Bl + R2 + G 2 + B2 is transferred to 180 sets of memories (82-1) to (82-n) as a pulse t after completing the sample hold for one line.
are transferred all at once and held here for the next horizontal period. This retained B+ r GI , B+
*R2+G2 *B2 signal is switching circuit C
85-1) to (85-n). Switching circuits (85-1) to (85-n) are R1 and GI, respectively.
, Bll R21G21 B2CD It is composed of a tri-state or analog gate having individual input terminals and a common output terminal that sequentially switches and outputs them.

The output of each switching circuit (85-1) to (85-n) is 180 sets of pulse width modulation (PWM) circuit C87-1)
~C87-n>, where sample-and-hold R1 + Gl + Bl * 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 rl + gl
+ I) It is desirable that the pulse width is sufficiently smaller than the pulse width of I + r2 + R2 + b2. For example,
A ratio of about 1:10 to 1:100 is used.

The outputs of the pulse width modulation circuits (87-1) to (87-n) are used as control signals for modulating the electron beam to the 180 conductive plates (15-1) to the control electrode (5) of the display element.
(15-n) respectively. Each of the switching circuits (85-1) to (85-n) is simultaneously controlled to switch by a switching pulse '+gl+bl+r2+g2+b2 applied from the switching pulse generating circuit (7). The signal switching pulse rl l gl + +) 1 # r2
+g2+b2, each horizontal period is controlled by 6
Divided into H/6 switching circuits (85-1) to (
85-n) i R1+ GI HBl r R
2* G2 + B2 video signals are time-divided and sequentially output, and a switching signal rl r gl + ble is provided so as to supply the video signals to the pulse width modulation circuits (87-1) to (87-n).
Generate r2+g2+b2.

What should be noted here is that the switching circuit (85-1
) to (85-n), R1, Gl r Bl +
R2r G2 + B2 video signal supply switching,
Electron beam R1m Gj + by horizontal deflection drive circuit H
The irradiation switching horizontal deflection of B+ p R2 * G2 r B2 to the phosphor is synchronously controlled so that it completely matches both the timing and the order. Thereby, when the R1 phosphor is irradiated with the electron beam, the irradiation amount of the electron beam is controlled by the R1 video signal.

G3# Blt R2g G2 p B2 is similarly controlled.

B+, G1 of each picture element. B+, R2+ G2
+ B2 The light emission of each party light is R1+ Gl m of that picture element
Each picture element is controlled by a video signal of Bl+R2+G2*B2, and each picture element is displayed by emitting light according to the input video signal. Such control is 1
This is performed simultaneously for 180 lines (2 pixels each) to display an image of 860 pixels per line, and then sequentially for 240H lines starting from the upper line. Two images will be displayed.

and one or more such operations are performed on one or more of the input television signals.
The result is repeated for each field.

A moving television image is projected on the screen (9) in the same way as a normal television receiver.

The problem with the image display device configured as above is that it uses a wire cathode (2) stretched in a vacuum, so the wire cathode (2) tends to vibrate, and furthermore, because the damping coefficient is small, once the wire begins to vibrate, The cathode (2) takes several minutes to stop vibrating.
This is a point that requires several tens of minutes. As is clear from the structure of the image display device, when the position of the line cathode (2) changes due to vibration, the position and brightness of the electron beam reaching the screen (9) change, significantly deteriorating the image quality.

Purpose of the Invention The present invention aims to prevent image quality deterioration due to vibration of a line cathode.
The purpose is to prevent the vibration of the line cathode itself.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has a wire cathode stretched in a vacuum, a means for electrically detecting the position of the wire cathode due to vibration, etc., and a means for detecting the detected position of the wire cathode. It is equipped with means for converting into a signal corresponding to the speed of vibration, and means for applying the signal corresponding to the speed as a voltage to the wire cathode itself, and the wire cathode is connected to an electric field in which the wire cathode is placed to generate an electric force corresponding to the speed. By making the wire cathode receive a large amount of radiation, the damping constant of the vibration system created by the wire cathode is equivalently increased, thereby suppressing the vibration of the wire cathode.

The basic method for preventing the vibration of the line cathode is explained using the first-order equation. Generally, a linear vibration phenomenon is expressed by equation (1).

