JPS643089Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an object detection device that detects the amount of powder, etc. using a piezoelectric vibrator, and particularly relates to an improvement of a support cylinder portion that supports the piezoelectric vibrator.

FIG. 1 shows a conventional object detection device of this type.
In this figure, a box-shaped case 3 is constituted by a base 1 and a lid 2, and a support tube 4 is integrally formed with the lid 2. A piezoelectric vibrator 5 is bonded to the distal end surface of the support cylinder 4 at its peripheral edge. Inside the case 3, an oscillation circuit that utilizes the resonance characteristics of the piezoelectric vibrator 5 is mounted on a substrate 6.

The piezoelectric vibrator 5 is made of copper, as shown in FIGS.
A piezoelectric ceramic 11 is attached onto a diaphragm 10 made of a thin plate of non-magnetic metal such as aluminum, and electrodes 12A and 12b are formed on this piezoelectric ceramic 11. Here, the diaphragm 10 has each electrode 12
Lead wires 13A to 13C are connected to the diaphragm 10 and each electrode 12A, 12B for electrical connection. The oscillation circuit is normally a feedback oscillation circuit using the electrode 12A as the main electrode and the electrode 12B as the feedback electrode, and when the object to be detected comes into contact with the diaphragm 10, the Q of the piezoelectric vibrator 5 decreases and stops oscillation. It is something to do.

1 is placed on the bottom or lower side of a container that contains an object to be detected, such as powder, in actual use, so that the diaphragm 10 side of the piezoelectric vibrator 5 comes into contact with the object to be detected. When the amount of the object to be detected exceeds a certain value and the Q of the piezoelectric vibrator 5 drops to a certain extent, the oscillation circuit stops oscillating, thereby detecting the amount of the object to be detected.

By the way, in the case of FIG. 1, the support tube 4 is attached to the case 3.
Generally, the piezoelectric vibrator 5 is made of the same material, that is, resin, but with such a structure, the vibrations of the piezoelectric vibrator 5 propagate to the case 3 through the support tube 4,
Case 3 occurs due to increased vibration energy and loss leakage.
The actual detection operation was extremely unstable due to standing waves riding on the structure containing the sensor. Therefore, in the case of powder weight detection, for example, the detection sensitivity varies in the range of 200 to 600 g. In addition, the selection of good and defective products can only be carried out at the final stage (the stage when the case 3 is attached to a storage container, etc.), which not only results in a low yield but also inconveniently requires time and effort for inspection.

In view of the above points, the present invention stabilizes the object detection operation by configuring at least a part of the support cylinder that supports the piezoelectric vibrator with a ring-shaped block made of non-magnetic metal, and reduces the variation in detection sensitivity. The purpose is to provide a detection device.

Embodiments of the object detection device according to the present invention will be described below with reference to the drawings.

In FIGS. 3 and 4, the base body 1 and the lid body 2A
A box-shaped case 3A is constructed by the lid body 2.
At A, a ring-shaped protrusion 20 forming the base of a support tube supporting the piezoelectric vibrator 5 is integrally formed of resin or the like. Further, the piezoelectric vibrator side portion of the support tube is composed of a ring-shaped block 21 made of non-magnetic metal such as steel or aluminum.
is bonded to the ring-shaped protrusion 20 with a resin 22 having a large vibration loss, such as urethane rubber. Further, the peripheral edge of the piezoelectric vibrator 5 is attached to the tip surface of the ring-shaped block 21 with an elastic adhesive layer 23 made of silicone resin or the like.
It is installed in Note that an oscillation circuit that utilizes the resonance characteristic (Q change) of the piezoelectric vibrator 5 is mounted on the substrate 6 housed in the case 3A.

According to the above embodiment, the ring-shaped block 21 made of non-magnetic metal constitutes a part of the support cylinder, and this ring-shaped block 21 effectively prevents the vibration of the piezoelectric vibrator 5 from being transmitted to the case 3A side. can be prevented.
In addition, to further ensure this effect,
A ring-shaped block 21 is connected to the case-side ring-shaped protrusion 20 with a resin having a large vibration loss. Therefore, the detection operation can be performed stably without being affected by the case mounting state, position, etc., and variations in detection sensitivity can be reduced. For example, in the case of powder weight detection, the conventional variation in the range of 200 to 600 g falls within the range of 320 to 400 g, which is about 1/2 or less. Therefore, the product yield can be significantly improved,
Furthermore, it is possible to sort out non-defective products and defective products at a stage before the final stage.

As explained above, according to the present invention, it is possible to obtain an object detection device that can perform object detection operations stably and with little variation. , cocoa, etc.) can be suitably used in detectors, etc. Furthermore, as a result of improved accuracy, it can also be used as a pressure detection sensor.

[Brief explanation of drawings]

Fig. 1 shows a conventional object detection device, and is a perspective view with a piezoelectric vibrator and a support tube sectioned in section, Fig. 2A is a front view of the piezoelectric vibrator, Fig. 2B is a bottom view, and Fig. 2A is a front view of the piezoelectric vibrator. FIG. 3 is a perspective view showing an embodiment of the object detection device according to the present invention, with the piezoelectric vibrator and the support tube section taken in section, and FIG. 4 is an enlarged sectional view of the main part of the embodiment. 1...base body, 2,2A...lid body, 3,3A...
Case, 4... Support cylinder, 5... Piezoelectric vibrator, 6...
...Substrate, 10...Diaphragm, 11...Piezoelectric ceramic, 20...Ring-shaped protrusion, 21...Ring-shaped block.

Claims (1)

[Scope of utility model registration request] In an object detection device that supports a piezoelectric vibrator with a support tube protruding from a case, and utilizes the fact that the resonance state of the piezoelectric vibrator changes depending on whether or not an object to be detected contacts the piezoelectric vibrator, At least a part of the piezoelectric vibrator side of the support tube is constituted by a ring-shaped block made of non-magnetic metal, the piezoelectric vibrator is adhered to the ring-shaped block with an elastic adhesive, and the ring-shaped block is attached to the case side. An object detection device characterized by being connected using resin with high vibration loss.