JP2004311171A - Electron multiplier element, and electron multiplier device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a practical electron multiplier element which can be manufactured at low cost, and an electron multiplier device using the same. <P>SOLUTION: The electron multiplier element 9 comprises a phosphor 12 emitting light by dint of kinetic energy of an accelerated electron injected, a support 11 transmitting the light from the phosphor 12 supporting the phosphor 12 at a surface 11a and emitting light from a surface 11b, and a photoelectric surface 13 converting the light of the phosphor 12 supported by the surface 11b. The phosphor 12 and the photoelectric surface 13 are arranged so that the number of electron emitted from the photoelectric surface 13 exceeds the number of electron incident onto the phosphor 12. The electron multiplier element converts electron into light and converts the light into electron thereafter. By the above, a practical electron multiplying function can be realized while imposing a thickness on the support 11. The manufacturing cost of the electron multiplier element 9 can be lowered by far in comparison with an MCP because of its simple structure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
[0002]
The present invention relates to an electron multiplier that multiplies and emits electrons, and an electron multiplier using the same.
[0003]
[Prior art]
In recent years, attention has been paid to a device using diamond as an electron multiplier used in an electron multiplier such as an electron tube. Diamond is attracting attention because diamond has a negative electron affinity and its secondary electron generation efficiency is enhanced. An example of an electron multiplier using such a diamond is reported in "Thin Solid Films 253 (1994) 151-156". In other words, a polycrystalline diamond thin film formed on a substrate of Mo, Pd, Ti, AlN, or the like by terminating the outermost surface with hydrogen is reported as an electron multiplier. Is being improved. This polycrystalline diamond thin film functions as a reflective secondary electron surface. However, it is known that when a primary electron is incident on such a reflective secondary electron surface, the hydrogen termination on the outermost surface of the reflective secondary electron surface is eliminated, and the secondary electron emission efficiency is reduced. .
[0004]
Therefore, a so-called transmission type secondary electron surface in which a surface on which primary electrons are incident and a surface on which secondary electrons are emitted is known as an electron multiplying element which can solve the above-mentioned disadvantages, for example, US Pat. No. 6,060,839 discloses a transmission type secondary electron surface using diamond.
[0005]
On the other hand, a microchannel plate (hereinafter, referred to as “MCP”) is known as an electron multiplier. The MCP is a device capable of multiplying secondary electrons while maintaining one-dimensional or two-dimensional position information.
[0006]
[Patent Document 1]
US Patent No. 6,060,839
[Non-patent document 1]
Thin Solid Films 253 (1994) 151-156.
[0007]
[Problems to be solved by the invention]
However, the transmission type secondary electron surface described in the above-mentioned US Pat. No. 6,060,839 cannot realize both a sufficient mechanical strength and a practical electron multiplication function. The following points can be considered for this reason. That is, on the transmission type secondary electron surface, the secondary electrons generated by the incidence of the primary electrons move to the emission surface on the opposite side to the incidence surface, and must be emitted from the surface. For this purpose, a very thin diamond film having a thickness of about the electron diffusion length (mean free path) is required. The diffusion length of electrons in the diamond film is found to be about 0.05 μm from the experimental result of photoelectron emission by the present inventors. Therefore, in order to efficiently emit secondary electrons on the transmission type secondary electron surface, the thickness of the diamond thin film needs to be approximately equal to the diffusion length, that is, approximately 0.05 μm. However, in practice, such a very thin diamond film cannot realize the above-mentioned transmission type secondary electron surface due to insufficient mechanical strength and poor uniformity. On the other hand, in order for a diamond thin film to have sufficient mechanical strength, a film thickness of at least about several μm is required, but in such a thick film, secondary electrons generated by the incidence of primary electrons are in contact with the incident surface. Can hardly reach the exit surface on the opposite side. As a result, the secondary electron emission efficiency becomes extremely low, and a practical transmission type secondary electron surface cannot be realized.
[0008]
When using an MCP as an electron multiplier, the MCP bundles and stretches a number of thin glass tubes, repeats the process of bundling and stretching a number of times again, then slices into a disk shape, polishes and cores the core glass part. Since it is manufactured through more complicated processes such as performing a reduction process and a heating process for emitting a secondary electron surface, the cost is extremely high. For the same reason, it is difficult to realize a large-area display which can be applied to a large flat display or the like.
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an electron multiplier capable of realizing a practical electron multiplier function while having sufficient mechanical strength and capable of being manufactured at low cost. An object of the present invention is to provide an electron multiplier using the same.
[0009]
[Means for Solving the Problems]
The present inventors have studied the above prior art in order to solve the above problems. As a result, it has been considered that it is difficult to solve the above problem as long as the electron multiplier performs electron multiplication according to the principle of converting primary electrons into secondary electrons. Therefore, the present inventors have further studied and found that, by constituting an ultraviolet phosphor with a nitride semiconductor, it is possible to realize a device having a relatively high emission intensity and a high-speed response. Then, based on such knowledge, the present inventors configured an electron multiplier by combining a phosphor, a support, and a photocathode, and after converting the electrons into light, It has been found that the above problem can be solved by performing electron multiplication in accordance with the principle of conversion into, and the present invention has been completed.
