JP2000258162A - Temperature compensator piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform highly accurate offset voltage correction for the temp. not existing in a memory in the temp. compensation for an offset output voltage of a piezoelectric oscillator. SOLUTION: An offset compensation value v, an offset gradient coefficient (interpolation coefficient) Δv, a sensitivity compensation value k and a sensitivity gradient coefficient (interpolation coefficient) Δk are stored at each address of a memory means 23 every specified temp. For an offset voltage to a temp. not existing in the memory means 23, the offset voltage generated across a piezoelectric oscillator A can be eliminated or reduced by obtaining the compensation quantity for the temp. from the offset gradient coefficient Δv. The influence due to the sensitivity variation can be also avoided by obtaining the compensation quantity of the output sensitivity for the temp. from the sensitivity gradient coefficient Δk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature compensation device for a piezoelectric vibrator capable of accurately compensating a temperature of a piezoelectric vibrator having an offset voltage characteristic and a sensitivity characteristic that fluctuate in response to a temperature change. .

[0002]

2. Description of the Related Art FIG. 4 is a perspective view showing a piezoelectric vibrator used for a vibration type gyroscope or the like.

The piezoelectric vibrator 1 is, for example, a flat plate made of a constant elastic material such as an elinvar or the like, in which a piezoelectric material is laminated on both front and back surfaces, or formed entirely of a piezoelectric material plate. The tip is branched and formed into three vibrating legs 1a, 1b and 1c. Each vibrating leg 1a,
1b and 1c are provided with drive electrodes (not shown). When AC drive power is supplied to the drive electrode from the drive means, each of the vibrating legs 1a, 1b and 1c
Are driven to vibrate in the X direction, which is the direction in which the vibrating legs are arranged, by the piezoelectric effect.

[0004] Each vibrating leg generates bending deformation vibration in the X direction in the first or several order mode. Also, the vibrating legs 1a on both sides
And 1b are driven in the same phase, and the center vibrating leg 1c is driven so that the phase is 180 degrees different from the phase of the vibrating legs 1a and 1b on both sides. When the direction of the amplitude of the vibrating legs 1a and 1b on both sides at a certain point is the + X direction, the amplitude direction of the central vibrating leg 1c is the -X direction.

When placed in a rotating system about the Z-axis while being driven as described above, a Coriolis force acts on each of the vibrating legs in a direction orthogonal to the vibration driving direction, and each of the vibrating legs has a Y-axis.
Vibrates in the direction. The vibration components due to the Coriolis force also have opposite phases between the vibrating legs 1a and 1b on both sides and the center vibrating leg 1c. When the vibrating legs 1a and 1b on both sides have an amplitude component in the + Y direction due to Coriolis force at a certain point in time, the center vibrating leg 1c has an amplitude component in the -Y direction. In FIG. 4, detection electrodes 1e and 1f are provided on the center vibration leg 1c, and a vibration component in the Y direction due to Coriolis force is detected as a signal having a phase difference from the detection electrodes 1e and 1f by the piezoelectric effect. .

In the gyroscope, the piezoelectric vibrator 1 itself is torsionally deformed due to a change in the ambient temperature at which the gyroscope is installed, and the elastic coefficient of a supporting base material (not shown) for supporting the piezoelectric vibrator 1 changes. Cheap. When these phenomena occur, an offset voltage is generated in the output signal of the piezoelectric vibrator 1 or the sensitivity of the piezoelectric vibrator changes to cause a fluctuation in the amplitude difference of the output signal. Moreover, it is known that these fluctuate in a complicated manner depending on the temperature, and these are superimposed as voltages on the output signals from the detection electrodes 1e and 1f, and a large error is included in the angular velocity.

Conventionally, as means for compensating such an output signal of the gyroscope, correction by a trimmer adjustment, or offset adjustment and sensitivity adjustment of the piezoelectric vibrator itself at room temperature by laser trimming or the like, and then, at each temperature, The compensation of the offset voltage is described in, for example,
This is performed by means described in JP-A-142716 and JP-A-3-162616.

In the means described in the above publication, the piezoelectric vibrator 1 is put in a thermostat in advance, and the temperature is varied at predetermined temperature intervals from a low temperature to a high temperature, and the piezoelectric vibrator 1 is set for each temperature. Is measured, and the measured value is stored in a correction memory as compensation data.Compensation data corresponding to the internal temperature is read from the correction memory, and an offset voltage is calculated based on the compensation data. It was to cancel.

