JPH08136336A - Correcting method of temperature characteristic of electronic type balance - Google Patents

Abstract

PURPOSE: To provide a correcting method of the temperature characteristic of an electronic type balance which makes possible execution of accurate weighing without being affected by a change in temperature. CONSTITUTION: An analog circuit part A' is provided with a temperature sensor 50 detecting the temperature of this circuit part, and a computer 41 measures temperature coefficients of a zero point and a span beforehand for each of gains of dead division erasing-regulating circuit 43 and a gain regulating circuit 45 and corrects the zero point and the span on the basis of information on an actual temperature detected by the temperature sensor 50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature characteristic correction method for electronic scales.

[0002]

2. Description of the Related Art FIG. 3 and FIG. 4 show the circuit construction of a conventional electronic scale described above. In FIG. 3, reference numeral 1 is a load cell of the detecting means of the scale, the excitation terminal 2 of which is connected to a power supply terminal 3 of an analog circuit section A described later to supply power, and the output terminal 4 of which is an analog circuit section A. Connected to the input terminal 5, the load detection signal a of the load cell 1 is input to the analog circuit section A, and the exciting terminal 2 is connected to the analog circuit section A.
, And the voltage signal b of the load cell 1 is input to the analog circuit section A.

The analog circuit section A is connected to the input terminal 5, amplifies the load detection signal a of the load cell 1, and outputs a amplified load detection signal a '. A preamplifier 11 is connected to the reference terminal 6 and the load cell 1 is connected. Of the reference amplifier 12 that amplifies the voltage signal b of
Connected to the preamplifier 11 and the waste elimination control circuit 13 and a waste elimination adjustment circuit 13 (described later) which adjusts the reference voltage signal c and outputs a waste elimination signal d corresponding to the waste of the balance. , A subtracter 14 for subtracting the unnecessary elimination signal d from the load detection signal a ′ and outputting a weighing signal e, and a subtractor
14 is connected to the gain adjusting circuit 15 (described later) that adjusts the weighing signal e and outputs the weighing signal e ′, and is connected to the gain adjusting circuit 15 and the reference amplifier 12 and outputs the weighing signal according to the reference voltage signal c. It is composed of an analog-digital converter (hereinafter abbreviated as A / D converter) 16 which converts e ′ into a digital signal f.

The metric digital signal f output from the A / D converter 16 is output to the computer 21 via the output terminal 17, and the computer 21 displays the metric value on a digital display (not shown).

FIG. 4 shows a circuit diagram of the waste elimination adjusting circuit 13. The waste elimination adjusting circuit 13 is a circuit generally called an inverting amplifier circuit using an operational amplifier, and has an input side resistance R _s.
And the resistance value of the resistance R _{f on} the feedback side, the amplification factor (gain)
Can be determined. The feedback-side resistor R _f is configured by connecting a plurality of fixed resistors 31 for coarse adjustment in series, and fixing each of these fixed resistors 31.
And a dip-switch 32 are connected in parallel with each other, and a variable resistor 33 for fine adjustment is further connected in series to the fixed resistor 31.

The circuit of the gain adjusting circuit 15 has the same structure, and its explanation is omitted. However, the variable resistor 33 for fine adjustment is unnecessary. The operation of the above configuration will be described.

The load detection signal a detected by the load cell 1 is amplified by the preamplifier 11, and the subtracter 14 subtracts the waste elimination signal d adjusted by the waste elimination adjusting circuit 13 from the weight detection signal a '. The weighing signal e is obtained, and this output is adjusted by the gain adjusting circuit 15, and the A / D
The digital signal f is converted by the converter 16 and input to the computer 21, and the measured value is displayed on the digital display.

Next, a method of adjusting the gains of the gain adjusting circuit 15 and the waste elimination adjusting circuit 13 will be described. Power is supplied to the load cell 1 without a weight.

