JP2010181517A - Method for driving vacuum fluorescent display, and vacuum fluorescent display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the luminance life of a vacuum fluorescent display that is driven according to a dynamic drive scheme and that uses a phosphor having remarkable luminance saturation. <P>SOLUTION: The method for driving the vacuum fluorescent display is provided, which comprises allowing a phosphor layer formed on an anode to display under low-energy electron excitation by dynamic driving, wherein the phosphor included in the phosphor layer is a phosphor in which the luminance increases when a pulse width is reduced under conditions in which the Du is kept the same in the dynamic driving, and in which, after a voltage is applied to the anode and the luminance of the phosphor is saturated, the time at which the luminance value decreases to 10% of the saturation luminance value following stoppage of the voltage application is 200 μsec or more. By the dynamic driving, the pulse width and the pulse repetition period are made variable in the direction of maintaining the initial luminance of the phosphor as driving time elapses. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fluorescent display tube driving method and a fluorescent display tube using the driving method.

In addition to ZnO: Zn (green) exhibiting excellent light emission characteristics as phosphors for low-energy electron beam excitation such as fluorescent display tubes, SrTiO ₃ : Pr (red), CaTiO ₃ : Pr (red), Gd ₂ O ₂ S : Eu (red), Y ₂ O ₂ S: Eu (red), La ₂ O ₂ S: Eu (red), SnO ₂ : Eu (orange), ZnS: Mn (orange), ZnGa ₂ O ₄ (blue) Many phosphors in which a conductive substance such as In ₂ O ₃ is added to ZnGa ₂ O ₄ : Mn (green) have been studied and developed (Non-patent Document 1).
However, many phosphors that have been developed as phosphors for low-energy electron beam excitation have short lifetimes other than green-emitting ZnO: Zn.

On the other hand, a dynamic driving method is known as a driving method of a fluorescent display tube. In this dynamic drive, when the duty cycle (hereinafter abbreviated as Du) expressed as the ratio (t _p / T) between the pulse width t _p and the pulse repetition period T is constant, Even if the pulse width t _p is changed, the luminance is substantially the same. However, in the case of a phosphor having a slow response speed, the luminance is lowered when the pulse width t _p is shortened. Therefore, dynamic driving using a phosphor having a slow response speed in order to obtain a required luminance is considered disadvantageous (Patent Document 1, Non-Patent Document 2).
For this reason, when using a phosphor with a slow response speed, the repetition period T is set to 8 to 20 msec while avoiding shortening the repetition period T of the pulse more than necessary (that is, shortening the pulse width). For example, when Du = 1/10 to 1/50 and T = 10 msec, the pulse width is driven with a relatively long pulse width of 200 to 1000 μsec.

As a method for improving the luminance life of a phosphor in dynamic driving, a method described in Patent Document 2 is known. This method is intended to prevent brightness unevenness from occurring in parallel with the cathode as the usage time elapses, particularly in a fluorescent display tube having a rib / grid electrode. At least one of the anode and the grid is used. Adjust at least one of the pulse width and voltage of the drive pulse to be applied in relation to the distance from the cathode to the anode, and adjust the amount of adjustment of the pulse width and voltage in relation to the distance from the cathode as the cumulative action time increases. It is a method of enlarging.
Further, a driving voltage necessary for driving the fluorescent display tube is supplied, and a driving means for dynamically driving the fluorescent display tube by the driving voltage, a temperature detecting means for detecting an operating environment temperature of the driving means, Voltage varying means capable of varying the anode voltage supplied to the anode electrode of the fluorescent display tube among the driving voltages to a required voltage value according to the temperature detection result of the temperature detecting means. A fluorescent display tube driving device is known (Patent Document 3).
However, as the various phosphors have been developed as phosphors for low-energy electron beam excitation, and the fluorescent display tube using these phosphors has been put into practical use, the above improvement method except for the green-emitting ZnO: Zn phosphor is used. However, there are many phosphors with low brightness and short life, and further higher brightness and longer life are required.

