JPH0692980B2 - Vibration measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vibration measuring device, and more particularly, to a change in physical quantity, for example, vibration, which can be detected by an optical detecting means.

[Outline of Invention]

According to the present invention, in a vibration measuring device, a movable body holding a condenser lens is arranged so as to be displaced in a direction orthogonal to a light source light according to a physical quantity to be measured, and photoelectric conversion is performed according to the displacement. Since the physical quantity is measured based on the displacement of the optical spot generated on the element, a vibration measuring device with higher performance can be realized with a practically simple structure.

[Conventional technology]

Conventionally, as a vibration measuring device, a device having a structure in which a displacement of a pendulum is optically detected has been proposed.

For example, as shown in FIG. 18, the light source light LA1 is applied to the rod-shaped pendulum 1 and its image 2 is projected so as to straddle the pair of light-receiving elements 3A and 3B, and thus the rod-shaped pendulum 1 is indicated by an arrow. When it is displaced in the direction orthogonal to the light source light LA1 as indicated by a, it is possible to obtain a light detection output that changes in accordance with the displacement amount of the rod-shaped pendulum 1 from the pair of light receiving elements 3A and 3B (special feature). (Kaisho 60-205370 publication).

Further, as shown in FIG. 19, a hinge portion 13 is formed by piercing a through hole 12 in the diameter direction in the middle of the hollow pipe 11, and the center of the hollow pipe 11 is formed at an end 11A fixed to a fixing portion 14. A structure having a light source 15 for emitting the light source light LA2 in the axial direction is proposed (Japanese Patent Laid-Open No. 62-233770).

Thus, the free end of the hollow pipe 11 closer to the tip than the hinge 13 is
11B is adapted to vibrate in the direction of arrow b, and the light source L
A2 passes through a condenser lens 15 provided coaxially with the free end portion 11B to focus it on a pair of light receiving elements 16A and 16B.

In the configuration of FIG. 19, when the free end portion 11B vibrates in the direction of the arrow b around the hinge portion 13, the light receiving elements 16A and 16B.
By changing the position of the irradiation light beam LA3 with respect to A, the photoelectric conversion outputs of the light receiving elements 16A and 16B change, and thus the vibration of the free end portion 11B can be detected.

[Problems to be solved by the invention]

However, according to the conventional configuration of FIG. 18, the light receiving element 3A and
Since the size of the shadow image projected on 3B cannot be made as small as practically necessary, there is a problem that the detection sensitivity cannot be increased.

Due to the displacement of the rod-shaped pendulum 1, a pair of light receiving elements 3A and 3B
It is considered that the change in the irradiation area caused by the fact that the size of the image 2 formed on the light receiving elements 3A and 3B becomes sharper in response to the change in the size of the image 2 and the detection sensitivity can be improved. According to the configuration shown in FIG. 18, the size of the image 2 depends on the size of the rod-shaped pendulum 1, and therefore cannot be arbitrarily reduced.

On the other hand, according to the conventional configuration of FIG.
The irradiation light beam LA3 irradiated to A and 16B can be sufficiently focused in practical use by the condenser lens 15, and the detection sensitivity can be improved accordingly.

However, according to this configuration, since the free end 11B provided with the condenser lens 15 rotates about the hinge portion 13 in response to the vibration, the optical axis of the condenser lens 15 as shown in FIG.
There is a drawback that L ₀ rotates to a position that does not match the light source 15.

The light source 15 and the light receiving element 16 are located at the focal position of the condenser lens 15.
When A and 16B are provided, when the optical axis L ₀ rotates and the condenser lens 15 is displaced by δx ₀ in the direction orthogonal to the optical axis L ₀ , the light on the light receiving surfaces of the light receiving elements 16A and 16B The displacement amount of the axis L ₀ becomes 2δx ₀ . But light Supotsuto the irradiation light beam LA3 generated at the focal point when the condensing lens 15 is rotated so as to tilt the optical axis L ₀ is to return to the inside from the spectral axis L ₀ with inclined optical axis L ₀ distance .delta.x ₁ After being displaced, the optical spot of the irradiation light beam LA3 is eventually moved by Δx ₂ from the optical axis L ₀ passing through the light source 15.

As described above, since the optical axis L ₀ of the condenser lens 15 is tilted, the displacement amount generated in the irradiation light beam LA3 is reduced by the distance Δx ₁ , and the detection sensitivity is deteriorated accordingly.

The present invention has been made in consideration of the above points, and in obtaining an electrical detection output corresponding to the amount of vibration based on the displacement of the condenser lens, the detection sensitivity is much higher, and the overall configuration can be minimized. It is intended to propose a vibration measuring device that is simple and can be miniaturized.

[Means for solving problems]

In order to solve such a problem, in the present invention, the optical axis is displaced in the first direction X in response to the amount of vibration to be measured, and the optical axis is in the second direction Y orthogonal to the first direction X. And a movable body 2 that holds a condenser lens 2B having a movable body 2 and a movable body 2 that extends in a third direction Z orthogonal to the first and second directions X and Y. Support 4 that is elastically supported so that it can be displaced, a light source 5 disposed on the optical axis L ₀₁ of the condenser lens 2B so as to face the condenser lens 2B, and a pair of photoelectric conversion elements 6A. , 6B, light source 5
The irradiation light beam LA12 obtained by converging the light source light LA11 emitted from the light source by the condensing lens 2B is received by the pair of photoelectric conversion elements 6A and 6B, and the irradiation light beam LA12 changes according to the displacement of the movable body 2. When the irradiation position is displaced by a pair of photoelectric conversion elements 6A and 6B, the photoelectric conversion unit 6 sends out a photodetection signal corresponding to the displacement amount, and the deviation of the photodetection signal sent from the photoelectric conversion unit 6 A vibration amount detection circuit unit 7 which outputs a vibration amount measurement output based on the vibration amount, and a displacement servo means 43 which generates a displacement suppressing force which is an electromagnetic force with respect to the movable body 2 based on the deviation of the light detection signal. With respect to the distance L between the light receiving surfaces of the photoelectric conversion elements 6A and 6B, the diameter D of the irradiation light beam LA12 is selected to a value that satisfies the relationship of L = 0.8D.

[Action]

The movable body 2 has a support 4 arranged in the third direction Z.
According to the amount of vibration to be measured in the first direction X, the movable body 2 is displaced to generate a pair of photoelectric light based on the light source light LA11 emitted from the light source 5. The irradiation position of the irradiation light beam LA12 focused by the condenser lens 2B on the conversion elements 6A and 6B is displaced along the first direction X.

As a result, a highly accurate photodetection signal can be obtained from the pair of photoelectric conversion elements 6A and 6B, and a vibration measurement output can be formed in the vibration amount detection circuit based on the deviation.

〔Example〕

With such a configuration, it is possible to configure a high-performance physical quantity measuring device with a simple configuration as a whole.

An embodiment of the present invention will be described in detail with reference to the drawings.

[1] Principle Configuration FIG. 1 shows the principle configuration of the optical detection unit 1 of the vibration measuring device, in which the movable body 2 is located in the space represented by the XYZ orthogonal coordinate system at the origin position and is indicated by an arrow c. It is arranged so that it can vibrate in the X-axis direction.

The movable body 2 is supported so that a lens barrel 2A holding a condenser lens 2B can be suspended from a fixed portion 3 via a support body 4 made of a leaf spring. The condenser lens 2B is arranged so that the optical axis L ₀₁ coincides with the Y-axis direction, and the support 4 moves the movable body 2 along the X-axis without changing the direction of the optical axis L ₀₁ of the condenser lens 2B. It is arranged in the Z-axis direction so that it can be displaced in any direction.

At the focal position of the condenser lens 2B, a light source 5 made of a semiconductor laser and a photoelectric conversion unit 6 having photodiodes 6A and 6B as a pair of photoelectric conversion elements are arranged so as to sandwich the condenser lens 2B. The photoelectric conversion outputs of 6A and 6B are sent to the vibration amount detection circuit unit 7 as a light detection signal S _DET , and the vibration amount measurement output S _OUT is sent based on the deviation.

Here, the semiconductor laser constituting the light source 5 is driven to emit light in the LED light emitting region (without being driven in the laser oscillation region), thereby forming a minute point light source.

The photodiodes 6A and 6B are arranged so as to be adjacent to each other in the direction along the X axis, and the light source light LA emitted from the light source 5 is emitted.
11 is focused by the condenser lens 2B as an irradiation light beam LA12 at the boundary position between the photodiodes 6A and 6B, and the optical spot SPT formed by the light image of the light source 5 is thus the condenser lens 2B, and hence the X axis of the movable body 2. It is configured to be displaced in the direction along the X axis by the displacement amount corresponding to the displacement amount in the direction.

Thus, from the state in which the condenser lens 2B forms the optical spot SPT at the boundary position P ₁ of the photodiodes 6A and 6B by the irradiation light beam LA12 as shown by the solid line in FIG.
When it is displaced by δx ₀ in the X-axis direction as shown by the broken line, the irradiation light beam LA12 emitted from the condenser lens 2B has a focal point at the boundary position P ₁ corresponding to the displacement amount δx ₀ of the condenser lens 2B. It moves to the displacement position P ₂ displaced by δx in the X-axis direction.

By the way, the displacement amounts P _{2 to} P ₁ = δx at this time are
B. Therefore, depending on the position of the movable body 2, as shown in FIG. Can be obtained by In the equation (1), a is the distance from the light source 5 to the condenser lens 2B, and b is the distance from the condenser lens 2B to the surfaces of the photodiodes 6A and 6B.

Here, the light source 5 and the photodiodes 6A and 6B are arranged at the focal position of the condenser lens 2B, and accordingly, the distances a and b are equal to each other as a = b (2) Under, the displacement amount δx on the photodiodes 6A and 6B is δx = 2δx ₀ (3).

Therefore, according to the configuration of FIG. 1, as described above with reference to FIG. 20, it is possible to detect the displacement amount with high detection sensitivity without the possibility of causing a problem that the detection sensitivity deteriorates.

[2] Improvement of linearity of displacement amount detection characteristics At the boundary position between a pair of photodiodes 6A and 6B mounted by the way, as shown in FIG. 4, an interval L (10 to 100 [μm ], The non-photoelectric conversion region 8 is interposed, the light source 5 actually has a finite size, and the condenser lens 2B has optical characteristics such as aberration.
The light spot SPT imaged on 6A and 6B has a predetermined spot diameter D, and the relative size relation between the spot diameter D of this light spot SPT and the interval L of the non-photoelectric conversion region 8 is used. The photoelectric conversion output obtained from the photo diodes 6A and 6B is determined.

That is, as shown in FIG. 4, the optical spot SPT is displaced from the state in which the condenser lens 2B is located at the reference position having the center at the center position of the non-photoelectric conversion region 8 and the distance as shown in FIG. Irradiation luminous flux LA received by the photodiodes 6A and 6B when moved to the photodiode 6A side by δx
The change of the light intensity of 12 is the light spot SPT photo diode 6
Proportional to the rate of increase or decrease of the overlapping area on A and 6B.

That is, as shown in FIG. 6, when the light spot SPT is displaced toward the photodiode 6B side in the direction along the X-axis from the position shown by the solid line in the direction along the X axis, the light amount change rate dE _B / d ( δx) is become. In addition, the light quantity change rate dE _A / d (δx) generated in the other photodiode 6A is Can be asked for.

Therefore, the light amount change rate dE / d (δx) expressed by the equations (4) and (5) is calculated as shown in FIG.
If is plotted as a curve along the horizontal axis, the photo diode SPT is displaced from the reference position (ie, the position of δx = 0) in the direction of the photo diode 6B (or 6A).
It is possible to read the relative change in photoelectric conversion output generated in 6B and 6A.

In FIG. 7 (A), the light amount change rate of the photodiode 6B
dE _B / d (δx) is the displacement amount δ of the center point CT of the optical spot SPT
x is , The optical spot SPT is in the non-photoelectric conversion area 8
Since it is in the state of irradiating with, it exhibits a change like drawing a semicircle as represented by the equation (4).

On the other hand, the displacement amount δx is When the size of the optical spot SPT becomes 6
It means that the position is shifted in the direction of the photodiode 6A to a position where B cannot be irradiated, and at this time, the light quantity change rate dE _B / d (δx) is become.

In addition, the center point CT of the optical spot SPT When the light spot SPT has been displaced until, the light spot SPT leaves the non-photoelectric conversion region 8 and is displaced on the photodiode 6B. At this time, the light quantity change rate dE _B / (δx) is It becomes 0 like.

Similarly, the rate of change in the amount of light with respect to the photodiode 6A dE _A /
Considering d (δx), the displacement amount δx is In the range of, since the light spot SPT is illuminating the non-photoelectric conversion area 8, the light quantity change rate dE _A /
d (δx) changes so as to draw a semicircle as expressed by the equation (5).

The displacement amount δx is Then, the optical spot SPT is displaced in the direction of the photodiode 6A to a position where the non-photoelectric conversion area 8 is not illuminated, and at this time, the light quantity change rate dE _A / d (δx) is become.

