JPH08297028A - Angular velocity detector - Google Patents

Abstract

PURPOSE: To improve the detecting accuracy in a simple constitution by holding a differential signal of a differential circuit outputting a difference of output voltages of a pair of piezoelectric elements for every predetermined integral cycle of an oscillation cycle of an oscillation circuit. CONSTITUTION: A differential signal 61 from a differential circuit 6 which outputs a difference of output signals 43 and 44 converted from voltages by piezoelectric elements 41, 42 is held by a holding circuit 10 and output as a holding voltage 11. The differential signal 61 is held with a rise timing of an oscillation signal 51 of an oscillation circuit 5 and held once every cycle afterwards. Accordingly, the holding voltage 11 can be obtained approximately at a peak point of the differential signal. Then, the holding voltage 11 is smoothed by an LPF 8, thereby an angular velocity signal 81b is obtained. If an oscillation frequency of the oscillation circuit 5 is high to a certain extent to a jitter frequency, a step difference of signals appearing in the output of the holding circuit 10, namely, the difference of output values resulting from samplings becomes small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity detecting device using a vibrating gyro, which is mounted on an image pickup device such as a video camera or an automobile.

[0002]

2. Description of the Related Art An example of a conventional angular velocity detecting device will be described with reference to FIGS.

FIG. 5 is a diagram showing a configuration of a vibration gyro in a conventional angular velocity detecting device, FIG. 6 is a block diagram showing a configuration of the angular velocity detecting device, and FIG. 7 is a diagram for explaining a signal flow. is there. In addition, in FIG. 5 and FIG. 6, the same reference numerals are given to the same elements.

As shown in FIG. 5, a conventional vibrating gyro 1 has, for example, a regular hexagonal prism structure, and electric vibrations are converted into mechanical vibrations on a pair of surfaces facing each other on a regular hexagonal prism vibrating body 2. The first oscillator 31 and the second oscillator 32 are arranged. Both vibrators 31 and 32 are composed of piezoelectric elements or the like, and mechanical vibration is generated by applying a voltage that reverses the polarity from the outside.

Further, a pair of piezoelectric elements 41, 42 located on the surfaces 23, 24 which are not parallel to the vibration direction a of the vibrating body 2 and arranged substantially symmetrically with respect to the central axis b of the vibrating body 2,
Convert mechanical vibrations into electricity.

In FIG. 6, an oscillation circuit 5 for generating electrical vibration outputs an oscillation signal at a specific cycle, and the output is supplied to a vibrator 31 and directed in the direction indicated by a in FIGS. 5 and 6. Converted to mechanical vibration (flexing motion).

Next, this mechanical vibration is transmitted to the piezoelectric elements 41, 4
After being converted into electric vibration by 2, the difference circuit 6 outputs the difference between the outputs of the piezoelectric element 41 and the piezoelectric element 42. The blanking circuit 7 detects the output signal (difference signal) of the difference circuit 6, and the low-pass filter 8 smoothes the detected signal and shapes the waveform to output it as an angular velocity signal. The delay circuit 9 delays the oscillation signal of the oscillation circuit 5 by a predetermined amount and outputs it to the blanking circuit 7 as a blanking signal.

Next, the operation of each element will be described.

First, when the vibrating gyro 1 is stationary,
Since the vibration amounts of the surface 23 and the surface 24 of the vibrating body 2 are equal, the electric outputs of the piezoelectric element 41 and the piezoelectric element 42 are equal,
The output of the difference circuit 6 becomes zero.

Next, when the vibrating gyro 1 is moved in the rotational direction around an arbitrary axis substantially parallel to the central axis b of the vibrating body 2 shown in FIG. 5, the surfaces 23, 24 of the vibrating body 2 are given.
, The vibration amount is unbalanced due to the Coriolis force, and a difference occurs in the electric output between the piezoelectric element 41 and the piezoelectric element 42.

When the difference circuit 6 outputs the difference between the electric outputs of the two, an output having a different phase with respect to the oscillation circuit 5 is obtained depending on the rotating direction of the vibrating body 2, and an output level proportional to the rotation speed is obtained. It is obtained as a differential signal.

