JP2007178298A - Oscillatory type inertial force detection sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oscillation type inertial force detection sensor reduced in electric power consumption. <P>SOLUTION: The oscillation type inertial force detection sensor is provided with: an oscillator 4; a driving circuit 6 for oscillating the oscillator 4; a detection circuit 8 for detecting distortions which occur in the oscillator 4 owing to the Coriolis force (inertial force); and an electric power supply circuit 10 for supply electric power for the driving circuit 6 and the detection circuit 8. The oscillation type inertial force detection sensor is provided with: a sleep function to shift to such a power-saving state as to supply electric power for the driving circuit 6 but not for the detection circuit 8 when not receiving the Coriolis force; and a return circuit 12 for returning from the power saving state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vibration type inertial force detection sensor used in various electronic devices.

  Hereinafter, a conventional vibration type inertial force detection sensor will be described.

  An example of the vibration type inertial force detection sensor is an angular velocity sensor. The angular velocity sensor includes a vibrator, a drive circuit for vibrating the vibrator, and distortion generated in the vibrator due to Coriolis force (inertial force). And a power supply circuit for supplying power to the drive circuit and the detection circuit.

  There are various types of vibrators such as a tuning fork shape, H shape, T shape, and sound piece shape. By vibrating this vibrator, the distortion of the vibrator accompanying the generation of Coriolis force is electrically affected. It detects and calculates angular velocity.

  Such an angular velocity sensor is mounted, for example, as a component constituting a camera shake prevention function of a digital camera.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
JP 2002-243451 A

  Generally, since a digital camera is operated by driving a battery, the usable time is shortened if the power consumption of the battery is increased. Therefore, in order to save battery power consumption and use it for a long time, when not in use, the power supply to the main function is set to the minimum and the power supply to other additional functions is cut off. Has been.

  However, the angular velocity sensor constituting the camera shake prevention function is always supplied with electric power, which has a problem that it obstructs power saving of battery power consumption.

  The present invention solves the above-described problems, and an object thereof is to provide a vibration type inertial force detection sensor with reduced power consumption.

  In order to achieve the above object, in particular, the present invention is provided with a sleep function for shifting to a power saving state in which power is supplied to the drive circuit but power is not supplied to the detection circuit.

  With the above configuration, power is not supplied to the detection circuit for detecting distortion generated in the vibrator due to inertial force, so that power consumption can be reduced.

  In particular, power is not supplied to the detection circuit, but power is supplied to the drive circuit. Therefore, when returning from the power saving state, the return time for functioning as the vibration type inertial force detection sensor can be shortened. This is because when the power to the drive circuit for vibrating the vibrator is cut off and power is supplied again, the vibrator that has stopped vibrating due to the power cutoff is supplied with power again and the vibrator vibrates. Even so, it takes time for the vibration of the vibrator to become stable. Therefore, accurate detection cannot be performed until the vibration of the vibrator becomes stable. However, if the power to the drive circuit for vibrating the vibrator is supplied without being cut off, the vibration of the vibrator is always in a stable state, and time is not required for the return time from the power saving state.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  An angular velocity sensor is an example of the vibration type inertial force sensor according to an embodiment of the present invention.

  FIG. 1 is a block diagram of an angular velocity sensor according to an embodiment of the present invention, and FIG. 2 is a plan view of a vibrator of the angular velocity sensor.

  1 and 2, the angular velocity sensor 2 detects a transducer 4, a drive circuit 6 for vibrating the transducer 4, and distortion generated in the transducer 4 due to Coriolis force (inertial force). And a power supply circuit 10 for supplying power to the drive circuit 6 and the detection circuit 8.

  In addition, a sleep function is provided for shifting to a power saving state in which power is supplied to the drive circuit 6 but power is not supplied to the detection circuit 8 based on a power saving signal for shifting to the power saving state. This power saving signal is generated when the Coriolis force is not applied.

  Further, a return circuit 12 that returns from the power saving state after being shifted to the power saving state by the sleep function is provided.

  The vibrator 4 includes a drive electrode 16 and a detection electrode 18 having a multilayer structure formed by sandwiching a piezoelectric thin film made of PZT with an electrode made of a metal conductor such as Ag or Au, on a tuning fork-shaped silicon substrate 14. Formed. Although not shown, the silicon substrate 14 may have an H shape, a T shape, a tuning fork shape, or the like.

  The drive circuit 6 is a circuit that controls the drive voltage applied to the drive electrode 16 so that the vibration of the vibrator 4 vibrates with a constant amplitude. The drive circuit 6 includes an AGC, an amplifier, and the like, and the detection circuit 8 generates Coriolis force. This is a circuit for processing a detection signal that is electrically output from the detection electrode 18 due to the distortion of the accompanying vibrator 4, and includes an operation circuit, an integration circuit, an IC, and the like.

  Such an angular velocity sensor 2 is mounted, for example, as a component constituting a camera shake prevention function of the digital camera 20 as shown in FIG. Further, since the digital camera 20 is generally driven by the battery 22, the usable time is shortened if the power consumption of the battery 22 is increased. Therefore, in order to save power consumption of the battery 22 so that it can be used for a long time, the power supply to the main function is set to the minimum when not in use and the power supply to other additional functions is cut off. It has been adopted.

  In the angular velocity sensor 2 having the above-described configuration, when no Coriolis force is received, power is not supplied to the detection circuit 8 for detecting distortion generated in the vibrator 4 due to the Coriolis force, so that power consumption can be reduced. If this angular velocity sensor 2 is used in the digital camera 20, the power consumption of the battery 22 of the digital camera 20 can also be saved. Further, the time until the power is not supplied to the detection circuit 8 may be set immediately after the Coriolis force is not received or after a certain time has passed since the Coriolis force is not received, and may be set according to the specification.

  In particular, when no Coriolis force is received, no power is supplied to the detection circuit 8, but power is supplied to the drive circuit 6. Can be fast. This is because when the electric power to the drive circuit 6 for vibrating the vibrator 4 is cut off and the electric power is supplied again, the vibrator 4 whose vibration is stopped by the interruption of the electric power is again supplied with electric power and vibrated. Even if the child 4 vibrates, it takes time until the vibration of the vibrator 4 becomes stable. Therefore, accurate detection cannot be performed until the vibration of the vibrator 4 becomes stable. However, since the power to the drive circuit 6 for vibrating the vibrator 4 is supplied without being cut off, the vibration of the vibrator 4 is always in a stable state, and no time is required for the return time from the power saving state. .

  Furthermore, since the angular velocity sensor 2 includes the return circuit 12 that returns from the power saving state, the angular velocity sensor 2 can smoothly return from the power saving state. When the external signal 24 that prompts the return is input to the return circuit 12, power may be supplied to the detection circuit 8 to cancel the sleep function. For example, the external signal 24 for prompting the return may be transmitted from the digital camera 20 on which the angular velocity sensor 2 is mounted, and various buttons of the digital camera 20 may be used as a transmission switch for the external signal 24.

  In the vibration type inertial force sensor according to the above-described embodiment, when no Coriolis force (inertial force) is received, a power saving signal is generated and power is supplied to the drive circuit 6, but the detection circuit 8 is supplied with power. Although a sleep function for shifting to a power saving state in which no power is supplied is provided, the power saving signal may be intentionally generated to shift to a power saving state. For example, when mounted on the digital camera 20, various buttons and the like of the digital camera 20 may be used as a power saving signal transmission switch.

  Furthermore, the present invention can be applied not only to the angular velocity sensor 2 but also to a mode in which an inertial force is detected based on the vibration of the vibrator 4 such as an acceleration sensor having the vibrator 4.

  As described above, the vibration type inertial force sensor according to the present invention can reduce power consumption, and thus is useful for various electronic devices.

The block diagram of the angular velocity sensor in one embodiment of this invention Plan view of transducer of same angular velocity sensor Perspective view of a digital camera equipped with the same angular velocity sensor

Explanation of symbols

2 angular velocity sensor 4 vibrator 6 drive circuit 8 detection circuit 10 power supply circuit 12 return circuit 14 silicon substrate 16 drive electrode 18 detection electrode 20 digital camera 22 battery 24 external signal

Claims (4)

A vibrator, a drive circuit for vibrating the vibrator, a detection circuit for detecting distortion generated in the vibrator due to inertial force, and supplying power to the drive circuit and the detection circuit A vibration type inertial force detection sensor provided with a sleep function for shifting to a power saving state in which power is supplied to the drive circuit but power is not supplied to the detection circuit. The vibration type inertial force detection sensor according to claim 1, further comprising a return circuit for returning from the power saving state. The vibration type inertial force detection sensor according to claim 1, wherein the vibration type inertial force detection sensor is shifted to the power saving state based on a power saving signal for shifting to the power saving state. The vibration type inertial force detection sensor according to claim 3, wherein the power saving signal is generated when the inertial force is not received.

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