JPH07211224A - Manufacture of cathode filament coil for x-ray tube - Google Patents

Abstract

PURPOSE:To increase the quantity of thermodelectron emission without causing cracks on a coil by keeping a proper angle between the axial direction of a core wire and the axial direction of coiling and coiling an elemental wire densely on the core wire. CONSTITUTION:The pitch 11a of a filament coil 11 in the axial direction is narrowed and a wire to be coiled is coiled densely to narrow the gap 11b between turns of the wire, and the axial direction 12 of a core wire and the axial direction of coiling are set to be at a proper angle theta. The coil 11 is thus prepared by coiling an elemental wire 42 on the core wire 41 while tilting in the axial direction 12, and the coil extended length per one pitch becomes long and the curvature becomes wide, so that no unnatural force affects the coil elemental wire 42. As a result, coil (cracking does not occur and effective thermoelectron emission surface area can be widened by making the pitch of the coiling dense and the quantity of thermoelectron emission wire 42 on the core wire 42 into is prepred by coiling the elemental wire 42 on the core wire 42 into a cylindrical shape and the coil's curvature is not altered, the size precision is heightened and the resulting coil can be used as a coil for a cathode of an X-ray tube with narrow focus and small tube current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a cathode filament coil for an X-ray tube having an increased amount of thermionic emission.

[0002]

2. Description of the Related Art As a conventional cathode filament coil for an X-ray tube, there is a filament coil 61 which is wound into a cylindrical shape by drawing a substantially perfect circle as shown in the cross section of FIG.
However, in such a filament coil 61, sufficient thermoelectron emission cannot be obtained and the electron density in the focal width direction of the target (anode) cannot be made uniform. That is, as shown in FIG. 7, the thermoelectrons 72 emitted from the filament coil 61 in the focusing electrode section 71 enter the target (anode) 73, and the electron density distribution in the focal width direction thereat is a characteristic curve 74. As shown, the uniformity is greatly impaired.

Further, in order to obtain a sufficient amount of thermionic emission in the filament coil 61, its axial pitch 6 is set.
1a may be shortened and the gap 61b between the coil windings may be narrowed, that is, tightly wound. However, if the gap 61b between the coil windings is attempted to be narrowed, the coil expansion length 61c per pitch is 61c.
(See FIG. 8) becomes short. For this reason, there is a problem in that when the coil is manufactured, a load is applied to the coil wire and a crack (break) occurs.

Therefore, the following filament coil has appeared. That is, as disclosed in Japanese Utility Model Laid-Open No. 61-127559, a filament coil is formed with a wide arc surface portion, for example, an elliptical cross section, and the long diameter surface portion is opposed to the target of the anode. Then, according to this, the amount of thermionic electrons can be increased and the electron density in the focal width direction of the target can be made uniform.

In this case, in order to form the filament coil into an elliptical shape, a method of making the core wire when wound around the filament coil into an elliptical shape, or crushing a coil formed into a cylindrical shape to deform it is employed. Was there.

[0006]

However, it is difficult to manufacture a filament coil having high dimensional accuracy with the above-mentioned conventional technique. That is, in the method of forming a coil by winding it around an elliptical core wire, the coil curvature changes, so that the coil size changes after winding. In addition, the method of crushing and deforming the coil formed in a cylindrical shape cannot essentially manufacture with high dimensional accuracy, and variations among products are likely to occur. In particular, a cathode filament coil used for a micro focus X-ray tube has a problem that higher dimensional accuracy is required and it cannot be manufactured by the above-mentioned conventional technique.

The object of the present invention is to increase the amount of thermionic emission without causing coil cracking (bending), and to make uniform the electron density in the focal width direction of the target.
Moreover, the dimensional accuracy is high and there is no variation between products,
An object of the present invention is to provide a cathode filament coil for an X-ray tube, which is also suitable as a cathode filament coil for an X-ray tube having a micro focus, and a manufacturing method thereof.

[0008]

The above-mentioned object is to use an outer circular core wire as a core wire around which an element wire is wound, and to provide an appropriate angle between the axial direction of the core wire and the winding axial direction and to make the core wire dense. Winding the wire around the core wire to form a coil, and
This is achieved by manufacturing a cathode filament coil for a wire tube.

[0009]

[Function] A cathode filament coil for an X-ray tube has an outer circular shape (cylindrical shape, cylindrical shape, etc.) as a core wire around which an element wire is wound.
The core wire is used, and the core wire is coiled by winding the element wire around the core wire so that the core wire has an appropriate angle between the axial direction of the core wire and the winding axis direction, and is dense.

According to the above-mentioned method of the present invention, the shape is formed at the time of winding the coil. However, this means that the coil is wound by applying a uniform force with a constant load, so that the coil is mechanically wound. The dimensional accuracy of the filament coil can be manufactured with high accuracy, and the dimensional accuracy can be significantly increased as compared with the method of crushing and deforming a coil formed in a cylindrical shape, and variations among products are less likely to occur. In particular, a cathode filament coil used for a micro focus X-ray tube requires higher dimensional accuracy, which can be realized by the method of the present invention.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 3A and 3B are views showing an example of a cathode filament coil for an X-ray tube according to the method of the present invention, in which FIG. 3A is a sectional view and FIG.
Is a view seen from the axial direction.

As shown in FIG. 3, the cathode filament coil for an X-ray tube according to the method of the present invention comprises a filament coil 11 inclined with respect to the axial direction 12 and densely wound with a cylindrical wire. Is.

Such a filament coil 11 has a target (anode) as compared with the conventional cathode filament coil for an X-ray tube shown in FIG. 6 (conventional filament coil 61 wound in a substantially circular shape in a cylindrical shape). The electron density in the focal width direction can be made uniform. That is, as shown in FIG. 4, the thermoelectrons 72 emitted from the filament coil 11 in the focusing electrode section 71 enter the target (anode) 73, and the electron density distribution in the focal width direction there is a characteristic curve 75. It has uniformity as shown.

Further, in order to obtain a sufficient amount of thermionic emission in the filament coil 11, its axial pitch 1
1a may be shortened and the gap 11b between the coil windings may be narrowed, that is, tightly wound. In the filament coil 11 of the present invention, the strands of wire are wound in a state of being inclined with respect to the axial direction 12, and the coil expansion length 11c per pitch (see FIG. 5) becomes long and the coil curvature becomes large. Since an unreasonable force is not applied to the coil wire, the winding pitch can be reduced without the occurrence of coil breakage (bending). Therefore, since the winding pitch can be made dense and the effective emission area of the thermoelectrons can be widened, a large number of thermoelectrons can be taken.

Further, the filament coil 11 is formed by winding a wire in a cylindrical shape, and the coil curvature does not change unlike an elliptic cylindrical coil. Therefore, changes in coil dimensions after creation (changes in coil shape due to springback)
It is also suitable as a cathode filament coil for an X-ray tube having a small focal point and a large tube current, because the dimensional accuracy is improved and a large amount of thermionic electrons can be obtained.

FIG. 1 is a diagram for explaining an embodiment of a method of manufacturing a cathode filament coil for an X-ray tube according to the present invention. In FIG. 1, 41 is a core wire, and 42 is an element wire wound around the core wire 41. In the method of the present invention,
An outer circular core wire is used as the core wire 41 around which the element wire 42 is wound, and the axial direction 43 and the winding axial direction 44 of the core wire 41 are used.
And an appropriate angle .theta. Between the core wire 41 and the core wire 41 to form a coil. here,
It is conceivable that the angle θ takes a conical shape, but an angle within 45 degrees is set. This is because if it exceeds 45 degrees, the wire 41 wound from the winding side slips and cannot be skillfully wound.

FIG. 2 is a view for explaining a concrete example of a method for manufacturing a cathode filament coil for an X-ray tube according to the present invention. In FIG. 2, 41 to 44 and θ are the same as in FIG. Reference numeral 51 is a core fixing base for fixing the core 41. Reference numeral 52 is a winding machine for winding the wire 42 around the core wire 41 fixed to the core wire fixing base 51 while paying it out.
Reference numeral 4 is a wire supply portion (a wire 42 wound around a reel) and a rotating shaft.

