JPH0594784A - Image display apparatus - Google Patents

Abstract

PURPOSE:To provide an image display apparatus which suppresses electromagnetic wave jamming against appliances such as a radio, a television, etc., dealing electric wave and provides fine images by itself. CONSTITUTION:A back side metal plate 103 of an image display element is connected with metal plates 101A, 101B for shielding a printed circuit board 102 of a driving circuit, so that electromagnetic wave jamming due to not only the dribing circuit but a beam flow controlling electrode inside the image display element is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generates an electron beam for each division when a screen on a screen is divided into a plurality of divisions in the vertical direction, and emits each electron beam in the vertical direction for each division. The present invention relates to an image display device that deflects and displays a plurality of lines to display an image as a whole.

[0002]

2. Description of the Related Art The basic structure of an image display element used in a conventional image display device will be described with reference to FIG.

This display device has a back electrode 1, a line cathode 2 as a beam source, a beam extraction electrode 3, a beam flow control electrode 4, a focusing electrode 5 in this order from the rear to the anode side.
A horizontal deflection electrode 6, a vertical deflection electrode 7, a screen plate 8, etc. are arranged and configured, and these are housed inside a vacuum container.

A line cathode 2 as a beam source is stretched in the horizontal direction so as to generate an electron beam which is linearly distributed in the horizontal direction. Only 7 of 2 a to 2 are shown.) Provided. In this configuration, the line cathode spacing is 4.4.
Assuming that there are 19 mm, the number of the line cathodes is 2 to 2 mm. The distance between the line cathodes cannot be set freely, and is regulated by the distance between the vertical deflection electrode 7 and the screen 8 which will be described later. As a configuration of these wire cathodes 2, an oxide cathode material is applied to the surface of a tungsten rod having a diameter of 10 to 30 μm. As will be described later, the above-mentioned line cathode is controlled so as to sequentially emit an electron beam from the upper line cathode 2a to the lower two line cathodes at regular intervals. The back electrode 1 suppresses the generation of an electron beam from a line cathode other than the corresponding line cathode, and also has the function of pushing out the electron beam only toward the anode. Although a vacuum container is not shown in FIG. 3, it is possible to use the back electrode 1 to form a structure integrated with the vacuum container. The beam extraction electrode 3 is provided with a plurality of through holes 10 which are arranged in a row in the horizontal direction facing each of the line cathodes 2a to 2a at regular intervals.
The electron beam emitted from the linear cathode 2 is taken out through the through hole 10. Next, the control electrode 4 is composed of a vertically long conductive plate 15 having a through hole 14 at a position facing each of the line cathodes 2a to 2c, and a plurality of control electrodes 4 are arranged side by side in a horizontal direction at a predetermined interval. Has been done. In this configuration, 114 control electrode conductive plates 15a are provided.
~ 15n are provided. (In FIG. 3, only eight are shown). The control electrode 4 controls the passing amount of each of the electron beams divided in the horizontal direction by the beam extraction electrode 3 in correspondence with the picture element of the video signal and in synchronization with the horizontal deflection timing described later. . Focusing electrode 5
Is a conductive plate 17 having a through hole 16 at a position facing each through hole 14 provided in the control electrode 4, and focuses the electron beam. The horizontal deflection electrode 6 is composed of a plurality of conductive plates 18 and 18 'vertically arranged along both sides of the through hole 16 in the horizontal direction, and each of the conductive plates has a horizontal deflection voltage. Is being applied. The electron beam for each picture element is deflected in the horizontal direction, and the R, G, and B phosphors are sequentially irradiated on the screen 8 to emit light. In this configuration, each electron beam is deflected by 2 trio. The vertical deflection electrode 7 is composed of a plurality of conductive plates 19 and 19 'arranged in the horizontal direction at intermediate positions in the vertical direction of the through hole 16, and is applied with a vertical deflection voltage to generate an electron beam. Vertically biased.
In this configuration, the electron beam generated from one line cathode is deflected by 12 lines in the vertical direction by the pair of electrodes 19 and 19 '. And a vertical deflection electrode 7 composed of 20 pieces
Defines 19 pairs of vertical deflection conductors corresponding to each of the 19 line cathodes, and draws 228 horizontal scan lines in the vertical direction on the screen 8. As described above, in this configuration, a plurality of horizontal deflection electrodes 6 and vertical deflection electrodes 7 are arranged in a comb shape. Further, by setting the distance to the screen 8 longer than the distance between the horizontal and vertical deflection electrodes, it becomes possible to irradiate the screen 8 with an electron beam with a small deflection amount. As a result, horizontal and vertical co-deflection distortion can be reduced. The screen 8 is, as shown in (FIG. 3),
The fluorescent material 20 is applied in stripes on the back surface of the glass plate 21. Although not shown, metal back and carbon are also applied. The phosphor 20 is provided so as to horizontally deflect the electron beam passing through one through hole 14 of the control electrode 4 so as to irradiate the phosphor pairs of three colors of R, G, and B for two trios. And is applied in stripes in the vertical direction. In FIG. 3, the broken lines drawn on the screen 8 indicate vertical divisions corresponding to the plurality of line cathodes 2, and the two-dot chain line corresponds to each of the plurality of control electrodes 4. Shows the horizontal divisions displayed. An enlarged view of one section partitioned by a broken line and a two-dot chain line is shown in (FIG. 4).