First, the waste elimination adjusting circuit 13 is adjusted. That is, while confirming the level of the output signal (measurement signal) e ′ of the gain adjusting circuit 15, this output signal e ′
The dip-switch 32 of the waste elimination adjustment circuit 13 is turned on to make a rough adjustment so that the level of the same becomes "0", and then the variable resistor 33 is changed.

The computer 21 recognizes the digital signal f = 0 as having a metric value of zero. Place a weighing weight on the balance. Then, the gain adjusting circuit 15 is adjusted. That is, the level of the output signal e ′ of the gain adjusting circuit 15 is adjusted so that the output signal e ′ of the gain adjusting circuit 15 when the weight of the weighing is placed becomes equal to or lower than the upper limit value of the input signal of the A / D converter 16. While checking, the dip-switch 32 of the gain adjustment circuit 15
To adjust.

Assuming that the adjusted digital signal is f = β, the computer 21 recognizes β as a weighing.

[0012]

However, even if the gains of the conventional gain adjustment circuit 15 and the waste elimination adjustment circuit 13 are adjusted in this way, the zero point ( There is a problem that an error occurs in the A / D conversion value when the weight is not placed) and the span β (measurement value output from the gain adjusting circuit 15 for the weight), and accurate weighing cannot be performed. Further, there is a problem that the temperature characteristics of the zero point and the span change every time the gain is changed. Further, in order to form a circuit of the analog circuit section A so as not to be influenced by temperature, for example, in the above resistors R _s and R _f , a high quality and expensive resistor whose resistance value does not vary depending on temperature is used. There is a problem that it is necessary to select it and the cost increases.

The present invention is intended to solve such a problem, and it is possible to use a component in which various amounts vary depending on temperature, and to use an electronic scale that enables accurate weighing without being affected by temperature changes. It is an object of the present invention to provide a temperature characteristic correction method.

[0014]

In order to achieve the above object, a method for correcting temperature characteristics of an electronic scale according to the present invention has a load cell as means for detecting a scale, and a subtracter is wasteful from a load detection signal of the load cell. The analog circuit in an electronic scale having an analog circuit section for subtracting the useless erase signal adjusted in the erase adjusting circuit, adjusting the subtracted signal in the gain adjusting circuit, converting the subtracted signal into a digital signal and outputting the digital signal to the computer. A method for correcting temperature characteristics of a part, wherein the analog circuit part is provided with a temperature sensor for detecting a temperature of the circuit part, and the load detection signal corresponding to a zero point is input at least at two predetermined temperatures to input the waste signal. The output signal of the gain adjustment circuit is stored as zero point information for each gain of the eye elimination adjustment circuit and the gain adjustment circuit, and And the load detection signal corresponding to the weighing is input and for each gain of the gain adjusting circuit, the difference between the zero point of the gain adjusting circuit and the output signal corresponding to the weighing and the zero point information is stored as span information, and the temperature is stored. The temperature signal detected by the sensor is stored as temperature information, the temperature coefficient of the zero point is obtained from at least two zero point information and temperature information for each gain of the waste elimination adjustment circuit and the gain adjustment circuit, and the gain adjustment circuit is obtained. For each gain, the temperature coefficient of the span is obtained from at least two pieces of the span information and the temperature information, and the actual temperature information detected by the temperature sensor and the gain of the waste elimination adjusting circuit and the gain adjusting circuit at the time of actual weighing. The zero point is corrected from the temperature coefficient of the zero point according to the gain of the It is characterized in that for correcting the span from the temperature coefficient of the.

[0015]

According to the above method, the temperature coefficient of the zero point and the temperature coefficient of the span are obtained in advance for each gain, and at the time of actual measurement,
Based on the temperature coefficient of the zero point and the temperature coefficient of the span corresponding to the selected gain, the zero point is corrected by the actual temperature information detected by the temperature sensor, and the span is corrected, so that an accurate measured value is obtained. Therefore, for example, a resistor whose resistance value varies depending on temperature can be used in the analog circuit portion, an inexpensive resistor can be used, and the cost of the analog circuit portion can be reduced.

