JP2006339012A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent positive ions beaten out by plunges of electrons into a phosphor and electrons emitted from cold-cathode electron emission sources from plunging into a gate electrode without needing a complicated structure; and to positively prevent damage of the cold-cathode electron emission sources. <P>SOLUTION: Openings 11 each having a size equal to or slightly larger than that of each electron emission area of the cold-cathode electron emission sources 6 are formed in the gate electrode 10, and an ion capture electrode 12, a gate plate 13 and the gate electrode 10 are sequentially stacked from the side of an anode electrode 15. Thereby, almost all the electrons emitted from the cold-cathode electron emission sources 6 are made to pass through the openings 11 and to reach the phosphor 16; the positive ions beaten out of the phosphor 16 can efficiently be captured by the ion capture electrode 12; discharge due to local degradation of the degree of vacuum caused by metal spatters and generation of gas can be avoided; and the damage of the the cold-cathode electron emission sources 6 can be prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting device that excites a phosphor with light emitted from a cold cathode electron emission source.

  In recent years, in contrast to conventional light emitting devices such as incandescent bulbs and fluorescent lamps, cold cathode field emission that causes phosphors to emit light by colliding the electrons emitted from the cold cathode electron emission source in vacuum with the phosphors at high speed. Type light-emitting devices have been developed and are expected to be used as field emission lamps (FEL) and field emission display devices (FED).

  This type of light-emitting device is one in which electrons are extracted by a gate electrode applied with a positive potential with respect to a cathode electrode, and are further made to emit fluorescent light by colliding electrons with a fluorescent plate electrode applied with a positive high voltage. When the gate electrode is placed opposite to the cathode electrode on which the cold cathode electron source is formed, some of the electrons extracted by the electric field between the cathode electrode and the gate electrode reach the phosphor and emit light. Although contributing, there are other problems such as jumping into the gate electrode and losing power unnecessarily, or causing metal spatter to damage the cold cathode electron emission source.

  In order to cope with such a problem, in Patent Document 1, a grid electrode (structure) in which a hole is formed in a substantially flat plate substantially parallel to the surface of the cathode electrode and the end of the hole protrudes toward the cathode electrode is related to FEL. A technique for forming a gate electrode) is disclosed. According to the technique of Patent Document 1, invalid electrons jumping from the cathode electrode to the grid electrode can be suppressed by making the electric field at the hole end higher than the electric field in the substantially flat plate region.

  Similarly, Patent Document 2 discloses a technique related to FEL in which a semicylindrical grid electrode partially having an opening surrounds a rectangular parallelepiped cathode electrode with a gap. The technique of Patent Document 2 is to prevent positive ions struck by the entry of electrons into the fluorescent plate electrode and prevent the discharge breakdown, but the trajectory of electron emission is calculated in advance. By designing and providing an opening, it is possible to improve the probability that emitted electrons pass through the opening without entering the grid electrode and enter the phosphor.

Further, in the FED or the like, the cathode electrode and the gate electrode are arranged at a very close distance by photolithography technology or the like so that electrons are not absorbed by the gate electrode. FIG. 5 shows a typical structure of the cathode side in the FED. An electron emission source 101 and an insulating layer 102 are formed on the cathode electrode 100, and a gate electrode made of a metal material is formed on the insulating layer 102. 103 is formed. The thickness A of the insulating layer 102 is, for example, 20 μm or less, and the opening dimension B of the gate electrode 103 is, for example, about several μ to several tens of μm.
JP 2004-207066 A JP 2004-220896 A

  However, in the technique of Patent Document 1, it is not always easy to maintain the processing accuracy of the hole end of the grid electrode, which may cause a cost increase. Similarly, in the technique of Patent Document 2, the shape of the grid electrode becomes slightly special, which is not only disadvantageous in terms of processing accuracy and manufacturing process, but also the emitted electrons enter the phosphor due to the opening design of the grid electrode. It is not always easy to equalize the probability of performing.

  In addition, the photolithographic technique in FED and the like is expensive to install and manufacture, and therefore, it is difficult to adapt to the FEL manufacturing process with a low product price. Furthermore, disposing the cathode electrode and the gate electrode at an extremely close distance leads to a drawback that ions moving at high speed in the vacuum vessel collide with the gate electrode and metal spatter is likely to occur. The cold cathode electron emission source may be damaged, or positive ions may collide with the cold cathode electron emission source and cause damage.

  The present invention has been made in view of the above circumstances, and without requiring a complicated configuration, positive ions from which electrons enter and strike the phosphor and electrons emitted from a cold cathode electron emission source to the gate electrode. An object of the present invention is to provide a light emitting device capable of preventing entry and reliably preventing damage to a cold cathode electron emission source.

  In order to achieve the above object, a light emitting device according to the present invention is excited by electrons emitted from the cold cathode electron emission source in a vacuum between the cathode electrode having the cold cathode electron emission source and the cathode electrode. A surface facing the cathode electrode between the cathode electrode and the anode electrode, which is exposed to the vacuum, and allows electrons emitted from the cold cathode electron emission source to pass through. A gate electrode having an opening, and an ion trapping electrode that is disposed on the anode electrode side of the gate electrode and captures positive ions emitted from the phosphor.

  At that time, the gate electrode is preferably formed in a laminated structure in which an ion trapping electrode, an insulating gate plate, and a gate electrode are laminated in order from the anode electrode side. The opening of the gate electrode is preferably larger than the electron emission region of the cold cathode electron emission source, and further, a conductive cathode mask covering the cathode electrode is preferably disposed around the electron emission region.

  The light emitting device according to the present invention prevents the entry of positive ions emitted from electrons into the phosphor and knocked out from the phosphor or electrons emitted from the cold cathode electron emission source into the gate electrode without requiring a complicated configuration. Damage to the cathode electron emission source can be reliably prevented.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 relate to an embodiment of the present invention, FIG. 1 is a basic configuration diagram of a light emitting device, FIG. 2 is a plan view showing a cathode electrode side of a gate electrode, and FIG. FIG. 4 is an explanatory view showing the relationship among a gate electrode, a cathode electrode, and a cold cathode electron emission source.

  As shown in FIG. 1, a light-emitting device 1 according to the present embodiment is a light-emitting device used as, for example, a planar field emission illumination lamp, and the inside of glass substrates 2 and 3 arranged to face each other at a predetermined interval is evacuated. In this vacuum state, the cathode electrode 5, the gate electrode 10, and the anode electrode 15 are arranged in this order from the base surface side to the light projecting surface side.

  The cathode electrode 5 is made of a conductive material formed on the glass substrate 2 serving as the base surface. For example, a metal such as aluminum or nickel is deposited by vapor deposition or sputtering, or a silver paste material is applied and dried. It is formed by firing. On the surface of the cathode electrode 5, an emitter material such as a carbon nanotube, a carbon nanowall, a spint type micro cone, a metal oxide whisker or the like is applied in a film shape to form a cold cathode electron emission source 6.

  In this embodiment, the cold cathode electron emission source 6 is patterned for each predetermined region, and a cathode mask 7 covering the cathode electrode 5 is arranged around the patterned region (electron emission region). The cathode mask 7 will be described later.

  The anode electrode 15 is made of a transparent conductive film (for example, ITO film) disposed on the back surface side of the glass substrate 3 serving as a light projecting surface, and cold cathode electron emission is performed on the surface facing the gate electrode 10 (cathode electrode 5). A phosphor 16 that is excited and emitted by electrons emitted from the source 6 is formed. The phosphor 16 is formed on the anode electrode 15 by, for example, a screen printing method, an ink jet method, a photography method, a precipitation method, an electrodeposition method, or the like.

  On the other hand, the gate electrode 10 disposed in the vacuum space between the cathode electrode 5 and the anode electrode 15 has a flat plate shape having an opening 11 through which electrons emitted from the pattern region of the cold cathode electron emission source 6 pass. Is formed. One surface of the gate electrode 10 is exposed in a vacuum facing the cathode electrode 5, and the other surface side captures positive ions emitted by collision of electrons with the phosphor 16. An electrode 12 is disposed.

  In this embodiment, an insulating gate plate 13 is interposed between the gate electrode 10 and the ion trap electrode 12, and the ion trap electrode 12, the gate plate 13, and the gate electrode 10 are integrally formed in order from the anode electrode 15 side. It is formed as a gate electrode having a laminated structure. This gate electrode is supported on the cathode electrode 5 via a supporter (not shown) arranged at a predetermined position.

