JPS6120823A - Electronic balance - Google Patents

Abstract

PURPOSE:To measure the absolute value of mass by supporting the movable part of the balance on a housing through two diaphragm, and constituting a dynamic type electro-acoustic transducer at one terminal of the movable part and an electrostatic type electro-acoustic transducer at the other terminal. CONSTITUTION:The movable part A is supported on the housing 6 through two diaphragms 7. The circular plane D of a movable part body 3 and the circular plane F of a fixed electrode 11 constitute a capacitor and the DC voltage of a battery B is applied to constitute the electrostatic type electr-optic transducer H. When a mechanical or electric shock is applied to the movable part A or electric circuit, the electric output of the transducer H is amplified 15. The circuit oscillates when the phase difference between the input and output of the amplifier 15 is selected properly. The mass (m) of a body 1 to be measured is calculated from m=M(f0<2>/fm<2>-1), where f0 is the resonance frequency of this oscillation system, fm is the oscillation frequency when the body 1 to be meas- ured is placed on a measuring pan 2, and M is the substantial mass of the movable part A. For the purpose, the mass M and frequency f0 are measured previously, and then the mass (m) is calculated by measuring the frequency fm.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic scale. The feature is that the movable part of the scale is supported by two diaphragms in the housing, a movable coil is wound around one end of the movable part to create an electrodynamic electroacoustic transducer, and a flat electrode is provided at the other end to create a static electrostatic transducer. configuring an electrostatic type electroacoustic transducer, and amplifying the electrical output of the electrostatic type electroacoustic transducer and supplying it to the movable wire of the electrodynamic type electroacoustic transducer, that is, configuring an oscillation circuit. That's true.

Conventional scales,! With the exception of balances, all instruments measure the earth's gravitational pull on an object and calculate its mass by dividing it by the acceleration of gravity at the measurement location. Therefore, if the measurement location changes, the measured value will be different.

According to the Science Chronology compiled by the Tokyo Astronomical Observatory, the standard gravity at the equator is 978.031845586a1, and that at the poles is 98i21772792gal, a difference of 0.53%. Therefore, it must be kept in mind that even if a measurement is made using a scale with an accuracy of 0.1%, there will be a similar amount of error.

Also, the buoyant force of the air acting on the object to be measured must be taken into consideration. Now the density of air 'fK 0, 0012 g//
When measuring the mass of plastic with a specific gravity of 1.2 cm5, it is subject to a buoyancy force of 0.1. Also, when measuring with a balance, if the specific gravity of the object to be measured and the specific gravity of the weight are different, correction must be made based on the buoyancy of air.

The present invention eliminates the above drawbacks and will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view for explaining the operating principle of the present invention. In the figure, / is the object to be measured, 2 is the saucer, 3 is the main body of the movable part, and g is the bobbin. is a movable ring,
2.3.4 and Yu can move as one. 2, 3.
The part in which 4 and 4 are integrated is called the movable part A. B is a housing, and 7 is a diaphragm.As shown in the figure, the movable part A is supported by the housing. t is a permanent magnet, N, E
t is the magnetic pole. The holes and /θ are fixed to the enclosure with a ball and yoke made of soft magnetic material. ! .

? , 9 and /θ constitute an electrodynamic electroacoustic transducer C. // is a fixed electrode, /ko is a fixed electrode that is fixed with insulating glass. The facing surfaces of the movable part main body 3 and the fixed electrode // are both circular planes and F, and the thickness of the gap length G&i spacer /3 can be adjusted to a desired value.

/4t is the platform.

Figure 2 is an example of a circuit diagram showing the electrical connections of the electronic scale of the present invention, where B is a battery, R is a high resistance, /! is an amplifier, and the other symbols are the same as in FIG.

In FIG. 1, the movable part A is fully supported by the two diaphragms 2 on the housing B as shown in the figure, so it has a degree of freedom of movement in the vertical direction in the drawing, but no lateral vibration occurs. If the stiffness of the diaphragm 7 seen from the movable part A is 6, and the effective mass of the movable part A is M, then the resonance frequency fo of this vibration system is as shown in equation (1), where 71:o is a pi.

When the electronic scale shown in FIG. 1 is connected as shown in FIG. Electroacoustic transducer, so-called condenser microphone Hi
Configure.

If some form of mechanical or electrical shock is applied to the movable part A or the electrical circuit shown in FIG. 2, the electrical output of the condenser microphone H will be changed to the amplifier/! The width is increased by Amplifier/! If the input/output phase difference is appropriately selected, the circuit shown in FIG. 2 will oscillate, and the oscillation frequency will be fo as shown in equation (1).

Here, assuming that the mass of the object to be measured is m, if the object is placed on the receptacle, the oscillation frequency changes to fm as shown in equation (2).

From equations (1) and (2) Obtain the result of equation (3).

If M and foe are measured in advance and used as known quantities, then by measuring the oscillation frequency fm, the mass m of the object to be measured can be calculated as (3
) can be calculated from the formula.

As explained above in detail with respect to the drawings, the electronic scale of the present invention is not affected by the earth's gravitational force and the buoyant force of the air, so the relationships in equations (1), (2), and (5) are not affected by the buoyant force of the air. The mass of the object to be measured is an absolute value in vacuum.

Moreover, what is weighed by the electronic scale of the present invention is the oscillation frequency fm of the oscillation circuit. The purpose of this is to provide a highly accurate electronic scale that is not only simple but also less affected by various noises, which makes it easier to configure the calculator for obtaining various data in digital quantities. I can do it.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view for explaining the operating principle of the electronic scale of the present invention, and FIG. 2 is a circuit diagram showing one embodiment of the electrical connection of the electronic scale of the present invention. D...Object to be measured, λ...Saucer, 3...
・Movable body, bobbin,! ...Movable wire ring, g...Casing, 2...Diaphragm,?・Old・
・Permanent Δ magnet, 2 and /θ...pole and yoke,
//... Fixed electrode, /2... Insulated glass, /
! ......Amplifier, A...Movable part, B...
・・Battery, C・・Electrodynamic electroacoustic transducer, H・・
...An electrostatic electroacoustic transducer. Patent applicant: International Technology Development Co., Ltd. DFG
/4t

Claims (1)

[Claims] The movable part of the scale is supported by the housing with two diaphragms, and a movable coil is wound around one end of the movable part to create an electrodynamic electroacoustic transducer, and a flat electrode is provided at the other end to create an electrostatic electroacoustic transducer. The invention is characterized in that an oscillation circuit is constructed by amplifying the electrical output of the electrostatic electroacoustic transducer and supplying it to the movable wire of the electrodynamic electroacoustic transducer. An electronic scale that measures the absolute value of mass.