JPS62284219A - Body weight meter - Google Patents

Abstract

PURPOSE:To easily the weight and thickness of a body weight meter by using pressure sensing conductive rubber as a sensor and detecting a load at the time of body weight measurement in terms of a resistance value. CONSTITUTION:The pressure sensing conductive rubber is used as a sensor 1 and an analog signal indicating variation in resistance value led out by this sensor part 1 is supplied to an analog signal amplifying circuit 2. A data decision circuit 4 decides the motion, accurate position, etc., of a human body on the measuring instrument and outputs an OK signal when all conditions are satisfied to hold the operation of an A/D converter, thereby making a numeral easy to read. The A/D converter circuit part 3 sends out a signal to a display device 6 on the basis of data held as mentioned above and the person to be weighed knows his or her weight accurately from the display. Thus, the pressure sensing conductive rubber is used as the sensor, so the body weight meter is reducible in size and weight.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a weight scale, and particularly to a weight needle suitable as a simple type for general home use.

[Prior art]

The weight needle measuring method has long since changed from the weight type to the spring type due to demands for easier reading and shorter measurement time. Along with this, the shape has also become more compact (flat) and lighter.

By the way, in recent years, home scales have become popular due to the above-mentioned simplification of weight measurement and increased awareness of health management on an individual basis.
Ease of handling is an issue.

That is, conventional household scales have a thickness of 50 mm to 7 mm.
It had a structure with a diameter of around 0 mm and a weight of 2 to 4 kg. However, the current state of the art is still insufficient for home use, and especially for home use, it is desirable to make the device lighter and more compact. For example, the above-mentioned weight is inconvenient when handled by children or when stored in a high position, and it is desired to be lighter and more compact when handled in the bathroom of a general household.

Also, regarding the installation location during measurement, it is desirable that the base can be used on soft materials such as tatami mats, jutan, foot towels, etc.

[Purpose of the invention]

The present invention has been made in view of these problems, and its purpose is to provide a weight scale that can be made thinner and lighter.

[Structure of the invention]

In order to achieve the above object, the present invention includes a pressure-sensitive conductive rubber sensor section that extracts the load of a weight scale as a change in the resistance value of the pressure-sensitive conductive rubber, a measurement circuit that generates an electric signal corresponding to the change in the resistance value, and a measurement circuit that generates an electric signal corresponding to the change in the resistance value. The gist thereof is to have an indicator section that indicates body weight using an electric signal.

The pressure-sensitive conductive rubber used in the present invention has conductive particles such as graphite particles and metal particles dispersed therein, as disclosed in, for example, JP-A-49-114798 and JP-A-53-79937. It is a rubber elastic body that exhibits a resistance value according to the amount of deformation due to a load, and the size of the measuring element can be made small, for example, with a side of several C1 and a thickness of several IIIL. Moreover, it is possible to convert it into an electrical quantity and measure the weight using a so-called hard electric circuit, but in combination with a microcomputer, it is possible to perform digital display, memory, comparison with standard weight, display,
By combining it with electronic sounds, etc., it is possible to make a variety of applications possible, such as commercialization for children.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIGS. 1 and 2 show the structure of a weight scale according to an embodiment of the present invention.

This weighing scale includes a sensor section made of pressure-sensitive conductive rubber disposed at the load level, a measuring circuit (conversion to electric quantity, amplification, digitization, and microcomputer control circuit), and a display section.

In FIG. 1, 1 is a pressure-sensitive conductive rubber sensor section, 2 is an analog signal amplification circuit, 3 is an A/D converter, 4 is a data determination circuit, 5 is a memory circuit, and 6 is a display section. As described above, the weight needle of this embodiment uses pressure-sensitive conductive rubber as a sensor and performs indication through electrical processing.

Here, first, the pressure-sensitive conductive rubber will be explained.

Pressure-sensitive conductive rubber can be adjusted to exhibit a resistance change within a certain range under a given load by selecting appropriate values for carbon particle diameter, dispersion density, etc., so it can be used as a load sensor, etc. In addition, it has excellent corrosion resistance, is relatively inexpensive, has a rubberized appearance, and is easy to handle.If it is held between electrodes, resistance can be easily measured.

A typical configuration for the above resistance measurement is a structure in which a small piece of pressure-sensitive conductive rubber in the form of a sheet is placed on an electrode with a lead wire attached, and a pressure-receiving electrode, also with a lead wire attached, is placed on top of it. .

