JPH10339739A - Inertia sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a sensor and to improve detection accuracy by arranging a signal-generating member in parallel with the plane of a weight part and accommodating the length of the signal-generating member being extended radially within the range of the length in the plane direction of the weight part. SOLUTION: A beam 12d that is a strain-voltage conversion member for generating a resistance change due to, for example, a semiconductor strain gauge for generating a signal according to acceleration and angular velocity being applied to an inertia disk 11 is provided. A signal being generated by a pair of beams 12d is amplified by each amplifier 13 and is subjected to arithmetic processing by an addition circuit 14 and a differential circuit 15. Since the beams 12d are extended from an area near the center of gravity of the inertial disk 11, the space of the inertia disk 11 can be used to the limit for the size of the entire inertia sensor, so that the partial inertial force can be fully utilized. Also, the size needs to be only the length of the diameter of the inertia disk 11, thus miniaturizing a sensor. Further, the beams 12d are extended from an area near the center of gravity of the inertia disk 11 irrespective of the shape thereof, thus extending the length of the beams 12d and improving sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inertial sensor for detecting acceleration and angular acceleration, and more particularly to an inertial sensor mounted on an optical device and suitable for detecting a hand vibration applied to the optical device. .

[0002]

2. Description of the Related Art Conventionally, an inertial sensor for detecting acceleration and angular acceleration has a weight 41, a frame 42, and a beam 43 supporting the weight 41 from the frame 42, as shown in FIG.
Are formed from an integral Si (silicon) single crystal substrate. A piezoresistor 44 is formed on the beam 43 supporting the weight 41.

FIG. 9B is a cross-sectional view of FIG. 9A. When an angular acceleration β is applied in this state, the weight 41 is attached to the frame 42 by inertia as shown in FIG. 9C. It rotates relatively to it. Thereby, the beam 43 bends, and the deflection is detected by the plurality of piezoresistors 44, and the direction and magnitude of the angular acceleration can be obtained by calculating by a control circuit (not shown).

When a linear acceleration α is applied, as shown in FIG. 9D, the weight 41 moves relative to the frame 42, and the amount of movement is detected by the piezoresistor 44. Thus, the direction and amount of the linear acceleration α can be detected.

[0005]

The sensitivity of the inertial sensor as described above is determined by the sensitivity of the piezoresistor 44 and the relationship between the rigidity of the beam 43 and the weight of the weight 41 (natural frequency). That is, even if the sensitivity of the piezoresistor 44 is the same, the beam 4
The sensitivity of the inertial sensor can be improved by weakening the rigidity of the inertial sensor 3 or increasing the weight of the weight 41.

Consider a case in which such an inertial sensor is mounted on an optical device such as a camera to detect a camera shake angular acceleration and an acceleration.

The camera shake mentioned here is, for example, 0.1 mg.
(1 / 10,000 of gravity), which is extremely weak. To accurately detect such a shake, it is necessary to increase the sensitivity of the inertial sensor.

However, when the inertial sensor is mounted on consumer equipment such as a camera, the size of the inertial sensor must be reduced, and the weight cannot be increased to improve the sensitivity. In addition, if the rigidity of the beam is reduced, reliability cannot be established.

For the reasons described above, it is difficult to make the conventional inertial sensor compact and highly accurate, and it has not been possible to mount the conventional inertial sensor on consumer equipment such as a camera.

(Object of the Invention) A first object of the present invention is to provide an inertial sensor which is small in size and capable of detecting highly accurate acceleration and angular acceleration.

A second object of the present invention is to provide an inertial sensor that can be manufactured at low cost.

A third object of the present invention is to provide an inertial sensor which can improve the detection accuracy, can be manufactured at low cost, and can eliminate the possibility of damaging the supporting means due to the vibrations when carrying. To provide.

[0013]

In order to achieve the first object, according to the present invention, there is provided an inertial sensor having a weight portion and a support means for supporting the weight portion. The support means may be an inertial sensor having a signal generating member extending radially from the vicinity of the center of gravity of the weight portion and generating a signal corresponding to acceleration or angular acceleration applied to the weight portion.

In the above structure, for example, the weight portion is formed in a flat plate shape, and the signal generating member is parallel to the plane of the weight portion and extends radially from near the center of gravity in a direction perpendicular to the plane of the weight portion. Shape. In this manner, the signal generating member is parallel to the plane of the weight, and is arranged in a direction perpendicular to the plane of the weight,
The length of the radially extending signal generating member is set within the range of the length of the weight in the planar direction. Further, the signal generating member may be formed to extend radially from the vicinity of the center of gravity in a direction perpendicular to the plane of the weight portion, and the length may be the same as that of the signal generation member according to the acceleration or angular acceleration applied to the weight portion. It is long enough to generate a very large signal.

