JPH025376Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention is a vibrating electronic scale, specifically a vibrating electronic scale that detects a resonance frequency that changes in response to the weight of an applied load and generates a weight signal. Regarding.

(Prior Art) The structure of a conventional vibrating electronic scale will be explained with reference to FIGS. 7 and 8.

In the figure, 24 is a vibrator, and this vibrator 24 is 2
Connect the tips of each piece to form a single piece,
It is provided with piezoelectric elements 34 and 35 for excitation and detection, and the vibration frequency increases or decreases according to changes in load.

The weight detection section will be explained. A lever 26 is integrally formed on the upper part of the mounting plate 25 via a fulcrum 27. The upper end of the vibrator 24 is integrally formed with one end of the lever 26, and the lower end is integrally formed with the lower part of the mounting plate 25. The other end of the lever 26 is used as a force point to apply the weight of the object to be weighed. The mounting plate 25 of the vibrator 24 is fixed to the mounting member 22, and the mounting member 22 is attached to the base plate 36.
It is attached to a support member 21 that is attached in an upright manner above.

The Roberval mechanism will be explained. The support member 2
There are four leaf springs 3 at both ends of 1 (upper and lower in Fig. 7).
The beam plates 33 each having a substantially inverted C shape as shown in FIG.

A plate support member 29 is provided at the center of each of the beam plates 33 via four leaf springs 32 in two stages vertically, and the lower part of the plate support member 29 is connected to the point of force of the lever 26 via a connecting link 28. is connected to.

In the conventional structure, when a load is applied to the plate support member 29, the load is applied to the force point of the lever 26 via the connecting link 28, and the force is applied to the vibrator 24 via the fulcrum 27.
A tensile force is applied to the oscillator 24, and the vibration frequency of the vibrator 24 changes.

The conventional vibrating electronic scale has the following drawbacks.

Support member 21, two beam plates 33, plate support member 29
The structure is complicated because the Roberval mechanism is configured separately from the weight detection section using eight leaf springs 32.
Moreover, the number of parts is large, and assembly workability is poor, and assembly errors are likely to occur.

The vibrator 24 is connected to the lever 26, the mounting plate 25 and the fulcrum 2.
Since it is formed integrally with 7, processing is difficult and productivity is poor. Additionally, due to its structure, it has weak strength and must be handled with care.

(Purpose of the invention) The present invention was devised in view of the above-mentioned conventional circumstances, and its purpose is to provide a vibrating electronic balance with an extremely simple structure, a small number of parts, good assembly workability, and a very high strength. Our goal is to provide the following.

(Structure of the invention) The vibrating electronic scale of the present invention is configured such that one side of the rectangular frame-shaped strain body constituting the Roberval mechanism is configured as the emphasis side and the other side as the fulcrum side. The present invention is characterized in that an excitation means for vibrating the strain body at a natural frequency and a vibration detection means for detecting a change in the natural frequency due to a load applied to the strain body are provided at or near the body.

(Function) With the above configuration, the vibrating electronic scale of the present invention vibrates the strain body using the excitation means, detects the natural frequency of the strain body corresponding to the weight of the load using the vibration detection means, and detects the natural frequency of the strain body corresponding to the weight of the load. The detected value is used as a weight signal.

(Example) Hereinafter, an example of the present invention will be described using the drawings. 1 and 2 show its structure, and FIG. 3 shows its electrical configuration.

Reference numeral 20 in FIG. 1 is a base plate, and a support 2 is provided in an upright manner on the base plate 20, and one end of the strain-generating body 1 is attached to the upper part of this support 2.

The strain body 1 has a square frame shape that constitutes a roberbal mechanism consisting of upper and lower horizontal beam parts 1c, 1d and left and right connecting parts 1b, 1a, with one connecting part 1a on the fulcrum side and the other connecting part on the fulcrum side. Use 1b as the focus side. That is, the connecting portion 1a on the fulcrum side is attached and fixed to the support column 2 using a fixing screw or the like (not shown).

A plate receiving plate 3 is attached and fixed to the connection portion 1b on the above-mentioned important side by means of attachment screws 3a. This plate receiving plate 3
A weighing pan 4 is provided.

As shown in FIG. 2, a piezoelectric element 7 is provided as an excitation means at the lower part of the connection portion 1b on the important side of the strain body 1.
At the same time, a permanent magnet 5 is embedded in the longitudinal side surface so that a part of the permanent magnet 5 protrudes from the surface. A magnetic head 6 is disposed close to the permanent magnet 5 as a frequency detecting means. This magnetic head 6 is attached to a mounting post 8 fixed on a base plate 20.

In the above configuration, when an alternating current voltage of a predetermined frequency is applied to the piezoelectric element 7 to cause it to vibrate, the strain body 1 vibrates. When the strain body 1 vibrates, the permanent magnet 5 vibrates together, and the magnetic field around the permanent magnet changes in synchronization with the frequency of the strain body 1. As a result, a detection voltage e is induced in the magnetic head 6 that changes in synchronization with a change in the magnetic field, that is, a change in the frequency of the strain body 1.

This induced detection voltage e is supplied to the amplifier circuit 11 of the weight detection section 10 as shown in FIG. 3, and a part of it is fed back to the excitation circuit of the piezoelectric element 7 (not shown). As a result, the excitation circuit controls the frequency applied to the piezoelectric element 7 so that the strain body 1 continues to vibrate at its natural frequency. Description of the excitation circuit will be omitted here since it is not directly related to the present invention.

Next, an electrical configuration for converting the frequency change occurring in the magnetic head 6 into weight will be explained with reference to FIG.

10 in the figure is a weight detection section, and this weight detection section 10 includes a permanent magnet 5, a magnetic head 6, and an amplifier circuit 1.
1. Consists of a waveform shaping circuit 12 and a counting circuit 13.

The amplifier circuit 11 amplifies the signal voltage e induced in the magnetic head 6 and inputs it to the waveform shaping circuit 12. The waveform shaping circuit 12 converts the input AC voltage into a pulse signal SP and inputs it to the counting circuit 13. The counting circuit 13 counts the input pulse signal SP for a certain period of time and outputs this counting result SW.
is input to the CPU 15.

The CPU 15 is connected not only to the counting circuit 13 but also to an operating section 14, a ROM 16, a RAM 17, a printing section 18, and a display section 19.

The ROM 16 is a memory that stores control programs such as a conversion program for counting results SW and weight, and a printing control program for labels and receipts. The RAM 17 is a memory used by the CPU 15 while executing a control program and for storing preset data such as product name and unit price. The operation unit 14 includes a numeric keypad, function keys, etc., and sends various commands and data to the CPU 15.
This is what you have to input. The printing section 18 is the operation section 1
It is driven by the print command No. 4 and prints and issues labels, receipts, etc. according to the print control program in the ROM 16. The display section 19 is an LED,
It consists of an LCD, etc., and displays the product name, unit price, weight, price, etc.

The count result SW input from the counting circuit 13 to the CPU 15 is converted into a weight value by executing the conversion program in the ROM 16.

This weight value is displayed on the display section 19 along with the price, product name, etc. calculated from this weight value and unit price, and is also printed on a receipt, label, etc. by the printing section 18 based on printing support from the operation section 14. be done.

In this embodiment, since the permanent magnet 5 for detecting vibration and the magnetic head 6 are not in contact with each other, it is extremely easy to perform moisture-proofing treatment on the circuit portion of the weight detection section 10.

In the above embodiment, the natural frequency is detected by counting the pulse signals supplied to the counting circuit 13 for a certain period of time, but the present invention is not limited to this. For example, when the frequency of the signal voltage e is relatively low, it may be possible to shorten the measurement time by detecting the length of the wavelength.

Furthermore, if the vibration of the strain body 1 is transmitted to the weighing pan 4 or the base plate 20, it is not preferable in terms of efficiency.
It is desirable to interpose vibration transmission prevention means, such as a patch made of an elastic body, between the connecting portion 1a of the strain body 1 and the support column 2, and between the connecting portion 1b and the plate mounting plate 3, respectively.