As a method for obtaining pressure-sensitive conductive rubber, for example, a silicone rubber elastic body is used as the elastic body, and as disclosed in JP-A-53-79937, it is mixed with artificial WA fine particle rubber. It can be produced by a method of dispersion, or by a method of using fine nickel powder as disclosed in JP-A-49-114798.

The size of the pressure-sensitive conductive rubber is not particularly limited, but for example, one with a diameter of about 1 cm or about 1 cm x 1 am and a thickness of about 0.5 mm can be used.

Also, regarding the shape as a load capacity, the size is such that you can easily stand on it, for example, approximately 30C for adults.
IIX30C11, the total thickness of the load receiving plate, measuring part, and substrate can be approximately 10.

When examining the relationship between the center of gravity and the position of the feet on a large number of subjects, it was observed that there are individual differences in the movement of the center of gravity from side to side and back and forth.

Therefore, a simple structure is fine as long as it takes these points into account and provides stable values.

That is, FIG. 2(B) is a partially cutaway plan view of the weight scale according to the present embodiment, and FIG. 2(A) is a cross-sectional view taken along the line using a sensor by
The body weight is supported by a rubber plate. In the figure, 7 is a substrate (FRP), 8 is a rubber plate, 9 is a pressure-sensitive conductive rubber sensor part, and 10 is a load holder (FRP).
, 11 are voids. The rubber plate 8 is a normal rubber plate made of silicone material, for example. Regarding the thickness of the board 7, rubber plate 8, and load holder 10, for example, the board 7 is about 2 mm, the rubber plate 8 is 3III11, and the load holder 10 is about 2 mm.
It is 11111.

Furthermore, the void 11 is cut out to adjust the amount of deformation, since if the entire plate is made of rubber, the deformation due to body weight will be small when extracting the electrical resistance change due to compressive deformation of the pressure-sensitive conductive rubber. .

The foot shape shown in FIG. 2 is used to guide the subject to the position where the load receiver stands on the slope. Furthermore, various applications such as making this design into a figure that children like are possible.

Furthermore, in the example of Fig. 2, there is one sensor as mentioned above, but for more accurate measurements or when measuring heavy weights, for example, as shown in Fig. 3, each sensor is supported at four points. By outputting the added value of the detected values from the sensors as the detected weight value, it is possible to further reduce measurement errors due to the riding position of the subject. The sensor section of the present invention can also be supported at three points other than the above-mentioned one or other multi-point supports.

Regarding the sensor part 9, metal foils as electrodes are attached to both the upper and lower surfaces of the 0.5 mm pressure-sensitive conductive rubber, and lead wires are drawn out, and a spacer is provided between it and the load holder lO. I made it.

Note that an electric circuit including a one-chip microcomputer, etc. is housed in the housing of the display unit 6, and
2 is a battery case for power supply.

The analog signal amplification circuit 2 is supplied with an analog signal indicating a change in resistance value taken out by the sensor section 1 using such pressure-sensitive conductive rubber. Here, the signal is amplified, and the amplified signal is output after its curve is corrected so that the A/D converter can work more easily.

That is, this circuit section 2 includes a curve correction circuit, which converts the applied force into an electrical quantity that changes almost linearly.

Here, the Kerr resistance characteristics and linearization of pressure-sensitive conductive rubber will be described.

In pressure-sensitive conductive rubber, the relationship with resistance R is generally not linear.

Therefore, it is possible to measure by simply incorporating pressure-sensitive conductive rubber as a variable resistor into the base circuit and taking out the output from the collector of the transistor, but if you use this resistance value change characteristic as is, it will be difficult to handle electrically. Hateful. Therefore, the present inventor first developed a pressure-sensitive conductive rubber in order to achieve a linear relationship in a circuit that compresses and deforms the pressure-sensitive conductive rubber and converts force into an amount of electricity by utilizing changes in electrical resistance. An electrical resistance characteristic correction circuit was developed in which the connected electrodes were connected so as to give a signal representing the electrical resistance change to the circuit, and an FET was provided to take out the resistance change as an output. A patent has been applied for.

In other words, we focused on the fact that the drain current of an FET is approximately proportional to the square of the gate voltage, and found that the resistance of the pressure-sensitive conductive rubber described above is inversely proportional to approximately 1.8 to 1.9 power of the force applied to it. This cancels out the force and converts it into an amount of electricity that converts almost linearly to the force. Therefore, the pressure-sensitive conductive rubber is usually appropriately connected as a resistor to a circuit that applies voltage to the gate of the FET. Specifically, for example, a resistor is connected between the FET gate and the -B power supply, a resistor is connected between the FET gate and the drain, and the drain is connected to the 10B power supply. The source may be grounded through a resistor, and the configuration may be such that the output is obtained from the source of the FET.

