JPS6123773Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic weight measuring device, and is an object of the present invention to provide a device with a relatively simple configuration that can easily perform digital signal processing.

In digital signal processing of conventional electronic weight measuring devices, weight-related information is detected as an analog signal, and this analog signal is converted to an A/D.
Conversion into a digital signal is performed using a converter. In this case, in order to improve the resolution, it is inevitable that the configuration of the A/D converter becomes complicated, and the cost also increases. To solve these drawbacks, for example, devices using vibrating strings have been put into practical use. This detects the natural frequency that changes depending on the tensile force applied to the vibrating string, and since a frequency signal can be obtained directly, signal processing becomes easy. However, such a vibrating string requires an initial force, which must be applied as a pulling force. In addition, the amount of displacement due to force increases, and vibration detection methods are limited, etc.
This will involve various restrictions.

The present invention solves these drawbacks and will be described in detail below with reference to the drawings.

FIG. 1 is a configuration explanatory diagram showing one embodiment of the present invention, in which numeral 1 denotes a saucer used as a force generation mechanism that generates a force corresponding to the weight of the object W to be measured; It is a vibrating body whose natural frequency changes. 3 is a parallel link used as a force transmission mechanism for transmitting the output of the saucer 1 to the vibrating body 2, and acts as a roberval mechanism. These saucer 1, vibrator 2 and parallel link 3 are connected to the object to be measured W.
It constitutes a weight measuring mechanism that converts the weight of the vibrating body 2 into the natural frequency of the vibrating body 2 and sends it out. 4 is the base,
SP is a spring and ST is a stopper, which act as a protection mechanism to protect the weight measurement mechanism from excessive load.

A mounting hole 11 is formed on the bottom surface of the saucer 1 so as to fit into one end a of the vertical lever 31 of the parallel link 3.
is formed. Further, stoppers ST ₁ and ST ₂ are arranged on the base 4 so as to face the bottom surface of the saucer 1.

One end of the vibrator 2 is fixed to the base 4, and the other end is rotatably connected to one end b of the parallel lever 32 of the parallel link 3. FIG. 2 is a configuration explanatory diagram showing an example of such a vibrating body 2, and is an example in which a single prismatic body is cut into a predetermined shape so as to be symmetrical with respect to a central axis orthogonal to each other. It shows. In FIG. 2, two vibrating pieces VA and VB which are symmetrical and parallel to the central axis are formed by cut holes HC provided along the long axis direction. The remainder of the through hole HC forms coupling pieces CA and CB that couple the ends of the vibrating pieces VA and VB, respectively. In the extension direction of these connecting pieces CA and CB,
Plate-shaped flexures FA ₁ , each at right angles to each other
~FA ₃ , FA ₁ ~ _{FA 3} and mounting pieces PA, PB are formed. These flexures and mounting pieces are
This constitutes the mounting parts SA and SB. EX is an exciter, and DT is a detector, which together with the vibrating body 2 form an oscillation circuit. These exciters EX
As the detector DT, for example, a piezoelectric element is used. In such a vibrating body 2, when an axial force S is applied in the long axis direction, the resonant frequency of the vibrating body 2 changes, and the oscillation frequency of the oscillation circuit also changes. By making this oscillation mode a symmetrical mode that vibrates symmetrically with respect to the central axis in the long axis direction,
The reaction force and moment generated at the connection between the vibrating pieces VA, VB and the coupling pieces CA, CB are equal in magnitude in opposite directions and cancel each other out, so that the vibration energy does not leak to the outside. , a vibrating body 2 with excellent quality can be obtained. In addition, the mounting part
The SA and SB flexures FA ₁ to _{FA 3} and FB ₁ to _{FB 3} can remove stress from the bent portions caused by attachment of the ends, and provide vibrational isolation between the vibrating body 2 and the outside.

Referring again to FIG. 1, one ends c and d of the parallel levers 32 and 33 of the parallel link 3 are rotatably attached to the base 4, respectively. One end e of the parallel lever 33 is rotatably connected to an intermediate portion of the vertical lever 31, and an intermediate portion f of the parallel lever 32 is rotatably connected to the other end of the vertical lever 31. A flange 34 for locking a spring SP is formed at the end a of the vertical lever 31 so as to face the end surface of the mounting hole 11 of the saucer 1, and the saucer 1 is vertically attached via the spring SP. It is coupled to one end a of the lever 31.

