JPH0340361A - Low pressure rare gas discharging fluorescent lamp with hot cathode - Google Patents

Abstract

PURPOSE:To increase the brightness without involvement of abrupt rise of the tube voltage and eliminate risk of brightness saturation due to the increase in the tube current by using at least Kr as the light emission gas, and setting its partial voltage below a specific value. CONSTITUTION:A pair of electrodes 2a, 2b are installed in a glass bulb 1, wherein a filament coil coated with electron emitting substance is used. A fluorescent substance layer 3 is formed over the inner surface of this bulb 1. Within this bulb 1, a light emission gas 4 of Kr is encapsulated at 5Torr or less. If the tube current is increased, therefore, the brightness is increased due to combination of the light emission from the fluorescent substance layer with the increase of the atomic light emission in the visible range of Kr. Even though further increase of the tube current has resulted in saturated condition of the light emission from the layer 3, the atomic light emission will increase in the visible range of Kr to accomplish increase of the brightness.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to office automation such as facsimiles and copying machines (
OA) This paper relates to improving the brightness of heat shaded low pressure rare gas discharge fluorescent lamps used in related equipment.

[Conventional technology]

In recent years, fluorescent lamps that utilize light emission from rare gas discharge have been adopted as light sources for office automation equipment.

For example, high-intensity glow lamps filled with a gas containing xenon (Xe) as a main component have been announced. This is a cold bucket type gas discharge fluorescent lamp that excites the phosphor with ultraviolet light emitted by the glow discharge of Xe gas inside the tube to emit light. This lamp has the advantage that stable light output can be obtained over a wide temperature range without using mercury, and that the color of the light source can be changed depending on the application by changing the phosphor.

However, this cold cathode model gas discharge fluorescent lamp required a high voltage for lighting, which caused some problems in handling. Therefore, the inventors have been studying hot cathode type gas discharge fluorescent lamps that have a low lighting voltage and have fewer problems associated with high voltages. As a result, the heat shade type gas discharge 7TC fluorescent lamp,
It was confirmed that the optical output qualitatively had the characteristics shown in FIG. It is lit with a bi-hot cathode tube diameter of 15.5 mm, an AC sine wave of 30 kl+, the tube current is constant at 100 mA, and the filled gas is 100% Xe. As is clear from the figure, the brightness is at its lowest when the Xe pressure is around 5 Torr, and in order to improve the brightness, the pressure of the filled gas can be lowered or conversely increased. However, when the pressure of the filled gas is lowered, the tube voltage does not rise so suddenly, but when the pressure of the filled gas is increased, the tube voltage also rises rapidly. That is, the tendency of the electric characteristics of the lamp differs greatly at a gas pressure of 5 Tor rf 1 degree. The inventors used Xe as a luminescent gas to investigate the Xe-containing fraud.
The remaining 90% is He.

When I tried changing it to Ne, Ar, and Kr, it turned out to be He and Ne at the same filled gas pressure of about 1 Torr.

The brightness decreased in the order of Ar and Kr. Further, when a mixed gas of two types of Xe and Ne is used and the amount of Xe mixed is increased, the brightness decreases at the same filled gas pressure of about ITorr. The above is about 5 Torr
This is because this is an effective region that meets the purpose of reducing tube voltage.
In the gas pressure range higher than that, strange development occurred, but
Here, I will omit [[1] because it is off the mark. Now, when a mixed gas is used, the filled gases J and 'E that give the lowest brightness are on the high pressure side, that is, 5 Torr, as the Xs mixture ratio decreases.
Moving on to higher pressures, approximately FE for Xs was 5 Torr 1 f 1 degree.

The above is a qualitative explanation of the Xe discharge fluorescent lamp, but for the purpose of high brightness and low voltage, the inventors
We have been considering lamps with o r r or less.