If the characteristics are corrected in this way, the correspondence between the force and the output signal becomes almost a straight line, making it easy to use in various devices (in this embodiment, the circuit section 2 does not include such a curve correction circuit). I'm here.

The pressure applied to the pressure-sensitive conductive rubber in this way is extracted as a change in resistance value and amplified in the next signal amplification circuit, and this amplified signal is sent to the A/D converter (aJ). The curve is corrected and output.

Here, since various measurement errors will occur if the A/D converter is operated directly with this signal, a data judgment circuit 4 is provided. When measuring body weight, it takes 3 to 4 seconds for the deformation of the pressure-sensitive conductive rubber to stabilize. Also, it is difficult to read if the detected value fluctuates depending on the way the weight is applied, so it is better to step on the scale, estimate the value that stabilizes after a certain period of time, and output the detected value as an average value for the pulsating value. It's convenient.

For this reason, the data judgment circuit 4 is provided, and when the conditions are met by judging the movement and exact position of the person on the scale, it issues an OK signal and activates the A/D converter. It has a function to hold and make the numbers easier to read.

The A/D converter circuit section 3 sends a signal to the indicator 6 based on the data in the held state as described above,
The person to be measured can accurately know their weight from the display.

This circuit section 3 includes a control section having an arithmetic circuit and an indicator driver, and operates the signal from the analog signal amplification circuit section 2 to operate the indicator section.

The display unit 6 can use LED or LCD,
Indicate the weight numerically, as in this example.

Furthermore, various types of display can be used as the display, such as a digital or analog panel display, a sound display including synthesized speech, or a light display.

Next, the memory circuit 5 will be explained.

Traditional weight needles simply measure weight.

In other words, at present, it is a device that simply measures weights, and considering the recent improvement in health management awareness and the widespread use of household scales as described above, there is still room for improvement as a health management machine, especially as a scale for general household use. There is a lot of room for.

By the way, as mentioned above, this weight scale uses resistance change type pressure-sensitive conductive rubber as the ff1ffl sensor, and is not only thin and light, but also processes completely electrically, with memory capability and electric Easy to process.

From this point of view, this weight scale also has the following additional functions.

That is, the memory circuit 5 has the following three functions.

One of them is melody memory. This is because, as mentioned above, it takes several seconds for the weight applied to the weight hand to stabilize due to the creep characteristics of the sensor element itself. It also serves as a signal when the measurement is OK, and is very effective.

That is, for example, according to a program input in advance into the ROM, a melody will play as you ride, and once the melody stabilizes, the melody will stop, and as mentioned above, the circuit will hold the detected value and display your weight as a digital value in an easy-to-read state. It will be. This is a so-called weight checker, which allows the person being measured to confirm that the measurement is in progress, and at the same time, especially for children, it allows them to have fun while measuring their weight, and naturally motivates them to measure their weight. It is also possible to induce it to hold.

Another option is to take advantage of the fact that the electronic weight hand is relatively easy to memorize due to its structure, and is equipped with a memory function that allows you to read out your previous weight, etc. , by using RAM. Note that it is also easy to provide a calculation function so as to display the amount of change in body weight from the previous time.

Furthermore, another method is to input the average weight that can be determined from the height into the ROM in advance, and read out the difference between the average weight and the measured weight to perform health management.

Further, a household power source can be used as a power source for the weight needle, but a battery can be used to store data in the RAM. You may also use a solar battery.

FIG. 3 shows a modification of the embodiment shown in FIG. 1.

That is, this modification is configured so that when a person steps on the weight needle, a melody is played until the weighing result is displayed to indicate that the weight correction has been activated, and corresponds to the data judgment circuit 4. This is a modified version of the part that does.

In the figure, 13 is a comparator, 14 is a display 6
15 is a timer, 16 is a delay circuit, 17 is a hold circuit,
Reference numeral 18 denotes a judgment circuit for a hold circuit, and 19 denotes a sound generation circuit for notifying the person to be measured that weight measurement is in progress.In the case of this embodiment, the melody is configured to continue until the end of the measurement. The signal is output as sound from the speaker 20, and the comparator 13 is provided with an analog signal from an amplifier that amplifies the detected value from the sensor.

The comparator 13 corresponds to the data determination circuit 4 in FIG. The output of 13 is supplied to a control circuit 14 and also to a timer 15.