Here, ψ is the displacement, γ is the damping constant, ω is the natural frequency, and F
is proportional to the external force In the above equation (1), the second term on the left side is proportional to the vibration speed of the line cathode, and the larger the damping constant γ, the faster the damping, and the smaller the vibration amplitude itself. In the present invention, in the electric field created by the back electrode and the vertical focusing electrode that sandwich the wire cathode, the electric force received by the wire cathode changes as shown in the second term on the right side of the following equation (2) (for the 6-wire cathode). This changes the voltage in proportion to the speed of vibration.

Here, A is a proportionality constant, and A correction ψ is the electric force received by the wire cathode, which is the reduction constant γ as shown in the first-order equation (3).
is increased to an equal value, and image quality deterioration due to vibration of the line cathode can be prevented.

Note that Equation (3) is a modification of Equation (2), and the attenuation constant is increased to (γ+A).

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 8th
In the figure, (7) is a current-voltage conversion circuit that detects the vibration of the wire cathode (2) as a current flowing into the vertical focusing electrode (3) and converts the current value into a voltage, and i5]l is the current-voltage conversion circuit described above. A sample-and-hold circuit that interpolates the output voltage of the conversion circuit ■ using horizontal pulses.

4 is a phase conversion circuit for making the output of the sample hold circuit (c) proportional to the vibration speed of the wire cathode (2); 63) is a phase conversion circuit for making the output of the sample hold circuit (c) proportional to the vibration speed of the wire cathode (2); This is a line cathode drive output circuit for applying voltage to the cathode (2).

It has output terminals corresponding to the number of line cathodes (2).

Next, the operation will be further explained using FIGS. 9 and 10. Here, as an example, a case will be described in which vibration of the line cathode (2a) is detected and the vibration is suppressed. The line cathode drive output circuit outputs a pulse signal that is at a low level during the horizontal retrace period based on the horizontal pulse. This output pulse signal is applied to an integrator (not shown) together with the line cathode drive pulse a from the line cathode drive circuit (c) in FIG. 3, and its output is applied to the line cathode (2a). At this time, the line cathode drive pulse A applied to the line cathode (2a) becomes as shown in FIG. 9 (5), and during the electron beam emission period, the line cathode drive pulse A from the line cathode drive circuit (c) It is the same low level as , but it is modulated so that the horizontal retrace period becomes low level during the line cathode heating period. Therefore, the line cathode (2
From a), an electron beam is emitted every low-level horizontal retrace period during the heating period. In this way, an electron beam is emitted from the line cathode (2a) during each horizontal retrace period during the line cathode heating period, and the electron beam flow at this time is detected as a current by the vertical focusing electrode (3).
This allows the vibration of the line cathode (2a) to be detected, and based on this detection signal, the subsequent circuit uses the line cathode (2a).
) to prevent vibration. In addition, in contrast to this line cathode drive pulse AC (Fig. 9(A)), the drive pulses applied to the other line cathodes (2b) to (2o) reach a high level during the horizontal retrace period in the electron beam emission period. A pulse is created such that the electron beam is not emitted during the horizontal retrace period, that is, the detection period during the electron beam emission period. Line cathode (2b) (2
Figure 9 shows the waveforms of driving pulses B and C applied to c).
(See Q.

The m original waveform flowing to the vertical focusing electrode (3) based on the above line cathode drive pulse AC@9 (4)) is shown in Figure 10 (A). This current value is converted into a voltage value by a current-voltage conversion circuit, and further interpolated using a horizontal pulse by a sample-and-hold circuit (5υ), and the output voltage shown in Figure 10 is output at its output terminal. This voltage waveform (see Figure 10) corresponds to the position change due to vibration of the wire cathode (2a).In other words, when the wire cathode (2a) is displaced toward the back electrode (1), vertical focusing occurs. Figure 10 (
The current shown in FIG. 10(a) becomes small, and when the electrode is displaced toward the vertical focusing electrode (3), the current shown in FIG. 10(a) becomes large. Therefore, the voltage waveform in FIG. 10(b) also corresponds to the position (displacement) of the wire cathode (2a).