[0009]

[SUMMARY OF THE INVENTION However, in the means described in the above publication, since it performs temperature compensation using the discretely obtained compensation data, e.g., from the previous temperature t ₁ of the following temperature until t ₂ becomes performs temperature compensation using the compensation data when the preceding temperature t _1. Therefore, if the temperature interval of the compensation data stored in the correction memory is wide, the compensation of the detection signal for the temperature between the previous temperature t ₁ and the next temperature t ₂ cannot be performed correctly.

[0010] Further, it is one means to subdivide the temperature between the previous temperature t ₁ and the next temperature t ₂ and store the compensation data in the compensation memory at small temperature intervals. It is difficult to store all of the compensation data for the offset voltage and the sensitivity in the compensation memory over a wide temperature range due to the storage capacity of the compensation memory. Increasing the storage capacity of the correction memory further increases the cost, or the problem of securing the storage space for the correction memory tends to increase the external dimensions of the entire gyroscope. I can't say.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and is intended to compensate for a temperature of a piezoelectric vibrator having an offset voltage characteristic and a sensitivity characteristic which fluctuate in a complicated manner with temperature change with high accuracy. It is an object of the present invention to provide a temperature compensation device for a piezoelectric vibrator.

[0012]

SUMMARY OF THE INVENTION The present invention provides a piezoelectric vibrator having a drive electrode and a detection electrode, a drive means for applying a drive signal to the drive electrode, and a signal detection means for detecting an output signal from the detection electrode. A temperature sensor for detecting a temperature of the piezoelectric vibrator or an ambient temperature of a mounting portion of the piezoelectric vibrator; and an offset compensation value for each temperature at a predetermined interval as temperature compensation data of the piezoelectric vibrator and the temperature. Memory means for storing an interpolation coefficient representing a change in the offset compensation value; interface means for reading the offset compensation value and the interpolation coefficient from the memory means based on the temperature detected by the temperature sensor; and A signal component based on the offset compensation value and the interpolation coefficient is removed from the detected signal, and the signal detected by the signal detection unit is removed. And an offset compensation circuit for removing or reducing the offset component, and is characterized in that is provided.

Further, the present invention provides a piezoelectric vibrator having a drive electrode and a detection electrode, a drive means for applying a drive signal to the drive electrode, a signal detection means for detecting an output signal from the detection electrode, and a piezoelectric vibrator. A temperature sensor for detecting the temperature of the vibrator or the ambient temperature of the installation portion of the piezoelectric vibrator; and a sensitivity compensation value for each temperature at predetermined intervals and a change in the sensitivity compensation value between the temperatures as temperature compensation data for the piezoelectric vibrator. A memory means storing an interpolation coefficient indicating the sensitivity, an interface means for reading the sensitivity compensation value and the interpolation coefficient from the memory means based on a temperature detected by the temperature sensor, and a signal detected from the signal detection means. A sensitivity compensation circuit for changing a gain based on the sensitivity compensation value and the interpolation coefficient to correct the detection sensitivity of the signal detected by the signal detection means. And it is characterized in that it is.

Further, the present invention provides a piezoelectric vibrator having a drive electrode and a detection electrode, drive means for applying a drive signal to the drive electrode, signal detection means for detecting an output signal from the detection electrode, and a piezoelectric vibrator. A temperature sensor for detecting the temperature of the vibrator or the ambient temperature of the installation portion of the piezoelectric vibrator, and a change in the offset compensation value for each temperature at predetermined intervals and the offset compensation value between the temperatures as temperature compensation data for the piezoelectric vibrator. A memory means for storing an interpolation coefficient representing the sensitivity compensation value for each temperature at a predetermined interval and an interpolation coefficient representing a change in the sensitivity compensation value between the temperatures, and the offset compensation based on the temperature detected by the temperature sensor. Interface means for reading out values and sensitivity compensation values and interpolation coefficients related thereto from the memory means, and a signal detected from the signal detection means. An offset compensation circuit for removing a signal component based on the offset compensation value and the interpolation coefficient to remove or reduce an offset component of the signal detected by the signal detection means; and a gain of the signal detected by the signal detection means. Is changed based on the sensitivity compensation value and the interpolation coefficient, and a sensitivity compensation circuit for correcting the detection sensitivity of the signal detected by the signal detection means is provided.

