JPH0228809B2 - ZERO * TORATSU KINGUKAIRO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a zero tracking circuit for an electronic scale, and an object thereof is to provide a zero tracking circuit that can display zero tracking even during tare compensation.

Conventionally, in electronic scales, weight data is corrected using a zero point correction value, and tare weight correction is performed by further subtracting a tare amount. Figure 1 shows this conventional configuration, with 1
2 is a load cell that converts the load G into an electric signal, 2 is an A/D converter, 3 is a zero point correction section, and a first memory 4 that stores a zero point correction value, and the contents of this first memory 4 are subtracted from the above. and a first arithmetic unit 5 whose minuend is the weighing data _D1 from the A/D converter 2. Reference numeral 6 denotes a tare correction section, which includes a second memory 7 for storing the tare amount, and the weight data D ₂ which subtracts the contents of the second memory 7 and outputs the zero point correction section 3.
and a second arithmetic unit 8 whose minuend is . Reference numeral 9 denotes a determination unit that determines the necessity of zero tracking, which monitors the weight data _D2 output from the zero point correction unit 3 and determines whether this weight value data is near the zero point of the weighing and the amount of change per unit time. is less than a predetermined value, it is determined that a zero point fluctuation has occurred, and a tracking instruction _P1 is output. The first memory 4 stores the tracking instruction _P1 of the determination unit 9 input via the OR gate 10 or an external tracking instruction.
P ₂ is updated to the latest weighing data D ₁ of the A/D converter 2 output, and the second
The memory 7 is updated to the latest data D2 output from the first calculation section ₅ every time an external tare weight subtraction instruction _P3 is given. 11 and 12 are a tare display section and a weight display section.

With this configuration, when a tare with a weight of A gram is placed and the contents of the second memory 7 are updated to A gram, the tare is corrected and the weight display section 12
The display changes from A-gram to zero-gram. However, in this state, the weight data D ₁ output from the zero point correction section 3 is an A-gram [weight value that is not near the zero point]
Therefore, even if the zero point fluctuation of Δa gram occurs and this weight value data fluctuates to (A+Δa) gram, the determination section 9 does not issue the tracking instruction _P1 . Therefore, the first memory 4 is not updated, and the zero point fluctuation of the Δa gram remains unchanged in the weight display section 1.
2, and the current situation is that the zero point display after tare correction cannot be stably maintained. Therefore, as shown in FIG.
It is often thought that the above problem can be avoided if the configuration is configured to monitor D ₃ and give tracking instruction P ₁ to the first memory 4, but in this case, the content of the first memory 4 is (A+Δa ) grams, and the weighing data of the zero point correction section 3 output
Although D ₁ becomes zero grams, the weighing data D ₃ output from the tare correction section 6 changes to -A grams. Even with the configuration shown in Fig. 2, the current situation cannot be improved. Can not.

The outline of the present invention is that the determination section 9 monitors the weight value data after tare correction and adds the tare amount A-gram written in the second memory 7 to the predetermined weight data. An embodiment of the present invention which avoids the problems will be described below with reference to FIG. Components having the same functions as those in FIG. 1 are designated by the same reference numerals and their explanations will be omitted.

FIG. 3 shows an electronic scale equipped with a zero tracking circuit according to the present invention, and 13 is a third calculation section interposed between the zero point correction section 3 and the tare correction section 6, and the output of the zero point correction section 3 is The tare amount written in the second memory 7 is added to the weighing data _D2 . Further, the determination unit 9 monitors the weighing data D ₃ as shown in FIG.
In the rewrite signal system, the first memory 4 and the second memory 7 are updated each time an external tare instruction P ₃ is given, and the first memory 4 is also updated depending on the tracking instruction P ₁ of the determination unit 9. Connected to be updated.

With this configuration, when the contents of the first and second memories 4 and 7, that is, the zero point correction value Z and the tare weight correction value T are both zero grams, and a tare weight A gram is placed, the weighing data D ₁ , Both D ₂ and D ₂ ′ are A
gram, and the weighing data _D3 is also an A gram. If external tare instruction P ₃ is given in this state, the second
The memory 7 of is updated and the tare correction value T changes from zero gram to A gram, and then the first memory 4 is also updated via the OR gate 10 and the zero point correction value Z changes from zero gram to A gram. By updating the first and second memories 4 and 7, the weighing data
D ₂ is A-A = zero grams, weighing data D ₂ ' is zero + A
= A gram, weight data D ₃ becomes A-A = zero gram, and the tare correction is completed. Therefore, if the weighing data D ₁ changes by A+Δa after that, the weighing data D ₃ changes from zero to Δa grams, but the determination section 9 that monitors this slight change immediately issues a tracking instruction P. ₁ , the contents of the first memory 4 are updated from A to A+Δa, the weighing data D ₂ becomes zero grams, the weighing data D ₂ ' becomes A grams, and after tare correction for the minute change Δa. The weighing data D ₃ of is maintained at zero grams.

As explained above, according to the zero tracking circuit of the present invention, in an electronic scale that corrects weighing data with a zero point correction value and further subtracts the tare amount to perform tare correction, the weighing data after tare correction can be monitored. A determination means for determining the necessity of zero tracking is provided, and a calculation means for adding the tare amount to the weighing data after zero point correction is provided between the zero point correction section and the tare correction section. At the time of detection, instruct the tare correction section to update the tare amount correction value, instruct the zero point correction section to update the zero point amount correction value, and update the zero point correction value when the determination means determines that tracking is necessary. Since a rewriting means for instructing is provided, the weight display during the weighing standby period can be maintained at zero even during tare compensation.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional electronic scale, FIG. 2 is an explanatory diagram of the present invention, and FIG. 3 is a block diagram of an electronic scale showing an embodiment of the zero tracking circuit of the present invention. 1...Load cell, 2...A/D converter,
3... Zero point correction section, 4... First memory, 5...
1st calculation unit, 6...Tare correction unit, 7...Second memory, 8...Second calculation unit, 9...Judgment unit [judgment means], 11...Tare display unit, 12... Weight display section, 13...Third calculation section [calculation means], P ₁ ...
...Tracking instruction, P ₂ ...External tracking instruction, P ₃ ...External taring instruction.

Claims (1)

[Claims] 1. In an electronic scale that corrects weighing data with a zero point correction value and further subtracts the tare weight for tare correction, a determination means is provided to monitor the weighing data after tare correction and determine the necessity of zero tracking, A calculation means for adding the tare amount to the weighing data after zero point correction is provided between the zero point correction section and the tare correction section, and when a tare amount update instruction is detected, the tare correction section is configured to update the tare amount correction value. The zero tracking circuit is provided with rewriting means for instructing the zero point correction unit to update the zero point amount correction value and for instructing the zero point correction value to be updated when the determining means determines that tracking is necessary.