Incidentally, if the mass of the strut 2 is sufficiently larger than that of the strain body 1 and the natural frequencies of the strain body 1 and the strut 2 are significantly different, transmission of vibration to the strut 2 is prevented.

Furthermore, the mounting column 8 is made to have high strength so that it will not vibrate together.

In addition, numeral 9 in the figure is a stopper for preventing an excessive load, and is composed of a stud bolt.

Next, modified examples of the excitation means and the vibration detection means will be described, and those having the same configuration will be denoted by the same reference numerals and the description thereof will be omitted.

The second embodiment will be explained with reference to FIG. 4. In place of the permanent magnet 5 and magnetic head 6, which are the vibration detection means of the first embodiment, a piezoelectric element 6' is pasted on the opposite side of the piezoelectric element 7 for excitation. The other configurations are the same as those of the first embodiment. By doing so, the structure of the vibration detection means can be simplified.

A third embodiment will be explained with reference to FIG.

An iron piece 5' is provided on the side surface of the connecting portion 1b on the important side of the strain-generating body 1, and an electromagnet 7' is provided below the iron piece 5'. The strain body 1 is made to vibrate. Furthermore, a piezoelectric element 6' is attached to the upper surface of the connecting portion 1a on the fulcrum side to detect vibrations of the strain body 1.

A fourth embodiment will be explained with reference to FIG.

This is an example of an excitation means. Piezoelectric elements 7'' are attached to each of the four strain-generating parts 1e of the strain-generating body 1, and even a large strain-generating body can be reliably vibrated by exciting each piezoelectric element 7''. It was designed so that still,
The vibration detection means is optional.

(Effects) As described above, the present invention configures one side of the rectangular frame-shaped strain body constituting the Roberval mechanism as the emphasis side and the other as the fulcrum side, and also configures the strain body or its vicinity. The vibrating electronic scale is characterized by having an excitation means for causing the strain body to vibrate at its natural frequency, and a vibration detection means for detecting a change in the natural frequency due to a load applied to the strain body. There is a similar effect.

Compared to load cell-type electronic scales that use strain gauges, the power consumption is about 1/100, so the power cord can be eliminated and a compact structure can be achieved using dry batteries or solar batteries. Moisture-proofing is easier with the vibration type than with the strain gauge type. Similarly, the number of parts is small and the structure is simple, and an A/D converter is not required, so the circuit can be simplified. Therefore accuracy 1/3000
It can be manufactured at low cost as a grade display scale.

Also, compared to the vibrating electronic scale mentioned in the conventional technology,
Since the Roberval mechanism itself is used as a vibrator, the structure is simpler than the conventional structure consisting of a vibrator and Roberval mechanism, and since there are fewer components, cumulative installation errors are reduced and accuracy is improved. Furthermore, since a weak vibrator as shown in FIGS. 7 and 8 is not used, the strength is very high.

By doing so, we will reach our intended purpose.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view showing the structure of a vibrating electronic scale according to the first embodiment of the present invention, FIG. The figure is a plan sectional view of the main part showing the main part of the second embodiment, Fig. 5 is a front view of the third embodiment, Fig. 6 is a front view of the fourth embodiment, and Fig. 7 is a plane view of the conventional example. 8 is a sectional view taken along the line -- in FIG. 7. In the figure, 1...flexible body, 1a...fulcrum side, 1b...
...Important side, 5...Permanent magnet, 6...Magnetic head,
6'...Piezoelectric element, 7...Piezoelectric element, 7'...Electromagnet, 7''...Piezoelectric element.

Claims (1)

[Scope of utility model registration request] One side of the rectangular frame-shaped strain body constituting the Roberval mechanism is configured as the emphasis side and the other as the fulcrum side, and the strain body or its vicinity is excited to vibrate the strain body at its natural frequency. A vibrating electronic scale, characterized in that it is provided with a vibration detecting means for detecting a change in the natural frequency due to a load applied to the means and the strain body.