[0010]
That is, the present invention provides a phosphor in which accelerated electrons are injected, and which emits light based on the kinetic energy of the injected electrons, and which is transparent to light emitted from the phosphor and supports the phosphor. A support having a first surface, a second surface facing the first surface, and emitting light incident from the first surface; and the phosphor supported on the second surface of the support, And a photocathode that converts light emitted from the photocathode into electrons, wherein the phosphor and the photocathode are configured such that the number of electrons emitted from the photocathode is greater than the number of electrons incident on the phosphor. An electron multiplying element characterized in that:
[0011]
According to this electron multiplier, when the accelerated electrons are injected into the phosphor, light is emitted based on the kinetic energy of the electrons, and this light passes through the support and enters the photocathode, where Is converted to electrons on the surface. As described above, the electron multiplier of the present invention converts electrons into light and then converts them into electrons. Further, since the support is transparent to light emitted from the phosphor and light loss due to transmission through the support is small, the support can have a thickness. Further, the phosphor and the photocathode are configured so that the number of electrons emitted from the photocathode is larger than the number of electrons injected into the phosphor. For this reason, it is possible to realize a practical electron multiplying function while sufficiently securing the mechanical strength of the electron multiplier. Further, the electron multiplier of the present invention has a simple structure in which a phosphor and a photocathode are arranged on both sides of a support, and therefore its manufacture is extremely easy. For this reason, the manufacturing cost can be much lower than the manufacturing of the MCP.
[0012]
In the electron multiplier, the phosphor is preferably a compound semiconductor. In this case, it is possible to accurately adjust to an arbitrary emission wavelength as compared with the case where the phosphor is a material other than the compound semiconductor.
[0013]
The compound semiconductor is preferably a single crystal. In this case, since the compound semiconductor in the phosphor does not have a boundary surface unlike the case of a microcrystalline or polycrystalline material, non-radiative recombination at the boundary surface essentially does not exist, and the compound semiconductor is a single crystal. The luminous efficiency is much higher than in the case where there is no light. Further, since the compound semiconductor is a single crystal, the number of crystal defects is reduced, and the number of trapped electrons or holes due to the crystal defects is reduced. Therefore, the response speed of the phosphor increases.
[0014]
In the electron multiplier, the photocathode is preferably a compound semiconductor. In this case, the photocathode having a spectral sensitivity characteristic matched to the emission wavelength of the phosphor can be designed more accurately than when the photocathode is made of a material other than the compound semiconductor.
[0015]
It is preferable that the compound semiconductor is also a single crystal on the photoelectric surface. In this case, since the diffusion length of photoelectrons becomes longer, a photocathode having high electron emission efficiency can be realized.
[0016]
The compound semiconductor preferably has a negative electron affinity. In this case, the photocathode has high photoelectron emission efficiency.
[0017]
In the electron multiplier, it is preferable that the phosphor is formed directly on the first surface of the support and the photocathode is formed directly on the second surface of the support. In this case, the electron multiplication factor can be improved as compared with the case where the phosphor is formed indirectly on the first surface and the photoelectric surface is formed indirectly on the second surface.
[0018]
In the electron multiplier, the phosphor and the photocathode each include an electrode. In this case, when the electron source is arranged facing the phosphor and the anode is arranged facing the photocathode, a voltage can be applied between the phosphor and the electron source and between the photocathode and the anode. Thus, a practical electron multiplication function can be realized.
[0019]
Further, the present invention provides the electron multiplier, a vacuum vessel containing the electron multiplier, an electron source for emitting electrons to be injected into the phosphor of the electron multiplier, and the electron multiplier. An anode provided to face the photocathode and attracts electrons emitted from the photocathode; and a voltage for applying a voltage between the electron source and the phosphor and between the photocathode and the anode. And applying means.
[0020]
According to this electron multiplier, electrons are emitted from the electron source, and when a voltage is applied between the electron source and the phosphor by the voltage applying means, the electrons are accelerated and are applied to the phosphor of the electron multiplier. Injected. Then, light is emitted from the phosphor based on the accelerated kinetic energy of the electrons. The light passes through the support and is incident on the photocathode, and electrons are emitted from the photocathode. When a voltage is applied between the photocathode and the anode by the voltage applying means, the multiplied electrons are attracted to the anode. As described above, since the electron multiplier of the present invention includes the above-described electron multiplier, a practical electron multiplier function can be realized. Further, since the electron multiplier has sufficient mechanical strength, handling of the electron multiplier is easy in manufacturing the electron multiplier, and the electron multiplier can be manufactured very easily. In addition, since it is easy to increase the area of the electron multiplier, it is easier to increase the area of the anode or the electron source of the electron multiplier. Further, since the electron multiplier can be manufactured at a much lower cost than the MCP, the electron multiplier having the electron multiplier is much more expensive than the electron multiplier having the MCP. It can be manufactured at low cost.