[0016]

An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the same components as those of the conventional example shown in FIG.

FIG. 1 is a circuit configuration diagram of an electronic balance using the temperature characteristic correction method of the present invention. As shown in the figure, in the analog circuit portion A ′, instead of the conventional waste elimination adjustment circuit 13, a first selection input terminal from a computer 41 described later is provided.
A waste elimination adjusting circuit 43 which inputs a waste elimination selection signal g via 42, adjusts the gain by an analog switch (not shown), and outputs a waste elimination signal d corresponding to the waste of the balance is Provided and further conventional gain adjustment circuit
Instead of 15, the gain selection signal h is input from the computer 41 via the second selection input terminal 44, the gain is adjusted by an analog switch (not shown), the weighing signal e is adjusted, and the weighing signal e ′ is adjusted. A gain adjustment circuit 45 for outputting is provided.

Further, a temperature sensor 50 for directly detecting the temperature of the analog circuit portion A'is provided, and the temperature detection signal k of the temperature sensor 50 is converted into a digital signal m to convert it to the computer 41.
An A / D converter 52 for outputting to the output terminal 51 is provided.

A method for correcting the temperature characteristic of the electronic scale, a method for adjusting the gain of the waste elimination adjusting circuit 43 and the gain adjusting circuit 45, and an actual measuring method by the computer 41 will be described with reference to the flowchart of FIG. [Step-1] First, put the analog substrate A'in the constant temperature bath, connect a dummy cell instead of the load cell 1 to supply power, and input a temporary load detection signal a and voltage signal b to the analog substrate A '. Let It is set so that the output of the dummy cell becomes "0". As a result, the output signal of the gain adjusting circuit 45, that is, the zero-point signal e ′ is converted into the digital signal f in the A / D converter 16 and input to the computer 41. For this digital signal f, the preamplifier 1
1, reference amplifier 12, waste elimination adjustment circuit 43, subtractor 14,
And the temperature characteristics of the components of the gain adjustment circuit 45 appear in combination. The temperature characteristic of the zero point of the A / D converter 16 is small and can be ignored. [Step-2] Gain adjustment signal h to gain adjustment circuit 45
Is output, and the gain is adjusted to G _G 1 by an analog switch (not shown). Then, the temperature of the constant temperature bath is set to −5 ° C., a waste elimination selecting signal g is output to the waste elimination adjusting circuit 43, and the gain is adjusted to G _M 1 by an analog switch (not shown). Next, the A / D converted value (digital signal f) at this time is input to the computer 41 and stored as Z11 (-5). Then, set the gain to G _M 2,
G _M 3 and G _M 4 are selected in order, and the A / D converted values at that time are input to the computer 41 and stored as Z12 (-5), Z13 (-5), and Z14 (-5). Also, the temperature sensor
The A / D conversion value T (-5) of 50 temperature detection signals k is input and stored.

Next, the gain of the gain adjusting circuit 45 is set to G
_G 2, _{G G} 3, adjusted to G _G 4, the gain of each, G _M 1 gain of waste th erasure adjustment circuit 43, G _M
The digital signal f of 2, G _M 3 and G _M 4 is input to the computer 41 and stored therein. [Step-3] The temperature of the constant temperature bath is set to 20 ° C., and the same operation as Step-2 is repeated. [Step-4] The temperature of the constant temperature bath is set to 45 ° C., and the same operation as Step-2 is repeated.

The stored results are shown in Tables 1 to 4.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

[Step-5] A waste elimination selecting signal g is output to the waste elimination adjusting circuit 43, and the gain is adjusted to G _M 1 by an analog switch (not shown). Then, the temperature of the constant temperature bath is set to -5 ° C, and the gain adjustment circuit 45
The gain selection signal h is output to and the gain is adjusted to G _G 1 by an analog switch (not shown).