[Problem to be solved by the invention]

Now, let us assume that a region where the Xe partial pressure is 5 Torr or less will be called a low pressure region, and a region higher than that will be called an intermediate pressure region. The inventors used low-pressure Xe
Although we have been studying discharge, it has become clear that there are major problems in the low-voltage region when it comes to increasing brightness. For example, in order to simplify the problem and explain it qualitatively, let us now consider the case where a lamp is filled with 100% Xe gas. In reality, however, the brightness is higher when mixed gases are used. Then, for lamps in the medium-pressure range, the brightness increases as the tube current increases, but for lamps in the low-pressure range, the increase in tube current conversely causes a decrease in brightness after a certain tube current value. As shown in Figure 3, the tube current is about 70
It was found that there is a problem in that the brightness reaches its maximum value at mA, and even if the tube current is changed, no higher brightness can be achieved. This is a problem that did not exist with lamps in the medium pressure range.

This invention has been made to solve the above problems. That is, the objective is to obtain a hot cathode type low-pressure rare gas discharge fluorescent lamp that does not involve a sudden increase in tube voltage when increasing brightness as in the medium pressure region, and also does not saturate brightness due to increased tube current as described above. shall be.

[Means to solve the problem]

For this reason, the hot cathode type low pressure rare gas discharge fluorescent lamp according to the present invention is provided with a pair of main rods including electrodes that operate as hot cathodes at least in a stable discharge state in the glass bulb, and a phosphor layer is formed on the inner surface of the glass bulb. A luminescent gas is further sealed inside, and the luminescent gas has a partial pressure of 5 Torr or less, which causes the phosphor layer to emit light with radiation emitted by the luminescent gas during discharge, and the luminescent gas is at least krypton. The above objective is achieved by a configuration characterized by (r).

[Effect]

Xe mainly emits vacuum ultraviolet light of 147 nanometers (nm), which excites the phosphor and causes it to emit light.

However, when observing the lamp in detail, it can be inferred that the following phenomenon occurs. In other words, in the low pressure region, as the tube current increases, 147 nm radiation increases.
Above a certain tube current value, this 147 nm radiation does not increase but becomes saturated, and the energy disappears in the infrared radiation of Xe.
? Therefore, the brightness does not increase. In the medium pressure region, there is no saturation or the tube current value is very high, so an increase in the tube 7tt flow was accompanied by an increase in wavelength of 147 nm, resulting in an increase in brightness.

If the luminescent gas is nir, each time the phosphor is excited with Kr124nm vacuum ultraviolet rays, in this case as well, if the lamp is made in the low pressure region where the tube voltage is low, the 124nm vacuum ultraviolet radiation due to the tube current will be saturated. However, Kr has a lot of atomic emission in the visible range, and even if the vacuum ultraviolet radiation at 24 nm is saturated by increasing the tube current, these atomic emissions will not be saturated. That is, unlike Xs, which has a brightness saturation phenomenon due to an increase in current, the brightness does not saturate in K'.

That is, in the hot cathode type low pressure rare gas discharge fluorescent lamp of the present invention, an increase in the tube current causes an increase in the luminescence of the phosphor layer.
The luminance increases due to the increase in atomic luminescence in the visible range, and even if the tube current increases and the luminescence of the phosphor layer approaches saturation, the atomic luminescence in the visible range increases and the luminance increases. do.

〔Example〕

Hereinafter, the hot cathode type low pressure rare gas discharge fluorescent lamp of the present invention will be explained with reference to Examples.

FIG. 1 is a partial cross-sectional outline view of a hot cathode low pressure rare gas fluorescent lamp according to an embodiment of the present invention.

In the figure, 1 is a glass bulb with a tube diameter of 8fflII+. 2a and 2b inside are a pair of electrodes,
It uses a triple filament coil coated with an electron-emitting material and operates as a hot cathode, at least under stable discharge conditions. Note that the electrode tube distance was 280 mm.

A phosphor layer 3 is formed on the inner surface of the glass bulb l. The phosphor used is terbium-activated yttrium silicate represented by Y2 S+ Os /Tb. In addition, the inside of the glass bulb l contains 1100% luminescent gas 4.
is pressure 0. Enclosed in ITorr.

Next, we will discuss the performance of this example, which has the same dimensions and structure as this example, and the luminescent gas is 100% Xe, and the pressure is 0.
This will be explained in comparison with the one enclosed in ITorr.

