JPS63290922A - Body weight meter - Google Patents

Abstract

PURPOSE:To reduce the thickness and weight of a body weight meter and to reduce its space by providing a sensor which measures body weight, an electric signal processing part which converts its measurement signal into a display signal, and a display means, and using a nearly plate type electric sensor as said sensor. CONSTITUTION:Polymer films 1 where electrodes are printed are adhered to the top and reverse surfaces of the electric sensor 2 made of a conductive rubber sheet which various in electric resistance when applied with a force. Then, the electric signal processing part 3 which applies the output of the electric sensor 2 to the sheet and supplies the display signal to the body weight display part 4 and the body weight display part 4 which displays body weight with the output of the electric signal processing part 3 are fitted. A reference current I0 is supplied to the conductive rubber sheet 2 and the current voltage is passed through an operational amplifier and measured by an A/D converter, whose output is displayed on the display part by a microprocessor MPU.

Description

[Detailed description of the invention] (Technical field) The present invention relates to weight scales.

(Background Art) Conventional weight scales are generally mechanical scales that use springs. This has the advantage of having a simple structure, but the scale is tall and heavy, so it has the disadvantage of requiring a large storage space.

(Objective of the Invention) The present invention has been proposed in order to improve the above-mentioned drawbacks, and it is an object of the present invention to provide a weight scale that is thin and light and does not take up much storage space.

(Disclosure of the Invention) In order to achieve the above object, the present invention provides an electrical sensor that is substantially plate-shaped and generates an output according to weight, and an electrical signal that inputs the output of the sensor and provides a display signal to a display means. The gist of the invention is a weight scale characterized by comprising a processing section and a display means for displaying weight based on the output from the electrical signal processing section.

Next, embodiments of the present invention will be described. It should be noted that the examples are merely illustrative, and within the scope of the spirit of the present invention,
Needless to say, various changes and improvements may be made.

FIG. 1 shows a first embodiment of the weight scale of the present invention.
In the figure, 1 is a polymer film, 2 is a part of the sensor, and 3
Reference numeral 4 indicates an electrical signal processing section, and 4 indicates a weight display section.

In this embodiment, a conductive rubber sheet is used for the sensor part 2, and a polymer film 1 with electrodes printed on the top and bottom of the conductive rubber sheet is used.
are arranged to form a sandwich-structured sheet. A weight scale is constructed by attaching an electric signal processing section 3 and a weight display section 4 to this sheet.

The operating principle of this scale will be explained. Conductive rubber sheets exhibit the characteristic that when force is applied to the sheet, the electrical resistance of the sheet decreases, and generally its characteristic curve is
It is as shown in the figure. In the figure, the horizontal axis is the load P,
The vertical axis shows the resistance R. Utilizing this property, the change in electrical resistance of the seat when a human body is placed on it is measured, converted to weight, and displayed. FIG. 2 shows a system block diagram of the electrical signal processing section 3 and the weight display section 4. In the figure, 1 is a polymer film, 2 is a part of the sensor, OP is an operational amplifier, 1 is an analog-to-digital converter, and MPU is a microprocessor unit. In this embodiment, a reference current I0 is applied to a conductive rubber sheet 2. The system measures the voltage at that time using an operational amplifier and a power converter, converts it into a resistance using an MPU, and then calculates and displays the weight using the characteristic curve shown in Figure 3.

In addition to this embodiment, the sheet may be any conductive material as long as it has a correlation between force and resistance and can be formed into a sheet shape.

Further, the signal processing section may also be of any type as long as it can measure resistance changes.

Next, a second embodiment will be described. This embodiment is shown in FIG. In the figure, 11 is an electrode, 12 is a piezoelectric ceramic sheet, 13 is a signal processing section, and 14 is a display section. To explain the principle of operation, generally when a piezoelectric ceramic is subjected to force, its thickness changes by δ, and this change generates a voltage. FIG. 6 shows the characteristics.

Therefore, it is sufficient to measure the voltage due to the change in force in the signal processing section 13, but since this voltage is generated only when the thickness changes, the voltage becomes zero once the deformation is stabilized. become. Therefore, it is sufficient to measure the voltage until the deformation becomes stable. However, the time course of the thickness change δ when measuring the body weight is as shown by the broken line in FIG. 7, and the accompanying voltage change is shown by the solid line.

This waveform differs depending on the impact when a person steps on it, but the voltage integrated along the time axis is constant depending on the body weight, so the body weight can be determined by converting that value. FIG. 5 is a block diagram of signal processing for measuring voltage using this principle.

In the figure, 11 is an electrode, 12 is a piezoelectric ceramic sheet, FET is a field effect transistor, and OP is an operational amplifier. In this example, voltage is applied to the gate of the FET through a low-pass filter consisting of resistor R1 and capacitor C1, and
The output voltage of the source-side resistor R2 is applied to the operational amplifier OP. The piezoelectric ceramic sheet of this 41st embodiment may be any material other than those whose main components are general lead titanate, lead zirconia acid, etc., as long as they exhibit similar properties.

Furthermore, any signal processing circuit that can measure voltage changes may be used.

(Effects of the Invention) According to the present invention, there is provided an electric sensor which is substantially plate-shaped and generates an output according to the weight of the scale, and the output of the sensor is inputted;
By including an electric signal processing section that provides a display signal to the display means, and a display means that displays the weight based on the output from the electric signal processing section, (a) the sensor part 2.12 of the scale can be arranged in a sheet form. The thickness can be reduced because it can be made into

(b) Since it is in sheet form, it can be folded or rolled up to reduce storage space.

(c) Part of the sensor is sheet-shaped and can be made lighter.

This has the effect of creating a low-height, lightweight scale such as the following.

[Brief explanation of drawings]

Fig. 1 shows the first embodiment of the present invention, Fig. 2 shows the signal processing section of the first embodiment, Fig. 3 shows the characteristic curve of conductive rubber, and Fig. 4 shows the second embodiment of the invention. , FIG. 5 shows the signal processing section of the second embodiment, FIG. 6 shows the characteristic curve of the piezoelectric ceramic, and FIG. 7 shows the deformation of the piezoelectric ceramic and the time change of voltage. DESCRIPTION OF SYMBOLS 1... Electrode, 2... Conductive rubber sheet, 3... Signal processing part, 4... Display part, 11... Electrode, 12...
・Piezoelectric ceramic sheet, 13...signal processing section, 1
4...Display section. Figure 4 Figure 5 Figure 8,'''- Figure 6 Figure 7

Claims (3)

[Claims] (1) An electrical sensor that is approximately plate-shaped and generates an output according to weight, an electrical signal processing unit that inputs the output of the sensor and provides a display signal to a display means, and an output from the electrical signal processing unit A weight scale characterized by comprising: display means for displaying weight. (2) The weight scale according to claim 1, which uses a conductive rubber sheet having electrodes on both sides as a sensor. (3) The weight scale according to claim 1, which uses a piezoelectric ceramic sheet having electrodes on both sides as a sensor.