JPH03215774A - Magnetic field communication type individual exposure dosimeter - Google Patents

Abstract

PURPOSE:To obtain the fast, noncontact, and small type dosimeter equipped with a communication means which is free from a communication error by providing a magnetically shielded radiation sensor and the primary coil of a pulse transformer which generates and outputs a varying magnetic field to the outside of a case. CONSTITUTION:The shield case 11 as the outer package of the dosimeter 1 is formed of, for example, conductive plastic. A radiation sensor 12 which detects radiation may be a GM tube or semiconductor detector. A magnetic shield 13 covering the sensor 12 protects the sensor 12 so that the sensor 12 is not affected by an alternating magnetic field, etc. This shield 13 is made of a material which is metal for shielding the sensor 12 electrostatically and magnetically and has high magnetic permeability, i.e. mumetal. An electronic circuit 14 processes the signal from the sensor 12 to display, store, and process measurement data into data for external communications. Then the primary coil 17 for the external communications is incorporated in a coil- incorporated insulating film 16 provided along the right internal wall of the case 11 and the varying magnetic field for transmitting the measurement data is generated and sent out of the case.

Description

[Detailed description of the invention] [Industrial application field]

This invention relates to a personal exposure dosimeter that measures the radiation dose of each individual in order to manage people engaged in work that is exposed to radiation at nuclear power generation facilities, nuclear fuel reprocessing facilities, accelerator facilities, etc. In particular, it relates to a magnetic field communication type personal exposure dosimeter that has a function of outputting a pulsed magnetic field to the outside and transmitting measurement data, etc. Note that in the following figures, the same reference numerals indicate the same or corresponding parts.

[Conventional technology]

This type of personal exposure dosimeter has the function of emitting an alarm when a predetermined cumulative dose is reached, prompting people to leave the exposed area, displaying the cumulative dose, and transmitting the value externally. There are things that I have. Conventionally, the optical pulse method shown in Fig. 6 and the electrical contact method shown in Fig. 7 have been used as means for externally transmitting and outputting data such as integrated dose values in personal exposure dosimeters having such an external transmission function. Ta. In other words, in both figures, 1 is a personal radiation exposure meter, 2 and 3 in Figure 6 are a light emitting element and a light receiving element for communicating with the outside, and 4 in Figure 7 is an electric meter for communicating with the outside. This is a point of contact. Both of these personal exposure dosimeters shown in Figure 6 or Figure 7 communicate data in accordance with a predetermined communication format using light or electrical conductors, respectively, and are convenient for use in controlling access to and from radiation-controlled areas. First, it is necessary to complete communication with the outside in a short time.

[Problem to be solved by the invention]

In the light pulse method shown in Fig. 6, the light emitting element 2, the light receiving element 3, and their drive circuit (not shown) are essential, and compared to other components, in order to miniaturize the personal exposure dosimeter, The relative dimensions of the above-mentioned optical components are difficult to ignore. Furthermore, in order to eliminate communication errors, it is necessary to align the optical axes of the personal exposure dosimeter and the external data reading/writing device, and mechanical precision is required for the coupling device between the two. Furthermore, if a parallel transmission method is adopted for the purpose of increasing data transmission speed, a plurality of sets of receiving/emitting elements will be required, and the above-mentioned dimensional problem will further increase. On the other hand, although the electrical contact method shown in FIG. 7 has the advantage of being able to perform parallel transmission using multiple contacts, there is always a risk of communication errors due to poor contact between the contacts. Therefore, the present invention solves these problems and provides a high-speed, non-contact 2
It is an object of the present invention to provide a magnetic field communication type personal exposure dosimeter that is small and equipped with a communication means free from communication errors.

[Means to solve the problem]

In order to solve the above-mentioned problems, the personal exposure dosimeter of the present invention is a personal exposure dosimeter that measures the amount of radiation that an individual has been exposed to, which has a small amount of attenuation of a fluctuating magnetic field and radiation, and has an electrostatic shielding function. A radiation sensor (such as 12) housed in this case and further magnetically shielded (via magnetic shield 13 or the like), and a case (such as shield case 11) having A primary coil (such as 17) of a pulse transformer that generates and outputs a fluctuating magnetic field outside the case to transmit measurement data such as radiation dose.
or further, ``the primary coil has a planar shape and is sandwiched between flat insulators (coil-embedded insulating film 16, etc.), and parallel signals for parallel transmission. 1, which is made up of multiple items equal to the number
shall do so.