When the tube currents of these two types of fluorescent lamps were varied and the brightness was measured at the center of the lamp using a Minolta brightness meter, the results were as shown in Figure 3.

Brightness is Xe 100%%, 0. The values are expressed as relative values, with the value of the tube current of 70 mA of the ITorr lamp set as 100. Tube current 8
XelOO% up to about 0mA.

Although the brightness of 0.ITorr is slightly higher, the brightness of Xe decreases at higher tube current values, whereas the brightness of Kr
100,0. ITorr lamps do not tend to saturate in brightness. When we investigated this spectral distribution, we found that it was as shown in Figure 4.

In Figure 4, the solid line is tube current 30mA, the dotted line is 70mA, -
When one point 3nlLil is 110mA (7), it is monotial.

In the figure, the shaded area is the light emitted by the phosphor, and the letter ``r'' is ``K''.
This is the light emission of r. As is clear from the figure, the luminescence of the phosphor is saturated at a tube TL flow of about 70 mA, and does not increase much even at 110 mA, whereas the atomic luminescence of Kr is 557 nm, 585 nm, 432 nm, 447 nm.
In the case of m, etc., the luminescence increases as the tube current increases.

In other words, the reason why the brightness of Xe becomes saturated is because the vacuum ultraviolet rays of Xe that excite the phosphor become saturated.MLiI!
It seems that the increase in lamp power will cause Xe to emit infrared light. This seems to be the same for Nir, but
The difference is that Kr has many spectra in the visible range, and these emissions increase as the lamp power increases. Therefore, even if the light output of the phosphor is saturated, the Kr lamp is able to maintain the irradiance even when the light output of the phosphor is saturated. Since the X-son emission increases in the emission viewing area, it can be assumed that the effect shown in FIG. 3 is exhibited.

The above was shown in an example using KrlOO%, but the same effect was obtained even if He, Ne, or Ar was added as a buffer gas to Kr.

Although the shape of the glass bulb is a straight tube in this embodiment, it is not limited to this, and may be annular, U-shaped, or other shapes.

For reference, the spectral distribution of a Riot, 30 Torr lamp is shown in FIG. As is clear from the figure, when the tube current was increased, the luminescence of the phosphor itself increased, giving rise to characteristics different from those in the low-pressure region.

〔Effect of the invention〕

As explained above, according to the present invention, the luminescent gas of the hot cathode low pressure rare gas discharge fluorescent lamp is at least krypton, and its partial pressure is 5 Torr or less, so that the tube current can be reduced. When increased, the luminescence of the phosphor layer and Kr
The brightness increases with the addition of increased atomic emission in the visible range.

Furthermore, by increasing the tube current, even if the luminescence of the phosphor layer reaches a saturated state, the atomic luminescence of Kr in the visible range increases and the brightness can be increased. Moreover, there is no sudden increase in tube voltage due to increase in brightness. Since the lighting voltage is low, it is possible to provide a hot cathode type low pressure rare gas discharge fluorescent lamp which is free from handling problems compared to high pressure discharge lamps.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional outline view of a thermal 113M1 type low-pressure rare gas discharge fluorescent lamp, which is an embodiment of the present invention, and FIG.
Figure 3 is a characteristic diagram of a filled gas 100% Xe discharge fluorescent lamp. Figure 4 is a characteristic comparison diagram of a low-pressure rare gas discharge fluorescent lamp. Figure 4 is a spectral distribution diagram of the Kr100°0, ITorr discharge fluorescent lamp of the present invention. Figure 5 shows Kr100%, 30Torr
It is an extra-spectral IiT diagram of a discharge fluorescent lamp. 1 is a glass bulb, 2a and 2b are electrodes, 3 is a phosphor layer,
4 is a luminescent gas.

Claims (1)

[Claims] A pair of electrodes including an electrode that operates as a hot cathode at least in a stable discharge state is provided in the glass bulb, a phosphor layer is formed on the inner surface of the glass bulb, and a luminescent gas is sealed inside, and the luminescent gas is released by discharge. The partial pressure of the enclosed luminescent gas which causes the phosphor layer to emit light with the emitted radiation is 5 Torr (Tor).
r) or less, and the luminescent gas is at least krypton (Kr).