The control circuit 14 is a circuit that controls the display operation of the display section 6a. For example, when a person to be measured finishes measuring his or her weight and steps off the scale, the load on the scale becomes large and then becomes zero. Therefore, if a child or the like jumps down, the change will be even worse, so the controller is in charge of controlling the display to immediately return it to zero in such a case.

The timer 15 is set to the time required for the person to be measured to settle down in a stable position on the weight scale and the time for the sensor to stabilize the detected value, for example, about 3 to 5 seconds. The operation is started and a high level signal is given to the hold circuit determination circuit 18 and the audio circuit 19 for a set period of time as shown by the symbol S. The audio circuit 19 receives a signal from the timer 15 and is activated to generate a melody and activate the speaker 20.

On the other hand, the output of the comparator 13 is also given to the hold circuit determination circuit 18 via the delay circuit 16. In this hold circuit determination circuit 18, the comparator 13 is ON.
, turns on the hold circuit 17 when the timer 15 is off.
While the logic is established, the hold circuit 17 causes the display 6a to display the detected weight value given from the A/D converter 3 of FIG. 1.

As described above, a thin and lightweight simple weight scale can be constructed using pressure-sensitive conductive rubber as a sensor.

The scale of this example can be made lightweight and thin, with a thickness of about 1 cm and a weight of several hundred grams, so even children can handle it freely, and it can be stored by leaning it on a bookshelf or hanging it on a wall. It is extremely convenient, and since there are no moving parts, it can be used even on tatami mats.

As mentioned above, pressure-sensitive conductive rubber can be used as the measuring element of weight scales by using LEDs (or LCDs) for signs, using batteries or solar batteries as the power source, and using ICs for each circuit to make them thinner, lighter, and more compact. Various advantages can be obtained by using it as a

In other words, although a numerical value is displayed digitally, if it is determined that a load has been applied to the sensor and the sensor is held after a predetermined time, the holding circuit eliminates the need to read the numerical value in an unstable state. , reading can be done easily and accurately.

In addition, while the conventional scale simply measures the weight, the digital scale with the above structure has a function to memorize the measured weight, and since the sensor itself has electrical characteristics, it is easy to memorize the numerical value. This can be achieved at a low price.

Furthermore, this weight scale makes an electronic melody while measuring the weight, and also allows comparison with the average weight using the memory. The melody is played until the measurement is stabilized, which is very effective, and the ability to compare with the average weight, etc. allows for health management.

In this way, it is possible to easily provide additional functions that have not been seen in the past.

Furthermore, in addition to functions such as memory and melody, designs combined with popular characters such as TV and Mango,
By using a display means and a theme melody, the product value can be further increased.

〔Effect of the invention〕

This invention uses a pressure-sensitive conductive rubber as a sensor, extracts the load at the time of weight measurement from the pressure-sensitive conductive rubber as a change in resistance value, adds this to the measurement circuit, and displays it on the display section. It can be easily made lighter and thinner, it does not have to be placed anywhere, it is convenient because it is thin and lightweight, and it can be measured even on tatami or carpet.
It is particularly suitable for use as a simple weight scale for general household use.

Furthermore, since the weight scale of the present invention converts body weight into an electrical quantity, it is possible to eliminate misreading by using an electronic circuit and a digital display, so even children can handle it.
It can be useful for home health management by memorizing the previous measurement value and general average weight, and the electronic sound and display make it easy to take measurements, making it easy to use even for people who are not used to handling it. It has the advantage that various functions such as easy and accurate measurement can be added.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2(A) is a cross-sectional view of the weight scale of the embodiment, and FIG. 2(B) is a partially cutaway view of the embodiment. Fig. 3 is a plan view of the weight scale, Fig. 3 is a plan view when four sensors are arranged on the base, Fig. 4
FIG. 1 is a block diagram showing a modification of the data determination circuit shown in FIG. l...pressure-sensitive conductive rubber sensor section, 2...analog signal amplification circuit section, 3...A/D converter circuit section, 4...
- Data judgment circuit, 5... Memory circuit, 6... Indicator, 7... Board, 8... Rubber plate, 9... Sensor part, 10... Load holder, 11...・Void.

Claims (1)

[Claims] A pressure-sensitive conductive rubber sensor section that extracts the load of the scale as a change in the resistance value of the pressure-sensitive conductive rubber, a measurement circuit that generates an electric signal corresponding to the change in resistance value, and an indicator section that indicates the weight using the electric signal. A weight scale comprising: