JPH031774B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is directed to an image tube, an image dissector tube, a streak tube, etc. equipped with a photocathode,
The present invention relates to a photoelectric conversion tube in which a mesh electrode is fixed to the tube by a support so as to face the photocathode, and a method for manufacturing the same.

In particular, the present invention provides a photoelectric conversion tube and a photoelectric conversion tube having a structure in which no unnecessary alkali metal remains in the tube, so as to prevent the occurrence of voltage resistance failure caused by alkali metal remaining in the tube in connection with the production of photocathode, etc. It relates to its manufacturing method.

(Prior Art and Problems to be Solved by the Invention) First, the problems of the prior art will be briefly described with reference to FIG. The figure is a schematic diagram showing a front end portion of the photoelectric conversion device cut away.

In FIG. 1, 25 and 26 indicate side walls of the glass airtight container, and 24 indicates a face plate forming the bottom surface of the glass airtight container. Face plate 24
A photocathode 23 is provided on the inner surface of the tube.

27 is a metal annular face plate support member that supports the face plate. This member 27
also serves as the lead-in line for the photocathode. Reticular electrode 22
The glass tubes 25, 2 are connected by the cylindrical support 20.
It is fixed at 6. This cylindrical support 20 also serves as an introduction line for the mesh electrode 22.

The photocathode 23 is, for example, a face plate 24.
An alkaline antimony photocathode is obtained by forming an antimony layer thereon and introducing an alkali metal from an inlet tube (not shown) located to the right in the figure. At this time, the amount of alkali metal relative to antimony must be strictly controlled.

Also, excess alkali metal must be promptly removed.

Since alkali metals move to areas with lower temperatures, the supply and removal of alkali metals is performed using temperature gradients.

In order to form the photocathode 23, an attempt is made to supply as much alkali metal as possible to the amount of antimony between the deep dish cylindrical support 20 and the glass tube 25 forming one side wall of the airtight container. Some of the residual alkali metals that have entered are difficult to remove.

The means of removal is to increase the temperature of the part where it is stored, but it is not easy to heat just that part. Even if efforts are made to eliminate the alkali metal as much as possible, the alkali metal will not be discharged unless it passes through the mesh electrode 22.

Therefore, the photocathode 23 is exposed to the alkali metal again.

As a result, the sensitivity of the photocathode decreases,
A problem arises in that the photocathode 23 emits more thermionic electrons.

If left to accumulate, the alkali metal will move inside the tube after sealing off and will adhere to all electrodes and the inner wall of the airtight container. Thermionic electrons are easily emitted from the surface of the electrode to which alkali metal is attached.

During operation (high voltage is applied between the electrodes) thermionic electrons collide with the electrodes. The alkali metal vaporizes and is ionized by thermionic collision, leading to the emission of secondary electrons.

In such a state, discharge due to the electrostatic field is likely to occur, making it impossible to apply a necessary and sufficient voltage between the electrodes. Furthermore, the generation of a large amount of electrons unrelated to the incident light is not itself desirable.

If the above-mentioned necessary and sufficient voltage is not applied, (a) the electrons will not be able to follow the designed trajectory. This causes blurring of the image on the fluorescent surface.

(b) If no voltage is applied between the photocathode 23 and the mesh electrode 22, time resolution will deteriorate in the streak tube.

(c) If a sufficient voltage is not applied between the photocathode and the fluorescent surface, problems such as the inability to obtain the necessary brightness on the fluorescent surface will occur.

Further, when a discharge occurs, secondary electrons generated by ionization of the gas collide with the fluorescent surface, causing it to glow. As a result, problems such as lowering the contrast of the image occur.

The reason for the above-mentioned residual alkali metal is considered to be the shape of the cylindrical support 20.

However, this shape could not be avoided for the following reasons. First, (a) the mesh electrode is close to the photocathode and needs to be kept strictly parallel, so it requires strong support.

