RU2479065C2 - Light source - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: in a light source, having a vacuum envelope which is at least partially transparent for light and at least partially coated inside by an electroconductive layer and a phosphor layer, which form an anode, inside the vacuum envelope there is at least one cathode with external leads, characterised by that the cathode is in form of a straight tungsten filament with diameter of not more than 20 mcm, which is coated by a layer of material having thermoionic emission, wherein the length of the cathode filament is not less than the maximum size of the phosphor-coated area.

EFFECT: design of a simple, cheap to manufacture structure of an efficient cathodoluminescence source which is suitable for mass production on existing factories for producing incandescent lamps and/or cathodoluminescent indicators.

8 cl, 2 dwg

Description

The invention relates to lighting equipment and can be used for lighting, decorative lighting and light signaling, including color-coded.

The principle of operation of almost all modern light sources implies the conversion of electric current energy into light radiation. The most important parameter of any light source is the effectiveness of such a conversion. Depending on the physical principles used to produce visible light, this parameter can vary widely. In particular, the energy efficiency of converting energy into visible light in incandescent lamps is not more than 5%, which corresponds to a light output of 10-15 Lm / W. In this regard, various types of energy-saving light sources with higher efficiency are currently being developed. As a replacement for incandescent lamps (LF) in the world, compact fluorescent lamps (CFLs) and LED light sources (LEDs) are mainly used. Each of them has its own advantages and disadvantages.

Fluorescent lamps (see patent RU No. 2308783, IPC: H01J 61/56, H01J 61/34, publ. 10/20/2007; see patent RU No. 2354085, IPC: H05B 41/295, publ. 06/27/2009; patent RU No. 2195744, IPC ⁷ : H01J 61/44, H01J 61/04, published February 27, 2002) contain toxic mercury compounds, the use of which in household appliances is prohibited by the European RoHS directive. Currently, there is an exception to the directive allowing the use of CFLs with mercury contents up to 5 mg, but with the advent of a real alternative to replacing them with environmentally friendly energy-saving light sources, this exception can be eliminated. The light output of modern CFLs is 5-80 Lm / W with an energy efficiency of 20-25%. A lower value corresponds to lamps with a high color rendering index, i.e. the emission spectrum of which is close to optimal for the human eye.

LEDs have not yet found application in household lighting equipment. The reasons are primarily economic: the LED equivalent of a 100-watt LV costs today more than 2,000 rubles. As production increases, the cost of LEDs will decrease, but according to the most optimistic forecasts, it will reach an economically acceptable level no earlier than 2015. The use of LED light sources in household equipment is also complicated by the need to use stabilized power sources and massive metal radiators for efficient cooling of the crystal. Serial "white" diabetes has almost the same energy efficiency as CFL - 20-25%. The light output of serial LEDs is from 60 to 120 Lm / W, however LEDs with the highest light output values are unsuitable for household lighting due to the low color rendering index.

Other types of energy-saving light sources are being developed, one of which is able to compete with CFLs and LEDs in the market of household lighting products. These are cathodoluminescent high-voltage lamps (CVL), in which the phosphor is excited by a stream of accelerated electrons in a vacuum. The most important qualities of the waterline as a light source, along with their high energy efficiency, which can reach 30%, include full environmental safety, a wide color range, a wide range of operating temperatures, resistance to voltage fluctuations in the electrical network, the ability to control brightness in a wide range without loss of efficiency (see patent No. 2260224, IPC ⁷ : H01J 1/28, H01J 63/04, 04/20/2004).

In most of the well-known constructions of KVL, an electronic flow is created by using the effect of field (field-emission) emission (see patent EP No. 1498931, IPC: H01J 63/06, published on September 23, 2009). In contrast to thermionic, photoelectron, and other types of stimulated emission, field electron emission occurs without energy absorption in the material of the emitter — the cathode, which creates the prerequisites for creating highly efficient light sources. However, to obtain electron emission using field cathodes with a current density sufficient for practical use, it is necessary to create an extremely high electric field strength (10 ⁸ -10 ⁹ V / m) on their surface. This, in turn, requires the use of cathodes in the form of thin tips or blades that contribute to local amplification of the electric field. Acceptable from a practical point of view, the voltage value requires the creation of points and blades of submicron scale, which significantly increases the cost of their manufacture. In this case, electron emission is extremely unstable due to the high sensitivity of such tip structures to environmental conditions. These circumstances significantly complicate the use of tip and blade field cathodes in general-purpose devices.

