DE8436129U1 - X-ray image intensifier - Google Patents

Description

Siemens Aktiengesellschaft Our mark
Berlin and Munich VPA 8Ί P 3 4 9 9 QB

X-ray image intensifier

The invention relates to the X-ray image intensifier
Preamble of claim 1. Such image intensifiers
are known from US-PS 34 58 744.
10

In the case of electronic image intensifiers, the aforementioned

C patent mentioned type, as is known, X-ray images are converted into electron images, which are then a
Accelerating voltage suspended and possibly | electron-optically reduced on an output screen '■ are mapped. In the case of X-ray image intensifiers, which are usually designed in one stage, if the electron image is imaged in a reduced size, this is on the
The image that appears in the home screen is also the one that

is looked at. However, this presupposes that the output screen can be seen through the wall of the piston of the image intensifier. It was therefore ί, at least at this point, made the piston from transparent material, especially glass. i

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In order to find an expediently manageable constructive solution

received, one has the window J inserted into the flask

at the same time to the carrier of the exit luminescent screen i ¹

power. Since in the known constructive solution the \

Exit window by melting it into a metal frame |

men can only be taken after this activity of the |

Luminescent screen are applied. But this is after- |

part, because when coated with the luminescent layer g

the yield of screens that can be used later is low, so f

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that the precisely to be carried out connection of the glass pane with the frame must be made in very many cases on panes which later only lead to unusable screens.
5

The invention is based on the object of an X-ray image intensifier of the type mentioned at the beginning, in which the finished output screen is used as the output window taken in a metal frame and inserted into the wall of the vacuum flask. This task

, is used in an image intensifier according to the generic term of

Claim 1 achieved by the features mentioned in its characterization. Appropriate further training and developments are objects of the subclaims. 15th

By using a soft solder to solder the window pane into a metal frame, which by means of a Flange can be inserted into the window opening of the vacuum flask of an image intensifier, i.e. a solder whose Melting temperature is between 250 and 400 ° C, on the one hand at the lowest possible temperature on the other hand the soldering that can withstand the baking of the image intensifier. It is used to protect the fluorescent screen

(expediently carried out in an inert medium

by soldering in a hydrogen atmosphere or in another protective gas or in a vacuum. In this case, the light yield of the luminous layer that can be achieved during later operation of the image intensifier is not yet impaired.
30th

For the metal frame, see the manufacturing and operating conditions Resistant metals suitable, which work with the material of the exit window as well as with the one of the tubular piston are tightly connectable. For use in glass flasks, those have proven that

ζ as main components nickel (Ni), iron (Fe) or

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Ni, chromium (Cr), Fe or Ni, cobalt (Co), Fe or Ni, Co, Cr, Fe. It's iron alloys that! contain between 20 and 60 % Ni and / or 10 to 30 %

Co and / or 1 to 10 % Cr.
5

Solders based on lead (Pb) have proven successful for soldering. These plumb bobs have opposite others have the advantage that their processing temperature, including their re-softening, is well above the temperature is necessary for the degassing heating of the x "image intensifier tube in the course of manufacture «Ι- is. However, it is still below one for the luminous

■ ability of the luminous pigment harmful temperature.

In addition to lead, alloys have proven useful in which

Lead alloyed with silver (Ag), tin (Sn) and indium (in) is. The additives are approximately in amounts ranging from 0.1 percent by weight to 10 percent by weight, the Lead added, on the one hand to achieve an effect of the additive with small amounts and on the other hand in the case of large quantities added, this does not result in an increased melting temperature and the formation of which makes the soldering more difficult having to accept material inhomogeneities. An alloy of lead and 2.5 has proven to be favorable Proven weight percent silver.

The wetting and adhesion of the solder to the parts to be connected can be achieved by adapting their surfaces, for example by simply coating or covering with a system of layers made of coordinated materials be promoted. A simple adhesive layer or the first layer of a suitable layer sequence For glass, it should consist of a substance that has a high affinity for oxygen, as the connection to the Glass surface is made over metal oxide. As well as

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the metal of the coating as well as the oxide formed at the boundary must for the desired attachment have sufficient tensile strength.

The second layer is a protective layer for the first layer and can also be a solder layer. The second Layer must stop the flow of solder in such a way that it does not separate from the first.

10 The third layer protects the first two from Oxi-ν dation and can also be a solder layer.

Suitable materials are for the

1st layer: titanium (Ti), niobium (Nb), tantalum (Ta), NiCr, Cr, Fe,

2nd layer: Ni, gold (Au), platinum (Pt), molybdenum (Mo),

Fe and for the

3rd layer: Au, silver (Ag), Ni, copper (Cu), Pt,

Palladium (Pd).
20th

Suitable systems coordinated layers may consist of layer sequences, for example, for the Anlötung a glass sheet in which the glass Zuer £ \, f) chromium is vapor-deposited in a thickness of 30 nm to 300 bar. If this layer is deposited under high vacuum, it can be assumed that the metallic chromium in the vapor phase and on the glass surface will react with oxygen or with thin oxide coatings. The actual adhesion t thus arises via a very thin

\ 30 Settlement of a chromium oxide layer that cannot be defined in more detail. This first layer can then be followed by a second layer of nickel and then a third layer of silver, the thickness of which is the same

f§ correspond to chrome.

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The chromium layer can also be coated with iron, which is coated with nickel and then on the one Nickel-silver alloy follows, or it becomes an iron-chromium-nickel alloy or a chromium-nickel alloy vaporized. When layering, it is only necessary to ensure that the layers closest to the glass are in the order Chromium oxide-chromium are built up, a layer of at least 30 / µm thick consists of pure chromium, since this does not form solid solutions with lead, and that the top layer consists of nickel or Ag, because there is good solubility of lead in these and therefore good bonding ability with the solder. In the end the entire layer which improves the adhesion can be covered with gold. This causes when sufficient Tightness, which can be achieved at thicknesses of about 400 mm, so that oxidation of the top layer, i.e. the formation of nickel or silver oxide, for example, is avoided.

The metal frame can also be coated with the above-mentioned adhesive layers or on the surfaces to be soldered. Layering be provided. Especially when using Niromed 44 or Vacon 20 or Vacon 70 as frame material the solder will adhere well to this part as well. The actual soldering is preferably carried out in a high vacuum with layer thicknesses of 100 to 300 mn per individual layer. Soldering takes place at temperatures around 350 ° C and instead of the high vacuum, a protective gas atmosphere can be used, for example one from Hydrogen.

Further details and advantages of the invention are illustrated below with reference to the figures Embodiments further explained.

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In the figure 1 is the cross section through a

schematically shown single-stage vacuum X-ray image intensifier drawn,
5

FIG. 2 shows a section of the connection between the exit window and the electronic one Image intensifier vacuum flask and 10

FIGS. 3 to 5 show different embodiments of adhesive layers on the exit window .

In FIG. 1, 1 is the vacuum bulb of an X-ray image intensifier designated. This piston 1 consists of a cathode cap 2, which has an opening of a a tube of graduated diameter representing ceramic body 3 closes, the other opposite to the first opening having a smaller diameter is closed by an anode attachment 4. Inside the Piston 1 is the per se known structure of an electronic image intensifier, i.e. on the inner wall the cap 2 opposite the extension 4 is a luminescent layer 5, which is covered with a photocathode layer 6 is covered. Then follow electron-optical electrodes 7 and 8, which are attached to the ceramic body 3, and finally the actual anode 9. To close the outward opening of the anode 9 is means a soldering 10, the disc 12 lying on the frame 11 of the exit window. The disc 12 carries the fluorescent exit screen 13 on its inside and is connected to the frame 11 in a vacuum-tight manner by a soldering point 14.

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The operation of the image intensifier is known to be based on the fact that through the wall of the cap 2 in the Luminous layer 5 penetrating x-ray images in the photocathode 6 trigger an electron image. This will then imaged by means of the electrodes 7 and 8 and the anode 9 on the luminous layer 13 by the corresponding Potentials to the cap 2, the connecting lines 16 and 16, to the electrodes 7 and 8 and to the extension 4 for the anode 9 are applied.

From Figure 2 it can be seen that the soldering point 14 between the disk 12 and the inside of the frame 11 consists of adhesive layers 20 of the disc 12 and 21 of the frame 11, which are through the actual solder layer 22 are connected to each other. The latter consists of an alloy product of lead with 2.5 percent by weight Silver and is 0.05 to 1 mm thick. Layers 20 and 21 represent double layers, those which are designated by 23 and 24 in FIG. 3. The layer 23 is made of nickel and is about 200 / µm thick. The layer 24 consists of a vapor deposition layer made of chromium and is at least 30 μm thick.

The layers 20 and 21 can, however, also be made up of three layers 25, 26 and 27 in accordance with the figure. In this embodiment, you will be directed to the output window 12.1, which corresponds to the window 12 of FIG. vapor-deposited by first the layer 25 consisting of chromium or chromium oxides and at least 30 μm thick, then the at least 30 / um thick layer 26 made of nickel and finally the one made of silver and about 200 / um thick layer 27 are vapor-deposited.

In the case of a four-fold layering of the adhesive layer according to FIG. 5, in which the pane of the exit window with 12.2, a layer 28 is first made

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Chromium / chromium oxide is vaporized at least 30 μm thick on the edge of the window pane 12.2 to be soldered. This is followed by a vapor deposition layer 29 made of nickel and is 100 µm to 300 µm thick. One now The following layer 30 made of silver is then evaporated to a depth of approx. 200 μm and finally one made of gold covering layer 31.

Because soft solder is used, the disk can be detached again from piston 1 of the image intensifier. _Λ This is done by de-soldering of the frame 11. Then,), the disk used as the substrate of the luminescent layer 13 12 recovered easily and to be re-worked. This is a decisive advantage, especially when using fine optical panes, compared to soldering with glass solder, which can only be solved at temperatures above 600 ° C. While soft solder is easy to remove, a disc soldered with glass always has residues of glass solder at the soldering points after the soldering has been loosened, which can only be removed by grinding.

10 claims
5 figures

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Claims (10)

III 11 (1 - 9 - VPA 84 P 3 4 9 9 DE claims 1. X-ray image intensifier, the output window of which is in a metal frame is inserted into the tubular flask, characterized in that that the window pane is soldered into the frame using soft solder. 2. X-ray image intensifier according to claim 1, d a d u r ch marked that the solder is a lead alloy, such as one that contains lead, tin and indium. 3. X-ray image intensifier according to claim 1, characterized in that the solder consists of lead, 2.5 percent by weight of silver is added. 4. X-ray image intensifier according to claim 1, d a d u r ch characterized in that the surface of the window pane at the points where the soldering takes place, so-called adhesive layers. 5. X-ray image intensifier according to claim 4, d a d u r ch characterized in that the adhesive layers in Are applied in the form of a layer sequence, with chrome in a thickness of at least 30 μm on the glass this nickel is applied to a thickness of approx. 200 μm and silver is applied to it in a thickness of 100 to 400 μm is. 30th 6. X-ray image intensifier according to claim 4, d a d u r ch ' characterized in that the adhesive layers represent a sequence of layers whose applied to the glass Layer consists of chromium and is 3 / µm thick and that on top of the chromium layer there is a layer of iron, on it a layer of nickel and on top of this a layer of silver are applied. "9 f r m t r r m - 10 - VPA 84 P 3 4 3 9QE 7. X-ray tiildver stronger according to claim 5, d a d u r ch characterized in that the adhesive layers are provided with a cover made of gold. 8. X-ray image intensifier according to claim 1, d a d u r ch characterized in that the soldering surface of the frame is also provided with adhesive layers. 9. X-ray amplifier according to claim 8, d a d u r ch characterized in that the top layer of the adhesive layer of the frame with the top layer the adhesive layer of the window pane matches. 10. X-ray image intensifier according to claim 1, d a d u r ch characterized in that the window pane the luminescent layer of the output screen of the image intensifier supporting substrate is.