According to the present invention, when the temperature detected by the temperature sensor matches the temperature stored in the memory means, an offset compensation value or a sensitivity compensation value corresponding to the temperature is read from the memory means to directly perform offset voltage correction and correction. Sensitivity correction can be performed. When the temperature is at a temperature other than the predetermined temperature (temperature not stored in the memory means), the temperature among the interpolation coefficients representing the change of the offset compensation value or the sensitivity compensation value for each predetermined temperature stored in the memory means. Can be read from the memory means to perform offset voltage correction and / or sensitivity correction.

In the above, the interpolation coefficient is a slope coefficient obtained by linearly approximating a change in the offset compensation value or the sensitivity compensation value between the temperatures by a linear function. Are preferred.

Thus, even if the offset characteristic (zero point drift characteristic) or the sensitivity characteristic becomes a complicated curve such as a quadratic or cubic curve with respect to a temperature change, an appropriate value for the temperature can be obtained from the interpolation coefficient. Since the correction amount of the offset voltage or the correction amount of the sensitivity can be obtained, more accurate correction can be performed.

Therefore, the variation of the offset output voltage and the sensitivity of the piezoelectric vibrator, which differs for each temperature, can be corrected over a wide temperature range, so that a highly accurate angular velocity can be obtained. This eliminates the need for adjusting the trimmer after the gyro unit is manufactured, and eliminates the need to perform laser trimming on the piezoelectric vibrator, thereby simplifying the manufacturing process.

Further, according to the present invention, since the temperature not stored in the memory means can be corrected by using the interpolation coefficient indicating the change of the offset compensation value or the sensitivity compensation value, the offset compensation value or the sensitivity compensation value can be corrected. Get fine,
Not all of them need to be stored in the memory means. Therefore, since it is not necessary to add a memory unit, it is possible to prevent the space in the gyro unit from expanding. Alternatively, the size of the gyro unit itself can be reduced.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows a temperature compensating device for a piezoelectric vibrator according to the present invention, and is a block diagram for performing output correction of a vibrating gyroscope. FIG. 2 shows an example of temperature characteristics of the piezoelectric vibrator. FIG. 3 is a conceptual diagram showing offset correction in an offset output voltage (0 point drift) characteristic diagram.

In the block diagram of FIG. 1, reference symbol U denotes a piezoelectric vibrator A, a driving means B, a signal detecting means C, a signal amplifying means 11, a temperature compensating device E and a low-pass filter 1
Reference numeral H denotes a host device that obtains an angular velocity output from the gyro unit U, for example, a navigation system.

The piezoelectric vibrator A is, for example, the above-described three-legged tuning fork type vibrator. The drive means B is composed of an AC drive signal source and a drive circuit for supplying predetermined power to the piezoelectric vibrator A. The signal detecting means C is a signal detecting circuit for detecting an output signal generated from the piezoelectric vibrator A, It has a differential amplifier (not shown) and the like.

The temperature compensating device E is provided with an offset compensating circuit 14 and a sensitivity compensating circuit 15, and the offset compensating circuit 14 and the sensitivity compensating circuit 1
5 is connected. The offset compensation circuit 14
Rough adjustment of offset output of piezoelectric vibrator A (first adjustment)
And a second D / A converter 17 for performing fine adjustment (second adjustment) of the first D / A converter 16. Similarly, the sensitivity compensation circuit 15 performs a third D adjustment for performing a coarse adjustment (first adjustment) of the output sensitivity of the piezoelectric vibrator A.
A / A conversion means 18 and fourth D / A conversion means 19 for performing fine adjustment (second adjustment) thereof.

Further, the piezoelectric vibrator A is provided with a temperature sensor 20 for detecting the temperature of the piezoelectric vibrator A or the internal temperature around the piezoelectric vibrator A. The output of the temperature sensor 20 is the second D signal. / A conversion means 17 reference voltage input section 17a
And a reference voltage input section 19a of the fourth D / A conversion means 19.
And A / D conversion means 21. The output characteristic of the temperature sensor 20 itself is represented by a linear line having a certain slope, and therefore generates an output voltage proportional to a temperature change.

The temperature compensator E has a memory means 2
3 are provided. The memory means 23, the first D / A conversion means 16, the second D / A conversion means 17,
The D / A conversion means 18, the fourth D / A conversion means 19, and the A / D conversion means 21 are connected via an interface means 22 mainly composed of a CPU.

