JPH0378735B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device that displays information by emitting visible light.

In the field of displays using gaseous emission media, such as neon tubes, seven-segment character displays, numeric display tubes and plasma displays, the standard gas mixture usually consists mainly of neon, often with xenon or Small amounts of other noble gases such as argon are mixed in. These mixtures emit electromagnetic radiation in the orange and red regions of the optical spectrum towards the low frequency end of the average eye response. Field workers have particularly desired gases or gaseous mixtures that emit green or blue electromagnetic radiation, regions of the spectrum to which dark-adapted eyes are more sensitive. The most effective mixture known to date is GFWatson's paper
This was published in the Journal of Physics E8.981 (1975). One improvement is to use a gaseous mixture that emits electromagnetic radiation in the ultraviolet range, and the ultraviolet radiation is converted into visible light by a phosphor coated on one side of the glass enclosing the gaseous mixture. This improvement has the disadvantage that the light emitted by the fluorescence is spread over a wider area than the actual discharge in the gaseous mixture and tends to reduce the resolution of the display. Other improvements were made by O.Sahni in 1980 SID
International Syposium Digest of Technical
Papers, April 1980. In this case, temperature control of the mercury-seeded gas mixture must be provided. The need for temperature control creates significant practical limitations.

In the laser version, radiation in the blue and green parts of the spectrum is generated by an excimer laser using a high pressure gas mixture on the order of a few atmospheres and a high electron density discharge of at least 10 ¹⁴ electrons/cm ³ . A typical example is by G. Marowsky et al. in Journal
of Chemical Physics 75, 1153 (1981).

The object of the invention is to carry out an electrical discharge through a gaseous medium so that the excited or ionized substances originating from the gaseous composition of the medium form excimer molecules which, under the action of the discharge, fluoresce in the visible or ultraviolet region of the electromagnetic spectrum. It is an object of the present invention to provide an optical indicator with a

In known optical displays, the most typical example medium is neon, often mixed with small amounts of noble gases such as xenon or argon, which emit electromagnetic radiation in the orange and red regions of the visible spectrum. The radiation from neon is within the response range of photopic-adapted eyes, but invisible to dark-adapted eyes.
There has therefore been a need for mixtures that produce bright radiation in the visible region of the spectrum near the blue and green regions to which the dark-adapted eye is more sensitive. Conventional optical displays have not been able to provide sufficiently bright displays in desired spectral regions without incurring undesirable increases in cost.

Practical optical indicators use operating pressures at or near atmospheric pressure, so there is no need to strengthen large glass windows, and the voltages and currents are not very high, so they do not require expensive power supplies. These conditions are significantly different from the operating conditions of excimer lasers, which inherently use high voltages and very high electron current densities.

The inventors of the present application have developed an excimer molecule (for the purposes of the present invention, the term excimer shall mean both an excited molecule composed of homogeneous nuclei and an excited molecule composed of heterogeneous nuclei, but It has been found that gas mixtures can be generated with reasonable efficiency using pressures, voltages and currents suitable for plasma panels, thereby making optical indicators using such mixtures commercially practical. In the specific example where the excimer Xe ₂ Cl* is a radiative excimer, the excimer is formed by the following reaction sequence.

e+Xe−Xe*( ³ P ₂ )+e Xe*+Cl ₂ →XeCl*+Cl _{XeCl*+Xe+M→Xe 2 Cl} *+M be.

The inventors have also demonstrated that the shatter precursor molecule XeCI* can be used with great efficiency (10~
(in the range of 30%) and its efficiency is approximately 2~
It was found to be highest for an average electron temperature of 4 electron volts. Furthermore, triatomic excimer Xe ₂ CI＊
We have also found that the efficiency of is sufficiently high that brightness comparable to conventional neon Penning mixtures can be obtained at atmospheric pressure.

One excimer mixture was tested in the apparatus shown in partially exploded perspective view in FIG. In this device, glass plates 110 and 112 are connected to the X electrode 12.
An electrode that supports the 3 and Y electrodes 121 and emits light is arranged at a position where they intersect. The electrode is made from a gas mixture, e.g. 0.025 mm coated with an electron emissive layer consisting of 200 nm magnesium oxide.
A dielectric sheet 13 formed from a glass derivative of
0 and 132. The two dielectric sheets are separated by 0.1 mm by a spacer seal 140, and the space between them is separated by a gas 15.
0 is satisfied. Voltage pulses of controllable amplitude, 250 ns duration and 100 kHz repetition frequency were applied to the exposed ends of electrodes 121 and 123.
Capacitive coupling through the glass and magnesium oxide coating created a discharge in the gas where the electrodes crossed. The radiation due to the discharge was observed through a photometer with a CIE filter. The photometer used had a response close to that of the human eye to measure relative brightness as a function of pressure and temperature. Due to the discharge, the spectral components of the radiation become S-5
It was analyzed using a scanning monochromator with a photomultiplier response. As an example 20% xenon, 0.1
The test results shown in FIGS. 2 and 3 were obtained with a gas mixture having a nominal composition of % chlorine and the remainder neon.

