JP4692094B2 - Dosimeter - Google Patents

Description

The present invention is incorporated in a small dosimeter for personal exposure management used in nuclear power plants, accelerator facilities, radiation utilization facilities, etc., and informs the user of the dosimeter of dangerous exposure status by means of buzzer sound. on the dosimeter buzzer drive circuits are mounted.

  Generally, the size (for example, 100 × 50 × 10 mm) that fits in the pocket 101 of a radiation worker 100 (also referred to as a user), as shown in FIG. A pocket dosimeter (simply referred to as a dosimeter) 40 is used. Generally, the semiconductor type using the ionization action by the incident radiation is the mainstream for the pocket dosimeter, and the semiconductor type will be described in this patent specification.

As shown in FIG. 3, the dosimeter 40 includes a liquid crystal display 41 and a finger insertion prevention network 42 for displaying the current exposure amount of the radiation worker, and a management area when the exposure exceeds the specified value. And a signal processing circuit board 50 on which a buzzer driving circuit 53 for generating an alarm for prompting the user to leave the vehicle is mounted.
As shown in FIG. 4, the signal processing circuit board 50 includes a reverse bias application unit 61, a semiconductor detection unit 62, an amplifier 63, a comparator 64, a CPU 65, a buzzer unit 66, and a communication unit 67. It is configured. However, the CPU 65 that controls the signal processing circuit board 50 and the buzzer unit 66 constitute a buzzer driving circuit 53 as described later.

The semiconductor detection unit 62 has a diode structure in which an n-type semiconductor and a p-type semiconductor are joined by a pn junction. If a negative electrode is connected to the p-type side and a positive electrode to the n-type side by the reverse bias applying unit 61 to such a semiconductor detection unit (diode) 62, electrons are shifted from the n-side to the p-side, and the depletion layer is formed. Further spread.
When radiation is incident on such a depletion layer region, electrons covalently bonded in the depletion layer are repelled, and an electron-hole pair (electron-hole pair) is formed. Electrons move in the + direction and holes move in the-direction toward the reverse-biased electric field. This flow of electrons and holes becomes a current, and this minute current is output from the semiconductor detection unit 62 as a result of radiation exposure.

This minute current is amplified by the amplifier 63 and this amplified signal is compared with a predetermined threshold voltage by the comparator 64. As a result, when the amplified signal becomes equal to or higher than the threshold voltage, a pulse signal is output to the CPU 65. Then, the CPU 65 counts the pulse signal as the radiation dose.
The CPU 65 displays the radiation dose on the liquid crystal display 41, and the radiation worker can check the radiation dose in real time by viewing this. Further, the exposure amount is transmitted from the CPU 65 to the exposure amount centralized management system (not shown) via the communication unit 67. This makes it possible to statistically manage the transition and cumulative value of the radiation dose of radiation workers.

In addition, when a radiation worker exceeds a predetermined exposure amount during work, an alarm sound is emitted from the buzzer unit 66 under the control of the CPU 65 in order to urge the worker to leave the work space.
The configuration of the buzzer 66 is shown in FIG. (A) is an external perspective view of the portion of the buzzer 66 in the dosimeter 40, and (b) is an A1-A2 cross-sectional view shown in (a). The buzzer portion 66 includes a finger insertion prevention net 42, a protective sheet 70, a resonance tube 71, and a buzzer 72.

The finger insertion prevention net 42 is for protecting the protective sheet 70 provided at the opening of the resonance tube 71 without breaking when handling the dosimeter 40. The protective sheet 70 is for preventing dust from adhering to a vibration plate (not shown) of the buzzer 72 via the resonance tube 71.
As shown in the cross-sectional view of FIG. 6, the buzzer 72 includes a vibration plate 85 in which a plate-like piezoelectric element 81 and a metal plate 82 are bonded, and an attachment portion 83 for attaching the vibration plate 85 to the housing 86. The sound wave is generated by the vibration of the diaphragm 85.

The resonance tube 71 resonates the sound wave emitted from the buzzer 72 and generates a sound pressure higher than the sound pressure emitted by the buzzer 72 alone. Here, the resonant tube 71 employs a Helmholtz type resonant tube.
In order to obtain the highest sound pressure from the buzzer portion 66 to the outside, the resonance frequency of the resonance tube 71 may be the same as the frequency at which the maximum sound pressure of the buzzer 72 alone can be obtained. 72 needs to be driven. Here, the resonance frequency between Helmholtz type resonances is determined by the volume V in the resonance tube 71, the thickness L of the opening, and the area S of the opening.

