JPH11169438A - Electron beam irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact electron beam irradiation device capable of performing sterilization by electron beams suited to the kind of an object to be sterilized. SOLUTION: By controlling the amount of electrons emitted from an electron gun 3 and made incident on an acceleration tube 6 corresponding to the kind of the object 1 to be sterilized by a current amount control means 18, the electron beams suited to the object 1 to be sterilized is irradiated, and since the need of using a tank like an electrostatic type electron beam irradiation device is eliminated, this device is compacted. Also, by providing a speed control means 17 on a conveyor 2, by slowing or accelerating the carrying speed of the conveyor 2 in the case that the size and weight of the object 1 to be sterilized exceeds a range controllable by the current amount control means 18, the energy value and irradiation amount of the electron beams irradiated to the object 1 to be sterilized become the appropriate size, and thus, the sterilization is performed by more suitable electron beams and the degradation of the conveyor 2 or the like is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film made of Ti or the like which separates a vacuum side and an atmosphere side from an emission port of an acceleration tube which accelerates and emits electrons emitted from an electron gun to high energy with high frequency power. The present invention relates to an electron beam irradiation apparatus for irradiating an object to be sterilized conveyed by a conveyor in the atmosphere with an electron beam passing through the film to sterilize the electron beam.

[0002]

2. Description of the Related Art As a method of sterilizing an object to be sterilized such as medical supplies (syringe, gauze, etc.) and foods, there is a method using ethylene oxide gas. Therefore, an electron beam irradiation apparatus that sterilizes by irradiating an electron beam with no problem of residual gas and simple validation compared with a method using an ethylene oxide gas has attracted attention.

In this electron beam irradiation apparatus, electrons emitted from an electron gun are incident on an acceleration tube, accelerated to high energy by high frequency power from a high frequency power supply, and conveyed to the atmosphere through a film made of Ti or the like by a conveyor. (RF acceleration type) and an electron emitted from an electron gun are accelerated by a grid to which a positive charge is applied in an accelerating section, and the film is conveyed to the atmosphere through a film by a conveyor. There is a type (electrostatic acceleration type) that irradiates a conveyed object to be sterilized by irradiation.

Since the electron beam passages of these electron beam irradiation devices are kept in a vacuum, the electron beam irradiation port is separated from the vacuum side and the atmosphere side by a film (thickness of several tens μm) made of Ti or the like. Have been. That is, the high-energy electron beam accelerated by the acceleration tube penetrates the thin film of Ti and is irradiated to the sterile object in the atmosphere.

[0005]

However, since the energy of the electron beam is fixed in the above-mentioned conventional RF type electron beam irradiating apparatus, whether the size of the object 1a to be sterilized is large as shown in FIG. Or, if heavy, the electron beam L indicated by a broken line
1 may stop halfway and sterilization may be insufficient.
When the object 1b to be sterilized is a thin object or a minute object, when a high-energy electron beam is applied, the electron beam L2 penetrates the object to be sterilized and is applied to the conveyor 2 or the like. This is accelerated (the electron beams L3 and L4 show ideal irradiation).

FIG. 4 is a schematic diagram showing the state of irradiation of an object to be sterilized with an electron beam irradiated from a conventional electron beam irradiation apparatus.

Further, the electrostatic type electron beam irradiation apparatus has a large size of the accelerating portion main body, and furthermore, since the accelerating portion, the electron gun and the like are arranged in the tank and the tank is filled with SF6, the size becomes large. There was a problem.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a compact electron beam irradiation apparatus which can be sterilized with an electron beam suitable for the type of an object to be sterilized.

[0009]

In order to achieve the above-mentioned object, the present invention provides an electron beam emitted from an electron gun, which is accelerated to high energy with high frequency power and emitted.
A film made of Ti or the like that separates the vacuum side from the atmosphere side is provided. Current amount control means for controlling the amount of electrons emitted from the electron gun is provided in the electron gun.

According to the present invention, in addition to the above configuration, the current amount control means determines the energy value and the irradiation amount of the electron beam according to the type of the object to be sterilized, and generates a signal representing the energy value and the irradiation amount. It is preferable to include a generator and a heater power supply for applying a voltage based on a signal from the signal generator to the heater of the electron gun for a predetermined time.

[0011] In addition to the above configuration, the present invention provides a speed for controlling the conveying speed of the conveyor so that the irradiation amount and the energy value of the electron beam irradiated to the object to be sterilized are optimized when the control range of the current amount control means is exceeded. Preferably, the control means is provided on the conveyor.

Here, an accelerating tube for accelerating an electron beam with high-frequency power has a property that, when a constant high-frequency power is applied, the amount of electrons (current amount) and the energy are substantially inversely proportional. Therefore, by controlling the amount of electrons incident on the accelerating tube, the magnitude of the acceleration energy can be controlled. For example, if the amount of current incident on the accelerator is several tens mA, the energy of the electron beam can be accelerated to several MV. If the amount of current incident on the accelerator is several A, the energy of the electron beam can be accelerated to several hundred kV. Can be done. Therefore, by controlling the amount of electrons emitted from the electron gun, the amount of electron beams emitted from the accelerator tube can be controlled.

