JPH054800B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a drive device for rotating an anode of an X-ray tube (rotating anode X-ray tube) installed in an X-ray diagnostic device, etc. 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) Rotating anode X-ray tube (hereinafter simply referred to as "X-ray tube")
In this method, a large amount of X-rays can be obtained by rotating the anode and dispersing the heat generated at the anode.

Specifically, a rotor, similar to 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.
Currents with different phases are supplied to these two coils to generate a rotating magnetic field, which rotates the anode that is integrated with the rotor.

The device that supplies current to this coil is the anode rotation drive device of the X-ray tube, which is generally called the starter of the X-ray tube.

In this way, this rotary drive device is in principle the same as the power source for a general induction motor, but as mentioned above, it is ineffective because it rotates the rotor in a vacuum, and it is It is sufficient for the X-ray to rotate only when generating the It supplies the tube coil.

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

By the way, the electric power required to rotate the anode differs greatly between starting it from a stationary state and starting it from a state where it is rotating even slightly. Moreover, it not only differs depending on the individual X-ray tube, but also changes over time even within the same X-ray tube.

Therefore, in the past, large amounts of power were supplied to rotate the anodes of all normal X-ray tubes from a stationary state. In this case, there is a problem in that a considerable amount of extra power is supplied and the heat generation becomes large as described above.

(Problem to be solved by the invention) In this way, in the conventional technology, more power is supplied to the stator coil than necessary,
There was a problem with heat generation.

Therefore, the purpose of the present invention is to prevent the generation of unnecessary heat as much as possible without supplying unnecessary power.
An object of the present invention is to provide an anode rotation drive device for a wire tube.

[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 advancing capacitor are in a state of series resonance, it indirectly indicates that the rotation of the anode has reached the upper limit.
By stopping or reducing the supply of AC power by detecting the state of series resonance, no more power than necessary is supplied to the stator coil, 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 Figure 1,
1 is an inverter circuit that supplies an AC output of an arbitrary frequency to the X-ray tube 2; 3 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 an output that outputs to the coil 4. A phase advance capacitor for supplying phase-split signals, 6 a current detector that detects the current of the phase-split output, and 7 a current detector that measures the signal sent from the current detector and detects the output of the inverter circuit 1. This is a control circuit that outputs a stop signal.

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

FIG. 2a 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 phase splitting current increases from a to _b1 . Then, when the rotation reaches the upper limit, the current increase stops, and in the conventional case, the inverter circuit 1 changes from b ₁ to c, and at c, when a specified time has elapsed, the inverter circuit 1 stops or reduces 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 its upper limit.

In the past, where this was not possible, extra power was supplied from _b1 to c as described above. However, the control circuit 7 detects the output of the current detector 6 to obtain an envelope signal of a → b ₁ , and compares it with an arbitrary set value, or detects a point where there is no change, or With both of these, point _b1 is detected and the output of the inverter 1 is stopped or reduced.

This arbitrary set value may be determined in advance, or may be determined automatically after the value of point c is detected once.
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 set to the new set value. It will be more reliable if you update to .

To describe one embodiment, this control circuit 7 is as follows:
It consists of a full-wave rectifier circuit, an A/D converter, and a CPU, and the CPU reads the phase-dividing circuit current using the A/D converter, compares the value with the set value, and calculates the change. And b ₁ point can be known.

Figure 2b 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 b ₂ to c is It can be stopped.

According to this embodiment, the output of the inverter circuit 1 can be 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 to the X-ray tube was about the same as when it was started up. 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 its 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-ray tube, 3, 4
...Stator coil, 5... Phase advance capacitor, 6...
...Current detector, 7...Control circuit.

Claims (1)

[Scope of Claims] 1.
In a wire tube anode rotation drive device, a means for measuring the current flowing through the phase advancing capacitor, a means for detecting a state of series resonance between the stator coil and the phase advancing capacitor from a measurement value by this means, and this means. An anode rotation drive device for an X-ray tube, comprising: means for reducing the supply of alternating current power in accordance with the state of series resonance detected by.