BEST MODE FOR CARRYING OUT THE INVENTION
[0021]
Hereinafter, embodiments of the present invention will be described in detail. In the drawings, dimensions are appropriately enlarged or reduced in order to facilitate description of the present invention, and do not always correspond to actual dimensions. In the drawings, solid arrows indicate electrons, and broken arrows indicate light.
(1st Embodiment)
[0022]
FIG. 1 is a front view showing a first embodiment of an electron multiplier according to the present invention, and shows a flat display device as an electron multiplier having a built-in electron multiplier. FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. 3 is a partial side view showing an internal configuration of the electron multiplier of FIG.
[0023]
As shown in FIGS. 1 and 2, the flat display device 10 includes a vacuum container 1 having a flat shape, an opening 1 a is formed on a front surface of the vacuum container 1, and inside the vacuum container 1, The display unit 2 is provided so as to cover the opening 1a. The inside of the vacuum vessel 1 is in a vacuum state.
[0024]
As shown in FIG. 3, the display unit 2 includes a phosphor layer 3 and a face plate 17 that is transparent to light emitted from the phosphor layer 3. The surface of the phosphor layer 3 serves as an anode. Al thin film (not shown) is deposited. The vacuum vessel 1 is made of, for example, glass, the face plate 17 is made of, for example, sapphire, and the phosphor layer 3 is made of, for example, a nitride semiconductor.
[0025]
An electron source array (electron source) 4 for emitting electrons is provided inside the vacuum vessel 1 so as to face the display unit 2. An electron multiplier 9 for multiplying electrons is provided between the electron source array 4 and the display unit 2.
[0026]
The electron source array 4 has a plurality of electron-emitting portions 4a. These electron-emitting portions 4a have, for example, a so-called Spindt-type cone shape as shown in FIG. They are arranged in a dimension. A flat gate electrode 6 is arranged at a position facing the electron source array 4. The gate electrode 6 has a so-called XY address, and the gate electrode 6 has a plurality of openings 7 corresponding to the number of the electron emitting portions 4a. The tips of the plurality of electron-emitting portions 4a are arranged in these openings 7, respectively. When a voltage is applied between the gate electrode 6 and the electron source array 4, electrons are emitted from the tip of the electron emission portion 4a. The electron emitting portion 4a is made of, for example, a high melting point metal such as molybdenum, a semiconductor such as Si, or a carbon-based material such as carbon nanotube or diamond.
[0027]
As shown in FIG. 3, the electron multiplier 9 includes a flat support 11. The support 11 has a first surface 11 a facing the electron source array 4 and a support 11 facing the display unit 2. And a second surface 11b. The phosphor 12 is directly formed on the first surface 11a, and the photoelectric surface 13 is directly formed on the second surface 11b. Here, the reason why the phosphor 12 is formed directly on the first surface 11a and the photocathode 13 is formed directly on the second surface 11b is that the electron multiplying element 9 is formed as much as possible in consideration of the improvement in electron multiplication factor. In order to make it thinner. Since the electron multiplier 9 is housed in the vacuum vessel 1, the phosphor 12 and the photocathode 13 are present in the same space.
[0028]
Here, the phosphor 12, the support 11, and the photocathode 13 constituting the electron multiplier 9 will be described in more detail.
[0029]
First, the phosphor 12 will be described. The phosphor 12 may be any material that emits light based on the kinetic energy of the electrons emitted from the electron source array 4. Examples of such a phosphor 12 include a compound semiconductor and an alkaline earth metal. . Among these, a compound semiconductor is preferred from the viewpoints of adjustment of an arbitrary emission wavelength, high emission efficiency, and high-speed response. In this case, the phosphor 12 forms an electron-hole pair upon incidence of the electron beam, and emits light having a wavelength corresponding to the energy difference when the electron-hole pair recombine.
[0030]
Further, such a compound semiconductor is, for example, a nitride semiconductor (Ga _1-x Al _x ) _y In _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1), a group III-V compound semiconductor (Ga _1-x Al _x ) _y In _1-y As (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) and the like, among these, nitride semiconductors (Ga _1-x Al _x ) _y In _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) is preferred. Examples of such a nitride semiconductor include GaN, InN, AlN, and a mixed crystal thereof. However, since the emission wavelength of the phosphor 12 needs to be in a range where the photocathode 13 has sensitivity, (Ga _1-x Al _x ) _y In _1-y The composition ratios x and y are adjusted so that the energy gap of N is equal to or larger than the energy gap of the photocathode 13. In addition, as a compound semiconductor, (Ga _1-x Al _x ) _y In _1-y Of N, GaN (x = 0, y = 1) and Ga _y In _1-y N (0 <y <1) is preferred. This is because there is an advantage that relatively high quality and high luminous efficiency can be obtained.
[0031]
The compound semiconductor is preferably a single crystal. In this case, unlike the case where the compound semiconductor in the phosphor 12 is a microcrystalline or polycrystalline body, there is no boundary surface, so that non-radiative recombination at the boundary surface does not essentially exist, and the compound semiconductor is a single crystal body And the luminous efficiency is much higher than in the case where no When the compound semiconductor is a single crystal, the number of crystal defects is reduced, and the number of trapped electrons or holes due to the crystal defects is reduced. Therefore, when electrons are injected into the phosphor 12, a fast response speed is obtained.
[0032]
In order to improve the luminous efficiency of the phosphor 12, p-type or n-type impurities (for example, Si, S, Se, Mg, Zn, Be, etc.) may be doped.
[0033]
The phosphor 12 does not necessarily have to be a single film. A single heterostructure is formed using different compound semiconductor layers, or a compound semiconductor layer is formed of a compound semiconductor layer having a larger energy gap. A double hetero structure may be formed between both sides. Thereby, the luminous efficiency of the phosphor 12 can be further improved. In addition, by stacking a plurality of compound semiconductor layers to form a quantum well structure, a quantum wire structure, and a quantum dot structure to provide a carrier confinement structure, the luminous efficiency of the phosphor 12 can be further improved. The phosphor 12 is a nitride semiconductor (Ga _1-x Al _x ) _y In _1-y When the quantum well structure is formed by the N multilayer film, the composition (x and y) and the film thickness of each layer are adjusted so that the photocathode 13 has sensitivity to the emission wavelength of the phosphor 12.
[0034]
Next, the thickness of the phosphor 12 will be described. When the accelerated electrons are incident on the phosphor 12, the distance that the incident electrons reach is expressed using a range. It is also an indicator of the extent to which electron-hole pairs are generated. Since the range is almost proportional to the acceleration voltage, the optimum film thickness of the material is determined by the acceleration voltage used. In the case of a general compound semiconductor, the range is about 1 μm at an acceleration voltage of 10 kV and about 2 μm at an acceleration voltage of 20 kV. Here, considering that the phosphor 12 is used at an acceleration voltage of several kV to several tens of kV, the thickness of the phosphor 12 is suitably about 10 nm to 10 μm. However, when the thickness of the phosphor 12 is large, the light emission range is widened, so that the spatial resolution is reduced and the light emission efficiency is reduced due to the re-absorption of the emitted light. Therefore, the thickness of the phosphor 12 is more preferably in the range of 10 nm to 1 μm.
[0035]
Such a phosphor 12 can be formed, for example, by epitaxial growth on the first surface 11 a of the support 11.
[0036]
Next, the support 11 will be described. The support 11 may be a material that is transparent to light emitted from the phosphor 12. Such a material differs depending on the phosphor 12. When GaN is used as the phosphor 12, for example, sapphire is used as the support 11.
[0037]
The thickness of the support 11 is basically determined by the mechanical strength that can be handled, and varies depending on the material of the support 11. For example, when the support 11 is made of sapphire, the thickness of the support 11 is preferably from 10 μm to several mm. However, if the thickness of the support 11 is too small, there is a concern that the support 11 may be damaged during handling, and if the thickness of the support 11 is too large, there is a concern that the spatial resolution may decrease due to the spread of light emitted from the phosphor 12. Therefore, the range of 50 μm to 1 mm is more preferable.
[0038]
Next, the photoelectric surface 13 will be described. The photocathode 13 may be any as long as it can convert light into electrons and emit more electrons than the electrons injected into the phosphor 12. Such a photocathode 13 is, for example, a compound semiconductor. And alkali antimonide compounds. Of these, compound semiconductors are preferred because any spectral sensitivity characteristics can be obtained. In this case, there is an advantage that the sensitivity is higher than when the photocathode 13 is made of a material other than the compound semiconductor. Further, such a compound semiconductor is, for example, a nitride semiconductor (Ga _1-x Al _x ) _y In _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1), GaAs, GaAs _1-x P _x (0 ≦ x ≦ 1). Of these, nitride semiconductors (Ga _1-x Al _x ) _y In _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) is preferred. An example of such a nitride semiconductor is InGaN. However, since the photocathode 13 needs to have sensitivity to the emission wavelength of the phosphor 12, when the phosphor 12 has a single composition or a hetero structure, the energy gap of the photocathode 13 is The composition ratios x and y are adjusted so as to be equal to or smaller than the energy gap of No. 12. When the phosphor 12 is made of GaN, the compound semiconductor forming the photocathode 13 may be (Ga _1-x Al _x ) _y In _1-y Of N, InGaN (when x = 0 and y = 0) is preferable. The reason is that InGaN has a smaller energy gap than GaN, absorbs light emitted from the phosphor 12 sufficiently, and efficiently emits electrons.
[0039]
The compound semiconductor is preferably a single crystal. In this case, since the diffusion length of photoelectrons is longer than in the case where the compound semiconductor is a microcrystalline or polycrystalline body, a photocathode having high electron emission efficiency can be realized. The compound semiconductor preferably has a negative electron affinity. In this case, the photocathode 13 has higher photoelectron emission efficiency as compared to the case where the photoelectron has no negative electron affinity.
