JPH0422059A - Display tube for light source - Google Patents

Abstract

PURPOSE:To reduce dispersion of luminance at each picture element by connecting all of linear cathodes in series to each other, which are arranged in a matrix. CONSTITUTION:Cathodes 2 are connected in series to each other between cathode electrodes F1, F2; i.e., the number and arrangement of the cathodes is the same as usual and there is also dipersion in the contact resistance between each cathode 2 and a support electrode 50 supporting each cathode 2 as usual. However, all of the cathodes are connected in series to each other so the current flowing through each cathode is the same. The resistance value of each cathode depends on the length of each cathode and there is little variation in the length. Therefore cathode temperature is almost constant too and less electrons are emitted, and in addition, variation of luminance is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a light source display tube for configuring a large screen display device used in stadiums and the like.

C. Prior Art] FIG. 1 is a perspective view of each member of a fluorescent display device shown separately. In the figure, 1a is a display portion coated with phosphor, 1b is
1 is a spacer, and 10 is a substrate on which various control electrodes are arranged, and these constitute the vacuum container 1 of the display tube. 2
3 is a linear cathode, 3 is a first control electrode serving as a scanning electrode,
4 is a second control 1lit pole which becomes a data electrode. 5
and 6 is a wiring pattern commonly connecting both control l electrodes 3.4 in the row or column direction, 7 is a shielding electrode provided with a gate part 8 corresponding to the light emitting part, 9 is a fluorescent material, and 10 is the exhaust part.

Are there two types of systems in Figure 3? 2B shows the arrangement and wiring of the electrode. 31 to S4 are lead-out portions of the first control electrodes 3 commonly connected in the row direction, and D1 to D4 are lead-out portions of the second control electrodes 4 commonly connected in the column direction. FIG. 4 shows the timing of signals applied to each electrode, FIG. 5 shows the correspondence between the pixel arrangement and the electrodes, and FIG. 6 explains the potential of each electrode and the flow of electrons. FIG. 7 shows an equivalent circuit around a display tube and the potential relationship of each electrode in the prior art, and FIG. 8 shows wiring of cathodes arranged in a matrix inside the display tube.

Next, the operation will be explained. The basic principle of this type of display device is to accelerate thermionic electrons emitted from the cathode and cause them to collide with the anode, thereby exciting the phosphor coated on the anode surface and causing it to emit light.

In the 6th Fg, the thermoelectrons emitted from the cathode are generated as follows due to the combination of potentials of the first control electrode 3 (hereinafter referred to as scanning electrode) and the second control electrode 4 (hereinafter referred to as data electrode). . Each is shown in correspondence with FIG.

■ When the scanning electrode connected in the row direction and the data electrode connected in the column direction are both positive with respect to the cathode, electrons emitted from the cathode due to the positive potential of the data electrode are deflected by the potential of the scanning electrode. , passes through a predetermined opening, reaches the anode, and causes the phosphor to emit light.

(2) When the scan electrode is positive and the data electrode is negative, the negative potential of the data electrode near the cathode makes the potential near the cathode negative, suppressing the emission of thermoelectrons. Therefore, the phosphor does not emit light.

■ When the scan electrode is negative and the data electrode is positive, there are two cases as follows.

a. When the other scanning electrode is positive, the thermoelectrons emitted from the cathode are deflected toward the other scanning electrode by the potential of the scanning electrode, and the phosphor does not emit light.

b. When the other scanning electrode is also negative, the potential of the data electrode is positive, but because the area of the data electrode is small, the area near the cathode becomes negative due to the influence of the negative potential of the scanning electrodes on both sides, leading to the emission of thermoelectrons. is suppressed and the phosphor does not emit light.

(2) When both the scan electrode and the data electrode are negative, the potential near the cathode becomes negative, the emission of thermoelectrons is suppressed, and the phosphor does not emit light.

As a result, from the wiring relationship in Figure 3 and the relationship with the pixel arrangement in Figure 5, the phosphors located at the intersections of the row (scan > bipolar) and column (data) electrodes to which a positive potential is applied will emit light. First, when a signal is applied to Sl, the pH
~P]4 are selected, and these are the data voltages ff1(DI~
When a signal is applied to the 0th order 82 which emits light according to the potential of D4), F21-F24 are selected and also emits light according to the potential of the data electrode. In this manner, as shown in FIG. 4, by sequentially applying scanning signals to the scanning electrodes and applying arbitrary data signals to the data electrodes, it becomes possible to obtain an arbitrary display.

Figure 7 shows the potential relationship applied to each electrode.Since the cathode is a directly heated type, the potential gradient of the cathode is canceled out.
An alternating current is applied so as not to affect the brightness. Here, the positive or negative potential applied to the scan electrode and the data electrode is the potential with respect to the midpoint N of the cathode potential,
The same potential is supplied from a common power source.