JP 2000-250454 A JP 2003-195818 A Japanese Patent Laid-Open No. 11-95712

Edited by Takao Kishino, 56 pages of fluorescent display tubes, published by Sangyo Tosho Co., Ltd. Edited by Takao Kishino, 155 pages of fluorescent display tubes, published by Sangyo Tosho

  The present invention has been made to cope with such a problem, and a driving method capable of improving the luminance life of a fluorescent display tube using a phosphor driven by a dynamic driving method and having remarkable luminance saturation, and the driving method. An object of the present invention is to provide a fluorescent display tube driven by the

A driving method of the present invention is a driving method of a fluorescent display tube that displays a phosphor layer formed on an anode electrode under low-energy electron beam excitation by dynamic driving,
The phosphor included in the phosphor layer is a phosphor whose luminance is improved when the pulse width is shortened under the same Du condition under dynamic driving, and a voltage is applied to the anode electrode, A phosphor whose time to decrease to a luminance value of 10% of the saturated luminance value after the voltage application is stopped after the luminance is saturated is 200 μsec or more;
The dynamic drive is characterized in that the pulse width and the pulse repetition period are made variable as the drive time elapses in a direction to maintain the initial luminance of the phosphor.
Further, making the pulse width and the pulse repetition period variable as the driving time elapses is characterized in that the anode voltage, grid voltage, and Du are maintained while maintaining the values at the start of driving.

In the driving method of the present invention, the phosphor is a phosphor having a localized emission center.
The phosphor is a phosphor having at least one emission center of a transition metal ion emission center and a rare earth ion emission center. In particular, the emission center is Mn ion, Pr ion, Eu ion, or Tb ion, and phosphors having these emission centers are ZnS: Mn, ZnGa ₂ O ₄ : Mn, SrTiO ₃ : Pr, CaTiO ₃ : Pr. Gd ₂ O ₂ S: Eu, Y ₂ O ₂ S: Eu, ZnGa ₂ O ₄ , Gd ₂ O ₂ S: Tb, Y ₂ O ₃ : Eu, La ₂ O ₂ S: Eu, SnO ₂ : Eu, It is at least one phosphor selected from Zn ₂ SiO ₄ : Mn and CaS: Mn.

The fluorescent display tube of the present invention is a fluorescent display tube that emits light by projecting a low-energy electron beam onto a phosphor layer formed in a vacuum vessel, and the phosphor layer is ZnS: Mn, ZnGa ₂ O ₄ : Mn, SrTiO ₃ : Pr, CaTiO ₃ : Pr, Gd ₂ O ₂ S: Eu, Y ₂ O ₂ S: Eu, ZnGa ₂ O ₄ , Gd ₂ O ₂ S: Tb, Y ₂ O ₃ : Eu, La ₂ The phosphor layer includes at least one phosphor selected from O ₂ S: Eu, SnO ₂ : Eu, Zn ₂ SiO ₄ : Mn, and CaS: Mn, and the phosphor layer has a driving time while maintaining the same Du. It is characterized in that light emission display is performed by a dynamic drive method in which the pulse width and the pulse repetition period are shortened as time passes.

The driving method of the present invention uses a phosphor having a remarkable luminance saturation, and maintains the initial luminance of the phosphor in the direction of maintaining the initial luminance of the phosphor with the same Du as the pulse width and the repetition period of the pulse. Since it is variable, a decrease in luminance can be greatly suppressed and the life of the fluorescent display tube can be extended.
Although it is possible to increase the luminance even if the anode voltage, the grid voltage, or Du is increased as the driving time elapses, such an operation increases the energy of electrons colliding with the phosphor or the number of electrons. Since the increase is caused, the deterioration of the phosphor is accelerated, and the luminance cannot be corrected. In addition, power consumption is increased. On the other hand, in the case of the driving method of the present invention, the luminance can be increased without changing the operation conditions, so that the deterioration of the phosphor is not accelerated and the power consumption of the fluorescent display tube does not increase.