The differential signal is detected by the detection circuit of the blanking circuit 7, the waveform is shaped by the smoothing circuit of the low pass filter 8 and output as an angular velocity signal.

The signal flow will now be described in more detail with reference to FIG.

Piezoelectric element outputs 43 and 44 obtained from the piezoelectric elements 41 and 42 are input to the differential circuit 6 to obtain a differential signal 61. In order to explain the process for obtaining the angular velocity signal 81 in FIG. 4, it is assumed that the vibrating gyro 1 is rotated and the outputs of the piezoelectric elements 41 and 42 are unbalanced.

The oscillation signal 51 output from the oscillation circuit 5 is input to the delay circuit 9 and delayed by a predetermined amount and output as a blanking signal 91. The positive period 91a of the blanking signal 91 is used, and the difference signal 61 is used only during this period.
Is replaced with a reference voltage (for example, a central voltage) to obtain a detection output signal 71. This detection output signal 71
Waveform is shaped by the low-pass filter 8 and the angular velocity signal 81
Output as a. Then, the angular velocity is obtained based on the angular velocity signal 81a.

The blanking timing can be detected by blanking about half cycle including the positive or negative peak of the differential output signal 61 of the differential circuit 6, and the delay amount by the delay circuit 9 can be detected. Is also set in consideration of this condition.

[0017]

However, in the above-described conventional angular velocity detecting device, since the detection output signal of the detection circuit includes carrier waves such as the oscillation frequency and the high frequency output by the oscillation circuit, this is applied to a low-pass filter or the like. However, it is necessary to set the cutoff frequency to the low frequency side in order to sufficiently cut the oscillation frequency with the low pass filter.

Therefore, if the amount of delay in the phase characteristics in the frequency band in which the angular velocity detector is used becomes too large, there is a problem in that it cannot be ignored in terms of product performance, such as delay in image stabilization control.

Further, if a high-order low-pass filter is formed to solve the problem of phase delay, there is a problem that the circuit becomes complicated.

Further, since the peak level of the differential output signal is attenuated to about 32% of the original level by passing the detected output signal through the low-pass filter, an amplifier circuit must be provided as necessary to cope with this. However, there is a problem that the configuration becomes complicated.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an angular velocity detecting device capable of improving detection accuracy with a simple structure.

[0022]

In order to achieve the above object, an angular velocity detecting device according to a first aspect of the present invention comprises a vibrating medium vibrating by the output of the vibrating means and two sheets for converting the vibration of the vibrating medium into a voltage and outputting the voltage. A set of voltage conversion means, a difference output means for outputting a difference between output voltages of the two sets of voltage conversion means, and an angular velocity detecting device for detecting an angular velocity based on an output of the difference output means, Holding means for holding the output of the difference output means at every predetermined integer cycle of the oscillation cycle of the oscillating means.

In order to achieve the same object, the angular velocity detecting device according to a second aspect of the invention has the same structure as that of the first aspect.
It is characterized in that a set of voltage converting means is arranged so as not to be parallel to the vibration direction of the vibrating medium and to be substantially symmetrical with respect to the central axis.

Further, in order to achieve the same object, claim 3
The angular velocity detecting device of the above 1 is characterized in that, in the configuration of the above-mentioned claim 1, it is provided with a filter means for smoothing the output held by the holding means.

In order to achieve the same object, the angular velocity detecting device according to a fourth aspect is characterized in that, in the structure according to the first aspect, the holding means holds the output of the difference output means at a substantially peak value.

Further, in order to achieve the same object, claim 5
The angular velocity detecting device according to claim 1, further comprising: a calculating unit that calculates a difference between the output value held by the holding unit and a predetermined reference value, and detects the angular velocity based on the calculated difference. It is characterized by

[0027]

According to the angular velocity detecting device of claim 1 of the present invention,
The vibrating medium vibrates due to the output of the oscillating means, the vibration is converted into a voltage by a pair of voltage converting means and is output, and the difference between the output voltages of the voltage converting means is output by the difference output means, and the output is It is held every predetermined integer period of the oscillation period of the oscillating means, and the angular velocity is detected based on the held output.

In the angular velocity detecting device according to a second aspect of the present invention, a set of two voltage converting means is arranged so as to be non-parallel to the vibration direction of the vibration medium and substantially symmetrical with respect to the central axis. .