As shown in FIG. 4, the phosphors of R, G and B for 2 trios in the horizontal direction and the width for 12 lines in the vertical direction are provided. In this example, the size of one section is 1 mm in the horizontal direction and 4.4 mm in the vertical direction. In addition (in FIG. 4), R,
Although the phosphors of three colors G and B are illustrated in a stripe shape, they may be arranged in a delta shape. However, when they are arranged in a delta shape, it is necessary to apply horizontal deflection and vertical deflection waveforms suitable for them. Further, in FIG. 4, the vertical and horizontal dimensional ratios are different from the image actually displayed on the screen for convenience of explanation. Further, in the present configuration, two trio of R, G, and B phosphors are provided for one through hole 14 of the control electrode 4, but one trio or three or more trio may be provided. good. However, 1 trio for the control electrode 4,
Alternatively, it is necessary to sequentially apply R, G, and B video signals of 3 trios or more and perform horizontal deflection in synchronization with them.

Next, the operation of the drive circuit for driving this display element will be described with reference to FIG. First, the drive portion that irradiates the screen 8 with the electron beam and displays the electron beam will be described. The power supply circuit 22 is a circuit for applying a predetermined bias voltage to each electrode of the display element.
1, V3 for the beam extraction electrode 3 and V3 for the focusing electrode 5
5. A DC voltage of V8 is applied to the screen 8.

The pulse generating circuit 39 uses the vertical synchronizing signal V and the horizontal synchronizing signal H to create a line cathode drive pulse.
The timing chart is shown in FIG. Each line cathode 2 a-2
As shown in ((FIG. 5 (a-ma)), the current is flowing while the drive pulse is at a high potential and is heated, and electrons are emitted during a period when the drive pulse (a-ma) is at a low potential. The heating state is maintained as described above.

As a result, electrons are emitted from the 19 line cathodes 2a to 2t only during the 12 horizontal scanning periods in which low potential drive pulses (a tot) are applied. In order to form one screen, the potentials may be sequentially switched from the upper line cathode 2a to the lower line cathodes 2 by 12 scanning periods.

Next, the deflection portion will be described. The deflection voltage generation circuit 40 includes a direct memory access controller (hereinafter referred to as a DMA controller) 41, a deflection voltage waveform storage memory (hereinafter referred to as a deflection memory) 42, a horizontal deflection signal generator 43h, a vertical deflection signal generator 43v, and the like. It is configured to generate vertical deflection signals v, v'and horizontal deflection signals h, h '. In this configuration, the vertical deflection signal is displayed in 228 horizontal scanning periods in one field in consideration of overscan. In addition, the memory address area storing the vertical deflection position information corresponding to each line is divided into a first field and a second field, and each has a set of memory capacity. When displaying, the data is read from the corresponding deflection memory 42, converted into an analog signal by the vertical deflection signal generator 43v, and added to the vertical deflection electrode 7. The vertical deflection position information stored in the deflection memory 42 is composed of substantially regular data every 12 horizontal scanning periods, and the waveform converted into the deflection signal is also a vertical deflection signal of approximately 12 stages. However, as described above, the memory capacity for two fields is provided so that the position can be finely adjusted for each horizontal scanning line. Further, with respect to the horizontal deflection signal, it is necessary to horizontally deflect the electron beam in six steps in one horizontal scanning period and a memory is provided so that the deflection position can be finely adjusted for each horizontal scanning. Therefore 1
Assuming that 456 horizontal scanning periods are displayed between frames, 45
6 × 6 = 2736 bytes of memory required, but first
Since the data of the field and the second field are shared, the memory of 1368 bytes is actually used. At the time of display, the deflection information corresponding to each horizontal scanning line is read from the deflection memory 42, converted into an analog signal by the horizontal deflection signal generator 43h, and added to the horizontal deflection electrode 6.

In summary, during the display period excluding the vertical blanking period of the vertical cycle, the electron beam emitted from the linear cathode of the linear cathodes 2a to 2c to which the low-potential drive pulse is applied. Are divided into 114 sections in the horizontal direction by the beam extraction electrode 3 to form 114 electrode beam rows. As will be described later, the control electrode 4 controls the beam passage amount of each electron beam, the electron beam is converged by the converging electrode 5, and then the electron beam changes in approximately six stages as shown in FIG. R1, G1, B1 and R2 of the screen 8 are displayed in each horizontal display period by the horizontal deflection electrodes 18, 18 'to which the horizontal deflection signals h, h' are added.
The phosphors such as G2 and B2 are sequentially irradiated with each horizontal display period / 6. Thus, the raster for each horizontal line is 114
R1, G1, B1 and R electron beams for each section
A color image can be displayed on the screen 8 by modulating with a video signal corresponding to 2, G2, B2.

Next, the electron beam modulation control portion will be described. First (FIG. 5), the signal input terminals 23R,
Each of the R, G, and B video signals added to 23G and 23B includes 114 sample and hold circuit groups, 31a to 31.
added to n. Each sample hold circuit group 31a-3
1n are for R1, G1, B1, and R2, respectively.
6 sample and hold circuits for G2, G2, and B2. The sampling pulse generation circuit 34 has a horizontal display period (about 5 times) of the horizontal period (63.5 μsec).
0 μsec), 684 (114 × 6) samplings corresponding to the R1, G1, B1 and R2, G2, B2 sample and hold circuits of the 114 sets of sample and hold circuits 31a to 31n, respectively. Pulse Ra
1 to Rn2 are sequentially generated. The 684 sampling pulses are added to the 114 sample-hold circuit groups 31a to 31n, 6 pulses each, so that each sample-hold circuit group has two picture elements when one line is divided into 114 pieces. Minutes R1, G1, B1, R
The video signals of 2, G2 and B2 are individually sampled and held. 114 sets of R sample-held
The video signals of 1, G1, B1, R2, G2 and B2 are 114 sets of memory 32 after the sample and hold for one line is completed.
Transfer pulses a to 32n are transmitted all at once by the transfer pulse t, and are held here for the next one horizontal scanning period. This retained R
The signals of 1, G1, B1, R2, G2 and B2 are applied to 114 switching circuits 35a to 35n. The switching circuits 35a to 35n are respectively R1, G1, and
It is composed of a circuit having individual input terminals of B1, R2, G2, B2 and a common output terminal for sequentially switching and outputting them, and switching pulses r1, g1, b1, r applied from the switching pulse generating circuit 36.
Switching control is performed simultaneously by 2, g2 and b2. The switch pulses r1, g1, b1, r2, g2, b2
Divides each horizontal display period into 6 and switches the switching circuits 35a to 35n for each horizontal display period / 6.
The video signals of 1, B1, R2, G2 and B2 are time-divisionally sequentially output and supplied to the pulse width modulation circuits 37a to 37n. The outputs of the switching circuits 35a to 35n are
114 sets of pulse width modulation (hereinafter referred to as PWM) circuits 37
a to 37n, R1, G1, B1, R2, G
The pulse width is modulated according to the magnitude of each of the video signals 2 and B2, and the video signals are output. The outputs of the pulse width modulation circuits 37a to 37n are individually applied as control signals for modulating the electron beam to the 114 conductive plates 15a to 15n of the control electrode 4 of the display element.

Next, the timing of horizontal deflection and display will be described. R in the switching circuits 35a to 35n
Switching of the video signals of 1, G1, B1, R2, G2 and B2, and the electron beam R by the horizontal deflection signal generator 43h
The synchronous control is performed so that the switching timing and the order of the horizontal deflection of the phosphors 1, G1, B1, R2, G2, B2 to the phosphors completely match. As a result, when the R1 phosphor is irradiated with the electron beam, the irradiation amount of the electron beam is controlled by the R1 control signal.
2, 2, G2, B2 are controlled in the same manner, and the emission of each phosphor of R1, G1, B1, R2, G2, B2 of each picture element is changed to that of R1, G1, B1, R2, G2, B2 of that picture element. Each picture element is controlled by the video signal, and each picture element is luminescently displayed according to the input video signal.
This control is simultaneously executed for 114 sets (two picture elements each) for one line, an image of 228 picture elements for one line is displayed, and 228 lines for one field are sequentially performed from the upper line, The image is displayed on the screen 8. Further, the above-described operations are repeated for each field of the input video signal, and the television signal or the like is displayed on the screen 8.

The basic clock required for this configuration is supplied from the pulse generating circuit 39 shown in FIG. 5 and the timing is controlled by the horizontal synchronizing signal H and the vertical synchronizing signal V.

