JPH0685314B2 - Light emitting electron tube - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a light emitting electron tube which emits light to the outside of a tube by exciting a light emitting gas sealed inside the tube by collision of electrons.

BACKGROUND ART Prior art includes, for example, JP-A-57-130364 and JP-A-
There are light emitting electron tubes such as those disclosed in JP-A-59-230254 and JP-A-60-1750.

On the other hand, the present inventors have proposed a magnetic field confinement type light emitting electron tube which confine electrons between the anode and the cathode and is capable of emitting light with high brightness.

In the former light emitting electron tube, the inside of the tube 5 is not completely vacuumed as shown in FIG.
With a low vacuum of about r, the electrons emitted from the thermionic emission type cathode 1 are accelerated by an electric field and the anode 2 is made to have an electron-passing shape, so that most of the electrons are converted to mercury vapor 3 in the back space 6. This collides to excite mercury to generate ultraviolet radiation, and the ultraviolet rays are applied to a phosphor (ultraviolet excitation type) 4 coated on the inner surface of the tube body 5 to perform desired visible light conversion. By the way, in this conventional example, the light is emitted only by diffusion of electrons in the back space 6 of the anode 2, and in reality, discharge ionization is necessary for space charge neutralization in order to sufficiently discharge electrons from the cathode 1, resulting in discharge. There is a drawback that the electron energy becomes considerably larger than the desired excitation due to the change.

On the other hand, the latter photo-emission electron tube can freely control the electron energy level regardless of the anode voltage, and essentially confine the electrons in the narrow space between the anode and the cathode, resulting in highly efficient and bright light emission. It consists of another possible construction principle.

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and an object of the present invention is to use the former light-emitting electron tube as a basic configuration to further enhance the emission brightness and emission efficiency and to provide a straight tube. Another object of the present invention is to provide a light emitting electron tube which emits light substantially uniformly over the entire tube body.

DISCLOSURE OF THE INVENTION The present invention encloses a small amount of light emitting gas so that a low vapor pressure is exhibited during operation in a straight tube-shaped light-transmissive tube having an airtight tube, and a thermoelectron is provided on one end side of the tube. The emission type cathode and anode are placed close to each other so that the space behind the anode is large so that the distance between the cathode and the anode is less than the mean free path of electrons and the mean space length behind the anode exceeds the mean free path of electrons. A pair of static magnetic field generation sources that apply a static magnetic field parallel to the axial direction connecting the cathode, the anode, and the back space and having a focusing property at the cathode end side and the opposite back space end side in the light emission electron tube set to Are closely attached to both ends in the axial direction of the tubular body, and the polarities of the close contact are different from each other, and the anode is formed in an annular shape whose center substantially coincides with the axial straight line passing through the cathode. Is set to be larger than the Larmor radius of the electron.

EXAMPLE As shown in FIG. 1, a tube body 5 is a straight tube, and the inside of the tube is airtight and transparent, and an ultraviolet excitation type phosphor 4 is applied to the entire inner surface of the tube wall. A small amount of light emitting gas such as mercury vapor 3 is enclosed in a tube body 5 having a length of about 40 mm and a total length of about 100 mm so as to have a low vapor pressure at the time of operation. The cathode 1 and the anode 2 are arranged close to each other to make a large space 6 behind the anode 2, and the distance l between the cathode 1 and the anode 2 is set to be equal to or less than the mean free path λ of electrons, for example, 1 cm so that positive characteristic discharge can be achieved. The average space length L behind 2 is set to, for example, 8 cm, which exceeds the mean free path λ of electrons, and is parallel to the axial direction connecting the cathode 1, the anode 2, and the back space 6, and behind the cathode 1 end side and the opposite side. It has a focusing property on the side of the space 6 and the radius of the electron is less than a few mm. Is added a static magnetic field of about 300 Gauss such that 10 mm. The static magnetic field is obtained by the magnets 7 closely arranged outside the both ends of the tubular body 5, the opposite polarities of these magnets 7 are different as shown in the drawing, and the distribution of the magnetic field lines of both magnets 7 is as shown in FIG. 1, the anode 2, and the back space 6 of the anode 2 are substantially parallel to the axial direction, and both ends are converging. The anode 2 has, for example, a diameter of 30 mm
It is formed of a nickel ring and has a structure in which the central portion penetrates. The cathode 1 is formed of a barium-impregnated indirectly heated cathode.

Next, the operation of the light emitting electron tube of the present invention will be described with reference to FIGS.

First, when the cathode 1 is appropriately heated, and the voltage of the DC power source 5 for acceleration is applied to the anode 2, for example, about 30 V, electrons are ejected from the cathode 1, and the ejected electrons are the magnetic lines of force of the magnet 7 as shown in FIG. While wrapping around (indicated by a broken line in FIG. 2), that is, in a trapped form, it makes a swirling motion and collides with the mercury vapor 3 which is a light emitting gas on the way to change its direction or loses energy, but the neighboring magnetic field lines Then, the electric field is accelerated again. In this way the anode 2
After passing through, since the electrons move so as to be wrapped around the magnetic field lines, there is little diffusion loss to the tube wall, and even if the back space 6 of the anode 2 is long, the electrons can reach far,
The entire tubular body 5 emits light widely and uniformly. Further, since electrons reciprocate along the electric field while reciprocating along the electric field while being wrapped around the magnetic field lines, the mean free path of each electron becomes small as if the atmospheric pressure was raised, and the mercury vapor, which is a light-emitting gas, 3 Since the chances of collision excitation with and increase the diffusion loss to the tube wall, the utilization efficiency of electrons in the back space 6 increases, and as a result, the light emission amount and the light emission efficiency improve.