Further, according to the angular velocity detecting device of the third aspect of the present invention, the output held by the holding means is smoothed.

According to the angular velocity detecting device of the fourth aspect of the present invention, the output of the difference output means is held at a substantially peak value.

Further, according to the angular velocity detecting device of the fifth aspect of the present invention, the difference between the output value held by the holding means and the predetermined reference value is calculated, and the angular velocity is detected based on the calculated difference. .

[0032]

Embodiments of the present invention will be described below.

[First Embodiment] An angular velocity detecting apparatus according to a first embodiment of the present invention will be described with reference to FIGS. 1, 2 and 5. 1 corresponds to FIG. 6 according to the above-mentioned conventional example, FIG. 5 is common, and FIG. 2 corresponds to FIG. 7 according to the conventional example.

Since the configuration of the vibration gyro according to the angular velocity detecting apparatus of this embodiment is the same as that of the conventional example, FIG. 5 is used and its explanation is omitted.

FIG. 1 is a block diagram of the angular velocity detector of this embodiment. In FIG. 1, the same elements as those of FIG. 6 are designated by the same reference numerals, and the description thereof will be omitted. The present embodiment is different only in that a holding circuit 10 is provided instead of the blanking circuit 7 in FIG. 6 and a delay circuit 9 is deleted. The holding circuit 10 uses the timing of the oscillation signal of the oscillation circuit 5, and holds the output signal of the difference circuit 6 at the rising timing, for example.

FIG. 2 is a diagram for explaining the flow of signals in the angular velocity detector of this embodiment.

In the figure, an oscillation signal 51 and piezoelectric elements 41 and 42
The output signals 43 and 44 and the differential signal 61 of the differential circuit 6 are the same as those of the conventional example shown in FIG. Difference signal 6
The output of 1 is held by the holding circuit 10 and is output as a holding voltage (holding signal) 11. In the diagram of the wave indicated by 11 in the figure, the dotted wave indicates the original differential signal 61, and the solid straight line connecting the upper peak points of the dotted wave indicates the holding voltage 11
Is. As shown in the figure, by holding (sampling) the output at the timing of 12a and 12b (the rising timing of the oscillation signal 51) and then holding the output once in one cycle, the difference signal 61 is held at almost the peak point. Voltage 1
1 can be obtained.

Next, the holding voltage 11 is smoothed by the low-pass filter 8 to obtain the angular velocity signal 81b. Here, specifically, a calculation unit such as a CPU for calculating the difference between the angular velocity signal 81b and a predetermined reference value is provided, and the angular velocity is obtained based on the calculated difference. When the low-pass filter 8 is not used, the angular velocity is calculated by the same calculation process based on the holding voltage 11.

As described above, when the oscillation frequency of the oscillation circuit 5 is higher than the fluctuation frequency to some extent, the level difference (oscillation frequency and its high-frequency component) of the signal appearing at the output of the holding circuit 10, that is, the mutual output values of the respective samplings. The difference is significantly smaller than the detection output signal 71 when the blanking means as in the conventional example is used.

As a result, there is no problem even if the cutoff frequency is set higher than that of the conventional example, and there is no need to use a high-order filter structure. Therefore, since the signal level is less attenuated even through the low-pass filter, an amplifier circuit is not required and it contributes to noise reduction. Further, according to the filter in which the cutoff frequency is set to the high frequency side, the adverse effect on the delay of the phase characteristic can be suppressed.

On the other hand, the provision of the holding circuit 10 eliminates the need for detection by the blanking circuit, thus simplifying the structure.

Although the low-pass filter 8 is provided in this embodiment, it is not necessary if the step of the hold output signal 11 is sufficiently small, and the low-pass filter 8 may be omitted. This simplifies the configuration.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. 5, 3 and 4. The vibration gyro according to the angular velocity detecting device of this embodiment is the same as that of the conventional example described above, and therefore FIG. 5 is used as it is.

FIG. 3 corresponds to FIG. 1 according to the first embodiment, and the same elements as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 3, the reference oscillator circuit 102 and the counter 101 correspond to the oscillator circuit 5 of FIG. 1, and the A / D (analog / digital) converter 103 is the holding circuit 1 of FIG.
0, the low-pass filter 104 corresponds to the low-pass filter 8 of FIG.
It is provided inside 00. The output of the microcomputer 100 is through the port 105 and the input is through the port 1.
It will be done through 06.