Next, the phase of the voltage shown in Fig. 10 (b) is rotated by 90° by the phase conversion circuit β4, and converted into a voltage waveform (e'9 in Fig. 1O) corresponding to the vibration speed of the line cathode (2a). , is added to the line cathode drive output circuit. Then, the line cathode drive output circuit applies a drive pulse AC (Fig. 9 (8)) which becomes low level during the horizontal retrace period of the line cathode heating period as described above to the line cathode (2a). The other line cathodes (2b), (2c) ~ are provided with driving pulses B, C which are at a high level during the horizontal retrace period of the electron beam emission period.
(@Figure 9 (8) (C))~ are applied, and at the same time, while the drive pulse A is at a high level, the voltage waveform of Figure 10 (C) is superimposed and applied to the back electrode (υ and vertical In the electric field created by the focusing electrode (3), the first
A pulse signal is generated to apply an electric force corresponding to the voltage waveform shown in Fig. 0 (c). Accordingly, Figure 9 (2)
As shown in , the waveform of the drive pulse A changes, and the line cathode (
2a) The vibrations are suppressed.

The vibrations of the line cathodes other than the line cathode (2a) can also be suppressed in one time division by the same method as above.

As another embodiment, a circuit that simultaneously suppresses the vibration of two or more line cathodes will be described. For simplicity, use a wire cathode (
A circuit for simultaneously suppressing vibrations 2a) and (2b) will be explained using FIGS. 11 and 12. Line cathode (
The pulse A (Fig. 12 (A)) that drives the line cathode (2a) is a pulse that alternately repeats high and low levels during each horizontal retrace period even during the electron beam emission period. ) driving pulse B (Fig. 12 (
B)) is a pulse in which the drive pulse A (FIG. 12 (2)) becomes a low level in the line cathode heating period and becomes a high level in the horizontal retrace period during the electron beam emission period;
Other line cathode drive pulses C (Fig. 12 (Q) and below are pulses that are low level during the line cathode heating period of drive pulses A and B during the electron beam emission period, and are high level during the horizontal retrace period. and line cathodes (2a) (2b), respectively.
) and each of the other line cathodes (2c) to (2o).

At this time, the current flowing through the vertical concentration electrode (3) alternately appears as the current emitted from the line cathodes (2a) and (2b) during the horizontal retrace period.

The current flowing through the vertical concentration electrode (3) during the horizontal retrace period is converted into a voltage value by a current-voltage conversion circuit (■), which is then converted into a voltage value by two sample-and-hold circuits ( 51a ) (51b) to independently interpolate the currents emitted from the line cathodes (2a) and (2b).

Similarly, the voltages corresponding to the vibrations of the two wire cathodes (2a) and (2b) are converted into two series of phase conversion circuits (52a) (52b).
), and then applied to the line cathode drive output circuit.

Effects of the Invention The present invention prevents the vibration of the line cathode by detecting the vibration of the line cathode and electrically applying forced damping to the line cathode using a detection signal. 1 (1/5ec) was obtained. This value is 0.001 to 0.0 without applying electrical damping.
1 (1/5ec), this was an improvement of more than two orders of magnitude, and no deterioration in image quality due to the vibration of the line cathode was observed.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of an image display element used in an image display device to which the present invention is applied, Fig. 2 is an enlarged view of the fluorescent screen of the image display element, and Fig. 8 is an illustration of driving the image display element. A block diagram of a drive circuit and waveform diagrams of various parts, FIGS. 4, 5, and 6. FIG. 7 is a waveform diagram of each part for explaining the operation of the drive circuit, and FIG. 4@8 is a block diagram of main parts of an image display device according to an embodiment of the present invention, and FIG. 9 is a diagram. Figure 10 is a waveform diagram for explaining the operation of the device;
FIG. 1 is a block diagram of the main parts of an image display device according to another embodiment of the present invention, and FIG. 12 is a waveform diagram for explaining the operation of the device. (1)...Back electrode, (2), (2a) to (2o
)... Line cathode &(3)'... Vertical focusing electrode, (4)...
... Vertical deflection electrode, (5) ... Beam flow control electrode, (
7)...Horizontal deflection electrode, (9)...Screen.

Claims (1)

[Claims] 1. A wire cathode stretched in a vacuum, means for electrically detecting the position due to vibration of the wire cathode, and means for converting the detected position into a signal corresponding to the speed of vibration of the wire cathode. , the linear cathode is made of An image display device in which vibration of a line cathode is suppressed by equivalently increasing the damping constant of the vibration system.