Also, the displacement amount δx of the optical spot SPT is determined by the photo diode 6B.
In the direction of When it is displaced to the area of, the optical spot SPT is displaced to a position where the photodiode 6A cannot be irradiated,
At this time, the light quantity change rate dE _A / d (δx) is become.

From the result of FIG. 7 (A), the displacement amount δx is When it is in the area AR _AB , the light spot SPT is illuminating both the photodiodes 6A and 6B, and therefore the light quantity change rate dE / d when viewed as the photoelectric conversion element 6 as a whole.
As shown in FIG. 7 (B), the total characteristic of (δx) is the light quantity change rate dE _A / d (δx) and d of the photodiodes 6A and 6B.
It can be expressed as the sum of E _B / d (δx).

On the other hand, the displacement amount δx is The light quantity change rates dE / d (δx) occurring in the areas _{A RA} and AR _{B of} are represented by the light quantity change rates dE _A / d (δx) and dE _B / d (δx) occurring only in the photodiodes 6A and 6B, respectively. be able to.

From the relationship of FIG. 7 (B), in order to realize the linearity as good as the detection characteristics of the photodiodes 6A and 6B, the comprehensive characteristic of the light quantity change rate [dE / d ( δx)] _SUM = dE _A / d (δx) + dE _B / d (δx)
However, it is desirable to maintain a practically constant value in the effective displacement range of the displacement amount δx. In order to satisfy such a condition, the optical spot with respect to the interval L between the non-photoelectric conversion regions 8 is required. The diameter D of the SPT may be selected as an optimum value as necessary.

Under the condition that the relation between the distance L between the non-photoelectric conversion regions 8 and the diameter D of the optical spot SPT is selected as L <D (19), the diameter D is changed as shown in FIG. 8 (A). If the distance L is approached, as shown in FIG. 8 (B), the light amount change rate dE _A / d (δ of the photodiodes 6A and 6B is obtained.
x) and dE _B / d (δx) overlap area AR _AB becomes narrower, and as a result, as shown in FIG. 8 (C), it corresponds to area AR _AB in the total light intensity change rate [dE / d (δx)] _SUM . There is a tendency that the value of the part to do becomes smaller.

In addition to this, as shown in FIG.
When the value is reduced to a value approximately equal to, the light intensity change rate dE / d
(Δx) is a photodiode as shown in FIG. 9 (B).
6A and 6B light intensity change rate dE _A / d (δx) and dE _B / d (δx)
A region where the overlapping areas AR _AB disappear and the areas AR _A and AR _{B are} directly adjacent to each other is obtained, and the total light amount change rate [dE / d (δx)] _{SUM at} this time is shown in FIG. ), The same characteristics as the light quantity change rate dE / d (δx) (FIG. 9 (B)) are exhibited.

When the diameter D of the light spot SPT is further reduced and the diameter D is selected to be smaller than the interval L as shown in FIG. 10 (A), the characteristic of the light quantity change rate dE / d (δx) is shown in FIG. 10 (B). )
As shown in, the light quantity change rate dE of the photodiodes 6A and 6B
_A / d _(δx) and dE _B / d (δx) of the area AR _A and AR _B light amount change rate dE / d (δx) is zero between the regions, namely the dead zone
AR ₀ is generated, which results in a dead zone in the total light intensity change rate [dE / d (δx)] _SUM as shown in FIG. 10 (C).

From the examination of FIGS. 8 to 10, the photodiodes 6A and 6B are shown.
In order to make the rate of change in
As described above with respect to the equation (19), when the diameter D is selected to be larger than the interval L and the displacement amount δx is δx = 0, the light amount change rate dE / d (δx) is a predetermined value, that is, the photodiodes 6A and 6B. Change rate of light dE _A / d (δx) and dE _B / d (δ
It is considered that a linearly good measurement result can be obtained practically when the value is set to about 60% of x), and this can be confirmed by an experiment.

If the light amount change rate at the displacement amount δx is set as δx = 0 in the equations (4) and (5), Therefore, by applying the condition of 60% to this, The relationship is established.

Then, solving equation (21) for the interval L, L = 0.8D ... (22) If the interval L is selected to be 0.8 times the diameter D,
As shown in the figure (A), a dead zone area AR ₀ is provided between areas AR _A and AR _B where the light quantity change rates dE _A / d (δx) and dE _B / d (δx) of the photodiodes 6A and 6B do not overlap. The overlapping area AR _AB is formed without being generated, and the total light amount change rate [dE / d in the overlapping area AR _AB is shown in FIG. 11 (B).
(Δx)] It is possible to obtain a result in which the value of _SUM is approximately the same as the values of the other regions AR _A and AR _B , and thus, the detection optical with good linearity in the effective region of the displacement amount δx. A system can be realized.

As the photoelectric conversion element actually manufactured, the distance L between the photodiodes 6A and 6B is about L = 10 to 100 [μm], so that the diameter D of the optical spot SPT is 13
The light source 5 and the condenser lens 2B capable of focusing the irradiation light beam LA12 to about 130 [μm] are provided.

[3] Configuration of Vibration Measuring Device FIGS. 12 and 13 show an embodiment in the case where the acceleration detecting type vibration measuring device is applied to the present invention, and the same reference numerals are given to the portions corresponding to those in FIG. As shown, the vibration measuring device 21 detects the vibration based on the vibration acceleration given to the case 22 based on the operation principle described above with reference to FIGS. 4 and 5.

The case 22 is fixed with a first magnetic circuit member 24 formed by forming a columnar protrusion in the central portion of the disc-shaped base portion, and the second magnetic disc member and the second magnetic circuit member 24 formed of an annular ring are attached to the disc-shaped base portion. The magnetic circuit members 25 and 26 of FIG. 3 are fixed so as to be sequentially stacked on top of each other, and the support member 4 made of, for example, a leaf spring is moved downward by a pair of mounting members 27 and 28 projecting forward from the upper front surface of the magnetic circuit member 26. It is held by a cantilever so that it hangs down.

At the lower end of the support body 4, a movable body 2 having a cylindrical block structure is provided.
Is attached by the attachment member 31, and thus the movable body 2
According to the vibration of the case 22, the vibration can be displaced in the direction indicated by the arrow e, that is, in the direction of the central axis CENT of the case 2.

A through hole 35 having a circular cross section is formed in the movable body 2 so as to be orthogonal to the central axis CENT, and an aspherical lens is formed at a substantially central position in the longitudinal direction of the through hole 35 (for example, a position intersecting the central axis CENT). The constructed condenser lens 2B is fixed so that its optical axis L ₀₂ coincides with the center of the through hole 35.

As shown in FIG. 12, the light source 5 made of a semiconductor laser is attached to the front surface of the magnetic circuit member 26 by the attaching member 38 so as to face the left side opening of the through hole 35, and
A photoelectric conversion unit 6 having a pair of photodiodes 6A and 6B is fixed to the front surface of the magnetic circuit member 26 by a mounting member 40 so as to face the right end surface of the through hole 35.

Thus, the light source light LA21 emitted from the light source 5 is a condenser lens.
The photoelectric conversion unit 6 is condensed by 2B and emitted as a luminous flux LA22.
It is focused on the photodiodes 6A and 6B constituting the photoelectric conversion element of.

An attachment ring 43 formed by fixing an annular electromagnetic coil 42 is fixed to the rear peripheral surface of the movable body 2 so as to extend rearward,
Thus, the electromagnetic coil 42 is provided in the gear gap between the central protrusion of the first magnetic circuit member 24 and the third magnetic circuit member 26 so as to be displaceable in accordance with the displacement of the movable body 2. Magnetic circuit member 2 when exciting current flows
By magnetically coupling to the magnetic circuit composed of 4, 25 and 26, an electromagnetic force for suppressing the displacement of the movable body 2 is generated.

In this embodiment, spacers are provided on the front surfaces of the mounting members 38 and 40.
The wiring board 53 is attached via 51 and 52, and the wiring board 53 is provided with the vibration amount detection circuit section 7 having the configuration shown in FIG.

The vibration amount detection circuit unit 7 includes a light source drive circuit 56 that drives the light source 5.
From the semiconductor laser constituting the light source 5 via the code 57 from the semiconductor laser, and the irradiation light flux LA22 obtained by condensing the light source light LA21 by the condenser lens 2B is detected by the vibration amount detection circuit section. The light is focused on the photodiodes 6A and 6B that form a part of 7.

Here, the photodiodes 6A and 6B are connected, for example, with their cathodes back to back, and
By-pass resistors 61A and 61B are connected between the cathodes and anodes of 6A and 6B, respectively.

Thus, the photodetection current I _A obtained as a photoelectric conversion output from the one photodiode 6A whose anode is grounded is drawn to the photodetection circuit 59 through the bypass resistor 61B, and also from the other non-earthed photodiode 6B. can get.