In FIG. 3, the reference oscillation circuit 102 uses a crystal oscillator or the like and always outputs the reference oscillation signal at a constant cycle. Counter 101 based on the oscillation frequency
Outputs the oscillation signal of the microcomputer by inverting the output logic at every predetermined timing.
This output is equivalent to the oscillation signal 51 of the first embodiment, is supplied to the vibrator 31, and is converted into mechanical vibration (flexing motion) in the vibration direction a. In addition, the A / D converter 1
03 converts the difference signal 61 of the difference circuit 6 into a digital value. This conversion timing is determined by the timing obtained from the counter 101, and is 1 for each output logic inversion cycle.
The conversion is performed near the peak point of the time difference signal 61. The signal thus converted corresponds to the holding voltage 11 in the first embodiment, and the high-pass component is removed by the low-pass filter 104 to obtain the angular velocity signal corresponding to the angular velocity signal 81b in FIG.

FIG. 4 is a flow chart showing the flow of control by the microcomputer 100.

First, in step S1, the reference oscillation circuit 102
The counter 101 counts the oscillating frequency of the reference oscillating signal generated in a fixed cycle, and the counter value is a predetermined value A
If the counter value is not the predetermined value A, it is determined whether the counter value is the predetermined value B (step S2). As a result, the counter value is the predetermined value A,
If none of B, the process returns to step S1 and the counter value is checked again. When the counter value reaches the predetermined value A, the answer in step S1 becomes affirmative (YES), and the port 105
Is set to Low (step S3), and the counter value is checked again.

On the other hand, when the counter value reaches the predetermined value B, the answer to step S2 becomes affirmative (YES), the output logic of the port 105 is set to Hi (step S4), and the counter value of the counter is cleared to 0 ( In step S5), the differential signal input from the port 106 through the vibration gyro 1 and the differential circuit 6 is converted into a digital value by the A / D converter 103 (step S6), and the converted value is processed by the low-pass filter 104 in low-pass arithmetic processing. (Step S7), an angular velocity signal (step S8) is output to an internal memory (not shown), and the process returns to step S1.

The signal flow in this embodiment is as follows:
It is similar to FIG. 2 of the embodiment.

Here, by setting the predetermined value B of the counter to be twice the value of A, the oscillation signal of the microcomputer is obtained as a square wave with a duty ratio of 50%, so that the piezoelectric elements 31 and 32 are driven. desirable.

Further, in this embodiment, two A / D converters are provided, the outputs of the piezoelectric element 41 and the piezoelectric element 42 are converted into digital amounts by the respective A / D converters, and the microcomputer 10
It is also possible to obtain a differential signal by performing arithmetic processing within 0. This eliminates the need for the difference circuit 6 and simplifies the configuration.

By using a microcomputer or the like as the oscillation mechanism and the holding circuit as in this embodiment, the structure can be simplified, and it is particularly effective when the angular velocity signal is processed by the microcomputer.

In the present embodiment, the angular velocity signal is output from the microcomputer 100 as a digital value, but the present invention is not limited to this, and a D / A converter is provided and an analog signal is obtained by D / A conversion. After setting the value, it may be output to the outside.

Also in the present embodiment, the low-pass filter is not always necessary and may be omitted depending on the situation.

In the first and second embodiments, the timing of sampling by the holding circuit 10 and the A / D converter 1
The conversion timing by 03 is set to 1 per oscillation cycle.
However, the number of times is not limited to this, and may be any cycle that is an integral multiple of the oscillation cycle. However, since the held output level is better to be higher, the timing near the peak value of the differential signal 61 (it may be positive or negative, but in the case of a negative value, it is necessary to consider that the output voltage in the angular velocity direction is inverted). It is desirable to adopt. Specifically, it is desirable to sample within the range of ± 70 (deg) with respect to the peak value with respect to the phase value because a larger output than that of the conventional example can be obtained.

