JP2908137B2 - Driving method of fluorescent display tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a fluorescent display tube.

[0002]

2. Description of the Related Art A conventional method for driving a fluorescent display tube driven by static driving is shown in FIG.
As shown in FIG. 2, a grid 17 for accelerating and controlling thermoelectrons emitted from a filament (not shown) is always supplied with an on-potential by a grid power supply 4. Via the phosphor segment selection circuit 1 only.

[0003]

As shown in FIG. 5, the conventional fluorescent display tube has a structure in which the phosphor segments 6 to 11 have o
The grid 17 is always on regardless of the n and off potentials.
Potential is applied. Continuous filament and grid 17
Since there is a potential difference between the filaments, thermoelectrons are always emitted from the filament. The degree of deterioration of the electron emission ability of the filament is determined by the temperature of the filament, the amount of electrons extracted by the potential difference from the grid 17, and the time during which electron emission is performed. Therefore, when the on potential is constantly applied to the grid 17, the deterioration of the electron emission capability of the filament is accelerated, and the amount of electron emission from the filament is reduced. As a result, the phosphor segment 6
In this case, the number of electrons incident on .about.11 decreased, and the emission luminance was reduced, and the life was terminated.

[0004] Also, only some phosphor segments are o
Even when the potential does not reach the n potential, the on potential is applied to the entire grid 17, so that there is a problem that power consumption increases.

[0005]

The driving method of a fluorescent display tube of the present invention According to an aspect of the grid is divided into a plurality in accordance with the pattern of the phosphor segment on the anode substrate, phosphor segments election
When all the phosphor segments in each grid are at the off potential by using the selection circuit and the grid selection circuit, the voltage applied to the grid is set to the off potential.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a driving circuit for a fluorescent display tube according to a first embodiment of the present invention. In driving the fluorescent display tube, first, in the fluorescent display tube 5, the phosphor segments 6, 7
And phosphor segments 8, 9 and phosphor segments 10, 1
The area is divided into 1 and the grid is divided. Next, the outputs a to f of the phosphor segment selection circuit 1 are connected to the respective phosphor segments 6 to 11 of the fluorescent display tube 5. Next, the on / off data signals a 'to f' of the outputs a to f of the phosphor segment selection circuit 1 are input to the OR circuits a ', b' and c ', d' and e ', f', respectively. The output of the OR circuit is connected to the input terminals 1 ', 2', 3 'of the grid selection circuit 3. The grid selection circuit 3 turns on and off the input signals of the input terminals 1 ′, 2 ′, 3 ′, and outputs the on potential to each of the grids 12, 13, 14 via the output terminals 1, 2, 3.
An off potential is applied.

FIG. 2 is a timing chart of this embodiment. When all the phosphor segments in each of the grids 12 to 14 are at the off potential, the grid is at the off potential.

FIG. 3 is a block diagram of a driving circuit of a fluorescent display tube according to a second embodiment of the present invention. The present embodiment is a driving circuit of the fluorescent display tube when the ON potentials of the phosphor segments 6 to 11 and the grids 12 to 14 are equal, and has an advantage that the grid selection circuit 3 can be simplified as shown in the figure.

[0009]

As described above, according to the present invention, the grid is divided in accordance with the pattern shape of the phosphor segments, and the driving method of setting the grid applied voltage in which all the phosphor segments in each grid have the off potential to the off potential. As a result, the current of the grid is reduced by the time when each grid is at the off potential, and the power consumption is also reduced.

The degree of deterioration of the electron emission capability of the filament is determined by the temperature of the filament, the amount of electrons extracted by the potential difference from the Grigg, and the time during which electron emission is performed. The electron emission time of the filament can be reduced, and the deterioration of the electron emission ability of the filament can be delayed. As a result, it is possible to suppress a decrease in the amount of electrons incident on the phosphor segment,
A decrease in fluorescent luminance can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram of a drive circuit according to a first embodiment of the present invention.

FIG. 2 is a timing chart showing a driving method according to the first embodiment.

FIG. 3 is a block diagram of a drive circuit according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a conventional driving circuit for a fluorescent display tube.

FIG. 5 is a timing chart showing a conventional driving method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Phosphor segment selection circuit 3 Grid selection circuit 12 Grid 1 13 Grid 2 14 Grid 3

Claims (1)

(57) [Claims] An anode substrate having a patterned phosphor segment; a filament for emitting thermoelectrons;
In a statically driven fluorescent display tube comprising a grid for accelerating and controlling the thermoelectrons and a cover glass sealed to the anode substrate to form a vacuum vessel, the grid is formed by patterning the phosphor segments of the anode substrate. According to the above, the phosphor segment selection circuit and the grid
A driving method for a fluorescent display tube, characterized in that when all phosphor segments in each grid have an off potential using a selection circuit, the grid is set to an off potential.