Here, since the light emission distribution is substantially proportional to the instantaneous electron density distribution, it can be seen that light emission corresponding to the substantially magnetic force line distribution is obtained as in the hatched portion in FIG. 4 (a). FIG. 2B is a graph showing the brightness level of each part of the tubular body 5. Of course, if the magnetic field is strengthened, the electrons will be focused in the axial center,
In the case of the straight tubular body 5, desired light emission can be obtained with high brightness light emission.

The approximate energy distribution of electrons penetrating near the anode 2 is as shown in FIG. 5 (a). In particular, when the anode 2 is annular as in the present embodiment, the potential of the central portion becomes low, and since a static magnetic field is applied, electrons are focused and pass through the central direction of the anode 2, as shown in FIG. In the case of this embodiment using the mercury vapor 3 as the light emitting gas, the electron energy distribution becomes 5 to 10e, which is desirable for the excitation of ultraviolet rays of 254 nm.
The luminous efficiency is improved by approaching V. In the figure, e is an electron and E is an electric field.

Thus, in this example, a light emission amount of about 200 lm and a brightness of about 15,000 Cd / m ² were obtained with an input of about 5 W of lamp power excluding cathode heating power.

6 (a) and 6 (b) show the luminescence distribution and the brightness level when a mesh is used for the anode 2 without applying a static magnetic field. In this case, the luminescence intensity is weakened as the distance from the anode 2 increases. It can be seen that the whole body 5 does not emit light uniformly. Further, in FIGS. 7 (a) and 7 (b), a static magnetic field is not applied,
It shows an electron energy distribution when a mesh is used for the anode 2, and the electron energy is high in this case.

Although the mercury vapor 3 is used as the light emitting gas in the above embodiment, it is of course possible to use cesium, sodium or the like, and excitation light emission is performed without using the phosphor 4 applied to the inner peripheral surface of the tube wall. Of course, the emitted light may be directly emitted to the outside of the tube body 5.

EFFECTS OF THE INVENTION The present invention provides a light emitting electron tube configured as described above,
A static magnetic field that is parallel to the axial direction connecting the cathode, anode, and back space and has a focusing property at the cathode end side and the opposite back space end side is applied, so that the electrons accelerated by the anode are swirled around the magnetic field lines. Since both ends of the tube can be moved reciprocally along the electric field, the mean free path of electrons per electron is reduced to increase the chances of collision excitation with the light emitting gas, and to the tube wall. It is possible to reduce the loss due to the collision of the electrons, and as a result, the utilization efficiency of electrons in the back space is increased, and as a result, the light emission amount and the light emission efficiency are improved. Even if it is long, electrons can reach far enough, so that the entire straight tubular body can be made to uniformly emit light. Furthermore, since the anode is formed in a ring shape whose center almost coincides with the axial straight line passing through the cathode, and the inner radius of the anode is set to be larger than the Larmor radius of the electron, the electron swirls near the above straight line. While passing through the inside of the anode, which has a lower potential than the anode,
The energy of electrons becomes low on average, and there is an advantage that the light emission efficiency can be improved by reducing the power consumption.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, FIG. 2 is a magnetic field line distribution diagram for explaining the same operation as above, FIG. 3 is an example of an electron movement locus for explaining the same operation as above, and FIG. ) (B) is an explanatory view of the light emission distribution of the above, FIG. 5 (a) (b) is an explanatory view of the distribution of potential and electron energy near the anode, and FIG. 6 (a).
FIG. 7B is an explanatory view of the light emission distribution of the conventional example, FIG. 7A.
(B) is an explanatory view of the distribution of electric potential and electron energy near the anode, and FIG. 8 is a schematic configuration diagram of a conventional example, where 1 is a cathode, 2 is an anode, 3 is mercury, 5 is a tube, and 6 is The back space, 7 is a magnet, λ is the mean free path of electrons, l is the distance between the cathode and the anode, and L is the mean length of the back space.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-19049 (JP, A)

Claims (4)

[Claims] 1. A straight tube-shaped light-transmitting tube whose airtight inside is filled with a small amount of light emitting gas so as to exhibit a low vapor pressure during operation, and a thermoelectron emission type is provided at one end of the tube. Place the cathode and anode close to each other to take a large space behind the anode,
In a light emitting electron tube in which the distance between the cathode and the anode is less than or equal to the mean free path of electrons, and the mean space length behind the anode exceeds the mean free path of electrons, the axial direction connecting the cathode, anode and back space A pair of static magnetic field generators that apply a static magnetic field that is parallel and has a converging property on the cathode end side and the opposite back space end side are closely arranged at both ends in the axial direction of the tubular body, and the polarities of closely contacting each other are set. A light emitting electron tube, wherein the anodes are formed in a ring shape whose center is substantially aligned with a straight line in the axial direction passing through the cathode, and the inner radius of the anode is set to be larger than the Larmor radius of electrons. 2. The intensity of the static magnetic field is determined by the Larmor radius of an electron.
The light emitting electron tube according to claim 1, wherein the light emitting electron tube is set so as to have a diameter of several mm to several tens mm. 3. The light emitting electron tube according to claim 1, wherein the light emitting gas is mercury. 4. The light emitting electron tube according to claim 1, wherein the static magnetic field generating source is a magnet.