JP3451534B2 - Vibration detector - Google Patents

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 contacting a vibrating object to convert the vibration into an electric signal and detecting the vibrating state of the vibrating object.

[0002]

2. Description of the Related Art Conventionally, as this type of vibration detecting device,
As shown in Japanese Utility Model Publication No. 5-24025, one in which the entire vibration detecting device is directly screwed and fixed to a vibrating object,
As disclosed in Japanese Patent Laid-Open No. 5-126622, there is known a device in which a vibration detection device is held by hand and pressed against a vibrating object for use. In addition, among those used by pressing the vibration detecting device against the vibrating object, there is an actual open flat wire 4-7592.
As shown in Japanese Patent Laid-Open No. 3 (1994), a portion to be pressed is a movable portion urged by a spring, and it is known that the movable portion is provided with a piezoelectric element.

It is assumed that these vibration detecting devices will be used for diagnosis and maintenance of mechanical equipment, judging from the description in the above publication and how the vibration detecting devices on the market to date are used. . That is, the method of directly screw-fastening to the vibrating object is to be permanently installed in the mechanical equipment to monitor its abnormal vibration, and the pressing type is to be carried by the maintenance personnel of the mechanical equipment to be diagnosed. It is for inspecting equipment and going around.

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

[0005]

Regarding the characteristics required for the vibration detecting device, the vibration detecting device according to the present invention is assumed to be used for the diagnosis and maintenance of mechanical equipment assumed by the conventional pressing type vibration detecting device. There is a marked difference in the durability required for the movable part of the vibration detection device from the case of mass production product inspection applications, and a much higher level of durability is required for mass production product inspection applications. For example, regarding the reciprocating motion life of the movable part, it is sufficient to assume about 20 movements per day on average for diagnostic / maintenance applications of mechanical equipment,
Assuming use of 300 days a year for 10 years, a reciprocating motion life of 60,000 times will be sufficient. On the other hand, for inspection of mass-produced products, 10 times a day
Assuming usage of 300 hours per year for 10 years, 1
A reciprocating motion life of 800,000 times is required.

As a result of the experiment, in order to secure the reciprocating motion life of the movable part that can be used for the inspection of mass-produced products, the movable part and the fixed part other than the movable part for deriving the detection signal by the vibration detecting element to the outside are provided. It turned out that the structure that electrically connects the two is the most problematic. The simplest and least costly method of electrically connecting the movable part and the fixed part is to connect using a lead wire (a conductor wire with an insulating coating). Also in Japanese Utility Model Laid-Open No. 4-75923, the movable portion and the fixed portion 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 broken by repeated bending and stretching, the inventors have made various efforts to prevent stress from concentrating on a specific location, but It could not be bent or stretched more than 100,000 times without breaking.

According to the present invention, the electrical connection means between the movable portion and the fixed portion of the vibration detecting device used for the inspection application of mass-produced products is applied to the application for a very large number of times (for example,
The present invention has been made based on the discovery of a new problem that it is required not to be broken even after bending and stretching of 1 million times or more). More generalized, the present invention is to provide a movable part and a fixed part which are brought into contact with a vibrating object. It is an object of the present invention to provide a vibration detecting device having a longer life by making the electrical connecting means between and to have relatively excellent bending and stretching durability as compared with the case of using a lead wire.

[0008]

In order to achieve the above object, a vibration detecting apparatus according to the present invention comprises a fixed portion and a movable portion which is movable with respect to the fixed portion and contacts a vibrating object to vibrate when vibration is detected. In a vibration detecting device having a movable part and a vibration detecting element for converting vibration into an electric signal, the flexible printed wiring board electrically connects the fixed part and the movable part to each other. so as to derive the detection signal or the analysis signal by vibration detecting element to the outside through a flexible with the movement of the movable portion
If the sibble printed wiring board is in a certain direction (design
Flexing direction, the flex
Flexible printed board
Flexible cable that guides the bending direction of the wiring board in a predetermined direction.
The flexible printed wiring board may bend in the specified direction.
It is provided with a guide portion provided with an open space .

