JPH1164092A - Vibration detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the lifetime by connecting a fixed part and a movable part electrically through a flexible printed wiring board FPWB, thereby enhancing the bending strength of the electrical connection means. SOLUTION: An FPWB 21 has one end soldered to a printed circuit board 16 at a movable part 31 for mounting a vibration detecting element (piezoelectric element) and an amplifier circuit for the output signal therefrom and riveted to a base 5, and the other end soldered to a connector 10 fixed to the end of a cable 15. The FPWB 21 is produced by forming a wiring pattern of copper foil on a polymide resin sheet and covering the wiring pattern with an insulation layer, wherein a slightly right-of-center part 21b (toward the connector) is made thick, along with the vicinity 21a of the fixing part to the connector 10 where the movable part 31 is pushed in at the time of detecting the vibration and bending is concentrated. Since the radius of curvature does not becomes excessively small at both parts 21a, 21b, an open circuit of a lead pattern is suppressed at those parts and the FPWB 21 itself is protected against rupturing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration detecting device for converting a vibration into an electric signal by contacting a vibrating object and detecting a vibration state of the vibrating object.

[0002]

2. Description of the Related Art Conventionally, as a vibration detecting device of this type,
As shown in Japanese Utility Model Publication No. 5-24025, the whole vibration detecting device is directly screwed and fixed to a vibrating object,
As shown in Japanese Patent Application Laid-Open No. 5-126622, there is known an apparatus in which a vibration detection device is held by hand and pressed against a vibrating object for use. Some of the devices which are used by pressing a vibration detecting device against a vibrating object include Japanese Utility Model Laid-Open No. 4-7592.
As disclosed in Japanese Patent Application Publication No. 3 (1999) -1995, a part to be pressed is a movable part urged by a spring, and a movable part provided with a piezoelectric element is known.

[0003] These vibration detecting devices are assumed to be used for diagnosis and maintenance of mechanical equipment, judging from the description in the above-mentioned publication and the usage of the vibration detecting devices on the market up to the present. . In other words, those that are directly screwed to a vibrating object are those that are permanently installed in machinery and equipment to monitor abnormal vibrations, and those that are pressed are those that are carried by maintenance personnel of machinery and equipment and diagnosed. It is for inspecting equipment and going around.

The inventors of the present application believe that the vibration detecting device has a new use of inspecting a mass-produced product having a built-in vibration source, and a vibration detecting unit of the vibration detecting device particularly suitable for such a use. (Vibration sensor head) and an analysis method of the detected vibration waveform signal have been developed. A vibration detector with a movable part biased by a spring is suitable for the inspection of mass-produced products of this type, but as a result of the investigation, there is no known vibration detector that specifically assumes such a use. There was found.

[0005]

With respect to the characteristics required of the vibration detecting device, it is assumed that the vibration detecting device according to the present invention is used for diagnosis and maintenance of mechanical equipment assumed by the conventional pressing type vibration detecting device. There is a remarkable difference in the durability required for the movable part of the vibration detecting device between the mass production product inspection application and the mass production product inspection application, and a much higher level of durability is required for the mass production product inspection application. For example, regarding the reciprocating motion life of the movable part, it is sufficient to assume about 20 operations a day on average for diagnosis and maintenance of mechanical equipment.
Assuming use for 300 days a year and 10 years, a reciprocating movement life of 60,000 times is sufficient. On the other hand, for inspection of mass-produced products, it is assumed that inspection is performed once a minute, and 10 days a day.
Assuming time, 300 days a year and 10 years of use, 1
A reciprocating movement life of 800,000 times is required.

[0006] As a result of the experiment, in order to ensure the reciprocating motion life of the movable portion usable for the inspection of mass-produced products, the movable portion and the other fixed portion for deriving a detection signal from the vibration detecting element to the outside are required. Has been found to be the most problematic. The simplest and least costly method of electrically connecting the movable part and the fixed part is to connect them using a lead wire (a conductive wire with an insulating coating). In Japanese Utility Model Laid-Open Publication No. 4-75923, the movable part and the fixed part are connected by a lead wire. In order to prevent the lead wire and the soldered portion at the base of the lead wire from being repeatedly broken and stretched, the present inventors have made various attempts to prevent stress from being concentrated at a specific location, and despite the fact that the lead wire has been repeatedly devised, It could not be bent or stretched more than 100,000 times without disconnection.

