JPH04322050A - Light emission device - Google Patents

Abstract

PURPOSE:To carry out emission of light in at least two colors in a simple structure by sealing at least neon and mercury, and at least two kinds of cathodes of different work function, and by carrying out emission of light by switching the cathodes. CONSTITUTION:(Ba, Sr, Ca)O of low work function is applied to a cathode 1, while Ba2CaWO6 and so on of high work function is applied to a cathode 2. A predetermined amount of neon, argon, and mercury are sealed in a discharge container 4. In this structure, when the cathodes 1 and 2 are changed over by a switch 10 so as to carry out discharging, only mercury of low excitation level is emitted in the discharging between an anode 3 and the cathode 1, and the color of the light is thus blue. In the discharging between the anode 3 and the cathode 2, in addition to mercury, neon of high excitation level is emitted, and the color of the light is thus red. The emissions of light of red and blue colors are thus carried out through one discharge tube.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device such as a variable color fluorescent lamp.

0002

[Prior Art] Three types of discharge tubes, each of which emits red, blue, and green light, are housed in a single outer tube, and are lit up sequentially at a certain period and time width, and the period and time width are set appropriately. Japanese Patent Laid-Open No. 2-28228 describes a light-emitting device that changes the overall color of the emitted light from red to blue by changing the color to blue.

0003

[Problems to be Solved by the Invention] In the above-mentioned light emitting device, three discharge tubes are built into one discharge tube. Therefore, the device itself becomes larger and its structure becomes more complicated.

[0004] In the present invention, the discharge tube itself remains one,
The object of the present invention is to provide a variable color discharge tube with a simple structure.

[0005]

[Means for Solving the Problems] The above-mentioned problems are solved by using a lamp characterized in that at least neon, argon, mercury, and at least two or more types of cathodes having different work functions are sealed.

[0006]

[Operation] A discharge tube is constructed in which two or more types of cathodes with small inter-electrode distances and different work functions are sealed with neon, argon, and mercury. As a result, since the distance between the electrodes is short, light emission is dominant near the electrodes. When discharging using an electrode with a low work function, the cathode fall voltage is low, and mercury with a low excited level emits light. Therefore, the color of the light becomes blue. When discharging using an electrode with a high work function, the cathode fall voltage is high, and in addition to mercury, which has a low excited level, neon, which has a high excited level, also emits light. Since neon's emitted light color is red, the color of the light is red. Therefore, by switching between an electrode with a low work function and an electrode with a high work function, two types of luminescent colors, blue and red, can be obtained with one discharge tube.

[0007]

Embodiment A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

A spherical glass tube with a diameter of 40 mm was used as the discharge tube. The cathode 1 was coated with (Ba, Sr, Ca)O. Ba2CaWO6 was applied to the cathode 2. Then, each cathode was sealed at a distance of 3 mm from the anode. A nickel rod with a diameter of 1 mm and a length of 7 mm was used as the anode. In FIG. 1, the cathodes 1 and 2 are shown vertically parallel to each other, but in reality, they are installed parallel to each other at regular intervals on the same plane.

[0009]Neon is 5 Torr, argon is 5 Torr
r. Several mg of mercury is sealed.

A mechanical switch 5 shown in FIG. 2 switches the discharge between the anode 3 and the cathode 1 and the discharge between the anode 3 and the cathode 2.

As a result of lighting the discharge tube with DC 300 mA, the cathode drop voltage in the discharge between the anode 3 and the cathode 1 is approximately 1.
It became 2V. Mercury with a low excited level emits light with energy given by a voltage of 4.89V or more, so mercury emits light, and neon with a high excited level needs to be given energy with a voltage of 16.8V or more. It does not emit light at a voltage of 12V. Because mercury emits light, the color of the light is blue. In the discharge between anode 3 and cathode 2,
The work function of Ba2CaWO6 is (Ba, Sr, Ca)O
Since the voltage drop was about 30 V, in addition to mercury, which has a low excited level, neon, which has a high excited level, also emitted light, and the color of the light turned red.

The light emitting device of the first embodiment was able to change the color of the emitted light to blue and red using a single discharge tube with a simple structure.

[0013] The light emitting device of the first embodiment cannot utilize light with a wavelength of 254 nm emitted by mercury. Since 80‰ or more of the light emitted by mercury has a wavelength of 254 nm, this is extremely inefficient. In the second embodiment, Sr10 (PO4) is used as a blue phosphor on the tube wall of the discharge vessel 4 shown in FIG.
6Cl2:Eu was applied. Sr10 as blue phosphor
By applying (PO4)6Cl2:Eu, it became possible to use light with a wavelength of 254 nm as visible light.

In the second embodiment, the switch 9 is a semiconductor switch to switch the discharge between the anode 3 and the cathode 1 and the discharge between the anode 3 and the cathode 2.

The time width of the discharge between the anode 3 and the cathode 1 and the discharge between the anode 3 and the cathode 2, and the time width of the discharge between the anode 3 and the cathode 1 and the time width of the discharge between the anode 3 and the cathode 2 at a certain lighting time. By appropriately changing the number of discharges, the color of the emitted light could be changed continuously from red to blue.

In the light emitting device of the second embodiment, the light of 254 nm, which could not be used in the light emitting device of the first embodiment, can be utilized by applying a phosphor. Therefore, the light emitting device of the second embodiment is a very efficient light emitting device.

[0017]

According to the present invention, it is possible to provide a light emitting device that can emit red and blue light colors using a single discharge tube.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a discharge tube according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a light emitting device according to a first embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...Cathode with low cathode drop voltage, 2...Cathode with high cathode drop voltage, 3...Anode, 4...Discharge vessel, 10...Switch.

Claims (1)

[Claims] Claim 1: At least neon and mercury;
A light-emitting device using a lamp characterized by encapsulating more than one type of cathode.