JPH0289088A - Driving method for fluorescent display tube - Google Patents

Abstract

PURPOSE:To eliminate the luminance difference between lit and non-lit segments by applying a short pulse voltage to each grid electrode and a segment anode after the scan pulse of each grid electrode, irradiating the surface of a phosphor with an electron beam at intervals of a certain time and eliminating gas molecules stuck to the surface. CONSTITUTION:A pulse voltage 13 is selectively applied to a segment anode P to be displayed, and pulse voltages 111 to 11n are applied to respective grid electrodes G1 to Gn synchronously with this selective application to scan grids. After pulse voltages 111 to 11n applied to respective grid electrodes G1 to Gn, namely, scan pulses, short pulse voltages 121 to 12n and 14 are applied to all of grids G1 to Gn and the segment anode P so that the surface of the phosphor is cleaned, and intra-tube remaining gas molecules stuck to the surface of the phosphor are eliminated. Thus, the luminance difference between lit and non-lit segments is eliminated to obtain stable display for a long time.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for driving a fluorescent display tube, and more particularly to a method for driving a fluorescent display tube to remove residual gas molecules in the tube attached to the surface of the fluorescent material. .

[Conventional technology]

Generally, in a fluorescent display tube, an electron beam emitted from a cando is controlled by a grid electrode, and the electron beam collides with a segment anode to which a positive voltage is selectively applied, stimulating a phosphor coated on the segment anode to emit light. and display predetermined information.

[Problems that the invention attempts to solve]

By the way, in such a fluorescent display tube, as a characteristic of the display tube itself, segments that are lit for a long time,
There is a phenomenon in which a brightness difference occurs between segments that are not lit.

This phenomenon is commonly called Memo+7-Dame. It is known that the cause of this brightness difference is that residual gas molecules in the tube adhere to the surface of the phosphor, reducing its luminous efficiency. In other words, in the non-lit segments, gas molecules adhere and accumulate, reducing the luminous efficiency, while in the lit segments, the phosphor surface is constantly stimulated by the electron beam from the cand, so the phosphor surface is The attached gas molecules separate. Therefore, the surface of the lighting segment is always in a clean state, and the initial luminous efficiency is maintained. As a result, there is a problem in that a difference in brightness occurs between the lit segment and the non-lit segment.

The present invention has been made in view of the above points, and its purpose is to keep the surface of the phosphor in a clean state at all times.
An object of the present invention is to provide a method for driving a fluorescent display tube that eliminates the difference in brightness between lit segments and non-lit segments.

[Means to solve the problem]

In order to achieve the above object, the method for driving a fluorescent display tube according to the present invention provides a method for driving a fluorescent display tube such that at the end or immediately after the scan pulse of each grid electrode, the grid electrode and the segment anode are sufficiently cleaned to clean the phosphor surface. By applying short pulse voltages, the electron beam from the cathode is irradiated onto the surface of the phosphor at regular intervals to remove gas molecules attached to the surface.

[Effect]

Therefore, in the present invention, the surface of the phosphor in the pan is stimulated by the electron beam at regular intervals, so that the gas adhering to the surface of the phosphor is released, keeping the surface always clean. be able to.

〔Example〕

FIG. 1 is a timing chart for explaining one embodiment of the method for driving a fluorescent display tube according to the present invention.
) to (c) show timing charts of pulse voltages applied to the plurality of grid electrodes 01 to Gn, and (d) of the figure shows a timing chart of pulse voltages applied to segment anodes P, respectively. In this embodiment, when driving the fluorescent display tube, the pulse voltage 13 shown in FIG. ,...Gn first
Pulse voltages 11*, 11, shown in figures (,) to (,),
Apply @1■11nt- and perform grid scan,
During the application of each voltage, the segment anode P
The display is performed by stimulating the phosphor coated on the grid with an electron beam from the cathode to emit light, which is similar to the driving method of a normal fluorescent display tube, but each grid electrode G1 + Gt
+...Pulse voltage 11t applied to Gn 11
1. ! 1-... At the end of the 11n scan pulse, each grid electrode G! is used to clean the surface of the phosphor. .

G2 +...Gn and segment anodes P are all supplied with sufficiently short pulse voltages 12x, 12*,...12n and 14 as shown in Fig. 1 (,) to (d), respectively. The gas is applied to remove residual gas molecules in the tube that adhere to the surface of the phosphor. In FIG. 1, Tc is the pulse 121 to 12n, 1 inserted at the end of each scan pulse in order to clean the surface of the phosphor.
4 cycles and t3 represents their pulse width.

As described above, according to the driving method of this embodiment, the cycle Tc t for cleaning the surface of the phosphor, each grid electrode 0
By inserting after the scan pulse of 1 to Gn,
At regular intervals, all phosphor surfaces are stimulated by an electron beam emitted from the cathode. As a result, the gas adhering to the surface of the phosphor is removed, and the surface is always kept clean. As a result, there is no difference in brightness between the lit segment and the non-lit segment as in the conventional case.

Here, each grid electrode 01 to Gn and segment anode P
Pulse voltages 121 to 12n and 14 respectively applied to
The pulse width t3 is set to be shorter than the rise time of the fluorescent material upon incidence of the electron beam, or to be so short that it cannot be seen by the human eye even if it emits light. Further, the number of those pulses is arbitrary and not specified.

Furthermore, the timing of applying a pulse to clean the surface of the phosphor is as shown in FIG.
It may be done immediately after the scan pulse of ~Gn. In this embodiment as well, the same effects as in the embodiment shown in FIG. 1 can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to eliminate the difference in brightness between lit and non-lit segments, provide a stable display for a long time, and have an excellent effect on improving the performance of fluorescent display tubes. .

[Brief explanation of drawings]

FIG. 1 is a timing chart for explaining one embodiment of the present invention, and FIG. 2 is a timing chart for explaining another embodiment of the present invention. 12t, 1h, 1112n, 14 @... Pulse voltage for cleaning the surface of the phosphor.

Claims (1)

[Claims] In a fluorescent display tube, an electron beam from a cathode is controlled by a grid electrode and collides with a segment anode to which a positive voltage is selectively applied, stimulating the phosphor coated thereto to emit light. At the end or immediately after the scan pulse, a sufficiently short pulse voltage is applied to each grid electrode and segment anode to clean the phosphor surface, thereby irradiating the phosphor surface with an electron beam at regular intervals. 1. A method for driving a fluorescent display tube, characterized in that gas molecules adhering to the surface of the fluorescent display tube are removed.