JPH0448547A - light emitting device - Google Patents

Abstract

PURPOSE:To obtain the visible light during the period when no power is applied to a lamp by providing a discharge lamp structure having phosphors excited by the radiation light from an afterglow generated by an intermittent discharge and generating the visible light. CONSTITUTION:During the period when voltage is applied to a lamp 10, active plasma is generated and the energy state of electrons becomes high, and the emission of resonance lines 254nm of mercury is dominant like a normal fluorescent lamp. The resonance lines 254 nm of mercury illuminate phosphors of the first group, and the daytime white light is obtained during this period. During the period when no voltage is applied to the lamp 10, an afterglow is generated, the energy of electrons becomes very low, the resonance lines 254nm become very weak, however spectrum lines of mercury atoms 365-nm due to the re-bonding of mercury ions are strongly illuminated. The spectrum lines of mercury atoms 365nm illuminate phosphors of the second group, thus red luminescence is obtained during this period.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a discharge lamp, and particularly to a discharge lamp for illumination such as a fluorescent lamp.

[Conventional technology]

A low-pressure discharge device with variable emission color that performs intermittent discharge to emit at least two types of ultraviolet rays, and converts these ultraviolet rays into visible light using multiple types of phosphors with different excitation sensitivities and different emission colors, has been approved by a special 2-2266. The method for varying the color of emitted light in this low-pressure discharge device was to change the rising slope of the voltage waveform applied to the discharge lamp.

[Problem to be solved by the invention]

In the conventional low-pressure discharge lamp device described above, only the light emitted from the plasma generated in the lamp when voltage is applied to the lamp, so-called active plasma, is utilized. In addition to the emitted light, the light emitted from the so-called afterglow, which is the plasma that exists inside the lamp when voltage is not applied to the lamp, is used to create highly efficient light-emitting devices and variable-color light-emitting devices. It is to provide.

[Means to solve the problem]

The above object is a light emitting device characterized by having at least a lighting circuit for performing intermittent discharge, and a discharge lamp provided with a phosphor that is excited and emits light by at least emitted light from afterglow generated by the intermittent discharge. This is achieved by using a method.

[Effect]

At least, a discharge lamp structure that performs intermittent discharge in a lighting circuit for performing intermittent discharge and is provided with a phosphor that is excited by radiation from the afterglow generated by the intermittent discharge and generates visible light can be used in the lamp. Since visible light can be obtained even during periods when power is not injected, a highly efficient light emitting device can be obtained.

In active plasma and afterglow, the energy distribution of electrons is naturally different, and therefore the spectral energy distribution of synchrotron radiation is also different. That is, the effective wavelengths of ultraviolet rays in active plasma and afterglow are relatively different. Therefore, one or more types of phosphors with different excitation sensitivities and different emission colors for the two effective types of ultraviolet rays described above are provided, and the ratio between the active plasma generation period and the afterglow period is changed. Then, a light-emitting device with variable light color can be obtained.

Generally, the radiation intensity of ultraviolet rays emitted from afterglow is small compared to the radiation intensity of ultraviolet rays from active plasma, so the phosphor that emits light with the radiation from afterglow has a substantial effect on the radiation from afterglow. When the excitation efficiency is greater than the effective excitation efficiency for emitted light from the active plasma, the advantage is that the range of variable colors becomes larger.

In general, the energy of electrons in active plasma is greater than the energy of electrons in afterglow.
Therefore, the effective wavelength of the ultraviolet light emitted from the active plasma is shorter than the effective wavelength of the ultraviolet light emitted from the afterglow. It is also excited by synchrotron radiation from afterglow.

The luminescent phosphor often emits even with effectively short-wavelength ultraviolet rays emitted from the active plasma. When a second phosphor that is excited by light is provided, the effectively short-wavelength ultraviolet rays emitted from the active plasma are absorbed by the second phosphor, and the light emitted from the afterglow excites and emits light. The substantially long-wavelength ultraviolet rays emitted from the afterglow, which do not reach the phosphor, transmits through the second phosphor, causing the phosphor excited by the emitted light from the afterglow to emit light. As described above, when a second phosphor that is excited by the light emitted from the active plasma is provided on top of the phosphor that is excited and emits light by the emitted light from the afterglow, the emitted light from the afterglow Since the excited phosphor emits light only by the light emitted from the afterglow, the advantage is that the range of variable colors is widened.