First, the output of the dummy cell is adjusted to "0", the digital signal f at this time is input to the computer 41 as α (= Z11 (-5)), and then the dummy cell The output is adjusted so as to be substantially the same as when the weight for weighing is placed, and the digital signal f at this time is input to the computer 41 as β, (β-α) is calculated, and the span value G1 (-5) Is stored in the computer 41 as Then, similarly, the gains are changed to G _G 2, G _G 3, G
Select the _G 4 and sequentially, G2 to measure the span value in each case (-5), G3 (-5) , stored as G4 (-5). Further, the count value T (-5) of the temperature detection signal k of the temperature sensor 50 is input and stored. Span value G1
(-5), G2 (-5), G3 (-5), G4 (-5)
, The temperature characteristics of the sensitivity (gain) of each part of the analog circuit part A ′ appear in combination. [Step-6] The temperature of the constant temperature bath is set to 20 [deg.] C., and the same operation as Step-5 is repeated. [Step-7] The temperature of the constant temperature bath is set to 45 [deg.] C., and the same operation as Step-5 is repeated.

Table 5 shows the stored results.

[0029]

[Table 5]

[Step-8] Next, from the measured values obtained in Table 1 above, when the gain of the gain adjusting circuit 45 is G _G 1, the respective gains G _M 1, G _M 2, G _M 3, G each _M 4, less than 20 ° C., the temperature coefficient of more than zero Z11 (L), Z
11 (H), Z12 (L), Z12 (H), Z13 (L), Z13
(H), Z14 (L), Z14 (H) are calculated by the following formula and stored.

Z11 (L) = {Z11 (20) -Z11 (-
5)} / {T (20) -T (-5)} Z11 (H) = {Z11 (45) -Z11 (20)} / {T
(45) -T (20)} Z12 (L) = {Z12 (20) -Z12 (-5)} / {T
(20) -T (-5)} Z12 (H) = {Z12 (45) -Z12 (20)} / {T
(45) -T (20)} Z13 (L) = {Z13 (20) -Z13 (-5)} / {T
(20) -T (-5)} Z13 (H) = {Z13 (45) -Z13 (20)} / {T
(45) -T (20)} Z14 (L) = {Z14 (20) -Z14 (-5)} / {T
(20) -T (-5)} Z14 (H) = {Z14 (45) -Z14 (20)} / {T
(45) −T (20)} Similarly, the gain of the gain adjustment circuit 45 is G _G 2, G _G 3,
From the measured values was also determined in the above Tables 2 4 for the case of G _G 4, each gain _{G M 1, G M 2,} G M 3, each G _M 4,
Temperature coefficient Z21 (L) to Z24 of zero point of less than 20 ℃
(H), Z31 (L) to Z34 (H), Z41 (L) to Z44
(H) is calculated by the following formula and stored.

Z21 (L) = {Z21 (20) -Z21 (-
5)} / {T (20) -T (-5)} Z21 (H) = {Z21 (45) -Z21 (20)} / {T
(45) -T (20)} Z22 (L) = {Z22 (20) -Z22 (-5)} / {T
(20) -T (-5)} Z22 (H) = {Z22 (45) -Z22 (20)} / {T
(45) -T (20)} Z23 (L) = {Z23 (20) -Z23 (-5)} / {T
(20) -T (-5)} Z23 (H) = {Z23 (45) -Z23 (20)} / {T
(45) -T (20)} Z24 (L) = {Z24 (20) -Z24 (-5)} / {T
(20) -T (-5)} Z24 (H) = {Z24 (45) -Z24 (20)} / {T
(45) -T (20)} Z31 (L) = {Z31 (20) -Z31 (-5)} / {T
(20) -T (-5)} Z31 (H) = {Z31 (45) -Z31 (20)} / {T
(45) -T (20)} Z32 (L) = {Z32 (20) -Z32 (-5)} / {T
(20) -T (-5)} Z32 (H) = {Z32 (45) -Z32 (20)} / {T
(45) -T (20)} Z33 (L) = {Z33 (20) -Z33 (-5)} / {T
(20) -T (-5)} Z33 (H) = {Z33 (45) -Z33 (20)} / {T
(45) -T (20)} Z34 (L) = {Z34 (20) -Z34 (-5)} / {T
(20) -T (-5)} Z34 (H) = {Z34 (45) -Z34 (20)} / {T
(45) -T (20)} Z41 (L) = {Z41 (20) -Z41 (-5)} / {T
(20) -T (-5)} Z41 (H) = {Z41 (45) -Z41 (20)} / {T
(45) -T (20)} Z42 (L) = {Z42 (20) -Z42 (-5)} / {T
(20) -T (-5)} Z42 (H) = {Z42 (45) -Z42 (20)} / {T
(45) -T (20)} Z43 (L) = {Z43 (20) -Z43 (-5)} / {T
(20) -T (-5)} Z43 (H) = {Z43 (45) -Z43 (20)} / {T
(45) -T (20)} Z44 (L) = {Z44 (20) -Z44 (-5)} / {T
(20) -T (-5)} Z44 (H) = {Z44 (45) -Z44 (20)} / {T
(45) -T (20)} [Step-9] Next, from the measured values obtained in Table 2 above,
20 ° C for each gain G _G 1, G _G 2, G _G 3, G _G 4
Temperature coefficient G1 (L), G1 of less than or more than
(H), G2 (L), G2 (H), G3 (L), G3
(H), G4 (L), G4 (H) are calculated by the following formulas and stored.

G1 (L) = {G1 (20) -G1 (-
5)} / {T (20) -T (-5)} G1 (H) = {G1 (45) -G1 (20)} / {T
(45) -T (20)} G2 (L) = {G2 (20) -G2 (-5)} / {T
(20) -T (-5)} G2 (H) = {G2 (45) -G2 (20)} / {T
(45) -T (20)} G3 (L) = {G3 (20) -G3 (-5)} / {T
(20) -T (-5)} G3 (H) = {G3 (45) -G3 (20)} / {T
(45) -T (20)} G4 (L) = {G4 (20) -G4 (-5)} / {T
(20) -T (-5)} G4 (H) = {G4 (45) -G4 (20)} / {T
(45) -T (20)} [Step-10] Next, the analog board portion A'is incorporated into an actual electronic scale, the load cell 1 is connected and power is supplied, and the actual load detection signal a and voltage signal b. To enter. [Step-11] Next, enter the following items.

1. Applied voltage V (v) of the load cell 1, 2. Rated output L (mv / v) of load cell 1, 2. Rated capacity F (kgf) of load cell 1, 4. 4. Number of load cells 1 connected in parallel N, 5. 5. Weight of electronic scale W (kg), 6. 6. Waste of electronic scale Z (kg), 7. 7. Reference voltage X (v) of A / D converter 16, 8. Full scale S of A / D converter 16, 9. Gain of preamplifier 11 G _P (times), 10. Allowable value of zero of balance J 11. Scale reference scale K 12. Gain G selectable by the waste elimination adjustment circuit 43
_M (times), 13. The gain adjustment circuit 45 selectable gain G _G (fold) [Step -12 Next, calculates the gain G _G of the gain adjustment circuit 45 satisfies the following formula (1).

V · L · W / (F · N) · _GP · S / X · G _G ≦ K (1) The above equation (1) is the maximum A / D conversion value ( Within the reference scale K).

For example, V = 12v, L = 2mv / v, F
= 120 kgf, N = 1, W = 50 kg, X = 2v, S = 10
When 0000, G _P = 100 times and K = 60,000, the gain G _G ≦ 1.20 is obtained. [Step -13] selecting a gain G _G greatest gain adjustment circuit 45 which satisfies the above equation (1).

For example, G _G 1 = 1.00, G _G 2 = 1.40,
If G _G 3 = 1.96 and G _G 4 = 2.74 are selectable, the gain G _G 1 = 1.00 is selected. [Step-14] The gain selection signal h of the selected gain G _G 1 is output to the gain adjustment circuit 45. The gain is adjusted in the gain adjusting circuit 45 by the gain selection signal h. [Step -15] Further, by calculating the conversion value of the A / D converter 16 for the weighing W by the gain G _G selected and stored. Now, the calculated value on the left side of the equation (1) is "50000", and the A / D converted value for the weight W is "50000".
Therefore, thereafter, the computer 41 causes the digital signal f
Recognize the increment "50000" as the weight (W = 50 kg).

[0038] By the above step -12～15, reference scale K (= 60000) maximum A / D conversion value in which the selection of the gain G _G of the gain adjustment circuit 45 outputs to the computer 41 (= 50000) are obtained . [Step-16] In the selected gain G _G ,
The gain G _M of the waste adjustment circuit 43 that satisfies the following equation (2) is calculated.

The absolute value {V · L · Z / ( F · N) · G P · S / X · G G -X · G M · S / X · G G} ≦ J ... (2) (2) The formula adjusts the gain G _M of the waste adjustment circuit 43 so that the absolute value of the A / D converted value (digital signal f) without the weight is within the allowable value J.

When G _G = 1.00, for example, Z = 42k
When g and J = 10000, 0.32 ≦ gain G _M ≦ 0.52 is obtained. [Step-17] Select the gain G _M of the waste adjustment circuit 43 that satisfies the above expression (2) and minimizes the left side of the expression (2).

For example, G _M 1 = 0.10, G _M 2 = 0.30,
If G _M 3 = 0.50 and G _M 4 = 0.70 are selectable, then the gain G _M 3 = 0.50 is selected. [Step-18] The waste elimination selecting signal g of the selected gain G _M 3 is output to the waste elimination adjusting circuit 43. The gain elimination adjustment circuit 43 adjusts the gain in accordance with this elimination elimination signal g. [Step-19] Further, the bias value of the zero point by the selected gain G _M is calculated and stored as the value of the zero point.
Now, the calculated value on the left side of equation (2) is "absolute value (-8000)".
Therefore, the A / D converted value for the zero point is "-8000". Therefore, when the computer 41 inputs "-8000" as the digital signal f, it recognizes the measured value as 0 kg.

Thereafter, the computer 41 causes the A / D converted value "-".
8000-42000 (= -8000 + 50000) "to" 0-50kg "
Will be recognized. By the above steps -16 to 19,
Selected gain G_GIn the state where the weight is not placed
The target of the waste adjustment circuit that minimizes the absolute value of the A / D conversion value.
In G_MIs selected. [Step-20] The gain adjustment circuit 45 selected above
In G_GAnd the gain G of the waste adjustment circuit 43 _MOn the basis of,
Select the temperature coefficient of zero and the temperature coefficient of span.

As the gain G _G of the gain adjusting circuit 45, G _G
1. Since G _M 3 is selected as the gain G _M of the waste adjustment circuit 43, the temperature coefficient of the zero point is Z13 (L), Z
13 (H) is selected and G1 is used as the temperature coefficient of span.
(L) and G1 (H) are selected. [Step-21] From the temperature coefficient of the selected zero point and the input A / D converted value T (t) of the current temperature t ° C. of the analog circuit section A ′, the zero point Z measured without the weight is set.
1 (t) is corrected by the following formula. Let Z (t) be the metric value of the corrected zero point.

When T (t) <T (20), Z (t) = Z1 (t) + Z13 (L)  {T (20) -T
(T)} When T (t) ≧ T (20), Z (t) = Z1 (t) −Z13 (H) · {T (t) −T
(20)} [Step-22] From the temperature coefficient of the selected span and the A / D conversion value T (t) of the input current temperature t ° C. of the analog circuit section A ′, the span measurement value G1 (t) {= Metric value (digital signal f of A / D converter 16) -Z1 (t)}
Is corrected by the following formula. The corrected measured value is G (t)
And

When T (t) <T (20), G (t) = G1 (t) + G1 (L)  {T (20) -T
(T)} When T (t) ≧ T (20), G (t) = G1 (t) −G1 (H) · {T (t) −T
(20)} [Step-23] The actual measured value Q (kg) is calculated by the following equation.

