JPH11223700A - Electron beam scanner and scanning method with electron beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly apply an electron beam to a material irradiated with scanning. SOLUTION: An electron beam scanner to scan an electron beam to a material to be irradiated with the scanning of the electron beam includes an electromagnet 1 to deflect the incident electron beam, power supplies 30a, 30b to supply a current to the electromagnet, and a power control means 32 to gradually change the current supplied from the power supplies to the electromagnet and gradually deflecting the incident electron beam to a preset direction and to its opposite direction on an alternate basis for scanning. An electron beam scanning method, in which the elecronmagent 11 to deflect the incident electron beam is used to scan the electron beam deflected by the electromagnet for irradiating the material to be irradiated, comprises gradually changing the current supplied to the electromagnet and gradually deflecting the incident electron beam to a preset direction and to its opposite direction on an alternate basis for scanning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam scanning apparatus for irradiating an object with an electron beam by scanning and a scanning method using the electron beam, and more particularly to a technique for reducing irradiation unevenness of the electron beam by scanning.

[0002]

2. Description of the Related Art Conventionally, for example, an electron irradiation device used as a sterilizer has been known. This sterilizer converts the kinetic energy of electrons into heat energy by colliding electrons with an object to be irradiated, thereby performing sterilization. FIG. 7 shows a configuration of a main part of such a conventional electron irradiation apparatus. This electron irradiation device includes an electron beam generator 10, an electromagnet 11, which is a part of an electron beam scanning device, an irradiation window 12, and a transport conveyor 13. Conveyor 13
Transports the irradiation object 14 to be irradiated with the electron beam at a predetermined speed. The irradiation window 12 is provided to guide an electron beam from the electron beam generator 10 to an irradiation object 14 conveyed on a conveyor 13.

[0003] As the electron beam generator 10, for example, an electron gun is used. The electron beam generator 10 generates an electron beam A intermittently. In the following, the state where the electron beam A is generated is represented by, for example, a pulse as shown in FIG. The electron beam A generated by the electron beam generator 10 passes through the electromagnet 11 as an electron beam and irradiates the surface of the irradiation object 14. In addition, the electron beam generator 10 generates a timing signal indicating the timing at which the electron beam A is output. This timing signal is supplied to a power supply control unit 22 (details will be described later) of the electron beam scanning device.

The electromagnet 11 constitutes a part of the electron beam scanning device, and is constituted by a scanning coil (neither is shown) wound on a core. The electromagnet 11 is used to accelerate, converge, and deflect the electron beam A output from the electron beam generator 10 based on a current supplied to a scanning coil from a power supply unit 20 described later.

[0005] By controlling the acceleration and convergence of the electron beam A in this manner, the power density of the electron beam A required on the irradiation object 14 is adjusted. The scanning of the electron beam A on the irradiation object 14 is realized by controlling the deflection. In this case, the scanning width is determined by controlling the variable range of the deflection angle, and the scanning speed is determined by controlling the changing speed of the deflection angle.

Next, an electron beam scanning device applied to the conventional electron irradiation device configured as described above will be described with reference to a block diagram shown in FIG. This electron beam scanning device includes an electromagnet 11, a power supply unit 20, a current value setting circuit 21, and a power supply control unit 22.

The power supply section 20 generates a current to be supplied to the electromagnet 11. The magnitude of the current generated by the power supply unit 20, more specifically, the amplitude of a sine wave current described later is determined based on the current value control signal IA output from the current value setting circuit 21. The waveform and output timing of the current generated by the power supply unit 20 are determined by the current waveform control signal IW output from the power supply control unit 22. The current generated by the power supply unit 20 is supplied to the scanning coil of the electromagnet 11 as a scanning coil current IS.

The current value setting circuit 21 receives the above-described current value control signal IA based on a control signal from the power supply control unit 22.
Is generated and supplied to the power supply unit 20. Power control unit 2
2 generates the above-described current waveform control signal IW based on the timing signal from the electron beam generator 10 and supplies it to the power supply unit 20.