According to the present invention, an extremely large number of times (for example, when the electrical connection means between the movable part and the fixed part of the vibration detecting device used for the inspection application of mass-produced products is applied to the application)
The present invention has been made based on the discovery of a new problem that it is necessary to prevent disconnection even by bending and stretching of 1 million times or more. More generally, the present invention is directed to a movable portion and a fixed portion that are brought into contact with a vibrating object. It is an object of the present invention to provide a vibration detecting device which has an electrical connection means between the lead wire and the lead wire, which is relatively superior in bending / stretching durability and has a longer life.

[0008]

In order to achieve the above object, a vibration detecting apparatus according to the present invention comprises a fixed part, a movable part which is movable with respect to the fixed part and which vibrates upon contact with a vibrating object when vibration is detected. A vibration detecting device having a movable portion and a vibration detecting element for converting vibration into an electric signal, wherein the fixed portion and the movable portion are electrically connected by a flexible printed circuit board. A detection signal from the vibration detection element or an analysis signal thereof is derived to the outside through the interface.

In this configuration, since the fixed portion and the movable portion are electrically connected by the flexible printed circuit board, the wire is not disconnected by a large number of bending and elongation as compared with the case where the fixed portion and the movable portion are connected by the lead wire. As a result, the number of lifespan of the reciprocating motion of the movable portion can be improved. Here, the flexible printed wiring board is one in which a conductor wiring pattern is provided on a sheet-like base material made of resin or the like, and in many cases, the conductor wiring pattern is further covered with an insulating protective layer. .

The vibration detecting device according to the present invention has at least a function of converting vibration into an electric signal, and may further have means for analyzing a vibration waveform signal.

[0011] In a preferred embodiment, the flexible printed wiring board has a relatively wide portion and a narrow portion in a portion bridged between the fixed portion and the movable portion. When the flexible printed wiring board is bent with the movement, a portion where the radius of curvature of the bending becomes relatively small is a wide portion. Then, the wide portions of the flexible printed wiring board can prevent the radius of curvature of these portions from being excessively reduced. The strength of the base material of the wiring board is also increased, so that the entire board is less likely to break.

In another preferred embodiment, the vibration detecting device is provided when the flexible printed wiring board is bent in a direction opposite to a predetermined direction (a direction intended in design) with the movement of the movable portion. And a guide portion that contacts the flexible printed wiring board and guides the bending direction of the flexible printed wiring board in a predetermined direction. Then, the bending state of the flexible printed wiring board with reproducibility can be ensured every time the movable section reciprocates, and it is possible to prevent the bending durability of the flexible printed wiring board from being lowered due to an unintended bending habit.
In addition, since a predetermined bending state can be automatically realized by the movement of the movable part without considering the initial bending state of the flexible printed wiring board immediately after the vibration detecting device is assembled, the vibration detection can be performed. Assembly of the device is also facilitated. Here, the guide portion may be a part of the movable portion or the fixed portion, or may be a part of the biasing portion when the guide portion has a biasing portion for biasing the movable portion against the fixed portion. Is also good.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. What is described here is a vibration detection device that has a function of converting vibration into an electric signal, but does not include means for analyzing a vibration waveform signal. From such a function, the vibration detecting device of this embodiment is referred to as a sensor head.

FIG. 1 is a front view of the sensor head 30, and FIG. 2 is a left side view thereof. The sensor head 30 has a substantially cylindrical shape, and the cable 15 is drawn out from the right end in FIG. 1, and the movable part 31 protrudes from the left end. The movable portion 31 described here is a portion that is pressed against the object to be measured for vibration, and moves rightward in accordance with a force applied to the tip from the left. A screw is engraved on the outer periphery of a region near the left end of the sensor head 30. The screw and the two nuts 23 are used to fix the sensor head to a structure (not shown) that supports the sensor head 30 (for example, a robot arm).

FIG. 3 is a sectional view taken along line AA of FIG. 2, and FIG.
FIG. 7 is a sectional view taken along line BB of FIG. Describing the internal structure of the sensor head 30, the fixing portion includes the housing 3 and a portion fixed thereto. The movable section 31 includes a base 5, a head chip 1, a spring seat 7, and the like. The movable portion 31 is provided to be movable in the axial direction of the housing 3 while receiving a leftward force by compressing the spring 8. A printed circuit board 16 on which a piezoelectric element as a vibration detecting element and an amplifier circuit for an output signal of the piezoelectric element are mounted on the base 5 of the movable portion 31.
Are attached by a female screw 17 and a rivet 20. The head chip 1 is made of stainless steel and is press-fitted and fixed to a base 5 made of aluminum. The spring seat 7 is locked by a pin 22 after being fitted to the base 5. One end of the spring 8 is in contact with the spring seat 7 of the movable portion 31, and the other end is in contact with the spring seat 9. The spring seat 9 is fixed to the housing by being sandwiched between a step on the inner surface of the housing 3 and a cap 11 screwed and fixed to the housing 3, and is prevented from rotating by a pin 22.

Ring-shaped rubber dampers 4 and 6 are provided between the base 5 and the housing 3. The rubber dampers 4 and 6 prevent the movable portion 31 from moving in a direction other than the axial direction of the housing 3 and prevent the vibration from being transmitted to the piezoelectric element when the housing 3 is subjected to external vibration. I have. The rubber damper 4 is fixed by being sandwiched between a step on the inner surface of the housing 3 and the cap 2 pressed into the housing. When the base 5 moves to the left, it hits the step of the base 5 and stops. Relieve the impact when. The rubber damper 6 is fixed by being sandwiched between the step portion of the base 5 and the spring seat 7, and forms a part of the movable portion.

Flexible printed wiring board (FPWB)
That. ) 21 is the printed circuit board 16 of the movable portion 31
And the cable 15 are electrically connected. One end of the FPWB 21 is soldered to the printed circuit board 16 and fixed by crimping to the base 5 with rivets 20, and the other end is soldered to the connector 10 attached to the end of the cable 15. The connector 10 is fitted into a groove provided in the spring seat 9, and is fixed to the spring seat 9 by a pressing rubber 25. The cable 15 is penetrated and fixed to the cap 11 via the bush 13 and the clamp 14.

FIG. 5 shows an equivalent circuit of the piezoelectric element and the amplifier circuit mounted on the printed circuit board 16. When a force is applied to the piezoelectric element, charges are charged, and the charges are converted into a voltage by a charge amplifier, which is a kind of integrator. In FIG. 5, -A is the amplification degree of the operational amplifier (A≫1), Cd is the capacitance of the piezoelectric element, Cc is the stray capacitance of the circuit, Cf is the feedback capacitance, Rf is the feedback resistance, and qd is the charge generated by the piezoelectric element. , qf the electrical charge to be stored in Cf, q ₀ represents the electric charge to be stored in Cd and Cc. At this time, the relationship e ₀ = − (qf / Cf) · (A / (1 + A)) ≒ −qf / Cf ≒ −qd / Cf holds, and the output voltage is proportional to the charge qd generated by the piezoelectric element. e ₀ is obtained.

When a product inspection is performed using the sensor head 30, the sensor head 30 is attached to a support structure such as a robot arm using the screw portion on the outer periphery of the housing 3 as described above, and Tip (head chip 1)
Can be pressed against and released from the product to be inspected. The product to be inspected is, for example, a laser beam printer, and the sensor head 30 analyzes the vibration generated by the rotation of the polygon mirror inside the laser beam printer to determine whether the product is normal or abnormal. Used for detection. When the product to be inspected is transported to a predetermined inspection position, the tip of the movable portion 31 of the sensor head 30 is pressed against a location suitable for detecting the vibration of the product, and the vibration is detected. When the vibration detection is completed, the sensor head 30 is separated from the product, and then the sensor head 30 waits until the next product to be inspected is conveyed.

Next, the vibration detecting operation by the sensor head 30 will be described. When the tip of the movable part 31 is pressed against the product to be inspected, the movable part 31 moves rightward in FIG. The limit of the movement is until the spring seat 7 and the spring seat 9 come into contact with each other. The amount by which the sensor head 30 is pressed against the product to be inspected is determined so that the movable portion 31 moves to approximately the middle of the movable distance when the vibration is detected. The boundary between head chip 1 and base 5 is cap 2
Matching with the end face of indicates that the pressing amount is appropriate. When detecting the vibration, the vibration of the product to be inspected is transmitted to the piezoelectric element via the head chip 1, the base 5, and the printed circuit board 16, where it is converted into an electric charge. The charge amount corresponding to this vibration is converted into a voltage by the charge amplifier, and this voltage signal is transmitted to the FPWB 21 and the cable 15.
, And provided to a device for analyzing vibration (not shown). The power required for the operation of the circuit on the printed circuit board 16 is supplied from a device for analyzing vibration via the cable 15 and the FPWB 21.

FIG. 6 shows a state in which the movable part 31 is pushed to the middle of the movable distance, and FIG. 7 shows a state in which the movable part 31 is pushed to the limit of movement. The FPWB 21 is bent as shown in each state.