(b) The fixed portion between the support 20 and the walls 25 and 26 of the airtight container must be separated from the fixed portion between the support 27 of the face plate (which also serves as a lead wire for the photocathode 24) and the airtight container 25. If this distance is not maintained, it will be impossible to seal the glass and metal because the glass will break due to the difference in thermal expansion coefficients.

SUMMARY OF THE INVENTION An object of the present invention is to provide an improved photoelectric conversion tube and method for manufacturing the same that can solve all of the above-mentioned problems.

(Means for Solving the Problems) In order to achieve the above object, a photoelectric conversion tube according to the present invention includes a photocathode formed on one bottom inner wall of an airtight container, and a photocathode connected to a side wall of the container at a flange. A photoelectric conversion tube including a support having an opening at the bottom of a deep dish-shaped portion on the photocathode surface side, and a mesh electrode provided in the opening close to the photocathode, the mesh electrode, the support one or more penetrations provided in the side surface of the support body, an annular space formed between the outer circumference of the side surface of the support body and the inner circumference surface of the airtight container of the first space on the photocathode side divided by the body; The hole communicates with a second space inside the container, and the second space is provided with a supply section for alkali vapor during the photocathode manufacturing process and a tip tube section for discharging the residual alkali.

Further, the method for manufacturing a photoelectric conversion tube according to the present invention includes a photocathode on one bottom inner wall of an airtight container, a mesh electrode disposed close to the photocathode, and a flange connected to the side wall of the container at the photocathode surface. A method for manufacturing a photoelectric conversion tube including a support for supporting the mesh electrode at the bottom of a side deep dish-shaped portion, the method comprising: a first space on the photocathode side divided by the mesh electrode and the support; A ring-shaped space formed between the outer circumference of the side surface of the support body and the inner circumference surface of the airtight container is communicated with a second space inside the container through one or more through holes provided in the side surface of the support body, In the cathode manufacturing process, alkaline vapor is supplied from the second space side to form a photocathode, and before sealing off the chip provided in the second space, the photocathode is supplied from the first space side after the photocathode is formed. An excess alkali removal step is provided in which residual alkali vapor is removed via the one or more through holes and the second space.

(Example) The present invention will be described in more detail below with reference to the drawings.

FIG. 2 is a cut end view showing an image tube, which is an embodiment of the photoelectric conversion tube according to the present invention, cut along a plane including the tube axis. Figure 3 shows the support removed.
It is a partially broken view.

The face plate 4 is the same plate support member 1
2 on the front end surface of the tube.

A multi-alkali photocathode 3 with a diameter of 16 mm is formed on the inner surface of the face plate.

The mesh electrode 2 is supported by a support 1 shown in FIG. 3 and fixed to the container.

As shown in FIG. 3, the support 1 is shaped like a deep dish and has a flange 1c which also serves as an attachment part and an introduction line, and has an opening 1b in the center.

This opening diameter is 29.0 mm in this example. The mesh electrode 2 is placed 3 mm apart from the photocathode 3, which has a mesh of 750 mesh/inch. A plurality of openings 1a are provided in the cylindrical surface of the support 1.

The focusing electrode 5 is provided with an opening 5a that is used when forming a photocathode.

A chip 10 is provided on the tube wall corresponding to the opening 5a, and during the manufacturing process, this chip 10 forms a supply passage for a supply source of antimony and alkali metal, and is connected to a vacuum pump.

6 is an anode, 9 is a bulk getter, and 7 is a microchannel plate (MCP).

A fluorescent surface 8 is formed on the inner surface of the fluorescent surface plate 11.

Next, a method for manufacturing the photoelectric conversion tube will be briefly described.

Excess alkali metal is recovered before sealing off the chip 10 provided on the tube wall.

The surroundings of the support 1 and the mesh electrode 2 are kept at a relatively high temperature, and a rod with a temperature lower than that temperature is introduced into the anode 5 from the chip 10 side, and the alkali metal that has been moved due to the temperature gradient is transferred to the rod. Attach it and pull it out.

In the photoelectric conversion tube having the structure according to the present invention, the alkali metal in the space surrounded by the mesh electrode 2, the support 1, the photocathode 3, and the inner wall of the airtight container moves to the space on the chip 10 side through the plurality of holes 1a. I am made to do so.