For this reason, in the conventional dosimeter 40, the frequency at which the maximum sound pressure of the buzzer 72 is obtained is previously written in the control program of the CPU 65, and the buzzer 72 is driven and controlled at this frequency.
Examples of this type of conventional buzzer driving circuit and dosimeters equipped with the buzzer driving circuit include those described in Patent Documents 1 and 2, for example.
Japanese Patent Laid-Open No. 2003-248058 JP-A-7-209432

However, since the buzzer 72 of the conventional dosimeter 40 does not operate unless there is a predetermined amount of exposure, the buzzer 72 usually does not sound when handled by the user. For this reason, in the buzzer 72 having a structure in which the diaphragm 85 is attached to the casing 86 via the attachment portion 83 made of an elastic material such as rubber, the attachment portion 83 is cured with aging and the buzzer sound pressure is reduced. There's a problem.
In order to prevent this, conventionally, as shown in FIG. 7, when the dosimeter 40 is inserted into the charger 90 and set, or when the dosimeter 40 is removed from the charger 90, a very short time is required. (1 second or less), the buzzer 72 was sounded to vibrate the attachment portion 83 to alleviate curing. However, since the time for sounding the buzzer 72 is very short, the hardening of the attachment portion 83 cannot be sufficiently mitigated. In addition, it is difficult to sound the buzzer 72 for a long time in order to alleviate the hardening of the attachment portion 83 because the working environment of the radiation worker is deteriorated.

The present invention has been made in view of such a problem, and it is possible to mitigate the hardening of the mounting portion of the buzzer diaphragm accompanying the secular change so as not to deteriorate the working environment of the radiation worker. An object of the present invention is to provide a dosimeter equipped with a buzzer driving device that can prevent a reduction in sound pressure of a buzzer due to secular change.

In order to achieve the above object, a dosimeter according to claim 1 of the present invention applies a frequency signal oscillated from an oscillating means to a buzzer that generates a sound wave by the vibration of a diaphragm attached to a casing by a mounting portion. While playing by the frequency before SL signal applied from the oscillation means to the buzzer, audio frequency and to vibrate the vibrating plate at audio frequencies audible to humans, the vibrating plate at an inaudible frequency inaudible to humans It is equipped with a buzzer drive circuit having a variable control means for controlling to be any one of the inaudible frequencies to be vibrated, and has a detecting means for detecting a charging state set in a charger, and the detecting means is in a charging state When the signal is detected, the variable control means controls the frequency signal from the oscillation means to be the inaudible frequency .
According to this configuration, since the vibration plate of the buzzer can be vibrated at an inaudible frequency, and the attachment portion can also be vibrated by this vibration, the hardening of the attachment portion due to secular change may be a noise that may be noise depending on the surrounding environment. It is possible to mitigate without generating noise, thereby preventing a reduction in buzzer sound pressure due to secular change.

The line meter tall vibrates the vibration plate of the buzzer at an inaudible frequency during charging, it is possible to also mount portion is vibrated by the vibration, the hardening of the mounting portion of the buzzer diaphragm due to aging, radiation work The worker's working environment can be relaxed so as not to deteriorate, thereby preventing the buzzer sound pressure from being reduced due to secular change.

  As described above, according to the present invention, it is possible to mitigate the hardening of the attachment portion of the buzzer diaphragm accompanying the secular change so as not to deteriorate the working environment of the radiation worker, and thereby the buzzer sound due to the secular change. There is an effect that pressure reduction can be prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, parts corresponding to each other in all the drawings in this specification are denoted by the same reference numerals, and description of the overlapping parts will be omitted as appropriate.
FIG. 1 is a block diagram showing a configuration of a dosimeter using a buzzer driving circuit according to an embodiment of the present invention.
The dosimeter 1 shown in FIG. 1 is different from the conventional dosimeter 40 shown in FIG. 3 in that when the dosimeter 1 is set in the charger 90, the diaphragm 85 of the buzzer 72 cannot be heard by humans. This is because it is made to vibrate at a frequency (inaudible frequency).
As a configuration for this purpose, the buzzer driving circuit 5 includes an oscillation unit 11, a frequency variable control unit 12, and a mode switching control unit 13 that are elements realized by the CPU 65, and a charge set detection unit 14 outside the CPU 65. It is prepared for.

The oscillating unit 11 oscillates a frequency signal that causes the buzzer 72 to sound.
The charge set detection unit 14 detects a charge state in which the dosimeter 1 is set in the charger 90.
The mode switching control unit 13 performs control to switch to the charging mode in which the charging state is detected by the charging set detection unit 14 or the normal mode for normal use of the dosimeter 1.
The frequency variable control unit 12 is a signal of an audible frequency (or a maximum sound pressure frequency) for causing the buzzer 72 to vibrate at a frequency of less than 20 Hz that can be heard by humans in the normal mode. And variably controlled so as to be a signal of an inaudible frequency in the charging mode.

The operation of the buzzer driving circuit 5 having such a configuration will be described.
Since the buzzer drive circuit 5 is in the normal mode as an initial state, for example, when a user carrying the dosimeter 1 exceeds a predetermined exposure amount during work in the radiation work area, the variable frequency control unit 12 The audible frequency signal is oscillated from the oscillating unit 11 to the buzzer 72 by the control of the above, so that an audible sound pressure warning sound is generated from the buzzer 72.

  On the other hand, when the user leaves the radiation work area and sets the dosimeter 1 in the charger 90, the charging state of the dosimeter 1 is detected by the charging set detection unit 14, and the mode switching control unit 13 enters the charging mode. Can be switched. In this charging mode, an inaudible frequency signal is oscillated from the oscillating unit 11 to the buzzer 72 under the control of the frequency variable control unit 12, so that the diaphragm 85 of the buzzer 72 vibrates at the inaudible frequency. In this case, the attachment portion 83 connected to the diaphragm 85 also vibrates.

  As described above, according to the dosimeter 1 using the buzzer driving circuit 5 of this embodiment, the diaphragm 85 of the buzzer 72 is vibrated at an inaudible frequency during charging, and the attachment portion 83 is also vibrated by this vibration. be able to. Accordingly, the hardening of the mounting portion of the buzzer diaphragm accompanying the secular change can be mitigated so as not to deteriorate the working environment of the radiation worker, thereby preventing the reduction of the buzzer sound pressure due to the secular change. .

It is a block diagram which shows the structure of the dosimeter using the buzzer drive circuit which concerns on embodiment of this invention. It is a figure which shows the mounting state of the pocket dosimeter to the radiation worker. It is a perspective view which shows the structure of the dosimeter using the conventional buzzer drive circuit. It is a block diagram which shows the circuit structure of the signal processing circuit board of the conventional dosimeter. The structure of a buzzer part is shown, (a) is an external appearance perspective view of the part of the buzzer part in a dosimeter, (b) is A1-A2 sectional drawing shown to (a). It is a section lineblock diagram of a buzzer. It is a perspective view which shows the state which set the dosimeter to the charger.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,40 Dosimeter 5,53 Buzzer drive circuit 11 Oscillation part 12 Frequency variable control part 13 Mode switching control part 14 Charge set detection part 41 Liquid crystal display 42 Finger insertion prevention network 50 Signal processing circuit board 61 Reverse bias application part 62 Semiconductor detection Unit 63 Amplifier 64 Comparator 65 CPU
66 Buzzer portion 67 Communication portion 70 Protective sheet 71 Resonance tube 72 Buzzer 81 Piezoelectric element 82 Metal plate 83 Mounting portion 85 Vibration plate 86 Case 90 Charger

Claims (1)

A buzzer for generating sound waves by the vibration of the vibrating plate mounted by the mounting portion to the housing, is sound by applying a frequency signal oscillated from the oscillation means, from the previous SL oscillating means of the signal applied to the buzzer Variable control means for controlling the frequency to be one of an audible frequency that vibrates the diaphragm at an audible frequency that can be heard by a human and an inaudible frequency that vibrates the diaphragm at an inaudible frequency that cannot be heard by a human. Equipped with a buzzer drive circuit with
A detecting means for detecting a charging state set in the charger;
A dosimeter characterized in that, when the detection means detects a state of charge, the variable control means controls the frequency signal from the oscillation means to be the inaudible frequency .

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