It is sectional drawing of a fluorescent display tube. It is a timing chart figure in a dynamic drive method. It is a figure which shows Du dependence of the luminous efficiency in ZnO: Zn fluorescent substance. It is a figure which shows Du dependence of the luminous efficiency in ZnS: Mn fluorescent substance. SrTiO _3: is a diagram showing the pulse width dependency of the emission efficiency of Pr phosphor. Gd ₂ O ₂ S: is a diagram showing the pulse width dependency of the emission efficiency of the Eu phosphor. CaTiO _3: is a diagram showing the pulse width dependency of the emission efficiency of Pr phosphor. It is a figure which shows the pulse width dependence of the luminous efficiency of ZnS: Mn fluorescent substance. ZnGa ₂ O _4: is a diagram showing the pulse width dependency of the emission efficiency of Mn phosphor. It is a diagram showing the pulse width dependency of the luminous efficiency of the ZnGa ₂ O ₄ phosphor. Y ₂ O ₂ S: is a diagram showing the pulse width dependency of the emission efficiency of the Eu phosphor. It is a figure which shows the pulse width dependence of the luminous efficiency of ZnS: Mn fluorescent substance. It is a figure which shows the pulse width dependence of the luminous efficiency of ZnO: Zn fluorescent substance. It is a figure which shows the pulse width dependence of the luminous efficiency of ZnS: Zn fluorescent substance. It is a figure which shows the pulse width dependence of the luminous efficiency of ZnS: Cu, Al fluorescent substance. It is a figure which shows the pulse width dependence of the luminous efficiency of ZnCdS: Ag fluorescent substance. It is a figure which shows the pulse width dependence of the anode current in ZnO: Zn fluorescent substance. It is a figure which shows the pulse width dependence of the anode current in ZnS: Mn fluorescent substance. Rise time t _r of the light emitted from the phosphor _is a diagram showing the fall time t _f. It is a figure which shows the luminance lifetime of a ZnS: Mn fluorescent substance. CaTiO _3: is a diagram showing the luminance lifetime of Pr phosphor. Gd ₂ O ₂ S: is a diagram showing the luminance lifetime of Eu phosphor. SrTiO _3: is a diagram showing the luminance lifetime of Pr phosphor. ZnGa ₂ O _4: a diagram showing the luminance lifetime of Mn phosphor.

The driving method of the present invention relates to a dynamic driving method of a fluorescent display tube. FIG. 1 is a cross-sectional view of a fluorescent display tube.
The fluorescent display tube 1 includes phosphor layers 6 respectively formed on a plurality of anodes 5 on the display surface of the anode substrate 7, and is generated from a cathode 9 positioned above the phosphor layer 6 in a vacuum space. In this display tube, the plurality of phosphor layers 6 are selectively emitted by controlling the electrons with a plurality of grid electrodes 8 provided between the phosphor layers 6 and the cathode 9.
In FIG. 1, 2 is a glass substrate, 3 is a wiring layer formed on the glass substrate, 4 is an insulating layer, and 4a electrically connects the wiring layer 3 and the anode electrode 5. It is a through hole. Further, 10 is a face glass and 11 is a spacer glass.

The dynamic driving method will be described with reference to FIG. FIG. 2 is a timing chart in the dynamic driving method.
In the dynamic driving method, scanning is performed by sequentially applying an acceleration voltage higher than the potential of the cathode 9 as a pulse voltage of a digit signal (grid scan) to the plurality of grid electrodes 8 (G _{1 to} G _n ). A driving method in which a lighting voltage higher than the potential of the cathode 9 is selectively applied to a predetermined anode 5 as a pulse voltage of an ON (positive) or OFF (negative) segment signal in synchronization with It is. FIG. 2 represents arithmetic numbers in the segments ag. According to such a dynamic driving method, the grid electrode 8 is divided and provided for each predetermined light emitting unit (light emitting group), while the one having a predetermined position predetermined for each light emitting unit among the plurality of anodes 5 is provided. Are connected to a common anode wiring, and the grid electrode 8 functions as a digit selection electrode and the anode 5 functions as a segment selection electrode.
In FIG. 2, T is a repetition period having T _{1 to} T _n as a period, t _p is a pulse width, and t _b is a blanking time. Du is defined as the ratio of t _p to T (t _p / T).

In the above dynamic driving method, the Du dependency is remarkably different depending on the type of phosphor for low-energy electron beam excitation. For example, FIG. 3 shows the Du dependence of the luminous efficiency in a ZnO: Zn phosphor, and FIG. 4 shows the Du dependence of the luminous efficiency in a ZnS: Mn phosphor. The light emission efficiency of the ZnO: Zn phosphor hardly changes even if Du changes, that is, the incident current to the phosphor increases or decreases. On the other hand, in the ZnS: Mn phosphor, when the Du becomes large, that is, when the incident current to the phosphor is increased, the light emission efficiency is greatly reduced.
Since the response speed of the ZnS: Mn phosphor is slow, the conventional dynamic drive is driven with a relatively long pulse width of 200 to 1000 μsec so as to rise as much as possible.