The operation of the electron beam scanning apparatus having the above configuration will be described with reference to a timing chart shown in FIG.

FIG. 9A shows a waveform of a scanning coil current IS supplied to the scanning coil of the electromagnet 11. As shown, the scanning coil current IS
Is a discontinuous sinusoidal current. The discontinuous sine wave current is used because the portion of the sine wave current from the predetermined positive value L1 to the predetermined negative value L2 (the portion shown by the solid line in the figure) is the output timing of the electron beam A. This is for synchronization.

FIG. 9B shows the timing at which the electron beam A is output from the electron beam generator 10. The high level (hereinafter, referred to as “H level”) section of each pulse is a section in which the electron beam A is output, and is synchronized with the portion of the sine wave current indicated by the solid line. In this electron beam scanning device,
When the scanning coil current IS is the positive predetermined value L1, the electron beam A from the electron beam generator 10 is deflected to the maximum by the electromagnet 11 and irradiates one end of the irradiation object 14.

From this state, the scanning coil current IS
Decreases, the deflection angle of the electron beam A decreases, and when the scanning coil current IS becomes zero, the deflection angle also becomes zero. In this state, the electron beam A is applied to the center point of the scanning width. From this state, as the scanning coil current IS further decreases (increases in the negative direction), the deflection angle of the electron beam A increases in the opposite direction to the above, and when the scanning coil current IS becomes a predetermined negative value L2. , Electron beam generator 10
Is deflected to the maximum in the opposite direction by the electromagnet 11 to irradiate the other end of the irradiation object. In synchronization with this, the output of the electron beam A stops. The above operation completes one scan in the predetermined direction P.

When this scanning is completed, a scanning coil current IS having a positive predetermined value L1 is supplied to the scanning coil of the electromagnet 11 again at the timing when the next electron beam A is output. The electron beam A is irradiated. The next operation is completed by performing the same operation as described above. In the same manner, the same direction P
The object 14 to be conveyed by being scanned
The entire surface of the substrate is irradiated with the electron beam.

[0014]

The intensity of the electron beam A generated from the electron beam generator 10 fluctuates due to various factors and is not always constant. For example, as shown in FIG. 10, the H level portion of the pulse fluctuates finely, and the flatness is not good. When the object to be irradiated is irradiated by the scanning of the electron beam A, the irradiation amount varies depending on the irradiation position on one scanning line. As a result, there is a place on the object to be irradiated where insufficient irradiation occurs. In addition, since the scanning direction is always one direction, in the next scan, there is a place where irradiation is insufficient at substantially the same irradiation position.

That is, when the irradiation object moving at a constant transport speed is two-dimensionally scanned using the electron beam A having such a poor flatness, the pulse shape of the electron beam A remains unchanged. Since it is reflected in the above-mentioned irradiation amount distribution, as shown in FIG. 11, the irradiation amount variation of the electron beam A on the irradiation object appears as irradiation unevenness as it is. However, a very strict value is required for the uniformity of the amount of electron beam irradiated on the object to be irradiated, and a desired performance cannot be obtained with a conventional electron beam scanning apparatus.

An object of the present invention is to provide an electron beam scanning apparatus and a scanning method using an electron beam, which can uniformly irradiate an irradiation object with an electron beam by scanning.

[0017]

In order to achieve the above object, an electron beam scanning apparatus according to the present invention is an electron beam scanning apparatus for irradiating an object to be irradiated with the electron beam by scanning the electron beam. An electromagnet for deflecting the incident electron beam, a power supply for supplying a current to the electromagnet, and a current supplied from the power supply to the electromagnet is gradually changed, so that the incident electron beam is directed in a predetermined direction. And power supply control means for scanning by alternately and gradually deflecting in the opposite direction.

The upper source in the electron beam scanning device alternately outputs a current having a predetermined polarity and a current having a polarity opposite to the polarity in response to a control signal from the power supply control means. It can be configured to supply to an electromagnet.

Further, the power supply in the electron beam scanning device has a first power supply for gradually increasing the current and a second power supply for gradually decreasing the current, and responds to a control signal from the power supply control device. The current output from the first power source and the current output from the second power source are alternately output and supplied to the electromagnet.