The operation of such a configuration will be explained.

By placing the object W on the saucer 1,
A force is generated in the saucer 1 that pushes down the parallel link 3. This force is applied to the vibrating body 2 via the parallel link 3. As a result, the natural frequency of the vibrating body 2 changes depending on the applied force. Therefore, by measuring the change in the natural frequency of the vibrating body 2, the weight of the object W to be measured can be determined. Note that the object to be measured W placed on the saucer 1
Even if the weight of the vibrating body 2 is excessive, the vertical displacement of the tray 1 is regulated by the stoppers ST ₁ and ST ₂ arranged opposite to each other on the bottom of the tray 1.
Excessive force is not applied to the Furthermore, since the saucer 1 and the parallel link 3 are coupled via the spring SP, sudden changes in force can be prevented from being applied to the vibrating body 2. Furthermore, since the parallel link 3 which acts as a roberval mechanism is used as the force transmission mechanism, the correct force is always applied to the vibrating body 2 no matter where the object W is placed on the tray.

FIG. 3 shows a modification of FIG. 1, in which the saucer 1 and the vertical lever 31 of the parallel link 3 are integrated, and the stopper ST ₃ is arranged to face the lower end of the vertical lever 31. One end of the vibrating body 2 is fixed to the base 4 via a spring SP. With this configuration as well, it is possible to realize a device that performs the same operation as that shown in FIG. 1 described above.

FIG. 4 is a block diagram showing an example of the circuit configuration for signal processing in FIG. Input circuit for information such as unit price,
8 is the output signal of the period measuring circuit 6 and the input circuit 7
9 is a display circuit that digitally displays the results of the arithmetic circuit 8. As is clear from FIG. 4, digital signal processing can be easily performed with a relatively simple configuration without using a conventional A/D converter.

In the above embodiments, an example is described in which a saucer is used as the force generating mechanism, but the object to be measured may be suspended.

Furthermore, it is also possible to improve temperature characteristics, sensitivity, S/N ratio, etc. by arranging vibrating bodies with similar characteristics so that force is applied differentially.

Further, by using a platform scale mechanism as the force transmission mechanism, the same effect as the Roberval mechanism can be obtained.

Further, instead of the spring shown in FIG. 1, a magnetic support mechanism such as a magnetic bearing may be used.

Furthermore, a magnetic support mechanism may be used in the support section of the vibrating body. In this case, using the repulsion of a magnet,
You can use magnetic attraction. When using magnet attraction, by interposing rubber, plastic, etc. between the vibrating body and the base, vibrations of the vibrating body can be prevented from leaking to the outside. Further, by using such a magnetic support mechanism, when an overload is applied to the vibrating body, the magnetic support is removed, and the vibrating body can be reliably protected.

As explained above, according to the present invention, it is possible to realize a weight measuring device that can easily perform digital signal processing with a relatively simple configuration, and its practical effects are great.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention;
Fig. 2 is a configuration explanatory diagram showing an example of a vibrating body used in the present invention, Fig. 3 is a configuration explanatory diagram showing a modification of Fig. 1, and Fig. 4 is a signal processing diagram in the device shown in Fig. 1 or Fig. 3. FIG. 5 is a block diagram showing an example of the circuit structure for the present invention. 1... Force generation mechanism (saucer), 2... Vibrating body, 3
...Force transmission mechanism (parallel link), 4...Base,
5...Oscillation circuit, 6...Period measurement circuit, 7...Input circuit, 8...Arithmetic circuit, 9...Display circuit.

Claims (1)

[Scope of utility model registration request] Weight measurement consists of a force generation mechanism that generates a force corresponding to the weight of the object to be measured, a vibrating body whose natural frequency changes according to the applied force, and a force transmission mechanism that transmits the output of the force generation mechanism to the vibrating body. In a weight measuring device equipped with a mechanism and a protection device for protecting the weight measuring mechanism from excessive load, one block is provided as the vibrating body symmetrically in parallel to the central axis, and the axial force to be converted is substantially A long-axis vibrating part that is applied in the axial direction, a connecting part that connects one end of each of the vibrating parts, and a supporting part having a plate-like flexure that has one end connected to the connecting part are used. A weight measuring device characterized by: