JPH01173552A - Linear cathode driving method for plane type image display device - Google Patents

Abstract

PURPOSE:To obtain a good image with small power consumption by intermittently heating a linear hot cathode. CONSTITUTION:A linear cathode 2 is intermittently heated. This intermittent heating can be performed, for example, when an electron beam is once emitted, the electron beam is extracted at some potential, then it is kept at the potential on the low potential side for a while without being immediately returned to the heating potential of the linear cathode 2, and it is again returned to the heating potential of the linear cathode 2. The power consumption is considerably reduced as compared with the heating time of the conventional linear cathode, and a good image can be obtained with less power consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an image display device for video equipment.

Conventional technology Traditionally, cathode ray tubes have been mainly used as display elements for displaying color television images. It was impossible to produce.

In addition, although EL display elements, plasma display devices, liquid crystal display elements, etc. have recently been developed or commercialized as flat display elements, all of them have drawbacks in terms of performance such as brightness, contrast, and color reproducibility. That's enough.

Therefore, in order to achieve a device that can display color television images on a flat display device using electron beams, the screen on the screen is vertically divided into multiple sections. Each time, the electron beam is deflected vertically to display multiple lines, and
Divide into multiple sections horizontally and set R, G, B for each section.
The R, G, B phosphors are made to emit light sequentially, and
It has been proposed to display a television image as a whole by controlling the amount of electron beam irradiation onto a phosphor such as a color video signal.

Examples of conventional image display elements will be described below with reference to the drawings. 3 and 4 show conventional image display elements. In FIG. 3, back electrodes 1. Back spacer electrode 23. Line hot cathode (hereinafter referred to as line cathode) as an electron beam source2. Vertical focusing electrode 3a.

3b, vertical deflection electrode 4. The electron beam flow control electrode 5, horizontal focusing electrodes 6a and 6b, horizontal deflection electrode 7, electron beam accelerating electrode 8, and glass containers 9, 22 are arranged, and the components are inside the glass container 9, 22. It is stored and evacuated.

The operation of the image display device configured as described above will be described below. First, a line cathode 2 as an electron beam source is stretched horizontally so as to generate an electron beam distributed linearly in the horizontal direction.
are vertically spaced at appropriate intervals (here, 2 to 2)
(Only 4 pieces of 22 are shown). In this embodiment, it is assumed that 15 pieces are provided, and 2I to 2Y are provided. These wire cathodes 2 are constructed by applying an oxide cathode material to the surface of a tungsten wire having a diameter of 10 to 20 μm, for example. Then, as described later, the upper line cathode 2
The electron beams are controlled to emit electron beams for a certain period of time in order from A to A. The back electrode 1 and the back spacer electrode 23 are a line cathode 2 that is controlled to emit an electron beam for a certain period of time, which will be described later.
suppressing the generation of electron beams from other line cathodes 2,
It also functions to push out the generated electron beam only in the forward direction. In place of the back electrode 1 and the linear cathode 2, a planar electron beam emitting cathode may be used.

The vertical focusing electrode 3a is a conductive plate 11 having a horizontally long slit 10 facing each of the line cathodes 2a to 2yo, and extracts the electron beam emitted from the line cathode 2 through the slit 10, and focus in a direction. The slits 10 may be provided with holes at appropriate intervals in the middle, or may be a row of through holes provided horizontally at small intervals (so that they almost touch each other). Alternatively, it may be configured as a slit. This is similar to the vertical focusing electrode 3b. The vertical deflection electrode 4 is
A plurality of slits 10 are horizontally arranged in the middle of each slit 10, and dielectrics 13a and 13b are provided on the upper and lower surfaces of an insulating substrate 12, respectively. Then, the conductors 13a, 1 facing each other
3b, a vertical deflection voltage is applied to deflect the electron beam in the vertical direction. In this configuration example, a pair of conductors 13
The electron beam from one line cathode 2 is vertically deflected to a position corresponding to 16 lines by a and 13b. And 1
The six vertical deflection electrodes 4 constitute 15 conductor pairs corresponding to each of the 15 line cathodes 2, and ultimately deflect the electron beam to form 240 horizontal lines on the screen 21.

Next, the electron beam flow control electrodes 5 are composed of conductive plates 15 each having a vertically long slit 14, and a plurality of electron beam flow control electrodes 5 are arranged horizontally in parallel at predetermined intervals.

In this configuration example, 320 control electrode conductive plates 15a to 1
5n are provided (only 10 are shown in the figure)
. Each of the electron beam flow control electrodes 5 separates and extracts the electron beam into one picture element 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 electron beam flow control electrode 5
If 32,020 pixels are provided, 320 picture elements can be displayed per horizontal line. In addition, in order to display images in color, each picture element is displayed with phosphors of three colors, R, G, and B, and each electron beam flow control electrode 5 is provided with each image of R, G, and B. Signals are applied sequentially. Furthermore, 320 sets of video signals for one line are simultaneously applied to the 320 electron beam flow control electrodes 5, so that one line of video is displayed at one time. A plurality of horizontal focusing electrodes 6a (320) are long in the vertical direction and face the slit 14 of the electron beam flow control electrode 5.
It is composed of a conductive plate 17 having slits 16, and focuses the electron beams of each picture element divided horizontally into a fine electron beam.

The horizontal deflection electrode 7 is made up of a plurality of conductive plates 18 arranged vertically in the middle of each of the slits 16, and a horizontal deflection voltage is applied between each conductive plate 18 for each pixel. The electron beams are respectively deflected in the horizontal direction, and the R, G, and B phosphors are sequentially irradiated on the screen 21 to cause them to emit light. In this embodiment, the deflection range is the width of one picture element for each electron beam. The electron beam accelerating electrode 8 is composed of a plurality of conductive wires 19 provided horizontally at the same position as the vertical deflection electrode 4, and accelerates the electron beam so that it collides with the screen 21 with sufficient energy. .

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

The phosphor 20 is R and G for one slit 14 of the electron beam flow control electrode 5.

One pair of three color B phosphors are provided, and they are applied in stripes in the vertical direction.

In FIG. 3, the broken lines drawn on the screen 21 indicate divisions in the vertical direction corresponding to the plurality of line cathodes 2, and the two-dot chain lines indicate the plurality of electron beam flow control electrodes 5.
Shows the horizontal divisions displayed corresponding to each. As shown in the enlarged view in Figure 4, one section divided by these two has R, G, and B for one pixel in the horizontal direction.
phosphor 20, and has a width of 16 lines in the vertical direction.

Note that in the figure, A is one section in the vertical direction, and B is one section in the horizontal direction. The size of one section is, for example, 111 mm in the horizontal direction and 10 mm in the vertical direction. Note that in FIG. 4, the length in the horizontal direction is greatly enlarged relative to the length in the vertical direction for clarity. Further, in this embodiment, only one pair of R, G, and B phosphors 20 for one picture element is provided for one electron beam flow control electrode 5, that is, for one electron beam. Of course, two or more picture elements may be provided, and in that case, the electron beam flow control electrode 5 sequentially separates R, G, and B video signals for two or more picture elements, and synchronizes with them. A horizontal deflection is made.

The above is the general principle of the image display device.

Next, the driving method of the above device, particularly the line cathode 2, will be explained. As shown in FIG. 5, the driving of the linear cathode 2 is divided into a potential V2 for heating the linear cathode 2 and exciting electrons, and an electron beam jumping potential V by applying a pulse voltage. The time width t of the pulse corresponds to one section divided in the vertical direction (in the embodiment, one section out of 15 sections, 16 lines in terms of the number of lines). As shown in FIG. 5, this pulse v1 forms one frame of screen by sequentially taking out scan L electron beams from the line cathodes 2A to 2Y. The actual heating of the linear cathode 2 is as shown in FIG.
This is done by applying a potential V3, which is lower than the potential of V2, to the opposite side through a diode, thereby causing a current to flow through the line cathode 2. As shown in FIG. 5, since the line cathode heating potential v2 is applied to the entire time other than the electron beam ejection time t1, this heating is performed during the entire time other than the electron beam ejection time t1.

Problems to be Solved by the Invention However, in the linear cathode driving device as described above, the heating time of the linear cathode (12 in FIG. 5) is long, and the power consumption is large. In particular, as the number of vertical blocks, ie, the number of line cathodes, increases, the power consumption increases, which becomes a serious problem in practice. In the above example, if the frame frequency ratio is 60 and the number of line cathodes is 15, then the line cathode heating time (t2 in Figure 5
) is approximately 14m5ec. The current per wire cathode is 11. The potential difference between the left and right sides of the wire cathode is ΔV (v2-V3 in Figure 5.
), the total power consumption of the line cathode per second is 60X15XiXΔVx0.014=12.6iXΔ
It becomes V.

Means for Solving the Problems In order to solve the above problems, in the present invention, the wire cathode is heated intermittently. In this intermittent heating, for example, after emitting an electron beam and taking it out at a certain potential, the electron beam is not returned to the line cathode heating potential immediately, but after being kept at a lower potential for a while, the electron beam is returned to the line cathode heating potential. This can be done by reverting.

Effect: According to the present invention, with such a configuration, the power consumption can be considerably reduced compared to the conventional line cathode heating time.

An example illustrates a reasonable range of off-time for this line cathode heating. As shown in Figure 8, when the wire cathode is heated and the heating temperature of the wire cathode is maintained at approximately 950''K, and the heating of the wire cathode is stopped, the temperature decreases approximately in proportion to the time. Then, of course, the line cathode temperature drops to a low temperature, and it takes time to return it to the required excitation temperature of 950° K, making it impossible to extract the electron beam at t5 at the time of the next electron beam extraction pulse.However, the above-mentioned conventional example If the line cathode heating is turned off with a line cathode heating time of about 14 m5ec (t2 in Figure 5), the line cathode temperature will drop to at most about 30'' from Figure 8, and reheating will immediately raise the required excitation temperature to 950. "K" can be returned.Actually, t in Figure 7
When heating is turned off for all of the line cathode heating times corresponding to 4, the heating time t4 becomes 0, and while the temperature of the line cathode decreases, the electron beam cannot be extracted. Therefore, it is appropriate that the time t3 during which the line cathode temperature decreases when the line cathode heating is turned off is approximately 1:1 with the time t4 during which the line cathode temperature rises when the line cathode heating is turned on. Of course, with detailed analysis, it is quite possible to further lengthen the line cathode heating off time as much as possible.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A line cathode drive device for a flat panel image display device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a waveform diagram of a line cathode driving device according to an embodiment of the present invention, and the image display device of the present invention has a frame frequency of 60 Hz and a line cathode number of 15. t is the electron beam ejection time, t3 is the line cathode heating off time, and t4 is the line cathode heating time.

In this embodiment, the line cathode heating time t4 and the line cathode heating off t3
Since the ratio is approximately 1:1, the line cathode heating time t4 is approximately 7 m5.
ec, and as a result of the experiment, it was possible to obtain a good image, which was the same as the line cathode heating time of 14 m5 ec in the conventional example.

In FIG. 2, ``A'' shows the conventional line cathode driving method, and ``A'' shows the line cathode driving method of this embodiment. As shown in FIG.
, frame frequency 60Hz.

Assuming that the number of cathodes is 15, the power consumption P1 required for one second in the conventional example shown in Fig. 2 A is 60x15xixΔ
Vx0.014=12.6ixΔv1 The power consumption P2 required for one second in this example shown at the beginning of Figure 2 is 60X
15x i

Results of the Invention As described above, according to the drive device using intermittent heating of a line cathode of the present invention, good image reproduction of a flat panel image display device can be realized with low power consumption.

[Brief explanation of the drawing]

FIG. 1 is a time chart of a line cathode driving device of an image display device according to an embodiment of the present invention, and FIG. 2 is a time chart showing a comparison between a conventional example and a line cathode drive method according to an embodiment of the present invention. 3 is an exploded perspective view showing the basic configuration of the image display device, FIG. 4 is an enlarged plan view showing the phosphor surface of the image display device, FIG. 5 is a waveform diagram of a conventional line cathode drive device, and FIG. A circuit diagram showing the linear cathode driving device, FIG. 7 is a waveform diagram of the linear cathode driving device according to the embodiment of the present invention, and FIG. 8 shows the relationship between the time after the heating of the linear cathode is turned off and the temperature of the linear cathode. FIG. 2... Line cathode, 24... Line cathode drive circuit, 25... Frame period (60 in this example).
Hz). Name of agent: Patent attorney Toshio Nakao and 1 other person z-n #
臘24--Ichiso #Koji! Fl Eyeball Figure 1 Time - Figure 2 Poetry - i Katama - Figure 4 Figure 5 Figure 6? Figure 7 Timetable-

Claims (1)

[Claims] A plurality of linear hot cathodes, an electrode means for extracting an electron beam from the linear hot cathode, a plurality of electrode means for controlling, deflecting or accelerating the electron beam, and light emission due to collision of the electron beam. A flat image display device comprising a display means coated with a phosphor in a transparent glass container, the linear hot cathode being heated intermittently. Cathode drive device.