A low-pass filter 13 is provided at the last stage of the gyro unit U, and removes unnecessary high frequency component noise and the like from the angular velocity signal output from the temperature compensator E. The host device H is provided with A / D conversion means 31 and is connected to the low-pass filter 13 provided at the last stage of the gyro unit U.

The memory means 23 of the temperature compensator E stores compensation data consisting of offset compensation data V and sensitivity compensation data K. The offset compensation data V is obtained by placing the piezoelectric vibrator A in a thermostat, and measuring the temperature from a low temperature to a high temperature at a predetermined temperature interval Δt (for example, Δt = 0.2 ° C. to 2.0 ° C.). Variable
It is composed of an offset compensation value v obtained for each temperature and an offset slope coefficient (interpolation coefficient) Δv described later. Similarly, the sensitivity compensation data K is composed of a sensitivity compensation value k and a sensitivity gradient coefficient (interpolation coefficient) Δk described later. The offset compensation data V and the sensitivity compensation data K are stored in one table (V, K) =
(V, Δv, k, Δk) are stored in one address in the memory means 23 for each table. Therefore, one address is configured for each temperature interval Δt, and each piece of compensation data from −40 ° C. to + 100 ° C. is stored in the memory means 23.

[0028] The offset compensation value v, based on the temperature characteristics of the offset output voltage of the piezoelectric vibrator A (0 point drift characteristics) shown in FIG. 2A, the reference temperature T ₀ (eg Celsius 25
° C.) the offset output voltage of the piezoelectric vibrator A as a reference (0 point reference V ₀₎ at an offset output voltage P ₁ measured at predetermined temperature interval Delta] t, P _2, ..., the the P _n 0 point reference V The difference (offset amount) from ₀ is represented by the data (v ₁ = P ₁ −
_{V 0, v 2 = P 2} -V 0, ..., is obtained by a _{v n = P 3 -V 0)} .

On the other hand, the offset slope coefficient (interpolation coefficient) Δ
v is set as follows. For example, as shown in FIG.
The offset output voltage follows the offset curve P
P ₁, P_Two, P_ThreeIn the case of changing like
Reference voltage V₀Then, the initial temperature t₁Offset at ℃
Output voltage P₁Is the zero point reference voltage V₀Q on the line₁To the point of
The offset compensation value v₁Is v₁= P₁−
V₀Becomes Similarly, the second temperature t after the increase of Δt ° C._Two(=
t₁+ Δt) Offset output voltage P at ° C._TwoIs the zero-point group
Reference voltage V₀Q on the line_TwoIs corrected to the point of
Reward v_TwoIs v_Two= P _Two-V₀, And after that, similarly after the increase of Δt ° C.
The second temperature t_Three(= T₁Offset at + 2Δt) ° C
Output voltage P_ThreeIs the zero point reference voltage V₀Q on the line_ThreeCorrected to the point
And the offset compensation value v_ThreeIs v_Three= P_Three-V₀Becomes

The change from the first temperature t ₁ ° C to the second temperature t ₂ (= t ₁ + Δt) is (v ₂ -v ₁ ) / Δt
(Straight line P ₁ P ₂ ≡straight line Q ₁ Q _b ), and the second temperature t ₂
The change from the third temperature t ₃ ° C to the third temperature is (v ₃ -v ₂ )
/ Represented by Delta] t (linearly P ₂ P ₃ ≡ linear Q ₂ Q _C).

Therefore, the offset output voltage P₁Is
Initial temperature t₁0 point reference voltage V at ° C₀Q on the line₁of
Point, but the initial temperature t₁° C and the second temperature t_Two
(= T ₁+ Δt) of the offset output signal P_aHako
(V_Two-V₁) / Δt straight line Q₁Q_bupper
Point Q_a'. Therefore, the second temperature t_TwoTo
, Ie, the offset output signal P_TwoIs based on 0 points
Voltage V₀Point Q on line_TwoAnd zero point reference voltage V₀Until it is corrected to
Then the amount of change (v_Two-V₁) / Δt (Line Q₁Q_bCorrected by
It is.