[0040]
When InGaN is used as the photocathode 13, it is preferable to dope InGaN with a p-type impurity (for example, Mg) in order to increase the photoelectron emission efficiency of the photocathode 13.
[0041]
Also, the phosphor 12 is made of (Ga) as a nitride semiconductor. _1-x Al _x ) _y In _1-y When a quantum well structure is formed using an N multilayer film, the composition of the photocathode 13 is adjusted so that the photocathode 13 has sensitivity to the emission wavelength of the phosphor 12.
[0042]
The thickness of the photocathode 13 is determined based on a balance between the light absorption length of the photocathode 13 and the diffusion length of photoelectrons excited thereby. The light absorption length depends on the wavelength of the incident light. When the incident light has a short wavelength, the light absorption length is short, and when the incident light has a long wavelength, the light absorption length becomes long. In particular, a photocathode having a negative electron affinity (hereinafter, referred to as a “NEA photocathode”), which is a compound semiconductor single crystal, has a longer diffusion length than a conventional alkali photocathode and can be formed thicker. . The thickness of the NEA photocathode using a general compound semiconductor is preferably in the range of 50 nm to 5 μm. In particular, in the case of a photocathode in the ultraviolet to visible light region using a nitride semiconductor as a compound semiconductor, since the light absorption length is relatively short, the film thickness is more preferably in the range of 80 nm to 500 nm.
[0043]
Such a photocathode 13 can be formed, for example, by epitaxial growth on the second surface 11 b of the support 11.
[0044]
The above-mentioned electron multiplier 9 converts electrons into light and then into electrons. Since the support 11 of the electron multiplier 9 is transparent to the light emitted from the phosphor 12 and the loss of light due to transmission through the support 11 is small, the support 11 may have a thickness. It is possible. Further, the phosphor 12 and the photocathode 13 are configured such that the number of electrons emitted from the photocathode 13 is larger than the number of electrons injected into the phosphor 12. For this reason, according to the electron multiplier 9, it is possible to realize a practical electron multiplier function while ensuring sufficient mechanical strength.
[0045]
That is, when the electron multiplying element is a photocathode that directly converts primary electrons into secondary electrons, increasing the thickness of the electron multiplying element significantly reduces the secondary electron emission efficiency. On the other hand, if the electron multiplier is made thin, practical secondary electron emission efficiency can be obtained, but sufficient mechanical strength cannot be obtained. That is, an electron multiplier that directly converts primary electrons into secondary electrons cannot achieve both a practical electron multiplier function and sufficient mechanical strength. On the other hand, the electron multiplier 9 has a configuration in which electrons are once converted into light by the phosphor 12 and then converted into electrons on the photocathode 13, and the diffusion length of electrons is generally extremely short. In contrast, light can pass through matter with much less loss than electrons. Therefore, the electron multiplier 9 can realize both a practical electron multiplier function and sufficient mechanical strength.
[0046]
In addition, since the electron multiplier 9 includes the two types of layers of the phosphor 12 and the photocathode 13, it is possible to increase the degree of freedom of the combination of the phosphor 12 and the photocathode 13.
[0047]
Furthermore, according to the electron multiplier 9, since electron multiplication can be performed while maintaining the position information of the electrons incident on the phosphor 12, the electron multiplier 9 has a two-dimensional electron multiplier similar to the MCP. Functions as a doubler.
[0048]
Further, as described above, the electron multiplier 9 functions as a two-dimensional electron multiplier similar to the MCP, but the electron multiplier 9 includes the phosphor 12 and the photocathode 13 on both sides of the support 11. , The manufacturing is extremely easy, and the manufacturing cost can be much lower than that of the MCP.
[0049]
Note that a buffer layer may be formed between the support 11 and the phosphor 12 in order to reduce distortion due to lattice irregularity and a difference in thermal expansion coefficient. The buffer layer is desirably a material that is transparent to the emission wavelength of the phosphor 12, and such a material is preferably AlN or AlGaN. Further, a buffer layer having the same configuration as described above may be formed between the support 11 and the photocathode 13 in order to reduce distortion due to lattice irregularity and difference in thermal expansion coefficient.
[0050]
An Al thin film (not shown) is deposited on the phosphor 11 as an electrode, and the photocathode 13 itself functions as an electrode. The surface of the photocathode 13 is coated with an alkali metal such as Cs or an oxide thereof in order to lower the work function and facilitate emission of electrons.
[0051]
Note that the electron source array 4 and the electron multiplier 9 are arranged close to each other in order to suppress the spread of the electrons emitted from the electron source array 4. The smaller the distance between the electron source array 4 and the electron multiplying element 9 is, the higher the spatial resolution becomes, but there is a possibility that a discharge occurs due to mechanical deformation or the like. It is. A focusing electrode (not shown) may be provided between the electron source array 4 and the electron multiplier 9 in order to suppress the spread of electrons from the electron source array 4. Further, the distance between the electron multiplier 9 and the display unit 2 is preferably set to about 0.5 to 5 mm in view of the balance between spatial resolution and mechanical deformation.
