JP3216355B2 - Image intensifier device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image intensifier (hereinafter also referred to as "II device"), and more particularly to a technique for preventing magnetic distortion of an output visible light image due to terrestrial magnetism.

[0002]

2. Description of the Related Art This type of I.D. As shown in FIG. 5, the I device has a C output device for outputting a photoelectron image corresponding to the incident X-ray image.
an input surface substrate 1 including a phosphor screen such as sI and a photocathode;
An electron lens system composed of a focus electrode 2 and an anode 3 for reducing and forming a photoelectron image emitted from the photocathode of the input surface substrate 1 and electrons reduced and formed by the action of the electron lens system. An output fluorescent screen 4 for converting an image into a visible light image and outputting the converted image is housed in a tube container 5. In the figure, reference numeral 8 indicates a focus power supply, and reference numeral 9 indicates an anode power supply.

[0003] Such I. In order to avoid the influence of geomagnetism, the device I has a ferromagnetic metal
(For example, permalloy)
When the X-ray incident surface (the front surface of the input surface substrate 1) is magnetically shielded with a ferromagnetic metal 6, the incident X-rays are absorbed by the metal 6, and the X-ray dose incident on the input surface substrate 1 is reduced.
Since the finally obtained X-ray transmission image is unclear and unfavorable, a window 7 made of aluminum, titanium, glass or the like had to be formed on the X-ray incidence surface.

Therefore, photoelectrons emitted from the input surface substrate 1 are distorted by Lorentz force due to the influence of geomagnetism entering from the window 7 and the input surface substrate 1, and a visible light image output from the output fluorescent surface 4 is formed. There was a problem that it became distorted.

Conventionally, in order to eliminate the distortion of the visible light image due to the terrestrial magnetism, an I.P.M. provided with a magnetic distortion correction mechanism for interrupting terrestrial magnetism entering from the input surface substrate 1 has been proposed.
There is also an I device.

The configuration of this type of apparatus will be described with reference to FIG. FIG. 6 is a diagram showing a schematic configuration of a magnetostriction correction mechanism provided in a conventional apparatus as viewed from an X-ray incident direction.

As shown in the figure, a correction coil 10 is wound around the outer periphery of the input surface substrate 1, and a power supply 11 for supplying a current to the correction coil 10 is also provided. That is, when a current is supplied from the power supply 11 to the correction coil 10, a magnetic field is generated by the correction coil 10, and the magnetic field acts to cancel the terrestrial magnetism entering from the input surface substrate 1. Therefore, the amount of current supplied from the power supply 11 to the correction coil 10 so that the direction and the size of the magnetic field generated by the correction coil 11 can be adjusted in accordance with the direction and the size of the terrestrial magnetism entering from the input surface substrate 1 And the direction of the current can be variably set by the operator.

[0008]

However, the prior art having such a structure has the following problems. I. The I device is usually mounted on the end of the C-arm, facing the X-ray tube, and the X-ray tube and the I.I. The X-ray tube and the I.D. X-ray fluoroscopic images are obtained from various directions while changing the positional relationship of the I device. That is, I. The I device is not always fixed at a specific position, but is oriented in various directions according to shooting conditions. I. The direction and magnitude of the terrestrial magnetism entering from the input surface substrate 1 of the I device Since the direction changes depending on the direction of the I device, the operator supplies the correction coil 10 from the power supply 11 to adjust the direction and magnitude of the magnetic field generated from the correction coil 10 so as to cancel the terrestrial magnetism according to the change. The amount of current and the direction of the current must be adjusted.

However, I. Even if the direction of the I device is the same, due to the geographical conditions where the C-arm is installed,
The direction and magnitude of the terrestrial magnetism entering from the input surface substrate 1 are not always the same, and since the magnetism is not visible, the terrestrial magnetism entering from the input surface substrate 1 should be canceled by the correction coil 10. In addition, it is difficult to adjust the amount of current supplied to the correction coil 10 and the direction of the current. In addition, as described above, every time the shooting conditions change, I.P. The direction of the I device is changed, and each time the correction coil 1
There is also a problem that the amount of current supplied to 0 and the direction of the current must be adjusted, which is troublesome.

The present invention has been made in view of such circumstances, and is capable of automatically canceling out the terrestrial magnetism entering from the input surface substrate regardless of the direction of the image intensifier device. It is an object to provide a tensifier device.

[0011]

The present invention has the following configuration to achieve the above object. That is, the present invention provides an input surface substrate for outputting a photoelectron image corresponding to an incident X-ray image, an electron lens system for reducing and forming the photoelectron image, and an electronic image reduced and formed by the electron lens system. In an image intensifier device in which an output phosphor screen for converting and outputting an optical image is accommodated in a tube container, a magnetic sensor, a correction coil wound around an outer peripheral space of the input surface substrate, and a current supplied to the correction coil And a control unit that controls the power supply so as to supply the correction coil with a current that causes the correction coil to generate a magnetic field that cancels the magnetism detected by the magnetic sensor, and the correction coil Are arranged in an input surface substrate region formed between two virtual vertical planes sandwiching the input surface substrate in the optical axis direction, and the magnetic sensor is arranged in an area around the axis of the tube container. A is, yet, the gap area which is an area located between the correction coil and the input surface substrate, in which arranged in overlapping region of said input surface substrate region.

[0012]

The operation of the present invention is as follows. Since the correction coil is disposed in the input surface substrate region formed between the vertical planes sandwiching the input surface substrate, it is possible to prevent geomagnetism from entering the image intensifier device behind the input surface substrate. . In addition, since the magnetic sensor is arranged in the gap region between the input surface substrate and the correction coil and in the input surface substrate region, the magnetic sensor detects the terrestrial magnetism (direction and magnitude) entering from the input surface substrate. Detection can be performed as accurately as possible.

In such an arrangement, the magnetic sensor is
The magnetism (the direction and magnitude of the terrestrial magnetism) entering from the input surface substrate is detected, and the detection result is provided to the control means. The control means controls the power supply so as to supply the correction coil with a current that causes the correction coil to generate a magnetic field that cancels the applied magnetism (geomagnetism entering from the input surface substrate). A current in a predetermined direction and magnitude is supplied from the power supply to the correction coil according to an instruction from the control means. The magnetic field generated from the correction coil by the current cancels the magnetism entering from the input surface substrate.

Even if the direction of the image intensifier is changed, the magnetism entering from the input surface substrate in that direction is automatically canceled out by the action of each part as described above.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a diagram showing a schematic configuration of a magnetostriction correction mechanism provided in an image intensifier device according to an embodiment of the present invention, and FIG.
FIG. 3A is a cross-sectional view taken along line AA of FIG. In addition, in the configuration shown in FIG. 1 and the following FIGS. 2 to 4, the parts denoted by the same reference numerals as those in FIGS. 5 and 6 have the same configuration as the conventional example.
The detailed description here is omitted.

The magnetostriction correction mechanism according to this embodiment includes a correction coil 10, a power supply 11, a magnetic sensor 21, and a control unit 22.

The correction coil 10 wound around the outer peripheral space of the input surface substrate 1 is arranged at an arbitrary position in the input surface substrate region NR formed between the vertical planes sandwiching the input surface substrate 1. This incident surface substrate region NR is a region formed between two vertical planes sandwiching the input surface substrate 1 when a vertical plane is virtually provided with respect to the input surface substrate 1. (A), a vertical plane TP1 in contact with the center NO of the input surface substrate 1;
This is an area between the input surface substrate 1 and the vertical plane TP2 that is in contact with the outer peripheral edge NG. In this embodiment, the correction coil 10
Are arranged inside the vertical plane TP2. The correction coil 10 of this embodiment has a configuration in which the coil is wound a plurality of times, but may be configured with a single-turn coil.

The power supply 11 is for supplying a current to the correction coil 10, and is configured to be controlled by a control unit described later.

The magnetic sensor 21 is for detecting the magnitude and direction of the magnetism, and is composed of, for example, a fluxgate sensor or a sensor using a Hall element, and is configured to detect the magnitude and direction of the detected magnetism. It is configured to output a signal and supply it to a control unit described later. The magnetic sensor 21 is provided in the gap region KR between the input surface substrate 1 and the correction coil 10 arranged as described above, and in the input surface substrate region NR, that is, in the two regions KR,
It is arranged at an arbitrary position in the donut-shaped region WR where the NRs overlap. In this embodiment, the magnetic sensor 21 is
The input surface substrate 1 is arranged near the outer peripheral edge NG.