  The gate electrode 10 is formed on the gate plate 13 as an electrode having a thickness of 1 mm or less, for example, by simple machining, etching, screen printing, or the like, using a conductive metal material such as nickel material, stainless steel material, amber material, As shown in FIG. 2, the cathode electrode 5 side is exposed in a vacuum to form a surface layer of the gate electrode on the cathode electrode 5 side. The gate plate 13 is formed of an insulating material such as ceramic or mica or by coating an insulating film on a metal plate.

  Moreover, the ion capture electrode 12 is formed by coating an ion getter material such as titanium, zirconium, vanadium, iron, or aluminum on a nichrome plate having a thickness of 1 mm or less, for example. As shown in FIG. 3, the ion capture electrode 12 is arranged on the anode electrode 15 side so as to cover a non-opening region other than the opening 11 of the gate electrode 10, and forms a surface layer on the anode electrode 15 side of the gate electrode. ing.

  Note that the gate plate 13 is not always necessary, and can be omitted when the gate electrode 10 and the ion trap electrode 12 are not insulated. For example, the gate electrode 10 and the ion trap electrode 12 can be omitted. The gate electrode 10 and the ion trapping electrode 12 may be insulated without using the gate plate 13 by disposing them slightly apart. Alternatively, a part of the gate electrode 10 may function as an ion trapping electrode by coating an ion getter on the surface of the gate electrode 10 on the anode electrode 15 side.

  In this embodiment, as shown in FIGS. 2 and 3, the opening 11 of the gate electrode 10 is a circular hole formed as the same or slightly larger than the pattern region of the cold cathode electron emission source 6 formed in a land shape. Is formed. As a result, almost all electrons emitted from the cold cathode electron emission source 6 can be passed to be effective electrons contributing to light emission, reducing power loss at the gate electrode 10 and realizing a lossless gate. It is possible.

  In order to effectively realize this lossless gate, the facing distance H between the gate electrode 10 and the cathode electrode 5 shown in FIG. 4, the dimension D1 of the pattern region of the cold cathode electron emission source 6, and the opening 11 of the gate electrode 10 are shown. It is necessary to appropriately set the relationship of the opening dimension D2.

  First, the facing distance H between the gate electrode 10 and the cathode electrode 5 is set to a specified lower limit value or more. This lower limit is a distance that can prevent the occurrence of harmful metal sputtering from the gate electrode 10 to the cathode electrode 5, and at the same time, the distance between the gate electrode 10 and the cathode electrode 5 is too short to effectively generate an electric field. This is a distance for avoiding that the number of electrons emitted from the cold cathode electron emission source 6 becomes extremely small, and is set to H = 0.1 mm to 5 mm, for example.

  Further, the relationship between the dimension D1 of the pattern region of the cold cathode electron emission source 6 and the opening dimension D2 of the opening 11 of the gate electrode 10 depends on the electric field intensity required for light emission of the phosphor 16 and the gate electrode 10 and the cathode electrode 5. It is set in consideration of alignment error and the like. For example, when the dimension D1 of the pattern area of the cold cathode electron emission source 6 is set to D1 = 0.1 mm to 5 mm, the opening dimension D2 of the opening 11 of the gate electrode 10 is set in a range of D2 = D1 to D1 + 1 mm. .

  In this case, the opening portion 11 of the gate electrode 10 and the pattern region (electron emission region) of the cold cathode electron emission source 6 are not limited to a circular shape, and may be other shapes such as a rectangular shape. good. The relationship between the dimensions D1 and D2 described above means that the gate electrode 10 side and the cold cathode electron emission source 6 side need only have a relationship in which the areas of the openings that are similar to each other are the same or slightly larger on the gate electrode 10 side. ing.

  Further, in realizing the lossless gate, the cathode mask 7 disposed around the pattern region of the cold cathode electron emission source 6 works effectively. The cathode mask 7 is formed of a conductive member similar to the gate electrode 10 and prevents concentration of the electric field on the periphery of the pattern region of the cold cathode electron emission source 6. By using the cathode mask 7, the electrons emitted from the cold cathode electron emission source 6 are prevented from entering the gate electrode 10 to reliably prevent the occurrence of metal sputtering, and are emitted from the cold cathode electron emission source 6. Almost all of the electrons that have passed through the opening of the gate electrode 10 reach the anode electrode 15, and the power loss at the gate electrode 10 can be effectively reduced as effective electrons contributing to light emission.

  Note that the cold cathode electron emission source 6 is uniformly formed on the cathode electrode 5 without patterning the cold cathode electron emission source 6, and the uniformly formed cold cathode electron emission source 6 is You may make it arrange | position the cathode mask provided with the opening part 11 of the shape similar to the opening part 11 of the gate electrode 10, and the area of the opening part 11 or less.

  In the light emitting device 1 described above, the anode electrode 15 is maintained at a positive high potential with respect to the cathode electrode 5, a predetermined gate voltage is applied from the gate electrode 10 to the cathode electrode 5, and the ion trapping electrode 12 is gated. Hold at a potential close to the voltage. As a result, electrons are emitted from the cold cathode electron emission source 6 into the vacuum, and the field-emission electrons are accelerated toward the anode electrode 15 and pass through the opening 11 of the gate electrode 10 as shown in FIG. The electron beam 20 collides with the phosphor 16 and excites the phosphor 16 to emit light.

  At this time, since the opening 11 of the gate electrode 10 is formed to be the same as or slightly larger than the electron emission region of the cold cathode electron emission source 6, almost all electrons emitted from the cold cathode electron emission source 6 are opened. 11 can pass through and reach the phosphor 16. Moreover, since the cathode mask 7 covering the cathode electrode 5 is arranged around the electron emission region of the cold cathode electron emission source 6, it is possible to prevent harmful metal sputtering and gas generation from the gate electrode 10, Wasteful power consumption due to invalid electrons can be effectively prevented. Furthermore, since the gate electrode 10 is arranged at an appropriate distance from the cathode electrode 5, the voltage applied to the gate electrode 10 does not become higher than necessary.

  Even when electrons enter the phosphor 16 and positive ions 21 are knocked out, the ions 21 are moved toward the cathode electrode 5 by the ion trapping electrode 12 disposed so as to face the anode electrode 15. It can be captured efficiently. Thereby, the entry of the ions 21 into the gate electrode 10 and the cold cathode electron emission source 6 is avoided, the metal sputter from the gate electrode 10 and the discharge due to local deterioration of the vacuum due to the generation of gas are avoided, and Damage to the cathode electron emission source 6 can be prevented.

  In particular, when considered for illumination with a large light emitting area, there is a high probability that electrons emitted from the cold cathode electron emission source and positive ions from the phosphor will enter the gate electrode, so the cold cathode is simple in structure. The light emitting device of the present invention that can effectively prevent damage to the electron emission source is useful, and can contribute to stabilization of the device and improvement of reliability.

Basic configuration diagram of light emitting device Plan view showing the cathode electrode side of the gate electrode Plan view showing the anode electrode side of the gate electrode Explanatory drawing which shows the relationship between a gate electrode, a cathode electrode, and a cold cathode electron emission source. Explanatory drawing which shows the typical structure of the cathode side in the conventional field emission display

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light-emitting device 5 Cathode electrode 6 Cold cathode electron emission source 7 Cathode mask 10 Gate electrode 11 Opening part 12 Ion capture electrode 13 Gate plate 15 Anode electrode 16 Phosphor

Claims (4)

A cathode electrode having a cold cathode electron emission source;
An anode having a phosphor that emits light when excited by electrons emitted from the cold cathode electron emission source in a vacuum with the cathode; and
A gate electrode having an opening through which electrons emitted from the cold cathode electron emission source are exposed in a vacuum between a surface facing the cathode electrode between the cathode electrode and the anode electrode;
A light emitting device, comprising: an ion capture electrode disposed on the anode electrode side of the gate electrode and capturing positive ions emitted from the phosphor.   2. The light emitting device according to claim 1, wherein the gate electrode is formed in a laminated structure in which the ion trapping electrode, an insulating gate plate, and the gate electrode are laminated in order from the anode electrode side.   3. The light emitting device according to claim 1, wherein the opening of the gate electrode has a size larger than that of the electron emission region of the cold cathode electron emission source.   4. The light emitting device according to claim 3, wherein a conductive cathode mask covering the cathode electrode is disposed around an electron emission region of the cold cathode electron emission source.

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