JPH08283710A - Method for using phosphor - Google Patents

Abstract

PURPOSE: To provide a method for using a phosphor, whereby a sufficient luminance can be always assured, while the consumption of electricity can be reduced. CONSTITUTION: A perceptible tolerance level of the luminance of a phosphor is set. Immediately before the luminance of the phosphor lowers to the tolerance level as a result of long-term emission of light, the luminance is restored by allowing the phosphor to store light energy by irradiation with e.g. ultraviolet light for a short time. Desirably, this operation of light emission and light energy storage is repeated. As the result, the phosphor can always keep a luminance higher than the tolerance level by periodically interrupting the continuous light emission of the phosphor by short-time light energy storage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of using a luminous body which can always secure sufficient brightness while saving power.

[0002]

2. Description of the Related Art Conventionally, as a phosphorescent material, there is a zinc sulfide-based phosphorescent material (ZnS: Cu, Cl). However, as shown by a brightness curve b in FIG. 1, since the light emission time (lifetime) is extremely short, For example, it has been used only for a limited purpose such as being attached to the tip of a blinking cord of a fluorescent lamp.

However, in recent years, boron-based, alumina-based, and strontium-based phosphors have been developed as phosphors, and such phosphors emit light for 8 to 12 hours as shown by the brightness curve c in FIG. Since it has a long life, the use of phosphorescent materials is widespread, and it is becoming widely used in various fields such as road guidance lights, concrete tiles, backup of various signs at the time of power failure, clock dials, etc. There is.

[0004]

However, the above-mentioned boron-based, alumina-based, and strontium-based phosphors have sufficient brightness in the latter half of the light emission time as shown in FIG. When the brightness of the body is lower than the recognizable level (that is, the permissible visual recognition level) L, there is a problem in visibility, and the original function as the phosphor cannot be fulfilled.

It is an object of the present invention to provide a method of using a phosphor to solve the above problems.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a luminous allowance level is set for the brightness of a phosphor, and the phosphor is irradiated with ultraviolet rays or the like for a short time immediately before the brightness is lowered to the allowance level due to long-time light emission. The present invention relates to a method for using a phosphorescent material, characterized by recovering the brightness level of the phosphorescent material.

The present invention is also characterized in that, in the above-described method of using the phosphor, light emission and light accumulation are repeated.

Here, as the phosphor capable of emitting light for a long time, for example, an aluminate phosphor which is activated with a specific rare earth element (Eu, Pr, Nd, Dy) and is substituted with boron is used. It can be preferably used.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of using the phosphor according to the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 shows the case where the phosphor is used for a road guide light, the horizontal axis is the light emission time of the phosphor used for the road guide light, and the vertical axis is the brightness of the phosphor.

Here, as the phosphor, an aluminate phosphor activated with a rare earth element Eu and substituted with boron was used.

On the vertical axis, L is the permissible level of visual recognition, and not only in complete darkness but also in the degree of moonlight,
It refers to the brightness level at which the phosphor is visible.

The permissible visual recognition level L is determined by the illuminance and temperature of the installation environment. This is because when the temperature of the installation environment of the phosphor increases, the amount of light emitted increases, but the light emission time decreases.

Also in the present embodiment, at dusk, the brightness curve a of the phosphor is gradually reduced while drawing a gentle parabola with the elapse of the light emission time as in the case of the brightness curve c. When the level L is reached and left as it is, the brightness is lower than the visual recognition permissible level L, and the passerby or the driver of the vehicle cannot visually recognize the road guide light.

However, in the present embodiment, a timer or the like is used to control the ultraviolet irradiation lamp to be automatically turned on when the light emission time has elapsed for 2 hours and to be kept on for 5 to 10 minutes. .

Therefore, as is clear from the brightness curve a shown in FIG. 1, during this lighting time, the light storage level of the phosphor is rapidly increased and the brightness is rapidly restored to the initial state or the initial level. .

When the UV irradiation lamp is automatically turned off after 5 to 10 minutes, the brightness of the phosphor is gradually reduced again while drawing a gentle parabola with the passage of the light emission time, and further, for about 2 hours, the visible level is maintained. The light is emitted while maintaining the brightness of L or more.

As described above, when the luminous body continuously emits light after dusk, the luminous body is constantly kept at a luminance of the permissible visual recognition level L or more by providing the luminous time periodically for a short time. As a result, the safety of passersby and car drivers can be ensured throughout the night.

Also, the lighting time of the ultraviolet irradiation lamp required for storing light in the light storing body may be a short time (about 5 to 10 minutes) with each elapse of a long time (about 2 hours) of light emission. It is possible to save electricity.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to the method of using the phosphors described in the embodiments. For example, the phosphors are other kinds of phosphors. The body can also be used, and as a means for storing light in the phosphor, a lamp or a solar system capable of irradiating light rays other than the UV irradiation lamp can be used. The sensor may detect the level of brightness in the environment where the lamp is installed, and may be turned on when the value becomes equal to or lower than the set value.

[0021]

According to the present invention, the brightness of the phosphor is set to the permissible level of visual recognition, and just before the brightness is lowered to the permissible level of visual recognition due to the emission of light for a long time, the phosphor is irradiated with ultraviolet rays or the like for a short time to store the light. The brightness of the phosphor is restored, and the emission and the accumulation of light are repeated.

As described above, when the luminous body continuously emits light, by periodically providing the luminous time for a short period of time, the luminous body can always maintain the luminance of the visual recognition allowable level or more, For example, when it is used as a road guide light, the safety of passers-by and car drivers can be ensured.

Further, the lighting time of the ultraviolet irradiation lamp required for storing light in the light storing body may be a short time each time a long light emitting time elapses, so that a significant power saving can be achieved.

[Brief description of drawings]

FIG. 1 is a graph showing a brightness curve when a method of using a phosphor according to the present invention is applied to a road guide light.

[Explanation of symbols]

a Luminance curve of the phosphor when the method of use according to the present invention is used b Luminance curve of the conventional phosphor c The luminance curve of the phosphor when the method of use according to the present invention is not used

Claims (2)

[Claims] 1. A brightness permissible level is set for the brightness of the phosphor, and immediately before the brightness falls to the permissible level due to long-time light emission, the phosphor is irradiated with ultraviolet rays for a short time to allow the phosphor to accumulate light. A method of using a phosphor, which is characterized by recovering a brightness level. 2. The method of using the phosphor according to claim 1, wherein the light emission and the light accumulation are repeated.