[0052]
As shown in FIG. 2, a spacer 18 is provided two-dimensionally between the electron source array 4 and the electron multiplier 9, and a spacer 18 is also provided between the electron multiplier 9 and the display unit 2. 18 are provided two-dimensionally. The spacers 18 are provided to suppress mechanical deformation of the electron multiplier element 9 due to atmospheric pressure when the inside of the vacuum vessel 1 is still at atmospheric pressure in the manufacturing process of the flat panel display 10. . Therefore, the shape of the spacer 18 is not particularly limited as long as it exhibits such a function, and examples of such a shape include a columnar shape, a prismatic shape, and a spherical shape.
[0053]
Further, the electrode pins 19a to 19e penetrate the vacuum vessel 1, and one ends of the electrode pins 19a to 19e are respectively connected to the electron source array 4, the gate electrode 6, the Al thin film on the phosphor 12, the photocathode 13, It is electrically connected to the Al thin film on the phosphor layer 3. Therefore, it is possible to make electrical contact with the outside while keeping the inside of the vacuum vessel 1 at a vacuum. Here, it is possible to apply a voltage between the electron source array 4 and the gate electrode 6 by electrically connecting the electrode pins 19 a and 19 b via the voltage applying device 8. By electrically connecting 19 b and 19 c via the voltage applying device 14, it is possible to apply a voltage between the gate electrode 6 and the Al thin film on the phosphor 12. Further, by electrically connecting the electrode pins 19d and 19e, it is possible to apply a voltage between the photocathode 13 and the Al thin film of the display unit 2.
[0054]
Next, the operation of the flat display device 10 having the above-described configuration will be described.
[0055]
When a voltage is applied between the electron source array 4 and the gate electrode 6 by the voltage applying device 8, electrons are emitted from the electron emitting portion 4a. At this time, a voltage is applied between the gate electrode 6 and the electron source array 4 by the XY address method, and electrons are emitted from a desired electron emitting portion 4a.
[0056]
Here, the electrons emitted from the tip of the electron emitting portion 4a are accelerated by applying a voltage between the gate electrode 6 and the Al thin film on the phosphor 12 by the voltage applying device 14, and are accelerated to increase the electron multiplying element. Nine phosphors 12 are injected. At this time, the voltage applied between the gate electrode 6 and the Al thin film on the phosphor 12 slightly varies depending on the thickness and the material of the phosphor 12, but is usually several kV to several tens kV. For example, if the thickness of the phosphor 12 is about 1 μm, the acceleration voltage may be 10 kV, and if it is about 2 μm, the acceleration voltage may be 20 kV.
[0057]
When the electrons are injected into the phosphor 12 in this manner, the phosphor 12 emits light having a peak intensity at a predetermined wavelength based on the kinetic energy of the electrons. When the phosphor 12 is, for example, a compound semiconductor, when electrons are injected into the phosphor 12, an electron-hole pair is formed in the phosphor 12, and when these recombine, a wavelength corresponding to the energy difference is generated. Light is emitted. This light passes through the support 11 and is incident on the photocathode 13. The incident light is absorbed by the photocathode 13 to excite photoelectrons. The excited photoelectrons travel on the photocathode 13, reach the emission surface opposite to the support 11, and are emitted again into the vacuum from the emission surface. The incident light is converted into electrons on the photocathode 13.
[0058]
Here, when a voltage is applied between the photocathode 13 and the Al thin film on the phosphor layer 3 by the voltage applying device 15, the photoelectrons emitted from the photocathode 13 are accelerated and applied to the phosphor layer 3. The light is incident, and visible light having a peak intensity at a predetermined wavelength is emitted by the kinetic energy of the electrons. This visible light passes through the face plate 17 and is emitted to the outside. Thus, a visible image is displayed on the display unit 2.
[0059]
In the flat panel display 10, electrons are multiplied by the electron multiplying element 9, so that high-luminance light emission can be obtained even at a lower acceleration voltage as compared with the case without the electron multiplying element 9. Further, since the acceleration voltage can be reduced, a simple and small power supply circuit can be used, and power consumption can be reduced. Further, since the acceleration voltage can be reduced, the deterioration of the electron source array 4 due to the ion feedback from the phosphor 12 is suppressed, and the life of the flat display device 10 can be extended.
[0060]
Also, since the manufacture of the electron multiplier 9 is extremely easy, the area of the electron multiplier 9 can be increased, and the screen of the flat display device 10 can be increased.
[0061]
Further, the electron multiplier 9 functions as a two-dimensional electron multiplier similar to the MCP. Therefore, by selecting the electron emitter 4a from which electrons are to be emitted and emitting the electrons, the electron multiplier 9 has a desired function in the display unit 2. A visible image can be displayed.
[0062]
Furthermore, as described above, the electron multiplier 9 is extremely easy to manufacture, and its manufacturing cost can be much lower than that of the MCP. Therefore, the manufacturing cost of the flat display device 10 can be much lower than that of the electron multiplier using the MCP as the electron multiplier.
[0063]
Further, the electron multiplier 9 has a sufficient mechanical strength as described above. For this reason, when manufacturing the photomultiplier 20, the electron multiplier 9 is easily handled, and the photomultiplier 20 can be manufactured efficiently.
[0064]
In the flat display device 10 of the above embodiment, the electron source array 4 including the plurality of electron emission portions 4a protruding from the substrate 5 is used. A planar electron source array using a nanotube or a diamond film may be used.
[0065]
In the above-described embodiment, the phosphor layer 3 has a light-emitting portion that emits three primary colors of R (red), G (green), and B (blue) corresponding to each electron-emitting portion 4a. You may. With such a configuration, color display can be performed on the display unit 2.
[0066]
Further, the flat panel display device 10 of the above embodiment may be used alone as a flat panel display element. However, several flat panel display devices 10 are combined in a two-dimensional manner and used as a single flat panel display element as a whole. Is also good. In this case, it is possible to obtain a flat display element having a larger screen.
[0067]
Further, in the above embodiment, the gate electrode 6 is provided between the electron source array 4 and the phosphor 12, but the gate electrode 6 is not always necessary and may be removed.
[0068]
Further, in the above embodiment, only one stage of the electron multiplying element 9 is provided inside the vacuum vessel 1. However, when a higher electron multiplication factor is required in the flat display device 10, it is not limited to one stage. A plurality of stages may be provided.
[0069]
Furthermore, in the above-described embodiment, the electron source array 4 includes the plurality of electron emission units 4a. However, when the electron multiplier of the present invention is not a flat display device but a fluorescent display device, the electron emission unit 4a 4a may be provided with one as shown in FIG. Here, the electron source array 4 and the Al thin film on the phosphor 12 are electrically connected via a voltage applying device 16.
(2nd Embodiment)
[0070]
Next, a second embodiment of the electron multiplier of the present invention will be described in detail with reference to FIG. In FIG. 5, the same or equivalent components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
[0071]
FIG. 5 is a schematic side view showing the internal configuration of the second embodiment of the electron multiplier according to the present invention. As shown in FIG. 5, the electron multiplier of the present embodiment is a photomultiplier 20. The photomultiplier 20 uses a photocathode 21 instead of the electron source array 4 and replaces the display unit 2. It differs from the flat display device 10 of the first embodiment in that an anode plate 22 is used.
[0072]
According to the photomultiplier 20, electrons emitted from the photocathode 21 by light are multiplied by the electron multiplier 9, so that a large signal current is detected in the anode plate 22. In addition, since the photomultiplier 20 has the same electron multiplier as the electron multiplier 9 of the first embodiment, the manufacturing cost can be sufficiently reduced. In addition, since the area of the electron multiplier 9 can be easily increased, the area of the photocathode 21 can be increased. Further, since the electron multiplier element 9 has a sufficient mechanical strength, handling becomes easy when manufacturing the photomultiplier 20, and the photomultiplier 20 can be manufactured efficiently.
(Third embodiment)
[0073]
Next, a third embodiment of the electron multiplier of the present invention will be described in detail with reference to FIG. In FIG. 6, the same or equivalent components as those in the first and second embodiments are denoted by the same reference numerals, and description thereof will be omitted.
[0074]
FIG. 6 is a schematic side view showing the internal configuration of the third embodiment of the electron multiplier according to the present invention. As shown in FIG. 6, the electron multiplier of this embodiment is an image intensifier (image intensifier) 30, and the image intensifier 30 uses a photocathode 21 instead of the electron source array 4. This is different from the flat display device 10 of the first embodiment in the point. Here, as the photocathode 21, one that converts not only light (visible light) but also high-energy rays such as γ-rays, X-rays, and ultraviolet rays into electrons is used.
[0075]
According to the image intensifier 30, the electrons emitted from the photocathode 21 are multiplied by the electron multiplier 9 by the light emitted from the object to be imaged, so that high-luminance light emission is observed in the phosphor layer 3. . Since the electron multiplier 9 functions in the same manner as the two-dimensional MCP as described above, the two-dimensional information of the object to be imaged incident on the photocathode 21 is not damaged by the electron multiplier 9 and the phosphor The layer 3 is reached. For this reason, it is possible to observe an enhanced image of the object on the display unit 2.
[0076]
Further, since the image intensifier 30 has the same electron multiplier as the electron multiplier 9 of the first embodiment, the manufacturing cost can be sufficiently reduced. In addition, since it is easy to increase the area of the electron multiplier 9, the image intensifier 30 can have a larger screen. Further, since the electron multiplier element 9 has a sufficient mechanical strength, handling is easy in manufacturing the image intensifier 30, and the image intensifier 30 can be manufactured efficiently.
(Fourth embodiment)
[0077]
Next, a fourth embodiment of the electron multiplier of the present invention will be described in detail with reference to FIG. In FIG. 7, the same reference numerals are given to the same or equivalent components as those of the first to third embodiments, and the description will be omitted.