That is, here, the axial direction 43 of the core wire 41 is
Is inclined by an angle θ with respect to the axial direction (winding axis direction 44) of the rotary shaft 54 of the winding machine 52 that winds the strand 42 around the core 41 while winding the strand 42 around the core 41 side or the winding machine 52. The rotating shaft while moving at least one of the sides, here the core wire 41 side (core wire fixing base 51), in the direction away from the winding machine 52 side (arrow 55 direction) at a speed according to the winding pitch setting value. 54 is rotated in the direction of arrow 56 to wind the wire 42 around the core wire 41, thereby forming a coil in which the wire 42 is wound densely and densely, that is, a cathode filament coil for an X-ray tube. To manufacture.

In the winding machine 52, when the rotating shaft 54 rotates, the wire 42 is fed from the wire supply portion 53 with an appropriate tension (back tension), and the wire 42 has a constant load. Force is applied almost uniformly with the core wire 4
Wrapped around 1. Further, on the core wire fixing base 51 side, an angle adjusting mechanism (not shown) is provided so that the angle θ can be changed depending on the material and cross-sectional shape of the wire 42.

In the example shown in FIG. 2, the axial direction 43 of the core wire 41 is
In the axial direction of the rotary shaft 54 of the winding machine 52 (winding axial direction 4
4) Inclination with respect to 4) (when the winding axial direction 44 is horizontal) is shown, but conversely, the winding machine 5
The axial direction of the second rotary shaft 54 (winding axial direction 44) may be inclined with respect to the axial direction 43 of the core wire 41 (the axial direction 43 of the core wire 41 is horizontal).

According to the present invention, the diameter of the wire 42 and the core wire 41
It was possible to obtain a micro focus cathode filament coil for an X-ray tube having a high dimensional accuracy and a wide effective emission area of thermoelectrons even when the diameter of the cathode was small and was about 0.1 to 0.2 mm.

[0022]

As described above, according to the present invention, the amount of thermionic emission can be increased without causing coil cracks (breakage), and the electron density in the focal width direction of the target can be made uniform. In addition, the dimensional accuracy is high, there is no variation between products, and there is an effect that it is possible to provide a method for manufacturing a cathode filament coil for an X-ray tube, which is suitable as a cathode filament coil for an X-ray tube having a fine focus.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of a method for manufacturing a cathode filament coil for an X-ray tube according to the present invention.

FIG. 2 is an explanatory view of a specific example of a method for manufacturing a cathode filament coil for an X-ray tube according to the present invention.

FIG. 3 is a diagram showing an example of a cathode filament coil for an X-ray tube according to the method of the present invention.

FIG. 4 is a diagram showing a state of electron emission and a current density distribution when the same filament coil is used.

FIG. 5 is a diagram showing a developed length of an element wire per pitch of the filament coil of the same.

FIG. 6 is a sectional view showing a conventional cathode filament coil for an X-ray tube.

FIG. 7 is a diagram showing a state of electron emission and a current density distribution when a conventional filament coil is used.

FIG. 8 is a diagram showing a developed length of an element wire per coil pitch of a conventional filament coil.

[Explanation of symbols]

11 Filament coil of the present invention 61 Conventional filament coil 11a, 61a Axial pitch 11b, 61b Gap between coil windings 11c, 61c Coil expansion length per pitch 12 Filament coil axial direction 41 Core wire 42 Wire (coil wire) ) 43 core axial direction 44 winding axial direction (axial direction of winding machine rotating shaft) θ angle formed between core axial direction and winding axial direction 51 core wire fixing base 52 winding machine 53 wire supply of winding machine Part 54 Rotating shaft of winding machine 71 Focusing electrode part 72 Thermoelectron 73 Anode part 74 Electron density distribution characteristic curve by conventional filament coil 75 Electron density distribution characteristic curve by filament coil of the present invention

Claims (1)

[Claims] 1. A core wire having a circular outer shape is used as a core wire around which the wire is wound, and the core wire is made dense by allowing an appropriate angle between the axial direction of the core wire and the winding axial direction. A method for manufacturing a cathode filament coil for an X-ray tube, which comprises winding and forming a coil.