According to the present invention, by controlling the amount of electrons emitted from the electron gun according to the type of the object to be sterilized, an electron beam suitable for the object to be sterilized is irradiated, and the electrostatic type electron beam is irradiated. Since there is no need to use a tank as in the case of a line irradiation device, the size is reduced.

Further, by providing the speed control means on the conveyor, when the size and weight of the object to be sterilized exceed predetermined conditions, the conveying speed of the conveyor is reduced so that the size and weight of the object to be sterilized are constant. If the conditions are not satisfied, increasing the conveyor speed will make the energy value and irradiation amount of the electron beam irradiated to the object to be sterilized appropriate, so sterilize with a more suitable electron beam. Can be.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of an electron beam irradiation apparatus according to the present invention.

Reference numeral 3 denotes an electron gun body 4 for accelerating electrons emitted from a cathode heated by a heater by a grid (both not shown), and electrons for deflecting by a focusing coil 5 to emit electrons in a predetermined direction. It is a gun.

An accelerating tube 6 for accelerating electrons by high-frequency power is connected to an emission port of the electron gun 3 via a metal tube (for example, a copper tube) 7.

The accelerating tube 6 has a substantially cylindrical housing (for example, a diameter of about 50 mm) 6a and a plurality (not limited to eight in the figure) of cells arranged in the housing 6a at predetermined intervals. And a high-frequency input unit 6 formed on the side of the housing 6a on the side of the electron beam entrance to which high-frequency power is input.
c, and a focusing coil 6d arranged on the outer periphery of the housing 6a to prevent a bundle of electron beams sequentially accelerated in each cell from expanding due to a space charge effect. Housing 6 of accelerating tube 6
a and the disk 6b are made of, for example, copper.

The high-frequency input section 6c of the acceleration tube 6 has a waveguide 8
The high frequency power supply 9 is connected via the. The high-frequency power source generates high-frequency power having a frequency of 2 GHz (S band or X-band of 9 GHz may be used) and an output of several MW in a pulse shape (pulse width several μsec, cycle several tens to several hundreds / sec). ing.

On the emission side (lower side in the figure) of the acceleration tube 6, a pyramid horn antenna-shaped irradiation nozzle 11 as an emission port is mounted via a metal tube 10. A coil 12 for scanning an electron beam is provided on the outer periphery of the metal tube 10.

At the opening of the irradiation nozzle 11, a metal plate (for example, a copper plate) 14 having a plurality of (but not limited to five in the figure) windows 13 as shown in FIG. 2 is attached. Each window 13 has a Ti film (several tens μm thick).
m) 15 is attached. FIG. 2 is a bottom view of the irradiation nozzle of the electron beam irradiation apparatus shown in FIG.

Here, the electron gun 3 and the acceleration tube 6 shown in FIG.
Since the system for accelerating electrons at a high frequency is kept in a vacuum, it cannot irradiate the object 1 placed in the atmosphere as it is. Thus, a Ti film 15 that separates the vacuum side (electron gun 3, accelerating tube 6, high-frequency power supply 9 and the like) from the atmosphere side (the object 1 to be sterilized, a conveyor 2 described later, etc.) and transmits an electron beam is used. . Note that the metal plate 14 is preferably cooled (for example, water-cooled) because it generates heat when irradiated with an electron beam.

A conveyor 2 driven by a motor 16 is arranged below the irradiation nozzle 11, and the object 1 to be sterilized is conveyed by the conveyor 2. Conveyor 2
The speed control means 17 controls the transport speed of the conveyor 2 so that the irradiation amount and the energy value of the electron beam applied to the object 1 are optimized when the type of the object 1 deviates from a certain condition. Is provided.

The object 1 to be sterilized is conveyed by such a conveyor 2 and is sterilized by being irradiated with an electron beam when passing directly below the irradiation nozzle 11.

On the other hand, the heater of the electron gun 1 has a current amount controlling means 18 for controlling the temperature of the cathode in accordance with the type of the object to be sterilized, thereby controlling the magnitude of the current of the electrons emitted from the electron gun 1. Is provided.

The current amount control means 18 determines a radiation amount of an electron beam suitable for sterilizing an object to be sterilized, and generates a signal representing the energy value of the electron beam;
A heater power supply 20 is configured to apply a voltage to the heater of the electron gun 3 so that the temperature of the cathode of the electron gun 3 becomes a temperature corresponding to the energy value when receiving a signal from the signal generator 19.

The signal generator 19 determines the weight and outer shape of the object 1 using a weight sensor and a number of photo sensors not shown.

Here, the characteristics of the acceleration tube 6 will be described.

FIG. 3 is a diagram showing the relationship between the current (acceleration current) accelerated by the acceleration tube 6 used in the electron beam irradiation apparatus shown in FIG. 1 and the acceleration energy. In the figure, the horizontal axis is the acceleration current, and the vertical axis is the acceleration energy.

