JPS5923587B2 - phosphor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phosphor that is excited by slow electrons and emits orange light.

2. Description of the Related Art Fluorescent display devices have traditionally been widely used in the numerical display portions of electronic desktop calculators and digital clocks. This fluorescent display device allows electrons emitted from a filament-shaped cathode to collide with a plurality of anodes on which a phosphor layer is applied and which is selectively given an anode potential. It has a structure that displays characters, figures, etc. Incidentally, in the anode of this fluorescent display device, the phosphor layer is mostly made of a ZnO:Zn system so that sufficient brightness can be obtained by low anode voltage, that is, by excitation of slow electrons. It is composed of a phosphor.
This ZnO:Zn-based phosphor has a luminescence threshold voltage,
The so-called dead voltage is extremely low at 1 to 2V.
In addition, in general, sufficient luminance can be obtained with an anode voltage of about 10 to 20 V to obtain a display, and greenish luminescence with extremely high relative luminous efficiency can be obtained, so this ZnO:
A fluorescent display device using a Zn-based phosphor has the advantage of being able to be driven at a low voltage, consuming little power, and providing an extremely easy-to-read display. Fluorescent display devices with such various features can be used not only in numerical display units of various electronic devices as mentioned above, but also in display units of various measuring instruments, level meters of audio equipment, and speed meters of vehicles. Its application fields have been greatly expanded, such as analog display parts such as tachometers and tachometers.

As the field of application of fluorescent display devices has expanded in this way, there has been a demand for a fluorescent display device that can display in a luminescent color other than green, depending on the field of application. For example, in a display device that displays danger,
If characters, drawings, etc. are displayed in red-ish colors, the warning effect will be improved, and yellow to orange colors are desirable for display in dark places with relatively little ambient light.

Furthermore, if the luminescent color of analog display devices such as the level meters mentioned above changes when the displayed value exceeds a set level, it is expected that the alarm effect will be improved, and it will also be possible to detect amounts exceeding the set level. Display effects such as immediate readability are expected. Various attempts have been made to develop phosphors that emit light in colors other than green when excited by slow electrons.
Zn, Cd) S: Cu, and Al have been subjected to appropriate treatments to produce phosphors that emit light in yellow to orange colors when excited by slow electrons.

Gate 3 - However, this (Zn.Cd)S:Cu. Al phosphor contains Cd, which is harmful to the human body, which poses problems in terms of pollution, and it is troublesome to handle during manufacturing and post-processing, as well as being difficult to excite slow electrons. Therefore, there is a problem that the brightness obtained is still not sufficient.

Therefore, the present invention was made in view of the above-mentioned circumstances, and aims to obtain a phosphor that emits orange light due to the excitation of slow electrons. ZnS:Mn. In the Cl-based phosphor, I
It was discovered that the dead voltage could be significantly lowered by adding an appropriate amount of conductive or semiconductive metal oxides such as n2O3 or SnO2, and based on this result, it was possible to excite slow electrons. A phosphor that emits light in the orange range was obtained by this method.

That is, the present invention provides ZnS:Mn, . 1n20, S as a conductive or semiconductive metal oxide in the Cl phosphor.
By adding an appropriate amount of nO2 to lower the specific resistance of the ZnS:Mn,Cl phosphor and improve its conductivity, the dead voltage can be lowered to about 5 to 10 V. The purpose is to obtain a phosphor that emits orange light when excited. below,
An embodiment of the phosphor according to the present invention will be described.

The phosphor of the present invention can be obtained, for example, through the following manufacturing process.

First, ZnS, which is one component of the phosphor of the present invention:
Mn. To obtain a Cl phosphor, a predetermined amount of unfired Zn
Weigh the S powder.

Next, an aqueous solution containing MnCl2 corresponding to an amount of Mn of about 0.1 to 5%, preferably about 1%, and about 0.2% NaCl is formed, and ZnS powder is mixed into this aqueous solution. After stirring thoroughly, the moisture is evaporated, and the mixture is further dried by heating to about 70° C. in air, for example.

Furthermore, the above-obtained (ZnS+MnCl2+Na
Cl) powder 1 is filled in a crucible 2 as shown in FIG. 900 to 1000 in this N2 air flow.
By heating and baking at a temperature of about 1 to 3 hours, ZnS:Mn. Obtain a Cl phosphor.

The thus obtained ZnS:Mn,. A metal oxide, that is, a metal oxide having conductivity or semiconductivity, is added to the Cl phosphor to improve its conductivity.

This metal oxide is a substance that is stable in the phosphor and does not inhibit the luminescence of the phosphor, such as N2.
Use O3. Therefore, the 1n203 was converted into ZnS:M
n. Approximately 15% by weight of the Cl phosphor is weighed, and both are placed in, for example, an agate mortar and mixed well to obtain the (ZnS:Mn.Cl+In2O3) phosphor of the present invention. Next, the characteristics of the phosphor obtained as described above will be described.