[For use]

The primary coil on the personal dosimeter side and the 2nd coil on the external reader side
An induced electromotive force (Vi) represented by dl acts between the secondary coils, and communication between the personal exposure dosimeter of the present invention and the reading device is performed by transmitting this Vi in a non-contact manner. Here, mutual inductance M becomes a problem. This M is 1
Next, the medium between the secondary coils and the geometric dimensions of these two coils. If the number of windings cannot be increased with a planar coil as shown in the present invention and the possible magnetic flux density is low, for example, a 10 μl layer between both coils may vary greatly depending on conditions such as arrangement. Inserting an aluminum plate also makes M extremely small. Therefore, in the present invention, conductive plastic or the like is used for the case material of the personal exposure dosimeter to provide an electrostatic shielding effect without significantly reducing the mutual inductance M. In addition, in the present invention, the first order. Since M changes greatly depending on the geometrical conditions of the secondary coil,
Make the distance between both coils close to each other. Then, the spacing between the plurality of planar coils installed in each of the personal exposure dosimeter and the reading device is narrowed, thereby making it possible to arrange the number of coils corresponding to the number of parallel signals of parallel transmission on a small plane.

【Example】

The present invention will be explained below based on FIGS. 1 to 5. FIG. 4 shows an embodiment of a combined arrangement of a personal exposure dosimeter 1 according to the invention and a magnetic reading head 5 as its external communication partner. That is, the dosimeter 1 faces the reading head 5 at a predetermined position and communicates with the reading head 5 in a non-contact manner. (Substantially, the reading head 5 reads data from the dosimeter 1.) FIG. 1 is a sectional view showing an embodiment of the configuration of the personal exposure dosimeter 1 of the present invention. In the same figure, 11 is a shield case which becomes the outer shell of this dosimeter 1, and this shield case 1
For example, conductive plastic 7. Alternatively, use one in which metal is vapor-deposited on the inner surface of the plastic case. In the case of metal vapor deposition, the thickness of the vapor deposition is 3 μm or less, and this vapor deposition layer is reliably connected to the 0 line of the electronic circuit 14, which will be described later. 12 is a radiation sensor that detects radiation, and this sensor 1
2 may be a GM (Giga Muller) tube or a semiconductor detector. A magnetic shield 13 surrounds the radiation sensor 12, and is used to protect the radiation sensor 12 from being affected by alternating magnetic fields and the like. The magnetic shield 13 is a metal that serves both as an electrostatic shield and a magnetic shield for the radiation sensor 12, and is made of a material with high magnetic permeability, such as mu-metal vermalloy or pure iron. It should be noted that from this magnetic shield l3, only a lead wire (not shown) for the radiation sensor l2 enters and exits through a small hole. 14 is an electronic circuit that processes signals from the radiation sensor and displays, stores, and processes measurement data into data for external communication; 15 is an electronic circuit that processes signals from the radiation sensor 14 and the electronic circuit 14;
This is a printed board on which various parts are mounted. In this example, reference numeral 16 denotes an insulating film with a built-in coil provided along the right inner wall of the shield case 11, and as described later, a coil (16) for external communication is disposed inside this insulating film 16.
(also referred to as a secondary coil) 17 is incorporated. Note that 51 is a coil (also referred to as a secondary coil) provided on the head side to communicate with the dosimeter I when the dosimeter 1 faces the magnetic reading head 5. FIG. 2 is an embodiment of a front view of the coil-embedded insulating film 16 in which the primary coil 17 is incorporated. In this example, 16 primary coils I7 (17A~
17P) is incorporated, and of this coil 17A-
17F is a data lotus coil, 17I to 17K are handshake coils, and 17L to 17P are lotus control coils. Here, the number of coils and their roles can be changed depending on the communication method. FIG. 3 is an explanatory diagram of the detailed configuration of the opposing primary and secondary coil portions and the communication method. That is, the personal exposure dosimeter 1 of the present invention
, an insulating film 16 (1
A primary coil 17 is sandwiched between the coils 6A and 16B in a planar manner. When a pulsed current signal is applied to the primary coil 17, the magnetic reading head 5 is placed at a nearby opposing position.
If a secondary coil 51 is installed, 1
The signal current on the secondary coil 17 side can be transmitted to the secondary coil 51 side. That is, in FIG. 3, the insulating film 1
The primary coil inserted between 6A and 16B, for example 17
If a pulsed current signal is passed through A, a signal current can be induced in the secondary coil 514 which is disposed opposite to each other in a non-contact manner. Furthermore, by reversing the roles of both coils 17A and 51A at this time, bidirectional communication becomes possible. Here, the primary coil 17
The primary coil 17B adjacent to A and the secondary coil 51
By installing the secondary coil 51B adjacent to A to a distance where the cage flux of the primary coil 17A and secondary coil 51A is not a problem, parallel transmission can be performed using multiple transmission paths, increasing the speed of data transmission. It becomes possible to aim for. Furthermore, due to the thickness limitations of this dosimeter 1, it is not possible to increase the number of turns of the primary coil 17, and therefore it is difficult to obtain a large magnetic flux density. In order to reduce the magnetic shielding effect as much as possible, the shield case 11 is made of conductive plastic or a case made of aluminum vapor-deposited on plastic, as described above. Figure 5 shows the shield case 11 with a thickness of 1 μm in Figure 3.
Using plastic with thick metal vapor deposition, the distance between the outer circumferences of each of the primary coils 17A and 17B is set to 7-,
When a +5V rectangular wave with a width of 1.0 psec is applied to the primary coil 17A at a repetition frequency of 10 KHz, the voltage induced in the secondary coil 51A and the primary coil 17A,
The relationship between the distances between the secondary coils 514 is shown. It can be seen from FIG. 5 that data can be exchanged without contact if the distance between the primary coil 178 and the secondary coil 51A is within several generations. Note that under the above conditions, the induced voltage to the adjacent primary coil 17B and secondary coil 51B is 0.5 V or less, and if an appropriate threshold is set, the influence on the surrounding coils can be excluded.

【Effect of the invention】

According to the present invention, a personal exposure dosimeter for measuring the amount of radiation that an individual has been exposed to includes a shield case 1l that has a small amount of attenuation of fluctuating magnetic fields and radiation, and has an electrostatic shielding function; , and a radiation sensor 12 magnetically shielded via a magnetic shield 13, which is also housed in the case 11 and generates and outputs a fluctuating magnetic field to transmit measurement data such as the exposure radiation dose to the outside of the case. A primary coil 17 of a pulse transformer is provided, or the primary coil 17 has a planar shape and is sandwiched between coil-embedded insulating films 16 as flat insulators, and for parallel transmission. Because it consists of multiple units equal to the number of parallel signals, the personal dosimeter can be configured compactly, and there is no need to worry about contact failures like in the past. High-speed data communication can be performed with the reading device through parallel transmission.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the configuration of an embodiment of the present invention, FIG. 2 is a front view of the insulating film with a built-in coil, FIG. 3 is an explanatory diagram of the detailed configuration of the coil portion and the communication method, Figure 4 is a combination layout diagram of a personal exposure dosimeter and magnetic reading head, Figure 5 is a diagram showing the relationship between the distance between the primary and secondary coils and the communication induced voltage, and Figures 6 and 7. are external views showing different configuration examples of conventional personal exposure dosimeters. 12 Personal exposure dosimeter, 5: Magnetic reading head, 11: Shield case, 12: Radiation sensor, 13: Magnetic shield, 14: Electronic circuit, 15: Printed board, 16 (16A,
16B): Insulating film with built-in coil, 17 (17A
~17P): Primary coil, 51 (51A, 51B)
: Secondary coil.

Claims (1)

[Scope of Claims] 1) A personal exposure dosimeter for measuring radiation to which an individual is exposed, comprising: a case that has a variable magnetic field and small attenuation of radiation, and has an electrostatic shielding function; , further comprising a magnetically shielded radiation sensor, and a primary coil of a pulse transformer that is also housed in the case and generates and outputs a fluctuating magnetic field outside the case for transmitting measurement data such as the exposure radiation dose. A magnetic field communication type personal exposure dosimeter characterized by: 2) In the personal exposure dosimeter according to claim 1, the primary coil has a planar shape and is sandwiched between flat insulators, and the primary coil has a plurality of parallel signals equal to the number of parallel signals for parallel transmission. A magnetic field communication type personal exposure dosimeter characterized in that it consists of two individual radiation dosimeters.