On the other hand, the linear cathodes arranged in a matrix are
As shown in the figure, series connection in the row (or column) direction, column (
or rows) are connected in parallel. This is due to the structural advantage that wiring of each cathode becomes easy. Here, 50 is a support electrode that supports the cathode 2, and Fl and F2 are electrodes for flowing ti to the cathode.

[Problem to be solved by the invention]

A conventional display tube is configured as described above, where:
Since each of the cathodes arranged in a matrix is short, the resistance of each cathode is small, and the contact resistance with the support electrode that supports the cathode cannot be ignored. Furthermore, since the contact resistance itself has some variation, the current value that flows in the portion where the cathodes are connected in parallel will vary due to the variation in resistance value. This becomes especially noticeable as the number of cathodes connected in parallel increases. This results in variations in the temperature of the cathode, which leads to variations in the emission of thermoelectrons from the cathode, which in turn leads to variations in the brightness of each pixel in the display tube, which adversely affects display quality.

This invention was made to solve the above-mentioned problems, and aims to eliminate variations in temperature of linear cathodes arranged in a matrix, and to obtain high-quality display without variations in brightness. .

[! ! ! ! Means to solve B]

The light source display tube according to the present invention includes an anode formed by arranging phosphors in a matrix in a vacuum container, and a direct heating type having an anode in which phosphors are arranged in a matrix in a position facing the anode in correspondence with the phosphors. A light source display tube having a group of linear cathodes and a group of control electrodes for controlling the flow of electrons emitted from the cathodes is characterized in that the directly heated linear cathodes are connected in series.

[For production]

In this invention, by connecting all the linear cathodes arranged in a matrix in series, the current value flowing through each cathode can be made constant. This makes it possible to keep the temperature of each cathode constant and eliminate variations in display.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a cathode connection diagram for explaining the present invention in detail. In the embodiment, an example of 4 x 4 pixels is shown, but 8 x 8 pixels are shown in the figure.
Alternatively, as the density increases, as in the case of 16×161N elements, the electrode structure becomes more complicated. Here, this can be easily realized by forming the wiring with the printed pattern 51 on the same plane as the control electrode.

Fl and F2 are cathode electrodes; Fl.

Each cathode 2 is connected in series between F2. That is, the number of cathodes and the arrangement of the cathodes are the same as in the conventional example shown in FIG. 8, and the contact resistance between each cathode 2 and the support electrode 50 that supports the cathode 2 also varies as in the conventional technique.

However, since all cathodes are connected in series, the current flowing through each cathode is the same.

Here, the resistance value of the cathode depends on its length,
The variation in length is small. Therefore, the cathode temperature becomes almost constant, and electron emission and variations in brightness are reduced. Connecting cathodes arranged in a matrix in series makes wiring difficult due to the electrode structure, but it can be realized by printing on the substrate lc like the control electrode wiring 5.6. Note that the printed wiring here also includes multilayer printed wiring.

In addition, in the embodiment, an example in which the control electrode is disposed on the back surface of the cathode has been described, but it may be disposed between the cathode and the anode. Furthermore, although the correspondence relationship between the cathode and the pixel is shown as 1:2, it may be in any relationship of 1:1 or 1:n, and various control electrodes may be placed on the substrate IC that forms part of the vacuum container. I have shown this using an example of configuring
It may be constructed on a flat plate provided inside the vacuum container.

(Effects of the Invention) As explained above, according to the present invention, all the linear cathodes arranged in a matrix are connected in series, so that the current flowing through the cathodes can be made constant, and as a result, the cathode Since the temperature can be kept constant, variations in electron emission from the cathode are eliminated, making it possible to obtain high-quality display with little variation in brightness from pixel to pixel.

[Brief explanation of drawings]

Fig. 1 is a cathode connection diagram for explaining the principle of a light source display tube according to an embodiment of the present invention, Fig. 2 is an exploded view and assembly diagram of a fluorescent display element, and Fig. 3 is a diagram showing two types of control wjt. Pole arrangement and wiring diagram, Figure 4 is a timing chart of signals applied to each electrode, Figure 5 is a relationship diagram showing the correspondence between pixel arrangement and electrodes, Figure 6 is the potential of each electrode and the flow of electrons. FIG. 7 is an equivalent circuit around a conventional display tube and a potential relation diagram of each electrode, and FIG. 8 is a cathode connection diagram of a conventional display tube. lc is a substrate, 2... cathode, 4... control t pole, 9
... Phosphor, 50... Support pole, 51... Print pattern, Fl, F2 River cathode scratched. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa Figure 2 Figure 3 Figure 4 Or”r)<
Shi-1 Figure 5 Figure 6 Figure 8

Claims (1)

[Claims] An anode formed by arranging phosphors in a matrix in a vacuum container, a group of directly heated linear cathodes arranged in a matrix at positions facing the anode in correspondence with the phosphors, and 1. A light source display tube having a control electrode group for controlling the flow of electrons, characterized in that the directly heated linear cathodes are connected in series.