That is, the offset output signal has a predetermined temperature (temperature stored in the memory means) t ₁ , t ₂ , t
_3, ... and if they match, but is accurately temperature corrected zero point reference voltage V _0, the predetermined temperature t _1, t _2, t _3, ... other than temperature, namely a temperature t ₁ and t ₂ the, during which the amount of change when such temperature t _a in the Δt range between, for example, (v ₂ -
_{v 1) / Δt (v 3} -v 2) / Δt, ..., (v n -v n-1)
/ Δt, and is corrected as a triangular wave as a whole.
Therefore, it cannot be accurately corrected to the zero-point reference voltage V ₀ in all temperature ranges.

Therefore, the above (v ₂ −v ₁ ) / Δt, (v ₃
−v ₂ ) / Δt,..., (V _n −v _n−1 ) / Δt, etc., an offset slope coefficient (interpolation coefficient) Δv is set as follows so as to have an opposite slope. .

In the above example, the temperature t₁° C to temperature t_Two
The change in the slope of the triangle wave is (v_Two-V₁) / Δ
t (straight line Q₁Q_b), But the offset tilt to this
Coefficient (interpolation coefficient) Δv₁To Δv₁=-(V_Two-V₁) / Δ
Set to t. Similarly, (v _Three-V_Two) / Δt, ..., (v
_n-V_n-1) / Δt, the offset slope coefficient Δv is
Δv_Two=-(V_Three-V_Two) / Δt, ..., Δv_n= −
(V_n-V_n-1) / Δt. That is, the offset
The gradient coefficient (interpolation coefficient) Δv is the variation of the offset compensation value.
Between the temperature and the next temperature
The slope (for example, the straight line Q₁
Q_b, Straight line Q_TwoQ_C) And the opposite gradient (mathematically, Δ
v_n=-(V_n-V_n-1) / Δt (n is an integer))
It is a slope coefficient. Then, from the slope coefficient, the temperature interval Δ
Determine the amount of offset output voltage correction within t
It is assumed that.

In FIG. 3, among the offset slope coefficients Δv, slopes corresponding to Δv ₁ and Δv ₂ are indicated by broken lines L ₁ and L _{2. In} this example, the offset slope coefficient Δv has a negative slope. Is shown. Note that the offset output voltage (offset curve P) may have a positive slope in some cases.

The sensitivity compensation value k and the sensitivity gradient coefficient (interpolation coefficient) Δk can be set in the same manner as the offset compensation value v and the offset gradient coefficient Δv based on the sensitivity characteristics shown in FIG. 2B. .

The operation of the temperature compensation device for a piezoelectric vibrator constructed as described above will be described. When the piezoelectric vibrator A is placed in a rotating system, output signals having different phase differences proportional to the Coriolis force generated by the rotation are output from the detection electrodes 1e and 1f provided on the piezoelectric vibrator A, respectively (FIG. 4). The phase difference between these output signals is detected by differential amplifying means (not shown) provided in the signal detecting means C in the gyro unit U shown in FIG. 1, and the signal amplifying means 11 outputs an angular velocity output signal Vω. Is output to the temperature compensator E.

At this time, the temperature t at or near the piezoelectric vibrator A is detected by the temperature sensor 20 and is converted into a digital value by the A / D converter 21. The interface 22 reads the digital value, accesses an address in the memory means 23 corresponding to the temperature t, and reads out the offset compensation data V and sensitivity compensation data K written at the address.

The offset compensation value v of the offset compensation data V is determined by the first D / A converter 16.
, The offset slope coefficient (interpolation coefficient) Δv
Are converted into analog signals and supplied to the offset compensation circuit 14. Similarly, of the sensitivity compensation data K, the sensitivity compensation value k is converted by the third D / A converter 18 and the sensitivity gradient coefficient (interpolation coefficient) Δk is converted by the fourth D / A converter 19 into an analog signal. And supplied to the sensitivity compensation circuit 15.

The offset compensation circuit 14 performs a zero-point voltage correction based on the offset compensation value v converted into an analog signal and the offset slope coefficient Δv. This zero-point voltage correction is performed in two stages, a first adjustment (coarse adjustment) and a second adjustment (fine adjustment).

In the first adjustment, a correction based on the offset compensation value v is performed, and the offset output voltages (P ₁ , P ₂ ,..., P _n ) are removed or reduced from the angular velocity output signal Vω.