When at least mercury is used as the discharge gas, a highly efficient light emitting device can be obtained.

The main component of the discharge gas is a rare gas, and the atomic weight of the rare gas is M.
When the pressure of the rare gas expressed in Torr is 807M
If it is less than 4000/2, the recombination during afterglow will be reduced and the light emission will be reduced in afterglow.
If it exceeds M, there will be a drawback that it will be difficult to start the discharge. That is, when the main component of the discharge gas is a rare gas and the atomic weight of the rare gas is M, the above effect is even more achieved when the pressure of the rare gas expressed in Torr is in the range of 80/M to 4000/M. Ru.

When the inner diameter of the discharge lamp is less than 8 m, recombination during afterglow is reduced, resulting in less light emission during afterglow, and when the inner diameter exceeds 251 Il, the discharge becomes unstable.

That is, the above effects are even more achieved when the inner diameter of the discharge lamp is 8 mm or more and 25 mm or less.

When the vapor pressure of mercury in the discharge lamp is less than 0.0.001 Torr and exceeds 6 Torr while operating at the rated power, there is a drawback that the efficiency is low.

That is, a highly efficient light-emitting device can be obtained by controlling the vapor pressure of mercury in the discharge lamp during operation at rated power to 0.001 Torr or more and 6 Torr or less.

[Example] Fig. 1 shows a first example of the present invention, with a pipe diameter of 18 m,
Hot cathodes 1 and 2 are sealed at both ends of a straight glass discharge vessel 4 having a length of 40 cm. The discharge gas is 5 Torr.
r of argon and mercury, the vapor pressure of mercury during rated operation is 0.09 orr.

A phosphor 3 was applied to the inner surface of the discharge vessel 4. The phosphor 3 is a rare earth phosphor that is mainly excited by the 254 nm resonance line of mercury atoms, and includes Y2O):Eu that emits red light, (La,Ce)PO4:Tb that emits green light, and (La,Ce)PO4:Tb that emits blue light. It emits light (Sr, Ca, B a .

a first group of phosphors which is a mixture of Mg), , (PO4), CQ, :Eu, and a further 365 nm
Y, AQ, O, □ which is excited by
:Ce and 3,5Mg0, which mainly emits deep red light.
A second group of phosphors consisting of 0.5MgF, .GeO, :Mn was applied.

FIG. 2 shows a block diagram of a lighting circuit for performing intermittent discharge. A commercial power source 11 is converted into direct current by a rectifier circuit 12, and is supplied to a full-bridge inverter 14 through a step-down inverter 13.

The full-bridge inverter 14 is driven by the control circuit 16, and as shown in FIG. 3, generates an intermittent alternating current voltage during a voltage application time T1 and a voltage non-application time T2. In this example, T1 is 20μs and T2 is 200μs.
It is s. During voltage application time T1, a lamp current of 2 amperes was supplied.

15 is a preheating circuit for preheating the hot cathodes 1 and 2, and is controlled by a control circuit 16.

17 is a means for detecting lamp current.

By feeding back the detected value at 17 to the step-down inverter 13 through the control circuit 16, the value at 17°16.13 serves as a stabilization record for the discharge lamp.

When the lamp 10 is lit using an intermittent alternating current voltage as shown in FIG. 3 generated by a lighting circuit as shown in FIG. 2, the following light emission is obtained. first.

During the period when voltage is applied to the lamp 10, active plasma is generated and the energy state of electrons is high.
Emission at 54 nm is dominant. Mercury resonance line 254
nm makes the first group of phosphors glow, thus daylight white light is obtained during this period.

On the other hand, during the period when no voltage is applied to the lamp 10, afterglow occurs, and therefore the electron energy is very low, and the 254 nm becomes very weak.
Spectral line 36 of mercury atoms due to recombination of mercury ions
5 nm emits strong light. Mercury atom spectral line 365
nm causes the second group of phosphors to emit light, thus red light emission is obtained during this period.

The illumination light emitted from the above light emitting device is the average of the light emitted during a period when a voltage is applied to the lamp and the light emitted during a period when no voltage is applied.

As described above, in the light emitting device of the present invention, high efficiency is achieved because the light emitted during the period when no voltage is applied to the lamp is also utilized.

