JPH0453990A - Driving method for fluorescent display device - Google Patents

Abstract

PURPOSE:To suppress an erroneous display, what is called a leakage light emission generated in connection with leakage of a thermion by driving two kinds of control electrodes connected in common in the line direction or the row direction for controlling a flow of the thermion by different potential. CONSTITUTION:Different voltages are applied to a scanning electrode 3 and data electrode 4, and to put it concretely, by making the potential of the scanning electrode 3 side small, both control electrodes are driven. That is, a leakage light emission at the time of 'black' display is caused by a fact that the vicinity of a cathode 2 which originally becomes a cut-off state by negative potential of the data electrode 4 becomes an insufficient out-off state since the potential of the scanning electrode 3 is high, a small thermion is attracted to the potential of the scanning electrode 3, and it passes through an opening part of a shielding electrode and comes into collision with a phosphor. Therefore, the potential of the scanning electrode 3 side is made lower than the potential of the data electrode 4 side. In such a way, at the time of 'black' display, surplus potential of the scanning electrode 3 for obstructing the cut-off state by the potential of the data electrode 4 is reduced, a satisfactory cut-off state is obtained, and the leakage light emission is suppressed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for driving a large-screen fluorescent display device used in a stadium, etc., and particularly relates to a method for driving light-emitting elements constituting the fluorescent display device. be.

[Conventional technology]

FIG. 2 is an exploded perspective view showing the general structure of a fluorescent display device, in which 1a is a display portion coated with phosphor 9 in a matrix, 1b is a spacer forming a side surface of the fluorescent display device,
1c is a substrate on which a cathode 2, two types of control electrodes (scanning electrode 3, data electrode 4), their wiring A56, etc. are arranged. The display section 1a, the spacer 1b, and the substrate 1c constitute a vacuum container of the display tube. In the center of the board 1c,
Exhaust port I, which serves as a passage for exhausting the air inside the vacuum container
O is formed. A flat shielding electrode 7 having openings 8 formed in a matrix at positions corresponding to each of the phosphors 9 is provided in the vacuum container.

FIG. 3 shows the arrangement of control electrodes and their wiring patterns on the substrate 1c. In the figure, the horizontal direction is the row direction, and the vertical direction is the column direction. Eight directly heated linear cathodes 2 are formed in two rows, four in each row, a little apart from the surface of the substrate 1c. When each cathode 2 is heated with electricity, thermoelectrons are emitted from each cathode 2. On a portion of the surface of the substrate 10 facing each cathode 2, there is provided one control electrode 8 for controlling thermionic emission from the cathode 2.
data electrodes 4 are formed across two rows and four columns. Each data electrode 4 controls thermionic emission from each corresponding cathode 2 by applying a positive or negative potential to the potential of the cathode 2 . On both sides of each data electrode 4 in the column direction on the surface of the substrate 1c, there are control electrodes 1 that control the traveling direction of the thermoelectrons emitted from the cathode 2.
Six scanning electrodes 3 are formed across four rows and four columns.

Two of the eight data electrodes 4 in the column direction are wired by four data wirings A6 arranged in the column direction, and each data wiring 6 is a data electrode lead-out portion -D.

It is connected to Further, each of the 16 scan electrodes 3 in the row direction is wired by four scan wires 5 arranged in the row direction, and each scan wire 5 is connected to the lead-out portions S, -S of the scan electrodes.
, is connected to.

FIG. 7 shows a conventional equivalent circuit and the potential relationship of each electrode in a fluorescent display device configured as described above. Since the cathode 2 is a directly heated type, alternating current is applied to the cathode 2 so that the potential gradient is canceled out and the brightness is not affected. An equal voltage V is applied to the scanning electrode 3 and the data electrode 4 from a common power source. Note that in the following explanation of the operation, the positive or negative potential applied to the scanning electrode 3 and the data electrode 4 is a potential with respect to the midpoint N of the cathode potential.

Next, the operation will be explained. FIG. 4 shows the timing of the signals applied to the scanning electrode 3 and the data electrode 4, and
The figure shows the arrangement of phosphors 9 in the display section 1a.

The basic principle of display in the fluorescent display device configured as described above is that thermionic electrons emitted from the cathode 2 are accelerated and collided with the phosphor 9 of the display section 1a, thereby exciting the phosphor 9 and causing it to emit light. It is. positive potential of each scanning electrode 3;
The positive and negative potentials of each data electrode 4 are controlled by applied signals as shown in FIG. The combination of potentials at the scanning electrode 3 and the data electrode 4 controls the movement of thermoelectrons and controls the light emission of the phosphor 9 as described below. FIG. 6 shows the combinations of potentials of the re-control electrodes and the flow of thermoelectrons in each combination, and the drawing numbers and symbols are written in correspondence with the numbers and symbols in the explanation below.

■When both the scanning electrode 3 connected in the row direction and the data electrode 4 connected in the column direction are positive with respect to the cathode 2: Thermionic electrons emitted from the cathode 2 due to the positive potential of the data electrode 4 are transferred to the scanning electrode 3, passes through a predetermined opening 8 of the shielding electrode 7, and collides with the phosphor 9. Therefore, in this case, the phosphor 9 emits light.

(2) When the scanning electrode 3 is positive and the data electrode 4 is negative The negative potential of the data electrode 4 near the cathode 2 makes the potential near the cathode 2 negative, suppressing the emission of thermoelectrons. Therefore, in this case, the phosphor 9 does not emit light.

(2) When the scanning electrode 3 is negative and the data electrode 4 is positive There are two cases: secondary.

■-a: When the other scanning electrode 3 is positive, the cathode 2
Thermionic electrons emitted from the scanning electrode 3 are deflected toward the other scanning electrode 3 by the potential of the scanning electrode 3. Therefore, at this time, the phosphor 9
does not emit light.

■-b: When the other scanning electrode 3 is also negative, the potential of the data electrode 4 is positive, but since the area of the data electrode 4 is small, the area near the cathode 2 is affected by the negative potential of the scanning electrodes 3 on both sides. becomes negative and the emission of thermionic electrons is suppressed. Therefore, at this time, the phosphor 9 does not emit light.

(2) When both the scanning electrode 3 and the data electrode 4 are negative: The potential near the cathode 2 becomes negative, and the emission of thermoelectrons is suppressed. Therefore, in this case, the phosphor 9 does not emit light.

As explained above, as can be understood from the wiring relationship shown in FIG. 3 and the arrangement of the phosphors 9 shown in FIG. 5, the scanning electrodes 3 (row electrodes) and the data electrodes 4 ( The phosphors 9 located at the intersections of the column electrodes will emit light. Specifically, first, when a signal is applied to SI, the phosphors pH ~Pt4 are selected, and whether or not they emit light is determined according to the potential of the data electrode 4 applied to ~D4. Then, when a signal is applied to S2, the phosphors P2~
PZ4 is selected, and the presence or absence of light emission is similarly determined according to the potentials of the four data electrodes 4. Hereinafter, when a signal is applied to 53S4, whether or not to emit light is determined in exactly the same manner. In this way, as shown in FIG.
By sequentially applying a scanning signal to the data electrodes 4 and applying an arbitrary data signal to the data electrodes 4, it is possible to control the light emission of each phosphor 9 and obtain an arbitrary display on the display section 1a.

[Problem to be solved by the invention]

Since the conventional fluorescent display device has the above configuration, as is clear from FIG. 4, even when the potentials of the data electrodes 4 are all negative, that is, when displaying "black",
A predetermined scanning voltage is always periodically applied to the scanning electrode 3. Here, the vicinity of the cathode 2 needs to be in a cut-off state due to the influence of the negative potential of the data electrode 4. However, as shown in FIG. 8, due to the positive potential of the scanning electrode 3, some of the thermoelectrons jump out of the cathode 2 and pass through the openings 8 of the three scanning electrodes to which positive voltage was applied. In some cases, the light reaches the phosphor 9. In such a case, a phenomenon called so-called leakage light emission occurs in which the phosphor 9 glows vaguely even though the display is originally "black". Particularly when a large number of light emitting elements of this kind are arranged and used, some elements may exhibit significant leakage of light due to variations in the characteristics of the light emitting elements. As a result, large-screen display devices have the problem that even though they are displaying "black", light leakage occurs everywhere, giving the impression that something is being displayed. be.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for driving a fluorescent display device that can accurately control the flow of thermoelectrons and eliminate erroneous display caused by leaked light emission. do.

[Means to solve the problem]

The method for driving a fluorescent display device according to the present invention is characterized in that two types of control electrodes commonly connected in the row or column direction are driven at different potentials. Specifically, the scanning electrode far from the cathode is characterized in that it is driven at a lower potential than the data electrodes.

[Effect]

In the method for driving a fluorescent display device of the present invention, "black" is produced by driving two types of control electrodes at different potentials.
The scattering of thermoelectrons during display is suppressed, and leakage of light emission is prevented.

〔Example〕

Examples of the present invention will be specifically described below.

FIG. 1 is a diagram showing an equivalent circuit of a fluorescent display device for implementing the present invention and the potential relationship of each electrode. In the figure, ■, is the voltage applied to the scanning electrode 3, V is the voltage applied to the data electrode 4, and ■ is smaller than vtl. Conventionally, an equal voltage V was applied to the scan electrode 3 and the data electrode 4 from a common power source, but in the present invention, different voltages are applied to each electrode, and specifically, the voltage V is applied to each of the three scan electrodes. Both control electrodes are driven by decreasing the potential. In addition,
The basic configuration of the fluorescent display device for implementing the present invention is the same as the configuration shown in FIGS. 2 and 3, so
The explanation will be omitted. Furthermore, since the control operation for controlling whether or not each phosphor 9 emits light is the same as the operation explained in the section of the prior art with reference to FIGS. 4, 5, and 6, the explanation thereof will be omitted. The main objective of the present invention, which is to prevent the occurrence of leakage light emission, will be explained below with emphasis.

As shown in FIG. 8, the leakage light emission during "black" display is caused by the fact that the negative potential of the data electrode 4 should normally result in a cut-off state. This is caused by the off state, where a few thermoelectrons are attracted to the potential of the scanning electrode 3, pass through the opening 8 of the shielding electrode 7, and collide with the phosphor 9.

Here, as shown in FIG. 1, by lowering the potential of the three scanning electrodes compared to the potential of the data electrode 4 side, "black" is produced.
During display, the extra potential of the scanning electrode 3 that interferes with the cut-off state due to the potential of the data electrode 4 is reduced, a good cut-off state can be obtained, and leakage light emission can be suppressed.

On the other hand, in a display other than "black", thermoelectrons are emitted from the cathode 2 due to the potential of the data electrode 4. here,
A positive potential is periodically applied to the scanning electrode 3,
In order to obtain a normal light emission state, it is necessary to satisfy the following two points.

(2) It is necessary that the scanning electrode 3 on the positive side sufficiently attracts thermoelectrons and allows the thermoelectrons to reach the phosphor 9.

(2) It is necessary for the scanning electrode 3 on the negative side to sufficiently repel the thermoelectrons and block the thermoelectrons.

Here, lowering the potential of the scanning electrode 3 as in the present invention is considered to be inconvenient because of the condition (2) mentioned above. However, near the scanning electrode 3 on the positive side, the shielding electrode 7
Since the scanning electrode 3 is influenced by the anode voltage through the opening 8, even if the potential of the scanning electrode 3 becomes somewhat low, the potential condition that is sufficient to attract thermoelectrons is satisfied, and there is no riverbank problem. Regarding the condition (2) above, the condition under which the scanning electrode 3 repels thermoelectrons depends on the cutoff potential, that is, the negative potential of the scanning electrode 3 with respect to the midpoint potential of the cathode 2. Even if the positive potential of the scanning electrode 3 is changed as in the present invention, the cutoff potential does not change as shown in FIG. 1, and there is no river bank problem.

As described above, even if the potential of the scanning electrode 3 is set low as in the present invention, there is no adverse effect on normal display control. In addition, according to the present invention, it is possible to perform excellent control of thermoelectrons so that leakage light does not occur during "black" display.

〔Effect of the invention〕

As described in detail above, according to the present invention, the two types of control electrodes commonly connected in the row or column direction that control the flow of thermionic electrons are driven at different potentials, so that thermionic leakage The present invention exhibits excellent effects, such as being able to suppress erroneous display, so-called leakage light emission, that occurs due to this, and making it possible to display high-quality images with good contrast.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an equivalent circuit and the potential of each electrode of a fluorescent display device for implementing the present invention, FIG. 2 is a diagram showing the overall configuration of the fluorescent display device, and FIG. 3 is a diagram showing two types of control electrodes and Figure 4 is a diagram showing the wiring, Figure 4 is a diagram showing the timing of signals applied to both control electrodes, Figure 5 is a diagram showing the arrangement of phosphors, and Figure 6 is a diagram showing the potential of both control electrodes and the flow of thermoelectrons. FIG. 7 is a diagram showing an equivalent circuit and the potential of each electrode in the prior art, and FIG. 8 is a diagram showing a state in which leakage light emission occurs. 1a...Display section 2...Cathode 3...Scanning electrode (control electrode) 4...Data electrode (control electrode)
9... Phosphor In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A display section coated with a phosphor in a matrix, a plurality of cathodes arranged opposite to the display section, and connected in common in each of the row and column directions, and the flow of thermoelectrons from the cathodes. 1. A method for driving a fluorescent display device comprising two types of control electrodes in a vacuum container, the method comprising driving the two types of control electrodes at different potentials.