However, ZnS: Mn phosphor, etc., certain phosphors when Du is shorter the pulse width t _p even when the same, so far it has been considered significant luminance contrary (luminous efficiency) The inventor has found that it rises.
Since the brightness of ZnS: Mn phosphors and the like can be significantly improved by shortening the pulse width under a predetermined Du condition, the initial brightness can be maintained by changing the pulse width over time. Can do. In addition, when the same luminance is obtained, the driving voltage can be lowered, so that the life of the fluorescent display tube can be extended. The present invention is based on such knowledge.

The measurement result about the pulse width dependence of luminous efficiency is shown in FIGS. 5 to 12 are examples of the phosphor emission efficiency and to shorten the pulse width t _p is increased, in the example of FIGS. 13 to 16 is a phosphor emission efficiency by changing the pulse width t _p is not changed is there.
The said measurement was measured with the following method. After applying various low-speed electron beam phosphors on the carbon anode of the fluorescent display tube, the tube was formed into a tube by a known fluorescent display tube manufacturing process. ZnO: The phosphor other than Zn, the high conductivity In ₂ O ₃ were mixed for about 10% by weight relative to the total weight of the phosphor and the In ₂ O ₃ in order to prevent charge-up. In a state where the filament cathode was energized and heated to about 650 ° C., the anode / grid electrode (ebc) was set to 50 V _pp , and the light emission efficiency characteristics were measured by changing Du and the pulse width t _p .
The luminous efficiency was expressed as a relative value by measuring the luminance and setting the luminance value with a pulse width t _p of 250 μsec as 100.

As shown in FIGS. 5 to 12, the phosphors are SrTiO ₃ : Pr (FIG. 5), Gd ₂ O ₂ S: Eu (FIG. 6), CaTiO ₃ : Pr (FIG. 7), ZnS: Mn (FIG. 8). In the case of ZnGa ₂ O ₄ : Mn (FIG. 9), ZnGa ₂ O ₄ (FIG. 10), and Y ₂ O ₂ S: Eu (FIG. 11), the light emission efficiency is greatly improved when the pulse width is shortened. Further, ZnS anode grid electrode (ebc) is an example of a case of 35V _pp: an example of Mn are shown in Figure 12, also the anode grid electrode (ebc) is at a lower 35V _pp than 50 V _pp, the pulse width When it is shortened, the luminous efficiency is greatly improved.

On the other hand, as shown in FIGS. 13 to 16, the phosphors are ZnO: Zn (FIG. 13), ZnS: Zn (FIG. 14), ZnS: Cu, Al (FIG. 15), ZnCdS: Ag (CdS, 70% by weight). ) (FIG. 16), even if the pulse width is shortened, the light emission efficiency is not improved and no dependence on the pulse width is observed. This tendency was the same even when the anode / grid electrode (ebc) was 35 V _pp .

  In the measurements shown in FIGS. 5 to 16, the pulse width (period) is changed, but since the anode / grid electrode (ebc) and Du are the same, the current flowing into the phosphor (anode current) is substantially the same. It is constant. Therefore, the dependency on luminous efficiency is the same as the dependency on luminance. FIG. 17 shows the pulse width dependence of the anode current in the ZnO: Zn phosphor, and FIG. 18 shows the pulse width dependence of the anode current in the ZnS: Mn phosphor. In each case, the anode current depends on the pulse width. Absent.

In a dynamic drive, when comparing a phosphor whose luminous efficiency increases when the pulse width t _p is shortened with a phosphor that does not show pulse width dependency, the former mainly includes at least transition metal ion emission centers and rare earth ion emission centers. It can be seen that the phosphor has a localized emission center having one emission center, and the latter is a phosphor having a non-local emission center.

Table 1 and Table 1 show the results of investigating the decreasing tendency of the saturation luminance value after the voltage application was stopped after applying the pulse voltage of the input waveform shown in FIG. It shows in Table 2.
Figure 19 is a diagram illustrating a rise time of emission of the phosphor t _r and fall time t _f after the application of a voltage is stopped at the time of applying a pulse voltage to the anode of the fluorescent display tube. Input waveform anode grid electrode (ebc) is 50 V _pp, the pulse width _{t p} is 1 msec, the time was measured to decrease to 10% of the saturated luminance value as the "fall time _{t f."}

As shown in Table 2, the fall time of the phosphor group is not shown the pulse width dependency whereas the less 100 .mu.sec, as shown in Table 1, the luminous efficiency and to shorten the pulse width t _p increases The fall time of the phosphor group is at least 290 μsec.
The phosphor that can be used in the present invention is a phosphor whose luminance is improved when the pulse width is shortened in the same Du of dynamic drive, and a phosphor whose fall time exceeds 100 μsec, and preferably the fall time is 200 μsec or more. More preferably, the phosphor has a fall time of 290 μsec or more. The phosphor exhibiting such characteristics is a phosphor having a localized emission center mainly having at least one emission center of a transition metal ion emission center and a rare earth ion emission center. The emission center is preferably Mn ion, Pr ion, Eu ion, or Tb ion.

As specific examples, ZnS: Mn phosphor (orange), ZnGa ₂ O ₄ : Mn (green), SrTiO ₃ : Pr (red), CaTiO ₃ : Pr (red), Gd ₂ O ₂ S: Eu (red) Y ₂ O ₂ S: Eu (red), Y ₂ O ₃ : Eu (red), ZnGa ₂ O ₄ (blue), La ₂ O ₂ S: Eu (red), SnO ₂ : Eu (orange), Zn ₂ SiO ₄ : Mn (green), Gd ₂ O ₂ S: Tb (green), CaS: Mn (orange) and the like.

Phosphor that can be used in the present invention, due to the low transition probability from it and the excited state the number of luminescent centers is small in the electron beam excitation region to the ground state, long pulse width t _p in the excitation and emission process saturation tendency As a result, the luminance (luminous efficiency) decreases. On the contrary, it is considered that when the pulse width t _p is short, the luminance (luminous efficiency) is relatively increased.

The dynamic drive of the present invention uses the above phosphor group in which the luminance is improved when the pulse width t _p is shortened under the same Du. Since the pulse width is the brightness is improved short, using such a phosphor, in a direction to maintain the initial brightness, and varying the pulse width t _p and the pulse repetition period T with the passage of driving time.
Since it is often the brightness of the phosphor to be reduced with the lapse of driving time, specifically, shorter than t _p and T of the driving start of the pulse width t _p and the pulse repetition period T with the passage of driving time .

Shortening t _p and T is performed while maintaining Du identity. The anode voltage and grid voltage are maintained while maintaining both voltages at the start of driving.
To shorten the t _p and T with the passage of driving time, for example a driving cumulative time in a nonvolatile memory provided in the drive circuit of the fluorescent display tube integrated holding, in consideration of the type and the turn-on rate of the phosphor It can be set by a known method so that the pulse width and period are changed by the controller after a predetermined time has elapsed.
By satisfying these conditions, the dynamic driving of the present invention can increase the energy of electrons colliding with the phosphor, increase the number of electrons, and increase the power consumption. Corrections can be made. Furthermore, since there is no increase in the energy of electrons and the increase in the number of electrons, deterioration of the phosphor is not accelerated and the life of the fluorescent display tube is improved. Also, power consumption does not increase.

Example 1 and Comparative Example 1
After applying a phosphor in which 10% by weight of In ₂ O ₃ was added to ZnS: Mn (orange) on the carbon anode of the fluorescent display tube, tube formation was performed in a known fluorescent display tube manufacturing process.
Using the obtained fluorescent display tube, the anode and grid electrode (ebc) was lit at 50 Vpp and Du was 1/60, and the luminance maintenance rate was measured. The results are shown in FIG.
Comparative Example 1 is a conventional driving method, and the luminance maintenance rate of the fluorescent display tube was measured while fixing the pulse width tp to 250 μs and the repetition period T to 15 msec.
In Example 1, the pulse width tp at the start of lighting was set to 250 μs and the repetition period T was set to 15 msec. As the lighting time passed, the condition of Du 1/60 was maintained, and tp and T were shortened, respectively. . Table 3 shows the values of tp and T that were changed after the elapse of each time.
As shown in FIG. 20, compared with the comparative example 1 which greatly reduced the initial luminance, the initial luminance was able to be maintained in the example 1.
In addition, after 170 hours from the start of lighting, the luminance maintenance rate was changed from 87% to 97% in Comparative Example 1, from 79% to 102% after 530 hours, and from 75% to 95% after 1000 hours. In each case, the luminance maintenance rate of Example 1 was improved.