Therefore, the alkali metal in the space is recovered in a state where it hardly comes into contact with the photocathode 3.

Next, in the structure described above, the performance of the example device manufactured by the manufacturing method described above will be evaluated.

In the above-described embodiment device, the voltages supplied to various electrodes are as follows.

K (photocathode) - 10KV, M (mesh electrode) - 5KV,
F (focusing electrode) -8.7KV, A (anode) 0V,
The input electrode of MCP7 is 0V, the output electrode is 1KV, and the PS (fluorescent surface) is 4 to 5KV.

A comparison was made between a device having the above configuration but without the hole 1a described above, a device having the same structure manufactured under the same conditions, and a device having the above configuration.

In a device without holes 1a, when the fluorescent surface is in a dark state and the potential difference between MK is about 1 KV, a discharge occurs between the photocathode 3 and the mesh electrode 2, and the fluorescent surface becomes uniformly bright.

On the other hand, in the device of the embodiment, such a phenomenon does not occur even at 5KV.

(Effects of the Invention) As described above in detail, the photoelectric conversion tube according to the present invention has a structure that can significantly improve the withstand voltage between the mesh electrode 2 and the photocathode 3.

Therefore, it is possible to provide a sufficient potential difference between the mesh electrode 2 and the photocathode 3, and a photoelectric conversion tube with excellent operating characteristics can be provided.

Further, according to the method for manufacturing a photoelectric conversion tube according to the present invention, excess alkali can be effectively removed to provide a photoelectric conversion tube with excellent characteristics.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining the problems of a conventional photoelectric conversion tube, FIG. 2 is an enlarged cut-away end view showing an embodiment of the photoelectric conversion tube according to the present invention, and FIG. 3 is a diagram showing a mesh electrode support taken out. It is a partially broken view. DESCRIPTION OF SYMBOLS 1...Support, 1a...Through hole, 2...Mesh electrode, 3...Photocathode, 4...Face plate, 5...Focusing electrode, 6...Anode, 7...Microchannel plate (MCP), 8... Fluorescent surface, 9... Bulk gettuta,
DESCRIPTION OF SYMBOLS 10... Chip, 11... Fluorescent face plate, 12... Face plate support member, 20... Cylindrical support, 22... Network electrode, 23... Photocathode, 24
...Face plate, 25, 26...Glass tube, 27...Face plate support member.

Claims (1)

[Scope of Claims] 1. A photocathode formed on one bottom inner wall of an airtight container, and a support having an opening at the bottom of a deep dish-shaped portion connected to the side wall of the container at a flange and facing the photocathode side. a photoelectric conversion tube including a body and a mesh electrode provided in the opening in proximity to the photocathode;
A ring-shaped space formed between the outer circumference of the side surface of the support body and the inner circumference of the airtight container of the first space on the photocathode side divided by the mesh electrode and the support body is formed on the side surface of the support body. communicating with a second space in the container through one or more provided through-holes, and providing in the second space an alkali vapor supply part and a chip pipe part for discharging the residual alkali in the photocathode manufacturing process. The constructed photoelectric conversion tube. 2. A photocathode on the inner wall of one bottom surface of the airtight container, a mesh electrode disposed close to the photocathode, and a deep dish-shaped portion connected to the side wall of the container at the flange and facing the photocathode surface. A method for producing a photoelectric conversion tube including a support supporting a mesh electrode, the method comprising: the mesh electrode, a side outer periphery of the support in a first space on the photocathode side divided by the support, and the airtight container. An annular space formed between the inner peripheries of the supporting body is communicated with a second space inside the container through one or more through holes provided on the side surface of the support, and during the photocathode manufacturing process, from the second space side. Supplying alkali vapor to form a photocathode, and before sealing off the chip provided in the second space, remove residual alkali vapor from the first space side after forming the photocathode through the one or more through holes. A method for manufacturing a photoelectric conversion tube comprising a step of removing excess alkali through a second space.