According to the electron beam scanning apparatus according to the present invention, the scanning is performed while the scanning direction is alternately changed. Are averaged, and the object to be irradiated can be uniformly irradiated with the electron beam without excessive or excessive irradiation.

For the same purpose as described above, a scanning method using an electron beam according to the present invention has an electromagnet for deflecting an incident electron beam, and scans the electron beam deflected by the electromagnet. An electron beam scanning method for irradiating an irradiation object by gradually changing the current supplied to the electromagnet,
Thus, the scanning is performed by alternately and gradually deflecting the incident electron beam in a predetermined direction and a direction opposite thereto.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electron beam scanning apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. This electron beam scanning device is used by being incorporated in the electron irradiation device already described with reference to FIG. Therefore, description of the electron irradiation device is omitted.

First, the configuration of the electron beam scanning device according to the embodiment of the present invention will be described with reference to the block diagram shown in FIG. This electron beam scanning device includes an electromagnet 11, a power supply unit 30a, a power supply unit 30b, a current value setting circuit 31, a power supply control unit 32, and a transformer 33.

The power supply section 30a outputs a positive discontinuous sinusoidal current W1 as shown in FIG. The reason why the discontinuous sinusoidal current W1 is used is as follows.
The electron beam A outputs a portion of the sine wave current from a positive predetermined value L1 to a negative predetermined value L2 (a portion shown by a solid line in the drawing, and this portion is particularly referred to as a “first waveform current”). This is to synchronize with the timing.

The amplitude of the sine wave current W1 output from the power supply section 30a is controlled by a current value control signal IA1 from a current value setting circuit 31. Also, the power supply unit 30
The output timing and the shape of the first waveform current output from the current waveform control signal IW
1 is determined. The output from the power supply unit 30a is supplied to a first input terminal of the transformer 33.

The power supply section 30b outputs a negative polarity discontinuous sine wave current W2 as shown in FIG. 2B.
The reason why the discontinuous sine wave current is used is that, similarly to the above, the portion of the sine wave current from the negative predetermined value L3 to the positive predetermined value L4 (the portion indicated by the solid line in the drawing, This part is hereinafter referred to as a “second waveform current” in particular) in order to synchronize the timing at which the electron beam A is output.

The amplitude of the sine wave current W2 output from the power supply 30b is controlled by the current value control signal IA2 from the current value setting circuit 31. Also, the power supply unit 30
The output timing and the shape of the second waveform current output from the current waveform control signal IW
2 is determined. The output from the power supply unit 30b is supplied to a second input terminal of the transformer 33.

The current value setting circuit 31 responds to a control signal from the power supply control unit 32 to determine a current value control signal I for determining the amplitude of the sine wave current W1 output from the power supply unit 30a.
A1 and a current value control signal IA2 for determining the amplitude of the sine wave current W2 output from the power supply unit 30b are generated. The current value control signals IA1 and IA2 generated by the current value setting circuit 31 correspond to the power supply units 30a and 30a, respectively.
b.

The power control unit 32 generates current waveform control signals IW1 and IW2 based on the timing signal from the electron beam generator 10 described above, and supplies them to the power supplies 30a and 30b, respectively. These current waveform control signals IW1 and IW2 are, as described above, sinusoidal currents W1 and W2
Are used to output the first and second waveform current portions in synchronization with the output timing of the electron beam A.

The transformer 33 has two input terminals such as a first input terminal and a second input terminal on the primary side, and one output terminal on the secondary side. The turn ratio between the primary side and the secondary side is, for example, “1: 1”. This transformer 33
Outputs the output of the power supply unit 30a supplied to the first input terminal and the output of the power supply unit 30b supplied to the second input terminal to the output terminal as it is. Thereby, the sine wave current W as shown in FIG.
A current is output in which the first and second waveform current portions 1 and 2 alternately and periodically appear. The current output from the transformer 33 is supplied to a scanning coil (not shown) of the electromagnet 11 as a scanning coil current IS.

