JP4692111B2 - 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.

  In general, as shown in FIG. 4, a size that fits in a pocket 101 of a radiation worker 100 (also referred to as a user) (for example, 100 × 50 × 10 mm) for detection and management of radiation dose exposed to a radiation worker. 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. 5, 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. 6, 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. 8, 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 a 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, and the buzzer 72 is driven at this frequency. It is necessary to let 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, in the conventional buzzer drive circuit, since the buzzer 72 has a structure in which the diaphragm 85 is attached to the casing 86 via the attachment portion 83, loosening or the like due to secular change occurs in this portion, and FIG. ), The frequency (maximum sound pressure frequency) Hz required to generate the maximum sound pressure (dB) at the buzzer 72 changes year by year. Although the maximum sound pressure frequency changes from year to year in this way, since the signal of the maximum sound pressure frequency at the time of shipment is applied from the CPU 65 to the buzzer 72, as shown in FIG. There is a problem that the maximum sound pressure is reduced.

Further, the buzzer 72 has a variation in the frequency at which the maximum sound pressure can be obtained due to component variations of the piezoelectric element 81 and the metal plate 82 and assembly variations when the diaphragm 85 is attached to the housing 86 via the attachment portion 83. Arise. For this reason, the buzzer 72 must be replaced when a predetermined amount of sound pressure cannot be obtained in the shipping inspection, which increases the man-hours required for parts and replacement, resulting in the cost of manufacturing the dosimeter. There is a problem of becoming higher.
The present invention has been made in view of such problems, the lines can be prevented that the maximum sound pressure of the buzzer is reduced with aging, also Ru can lower the manufacturing cost of the dosimeter The purpose is to provide a meter.

In order to achieve the above object, a dosimeter according to claim 1 of the present invention is a buzzer that generates a sound by applying a frequency signal oscillated from an oscillating means to a buzzer that resonates and outputs sound by a resonance tube. A drive circuit , the buzzer drive circuit detecting a sound of the buzzer provided in a dosimeter charger, a sound pressure level detected by the microphone, and detecting the detected sound pressure Frequency variable means for variably controlling the frequency of the oscillating means up and down so that the level becomes maximum, and calculation for calculating a maximum sound pressure frequency that is a frequency when the sound pressure level detected by the frequency variable means is maximum means and a storage means for storing the maximum sound pressure frequency calculated by said calculation means, and the adjustment mode for calculating and storing the maximum sound pressure frequency, the maximum sound pressure frequency stored in the storage means Control means for performing control to switch to a normal mode for sounding the buzzer with a frequency signal from the oscillating means corresponding to the maximum sound pressure frequency, and selecting the adjustment mode and the normal mode The microphone is electrically connected to the frequency varying means of the buzzer driving circuit when mounted on the charger, and the control means automatically returns to the normal mode after the adjustment mode. Control is performed .
According to this configuration, since it is possible to obtain and store the maximum sound pressure frequency for causing the buzzer to sound at the maximum sound pressure, even if the maximum sound pressure frequency of the buzzer has changed over time, The maximum sound pressure frequency of the buzzer can be obtained. This can prevent the maximum sound pressure of the buzzer from being lowered.

Further, as the adjustment mode buzzer driver circuit when required by the switch, it can be adjusted to pronounce at the maximum sound pressure frequency required at present is performed. This can prevent the maximum sound pressure of the buzzer from being lowered.
Further, when the dosimeter is charged, the buzzer driving circuit can be automatically set in the adjustment mode so that sound generation is performed at the maximum sound pressure frequency required at the present time. This can prevent the maximum sound pressure of the buzzer from being lowered.

Further, the dosimeter by claim 2 of the present invention, Oite to claim 1, wherein, after the time required for storing the maximum sound pressure frequency adjustment mode, the control of returning to the normal mode It is characterized by performing.
According to this configuration, the user does not forget to return to the normal mode after the adjustment mode switching operation.

  As described above, according to the present invention, it is possible to prevent the maximum sound pressure of the buzzer from decreasing due to secular change, and it is possible to reduce the manufacturing cost of the dosimeter.