Furthermore, the period Tl during which the voltage is applied, ! Period T2 during which no pressure is applied. By controlling the magnitude of the lamp current during the period when the voltage is applied, either individually or simultaneously through the +'# control circuit 16, a light emitting device capable of changing colors can be obtained.

In the above embodiments, argon gas was used as the rare gas, but it is obvious that xenon, neon, and helium can also be used.

In another embodiment of the present invention, the trivalent cerium ion-activated aluminate phosphor used in the first embodiment, the tetravalent manganese ion-activated germanate phosphor, (Sr, Ca , B a .

Mg)x. (PO4), C: flz: Eu A phosphor coated with a substance that does not transmit 5254 nm but transmits 365 nm, such as MgO, is used. In the phosphor of this example, 254 nm, which is the emitted light from the active plasma,
is absorbed by MgO, so that the substantial excitation efficiency for the 365 nm emitted light from the afterglow is much larger than the substantial excitation efficiency for the emitted light from the active plasma. Therefore,
The advantage arises that the range of variable colors is widened.

FIG. 4 shows a voltage waveform for intermittent discharge according to another embodiment of the present invention, in which high-frequency power is intermittently supplied. T1.
By appropriately selecting T2, the same effect as in FIG. 3 can be obtained.

FIG. 5 shows another embodiment of the present invention, in which a phosphor 3Sr, (PO4), .CaCQ emits blue light when excited by afterglow radiation at 254 nm and 365 nm.

3 as a second phosphor 20 excited by the resonance line 254 nm of mercury atoms emitted from the active plasma, 03: Eu and MgA Q 110ts: Ce
, Tb. The period during which voltage is applied to the lamp is 254nm.
During the afterglow period, when the blue light does not reach the wavelength of 365 nm, the main emitted light is 3 S.
ra (p 04) 2 ・CaCQ 23 is excited and only blue light is emitted. Above the phosphor, which is excited and emitted by the emitted light from the afterglow, is emitted from the active plasma. A two-layer phosphor system in which a second phosphor excited by the second phosphor is provided has the advantage of widening the range of variable colors.

〔Effect of the invention〕

According to the present invention, a light emitting device with a high efficiency light emitting device 5 whose emission color is variable can be obtained.

[Brief explanation of the drawing]

1 and 5 are cross-sectional views of a discharge lamp according to an embodiment of the present invention, FIG. 2 is a block diagram of a lighting circuit according to an embodiment of the present invention, and FIGS. 3 and 4 are a lighting circuit of the present invention. This is the output voltage waveform of Explanation of symbols 1.2...electrode, 3,20...phosphor, 1o...
Discharge lamp, 13...Step-down inverter, 14 mountain bulburi 舅 1ρ 1 sentence 1 begging rashif 0 rod ■ diagram group

Claims (1)

[Claims] 1. A discharge lamp equipped with at least a lighting circuit for performing intermittent discharge and a phosphor that is excited and emits light by at least emitted light from afterglow generated by the intermittent discharge. A light emitting device. 2. The light emission according to claim 1, wherein the substantial excitation efficiency for emitted light from afterglow of the phosphor is greater than the substantial excitation efficiency for emitted light from active plasma. Device. 3. Claim 1, characterized in that a second phosphor excited by light emitted from the active plasma is provided on the phosphor excited and emitted by the light emitted from the afterglow. The light emitting device described in Section 1. 4. The light emitting device according to any one of claims 1 to 3, characterized in that at least mercury is used as a discharge gas of the discharge lamp. 5. When the main component of the discharge gas is a rare gas and the atomic weight of the rare gas is M, the pressure of the rare gas expressed in Torr is 80/
The light-emitting device according to any one of claims 1 to 4, wherein the light emitting device is not less than M and not more than 4000/M. 6. The light emitting device according to any one of claims 1 to 5, wherein the discharge lamp has an inner diameter of 8 mm or more and 25 mm or less. 7. According to any one of claims 4 to 6, wherein the vapor pressure of mercury in the discharge lamp during operation at rated power is 0.001 Torr or more and 6 Torr or less. The light emitting device described. 8. The lighting circuit for performing intermittent discharge has means for varying at least one or more conditions selected from the intermittent discharge time, the discharge rest time, and the magnitude of the discharge current of the intermittent discharge. A light emitting device according to any one of claims 1 to 7, characterized in that: