JPH0138501Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a scale equipped with a load detector such as a strain gauge type load cell.

Generally, in a scale using a strain gauge type load cell, the weight of the object to be weighed is determined by setting the output of the load cell in an unloaded state after an appropriate amount of time has elapsed after the power is turned on as the zero point. However, if the output of the load cell at this time is above the predetermined allowable upper limit, the measurable range will be narrowed, and if the output of the load cell is below the allowable lower limit due to forgetting to remove the rest device, measurement will not be possible. Variations in the output of the load cell caused measurement errors. Conventionally, when it is detected that the output of a load cell is outside the allowable range, there is a structure that holds the display of the weight, etc. and notifies that it is outside the allowable range (Japanese Patent Laid-Open No. 55-22141 Publication No.). However, with this method, it is not possible to determine whether the output of the load cell is larger than the allowable upper limit or smaller than the allowable lower limit, and it is not possible to promptly take measures against the abnormal state. Moreover, this method is completely unable to deal with the case where the output of the load cell fluctuates within the permissible range.

The purpose of this invention is to provide a scale that solves the above-mentioned problems.

This invention will be explained below based on one embodiment shown in the drawings. In Figure 1, 1 is a strain gauge type load cell, which generates an output in a no-load state with an applied operating voltage, and whose output changes when a load is applied by placing an article to be weighed on a tray. It is something. Reference numeral 2 denotes an analog-digital converter (hereinafter referred to as an A/D converter), which converts the analog output of the load cell 1 into a digital signal. Reference numeral 3 denotes an arithmetic circuit that calculates the deviation of the outputs of the load cell 1 in the no-load state and in the load-applied state, which are digitally converted by the A/D converter 2, respectively. Reference numeral 4 denotes a display unit which displays the calculated values of the calculation circuit 3 and the detection results of the abnormal state detection circuit 5, which will be described later, and is composed of five 7-segment displays 6a to 6e as shown in FIG. There is.

Reference numeral 5 denotes an abnormal state detection circuit, which has a comparison circuit 7 as shown in FIG. This comparison circuit 7 is
The digital signal from the A/D converter 2 is compared with a predetermined allowable upper limit value, and when the digital signal is larger, an output is generated. 8 is also a comparison circuit that compares the digital signal from the A/D converter 2 with a predetermined allowable lower limit value,
The digital signal is configured to generate an output when the digital signal is smaller. 9 is also a comparison circuit, A/
It is configured to generate an output when the digital signal of the D converter 2 and the value stored in the temporary storage register 10 do not match. Temporary memory register 10
is supplied so as to store the previous digital signal of the A/D converter 2, and to store the current digital signal of the A/D converter 2 when the power is turned on. These comparison circuits 7, 8, and 9 are configured to operate after a predetermined period of time has passed after the power is turned on. The output of the comparison circuit 7 is used to display H, the output of the comparison circuit 8 is L, and the output of the comparison circuit 9 is used to display U on the display 6e of the display section 4. Also,
The outputs of the comparison circuits 7, 8, and 9 are supplied to the OR circuit 11, and the output of the OR circuit 11 causes the display 6a of the display section 4 to display E and the displays 6b, 6c, and 6d to display "-". used for.

In the scale configured in this manner, if an abnormal condition occurs after a predetermined period of time has passed after the power is turned on, for example, if the digital signal of the A/D converter 2 is larger than the allowable upper limit, the comparator circuit 7 and the OR circuit 11 will output an output. Occur. As a result, the displays 6a to 6e of the display section 4
As shown in Figure 2, E-H are displayed in order,
It can be seen that the digital signal is greater than the allowable upper limit. Similarly, if the digital signal is below the allowable lower limit value in the initial state due to forgetting to remove the rest device, etc., the comparator circuit 8 and the OR circuit 11 generate outputs, and the displays 6a to 6e of the display section 4 display E-
L is displayed. Further, if the digital signal is unstable and does not match the previous digital signal stored in the temporary memory 10, the comparator 9 and the OR circuit 11 generate an output, and the display 6a of the display unit 4
EU is displayed in order from 6e to 6e.

If no abnormal condition has occurred after a predetermined period of time has elapsed since the power was turned on, 0 is displayed on each of the indicators 6a to 6e. At this time, when a load is applied to the load cell 1 by placing the article to be weighed on the tray, the arithmetic circuit 3 converts the digital signal of the A/D converter 2 in the no-load state and the A/D signal in the load application state. The deviation from the digital signal of section 2 is calculated, and the weight of the article to be weighed is displayed on display section 4 based on this calculation result.

In this scale, by providing an abnormal state detection circuit 5 composed of comparison circuits 7, 8, 9 and a temporary storage register 10, it is possible to detect whether the output of the load cell 1 is greater than the upper limit value or lower than the lower limit value. Not only small abnormal conditions but also changes in the output of the load cell can be immediately detected, so it is possible to prevent not only narrowing of the measurable range and inability to measure, but also measurement errors. Moreover, since the display 6e shows the type of abnormality (H, L, or U) depending on the detection result, you can immediately know what kind of abnormal condition is occurring by looking at this display. , can quickly respond to abnormal situations.

In the above embodiment, both the weight display and the abnormality display are performed on the display section 4, but the weight display section and the abnormality display section may be provided separately. Furthermore, the output of the OR circuit 11 causes the displays 6b and 6 of the display section 4 to
Although "-" was displayed on c and 6d, the comparator circuit 7,
You may also use the outputs of 8 and 9.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a scale equipped with an abnormal state display device according to this invention, FIG. 2 is a front view of the display device of the same scale, and FIG. 3 is a block diagram of an abnormality detection circuit used in the scale. 1...Load cell (load detector), 3...Arithmetic circuit, 4...Display section, 7, 8...Comparison circuit (tolerable range detection circuit), 9...Comparison circuit (fluctuation detection circuit).

Claims (1)

[Scope of utility model registration request] A load detector that generates an output in a no-load state and increases the output based on the application of a load, and a circuit that calculates a deviation between the output of the load detector in the no-load state and the output in the load application state. , a circuit that generates a fluctuation detection signal when detecting fluctuation in the output of the load detector in the no-load state, and a circuit that generates a fluctuation detection signal when the output of the load detector in the no-load state is lower than a predetermined upper limit a circuit that generates an upper limit exceedance detection signal when the
A circuit that generates a lower limit exceedance detection signal when the output of the load detector in the no-load state is smaller than a predetermined lower limit value, and a circuit that generates a lower limit exceedance detection signal in response to the fluctuation detection signal, and displays a display indicating output fluctuation in response to the above upper limit value. A scale equipped with an abnormal state display device, comprising: a display section that displays an indication that an upper limit value has been exceeded in response to an excess detection signal, and a display section that displays an indication that a lower limit value has been exceeded in response to the lower limit excess detection signal.