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 perspective view 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. 5 in that the dosimeter 1 is arranged on the signal processing circuit board 10 in the vicinity of the buzzer 72 and the CPU 65 as shown in FIG. The buzzer driving circuit 5 having the connected microphone 4 is mounted. The microphone 4 detects sound from the buzzer 72.

Further, as shown in FIG. 3, the buzzer driving circuit 5 includes an oscillation unit 11, a frequency variable unit 12, a maximum sound pressure frequency calculation unit 13, a frequency storage unit 14, which are elements realized by the CPU 65, A mode switching control unit 15 and an operation switch 16 outside the CPU 65.
The oscillating unit 11 oscillates a frequency signal that causes the buzzer 72 to sound.
The frequency variable unit 12 detects the sound pressure level detected by the microphone 4 and variably controls the frequency of the oscillating unit 11 up and down so that the detected sound pressure level becomes maximum.
The maximum sound pressure frequency calculation unit 13 calculates a frequency when the sound pressure level detected by the frequency variable unit 12 is maximum, and stores the maximum sound pressure frequency in the frequency storage unit 14.

  The mode switching control unit 15 performs control for switching to an adjustment mode for adjusting the sound pressure level generated by the buzzer 72 so as to be maximum, or a control for switching to the normal mode for normal use of the dosimeter 1 within the broken line frame. This is for the component. Selection of the adjustment mode and the normal mode is performed according to the operation of the operation switch 16. In the adjustment mode, control is performed to enable only the data write operation of the microphone 4, the frequency variable unit 12, the maximum sound pressure frequency calculation unit 13, and the frequency storage unit 14. In the normal mode, control for enabling only the data reading operation of the frequency storage unit 14 is performed.

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, when the user carries the dosimeter 1, the operation switch 16 performs an operation for setting the adjustment mode. Only the data write operation of the microphone 4, the frequency variable unit 12, the maximum sound pressure frequency calculation unit 13, and the frequency storage unit 14 is validated by the switching control of the mode switching control unit 15 according to this operation.

Then, a frequency signal that causes the buzzer 72 to sound is oscillated from the oscillating unit 11, and a sound is generated from the buzzer 72 at a volume corresponding to the frequency signal. When this sound is detected by the microphone 4 and input to the frequency variable unit 12, the sound pressure level is detected by the frequency variable unit 12, and the frequency of the oscillating unit 11 is increased and decreased so that this sound pressure level is maximized. It is variably controlled.
When this variable control is executed, the maximum sound pressure frequency calculation unit 13 calculates a frequency when the sound pressure level detected by the frequency variable unit 12 is maximum. The maximum sound pressure frequency is stored in the frequency storage unit 14. Since the time until this storage is roughly determined, the user performs an operation for setting the normal mode with the operation switch 16 when the time is exceeded.

By the switching control of the mode switching control unit 15 according to this operation, control for enabling only the data reading operation of the frequency storage unit 14 is performed.
Thereafter, for example, when the user exceeds a predetermined exposure amount during work in the radiation work area, the maximum sound pressure frequency stored in the frequency storage unit 14 is read out to the oscillating unit 11 in the dosimeter 1. As a result, the maximum sound pressure frequency signal is oscillated from the oscillating unit 11 to the buzzer 72, so that a warning sound having the maximum sound pressure is generated from the buzzer 72.

As described above, according to the dosimeter 1 using the buzzer driving circuit 5 of the present embodiment, the maximum sound pressure necessary for generating the maximum sound pressure at the buzzer 72 of the buzzer driving circuit 5 according to the secular change. Even if the frequency changes, the user can adjust the buzzer drive circuit 5 to the adjustment mode so that the sound is generated at the maximum sound pressure frequency required at the present time. Thereby, it is possible to prevent the maximum sound pressure of the buzzer from being lowered due to secular change.
In addition, when the adjustment switch is operated with the operation switch 16, the mode switching control unit 15 performs control to automatically return to the normal mode after the time necessary for adjustment to achieve the maximum sound pressure. Good. In this case, the user does not forget to return to the normal mode after the adjustment mode switching operation.

  The adjustment mode can also be applied to a shipment inspection at the time of manufacturing the dosimeter 1. The buzzer 72 may vary in the frequency at which the maximum sound pressure can be obtained due to component variations or assembly variations. For this reason, the buzzer 72 must be replaced if a predetermined amount of sound pressure is not obtained in the shipping inspection. I had to. However, since adjustment can be made so that sound is generated at the maximum sound pressure frequency in the adjustment mode, it is not necessary to exchange the sound. As a result, the replacement of the buzzer 72 increases the work cost for parts, replacement, and the like. As a result, the manufacturing cost of the dosimeter has increased. However, since the replacement is eliminated, the manufacturing cost of the dosimeter is reduced accordingly. Can be lowered.

  In addition, the microphone 4 of the buzzer driving circuit 5 is eliminated, and is instead provided in a charger (not shown) of the dosimeter 1, and when the dosimeter 1 is attached to the charger, the microphone 4 is a frequency variable unit of the buzzer driving circuit 5. The operation switch 16 may be automatically turned on and automatically returned to the normal mode after the adjustment mode by the automatic switching control of the mode switching control unit 15. According to this configuration, when the dosimeter 1 is charged, the buzzer drive circuit 5 can be automatically set in the adjustment mode so that sound generation is performed at the maximum sound pressure frequency required at the present time. In this case, the user never forgets the adjustment.

It is a perspective view which shows the structure of the dosimeter using the buzzer drive circuit which concerns on embodiment of this invention. It is a block diagram which shows the circuit structure of the signal processing circuit board of the dosimeter which concerns on the said embodiment. It is a block diagram which shows the structure of the buzzer drive circuit in the signal processing circuit board of the said dosimeter. 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. (A) Relationship diagram between maximum sound pressure frequency of buzzer and secular change, (b) Relationship diagram between maximum sound pressure and secular variation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,40 Dosimeter 4 Microphone 5,53 Buzzer drive circuit 11 Oscillation part 12 Frequency variable part 13 Maximum sound pressure frequency calculation part 14 Frequency storage part 15 Mode switching control part 16 Operation switch 41 Liquid crystal display 42 Finger insertion prevention network 50 Signal processing Circuit board 61 Reverse bias application unit 62 Semiconductor detection unit 63 Amplifier 64 Comparator 65 CPU
66 Buzzer portion 67 Communication portion 70 Protective sheet 71 Resonant tube 72 Buzzer 81 Piezoelectric element 82 Metal plate 83 Mounting portion 85 Vibration plate 86 Housing

Claims (2)

Equipped with a buzzer drive circuit that produces a sound by applying a frequency signal oscillated from an oscillating means to a buzzer that resonates and outputs sound with a resonance tube ,
The buzzer driving circuit is
A microphone for detecting the sound of the buzzer provided in the charger for the dosimeter ;
A frequency variable means for detecting a sound pressure level detected by the microphone and variably controlling the frequency of the oscillating means up and down so that the detected sound pressure level is maximized;
Calculating means for calculating a maximum sound pressure frequency that is a frequency when the sound pressure level detected by the frequency variable means is maximum;
Storage means for storing the maximum sound pressure frequency calculated by the calculation means;
An adjustment mode for calculating and storing the maximum sound pressure frequency and a maximum sound pressure frequency stored in the storage means are read out, and the buzzer is read by a frequency signal from the oscillation means corresponding to the maximum sound pressure frequency. Control means for performing control to switch to the normal mode for generating sound,
A switch for selecting the adjustment mode and the normal mode;
With
The microphone is electrically connected to the frequency variable means of the buzzer driving circuit when attached to the charger, and the control means performs control to automatically return to the normal mode after the adjustment mode. A dosimeter characterized by that. The dosimeter according to claim 1, wherein the control means performs control to return to the normal mode after elapse of time necessary for storing the maximum sound pressure frequency in the adjustment mode .

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