In the first and second embodiments, the shape of the vibrating gyro 1 is a regular hexagonal prism, but the shape is not limited to this. However, in order to maintain the detection accuracy, the piezoelectric elements 41, 4
It is necessary to have a shape such that 2 can be arranged so as to be substantially symmetrical with respect to the central axis b of the vibration gyro 1. In addition, it is necessary to consider that the piezoelectric elements 41 and 42 are not arranged in a direction that is completely parallel to the vibration direction a of the vibrators 31 and 32.

In the first and second embodiments, the delay circuit 9 similar to the conventional example is inserted as necessary, so that the holding circuit 10 and the A / D converter 103 are held and the conversion timing is arbitrarily adjusted. You can also do it.

[0059]

According to the angular velocity detecting device of the first aspect of the present invention, the vibrating medium vibrating by the output of the vibrating means and the voltage converting means of a set of two for converting the vibration of the vibrating medium into a voltage and outputting the voltage. A differential output means for outputting a difference between output voltages of the pair of voltage conversion means, and an angular velocity detection device for detecting an angular velocity based on an output of the differential output means,
Since the output of the difference output means is held at every predetermined integer cycle of the oscillation cycle of the oscillation means, it is possible to avoid higher order of the filter means and higher cutoff frequency, or it is possible to omit the filter means, and to make a high level. The angular velocity signal can be obtained, noise can be reduced, and adverse effects due to phase delay can be suppressed. Moreover, a detection circuit is not necessary. As a result, the structure can be simplified and the angular velocity detection accuracy can be improved.

According to the angular velocity detecting device of the second aspect of the present invention, a set of two voltage converting means is arranged so as not to be parallel to the vibration direction of the vibrating medium and to be substantially symmetrical with respect to the central axis. Therefore, it is possible to detect the angular velocity with higher accuracy.

Further, according to the angular velocity detecting device of the third aspect of the present invention, the output held by the holding means is smoothed, so that harmful carrier frequencies and the like can be removed.

According to the angular velocity detecting device of the fourth aspect of the present invention, since the output of the difference output means is held at a substantially peak value, the need for the low pass filter is further reduced and the angle detecting performance is further improved. be able to.

Further, according to the angular velocity detecting device of the fifth aspect of the present invention, the difference between the output value held by the holding means and the predetermined reference value is calculated, and the angular velocity is detected based on the calculated difference. Therefore, more accurate angle detection is possible.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an angular velocity detection device according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining a signal flow in the angular velocity detecting device according to the first embodiment.

FIG. 3 is a configuration diagram of an angular velocity detection device according to a second embodiment.

FIG. 4 is a flowchart showing a control flow of a microcomputer according to the angular velocity detecting device of the second embodiment.

FIG. 5 is a schematic view of a vibrating gyroscope of an angular velocity detecting device according to a conventional example.

FIG. 6 is a configuration diagram of an angular velocity detection device according to a conventional example.

FIG. 7 is a waveform diagram for explaining a signal flow in an angular velocity detecting device according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vibration gyro 2 Vibration body 5 Oscillation circuit 6 Difference circuit 8 Low pass filter 10 Holding circuit 31 Vibrator 32 Vibrator 41 Piezoelectric element 42 Piezoelectric element

Claims (5)

[Claims] 1. A vibrating medium that vibrates according to the output of the oscillation means, a pair of voltage converting means for converting the vibration of the vibrating medium into a voltage and outputting the voltage, and an output of the pair of voltage converting means. A difference output means for outputting a difference in voltage and an angular velocity detection device for detecting an angular velocity based on the output of the difference output means, wherein the output of the difference output means is held at every predetermined integer period of the oscillation period of the oscillation means. An angular velocity detection device comprising a holding means. 2. The angular velocity according to claim 1, wherein the pair of voltage conversion means are arranged so as not to be parallel to the vibration direction of the vibration medium and to be substantially symmetrical with respect to the central axis. Detection device. 3. The angular velocity detecting device according to claim 1, further comprising a filter means for smoothing the output held by the holding means. 4. The angular velocity detecting device according to claim 1, wherein the holding unit holds the output of the difference output unit at a substantially peak value. 5. A calculation means for calculating a difference between the output value held by the holding means and a predetermined reference value, and the angular velocity is detected based on the calculated difference. The angular velocity detection device according to any one of to 4.