JPH02116274A - Picture display device - Google Patents

Abstract

PURPOSE:To reduce the number of A/D converters and to make the title device compact by providing a third switch, which selects the respective outputs of first and second A/D converters, and controlling an electronic beam quantity by means of the outputs. CONSTITUTION:One signal is selected out of respective R, G and B video signals 51 to 53 by switches 54 to 56, and inputted to a first A/D converter 71. One signal is selected out of the signals by switches 57 to 59, and inputted to a second A/D converter 72. Further, for the respective outputs of the first and second A/D converters 71 and 72 signal-processed by the clock of a control circuit 73, the signal is switched by a switch 74 controlled by a control circuit 73, they are made into a set serial data, the output is stored into a one- horizontal scanning period memory 75, and at the time of a completion, it is pulse-width converted by a PWM circuit 76 to be the time control pulse of a pulse width, applied to an electronic beam control electrodes 5, and a video is reproduced. Thus, the two A/D converters of the R, G and B video signals can produce the performance, and the device can be made compact.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention generates an electron beam for each division when a screen on a screen is vertically divided into a plurality of divisions, and generates an electron beam for each division. The present invention relates to an apparatus for displaying a plurality of lines by vertically deflecting a beam to display a television image as a whole.

Conventional technology Traditionally, cathode ray tubes have been mainly used as display elements for displaying color television images, but conventional cathode ray tubes have a very long depth compared to the screen size, making it difficult to use thin television screens. It was impossible to create a receiver. Furthermore, although KL display elements, plasma display devices, liquid crystal display elements, and the like have recently been developed as flat display elements, all of them are insufficient in terms of performance such as brightness, contrast, and color display.

Therefore, Japanese Patent Application No. 56-20618 (Japanese Unexamined Patent Publication No. 57-1989) has proposed a method for achieving a flat display device using electron beams.
135590), a new display device was proposed.

This method generates an electron beam for each section when the screen is vertically divided into multiple sections, and displays multiple lines by deflecting each electron beam vertically for each section. However, it displays a television image as a whole.

First, a basic configuration example of the image display element used here will be briefly explained with reference to FIG. This display element is
In order from rear to front: back electrode 1, line cathode 2 as a beam source, vertical focusing electrode 3.3', vertical deflection electrode 4, electron beam control electrode 5, horizontal focusing electrode 6, horizontal deflection electrode 7, beam It consists of an accelerating electrode 8 and a screen 9, which are housed inside a flat glass bulb (not shown) that is evacuated.

A line cathode 2 serving as a beam source is stretched horizontally so as to generate an electron beam distributed linearly in the horizontal direction, and a plurality of line cathodes 2 (here, Only four (2a to 2d are shown) are provided. In this example, it is assumed that 15 are provided.

Let them be 2a to 2o. These wire cathodes 2 are constructed by coating the surface of a tungsten wire with a diameter of 10 to 20 μΦ with an oxide cathode material for thermionic emission. These line cathodes 2a to 2o are heated so as to generate a thermionic electron beam when a current is passed through them.
As will be described later, the electron beams are controlled to be emitted sequentially from the line cathode 2a for a fixed period of time. Back electrode 1
acts to suppress the generation of electron beams from line cathodes other than the line cathode that is controlled to emit electron beams for a certain period of time, and to push the generated electron beams only in the forward direction. . This back electrode 1 may be formed by a coating of electrically conductive material applied to the inner surface of the rear wall of the glass bulb. Further, instead of the back electrode 1 and the linear cathode 2, a planar electron beam emitting cathode may be used.

The vertical focusing electrode 3 is a conductive plate 11 having a horizontally long slit 10 facing each of the line cathodes 2a to 2o. Focus.

Electron beams for one horizontal line (360 pixels) are taken out at the same time. In the figure, only one section in the horizontal direction is shown. The slit 10 may be provided with crosspieces at appropriate intervals in the middle, or may be a row of through-holes arranged horizontally at small intervals (so that they almost touch each other). Alternatively, it may be configured as a slit. The vertical focusing electrode 3' is also similar.

A plurality of vertical deflection electrodes 4 are arranged horizontally in the middle of each of the slits 10, and are each composed of conductors 13 and 13' provided on the upper and lower surfaces of the insulating substrate 12. has been done.

Then, a vertical deflection voltage is applied between the opposing conductors 13 and 13' to deflect the electron beam in the vertical direction.

In this example, the pair of conductors 13, 13' deflects the electron beam from one line cathode 2 to positions corresponding to 16 lines in the vertical direction. The 16 vertical deflection electrodes 4 constitute 15 conductor pairs corresponding to each of the 15 line cathodes 2, and the electron beam is deflected to draw 240 horizontal lines on the screen 9. .

Next, the control electrodes 5 are composed of conductive plates 15 each having a vertically long slit 14, and a plurality of control electrodes 15 are arranged in parallel in the horizontal direction at predetermined intervals. In this example 1
Eighty control electrode conductive plates 15-1 to 15-n are provided (only nine are shown in the figure). Each of the control electrodes 5 extracts the electron beam horizontally by dividing it into two picture elements each, and controls the amount of electron beam passing therethrough in accordance with a video signal for displaying each picture element. Therefore, if 18,080 conductive plates 15-1 to 15-0 for control electrode 5 are provided, 360 pixels can be displayed per horizontal line. In addition, in order to display images in color, each picture element is R
,G.

Display is performed using phosphors of three colors, B, and R, G, and B video signals for two picture elements are sequentially applied to each control electrode 5. In addition, 180 conductive plates 15-1 to 15 for control electrodes 5
180 sets of video signals for one line (two picture elements per set) are simultaneously applied to each of -n, and the video for one line is displayed at one time.

The horizontal focusing electrode 6 is composed of a conductive plate 17 having a plurality of vertically long slits 16 (180 slits) facing the slits 14 of the control electrode 5, and collects electrons for each pixel divided in the horizontal direction. Each beam is focused horizontally into a narrow electron beam.

The horizontal deflection electrodes 7 include a plurality of conductive plates 18.1 arranged vertically on both sides of the slit 16.
8', six levels of horizontal deflection voltage are applied to each electrode 18, 18' to horizontally deflect the electron beam of each pixel, and two sets of electron beams are displayed on the screen 9. The 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 acceleration electrode 8 is composed of a plurality of conductive plates 19 provided horizontally at the same position as the vertical deflection electrode 4.
The electron beam is accelerated to collide with the screen 9 with sufficient energy.

The screen 9 is constructed by applying a phosphor 20 that emits light when irradiated with an electron beam to the back surface of a glass plate 21, and adding a metal back layer (not shown).

The phosphors 20 are provided with two pairs of phosphors of three colors R, G, and B for each slit 14 of the control electrode 5, that is, for each horizontally divided electron beam. It is applied in vertical stripes.

In FIG. 5, the broken lines drawn on the screen 9 indicate divisions in the vertical direction that are displayed corresponding to each of the plurality of line cathodes 2, and the two-dot chain lines correspond to each of the plurality of control electrodes 5. Indicates the horizontal division displayed. In one section separated by both of these.

As shown in an enlarged view in FIG. 6, there are R, G, and B phosphors 20 for two picture elements in the horizontal direction, and a width for 16 lines in the vertical direction. The size of one section is, for example, IIwl in the horizontal direction and 10III11 in the vertical direction.

Note that in FIG. 5, the length in the horizontal direction is greatly enlarged relative to the length in the vertical direction for clarity.

Further, in this example, only one pair of R, G, and B phosphors 20 for two picture elements are provided for one control electrode 5, that is, for one electron beam, but of course, one picture element Alternatively, three or more picture elements may be provided, and in that case, the control electrode 5 has R, G, and B for one picture element or three or more picture elements.
Video signals are applied sequentially, and horizontal deflection is performed in synchronization with the video signals.

The basic configuration of the flat panel image display device has been described above. Here, a conventional example of a sequential circuit for R2O and B video signals, which is the object of the present invention, will be described.

FIG. 3 shows an R, G, and B video signal processing device for the above-mentioned image display element. The color television signal passes through a color demodulation circuit and becomes R, G, and B signals, and FIG. 3 shows the subsequent signal processing apparatus. In FIG. 3, R, G, and B signals 51, 52, and 53 are connected to three A/D converters 61, 62.
．． 63, the analog signal is converted into a digital signal. When performing A/D conversion, the control circuit 64
Clock 65 for D converter 61, 62°63,
Shift the phase of 66 and 67 by 120' to increase resolution.

4(b), (c), and (d) show clocks 65, 66.
Each A/D converter 61 when the phase of 67 is shifted,
62.63 output data is shown. Furthermore, each of the above A
/D converters 61, 62, 63 outputs by switch 68
and converts the data of R, G, and B signals 51, 52, and 53 into one serial data. The output is shown in FIG. 4(e). The output data is stored in a memory 69 for one horizontal scanning period, and then pulse width modulated in a PWM (pulse width modulation) circuit 70 to drive the electron beam control electrode 5 shown in FIG. As described above, conventionally, three A/D converters 61, 62, and 63, which have high resolution and high conversion speed, have been used to process video signals.

Problems to be Solved by the Invention As described above, in the past, R, G, and B signal processing was performed using three A/D converters to convert each signal into integrated serial data. However, A/D converters are expensive, and it would be too costly to commercialize an image display device.
Furthermore, if there are a large number of A/D converters, there is a problem in that it is difficult to package the entire device into a single chip IC and implement it compactly.

