JPH0637600Y2 - X-ray tube filament heating circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an X-ray tube heating circuit, and more particularly to a circuit for heating an X-ray tube filament by a current control method in an X-ray high voltage apparatus.

[Prior Art] In the conventional example, as shown in FIG. 2, a switching regulator 4 and an inverter 7 are connected to the primary side of a heating transformer 8, and a tube current is set by a setter 12. It

As described above, the current control type X-ray tube filament heating circuit is a combination of a switching regulator and an inverter.

This is to control the output voltage of the switching regulator so that the current flowing through the heating circuit becomes equal to the set value.

Conventionally, the current flowing in the heating circuit is detected to protect against overcurrent.

[Problems to be solved by the invention] However, since the switching regulator is used, the output side of the heating circuit, that is, the arm of the inverter unit, the primary and secondary sides of the heating transformer, or the X-ray. Even if one of the filaments of the tube is short-circuited, the output voltage is controlled so that the detected current becomes equal to the set value.

That is, there is a problem in that an abnormality such as a circuit short circuit is not detected.

An object of the present invention is to detect a circuit abnormality by detecting a short circuit in any one of an arm of an inverter, a primary side and a secondary side of a heating transformer, or a filament of an X-ray tube in a current control type. At the same time, it is possible to prevent high voltage from being applied to the X-ray tube when the filament is not ignited.
An object of the present invention is to provide a wire filament heating circuit.

[Means for Solving the Problems] The above-mentioned object is to provide an output voltage detection circuit for a switching regulator in a current control type X-ray tube filament heating circuit in which a switching regulator and an inverter are combined on the primary side of a heating transformer. And a circuit for detecting a short circuit in the X-ray tube filament heating circuit from the detected voltage.

[Operation] The output voltage of the switching regulator is constantly detected, the detected voltage is compared with the reference voltage, and the resulting signal is used as a control signal for the switching regulator, the inverter, and the X-ray controller. Sent.

[Embodiment] A preferred embodiment of the present invention will be described with reference to FIG.

For convenience of comparison, FIG. 2 showing a conventional example will be described.

Heating current control signal V3 from tube current setting device 12 and detection resistor
The output voltage V1 of the switching regulator 4 is controlled so that the voltage V2 generated by the primary current I1 flowing to 10 becomes equal. As a result, the heating current I2 of the filament of the X-ray tube 9 is controlled.

At this time, if any of the arm of the inverter 7, the primary side and the secondary side of the heating transformer 8 or the filament of the X-ray tube 9 is short-circuited, the notching regulator 4 causes the voltage V2, That is, the output voltage V1 is lowered so that the current I1 flowing through the detection resistor 10 becomes equal to the set voltage V3.

At this time, no heating current flows through the filament. That is, there is a possibility that an abnormality such as a short circuit of the output cannot be detected, and the filament may apply a high voltage to the X-ray tube in a non-ignition state.

1 is an AC power source, 2 is a rectifier, 3 and 5 and 6 are capacitors, and 11 is a control circuit.

In one embodiment of the present invention shown in FIG. 1, the output voltage V1 'of the switching regulator 4, that is, the voltage V4 divided by the voltage dividing resistors 15 and 16 is set according to the type of the X-ray tube. It is almost decided by the generated tube current. Therefore, a reference voltage generator 14 is used, which generates a voltage V5 corresponding to the divided voltage V4 from the X-ray tube type and the set tube current.

Here, if a short circuit occurs in any of the arm of the inverter 7, the primary and secondary sides of the heating transformer 8 or the filament of the X-ray tube 9, the output voltage V1 ′ of the switching regulator 4 is generated. Is abnormally low. That is, the divided voltage V4 becomes abnormally low.

Therefore, for example, 1 / of the preset value of voltage V5
The value of 2 and the value of the divided voltage V4 are compared by the comparison circuit 13,
If the divided voltage V4 is lower, in terms of the deviation mentioned above,
It can be determined that a short circuit has occurred, and this is transmitted to the switching regulator 4, the inverter 7 and the X-ray controller (not shown).

The reference voltage V5 may be a constant value that represents all the X-ray tubes and the tube current without changing according to the type of the X-ray tube and the tube current.

[Effect] According to the present invention, by detecting the output voltage of the switching regulator, it is possible to detect an abnormality such as a short circuit, and when the operation of the switching regulator and the inverter 7 connected thereto is stopped. At the same time, the comparison circuit generates a signal for stopping the application of high voltage. By doing so, it is also possible to prevent the high voltage from being applied in the filament non-ignition state, which occurs when the circuit is short-circuited.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, and FIG. 2 is a conventional circuit diagram. 4 is a switching regulator, 7 is an inverter, 8 is a heating transformer, 13 is a comparison circuit, 14 is a reference voltage generator, and 15 is a reference voltage generator.
And 16 are resistors for voltage division, V4 is a divided voltage, and V5 is a reference voltage.

Claims (1)

[Scope of utility model registration request] 1. An X-ray tube filament heating circuit of a current control system in which a switching regulator and an inverter are combined on the primary side of a heating transformer, and an output voltage detection circuit of the switching regulator and an X-ray tube filament from the detected voltage. An X-ray tube filament heating circuit, comprising: a circuit for detecting a short circuit in the heating circuit.