As shown in FIG. 3, when a constant high-frequency power is applied to an accelerating tube 6 for accelerating electrons with high-frequency power,
It can be seen that the amount of the accelerated electrons (the amount of current) and the energy show characteristics that are substantially inversely proportional.

The electron beam irradiation apparatus shown in FIG. 1 can control the acceleration energy of the electrons by controlling the amount of electrons incident on the accelerator tube 6 from the electron gun 3. That is, by using the electron gun 3 that changes the magnitude of the emission current from several mA to several A and the accelerator tube 6 that can accelerate electrons of several tens mA to energy of several MV, several MV /
An electron beam of several tens mA to several hundred kV / several A is applied to the Ti film 15.
To the object 1 to be sterilized.

The size of the object 1 to be sterilized conveyed by the conveyor 2 ranges from large to small and varies in weight from heavy to light. By controlling the amount of electrons emitted from the electron gun 6 in accordance with the type of the sterile object 1, the object 1 to be sterilized is irradiated with an electron beam.

That is, the signal generator 19 of the current amount control means 18 outputs a signal indicating that the heater voltage of the electron gun 3 is increased when the weight of the object 1 is light, small or thin. Then, a high voltage is applied to the heater of the electron gun 3 from the heater power supply 20. For this reason, electrons of a large current are incident on the acceleration tube 6 from the cathode. When a large current of electrons is incident on the accelerating tube 6, an electron beam having a low acceleration energy is irradiated on the object 1 through the Ti film 15.

On the contrary, the signal generator 19 of the current amount control means 18 has a function to lower the heater voltage of the electron gun 3 when the weight of the object 1 is heavy, large or thick. A low voltage is applied from the heater power supply 20 to the heater of the electron gun 3. Therefore, electrons of a small current are incident on the acceleration tube 6 from the cathode. When a small current of electrons is incident on the accelerating tube 6, an electron beam of high accelerating energy passes through the Ti film 15 and the object 1
Is irradiated.

Here, the speed control means 17 controls the speed of the object 1 to be sterilized.
If the weight or the magnitude of the current exceeds the range that can be controlled only by the current amount control means 18, the rotation speed of the motor 16 is controlled to control the transport speed of the conveyor 2.
That is, when the weight of the object 1 is extremely light, extremely small, or extremely thin, the conveying speed of the conveyor 2 is increased, and when the weight of the object 1 is extremely heavy, Conveyor 2 if large or extremely thick
The transport speed is reduced. This allows
Irrespective of the type of the object 1 to be sterilized, it is possible to irradiate an optimal electron beam, perform sufficient sterilization, and minimize deterioration of the conveyor 2 and the like.

In the present embodiment, the case where one Ti film is used has been described. However, the present invention is not limited to this. If the pressure in both Ti films is detected by making the Ti films double, It is possible to detect the breakage of one of the Ti films while separating the vacuum side and the atmosphere side, thereby protecting the electron gun, the acceleration tube and the like.

[0038]

In summary, according to the present invention, the following excellent effects are exhibited.

By controlling the amount of electrons emitted from the electron gun according to the type of the object to be sterilized, it is possible to sterilize with an electron beam suitable for the object to be sterilized and to provide a compact electron beam irradiation apparatus. Can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an electron beam irradiation apparatus according to the present invention.

FIG. 2 is a bottom view of an irradiation nozzle of the electron beam irradiation apparatus shown in FIG.

FIG. 3 is a diagram showing a relationship between current (acceleration current) accelerated by an acceleration tube used in the electron beam irradiation apparatus shown in FIG. 1 and acceleration energy.

FIG. 4 is a schematic diagram showing an irradiation state of an electron beam irradiated from a conventional electron beam irradiation apparatus on an object to be sterilized.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sterilized object 2 Conveyor 3 Electron gun 6 Acceleration tube 17 Speed control means 18 Current amount control means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01J 33/00 H01J 33/00

Claims (3)

[Claims] 1. An acceleration tube for accelerating electrons emitted from an electron gun to high energy with high frequency power and emitting the same,
An electron beam irradiation apparatus for providing a film made of Ti or the like separating a vacuum side and an atmosphere side, and irradiating an electron beam passing through the film to an object to be sterilized conveyed by a conveyor in the atmosphere to sterilize the film. An electron beam irradiation apparatus, wherein the electron gun is provided with current amount control means for controlling the amount of electrons emitted from the electron gun according to the type of object. 2. A signal generator for determining an energy value and an irradiation amount of an electron beam according to a type of an object to be sterilized, and generating a signal representing the energy value and the irradiation amount. 2. The electron beam irradiation apparatus according to claim 1, comprising a heater power supply for applying a voltage based on a signal from a signal generator to a heater of the electron gun for a predetermined time. 3. A speed control means for controlling a conveyor speed so as to optimize an irradiation amount and an energy value of an electron beam irradiated on an object to be sterilized when the control range of the current amount control means is exceeded. The electron beam irradiation apparatus according to claim 2, wherein the electron beam irradiation apparatus is provided.