[0014]

However, in the above-mentioned structure, the drive circuit for displaying an image on the element is all formed on the basis of the basic clock, and in particular, the pulse width modulation signal is used for the electron beam modulation control. Since it is used, there is a problem that interference with high frequency of the basic clock is given to other televisions and radios.

Therefore, the circuit printed board is shielded by two metal plates so that an interfering wave does not fly from the wiring pattern on the circuit printed board of the drive circuit. However, the shield of the circuit printed board is not sufficient, and the disturbing waves from the beam flow control electrode and the back electrode plate inside the image display device are not negligible.

In view of the above problems, the present invention provides an image display device which enhances the shield effect by a simple method, does not interfere with other televisions and radios, and displays a beautiful image by itself.

[0017]

In order to solve the above problems, an image display device of the present invention is characterized in that a metal plate for shielding a drive circuit and four corners of a back metal plate of an image display element are connected.

[0018]

According to the present invention, with the above-described structure, the potential of the back metal plate is stabilized, the back metal plate is prevented from becoming an antenna of an interfering wave, and the interfering wave from the beam flow control electrode is shielded. It suppresses the interfering waves from the beam flow control electrode and the back metal plate inside the TV, does not interfere with other televisions and radios, and can display a beautiful image by itself.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image display device according to an embodiment of the present invention will be described below with reference to the drawings. (Fig. 1 to 2)
FIG. 1A is a sectional view and an exploded perspective view of an image display element and a drive circuit of an image display device according to an embodiment of the present invention.

In the figure, 101A and 101B are metal plates for shielding which sandwich a circuit printed board 102 which constitutes a drive circuit therebetween. Reference numeral 103 is a back metal plate of the image display element, 105 is an electrode drive terminal for driving the beam flow control electrode 4 inside the image display element, and the beam flow control electrode 4 and the printed circuit board 1 of the drive circuit.
02 is electrically connected. Reference numeral 104 is a connection terminal for connecting the back metal plate 103 and the shield metal plate 101B.

In the image display device and the drive circuit configured as described above, the connection terminal 104 is welded or soldered to the rear metal plate 103, and the connection terminal 104 is provided.
Is soldered to the shield metal plate 101B to stabilize the potential of the rear metal plate 103,
03 to prevent it from becoming an interference wave antenna, and also to shield the interference wave from the beam flow control electrode 4, so that the beam flow control electrode 4 and the rear metal plate 10 inside the image display device are shielded.
The interference wave from 3 can be suppressed.

In the above description, the shield metal plate is 2
Although a large number of connecting terminals are arranged around the back metal plate (for example, every 2 cm), the shielding metal 101 is used.
B can be eliminated.

[0023]

As described above, according to the present invention, the potential of the back metal plate is stabilized, the back metal plate is prevented from becoming an antenna of the interference wave, and the interference wave from the beam flow control electrode is shielded. By suppressing the interfering waves from the beam flow control electrode and the rear metal plate inside the image display element, other televisions and radios are not disturbed, and a beautiful image can be displayed by itself.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an image display element and a drive circuit of an image display device according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a line cathode drive circuit and a line cathode protection circuit of the image display device.

FIG. 3 is an exploded perspective view of an image display device used in the present invention.

FIG. 4 is an enlarged view of a phosphor screen of the image display device.

FIG. 5 is a block diagram of a drive circuit of the image display device.

FIG. 6 is a waveform diagram for explaining the operation of the image display device.

[Explanation of symbols]

 101A, 101B Shield Metal Plate 102 Circuit Printed Circuit Board 103 Drive Circuit 103 Back Metal Plate 104 Connection Metal 105 Electrode Drive Terminal

Claims (2)

[Claims] 1. A vacuum envelope having a face plate and a back metal plate, a plurality of line cathodes arranged in the vacuum envelope to generate an electron beam, and an electron beam emitted from the line cathode. An image display element having a control electrode for controlling and a fluorescent film formed on the inner surface of the face plate to emit light by the entry of an electron beam, a circuit for driving the line cathode and the control electrode are arranged to display the image. A circuit printed board for displaying an image, the circuit printed board is sandwiched by two metal plates, the four corners of the back electrode are connected to the four corners of the metal plate, and shielding is performed. . 2. A vacuum envelope having a face plate and a back metal plate, a plurality of line cathodes arranged in the vacuum envelope to generate electron beams, and an electron beam emitted from the line cathodes. An image display element provided with a control electrode for controlling, a fluorescent film formed on the inner surface of the face plate and emitting light by the entry of an electron beam, an image display element provided with a circuit for driving the line cathode and the control electrode. An image display device, comprising: a circuit printed board for displaying an image on a screen, wherein the circuit printed board is sandwiched and shielded by the back metal plate and another metal plate.