[0078]
FIG. 7 is a schematic side view showing the internal configuration of the fourth embodiment of the electron multiplier according to the present invention. As shown in FIG. 7, the electron multiplier of this embodiment is an electron-implanted image intensifier 40. The image intensifier 40 uses a CCD 41 as a solid-state image sensor instead of the phosphor layer 3. The third embodiment differs from the image intensifier 30 of the third embodiment in that an anode 42 is used instead of the first embodiment.
[0079]
According to the electron-implanted image intensifier 40, since the electrons emitted from the photocathode 21 are multiplied by the electron multiplier 9 by the light emitted from the object, a large signal current is generated in each pixel of the CCD 41. Is detected. Further, since the electron multiplier 9 functions in the same manner as the two-dimensional MCP as described above, the two-dimensional information of the object to be imaged incident on the photocathode 21 is transmitted to the CCD 41 without being damaged by the electron multiplier 9. To reach. Here, the two-dimensional information of the object to be imaged by the electrons emitted from the photocathode 13 reaches the CCD 41 when a voltage is applied between the photocathode 13 and the anode 42. For this reason, the CCD 41 enables an enhanced image of the object to be observed to be observed.
[0080]
Further, since the electron implantation type image intensifier 40 has the same electron multiplier as the electron multiplier 9 of the first embodiment, the manufacturing cost thereof can be sufficiently reduced. In addition, since it is easy to increase the area of the electron multiplier 9, it is possible to increase the screen size of the electron implantation type image intensifier 40. Further, since the electron multiplier element 9 has a sufficient mechanical strength, it is easy to handle when manufacturing the image intensifier 40, and the electron implantable image intensifier 40 can be manufactured efficiently.
[0081]
【The invention's effect】
As described above, according to the electron multiplier of the present invention, it is possible to realize a practical electron multiplier function while ensuring sufficient mechanical strength. Further, since the electron multiplier of the present invention has a simple structure, it can be manufactured at a much lower cost than the MCP which has been used for the same purpose. Furthermore, since the electron multiplier of the present invention has a simple structure, it is extremely easy to manufacture, and therefore, the area can be increased.
[0082]
Further, according to the electron multiplier of the present invention, since the electron multiplier is provided, the manufacturing cost can be sufficiently reduced, and the area of the anode or the electron source can be increased. Further, since the mechanical strength of the electron multiplier is sufficiently ensured, handling is easy in manufacturing the electron multiplier, and the electron multiplier can be manufactured efficiently.
[Brief description of the drawings]
FIG. 1 is a front view showing a first embodiment of an electron multiplier according to the present invention.
FIG. 2 is a sectional view taken along the line II-II in FIG.
FIG. 3 is a partial side view showing an internal configuration of the electron multiplier of FIG. 2;
FIG. 4 is a partial side view showing a modification of the electron source array of FIG. 2;
FIG. 5 is a schematic side view showing an internal configuration of a second embodiment of the electron multiplier according to the present invention.
FIG. 6 is a schematic side view showing an internal configuration of a third embodiment of the electron multiplier according to the present invention.
FIG. 7 is a schematic side view showing an internal configuration of a fourth embodiment of the electron multiplier according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Vacuum container, 4 ... Electron source array (electron source), 9 ... Electron multiplication element, 11a ... 1st surface, 11b ... 2nd surface, 11 ... Support body, 12 ... Phosphor, 13 ... Photocathode, 8 , 14, 15, 16 ... voltage applying device (voltage applying means), 19a to 19e ... electrode pins (voltage applying means).

Claims (9)

Accelerated electrons are injected, and a phosphor that emits light based on the kinetic energy of the injected electrons,
A first surface that is transparent to the light emitted from the phosphor, supports the phosphor, and a second surface that faces the first surface and emits light incident from the first surface. A support having
A photocathode that is supported on the second surface of the support and converts light emitted from the phosphor into electrons;
The phosphor and the photocathode are configured such that the number of electrons emitted from the photocathode is greater than the number of electrons incident on the phosphor,
An electron multiplying element characterized by the above-mentioned. The electron multiplier according to claim 1, wherein the phosphor is a compound semiconductor. 3. The electron multiplier according to claim 2, wherein the compound semiconductor is a single crystal. The said photocathode is a compound semiconductor, The electron multiplier of any one of Claims 1-3 characterized by the above-mentioned. The electron multiplier according to claim 4, wherein the compound semiconductor is a single crystal. The electron multiplier according to claim 4, wherein the compound semiconductor has a negative electron affinity. The phosphor according to claim 1, wherein the phosphor is formed directly on the first surface of the support, and the photocathode is formed directly on the second surface of the support. 3. The electron multiplier according to claim 1. The electron multiplier according to claim 1, wherein each of the phosphor and the photocathode includes an electrode. An electron multiplier according to any one of claims 1 to 8,
A vacuum vessel containing the electron multiplier,
An electron source that emits electrons to be injected into the phosphor of the electron multiplier;
An anode provided to face the photocathode of the electron multiplier and attracting electrons emitted from the photocathode,
Voltage applying means for applying a voltage between the electron source and the phosphor, and between the photocathode and the anode,
An electron multiplier comprising:

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