In this structure, since the fixed portion and the movable portion are electrically connected by the flexible printed wiring board, there is no disconnection due to a large number of times of bending and bending, as compared with the case where they are connected by lead wires. As a result, the number of reciprocating motions of the movable part can be improved. Here, the flexible printed wiring board is a sheet-shaped base material made of resin or the like on which a conductor wiring pattern is provided, and in many cases, the conductor wiring pattern is further covered with an insulating protective layer. . Moreover, for moving the movable part
Accordingly, the flexible printed wiring board is
It will guide you in the direction you intend to count, so the moving parts will move back and forth.
Flexible printed wiring board that is reproducible with every movement
The bending state of the plate can be secured and an unintended bending tendency
Flexibility of flexible printed wiring board
Can be prevented from decreasing. Also, a set of vibration detection devices
First flexible printed wiring board immediately after assembly
Even if you do not pay attention to the predetermined flexure condition
A predetermined bending state can be automatically realized by the motion of the moving part
Therefore, the vibration detection device can be easily assembled. here,
The guide part may be a part of the movable part or the fixed part,
When having a biasing means for biasing the movable part with respect to the fixed part
May be part of the biasing means.

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 a means for analyzing a vibration waveform signal.

In a preferred embodiment, the flexible printed wiring board has a relatively wide portion and a narrow portion in a portion bridging between the fixed portion and the movable portion, When the flexible printed wiring board is bent along with the movement, the portion where the bending radius of curvature becomes relatively small is the wide portion. Then, it is possible to prevent the bending radius of curvature of these portions from becoming excessively small due to the wide portions of the flexible printed wiring board, so that it becomes difficult for the conductor pattern to break at these portions, and at the same time, the flexible printed circuit board becomes flexible. The strength of the base material of the wiring board is also increased, and the entire board is less likely to break.

[0012]

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. Described herein is a vibration detection device that has the function of converting vibration into an electrical signal, but does not include means for analyzing the vibration waveform signal. Due to such a function, the vibration detection 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 pulled out from the right end portion in FIG. 1 and the movable portion 31 projects from the left end portion. The movable portion 31 described here is a portion that is pressed against an object whose vibration is to be measured, and moves to the right according to the force applied from the left to the tip thereof. A screw is engraved on the outer periphery of the area 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 (for example, a robot arm) (not shown) that supports the sensor head 30.

FIG. 3 is a sectional view taken along the line AA of FIG. 2, and FIG.
FIG. 6 is a sectional view taken along line BB of FIG. The internal structure of the sensor head 30 will be described. The fixing portion includes the housing 3 and a portion fixed to the housing 3. The movable portion 31 includes a base 5, a head chip 1, a spring seat 7, and the like. The movable portion 31 is provided movably in the axial direction of the housing 3 while receiving a leftward force by compressing the spring 8. A printed circuit board 16 having a piezoelectric element, which is a vibration detecting element, and an amplifier circuit for the output signal thereof is mounted on the base 5 of the movable portion 31.
Are attached by a 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 fitted to the base 5 and then prevented from rotating by a pin 22. 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 part 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 vibrated from the outside. There is. The rubber damper 4 is sandwiched and fixed between the step on the inner surface of the housing 3 and the cap 2 press-fitted into the housing, and when the base 5 moves to the left, it hits the step surface of the base 5 and the base 5 stops. Alleviates the impact of when. The rubber damper 6 is sandwiched and fixed by the stepped portion of the base 5 and the spring seat 7, and constitutes a part of the movable portion.

Flexible printed wiring board (FPWB
Say. ) 21 is the printed circuit board 16 of the movable part 31.
And the cable 15 are electrically connected. One end of the FPWB 21 is soldered to the printed circuit board 16 and crimped and fixed to the base 5 by the rivet 20, and the other end is soldered to the connector 10 attached to the end of the cable 15. The connector 10 is fitted in 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 fixed to the cap 11 through the bush 13 and the fastening member 14 so as to pass therethrough.

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, an electric charge is charged, and this electric charge is converted into a voltage by a charge amplifier which is a kind of integrator. In Figure 5, -A is the amplification 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 represents the charge stored in Cf, and q ₀ represents the charge stored in Cd and Cc. At this time, the relationship of e ₀ = − (qf / Cf) ・ (A / (1 + A)) ≈−qf / Cf≈−qd / Cf holds, and the output voltage proportional to the electric charge qd generated by the piezoelectric element. e ₀ is obtained.

