JPH0114896Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electronic weighing machine using a load cell as a load conversion element.

Load cells are relatively easy to install due to their wide flexibility in mounting sensing mechanisms, and are often used in modern electronic weighing machines due to their small size. When a load cell is overloaded, mechanical deformation causes the zero point of the weighing machine to shift or the load cell to break down. They are used by being equipped with an overload detection device to detect when an overload or a load near the rated value is applied.

However, conventional overload detection devices simply compare the reference setting voltage level corresponding to the rated load of the load cell and the load cell output voltage level. Although it is possible to detect this overload condition, it is possible to detect this overload condition, but it is not possible to detect the impact load that is applied when the object to be weighed is placed on the tray etc. At present, this cannot be detected. As a result, problems arise in that weighing is carried out without knowing the danger of zero point shift and failure of the weighing machine due to impact loads exceeding the rated value. Furthermore, since the impact load has a fast propagation speed, it is very difficult to absorb it by a load cell mounting structure using a cushioning material or the like, and the cost becomes high.

Therefore, the present invention has been made to avoid the above-mentioned problems, and is an electronic type characterized in that an overload detection device is provided with a peak detection section so as to be able to detect that the impact load is applied. The company provides weighing machines.

An embodiment of the present invention will be described below based on the drawings.

FIG. 1 shows the configuration of an electronic weighing machine according to the present invention, where 1 is a strain gauge type load cell, 2 is an amplifier that amplifies the output of the load cell 1, 3 is an analog-to-digital converter that converts the output of the load cell 1, and 4 is an analog-to-digital converter that converts the output of the load cell 1 into digital. The calculation device performs weighting processing to make the digitally converted weighing information (Dg) suitable for displaying as a weight value, and the weighing information (Dg)
processing using other information. 5 is a display unit that displays the processing results of the arithmetic unit 4; Reference numeral 6 denotes a low-pass filter for removing flickering in the display by the display unit 5. Reference numeral 7 denotes an overload detection device having a peak detection function, which is constructed as shown in FIG. 8 is a noise removal filter, and 9 is a peak detector, which holds the peak value of the output voltage of the amplifier 2 via the filter 8. 10 is a comparator that outputs the output voltage level of peak detector 9.
By comparing Vs with a reference setting voltage level Vr according to the rating of the load cell 1, an abnormal situation of Vs>Vr or VsVr is detected. Note that the specific configuration of the peak detector 9 is well known, so a description thereof will be omitted.

In FIG. 1, reference numeral 11 denotes an alarm means controlled by the output of the overload detection device 7. When the comparator 10 detects an abnormal situation, the alarm means 11 generates an alarm sound, sounds a predetermined item, or lights a lamp, etc. The user is notified by blinking the element, etc. Note that the noise removal filter 8 is appropriately interposed as necessary.

Because it is constructed in this way, it can not only be used when an overload exceeding the rating is applied to the load cell 1 on a regular basis, but also overload caused by an impact load applied when a heavy object to be weighed is loaded onto the weighing machine. The overload detection device 7 detects dangerous operations that may lead to malfunctions such as shifting of the zero point of a scale using a load cell or destruction, thereby making it possible to prevent such dangerous operations from occurring.

As explained above, according to the present invention, overload acting on the load cell can be detected not only during static loads but also during impact loads. Therefore, when an abnormal situation occurs, it can be detected immediately and accurate weighing can be carried out. It is possible to implement the method and improve operability.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a block diagram of an electronic weighing machine, and FIG. 2 is a block diagram of an overload detection device. DESCRIPTION OF SYMBOLS 1... Load cell, 7... Overload detection device, 8... Noise removal part, 9... Peak detector, 10... Comparator, 11... Alarm means.

Claims (1)

[Scope of utility model registration request] This is an overload detection device for an electronic weighing machine that uses a load cell as a load converter, and includes a peak detector that holds the peak value of the load cell output voltage, and a reference setting voltage level that is set according to the rated load value of the load cell. 1. An overload detection device for an electronic weighing machine, comprising: a comparator for comparing the output voltage level of the peak detector with an output voltage level of the peak detector; and an alarm means controlled by the output of the comparator.