JP2566450B2 - Driving method for fluorescent display tube - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for driving a fluorescent display tube, and more particularly to a driving method for removing residual gas molecules in the tube attached to the fluorescent display.

[Conventional technology]

In general, a fluorescent display tube controls an electron beam emitted from a cathode by a grid electrode, causes the electron beam to collide with a segment anode to which a positive voltage is selectively applied, and stimulates a fluorescent substance applied to the segment anode to emit light. Then, the predetermined information is displayed.

[Problems to be Solved by the Invention]

By the way, in such a fluorescent display tube, as a characteristic of the display tube itself, there is a phenomenon that a brightness difference occurs between a segment which is illuminated for a long time and a non-illuminated segment. This phenomenon is commonly known as memory dim.
As a cause of this brightness difference, it is known that the residual gas molecules in the tube adhere to the surface of the fluorescent substance and reduce the luminous efficiency thereof. That is, gas molecules are deposited and deposited on the non-lighted segment to reduce the luminous efficiency, and conversely, the lighted segment continuously stimulates the surface of the fluorescent body with the electron beam from the cathode, so The attached gas molecules are released. 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 that a brightness difference occurs between the lighted segment and the non-lighted segment.

The present invention has been made in view of the above points, and an object thereof is to keep the surface of the fluorescent body in a clean state at all times, thereby eliminating the brightness difference between the lit segment and the non-lit segment of the fluorescent display tube. It is to provide a driving method.

[Means for solving the problem]

In order to achieve the above object, the driving method of the fluorescent display tube according to the present invention, the last or immediately after the scan pulse of each grid electrode, to each grid electrode and segment anode to clean the phosphor surface, By repeatedly applying a sufficiently short pulse voltage that is not visually recognizable, an electron beam is applied to the surface of the fluorescent body at regular intervals to remove gas molecules adhering to the surface. .

[Action]

Therefore, in the present invention, since all the fluorescent substance surface is stimulated by the electron beam at regular intervals, the gas adhering to the fluorescent substance surface is released, and the surface is always kept in a clean state. Can be kept.

〔Example〕

FIG. 1 is a timing chart for explaining an embodiment of a method for driving a fluorescent display tube according to the present invention, and FIGS. 1 (a) to (c) show pulses applied to a plurality of grid electrodes G _{1 to} Gn. The timing chart of the voltage is shown, and the timing chart of the pulse voltage applied to the segment anode P is shown in FIG. In this embodiment, when the fluorescent display tube is driven, the pulse voltage 13 shown in FIG. 1 (d) is selectively applied to the segment anode P to be displayed, and the grid electrodes G ₁ and G are synchronized with it. ₂ , ... Gn in Fig. 1 (a) ~
Pulse voltage 11 ₁ shown in (c), 11 _2, performs Guritsudosukiyan by applying · · · · · 11n, while being applied respective voltages, cathode fluorescent body that is applied to the segment anode P The point of displaying by stimulating light emission with an electron beam is similar to the driving method of a normal fluorescent display tube,
The pulse voltage applied to each grid electrode G ₁ , G ₂ , ... Gn 11 ₁ , 11 ₂ , ... 11n, that is, each grid electrode for cleaning the fluorescent substance surface at the end of the scanning pulse.
G ₁ , G ₂ , ・ ・ ・ ・ ・ Gn and segment anode P are all first
A sufficiently short pulse voltage as shown in Figures (a) to (d)
12 ₁ , 12 ₂ , ... 12n and 14 are applied respectively to remove residual gas molecules in the tube adhering to the surface of the phosphor. In the first view, Tc is to the phosphor surface to clean, pulses 12 ₁ ～12N to be inserted at the end of each Sukiyanparusu represents a cycle of 14, t _S represents their pulse width .

As described above, according to the driving method of the present embodiment, the cycle Tc for cleaning the surface of the fluorescent body is set to the grid electrodes G ₁ to
By inserting after the scanning pulse of Gn, all the phosphor surfaces are stimulated by the electron beam emitted from the cathode at regular intervals. As a result, the gas adhering to the surface of the phosphor is released, and the surface is always kept clean. As a result, the brightness difference between the illuminated segment and the non-illuminated segment does not occur unlike the conventional case.

Here, pulse widths of pulse voltages 12 _{1 to} 12n and 14 applied to the grid electrodes G _{1 to} Gn and the segment anode P, respectively.
The time t _S is set to be shorter than the fluorescent rise time of the fluorescent body when an electron beam is incident on the fluorescent body, or a short time which cannot be visually recognized by the human eye even when light is emitted. Moreover, the number of those pulses is arbitrary and is not specified.

Further, as shown in FIG. 2, the timing of applying the pulse for cleaning the surface of the fluorescent body is set to each grid electrode G ₁
It may be right after the scan pulse of ~ Gn. Also in this embodiment, the same effect as that of the embodiment of FIG. 1 can be obtained.

〔The invention's effect〕

As described above, according to the present invention, it is possible to eliminate the difference in brightness between the lighted and non-lighted segments, obtain stable display for a long time, and have an excellent effect of improving the performance of the fluorescent display tube.

[Brief description 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. 12 ₁ , 12 ₂ , ・ ・ ・ ・ ・ 12n, 14 ...... Pulse voltage to clean the surface of the phosphor.

Claims (1)

(57) [Claims] 1. A fluorescent display tube in which an electron beam from a cathode is controlled by a grid electrode to collide with a segment anode to which a positive voltage is selectively applied, and a fluorescent substance applied to the segment anode is stimulated to emit light for display. , At the end or shortly after the scan pulse of each grid electrode,
By repeatedly applying a sufficiently short pulse voltage that is not visually recognized to each of the grid electrodes and the segment anodes to clean the surface of the fluorescent material, the surface of the fluorescent material is irradiated with an electron beam at regular intervals. A method for driving a fluorescent display tube, which comprises removing gas molecules adhering to the surface.