First, in order to investigate the characteristics of the above-mentioned phosphor, the inventor manufactured a phosphorescent display device whose schematic configuration is shown in FIG. 2.

That is, the anode 13 on which the phosphor layer 12 of (ZnS:Mn.Cl+In2O3) described above is deposited is disposed in a vacuum envelope 11 having a transparent display window.
A filament-shaped cathode 14 that emits electrons by heating with electricity is provided facing the electrode 3, and a mesh-shaped control electrode 15 that accelerates and controls the electrons is provided between the anode 13 and the cathode 14. It is a composition. Furthermore, external terminals 16 led out of the vacuum envelope 11 from each electrode in a vacuum-tight manner apply a heating voltage Ef to the cathode 14, a control voltage Ec to the control electrode 15, and further apply a control voltage Ec to the anode 13. Anode voltage Eb is applied to.

Therefore, in the device shown in FIG. 2, the anode voltage E
FIG. 3 shows the voltage-brightness characteristics obtained by measuring the luminance of light emitted from the anode 13 with respect to b.

The curve indicated by the solid line A in FIG. The (ZnS:Mn, C1+In2O3) phosphor has a dead voltage of about 5V, and a brightness of about 100CFt-L with an anode voltage Eb of 30V.
This makes it possible to obtain sufficient brightness for display using low-speed electrons.

Further, the emission spectrum characteristics of the above-mentioned phosphor were as shown in FIG. 4, and orange light emission having a peak value around 582 nm was obtained.

By the way, in the above-mentioned example, an example is shown in which approximately 15% by weight of In2O3 is added to the ZnS:Mn,Cl phosphor, but if the amount of In2O3 added is small, the broken line in FIG. When the dead voltage becomes high and increases as shown by the curve shown in Figure 3, the dead voltage decreases or the luminous efficiency also decreases at the same time, as shown by the dashed line in Figure 3. As a phosphor for an optical display device, the amount of 1n203 added is 5 to 50
It can be said that a range of approximately % is appropriate.

Moreover, ZnS:Mn. The conductive or semiconductive metal oxide to be added to the CI phosphor is not limited to the above-mentioned In2O3, but also substances that are stable in the phosphor and do not inhibit the light emission of the phosphor. , for example SnO
2 can also be used.

Furthermore, it goes without saying that the phosphor according to the present invention can be obtained not only by the above-mentioned manufacturing process, but also by other manufacturing processes. In addition, the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications without changing the gist thereof.

As described above, the phosphor according to the present invention has a high dead voltage of several hundreds of volts, and conventionally the phosphor of the present invention is a ZnS:Mn. An appropriate amount of a conductive or semiconductive metal oxide such as In2O3 or SnO2 is added to a Cl-based phosphor to lower the specific resistance of the phosphor. Therefore, the dead voltage is significantly lowered to 10 V or less, and it becomes possible to obtain orange light emission with sufficient brightness to obtain a display even with low-speed electrons. If a fluorescent display device is constructed using this material, it is expected that the field of application as a display device will be greatly expanded, and that the display effect will also be improved.

Furthermore, since the phosphor according to the present invention does not contain substances that cause pollution problems such as Cd, the phosphor manufacturing process can be easily controlled, and it can be manufactured at low cost. It has the following.

Further, ZnS, which is the base material of the phosphor according to the present invention:
Mn. Among the Cl phosphors, Mn as an activator is a transition element and emits light when excited by a slow electron beam due to intraatomic transition.

Further, Cl acts as a co-activator and a donor impurity within the matrix, making the N-type semiconductor characteristics of ZnS stronger. Therefore, in the present invention, the amount of metal oxide mixed into the matrix to improve its conductivity may be small.

Here, the mixed metal oxide improves the conductivity of the phosphor, but does not emit light by itself. Therefore, when the amount of the metal oxide mixed increases, the light emitting surface area of the phosphor increases. The light emission efficiency decreases or uneven light emission occurs, resulting in poor light emission efficiency.

However, in the present invention, due to the characteristics of the base material, only a small amount of metal oxide is required, and the luminous efficiency is extremely good.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of manufacturing a phosphor according to the present invention;
FIG. 2 is a diagram showing a fluorescent display device manufactured to obtain the characteristics of the phosphor according to the present invention, and FIGS. 3 and 4 are
FIG. 3 is a diagram showing the characteristics of a phosphor according to the invention.

Claims (1)

[Claims] 1 ZnS: A phosphor that emits orange light when excited by slow electrons, which is made by mixing Mn and Cl phosphors with a metal oxide of at least one of In_2O_3 and SnO_2.