As shown in FIG. 5, this electron beam scanning device is different from the electron beam scanning device shown in FIG.
Is removed, and the output from the power supply unit 30a is switched to the changeover switch 34.
And a negative polarity to the first input terminal of the transformer 33 and a negative polarity to the second input terminal. In this case, the switching timing of the switch 34 can be configured to be determined by the switching signal SS generated by the power control unit 32 based on the timing signal from the electron beam generator 10. According to this configuration, a current in which the first and second waveform current portions of the sine wave currents W1 and W2 alternately and periodically appear as in FIG. 2C from the output terminal of the transformer 33. Can be In this case, there is an advantage that the electron beam scanning device can be configured inexpensively and easily because only one power supply unit is required.

The transformer 33 is not used for increasing or decreasing the pressure, but is used for synthesizing the output from the power supply unit 30a and the output from the power supply unit 30b and outputting the combined output. Accordingly, a switch 34 as shown in FIG. 6 can be used in place of the transformer 33. In this case, the switching timing of the switch 34 can be configured to be determined by the switching signal SS generated by the power control unit 32 based on the timing signal from the electron beam generator 10.

Next, the operation of the electron beam scanning apparatus having the above configuration will be described with reference to the timing chart shown in FIG.

As described above, FIG.
2B is a sine wave current W2 output from the power supply unit 30b, and FIG. 2C is a diagram in which the sine wave current W1 and the sine wave current W2 are synthesized by the transformer 33. The waveform of the scanning coil current IS supplied to the scanning coil of the electromagnet 11 is shown. FIG. 2D shows the timing at which the electron beam A is output from the electron beam generator 10. The H level section of each pulse is a section where the electron beam A is output, and is synchronized with the first and second waveform current portions of the sine wave currents W1 and W2.

First, when the output of the electron beam A from the electron beam generator 10 is started, that is, when the pulse P1 in FIG. 2D rises, the electron beam scanning device synchronizes with the pulse P1 in FIG.
A scanning coil current IS having a positive predetermined value L1 shown in (C) is output. Thereby, the electron beam generator 1
The electron beam A from 0 is maximally deflected in one direction by the electromagnet 11 and irradiates one end L of the irradiation object 14.

From this state, the scanning coil current IS
Decreases, the deflection angle of the electron beam A decreases, and when the scanning coil current IS becomes zero, the deflection angle also becomes zero. In this state, the electron beam A is applied to the center point of the scanning width. From this state, as the scanning coil current IS further decreases (increases in the negative direction), the deflection angle of the electron beam A increases in the opposite direction to the above, and when the scanning coil current IS becomes a predetermined negative value L2. , Electron beam generator 10
The electron beam A is deflected by the electromagnet 11 to the maximum in a direction opposite to the above-described position direction, and irradiates the other end R of the irradiation object 14. In synchronization with this, the output of the electron beam A stops. That is, the pulse P1 in FIG. 2D falls. The above operation completes one scan in the direction P.

When this scanning is completed and the output of the next electron beam A from the electron beam generator 10 is started, that is, FIG.
When the pulse P2 of (D) rises, the electron beam scanning device outputs a scanning coil current IS having a negative predetermined value L3 shown in FIG. Thereby, the electron beam A from the electron beam generator 10 is maximally deflected by the electromagnet 11 in the direction opposite to the one direction, and irradiates the other end R of the irradiation object 14.

From this state, the scanning coil current IS
Increases, the deflection angle of the electron beam A decreases, and when the scanning coil current IS becomes zero, the deflection angle also becomes zero. In this state, the electron beam A is applied to the center point of the scanning width. From this state, as the scanning coil current further increases, the deflection angle of the electron beam A increases in the opposite direction to the above, and when the scanning coil current IS becomes a predetermined positive value L4, the electron beam A The electron beam A is maximally deflected in one direction by the electromagnet 11 and irradiates one end L of the irradiation object 14. In synchronization with this, the output of the electron beam A stops. That is, the pulse P2 in FIG.
Falls. With the above operation, one scan in the direction Q opposite to the direction P is completed.