When a product inspection is performed using this sensor head 30, the sensor head 30 is attached to a supporting structure such as a robot arm using the screw portion on the outer periphery of the housing 3 as described above, and the movable portion 31 is moved. Tip (head chip 1)
To be able to press and release the product to be inspected. The inspection target product 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 conveyed to a predetermined inspection position, the tip of the movable portion 31 of the sensor head 30 is pressed against a place 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 inspection target product 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 to the right 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 pressing amount of the sensor head 30 against the product to be inspected is determined so that the movable portion 31 moves to approximately the middle of the movable distance when vibration is detected. The boundary between the head chip 1 and the base 5 is the cap 2.
Matching with the end face of is a guide for proper pressing amount. When the vibration is detected, 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, and is converted into the amount of electric charge there. The charge amount corresponding to this vibration is converted into a voltage by the charge amplifier, and this voltage signal is applied to the FPWB 21 and the cable 15.
And is provided to a device for analyzing vibrations (not shown). The power required to operate the circuit on the printed circuit board 16 is supplied from a device for analyzing vibrations via the cable 15 and the FPWB 21.

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

FIG. 8 shows the shape of the FPWB 21. FPW
B21 is a wiring pattern of copper foil formed on a sheet of polyimide resin, and the wiring pattern is covered with an insulating layer.
In FIG. 8, the left side is the mounting portion to the printed circuit board 16, and the right side is the mounting portion to the connector 10. The middle portion of both mounting portions is not uniform in width, and the portion 21a in the vicinity of the mounting portion to the connector and the portion 2 slightly to the right of the center of the whole
1b is thicker. These two places are places where bending is concentrated when the movable part 31 is pushed in as shown in FIGS. 6 and 7. Therefore, by making these parts thicker, the bending radius of curvature of these parts becomes larger. The conductor pattern is prevented from breaking at these portions by preventing it from becoming excessively small, and the FPWB 21 itself is prevented from breaking.

In FIG. 3, the FPWB 21 is in a slightly bent state. At this time, F is above the FPWB 21.
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 with the escape groove cut upward, the cylindrical structure of the spring seat 7 and the FPWB 21 are arranged below the axis of the housing 3 are
The size of the space above and below B21 is different.
Therefore, if the movable part 31 is pushed in, if FP
Even if the WB 21 is first bent downward, when the downward movement of the FPWB 21 is obstructed by the spring seat 9, the spring seat 7 or the spring 8, and the pushing of the movable portion 31 reaches a certain amount, the FPWB 21 Bends to a convex shape.
It can also be said that the spring seat 9, the spring seat 7 or the spring 8 acts as a guide mechanism for bending the FPWB 21 in a convex shape. Once the bending of FPWB21 is convex upward, F
Even in the state in which the PWB 21 is in the most extended state as shown in FIG. 3, the state in which the PWB 21 is slightly convex upward is maintained, and thereafter, the central portion of the FPWB 21 always moves upward with respect to the pushing of the movable portion 31, FPWB2 as intended at the time of design
The bending state of 1 is secured. As a result, FPWB21
It is possible to prevent the bending durability of the FPWB 21 from being lowered due to an unintended bending tendency.

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 part) 3 million times, and it was confirmed that the sensor head 30 can be sufficiently used for inspection of mass-produced products.

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

[Brief description of 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.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view taken along line BB in FIG.

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 in which the movable portion is pushed to the middle of the movable distance.

FIG. 7 is a cross-sectional view showing a state in which the movable portion is pushed to the limit of its movement.

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 (on which a vibration detecting element is mounted) 21 flexible printed wiring board (FPWB) 30 sensor head 31 movable part

   ─────────────────────────────────────────────────── ─── Continued front page       (56) Reference JP-A-6-82301 (JP, A)                 JP-A-9-38086 (JP, A)                 Actual Kaihei 4-75923 (JP, U)                 Special table flat 9-506701 (JP, A)

Claims (2)

(57) [Claims] 1. A vibration detector that includes a fixed portion and a movable portion that is movable with respect to the fixed portion and that vibrates by contacting a vibrating object at the time of detecting a vibration, wherein the movable portion converts the vibration into an electric signal. In a vibration detection device including an element, a flexible printed wiring board electrically connects the fixed portion and the movable portion, and a detection signal by the vibration detection element or an analysis signal thereof is externally transmitted through the flexible printed wiring board. so as to derive the said flexible printed wiring in accordance with the movement of the movable portion
When the wire board is bent in the opposite direction
In contact with the flexible printed wiring board,
Bend the flexible printed wiring board in a predetermined direction
The flexible printed wiring board
Guide section with a space that can be bent in the direction of
A vibration detecting device characterized in that it is provided . 2. The flexible printed wiring board,
In the portion bridging between the fixed portion and the movable portion, having a relatively wide portion and a narrow width portion,
2. The wide portion is a portion where the radius of curvature of bending is relatively small when the flexible printed wiring board is bent along with the movement of the movable portion. Vibration detection device.