JPH01241797A - Anode rotary driving device of x-ray tube - Google Patents

Abstract

PURPOSE:To prevent generation of needless heat while supplying no needless electric power by providing a means to detect a state of series resonance with a fixed coil and a phase advancing capacitor for stopping or reducing supply of AC power. CONSTITUTION:While output of an inverter circuit 1 is constant, equivalent impedance of a coil 4 changes with a rise of rotation of an anode, a phase advancing capacitor 5 and a coil 4 get to a state of resonance of series and impedance of a split-phase circuit lowers so that a split-phase current rises from a to b1. And reaching the upper limit of rotation, current rise also stops. In this case, a control circuit 7 detects output of a current detector 6 for obtaining a signal of an envelope a b1 so a to compare with an optional set-point, or detects a point of losing a change, or detects a b1 point by both of these in order to stop or reduce output of the inverter 1. Thereby, power over need is not supplied to a fixed coil so as to generate no needless heat.

Description

[Detailed description of the invention] [Object of the invention] (Field of use in Pi industry) The present invention provides a drive for rotating the anode of an X-ray tube (rotating anode X-ray tube) installed in an X-ray diagnostic device, etc. Attire! In particular, the present invention relates to an anode rotation drive device for an X-ray tube that can suppress unnecessary heat generation.

(Prior Art) A rotating anode X-ray tube (hereinafter simply referred to as "X-ray tube") is a device that can obtain a large amount of X-rays by rotating the anode and dispersing the heat generated at the anode. be.

Specifically, a rotor, similar to that of a typical motor, is attached to the anode in the vacuum of an X-ray tube, and two coils are wound around the outside of the vacuum wall to form a stator. The anode, which is integrated with the rotor, is rotated by supplying currents with different phases to generate a rotating magnetic field.

What supplies current to this coil is the X-ray tube's anode rotation drive! It is generally called an X-ray tube starter.

In this way, this rotary drive device is in principle the same as the general induction motor TA, but as mentioned above, it is inefficient because it rotates the rotor in a vacuum, and it is It is sufficient to rotate only when generating X
It supplies the coil of the wire tube.

On the other hand, when no X-rays are generated, braking power is also supplied to keep the anode rotating at a low speed or stationary in order to prevent mechanical stress caused by high-speed rotation of the anode. For this reason, the temperature rise in the X-ray tube restricts its continuous use and affects the life of the X-ray tube.This heat generation is due to the heat generated by the X-ray tube itself It is so large that it is about the same size.

By the way, the power required to rotate this anode varies greatly depending on whether you start it up from a stationary state or from a state where it is rotating even slightly, and it also depends on the individual X-ray tube. Not only are they different, but they also change over time even within the same X-ray tube.

Therefore, in the past, a large amount of power was supplied to rotate the anodes of all normal X-ray tubes from a stationary state, so in most cases, more power was supplied than necessary, and even a small amount of rotation was required. In this case, there is a problem in that a considerable amount of extra power is supplied and heat generation becomes large as described above.

(Problems to be Solved by the Invention) As described above, in the conventional technology, more power than necessary is supplied to the stator coil, resulting in the problem of heat generation.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an anode rotation drive device for an X-ray tube that prevents generation of unnecessary heat as much as possible without supplying unnecessary power.

[Structure of the Invention] (Means for Solving the Problems) The present invention has a structure in which the following means are taken to solve the above problems and achieve the objects.

That is, the present invention provides an anode rotation drive device for an X-ray tube that supplies alternating current power to a stator coil and a phase advance capacitor to rotationally drive the anode of an X-ray tube, in which the stator coil and the phase advance capacitor are connected in series. The present invention is characterized by providing means for detecting a state of resonance and stopping or reducing the supply of the AC power based on the detection.

(Function) According to such a configuration, when the stator coil and the phase advance capacitor are in a state of series resonance, it is indirectly indicated that the rotation of the anode has reached the upper limit, so the detection of the state of series resonance can be used to detect the rotation of the anode. By stopping or reducing the supply of AC power, the stator coils are not supplied with more power than necessary, and therefore,
No unnecessary heat is generated.

(Example) The anode rotation drive device for an X-ray tube according to the present invention will be described below with reference to FIG. In FIG. 1, 1 is an inverter circuit that supplies an AC output of an arbitrary frequency to an X-ray tube 2;
and 4 are two coils of the stator that generate a rotating magnetic field that rotates the anode of the X-ray tube, 5 is a phase advancing capacitor for supplying the phase-split output to coil 4, and 6 is the phase-split output. 7 is a control circuit that measures the signal sent from the current detector and outputs a signal to stop the output of the inverter circuit 1.

With the above configuration, the waveform of the current detector 6 will be shown and its operation will be explained with reference to FIG.

FIG. 2(a) shows a case where the anode of the X-ray tube 2 starts rotating from a stopped state. Although the output of the inverter circuit 1 is constant, the equivalent impedance of the coil 4 changes as the rotation of the anode increases. Then, the phase advancing capacitor 5 and the coil 4 enter a series resonance state, the impedance of the phase splitting circuit decreases, and the current of the splitting phase increases from a to bl, and when the rotation reaches the upper limit, the current increases. In the conventional case, the inverter circuit 1 would have transitioned from bl to C, and at C after a specified time had elapsed, the inverter circuit 1 would have stopped or reduced its output.

In this way, by observing the current of this phase-split output, it is possible to indirectly know that the rotation of the anode has reached the upper limit.

In the past, where this was not possible, extra power was supplied from bl to C as described above. However, the control circuit 7 detects the output of the current detector 6 and changes a→b1.
The b1 point is detected and the output of inverter 1 is stopped or reduced by obtaining the envelope line signal and comparing it with an arbitrary set value, or by detecting the point where there is no change, or both. .

This arbitrary set value may be determined in advance or automatically determined after detecting the value of the -degree C point.

In addition, if the current changes over time due to temperature, etc., the current value is detected at point C at a specified time without interrupting the output, and this value is automatically updated to the new set value. That will make it more certain.

To describe one embodiment, this control circuit 7 is composed of a full-wave rectifier circuit, an A/D converter, and a CPU.
The b1 point can be determined by reading the phase-separating circuit current using an A/D converter, comparing the value with a set value, and calculating the amount of change.

Figure 2 (b) shows the result when the anode of the X-ray tube 2 is rotated even slightly and the rotation is raised to the upper limit. According to this example, the extra output from b2 to C is can be stopped.

According to this embodiment, the output of the inverter circuit 1 is stopped when the rotation reaches the upper limit, regardless of individual variations in the X-ray tube 2 or whether or not it is already rotating to some extent at the time of startup. Therefore, the anode rotation can be controlled with the minimum amount of power required.

In addition, when generating X-rays for a long time, conventionally a small amount of power was continuously supplied compared to when starting up the rotation, but over a long period of time, the heat loss was the same as when starting up. was given to the X-ray tube.

According to this embodiment, there is no need to continuously supply power at this time, and it is possible to perform control such that power is intermittently supplied only when the rotation of the anode reaches the upper limit.

As described above, according to this embodiment, it is possible to reduce the heat generation of the X-ray tube, reduce the restrictions on the use of the X-ray tube due to heat generation, and improve the efficiency of X-ray diagnosis. This has the advantage that the life of the wire tube can also be extended.

The present invention is not limited to the above-mentioned embodiments, and the means for detecting that the rotation of the anode has reached the upper limit can be simply by detecting the state of series resonance, and by simply detecting the current in the phase splitting circuit. Instead, similar results can be obtained by detecting the voltage across the phase advancing capacitor or the voltage across the coil 4.

The present invention is not limited to the above embodiments, but can be implemented with various modifications without departing from the gist of the present invention.

[Effects of the Invention] As described above, in the present invention, the stator coil and the phase advance capacitor are provided with means for detecting the state of series resonance and stopping or reducing the supply of AC power based on the detection. When the phase advance capacitor is in series resonance state, this indirectly indicates that the rotation of the anode has reached the upper limit. Therefore, by stopping or reducing the supply of AC power by detecting the series resonance state, No more power is supplied than necessary, and therefore no unnecessary heat is generated.

Therefore, according to the present invention, it is possible to provide an anode rotation drive device for an X-ray tube that prevents generation of unnecessary heat as much as possible without supplying unnecessary power.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of an anode rotation drive device for an X-ray tube according to the present invention, and FIG. 2 is a waveform diagram showing the operation of the embodiment. 1...Inverter circuit, 2...X! I tube, 3.4・
... Stator coil, 5... Phase advance capacitor, 6...
Current detector, 7... control circuit. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] In an anode rotation drive device for an X-ray tube that supplies alternating current power to a stator coil and a phase advance capacitor to rotationally drive an anode of the X-ray tube, the stator coil and the phase advance capacitor detect a state of series resonance. An anode rotation drive device for an X-ray tube, comprising means for stopping or reducing the supply of alternating current power based on the detection.