Carbon materials are known in which field emission is observed at a significantly lower electric field strength (10 ⁶ -10 ⁷ V / m) due to the nanometer size of their structural elements, as well as due to the specific electronic properties of nanostructured carbon (see, for example, US patent No. 7432643, IPC: H01J 1/62, publ. 07.11.2008). The use of such materials as the emitter coating of the cathodes can significantly reduce the voltage applied between the anode and cathode to obtain electron emission.

The closest prototype analogue in technical essence is the well-known cathodoluminescent light source in the form of a vacuum diode with a field cathode made of 1 mm diameter wire with carbon nanotubes deposited on the surface of the wire (see JMBonard, T. Stoeckli, O. Noury, A.Chatelain, Apple. Phys. Lett. 78, 2001, 2775-2777).

However, electrovacuum devices with auto-electronic cathodes made of carbon materials have not yet found any significant distribution in the world. This is explained by the need to significantly improve the manufacturing technology of these cathodes in order to obtain acceptable values of durability and reproducibility of their characteristics in serial production.

The invention is as follows. The problem to which the present invention is directed, is to create a simple, cheap to manufacture design, economical cathodoluminescent light source, suitable for mass production at existing plants incandescent lamps and / or cathodoluminescent indicators.

These technical results are achieved by the fact that in a known light source containing a vacuum shell, at least partially transparent for the passage of light and at least partially coated inside with an electrically conductive layer and a phosphor layer forming the anode, inside at least at least one straight filament oxide cathode with external terminals, the straight filament oxide cathode is made in the form of a straight filament, while the length of the filament of the straight filament oxide cathode is not less than the maximum size portion coated phosphor.

In addition, the vacuum shell is made in the form of a glass cylinder, the inner surface of the glass cylinder is covered with a transparent electrically conductive layer and a phosphor, and the direct-burning oxide cathode is located along the axis of the cylinder; a thin metal film transparent to electrons is deposited on the surface of the phosphor layer; the vacuum shell is made in the form of a glass cylinder, one part of the inner surface of the glass cylinder forming the anode is coated with an opaque, light-reflecting metal layer, a phosphor layer is applied to the surface of the metal layer, and the other part of the inner surface of the glass cylinder is made transparent; the vacuum shell is made of two flat plates, a frame that seals the plates around the periphery, and sets the distance between the two plates, straight oxide cathodes are located between the plates at a distance that ensures uniform electron seeding of the anode; an opaque, light-reflecting metal layer is deposited on the inner surface of one of the flat plate, a phosphor layer is deposited on the surface of the metal layer, and the second plate has a transparent window for outputting light radiation of the phosphor; additionally introduced a metal plate with a developed surface having high thermal conductivity, the metal plate is tightly located on the inner side of the anode glass plate of the vacuum shell, a phosphor layer is deposited on the surface of the metal plate; the second plate has an electrically conductive coating transparent to light on the inner surface and is located at a close distance from direct-burning oxide cathodes, which allows, within certain limits, to control the magnitude of the electric current in the light source (lamp).

In this way:

1. A light source, which is a vacuum volume of any shape with a shell at least partially transparent to the passage of light and at least partially coated inside with an electrically conductive layer, on which a phosphor is deposited, forming the anode. At least one direct-burning oxide cathode is located inside the vacuum shell, which provides the inoculation of the phosphor surface with electrons. The vacuum shell can be made in the form of any geometric shape. The straight oxide cathode is made in the form of a straight filament, while the length of the filament of the straight oxide cathode is not less (i.e., more) than the maximum size of the portion (region) covered by the phosphor.