Example 2 and Comparative Example 2
After applying a phosphor in which 10% by weight of In ₂ O ₃ was added to CaTiO ₃ : Pr (red) on the carbon anode of the fluorescent display tube, tube formation was performed in a known fluorescent display tube manufacturing process.
Using the obtained fluorescent display tube, the anode and grid electrode (ebc) was lit at 50 Vpp and Du was 1/60, and the luminance maintenance rate was measured. The results are shown in FIG.
Comparative Example 2 is a conventional driving method, and the luminance maintenance rate of the fluorescent display tube was measured with the pulse width tp fixed at 250 μs and the repetition period T fixed at 15 msec.
In Example 2, the pulse width tp at the start of lighting was set to 250 μs and the repetition period T was set to 15 msec. However, as the lighting time passed, the condition that Du was 1/60 was maintained, and tp and T were shortened, respectively. . Table 3 shows the values of tp and T after the elapse of each time.
As shown in FIG. 21, compared to Comparative Example 2 that greatly reduced the initial luminance, Example 2 showed less decrease in the initial luminance.
In addition, after 48 hours from the start of lighting, the luminance maintenance rate is changed from 75% to 91% of Comparative Example 2, and after 170 hours, the luminance maintenance rate is changed from 60% to 84% of Comparative Example 2 after 530 hours. In Example 2, the luminance maintenance rate was improved from 52% to 80%, and from 1000% to 46% after 1000 hours.

Example 3 and Comparative Example 3
After applying a phosphor in which 14% by weight of In ₂ O ₃ was added to Gd ₂ O ₂ S: Eu (red) on the carbon anode of the fluorescent display tube, tube formation was performed in a known fluorescent display tube manufacturing process.
Using the obtained fluorescent display tube, the anode and grid electrode (ebc) was lit at 50 Vpp and Du was 1/60, and the luminance maintenance rate was measured. The results are shown in FIG.
Comparative Example 3 is a conventional driving method, and the luminance maintenance rate of the fluorescent display tube was measured with the pulse width tp fixed at 250 μs and the repetition period T fixed at 15 msec.
In Example 3, the pulse width tp at the start of lighting was set to 250 μs and the repetition period T was set to 15 msec. However, as the lighting time passed, the condition that Du was 1/60 was maintained, and tp and T were shortened, respectively. . Table 3 shows the values of tp and T after the elapse of each time.
As shown in FIG. 22, compared with the comparative example 3 which greatly reduced the initial luminance, the example 3 was able to maintain the initial luminance.
In addition, after 48 hours from the start of lighting, the luminance maintenance rate was changed from 92% of Comparative Example 3 to 100%, and after 170 hours, the luminance maintenance rate was changed from 80% of Comparative Example 3 to 96%, after 530 hours. In Example 3, the luminance maintenance rate was improved from 69% to 96%, and from 1000% to 57% after 1000 hours.

Example 4 and Comparative Example 4
After applying a phosphor in which 10% by weight of In ₂ O ₃ was added to SrTiO ₃ : Pr (red) on the carbon anode of the fluorescent display tube, tube formation was performed in a known fluorescent display tube manufacturing process.
Using the obtained fluorescent display tube, the anode and grid electrode (ebc) was lit at 50 Vpp and Du was 1/60, and the luminance maintenance rate was measured. The results are shown in FIG.
Comparative Example 4 is a conventional driving method, and the luminance maintenance rate of the fluorescent display tube was measured with the pulse width tp fixed at 250 μs and the repetition period T fixed at 15 msec.
In Example 4, the pulse width tp at the start of lighting was set to 250 μs and the repetition period T was set to 15 msec. However, as the lighting time passed, the condition that Du was 1/60 was maintained, and tp and T were shortened, respectively. . Table 3 shows the values of tp and T after the elapse of each time.
As shown in FIG. 23, compared with the comparative example 4 which greatly reduced the initial brightness, the fall of the initial brightness was small in the example 4.
In addition, after 48 hours from the start of lighting, the luminance maintenance ratio is changed from 77% of Comparative Example 4 to 104%, and after 170 hours, the luminance maintenance ratio is changed from 52% of Comparative Example 4 to 83% after 530 hours. Then, the luminance maintenance rate of Example 4 was improved from 39% to 70% and from 32% to 63% after 1000 hours.