The photodetection current I _B is drawn to the ground through the bypass resistor 61A, and as a result, the photodetection currents I _A and I _{B of the} photodiodes 6A and 6B are connected to the inverting input terminal of the operational amplifier circuit 62.
The detection current I _A −I _B representing the difference between the operational amplifier circuit 62 and the inverting input terminal of the operational amplifier circuit 62 is supplied as a photoelectric conversion output.
And is supplied to the differentiating circuit 63 as the deviation detection signal S1.

Thus, the deviation detection signal S1 is the displacement position of the irradiation light beam LA22 irradiated on the photodiodes 6A and 6B, and hence the case 22.
Changes in accordance with the vibration applied to the electromagnetic coil 42 and is supplied to the electromagnetic coil 42 and the output resistor 64 as the output current I _OUT after being subjected to the phase adjustment in the differentiating circuit 63.

Here, the electromagnetic coil 42 is magnetically coupled to the magnetic circuit members 24, 25, and 26, so that the electromagnetic current corresponding to the change in the output current I _OUT and the displacement amount of the movable body 2 is generated. A displacement servo loop that suppresses the displacement of 2 is formed.

At the same time, the output current I _OUT flows through the output resistor 64, and the dropped voltage is sent from the vibration amount detection circuit 7 as the vibration detection output S _OUT .

According to the above configuration, when the movable body 2 is displaced according to the vibration of the case 22, the displacement amount is the displacement of the irradiation position of the irradiation light beam LA22 with respect to the photodiodes 6A and 6B forming the photoelectric conversion element, and the light detection circuit. By suppressing the movable body 2 to a minute displacement through the servo loop which is detected at 59 and includes the electromagnetic coil 42, the movable body 2 is practically used.
Is a movable range with good linearity, that is, as described above with reference to FIG. 11, the total light amount change rate [dE / d (δx)] _SUM with respect to the photodiodes 6A and 6B is in a range with good linearity (ie, the displacement amount δx The displacement of the movable body 2 can be detected with high accuracy in the range of = 0).

Thus, according to the configuration of FIG. 14, the photodiodes 6A and 6B are connected back-to-back, and the photodiodes 6A and 6B are connected in parallel to the bypass resistors 61A and 61B. Photodiode 6A
And 6B can be obtained as a level detection that is large enough for practical use.

When forming a pair of photodiodes 6A and 6B on the same plane to receive the irradiation light flux LA22, if the back-to-back connection structure, it is possible to further simplify the manufacturing process of the photodiodes 6A and 6B, and the photodiode 6A and. Since only one terminal is required to be commonly used for 6B, the overall configuration can be simplified.

The resistance value of the photodiodes 6A and 6B is usually several [M
Ω], the resistance value is 61
By providing A and 61B, the photodiode 6A and
The photoelectric conversion current sent from 6B is used as a bypass resistor 61A and 61B.
Can be taken out efficiently via.

Further, in the configuration of FIG. 14, the light source drive circuit 56 drives the light source 5 which is a laser diode, and as shown in FIG. 15, the drive current I is changed to the boundary between the LED emission region EM _LED and the laser oscillation region EM _LSR. By suppressing the current to be smaller than the value I _TM , the laser diode LET is caused to emit light, which makes it possible to substantially emit the light source light LA21 of the light source 5 from the low-power point light source.

As a result, when irradiating the light beam LA12 on the photodiodes 6A and 6B, the diameter D of the light spot SPT of the light beam LA12 is irradiated.
Can be narrowed down to a diameter small enough for practical use,
As a result, the amount of displacement of the irradiation light beam LA22 on the photoelectric conversion unit 6 can be detected more highly accurately and stably.

When a semiconductor laser is used as the light source 5, when the semiconductor laser is driven to oscillate in the laser oscillation region EM _LSR , the coherency of the light source light LA11 and the irradiation light beam LA12 is improved, and thus the light source 5 and the windows of the photodiodes 6A and 6B are used. It is unavoidable that light fluctuations due to interference occur in the glass body of the portion and the condenser lens 2B.

Further, since the light source 5 is driven by the photocurrent, the amount of heat generated by the light source 5 is large, so that it is inevitable that the vibration measuring device 21 as a whole is affected by thermal expansion.

Regarding this point, as described above, the light source 5 is driven by LE having a low drive current.
By driving with the D emission region EM _LED , such a problem can be effectively avoided.

For example, when a semiconductor laser that oscillates an emitted light beam with a wavelength of 0.75 [μm] is used, it is sufficient to supply a driving current of about several [mA], which effectively produces noise that may occur due to heat generation and optical interference. Can be suppressed.

Further, according to the above configuration, by forming the condenser lens 2B by an aspherical lens, it is possible to efficiently converge an optical spot having a small diameter as the irradiation light beam LA12, and as a result, the detection accuracy of the displacement amount of the irradiation light beam LA12. Can be further increased.

If a general condenser lens is used instead of an aspherical lens, the shape and thickness will be large, so the aberration will be large and the weight balance will change (it has sensitivity in directions other than the vibration direction). However, the above-described embodiment can effectively solve this problem.

[4] Other Embodiments (1) The case of using a pair of photodiodes 6A and 6B connected back-to-back as photoelectric conversion elements of the photoelectric conversion section 6 has been described in the case of FIG. When applying a structure in which both the anode and cathode of 6A and 6B can be led to the outside, as shown in FIG. 16, the photoelectric conversion currents of the pair of photodiodes 6A and 6B are respectively placed in front. Amplifier circuits 71A and 71B
Is input to the operational amplifier circuits 71A1 and 71B1 that configure the above, and the output is supplied to the operational amplifier circuit 72A that configures the subtraction circuit 72,
The deviation detection signal S1 may be obtained at the output end of the operational amplifier circuit 72A.

According to the configuration of FIG. 16, the effect of simplifying the configuration in the case of FIG. 14 cannot be obtained, but in place of this, the precision of subtraction calculation can be further improved.

(2) In the same manner as described above with reference to FIG. 16, when the photoelectric conversion element of the photoelectric conversion unit 6 is configured so that the anode and the cathode can be derived from the photodiodes 6A and 6B, respectively, As shown in FIG. 17, the cathode and the anode of the photodiode 6B are connected in parallel to the anode and the cathode of the photodiode 6A to obtain a photoelectric conversion current from the connection end to obtain a preamplification circuit.
It is also possible to use the photodetector circuit 59 configured so as to be input to the operational amplifier circuit 75A that constitutes 75 and to output the output of the operational amplifier circuit 75A as the deviation detection signal S1.

In the configuration of FIG. 17, the photoelectric conversion currents obtained from the photodiodes 6A and 6B respectively flow into the preamplifier circuit 75A as currents in the opposite direction, so that the operational amplifier circuit 7A
A function equivalent to inputting a deviation signal indicating the difference between the detection outputs of the photodiodes 6A and 6B to 5A can be realized, and as a result, the deviation detection signal S1 is obtained, and the light detection circuit 59 is realized by a simple configuration. You can

Incidentally, the photodiodes 6A and 6B each have a high impedance (about several [MΩ]), whereas the input impedance of the operational amplifier circuit 75A can be considered to be practically 0 [Ω]. Even if 6B is directly connected to the operational amplifier circuit 75A, it is possible to effectively avoid the possibility that they will adversely affect each other in practical use, so that the photodiode can be directly connected to the preamplifier circuit 75 without providing any input circuit. Therefore, a simple configuration can be realized.

(3) In the above-mentioned embodiments, the aspherical lens is used as the condenser lens 2B, but instead of this, a rod lens may be applied.

Here, the rod lens has a cylindrical shape, an optical axis of which is the central axis, and an optical index distribution in which the refractive index increases toward the center in a cross section orthogonal to the optical axis. Have a configuration.

According to this structure, when the irradiation light beam LA12 is converged to a sufficiently small optical spot diameter for practical use, it is possible to obtain a practically sufficiently large converging effect by the refraction action occurring along the sufficiently long optical axis. Therefore, the diameter of the rod lens can be selected to be a sufficiently small value.

Thus, the thickness of the movable body 2 in the vibration direction can be made sufficiently thin for practical use, and thus the balance and sensitivity characteristics of the movable body 2 can be further improved.

(4) In the configuration of FIG. 12 and FIG.
Although the electromagnetic coil 42 is provided on the movable body 2 side as the displacement servo means for suppressing the displacement of the above, the displacement servo means is not limited to this. For example, an electromagnetic force generating means may be provided on the fixed part side. The electromagnetic force may be used to obtain a suppressing force that suppresses the displacement of the body 2.

(5) In the case of the configuration shown in FIG. 14, the case where the pair of photodiodes 6A and 6B are connected to each other with their cathodes back to back has been described. Alternatively, however, the anodes may be connected to each other back to back. The same effect as the above case can be obtained.

(6) In the case of the configuration of FIG. 17, a pair of photodiodes
When connecting 6A and 6B in parallel, the cathode of one photodiode 6A was connected to the anode of the other photodiode 6B.On the contrary, the anode of one photodiode 6A was connected to the other photodiode 6A. Even if it is connected to the cathode of 6B, the same effect as the above case can be obtained.

〔The invention's effect〕

As described above, according to the present invention, the light spot of the irradiation light flux converged on the photoelectric conversion element is displaced through the condenser lens held by the movable body which is displaced by the vibration amount to be measured. By virtue of the configuration, it is possible to easily realize a vibration measuring device capable of measuring the vibration amount with higher performance with a simple structure as a whole in practical use.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a principle structure of an optical detecting portion of a vibration measuring device according to the present invention, and FIGS. 2 and 3 are schematic optical paths for explaining the optical detecting operation. 4 to 11 are schematic diagrams and characteristic curve diagrams for explaining the optimum conditions between the irradiation light flux converged on the photoelectric conversion portion and the photodiode, and FIG. 12 is the vibration of the present invention. A cross-sectional view showing an embodiment of the measuring device, FIG. 13 is XIII- of FIG.
FIG. 14 is a block diagram showing the vibration amount detection circuit section, FIG. 15 is a characteristic curve diagram used for explaining the light emission conditions of the light source, and FIGS. 16 and 17 are light detection lines. FIG. 18 is a connection diagram showing another embodiment of the circuit, and FIG. 18 to FIG. 20 are a perspective view, a cross-sectional view, and an optical path schematic diagram showing a conventional configuration. 1 ... Optical detector, 2 ... Movable body, 2A ... Lens barrel, 2B ...
… Condenser lens, 5 …… Light source, 6 …… Photoelectric converter, 6A, 6B
…… Photodiode, 7 …… Vibration amount detection circuit, 21…
… Vibration measuring device, 22 …… Case, 24-26 …… Magnetic circuit part, 42 …… Electromagnetic coil, 56 …… Light source drive circuit, 59 …… Light detection circuit ,.

Claims (5)

[Claims] 1. A second device which is adapted to be displaced in a first direction in response to a vibration amount to be measured and which is orthogonal to the first direction.
And a movable body that holds a condenser lens having an optical axis in the first direction, and a movable body that is disposed so as to extend in a third direction orthogonal to the first and second directions. A support body that elastically supports the condenser lens so that it can be displaced, a light source disposed on the optical axis of the condenser lens so as to face the condenser lens, and a pair of photoelectric conversion elements. The irradiation light flux obtained by focusing the light source light emitted from the condenser lens by the condenser lens is received by the pair of photoelectric conversion elements, and the irradiation light flux changes the irradiation position according to the displacement of the movable body. When the displacement is made, the pair of photoelectric conversion elements transmits a photodetection signal corresponding to the displacement amount, and a vibration amount measurement output is transmitted based on the deviation of the photodetection signal transmitted from the photoelectric conversion unit. Of the vibration amount detection circuit and the light detection signal Comprising a displacement servo means for generating a displacement restraining force consisting of an electromagnetic force to the movable body based on the difference, with respect to the spacing L between the light-receiving surface of the pair of photoelectric conversion elements,
A vibration measuring device, characterized in that the diameter D of the irradiation luminous flux is selected to a value that satisfies a relationship of approximately L = 0.8D. 2. The vibration measuring device according to claim 1, wherein the condenser lens is an aspherical lens. 3. The condensing lens is a rod lens having a cylindrical shape and having a refractive index distribution toward the center in a cross section orthogonal to the central axis of the cylindrical shape. The vibration measuring device according to claim 1, which is characterized. 4. The first and second photoelectric conversion elements are composed of photodiodes in which cathodes or anodes are connected back-to-back with each other, and the vibration amount detection circuit section includes the first and second photoelectric conversion elements. A difference in photoelectric conversion output obtained from the first and second photoelectric conversion elements through the first and second bypass resistors by connecting the first and second bypass resistors in parallel to the device, respectively. An output is obtained, and the difference output is sent as a deviation detection signal through an operational amplifier circuit. Claims 1, 2, or 3
The vibration measuring device according to the item. 5. The first and second photoelectric conversion elements are each formed of a photodiode, and the vibration amount detection circuit section uses the anode and cathode of the first photoelectric conversion element as the second photoelectric conversion element. Of the photoelectric conversion outputs obtained from the first and second photoelectric conversion elements through the connection point by connecting the cathode and the anode of the parallel connection to each other, and the difference output is detected through the operational amplifier circuit. The vibration measuring device according to claim 1, 2, or 3, which is transmitted as a signal.