In the same manner, scanning is performed while changing the direction P and the direction Q alternately. FIG. 3 shows the dose distribution of the electron beam A on the irradiation target when scanning in the direction P and the dose distribution of the electron beam A on the scanning line when scanning in the direction Q. Note that L in the pulse in FIG. 3 corresponds to one end of the irradiation target 14, and R corresponds to the other end. In this manner, the scanning is performed while the direction P and the direction Q are alternately changed, so that the electron beam A is irradiated on the surface of the object 14 to be conveyed. FIG. 4 shows the dose distribution on the surface of the irradiation object in this case.

According to the electron beam scanning device that operates as described above, the pulse shape generated from the electron beam generator 10 is always constant. It is possible to make up for the shortage.
This makes it possible to uniformly irradiate the irradiation target with the electron beam, thereby reducing the above-described non-uniform irradiation due to the variation in the pulse flatness.

In the example described above, the center point of the scanning width is fixed, but it may be desirable to change the center point of the scanning width depending on the size and shape of the irradiation target. In such a case, a DC bias may be applied to the entire scanning coil current IS output from the transformer 33. According to this configuration, it is possible to freely set the center point of the scanning width by changing the bias current.

In the above-described example, the electron beam scanning apparatus for handling an electron beam has been described. However, the present invention is not limited to the electron beam, but may be any irradiation apparatus that irradiates light, laser, ions, or the like by scanning. It can be widely used regardless of the magnitude of the energy of the medium to be handled.

[0043]

As described in detail above, according to the present invention,
An electron beam scanning device and a scanning method using an electron beam, which can uniformly irradiate an irradiation object with an electron beam by scanning, can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an electron beam scanning device according to an embodiment of the present invention.

FIG. 2 is a timing chart for explaining an operation of the electron beam scanning device according to the embodiment of the present invention.

FIG. 3 is a diagram for explaining a change in the scanning direction and intensity of an electron beam in the electron beam scanning device according to the embodiment of the present invention.

FIG. 4 is a timing chart for explaining the operation of the electron beam scanning device according to the embodiment of the present invention.

FIG. 5 is a block diagram showing another configuration example of the electron beam scanning device according to the embodiment of the present invention.

FIG. 6 is a block diagram showing still another configuration example of the electron beam scanning device according to the embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a main part of an electron irradiation device in which a conventional electron beam scanning device is incorporated.

FIG. 8 is a block diagram showing a configuration of a conventional electron beam scanning device.

FIG. 9 is a timing chart for explaining the operation of a conventional electron beam scanning device.

FIG. 10 is a diagram for explaining a change in a scanning direction and intensity of an electron beam in a conventional electron beam scanning device.

FIG. 11 is a diagram for explaining an irradiation state of an electron beam by a conventional electron beam scanning device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Electron beam generator 11 Electromagnet 12 Irradiation window 13 Conveyor 14 Irradiated object 30a, 30b Power supply unit 31 Current value setting circuit 32 Power supply control unit 33 Transformer 34 Changeover switch

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuichiro Kanna 10 Nagoya City, Nagoya City, Aichi Prefecture 10 Oecho Mitsubishi Heavy Industries, Ltd.

Claims (2)

[Claims] An electron beam scanning device for irradiating an object to be irradiated with an electron beam by scanning the electron beam, comprising: an electromagnet for deflecting an incident electron beam; and supplying a current to the electromagnet. A power supply, and a power supply control means for gradually changing a current supplied from the power supply to the electromagnet and thereby scanning the electron beam by alternately deflecting the incident electron beam alternately in a predetermined direction and the opposite direction. Equipped with an electron beam scanning device. 2. An electron beam scanning method comprising: an electromagnet for deflecting an incident electron beam; and irradiating an object to be irradiated by scanning the electron beam deflected by the electromagnet. A scanning method using an electron beam in which a supplied current is gradually changed, and the incident electron beam is scanned by being alternately and gradually deflected in a predetermined direction and a direction opposite thereto.