JPH06324154A - How to determine when to replace a proportional counter - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for determining when to replace a proportional counter, which aims to improve the economic disadvantage of uniform replacement. A radiation source for irradiating an object to be measured with a primary radiation, a proportional counter for detecting fluorescent X-rays generated in the object to be measured, an amplifier circuit for amplifying an output from the proportional counter, and this amplifier A pulse height discrimination circuit for inputting pulse output from the circuit to perform pulse height discrimination, a counter for inputting output from the pulse height discrimination circuit to count the pulses, and an output from this counter for inputting the output from the counter to the target according to a predetermined algorithm. An exchange processing device is constituted by an arithmetic processing unit for calculating the physical quantity contained in the measurement object, monitors the window voltage of the pulse output from the waveform discriminating circuit, and when the window voltage exceeds a predetermined value.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is to determine the timing of replacement of a proportional counter used for measuring the coating amount of paint applied to paper or the like and the constituent substance (calcium) contained in the sheet-like substance. In this case, the present invention relates to a method for determining when to replace the proportional counter for long-term use.

[0002]

2. Description of the Related Art A paper characteristic measuring device used for measuring end points in a papermaking process is equipped with various sensors such as a grammometer, a moisture meter, and a calcium sensor, so as to be multifunctional. 2 and 3 are a basic configuration diagram of an apparatus and a configuration diagram of a calcium sensor (coating amount meter) for explaining the present invention and a conventional example. As shown in FIG. 2, these sensors are housed in upper and lower heads A and B, which are opposed to each other with a minute gap G in between, and various characteristics of the paper 1 traveling between the gaps G are measured.

FIG. 3 is a block diagram of a calcium sensor for measuring the content of calcium carbonate in the paint applied to the paper 1 among these sensors, and this sensor is arranged in the lower head B. The primary radiation emitted from the ring-shaped radiation source 2 using iron 55 hits the paper 1 and fluorescent X-rays (secondary radiation) are generated by the calcium in the paper. This fluorescent X-ray passes through the central opening of the ring-shaped radiation source 2 and is detected by the proportional counter 3. After the pulse from the proportional counter 3 is amplified by the amplifier 4, the pulse is discriminated by the pulse height discriminating circuit 5, and the output of the pulse height discriminating circuit is guided to the counter to count the number of pulses. Based on the count number, the arithmetic processing unit 7 calculates and displays the measured component amount according to a predetermined algorithm. Calculation is performed and output.

The pulse signal of the fluorescent X-ray detected by the proportional counter 3 in the above apparatus is, for example, as shown in FIG.
As shown in (b) and (c), there are strong ones and weak ones. That is, the one shown in FIG. 3A is the peak voltage a of the pulse.
₃ is the voltage with the upper limit a ₁ and the voltage range with the lower limit a ₂ (delta
Window voltage (hereinafter referred to as ΔWV)), and the one shown in FIG. 6 (b) shows that the peak voltage a _{4 of the} pulse is ΔWV a _{1 at the} upper limit.
And the peak voltage a _{5 of the} pulse is lower than the lower limit voltage ΔWVa ₂ in FIG.
The reason why pulses with different peak values appear in this way is that fluorescent X-rays from components other than the component to be measured (here calcium) emerge, and ΔWV is the signal corresponding to the fluorescent X-rays from calcium. Indicates the range.

Here, it is assumed that the peak voltage shown in (a) of these peak voltages is the pulse signal of the fluorescent X-ray due to calcium, which is higher than the other peak values, and the wave height discrimination circuit 5 uses this ( a) Only pulses having peak values at the upper limit a ₁ and the lower limit a ₂ of ΔWV shown in the figure are allowed to pass. The passing pulse is counted by a counter, and some of the counted value is proportional to the amount of calcium carbonate contained in the paper (coating thickness). The upper limit a ₁ and the lower limit a ₂ of this ΔWV can be arbitrarily changed according to the measurement component.
Moreover, the peak value of the pulse (window voltage) gradually decreases due to deterioration of the proportional counter, but the upper and lower limits of ΔWV also decrease while maintaining that range, and the voltage is automatically adjusted to the voltage that maximizes the count number. To be done.

[0006]

By the way, the sensitivity of the proportional counter used in such a measuring apparatus is deteriorated due to aged deterioration depending on the frequency of use. In addition, the life of the proportional counter varies greatly. Therefore, conventionally, a method of uniformly exchanging after a certain fixed period (for example, 3 years) has been taken.

However, in practice, there are some that can be used for longer than the conditions of use and the year and month specified for each individual, and there is a problem that it is economically disadvantageous to uniformly replace them. The present invention has been made to solve the above problems, and an object of the present invention is to improve economic disadvantages by uniformly replacing proportional counters by individually determining the replacement timing. is there.

[0008]

The structure of the present invention for solving the above problems is a radiation source for irradiating an object to be measured with primary radiation, and a proportional counting for detecting fluorescent X-rays generated in the object to be measured. Tube, an amplifier circuit that amplifies the output from this proportional counter, a pulse height discrimination circuit that inputs the pulse output from this amplification circuit and performs pulse height discrimination, and the output from this pulse height discrimination circuit that inputs the pulse. A counter to count,
It comprises an arithmetic processing unit that inputs the output from this counter and calculates the physical quantity contained in the measured object according to a predetermined algorithm, monitors the window voltage of the pulse output from the waveform discrimination circuit, and It is characterized in that the time of replacement is the time when it exceeds the specified value.

[0009]

The function of the proportional counter decreases with time. The crest discriminator circuit passes only pulses having a predetermined peak value. When the sensitivity decreases, the window voltage decreases, but the time when the pulse peak value exceeds a certain level is determined to be the time for replacing the proportional counter.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. In addition,
Since the configuration of the device is the same as that of the conventional example shown in FIGS. 2 and 3, the description thereof is omitted here. 1 (a) and 1 (b) are explanatory views showing the criteria for the replacement timing of the proportional counter of the present invention.

In the figure, (a) shows the pulse voltage before deterioration over time, and the peak value a ₃ is located near the upper limit a _{1 of} ΔWV. The diagram (b) shows a state in which the window voltage a ₆ is lowered due to deterioration and is lower than, for example, an arbitrarily determined alarm line a ₇ . In the present invention, this drop in window voltage is monitored, and the point in time when this value exceeds a certain level is determined to be the time for replacing the proportional counter.

[0012]

According to the present invention as described in detail with reference to the above embodiments, the window voltage of the pulse output from the waveform discriminating circuit is monitored and when the window voltage exceeds a predetermined value. Since it is determined that it is time to replace, the economical disadvantage can be improved as compared with the conventional method in which the proportional counters are uniformly replaced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an output example for determining a replacement time of the present invention.

FIG. 2 is a basic configuration diagram of an apparatus for explaining the present invention and a conventional example.

FIG. 3 is a configuration diagram of a calcium sensor for explaining the present invention and a conventional example.

FIG. 4 is an explanatory diagram showing an output example of a proportional counter.

[Explanation of symbols]

 A upper head B lower head 1 paper 2 ring-shaped radiation source 3 proportional counter 4 amplification circuit 5 wave height discrimination circuit 6 counter 7 arithmetic processing unit

Claims (1)

[Claims] 1. A radiation source for irradiating an object to be measured with primary radiation, a proportional counter for detecting fluorescent X-rays generated in the object to be measured, and an amplifier circuit for amplifying an output from the proportional counter. A pulse height discrimination circuit for inputting pulse output from this amplifier circuit to perform pulse height discrimination, a counter for inputting output from this pulse height discrimination circuit to count the pulses, and an output from this counter for inputting a predetermined algorithm according to a predetermined algorithm. It comprises an arithmetic processing unit for calculating the physical quantity contained in the measured object, monitors the window voltage of the pulse output from the waveform discriminating circuit, and when the window voltage exceeds a predetermined value, it is regarded as a replacement time. A method for determining when to replace a proportional counter, which is characterized in that