Further, in order to achieve the second object,
According to a fifth aspect of the present invention, there is provided an inertial sensor having a weight portion and a support means for supporting the weight portion, wherein the support means generates a signal corresponding to acceleration or angular acceleration applied to the weight portion. And an inertial sensor formed of a resin member integrally molded with the signal generating member.

As described above, the support means is constituted by a resin member in which the signal generating member is integrally formed.

Similarly, in order to achieve the second object,
According to a sixth aspect of the present invention, there is provided an inertial sensor having a weight portion and a support means for supporting the weight portion, wherein the support means generates a signal corresponding to an acceleration or an angular acceleration applied to the weight portion. And an inertial sensor formed of a resin member integrally molded with the elastic member.

As described above, the support means is constituted by a resin member integrally formed with an elastic member having a signal generating member.

In order to achieve the third object,
According to a ninth and tenth aspect of the present invention, in the inertial sensor having a weight portion and a support means for supporting the weight portion, the support means generates a signal corresponding to an acceleration or an angular acceleration applied to the weight portion. An elastic member provided with a signal generating member, and a vibration absorbing member for absorbing unnecessary vibration of the elastic member, and each of these members is an inertial sensor formed of a resin member integrally molded. is there.

As described above, the supporting means is constituted by an elastic member provided with a signal generating member and a resin member integrally formed with a vibration absorbing member integrally formed so as to sandwich the elastic member. The member suppresses a large vibration at the time of carrying or the like at the natural resonance frequency determined by the elastic constant of the elastic member and the mass of the weight.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a perspective view of an inertial sensor according to a first embodiment of the present invention. Numeral 11 denotes an inertial disk (weight portion) formed of a substance having a high specific gravity such as copper. Reference numeral 12 denotes a support means, which is a support frame 12a for supporting the inertial disk 11.
And a beam 1 that is a member (strain voltage conversion member) that generates a signal corresponding to the acceleration or angular acceleration applied to the disk 11 and that generates a resistance change due to strain, such as a semiconductor strain gauge.
2d and a receiving portion 12b provided with a shaft 12c for press-fitting the inertial disk 11 are integrally formed of a resin member (the supporting frame 12a and the receiving portion 12b are resin members). Twin beams 12
The signal (distortion voltage) generated at d is amplified by the amplifier 13 and is processed by the adder circuit 14 and the differential circuit 15. The components from the amplifier 13 to the differential circuit 15 correspond to a detecting means for detecting the input acceleration and the input angular acceleration.

FIG. 2 is a diagram of the inertial sensor of FIG. 1 viewed from the axial direction, and shows a case where a linear acceleration is applied to the inertial sensor in the direction of arrow 15.

In this case, since each beam 12d bends (distorts) in the same direction, the added value of each output (addition circuit 14)
) Changes to indicate linear acceleration, but the differential values (outputs of the differential circuit 15) cancel each other out and do not change.

FIG. 3 is a view of the inertial sensor of FIG. 1 viewed from the axial direction, similarly to FIG. 2, and shows a case where a rotational acceleration (angular acceleration) is applied to the inertial sensor in the direction of arrow 16.

In this case, since each beam 12d bends in the opposite direction, the added value of each beam does not change, but the differential value changes.

That is, the linear acceleration can be known by the sum of the outputs of the beams 12d, and the angular acceleration can be known by the differential value.

FIG. 4 is a block diagram showing the circuit configuration of the inertial sensor having the configuration shown in FIG. 1. The beam 12d, which is a resistor, forms a bridge with a resistor 17 having the same value. , 2V _PP ).

When the resistance value of the beam 12d changes due to the bending of the beam 12d, the voltage between the bridges changes and the voltage is amplified by the amplifier 13. Since this signal is modulated on 20 KHz, the band only by cutting the rest of the noise in the band pass filter 19 which transmits, demodulated by a reference signal oscillator 18 by detector 110, the 20 kHz _Z components in the low-pass filter 111 Smoothing. After that, the addition circuit 14,
The signal is input to the differential circuit 15 to obtain a linear acceleration and an angular acceleration.

Since the AC amplification is performed as described above, the influence of noise (including low frequency drift) in the amplifier circuit is eliminated.

The feature of the first embodiment is that the beam 12d extends from near the center of gravity (center) of the inertial disk 11. As a result, with respect to the size of the entire inertial sensor,
The space of the inertial disk 11 can be used up to the last minute, and the inertia force can be greatly utilized accordingly. In addition, since the size of the inertial disk 11 is only the length of the diameter of the inertial disk 11, the size of the inertial disk 11 can be extremely reduced as compared with the related art. Furthermore, while having such a shape, the beam 1 is located near the center of gravity (center) of the inertial disk 11.
Since 2d is extended, the length of the beam 12d can be made sufficiently long, and the amount of bending can be increased.
Moreover, since the length of the semiconductor strain gauge can be increased, the sensitivity can be increased. Therefore, the sensitivity of the inertial sensor can be greatly improved.

Next, since the semiconductor strain gauge forming the beam 12d is integrally formed with the resin support frame 12a and the receiving portion 12b, no work for mounting is required, so that the working cost can be reduced and the parts can be reduced. Reliability has also been improved.

Although the beam 12d has been described using a semiconductor strain gauge, the invention is not limited to this. Needless to say, a resistance wire strain gauge, a piezoelectric element or the like may be used.

(Second Embodiment) FIG. 5 shows an inertial sensor according to a second embodiment of the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The difference from FIG. 1 is that the beam 21 is not a semiconductor strain gauge but a plate spring such as beryllium-copper or the like, and the semiconductor strain gauges 12e (12e ₁ to 12e ₁₎
2e ₄ ) is attached. The beam 21 made of a leaf spring is formed integrally with the receiving portion 12b and the support frame 12a in a state where the semiconductor strain gauge is attached in advance. Therefore,
The inertial sensor can be manufactured at low cost.

Since the semiconductor strain gauge 12e is attached to the front and back surfaces of the beam 21 made of a leaf spring, a circuit for detecting a resistance change (voltage change) caused by bending has a bridge configuration as shown in FIG.

When the beam 21 bends, the semiconductor strain gauge 12e on one of the front and back sides expands, and the other contracts, so that the output can be doubled by adopting the configuration shown in FIG.

With such a configuration, the semiconductor strain gauge 1
2e can be made thinner, so that the cost can be reduced. In addition, since the inertial disk is supported by the beam 21 made of a leaf spring, the durability can be improved, and the detection sensitivity can be further increased.

(Third Embodiment) FIG. 7 shows an inertial sensor according to a second embodiment of the present invention. The same parts as those in FIGS. 1 and 5 are denoted by the same reference numerals, and description thereof will be omitted.

The difference from FIG. 5 is that the sides of the leaf spring 21 are wrapped around the resin frame 12f of the support frame 12a.

The beam 21 composed of a leaf spring has a natural frequency (resonance point) obtained from its spring constant and the mass of the inertial disk 11.
Shows large amplitude vibration. Therefore, when an acceleration near this frequency is applied, the detection accuracy is significantly reduced. In the third embodiment, in order to solve this problem, the side of the beam 21 made of a leaf spring is
The structure is such that large-amplitude vibration at the resonance point is suppressed by e. (The resin frame 12e is used as a vibration absorbing member.) As a result, the accuracy of detecting acceleration at a frequency near the natural frequency can be improved, and the inertia disk 11 can be used for vibration (near the natural frequency) when carrying. Vibrates greatly, thereby preventing the beam 21 from being deformed or damaged.

The circuit configuration of this inertial sensor is the same as that of FIG. 5, but if only the angular acceleration needs to be detected, for example, four semiconductor strain gauges 12e ₁ and 12e as shown in FIG.
_{When the} bridges ₂ , 12 e ₃ and 12 e ₄ are formed in a bridge configuration, only the deflection of the beam due to angular acceleration can be detected, and the circuit can be greatly simplified.

Although the correspondence between each configuration of the present invention and each configuration of the embodiment is as described above, the present invention is not limited to the configuration of the embodiment and is described in the claims. It goes without saying that any configuration may be used as long as the function or the function of the embodiment can be achieved.

(Modification) In the above embodiment,
The weight portion is exemplified by a flat plate shape, but is not limited thereto.For example, two triangular pyramid shapes are provided, and their apex portions are opposed to each other, and these apex portions are May be supported by supporting means. In this case, since the position of the center of gravity of the weight portion is located at a position where the respective apex portions face each other, by extending a beam member such as a semiconductor strain gauge radially from this position, the object of the present invention is to provide an inertial sensor. And the detection accuracy of acceleration and angular acceleration can be improved.

[0045]

As described above, according to the present invention,
The signal generating member is parallel to the plane of the flat weight,
And, by arranging in a direction perpendicular to the plane of the weight portion, the length of the signal generating member extending radially, so as to fit within the range of the length of the weight portion in the plane direction, The signal generating member is shaped to extend radially from the vicinity of the center of gravity in the direction perpendicular to the plane of the weight, and has a relatively large size corresponding to the acceleration or angular acceleration applied to the weight while having the above length. Since the length is set to be long enough to generate a signal, it is possible to provide an inertial sensor which is small and capable of detecting highly accurate acceleration and angular acceleration.

Further, according to the present invention, since the supporting means is constituted by a resin member in which the signal generating member is integrally formed, an inertial sensor which can be manufactured at low cost can be provided.

Further, according to the present invention, since the supporting means is constituted by a resin member in which an elastic member having a signal generating member is integrally formed, an inertial sensor which can be manufactured at low cost can be provided. Things.

According to the present invention, the supporting means is constituted by an elastic member having a signal generating member, and a resin member integrally molded with a vibration absorbing member integrally molded so as to sandwich the elastic member. Because the vibration absorbing member suppresses large vibrations at the time of carrying, etc., at the natural resonance frequency determined by the elastic constant of the elastic member and the mass of the weight portion, the detection accuracy is improved and the device is manufactured at low cost. It is possible to provide an inertial sensor that can eliminate the possibility of damaging the support means due to vibrations when the portable device is carried.

[Brief description of the drawings]

FIG. 1 is a perspective view of an inertial sensor according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state when a linear acceleration in an arrow direction is applied to the inertial sensor of FIG. 1 as viewed from the axial direction thereof.

FIG. 3 is a diagram showing a state when a rotational angular velocity in an arrow direction is applied to the inertial sensor of FIG. 1 as viewed from the axial direction thereof.

FIG. 4 is a block diagram showing a circuit configuration of the inertial sensor of FIG.

FIG. 5 is a perspective view of an inertial sensor according to a second embodiment of the present invention.

FIG. 6 is a block diagram showing a circuit configuration of the inertial sensor of FIG.

FIG. 7 is a perspective view of an inertial sensor according to a third embodiment of the present invention.

FIG. 8 is a block diagram illustrating a circuit configuration of the inertial sensor of FIG. 7;

FIG. 9 is a diagram for explaining a structure of a conventional inertial sensor and a case of detecting acceleration and angular velocity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Inertial disk 12 Support means 12a Support frame 12d Beam made of a semiconductor strain gauge 12e Semiconductor strain gauge 14 Amplifying circuit 15 Differential circuit 21 Beam made of a leaf spring

Claims (10)

[Claims] 1. An inertial sensor having a weight part and a support means for supporting the weight part, wherein the support means extends radially from near the center of gravity of the weight part, and acceleration or angular acceleration applied to the weight part An inertial sensor comprising a signal generating member for generating a signal according to the following. 2. The signal generating member radially extends from the vicinity of the center of gravity of the weight portion, and generates a distortion by applying acceleration or angular acceleration to the weight portion, and generates a voltage signal according to the amount of the distortion. The inertial sensor according to claim 1, wherein the inertial sensor is a member. 3. A detection means for detecting the input acceleration and the input angular acceleration from a distortion voltage conversion signal generated at each portion of the signal generating member extending radially from near the center of gravity of the weight portion. 3. The inertial sensor according to claim 2, wherein: 4. The weight portion has a flat plate shape, and the signal generating member is parallel to a plane of the weight portion, and
The inertial sensor according to claim 1, wherein the inertial sensor has a shape extending radially from near a center of gravity in a direction perpendicular to a plane of the weight portion. 5. An inertial sensor having a weight portion and a support means for supporting the weight portion, wherein the support means has a signal generating member for generating a signal corresponding to an acceleration or an angular acceleration applied to the weight portion. An inertial sensor characterized in that the signal generating member is formed of a resin member integrally molded. 6. An inertial sensor having a weight portion and support means for supporting the weight portion, wherein the support means includes a signal generating member for generating a signal corresponding to acceleration or angular acceleration applied to the weight portion. An inertial sensor, comprising an elastic member formed as described above, and a resin member formed by integrally molding the elastic member. 7. The apparatus according to claim 1, wherein said signal generating member is a resistance strain gauge or a semiconductor strain gauge.
7. The inertial sensor according to 5 or 6. 8. The inertial sensor according to claim 6, wherein the elastic member is a leaf spring. 9. An inertial sensor having a weight portion and support means for supporting the weight portion, wherein the support means includes a signal generating member for generating a signal corresponding to acceleration or angular acceleration applied to the weight portion. An inertial sensor, comprising: an elastic member formed as described above; and a vibration absorbing member for absorbing unnecessary vibration of the elastic member. 10. The inertial sensor according to claim 9, wherein said vibration absorbing member is integrally formed so as to sandwich an elastic member provided with said signal generating member.