JPH0652653B2 - Light emitting electron tube - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electron beam type light emitting electron tube in which an anode and a cathode are provided in a low pressure gas filled tube.

BACKGROUND ART Recently, as shown in FIG. 4, a glass tube 2 is filled with an ultraviolet emission gas such as mercury vapor, and a cathode 3 heated by a filament 7 and a mesh-shaped anode 4 are provided. A fluorescent lamp that accelerates electrons between the cathodes, emits ultraviolet light by collision between electrons and gas atoms in the space S behind the anode, and converts the ultraviolet light into visible light by a fluorescent substance applied to the tube wall, JP-A-57-13036
Proposed in No. 4 etc. According to this method, since the current-voltage characteristic is positive, a current limiting element such as a ballast is unnecessary, and there is a possibility that a lightweight and compact fluorescent lamp can be realized.

However, in the above-mentioned conventional method, it is necessary to ionize a part of the mercury vapor in order to remove the space charge effect due to the electrons in the space behind the anode, and therefore a high anode voltage (about 20 V) is applied. Therefore, the electron in the tube has the optimum energy (about 6e) to excite the mercury atom to emit light.
Much higher energy than V) was given, which reduced the luminous efficiency of the lamp. Further, since the distance L ₂ from the anode to the tube wall needs to be sufficiently larger (for example, several times) than the mean free path L _m of electrons, there is a drawback that the shape of the lamp becomes large. Therefore, high efficiency,
The reality is that it is extremely difficult to realize a high-luminance, compact fluorescent lamp as expected.

[Object of the Invention] The present invention has been made in view of the above problems, and an object of the present invention is to realize a compact and highly efficient light emitting electron tube capable of emitting light with high brightness in a narrow space. There is.

DISCLOSURE OF THE INVENTION The light emitting electron tube according to the present invention, therefore, includes an elongated cathode and a cylindrical mesh-shaped anode surrounding the cathode.
It is arranged in a translucent tube having an ultraviolet light emission gas enclosed and a fluorescent substance coated on the inner surface, and magnetic field generating means is provided on both end faces of the anode. It is characterized in that it is possible to excite and emit gas atoms at a predetermined level in a narrow space between the anode and cathode by accelerating and swirling between them.

[Embodiment] FIG. 1 (a) is a perspective view of an embodiment of the present invention, and FIG. 1 (b) is a sectional view thereof, wherein 1 is a base and 2 is a gas for emitting light such as mercury vapor inside. Is a glass tube body in which a fluorescent substance is applied to the inner surface. An elongated cathode 3 is arranged in the center of the tubular body 2, and a cylindrical mesh-shaped anode 4 is concentrically arranged around the cathode 3. On the upper surface of the tube body 2, a disk-shaped permanent magnet 5 is provided with an anode 4
Is fixed so as to face the upper end surface of the anode 1, and an annular permanent magnet 6 is fixed to the upper surface of the base 1 so as to face the lower end surface of the anode 4. Both permanent magnets 5 and 6 are magnetized in the plate thickness direction and form a magnetic field orthogonal to the radial electric field between the anode and the cathode.

When a voltage is applied between the anode and cathode so that the anode 4 side becomes positive and the cathode 3 is heated by the filament, thermoelectrons emitted from the cathode 3 are accelerated toward the anode 4. At this time, the electrons receive a force at right angles to the traveling direction from the magnetic field applied in the axial direction, and swirl in a locus as shown in FIG. The pressure of the enclosed gas is set so that the distance L ₁ between the anode and the cathode is smaller than the mean free path L _{m of the} electrons (L ₁ ≦ L _m ), and therefore the electrons collide with gas atoms in one swirl. However, the magnitudes of the electric field and the magnetic field are set so that the turning radius R _r (Rahma radius) is slightly smaller than 1/2 of the anode-cathode distance L ₁ (L ₁ ≧ 2R _r ). If it says, an electron will rotate many times as shown in the figure, and during that time, it will collide with a gas atom and will be excited and light-emitted. For example, if this is mercury, 25
Ultraviolet radiation of 4 nm is emitted, and this ultraviolet light is converted into visible light by the fluorescent substance on the tube wall. The electrons, which have lost energy due to the collision, are accelerated again by the electric field and join the turn. Also, the electrons that have returned to the cathode during turning are not trapped because the cathode has a negative potential and head for the anode again, so the electrons are eventually confined in the narrow space between the anode and cathode,
While continuing the acceleration and deceleration motions, it waits for the opportunity of collision with gas atoms, and as a result, the gas can be excited and emitted extremely efficiently.

FIG. 3 shows a state in which the energy of the electrons changes, and the energy of the electrons changes momentarily between the cathode and the maximum reaching point L _o (= 2R _r ). By setting this maximum energy E _o to be slightly higher than the optimum excitation level (hatched portion) of the enclosed gas, highly efficient excited light emission is possible.

[Advantages of the Invention] As described above, according to the present invention, electrons can be confined in a narrow space while maintaining an optimum excitation energy level, so that highly efficient and high-luminance light emission is possible. Is performed inside the anode and does not require a wide drift space behind the anode as in the conventional example shown in FIG. 4, so that a compact light source can be realized and it is not necessary to send electrons into the space behind the anode. There is no need for ionization to neutralize the space charge, there is an advantage that the anode voltage can be lowered, and therefore the electrons can be controlled to the optimum energy level, and the light emission amount is the electron emission amount from the cathode. It can be easily controlled by filament heating (in the case of field emission, by the electric field on the cathode surface), and the anode voltage is low. Since there is no danger of increasing secondary electrons, and therefore no current limiting ballast is required, it is possible to reduce the size and weight,
Further, since the electron energy range can be set by the magnetic field regardless of the magnitude of the electric field, there is an advantage that there is a large degree of freedom in selecting the type of emission gas to be used and the emission spectrum.

[Brief description of drawings]

1 (a) is a perspective view showing an embodiment of the light emitting electron tube of the present invention, FIG. 1 (b) is a transverse sectional view of the same, FIG. 2 is an operation explanatory view of the same, and FIG. 3 is electron energy of the same. A graph showing the status,
FIG. 4 is a vertical sectional view of a conventional example. 1 is a base, 2 is a tubular body, 3 is a cathode, 4 is an anode,
5 and 6 are permanent magnets.

Claims (1)

[Claims] 1. An elongated cathode and a cylindrical mesh-shaped anode surrounding the cathode are arranged in a light-transmissive tube in which a gas for ultraviolet light emission is sealed and a fluorescent substance is applied to the inner surface thereof. A light emitting electron tube provided with magnetic field generating means on both end faces.