2. The vacuum shell according to claim 1 is made in the form of a glass cylinder, the inner surface of which, forming the anode, is coated with a transparent conductive layer of light, on which the phosphor is applied. Along the axis of the cylinder is a direct-burning oxide cathode formed on the basis of, for example, a tungsten core with a diameter of 8-30 μm.

3. On the surface of the phosphor layer according to claim 2, a thin metal layer is applied, transparent to electrons, having high energy and reflecting the generated light flux through the glass to the outside.

4. The vacuum shell according to claim 1 is made in the form of a glass cylinder, a part of the inner surface of which, forming the anode, is covered with an opaque metal layer reflecting the light inside the device, on which the phosphor is applied. The rest of the inner surface of the container is left transparent and serves as an optical window for the output of light radiation.

5. The vacuum casing according to claim 1 is formed by two flat plates, for example, glasses, and a frame located on the periphery of the vacuum shell, defining the distance between two flat plates. Directly heated oxide cathodes are located between the flat plates at a given distance with a step that ensures uniform electron seeding of the anode by electrons.

6. The inner surface according to claim 5 of one of the flat plates (anode plate) is coated with an opaque, light-reflecting metal layer on which the phosphor is applied.

7. On the inner side of the glass anode plate according to claim 5, a metal plate with a developed surface having a high thermal conductivity, on which a phosphor layer is applied, is tightly fixed.

8. The second glass according to claim 6, with an electrically conductive layer transparent to light, deposited on the inner surface, is located at a close distance from direct-burning oxide cathodes, which allows, within certain limits, to control the magnitude of the electric current in the light source — the lamp.

The invention is illustrated by drawings.

Figure 1 shows schematically a light source, the vacuum shell of which is made in the form of a glass cylinder.

Figure 2 shows schematically a light source, the vacuum shell of which is made in the form of two flat plates, for example, glass, with a frame around the perimeter.

In the drawings, the following notation:

1 - a vacuum shell;

2 - conductive layer;

3 - external output of the anode board;

4 - phosphor;

5 - direct-burning oxide cathode;

6 - emitting layer;

7 - external conclusions direct oxide cathode;

8 - luminous flux of a light source;

9 - transparent part of the bulb through which the light flux passes; 8 - optical window;

10 - the first glass plate;

11 - a second glass plate;

12 - frame;

13 - metal layer;

14 - transparent conductive coating;

15 - anode.

In the light source according to the invention, the vacuum shell 1 is made in the form of a glass cylinder (see figure 1), an electrically conductive layer 2, for example, of aluminum or another metal with good reflective properties, is applied to a part of the inner surface of the glass cylinder. This mirror layer of metal has an electrical connection with the electrode output to the external terminal 3 of the anode board. The anode 15 is formed by an electrically conductive layer 2 and a phosphor layer 4. A phosphor layer 4 is formed on the mirror electrically conductive layer 2, forming the anode 15. A direct-burning oxide cathode 5 is placed inside the vacuum shell 1 in the form of a rectilinear filament, while the length of the filament exceeds the maximum size of the portion coated with the phosphor . The surface of the metal wire is covered with an emitting layer 6 of a material having a high electron thermal emission efficiency, for example, oxides Ba, Ca, Sr. The direct oxide cathode 5 is expediently located along the longitudinal axis of the glass cylinder — the flask. The ends of the straight oxide cathode 5 are electrically connected to the electrodes that extend to the ends of the flask — the external leads 7 of the straight oxide cathode 5. The diameter of the cylindrical glass bulb - vacuum shell 1 is chosen so as to ensure at specified voltages applied between the anode 15 and the straight oxide cathode 5 emission current of a given value. Due to the presence of a specular reflecting surface of the anode 15 formed by the electrically conductive layer 2 and the phosphor layer 4, the cathodoluminescence light flux 8 will be directed towards the transparent (non-metallized) part of the surface of the vacuum shell 1 - a cylindrical glass bulb.