FIG. 2 shows the spectral response of an excimer mixture measured at two different pressures.
Figure 2A shows the response at a pressure of 0.100 bar, peak 212 showing the characteristic spectrum of XeCI*, and peak 214 showing the neon-xenon spectrum.
Although it shows the characteristic spectrum of the strongest visible transition in the Penning mixture, peak 216, which shows the characteristic spectrum of Xe ₂ CI*, shows very little intensity. Figure 2B shows the response of the same mixture at a pressure of 0.667 bar, showing peaks 222 for XeCI and peaks 224 for neon, plus Xe ₂ CI
The * peak 216 indicates the dominant spectral output. It is noteworthy that the excimer material is excited with such efficiency that the neon peak 224 is relatively unnoticeable. In fact, the colors corresponding to neon's characteristic spectrum are invisible to the naked eye.

FIG. 3A shows the pressure dependence of the pulse amplitude for the embodiment of FIG. 1 producing a discharge with a width of approximately 1 mm, and FIG. 3B shows the pressure dependence of the pulse amplitude for two gas mixtures, namely the excimer gas mixture and The relative brightness of known neon-xenon Penning mixtures is shown. The discharge was observed through a CIE filter. Units are arbitrary. As can be seen from the illustrated test results, the above excimer mixtures operate similarly with conventional power supplies suitable for conventional optical indicators since the pulse amplitudes are substantially similar for the two gas mixtures. It can be used under certain conditions. Figure 3 shows that at pressures above 0.267 bar the brightness obtained with the excimer mixture exceeds that obtained with the Penning mixture.
It is expected that the brightness curve will continue to rise above 0.667 bar, but difficulties will arise in maintaining a discharge width of less than 1 mm at higher pressures. For applications that do not require a discharge width of 1 mm or less, it may be preferable to use a pressure of 0.667 bar or more.

FIG. 4 shows a seven segment character display tube 400 as another embodiment of the present invention. Seven cathode segments 404 are visible through the translucent anode 402 as shown in FIG. 4A. FIG. 4B shows this display tube in side view. The interior of the airtight case 410 is filled with an excimer gas mixture 420. A cathode 404 is provided inside the airtight case, and the cathode 404 is led into the airtight case 410 through a conductive wire passage 406 leading thereto. The cathode is driven by conventional display logic (not shown) which generates the required excitation voltage pulses.

The gaseous mixture may be any mixture of gases that reacts under the influence of an electrical discharge to form excimers that produce radiation in the desired spectral range. In addition to Xe ₂ Cl, suitable excimers that emit in the visible region include XeO, KrO, ArO, Xe ₂ Br and
It is XeF. Additional excimers that emit in the ultraviolet range and can be used with phosphorus include Ar ₂ , Kr ₂ ,
Xe ₂ , ArF, KrF, XeF, ArCl, KrCl and XeCl
It is. Compounds that can produce radiation with the highest efficiency contain at least one atom of one element from row 0 of the periodic table (e.g. argon, krypton and xenon) and from an element from row 7 (e.g. chlorine or fluorine). It is believed that it is a combination with at least one atom.

The role of neon in the reactions of the examples presented herein may be performed by any suitable buffer gas.
The role of CI ₂ is in chlorine-containing compounds such as HCI, CCI ₄
Or it can be carried out with chlorinated hydrocarbons which dissociate under the influence of an electrical discharge. In the case of excimer XeF, the fluorine donor may be _F2 or _NF3 .
Any electrical discharge can be used, such as AC, DC or RF.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of an embodiment of the invention.
FIG. 2 is a graph showing the wavelength dependence of an embodiment of the present invention at various pressures. FIG. 3 is a graph showing the pressure dependence of pulse amplitude and relative brightness for two different gaseous mixtures. FIG. 4 is a diagram showing another embodiment of the present invention. 110, 112... Glass plate, 123... X electrode, 121... Y electrode, 130, 132... Dielectric sheet, 140... Spacer seal, 150...
...Gas, 400...7 segment character display tube, 4
02...Translucent anode, 403...Cathode segment, 410...Hermetic case, 420...Excimer gas mixture.

Claims (1)

[Scope of Claims] 1. A gas-tight case having an optically transparent portion in the visible region of the electromagnetic spectrum, from which radiation can be emitted for optical display; and a plurality of electrodes; and configured to apply a voltage pulse to cause an electrical discharge to pass between at least two of the electrodes, and in response to the electrical discharge passing between at least two of the electrodes, the airtight case an electrode arranged to allow a portion of the radiation emitted therein to pass through the optically transparent portion of the hermetic casing; and at least one type of electrode hermetically sealed within the hermetic casing. A predetermined gaseous mixture containing a gas, wherein atoms of the at least one type of gas in the predetermined gaseous mixture react under the influence of the electric discharge, are de-excited by dissociation, and emit electromagnetic radiation. An optical indicator comprising: a gaseous mixture forming an excimer;