Example 5 and Comparative Example 5
After applying a phosphor in which 10% by weight of In ₂ O ₃ was added to ZnGa ₂ O ₄ : Mn (green) on the carbon anode of the fluorescent display tube, tube formation was performed in a known fluorescent display tube manufacturing process.
Using the obtained fluorescent display tube, the anode and grid electrode (ebc) was lit at 50 Vpp and Du was 1/60, and the luminance maintenance rate was measured. The results are shown in FIG.
Comparative Example 5 is a conventional driving method, and the luminance maintenance rate of the fluorescent display tube was measured with the pulse width tp fixed at 250 μs and the repetition period T fixed at 15 msec.
In Example 5, the pulse width tp at the start of lighting was set to 250 μs and the repetition period T was set to 15 msec. However, as the lighting time passed, Du was maintained at 1/60, and tp and T were shortened, respectively. . Table 3 shows the values of tp and T after the elapse of each time.
As shown in FIG. 24, Example 5 was able to maintain the initial luminance, as compared to Comparative Example 5 that greatly reduced the initial luminance.
Further, after 48 hours from the start of lighting, the luminance maintenance rate was changed from 88% of Comparative Example 5 to 96%, and after 170 hours, the luminance maintenance rate was changed from 85% of Comparative Example 5 to 102%, 1000 hours later. Then, the luminance maintenance rate of Example 5 was improved from 72% to 97%, respectively.

  Since the driving method of the present invention can reduce the power consumption and extend the life of the fluorescent display tube, it can be suitably used for a fluorescent display tube using a phosphor with remarkable luminance saturation.

DESCRIPTION OF SYMBOLS 1 Fluorescent display tube 2 Glass substrate 3 Wiring layer 4 Insulating layer 5 Anode electrode 6 Phosphor layer 7 Anode substrate 8 Grid 9 Cathode 10 Face glass 11 Spacer glass

Claims (7)

A fluorescent display tube driving method for displaying a phosphor layer formed on an anode electrode under low-energy electron beam excitation by dynamic driving,
The phosphor included in the phosphor layer is a phosphor whose luminance is improved when the pulse width is shortened under the same duty cycle in the dynamic drive, and a voltage is applied to the anode electrode, A phosphor whose time to decrease to a luminance value of 10% of the saturated luminance value after the voltage application is stopped after the luminance of the body is saturated is 200 μsec or more,
The method for driving a fluorescent display tube, wherein the dynamic driving is such that a pulse width and a repetition period of pulses are made variable as time elapses in a direction in which the initial luminance of the phosphor is maintained.   2. The method for driving a fluorescent display tube according to claim 1, wherein the pulse width and the pulse repetition period are made variable while maintaining the anode voltage, grid voltage, and duty cycle at the values at the start of driving. .   3. The method for driving a fluorescent display tube according to claim 1, wherein the phosphor is a phosphor having a localized emission center.   3. The method for driving a fluorescent display tube according to claim 1, wherein the phosphor is a phosphor having at least one emission center of a transition metal ion emission center and a rare earth ion emission center.   5. The method of driving a fluorescent display tube according to claim 4, wherein the emission center is Mn ion, Pr ion, Eu ion, or Tb ion. The phosphor is ZnS: Mn, ZnGa ₂ O ₄ : Mn, SrTiO ₃ : Pr, CaTiO ₃ : Pr, Gd ₂ O ₂ S: Eu, Y ₂ O ₂ S: Eu, ZnGa ₂ O ₄ , Gd ₂ O ₂ It is at least one phosphor selected from S: Tb, Y ₂ O ₃ : Eu, La ₂ O ₂ S: Eu, SnO ₂ : Eu, Zn ₂ SiO ₄ : Mn, and CaS: Mn. The method for driving a fluorescent display tube according to claim 5. A fluorescent display tube that emits light by projecting a low-energy electron beam onto a phosphor layer formed in a vacuum vessel,
The phosphor layer is ZnS: Mn, ZnGa ₂ O ₄ : Mn, SrTiO ₃ : Pr, CaTiO ₃ : Pr, Gd ₂ O ₂ S: Eu, Y ₂ O ₂ S: Eu, ZnGa ₂ O ₄ , Gd ₂ O ₂ S: Tb, Y ₂ O ₃ : Eu, La ₂ O ₂ S: Eu, SnO ₂ : Eu, Zn ₂ SiO ₄ : Mn, and at least one phosphor selected from CaS: Mn,
2. The fluorescent display tube according to claim 1, wherein the phosphor layer is lit and displayed by a dynamic driving method in which a pulse width and a pulse repetition period are shortened with the lapse of driving time while maintaining the same duty cycle.

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