The control section 22 is provided with a magnetic field (geomagnetism entering from the input surface substrate 1) given from the magnetic sensor 21.
The power supply 11 is controlled so as to supply the correction coil 10 with a current that causes the correction coil 10 to generate a magnetic field that cancels out the geomagnetism entering from the input surface substrate 1 based on an electric signal corresponding to the magnitude and direction of the input surface substrate 1. Is configured.

Next, the operation of the magnetostriction correcting mechanism having the above configuration will be described. The magnetic sensor 21 detects terrestrial magnetism coming from the input surface substrate 1 and supplies an electric signal according to the magnitude and direction of the detected terrestrial magnetism to the control unit 22. The control unit 22 controls the power supply 11 based on the supplied data so that the correction coil 10 generates a magnetic field that cancels out the geomagnetism. The current supplied from the power supply 11 cancels out the terrestrial magnetism entering from the input surface substrate 1 by the magnetic field generated from the correction coil 10. In the I device, the phenomenon that the photoelectrons emitted from the input surface substrate 1 are distorted by geomagnetism and the visible light image is distorted can be eliminated.

An example of a control method by the control unit 22 will be described with reference to FIG. For example, it is assumed that the geomagnetism IB coming from the input surface substrate 1 is in a state as shown in FIG. 2A, and the data given from the magnetic sensor 21 to the control unit 22 at that time is “+ 10v”. At this time, in order to generate a magnetic field HB from the correction coil 11 as shown by a dotted arrow in FIG. 2B, the control unit 22 causes the current i to flow in the direction shown by the arrow in FIG. The power supply 11 is controlled. Also, from the magnetic sensor 21 to the control unit 22
The power supply 11 is controlled so that a current having such a magnitude that the magnetic field HB is generated from the correction coil 10 is supplied to the correction coil 11 so that the data given to the correction coil 11 becomes “0v”.

If the data supplied from the magnetic sensor 21 to the control unit 22 is "-10v", the control unit 22 supplies a current of the same magnitude to the correction coil 10 in the opposite direction. Next, the power supply 11 is controlled.

That is, the controller 22 controls the magnetic sensor 21
The direction of the current is controlled by the sign of the data given by the controller, and the amount of the current is controlled by the magnitude of the absolute value of the data.

By the way, as shown in FIG. 3, the vicinity of the region where the magnetic sensor 21 is arranged is magnetically shielded with a ferromagnetic metal 6, so that the influence of the metal 6
The magnitude of the geomagnetism IB detected by the magnetic sensor 21 may include an error. For example, an electric signal corresponding to the magnitude of the terrestrial magnetism actually entering from the input surface substrate 1 (for example, the magnetic sensor 21 is disposed in front of the center NO of the input surface substrate 1 and the magnitude of the terrestrial magnetism when detected) Although the electric signal is “+ 1v”, the electric signal corresponding to the magnitude of the geomagnetism when the magnetic sensor 21 is arranged at the position shown in FIG. 1 and detected may be “+ 2v”. In such a case, when a magnetic field is generated from the correction coil 10 by the control method described above, the input surface substrate 1
The magnetic field corresponding to “−1v” remains. Therefore, in such a case, the error is measured in advance, and the error is measured as an offset value (in the above case, “−
1v ”), adds the data provided from the magnetic sensor 21 and the offset value, and based on the resulting data (in the above case,“ + 1v ”), supplies the power in the same manner as described above. 11 may be controlled. If the offset value is stored as an absolute value (for example, “+ 1v” in the above case), the magnetic sensor 21
What is necessary is just to subtract the offset value from the data given from.

In this embodiment, the correction coil 10 is arranged inside the vertical plane TP2. However, as described above, if the correction coil 10 is arranged at an arbitrary position in the input surface substrate region NR. Good. By arranging the correction coil 10 at such a position, the terrestrial magnetism can be changed to the I.I. It can be prevented from entering the I device. In order to more effectively block the earth magnetism by the correction coil 10, the correction coil 10 is preferably arranged in the input surface substrate region NR.

In this embodiment, the magnetic sensor 21
Are arranged near the outer peripheral edge NG of the input surface substrate 1, but as described above, the magnetic sensor 21
R and the input surface substrate region NR may be arranged at an arbitrary position in the overlapping region WR. If the magnetic sensor 21 is arranged on the front surface of the input surface substrate 1 (especially, the front surface of the center NO of the input surface substrate 1), geomagnetism coming from the input surface substrate 1 can be detected with the highest accuracy. 21
Is arranged on the front surface of the input surface substrate 1, a shadow of the magnetic sensor 21 is formed on the X-ray image incident on the incident surface substrate 1. Therefore, the magnetic sensor 21 can be arranged on the front surface of the input surface substrate 1. Can not. Therefore, by arranging the magnetic sensor 21 at the position as described above, the direction and magnitude of the terrestrial magnetism entering from the input surface substrate 1 can be detected as accurately as possible. In order to detect the direction and magnitude of the terrestrial magnetism coming from the input surface substrate 1 with higher accuracy, it is preferable that the magnetic sensor 21 be disposed in the region WR.

In the above embodiment, the magnetic sensor 21
Is used to detect the terrestrial magnetism entering from the input surface substrate 1. However, as shown in FIG. 4, a plurality of (two in FIG. 4) magnetic sensors 21 are used to detect the input surface. The geomagnetism entering from the substrate 1 is detected, and the control unit 22 calculates the average of the detection results of the magnetic sensors 21,
The power supply 11 may be controlled based on the average value. With such a configuration, the geomagnetism entering from the input surface substrate 1 can be more accurately grasped by the control unit 22, so that the magnetic field correction by the correction coil 10 can be performed more accurately. However, each magnetic sensor 2
As shown in FIG. 4, it is preferable that the 1s are arranged at positions symmetrical to each other.

[0029]

As is apparent from the above description, according to the present invention, the magnetism (magnitude and direction of the terrestrial magnetism) entering from the input surface substrate is detected by the magnetic sensor, and the control is performed based on the detection result. The means is configured to control the power supply to cancel the geomagnetism with the magnetic field generated from the correction coil, so that regardless of the geographical conditions in which the image intensifier is placed and the change in the direction in which the image intensifier is directed. In addition, since the geomagnetism can always be automatically canceled, a visible light image without distortion can always be obtained from the image intensifier.

Further, since the geomagnetism is automatically canceled, the troublesome operation of adjusting the magnetic field generated from the correction coil can be eliminated.

Further, since the correction coil is arranged in the input surface substrate area, it is possible to prevent geomagnetism from entering from inside the image intensifier device behind the input surface substrate. In the gap area,
In addition, since it is arranged in the input surface substrate region, it is possible to detect the magnetism (the direction and magnitude of the terrestrial magnetism) entering from the input surface substrate as accurately as possible.

[Brief description of the drawings]

FIG. 1A is a diagram showing a schematic configuration of a magnetostriction correcting mechanism provided in an image intensifier according to an embodiment of the present invention. (B): It is sectional drawing in the AA arrow of FIG.1 (a).

FIG. 2 is a diagram for explaining a control method of a control unit.

FIG. 3 is a diagram for explaining a detection error of a magnetic sensor.

FIG. 4 is a diagram showing a schematic configuration of a modified embodiment.

FIG. 5 is a diagram illustrating a configuration of an image intensifier device.

FIG. 6 is a diagram showing a schematic configuration of a magnetostriction correcting mechanism provided in a conventional apparatus, as viewed from an X-ray incident direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Input surface board 10 ... Correction coil 11 ... Power supply 21 ... Magnetic sensor 22 ... Control part NR ... Input surface substrate area KR ... Gap area

Claims (1)

(57) [Claims] 1. An input surface substrate for outputting a photoelectron image according to an incident X-ray image, an electron lens system for reducing and forming the photoelectron image, and an electronic image reduced and formed by the electron lens system for visible light. In an image intensifier in which an output phosphor screen for converting and outputting an image is housed in a tube container, a magnetic sensor, a correction coil wound around an outer peripheral space of the input surface substrate, and a current supplied to the correction coil A power supply, and control means for controlling the power supply so as to supply the correction coil with a current such that the correction coil generates a magnetic field for canceling the magnetism detected by the magnetic sensor;
The correction coil is arranged to sandwich the input surface substrate in the optical axis direction.
The magnetic sensor is disposed in an input surface substrate region formed between the virtual vertical planes, and the magnetic sensor is a region around the axis of the tube container, and further includes the input surface substrate and the correction coil. An image intensifier device, wherein the image intensifier device is disposed in a region where the gap region, which is a region located between the input surface substrate region, and the input surface substrate region.