Q = G (t) / 50000 · 50 (= weighing W) (kg) As described above, the zero point is corrected by the actual temperature of the analog circuit unit A ′ directly obtained by the temperature sensor 50, and the span is By being corrected, a more accurate measurement value Q can be obtained. Therefore, it is possible to use, as the components forming the analog circuit unit A ′, components whose amounts vary depending on the temperature, inexpensive components can be used, and the cost can be reduced. Further, even if the gain G _G of the gain adjusting circuit 45 and the gain G _M of the waste adjusting circuit 43 are changed, by selecting the temperature coefficient according to the gain, the error due to the gain change can be avoided, and the accurate weighing can be performed. Value Q
Can be obtained.

[0047]

As described above, according to the present invention, the temperature coefficient of the zero point and the temperature coefficient of the span are obtained in advance, and at the time of actual measurement, the temperature sensor is based on the temperature coefficient of the zero point and the temperature coefficient of the span. An accurate measured value can be obtained by correcting the zero point and the span by the actual temperature information detected by. Therefore, it is possible to use, as the components forming the analog circuit section, components whose amounts vary depending on temperature, inexpensive components can be used, and the cost can be reduced. Further, even if the gain of the circuit is changed, by selecting the temperature coefficient according to the gain, the error due to the gain change can be avoided and an accurate measured value can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an electronic balance using a temperature characteristic correction method of the present invention.

FIG. 2 is a flowchart of the electronic scale.

FIG. 3 is a circuit configuration diagram of a conventional electronic scale.

FIG. 4 is a circuit configuration diagram of a conventional waste elimination control circuit of an electronic scale.

[Explanation of symbols]

 1 Load cell 11 Preamplifier 12 Reference amplifier 14 Subtractor 16,52 Analog-digital converter 41 Computer 43 Unnecessary erasure adjustment circuit 45 Gain adjustment circuit 50 Temperature sensor A'Analog circuit section a, a 'Load detection signal b Voltage signal c Reference Voltage signal d Waste elimination signal e, e'Weighing signal f Digital signal g Waste elimination selection signal h Gain selection signal k Temperature detection signal m Digital signal

Claims (1)

[Claims] 1. A load cell as means for detecting a balance, wherein a subtractor subtracts a waste elimination signal adjusted in a waste elimination adjusting circuit from a load detection signal of the load cell, and the subtraction signal is applied in a gain adjusting circuit. A method for correcting temperature characteristics of an analog circuit section in an electronic scale having an analog circuit section that is adjusted, converted into a digital signal and output to a computer, wherein the analog circuit section detects the temperature of the circuit section. Temperature sensor is provided, and at least at two predetermined temperatures, the load detection signal corresponding to the zero point is input, and the output signal of the gain adjustment circuit is set as zero point information for each gain of the waste elimination adjustment circuit and the gain adjustment circuit. For each gain of the gain adjustment circuit by inputting the load detection signal corresponding to the zero point and the weighing amount. The difference between the output signal corresponding to the zero point and the weighing of the gain adjustment circuit and the zero point information is stored as span information, the temperature signal detected by the temperature sensor is stored as temperature information, and the gain of the waste elimination adjustment circuit is stored. Temperature coefficient of the zero point is obtained from at least two pieces of the zero point information and the temperature information for each gain of the gain adjustment circuit, and a temperature coefficient of the span is obtained from at least two pieces of the span information and the temperature information for each gain of the gain adjustment circuit. At the time of actual measurement, the zero point is corrected from the actual temperature information detected by the temperature sensor, the gain of the waste elimination adjusting circuit and the temperature coefficient of the zero point according to the gain of the gain adjusting circuit, and the actual temperature information is obtained. And a temperature coefficient of the span according to the gain of the gain adjusting circuit, the span is corrected, and the temperature characteristic of the electronic balance is characterized. Sex correction method.