JPS6242359Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a grain moisture content measuring device, and more particularly to a measuring circuit that reduces measurement errors caused by self-heating of semiconductor circuit elements.

In the conventional moisture content measuring device, the moisture content value is obtained by crushing and clamping the sample grain between electrodes. In the measurement circuit, the measurement switch that commands the start of each measurement turns on the power to the entire measurement circuit.
It is common to keep it turned off and display the measurement results only when measurement is being performed.

By the way, when trying to add a function to this type of moisture content measuring device that sequentially stores the moisture content values obtained for each measurement and calculates the average value, the measuring circuit can be turned on and off by turning the measuring switch on and off. If energization is performed, the measurement circuit will not be energized except during measurement, and the moisture content values sequentially stored in the measurement circuit will be erased, making it impossible to calculate the average value. Therefore, it is conceivable to use a nonvolatile memory element that does not erase the memory when the power is turned off, but this is not preferable in terms of space and cost. For this reason, the power to the measurement circuit is continued during measurement regardless of whether the measurement switch is ON or OFF, to prevent the memory from being erased.
A measurement circuit that only displays the moisture content value when turned OFF is conceivable, but in this case, the following points need to be taken into consideration. In other words, the time required for a measurer to repeat multiple measurements and find the average value of moisture content is considerably longer than when calculating a single moisture content value, and also varies depending on the measurer. . This means that the time for energizing the measuring circuit increases when determining the average value.
In particular, in the analog circuit section of the measurement circuit, which is adjusted within a predetermined time in consideration of characteristic changes caused by self-heating of semiconductor circuit elements due to energization, an increase in energization time causes measurement errors during measurement. becomes. Furthermore, an increase in the energization time when calculating the average value accelerates the consumption of battery power that serves as a power source.

The present invention was developed in consideration of the above circumstances, and when calculating the average value of moisture content, the current to the analog circuit is controlled by a measurement switch.
The purpose is to solve the above-mentioned problems caused by self-heating of semiconductor circuit elements by turning them ON and OFF.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an external plan view of a manual moisture measuring device to which the present invention is applied. 1 is a housing;
A transparent display window 2 is formed on its upper surface, and numerical display elements 3 and 4 are provided below the display window 2 to display the moisture content value and the number of measurements, respectively. Further, the numeric display element 3 is provided with a decimal point indicator light 5 which also serves as a power indicator light. Further, in the vicinity of the display window 2, there are provided an average value switch 6 for instructing the numerical display element 3 to display an average value based on the measured moisture content values, and a power switch 7 for opening and closing the power supply.
Next, inside the housing 1 (not shown), a circuit board comprising a measurement circuit is fixed on a flat surface, and
Stores power batteries, measurement aids, etc. In addition, a handle 8 for crushing grains is provided on the right end side of the housing 1, and by manually rotating the handle 8, the sample grains interposed between a pair of electrodes consisting of an upper electrode and a lower electrode located at the bottom of the handle 8 are crushed. Crush and clamp. A stopper 9 is provided to regulate the rotation angle of the handle 8 and keep the electrode interval constant during crushing. A measurement switch 10 is provided at a position where the rotation of the handle 8 is restricted by a stopper 9, and is turned on and off according to the rotation of the handle 8 by a magnet provided on the handle 8.
It will be turned off.

Next, FIG. 2 is a block diagram of a measuring circuit showing an embodiment of the present invention. A battery 11 serves as a power source for the circuit, and when the power switch 7 is closed, voltage is supplied between the power lines 12 and 13.
A capacitor 14 for noise prevention is connected between the power lines 12 and 13, and a voltage conversion circuit 15 is connected via the measurement switch 10, and power lines 16 and 17 are connected to the output voltage side thereof. A pair of electrodes 1 is connected between the power supply lines 16 and 17.
Resistance/voltage conversion circuit 19 which inputs the electrical resistance value of the sample grain crushed and clamped between 8 and converts it into a voltage signal.
Connect. Also, between power lines 12 and 17,
A grain temperature detection circuit 20 that outputs a voltage signal corresponding to the temperature of the sample grain at the time of crushing, and an A/D conversion circuit 21 that inputs the voltage signal and converts it into a digital signal.
are connected to convert the output voltages of the resistance/voltage conversion circuit 19 and the grain temperature detection circuit 20, which constitute the analog circuit section, into digital signals, respectively. Next, a digital signal from the A/D conversion circuit 21 is input between the power supply lines 12 and 13, and the water content value, average value,
Arithmetic circuit unit 2 that performs arithmetic processing according to a program prepared in advance to display the number of measurements, etc.
2, and a display driver circuit 23 for driving the numeric display elements 3 and 4. 24 is a switch circuit for outputting the operating state of the measurement switch 10 to the arithmetic circuit section 22, and together with the average value switch 6 that commands the display of the average value, the arithmetic circuit section 2
Connected to the input terminal of 2.

Next, the operation of this embodiment will be explained. First, the measurer closes the power switch 7 and connects the power line 12,
The voltage of the battery 11 is supplied between 13 and 13. The arithmetic circuit unit 22 starts the program by supplying this voltage. Next, when the handle 8 is rotated to crush and sandwich the sample grain between the pair of electrodes 18, the measurement switch 10 is turned on at the same time, and the voltage between the power lines 12 and 13 is supplied to the voltage conversion circuit 15. The voltage converted by the voltage conversion circuit 15 is supplied between the power lines 16 and 17 and at the same time drives the switch circuit 24 to output the ON state of the measurement switch 10 to the arithmetic circuit unit 22. Power line 1
When a voltage is supplied between the electrodes 6 and 17, the analog circuit section consisting of the resistance/voltage conversion circuit 19 and the grain temperature detection circuit 20 generates a voltage signal corresponding to the electrical resistance value of the sample grain crushed and clamped between the electrodes, respectively. , and a voltage signal corresponding to the temperature of the sample grain at the time of crushing, to the A/D conversion circuit 21. The A/D conversion circuit 21 is
After converting each input voltage signal into a digital signal, it is output to the arithmetic circuit section 22 at a predetermined timing. The arithmetic circuit unit 22 is connected to the measurement switch 10
When it is detected through the switch circuit 24 that the switch is turned on, the digital signal from the A/D conversion circuit 21 is input and converted into data on the moisture content value and the number of measurements, and this is output to the display driver circuit 23. and digitally displayed on the numerical display elements 3 and 4. The arithmetic circuit section 22 continues this state until the measuring person turns the handle 8 in the opposite direction and turns off the measuring switch 10. From then on, the moisture content values that are sequentially measured and displayed as the measuring switch 10 is turned on and off are as follows: Arithmetic circuit section 22
is memorized. Next, when the average value switch 6 is turned on, the arithmetic circuit unit 22 calculates the average value based on the plurality of stored moisture content values, and displays this on the numerical display elements 3 and 4 together with the number of measurements. The moisture content value stored in the arithmetic circuit unit 22 continues to be stored unless the power switch 7 is turned off and the power supply between the power lines 12 and 13 is cut off.

In this way, in order to obtain the average moisture content value of a sample grain, it is necessary to repeat the measurement at least multiple times, which takes more time than a single measurement, and the Continuous energization of the measuring circuit is required to store and hold the moisture content values sequentially. However, in this invention,
As mentioned above, the self-heating of semiconductor circuit elements due to energization greatly affects measurement errors during measurement.
The required minimum time can be set by turning ON and OFF. In this embodiment, the measurement switch 10 is
Although ON and OFF are linked to the handle 8, the present invention is not limited to this, and a push button switch that can be opened and closed manually may also be used.

As is clear from the above description, the following effects can be obtained by the measuring circuit of the moisture content measuring device of the present invention.

(1) When calculating the average moisture content value, turn on the power to the analog circuit using the measurement switch.
Since it is turned OFF, measurement errors caused by self-heating of the semiconductor circuit element can be reduced.

(2) Reduces battery power consumption and saves power.

[Brief explanation of the drawing]

FIG. 1 is an external plan view of a moisture content measuring device to which an embodiment of the present invention is applied, and FIG. 2 is an electric circuit block diagram showing a measuring circuit which is an embodiment of the present invention. 6...Average value switch, 7...Power switch,
8...Handle, 10...Measuring switch, 11...
...Battery, 19...Resistance/voltage conversion circuit, 20...
Grain temperature detection circuit, 21... A/D conversion circuit, 22...
...Arithmetic circuit section.

Claims (1)

[Scope of utility model registration request] In a moisture content measuring device that measures the moisture content of a grain by crushing and clamping a sample grain between electrodes, the electric resistance value of the sample grain during crushing is detected and a measurement value signal corresponding to the moisture content of the grain is generated. an analog circuit section for outputting, an arithmetic circuit section for inputting and storing the measurement signal and calculating and outputting the moisture content value and its average value, and a display circuit for inputting and displaying the moisture content value and the average value from the arithmetic circuit. and a measurement switch that is turned off except during measurement to cut off power only to the analog circuit section, on a power line from a battery that supplies power to each of the circuits. measurement circuit.