FIG. 8 shows the shape of the FPWB 21. FPW
B21 is obtained by forming a copper foil wiring pattern on a polyimide resin sheet and covering the wiring pattern with an insulating layer.
In FIG. 8, the left part is a part to be attached to the printed circuit board 16, and the right part is a part to be attached to the connector 10. The width of the middle portion between the two mounting portions is not uniform, but the portion 21a near the mounting portion to the connector and the center 2
1b is thicker. Since these two locations are where the bending concentrates when the movable portion 31 is pushed in as shown in FIGS. 6 and 7, by making these portions thicker, the radius of curvature of the bending of these portions is reduced. By preventing the conductor pattern from becoming excessively small, the conductor pattern is prevented from being broken at these portions, and the FPWB 21 itself is prevented from being broken.

In FIG. 3, the FPWB 21 is in a slightly bent state.
A space where the PWB 21 can freely bend is provided, and only a narrow space that prevents free bending is provided below the FPWB 21. The fact that the spring seat 9, the relief groove of which is cut upward, the cylindrical structure of the spring seat 7, and the FPWB 21 are disposed below the axis of the housing 3,
This causes a difference in the size of the space above and below B21.
Therefore, when the movable part 31 is pushed in, if FP
Even if the WB 21 is bent downward first, the downward movement of the FPWB 21 is hindered by the spring seat 9, the spring seat 7 or the spring 8. The bend turns upward.
It can be said that the spring seat 9, the spring seat 7, or the spring 8 functions as a guide mechanism for bending the FPWB 21 upward. Once the bending of the FPWB 21 becomes convex upward, F
Even in the state of FIG. 3 in which the PWB 21 is the most stretched, the slightly upwardly convex state is maintained, and thereafter, the central portion of the FPWB 21 always moves upward in response to the pushing of the movable portion 31, FPWB2 as intended at the time of design
1 is ensured. Thereby, the FPWB 21
FPWB 21 can be prevented from being degraded due to unintended bending habits.

As a result of the experiment, no abnormality occurred in the FPWB 21 even when the FPWB 21 was bent and stretched (reciprocating motion of the movable portion) three million times, and it was confirmed that the sensor head 30 could be sufficiently used for inspection of mass-produced products.

The embodiment of the present invention described above can be variously modified. For example, various elastic structures such as a leaf spring may be used as means for biasing the movable portion with respect to the fixed portion, in addition to a helical spring such as the spring 8. In addition, when the tip of the movable portion is a magnet and the magnetic force can ensure contact with the vibrating object, the urging means may be omitted. Further, the amplifier circuit for the output signal of the vibration detecting element may be provided on the fixed part side. Further, means such as a microcomputer system for analyzing a vibration waveform signal may be incorporated in the sensor head.

[Brief description of the drawings]

FIG. 1 is a front view of a vibration detection device (sensor head) according to an embodiment of the present invention.

FIG. 2 is a left side view of the same.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a sectional view taken along line BB of FIG. 2;

FIG. 5 is an equivalent circuit diagram of a piezoelectric element and an amplifier circuit mounted on a printed circuit board.

FIG. 6 is a cross-sectional view showing a state where the movable unit is pushed to the middle of the movable distance.

FIG. 7 is a cross-sectional view showing a state in which the movable unit has been pushed down to a movable limit.

FIG. 8 is a front view of a flexible printed wiring board.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Head chip (movable part) 3 Housing (fixed part) 5 Base (movable part) 16 Printed circuit board (mounted with vibration detecting element) 21 Flexible printed wiring board (FPWB) 30 Sensor head 31 Movable part

Claims (3)

[Claims] 1. A vibration detecting device comprising: a fixed portion; and a movable portion movable with respect to the fixed portion and vibrating by contacting a vibrating object when detecting vibration, wherein the movable portion converts the vibration into an electric signal. In the vibration detecting device provided with the element, the fixed part and the movable part are electrically connected by a flexible printed wiring board, and a detection signal by the vibration detecting element or an analysis signal thereof is externally connected through the flexible printed wiring board. A vibration detection device characterized in that the vibration detection device is derived. 2. The flexible printed circuit board according to claim 1,
In a portion bridged between the fixed portion and the movable portion, the portion has a relatively wide portion and a narrow portion,
2. The portion having a relatively small radius of curvature when the flexible printed wiring board is bent with the movement of the movable portion is the wide portion. 3. Vibration detection device. 3. When the flexible printed wiring board is bent in a direction opposite to a predetermined direction as the movable portion moves, the flexible printed wiring board comes into contact with the flexible printed wiring board and is bent. The vibration detecting device according to claim 1, further comprising a guide unit that guides the direction in a predetermined direction.