JPS62119489A - Radiation dosimeter - Google Patents

Abstract

PURPOSE:To generate a warning when the operation of a signal amplifying and waveform shaping unit can not follow the change in density of radiation by providing a signal duration detecting unit between the output side of a comparator and a data processing and displaying circuit. CONSTITUTION:The output signals from a radiation detector 1a that are generated by a radiation are amplified by an amplifier 2a and, after noise components are removed by a band-pass filter 2b, the radiation is detected by a comparator 2c. Then, the radiation is counted by a counting circuit 3a and, on the basis of it, data-processed by a data processing and displaying circuit 3b to be displayed. When radiation dose exceeds a given set count number, a warning is generated. On the other hand, a signal duration detector 5 monitors the output signals of the comparator 2c and, when the output signals of the comparator 2c continue for over a given set time in the condition that the radiation is present, a warning is generated.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention relates to a radiation dosimeter.

[Prior art and its problems]

As a radiation dosimeter, one having the configuration shown in the block diagram of FIG. 4 is known. 1 is a radiation detection section having a radiation detector 1a; 2 is a signal amplification waveform shaping section comprising an amplifier 2a, a bandpass filter 2b and a comparator 2C; 3 is a data processing display section comprising a counting circuit 3a and a data processing display circuit 3b; 4 is a power supply section. To explain this operation, the output signal from the radiation detector 1a generated due to the presence of radiation is amplified by the amplifier 2a, the noise component is removed by the bandpass filter 2b, and the radiation is detected by the comparator 2C.

Next, the radiation dose is counted in the counting circuit 3a, and the data processing and display circuit 3b processes data based on the counted radiation dose to perform various displays.At the same time, when the radiation dose exceeds a certain set count number, It is set to issue a warning.

The problem with this method is that the number of radiation (1
The number of radiation generated per second) and the number counted by the counting circuit 3a are a certain number of radiation N.

Up to N, there is a nearly one-to-one correspondence, but when the number increases beyond N, the number of counts tends to decrease, contrary to the actual increase in the number of radiations. This is a phenomenon that occurs because the operation of the signal amplification waveform shaping section 2 described above cannot follow the density of the number of radiations. For example, the output waveform of the bandpass filter 2b in FIG. 4 has the shape shown by A in FIG.
As the number of radiation increases, it becomes more expensive.

The signal fluctuates slightly beyond the comparison level Vth1 of the next-stage comparator 2C. Therefore, the output waveform of the comparator 2C has the shape shown in B in FIG. 3, and the number of counts decreases, contrary to the increase in the number of radiations.

As described above, conventional radiation dosimeters have a problem in that when the number of radiation increases above a certain level, the number of counts decreases, contrary to the actual increase in the number of radiation.

[Purpose of the invention]

In view of the above-mentioned circumstances, the present invention has been devised to issue an alarm to alert the user of the radiation dosimeter when the operation of the signal amplification waveform shaping section is no longer able to follow the ffi degree of the number of radiation. purpose.

[Key points of the invention]

In order to achieve the above object, this invention provides a signal duration detection section between the output side of the comparator and the data processing display circuit, integrates the output signal of the comparator, and issues an alarm when the integral level exceeds a certain set level. I made it emit.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention, in which the same parts as in the conventional structure are given the same reference numerals.

What is different about the configuration of this embodiment from the conventional one?

By providing the signal duration detection section 5 between the output side of the comparator 2C and the data processing display section 3, the operation is as follows. That is, the output signal from the radiation detector 1a generated by radiation is amplified by the amplifier 2a, the noise component is removed by the bandpass filter 2b, the radiation is detected by the comparator 2C, and this radiation is counted by the counting circuit 3a. The data processing display circuit 3b processes the data based on this.

At the same time as making various displays, an alarm is issued when the radiation dose exceeds a certain set count number. On the other hand, comparator 2C
The signal duration detection section 5 monitors the output signal of the comparator 2C, and issues an alarm if the output signal of the comparator 2C continues for a set time period or longer in which radiation is present (for example, at a low level). This will be explained based on FIG. Figure g2 is a specific electrical circuit diagram of the signal duration detection section 5 described above, where L is an input terminal and M is an output terminal. Comparator 2 is connected to the input terminal.
The output signal of C (waveform shown in FIG. 3B) is input. This B
In the waveform, a low level indicates a state in which radiation is present, and a constant current 1 flows into the capacitor C1 during the low level period. Next, when the output signal of the comparator 2C becomes high level, the transistor T1 is turned on, and the capacitor C1 mentioned above is turned on.
The charge that has flowed into is discharged. Therefore, the terminal voltage V of capacitor C1. The waveform of 1 is as shown in FIG. 3C.

One terminal of the capacitor C1 is connected to one input side of the comparator CP2, and the capacitor C1 terminal voltage is V. 1 exceeds the set voltage vth2, the output of the comparator CP2 becomes low level, and the current I2. I3. I4 is played. This turns on transistor T2, and the terminal voltage vc2 of capacitor C2 is charged as shown in FIG. 3E. Further, a waveform shown in FIG. 8g3 is outputted to the output terminal M.

In this state, even if the comparator CP2 reaches level 71, currents 12, I3, and I4 still flow. Next, when the terminal voltage vC2 of the capacitor C2 exceeds a certain level Vtha, the transistor T3 is turned on. When the transistor T3 is turned on, the transistor T2 is turned off, and the transistor T5 is turned off. At this time, if the comparator CP2 is at a high level, the transistor T4 is turned on, the charge in the capacitor C2 is discharged, and the transistor T3 is turned off, so that the current I2. I3. L will no longer flow.

As a result of the above-described operation, the output level of the comparator 2C becomes low, and when a certain fixed time Tl is reached, the output terminal M of the signal duration detection section 5 outputs the output waveform F at a level of 1.
is output and an alarm is issued. Once the alarm is issued, even if the cause of the alarm disappears, the alarm will continue to sound for a certain set period of time T2 to alert the user.

〔Effect of the invention〕

In this invention, by providing a signal duration detection section between the output side of the comparator and the data processing display circuit, the operation of the signal amplification waveform shaping section can no longer keep up with the increase in the density of the number of radiation. can be detected as the length of the constant mode duration of the output level of the comparator 2C, and can notify the user that the radiation level is dangerous.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the invention. FIG. 2 is an electric circuit diagram of the signal connection time detection section in FIG. 1, FIG. 3 is a waveform diagram of each part in the electric circuit of the present invention, FIG. The figure is a diagram showing the relationship between the number of radiation and the number of counts. 1: radiation level, 1 ae radiation detector, 2: signal amplification waveform shaping section, 2a: amplifier, 2b: bandpass filter,
2C: Comparator, 3: Data processing embedding section, 3a: Counting circuit, 3b = Data processing display circuit, 4: Heart source section, 5: Signal duration detection section.

Claims (1)

[Claims] 1) Signal amplification waveform shaping comprising a radiation detection unit having a radiation detector that generates a signal by radiation, an amplifier that amplifies the signal, a bandpass filter that shapes the waveform of the amplified signal, and a comparator. In the radiation dosimeter, the radiation dosimeter includes a data processing display section including a counting circuit, a data processing display circuit, and a power supply section, and a signal duration detection section is provided between the output side of the comparator and the data processing display circuit. A radiation dosimeter characterized in that the signal state after waveform shaping is configured to issue an alarm when a predetermined period of time elapses in a state in which radiation is present. 2) The radiation dosimeter according to claim 1, characterized in that once the alarm is issued, the alarm continues for a set time regardless of the presence or absence of radiation.