The present invention solves the above problems, and aims to provide an image display device that can be made compact and inexpensive by reducing the number of A/D converters.

Means for Solving the Problems In order to solve the above problems, the image display device of the present invention includes:
a first switch group for selecting one of the R2O and B signals obtained by demodulating the television screen signal into three primary colors;

a circuit that converts the output with a first A/D converter;
a second switch group that selects one of the R, G, and B signals at a timing different from that of the first switch group; and a circuit that converts the output thereof with a second A/D converter; The third one selects each output of the first and second A/D converters.
A switch is provided, and the output is used to control the electron beam.

Effects With the above configuration, the need for an expensive A/D converter can be reduced, and A/D conversion of R, G, and B video signals of an image display device can be realized inexpensively and compactly.

EXAMPLE Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is a circuit diagram of a video signal processing circuit of an image display device in one embodiment of the present invention. In Figure 1, R, G
, B, the video signals 51, 52, 53 are first sent to the switch 54.
, 55, 56, one signal is selected and input to the first A/D converter 71. Also, switch 57°58.59
However, one signal is selected and input to the second A/D converter 72. Further, the outputs of the first and second A/D converters 71 and 72, which are signal-processed by the clock of the control circuit 73, are switched by a switch 74 controlled by the control circuit 73, and are converted into one serial data. becomes. The output is stored in the memory 75 for one horizontal scanning period, and when it is completed, it is pulse width modulated by the PwM circuit 76 and applied to the electron beam control electrode 5 as a pulse width time control pulse to reproduce the image.

The above signal processing will be explained using the timing diagram of FIG. Figure 2 (a), (b), and (c) are R and G, respectively.

The analog waveforms of the B video signals 51, 52, and 53 are temporally divided in an easy-to-understand manner. This signal is switched by a switch switching pulse generated by a control circuit 73 using switches 54 to 59. FIG. 2(d) shows the input signal of the A/D converter 71, which is the switching output of the switches 54, 55 and 56. That is, the signal shown in FIG. 2(d) input to the A/D converter 71 is first closed by the switch 54 to obtain the R1 signal, then the switch 56 is closed to obtain the 81 signal, and then the switch 55 is closed. The signals are switched in such a manner that a closed 02 signal is obtained. The same applies to the signal shown in FIG. 2(e) that is input to the A/D converter 72. Thereafter, sampling is performed by A/D converters 71 and 72, and the output thereof is then alternately switched by switch 74 to obtain an output from switch 73 as shown in FIG. 2(f). After that, the electron beam is controlled by performing the same processing as the conventional circuit.

Effects of the Invention As described above, according to the present invention, R, G,
Instead of the conventional three A/D converters for B video signals, it is now possible to achieve the same performance with two, allowing the device to be provided at a lower cost, and making the video signal processing section a single chip IC. This makes it possible to realize a flat-screen television by compactly mounting the device.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a video signal processing circuit of an image display device according to an embodiment of the present invention, FIG. 2 is a timing diagram thereof, FIG. 3 is a circuit diagram of a conventional video signal processing circuit, and FIG. 4 is a circuit diagram thereof. FIG. 5 is a perspective view showing the basic configuration of the image display device, and FIG. 6 is an enlarged view of the screen. DESCRIPTION OF SYMBOLS 1... Back electrode, 2,2a-2o... Line cathode, 3°3'... Vertical focusing electrode, 4... Vertical deflection electrode, 5...
...Electron beam control electrode, 6...Horizontal focusing electrode, 7.
...Horizontal deflection electrode, 8...Beam acceleration electrode, 9...
Screens, 51, 52, 53...R, G, B video signals, 54, 55, 56, 57, 58. 59...Switch, 71, 72...A/D converter, 73...Control circuit, 74...Switch, 75...
-Memory, 76...PWM circuit. Agent Yoshihiro Morimoto also joined the

Claims (1)

[Claims] 1. A plurality of line cathodes, a focusing electrode that focuses the electron beam from the line cathode, a deflection electrode that deflects the electron beam in vertical and horizontal directions, and a screen that emits light when irradiated with the electron beam; an R signal obtained by demodulating the signal into three primary colors, comprising an electron beam control electrode that controls the amount of the electron beam and the brightness on the screen according to a television signal or a similar signal;
a first switch group for selecting one of the G signal and the B signal;
a circuit that converts the output with a first A/D converter; a second switch group that selects one of the R signal, G signal, and B signal at a timing different from that of the first switch group; A circuit that converts the output with a second A/D converter and a third switch that selects each output of the first and second A/D converters are provided, and the output of the third switch is used to convert the electron beam into the electron beam. An image display device that controls the amount of