Figure 2 shows schematically a light source, the vacuum shell of which is made of two flat plates 10 and 11 and the frame 12, hermetically connecting the flat plates 10 and 11 on the periphery and specifying the distance between the flat plates 10 and 11. The flat plate 10 can be made of metal, metallized glass or ceramics. A phosphor layer 4 is formed on the metal surface, forming the anode 15. The metal layer 13 on the glass or ceramic flat plate 10 can be made continuous or consisting of electrically isolated sections - anodes 15 having individual external terminals. Straight oxide cathodes 5 are made in the form of metal, for example, tungsten filaments with an oxide layer 6 deposited on them, providing the required emission characteristics. Strands of oxide oxide cathodes 5 are placed above the surface of a flat plate 10 with anodes 15 so as to ensure uniform seeding of the anodes 15 by emitted electrons. The flat plate 11 has a transparent conductive coating 14. The vacuum shell 1 (sealed housing) of the light source has a transparent window for outputting the light flux 8.

The light source operates as follows.

Through the external terminals 7, a voltage is supplied to the direct-oxide oxide cathode 5. Electrons emitted from the direct-burning oxide cathode 5 are accelerated in the interelectrode space and cause the luminophore 4 to be luminous, deposited on the surface of the anode 15, formed by applying a layer of the phosphor 4 to the electrically conductive layer 2.

The light source in accordance with the present invention is a new type of light-emitting devices - lamps with increased energy efficiency compared to incandescent lamps. Lamps of this type can be used for domestic and industrial lighting, light signaling and other purposes, replacing known light sources.

The proposed light source made according to the invention has:

- higher efficiency than incandescent lamps;

- lower cost in terms of luminous flux than LED lamps;

- do not contain toxic components and environmentally hazardous materials, unlike fluorescent lamps.

Using the appropriate choice of a cathodoluminophore, light sources of this type can provide light with predetermined spectral characteristics without the use of light filters, while maintaining high energy efficiency.

Claims (8)

1. A light source comprising a vacuum shell at least partially transparent to the passage of light and at least partially coated inside with an electrically conductive layer and a phosphor layer forming an anode and at least one cathode with external terminals located inside the vacuum shell characterized in that the cathode is made in the form of a rectilinear tungsten filament with a diameter of 8 to 30 microns, coated with a layer of material having the property of thermionic emission, while the length of the cathode filament is not less than the maximum size ka shell coated with a phosphor. 2. The light source according to claim 1, characterized in that the vacuum shell is made in the form of a glass cylinder, the inner surface of the glass cylinder is covered with a transparent electrically conductive layer and a phosphor, and the direct oxide cathode is located along the axis of the cylinder. 3. The light source according to claim 2, characterized in that a thin metal film transparent to electrons is deposited on the surface of the phosphor layer. 4. The light source according to claim 1, characterized in that the vacuum shell is made in the form of a glass cylinder, one part of the inner surface of the glass cylinder forming the anode is coated with an opaque light-reflecting metal layer, a phosphor layer is deposited on the surface of the metal layer, and the other part is inner the surface of the glass cylinder is transparent. 5. The light source according to claim 1, characterized in that the vacuum shell is made of two flat plates, a frame that tightly connects the plates at the periphery and sets the distance between the two plates, straight oxide cathodes are located between the plates at a distance that ensures uniform electron seeding of the anode. 6. The light source according to claim 5, characterized in that an opaque light-reflecting metal layer is deposited on the inner surface of one of the flat plates, a phosphor layer is deposited on the surface of the metal layer, and the second plate has a transparent window for outputting light radiation of the phosphor. 7. The light source according to claim 5, characterized in that an additional metal plate with a developed surface having high thermal conductivity is introduced, the metal plate is tightly located on the inner side of the anode glass plate of the vacuum shell, and a phosphor layer is deposited on the surface of the metal plate. 8. The light source according to claim 6, characterized in that the second plate has an electrically conductive coating transparent to the light on the inner surface and is located at a close distance from the straight oxide cathodes, which allows, within certain limits, to control the magnitude of the electric current.

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