As shown in FIG. 3, when the temperature detected by the temperature sensor 20 is t ₁ and the offset output voltage of the piezoelectric vibrator A corresponding to the temperature t ₁ is P ₁ , the output of the signal detecting means C In the angular velocity output signal Vω, the offset output voltage P ₁ is superimposed on the angular velocity output voltage Vω ′ generated by rotation (Vω = Vω ′ + P ₁ ). By removing or reducing the offset output voltage P ₁ from Vω ′, that is, by correcting it with the offset compensation value v ₁ , a highly accurate angular velocity output voltage Vω ′ can be obtained (Vω ′ =
_{Vω-v 1 = Vω- (P} 1 -V 0)).

In the first adjustment, every time the signal is output from the signal detecting means C at a predetermined cycle, that is, each time the angular velocity output signal Vω is detected from the phase difference of the piezoelectric vibrator A, the signal is synchronized with this cycle. said angular rate output signal Vomega offset output voltage P ₁ corresponding to the time the temperature from is removed, accurate angular rate output voltage Vomega 'is obtained Te.

[0044] Thus, as with temperature t _1, the temperature t ₂ the detected temperature of the temperature sensor 20 is stored in the memory means 23, ..., when matching the t _n, the from the angular velocity output signal Vω The offset voltage can be removed with the offset compensation value v corresponding to the temperature at the time, and the angular velocity output voltage Vω ′ can be obtained with high accuracy.

However, as described above, when the detected temperature from the temperature sensor 20 does not match the temperatures t ₁ , t ₂ ,..., T _n ° C. stored in the memory means 23, that is, the temperature sensor 20 detects A temperature (for example, t _a ) within a predetermined temperature interval Δt ° C. is detected, such as a temperature between t ₁ ° C. and t ₂ ° C., a temperature between t ₂ ° C. and t ₃ ° C. In this case, the following correction is performed by the second adjustment using the offset slope coefficient (interpolation coefficient) Δv.

Temperature at which angular velocity output signal Vω is detected
If the temperature is within the temperature interval Δt ° C., for example, the temperature t₁℃
Temperature t_Two° C (Δt = t₁-T_Two) Temperature t_a° C (t₁<
t_a<T_Two) Will be described with reference to FIG.
I do. Note that the temperature t₁Offset compensation data for ° C
TA V₁And the temperature t_TwoOffset compensation data V for ° C
_TwoAre both stored in the memory means 23.

[0047] As described above, in the first adjustment to the offset output voltage P _a at a temperature t _a ° C. (offset correction value = v _1), the offset output voltage P _a on the offset curve P (v ₂ -v ₁ ) is corrected to / Delta] t (linearly Q ₁ Q _b) on a point Q _a '. Thus, the second adjustment is corrected to a point Q _a 'on the straight line Q ₁ Q _b and a point Q _a on zero point reference voltage V _0.

[0048] From FIG. 3, the straight line Q ₁ Q _b Q _a point on the 'correction amount to a zero point reference voltage V ₀ is, (- (Q _a' is -V _0)). Therefore, 'the length of the perpendicular foot dropping off from the zero point reference voltage V ₀ is the may be known, where the correction amount (- (Q _a' point Q _a -V _0)), the offset slope factor Using Δv ₁ , − (Q _a ′ −V ₀ ) = Δv ₁ × t _a = −
_{(V 2 -v 1) / Δt} 1 can be determined as × t _a.

[0049] That is, the correction amount _{(- (Q a '-V 0} ))
Approximates an offset curve P between the temperature t ₁ ° C and the temperature t ₂ ° C as a straight line P ₁ P _2, and a slope coefficient Δv ₁ = − (v ₂
-V ₁₎ / Delta] t to be determined by multiplying the temperature t _a ° C. at that time, the correction value in the first adjustment (point Q _a ')
The correction amount calculated in this way _{(- (Q a '-V 0} ))
By adding, can be corrected point Q _a 'to point Q _a on zero point reference voltage V _0.

[0050] Thus, the offset voltage P _a on the offset curve P in the first adjustment is corrected in terms of Q _a 'in the first adjustment, further second adjustment by a point on the 0-point reference voltage V ₀ it can be corrected to the Q _a.

The offset slope coefficient Δv ₁ (= −
(V ₂ −v ₁ ) / Δt) is converted to an analog value by the second D / A converter 17, and the offset compensation value v ₁ is converted to an analog value by the first D / A converter 16 in the same manner as described above. You. Then, the offset compensation circuit 14 adds or subtracts the analog value of the offset slope coefficient Δv ₁ and the analog value (correction amount) of the offset compensation value v ₁ from the angular velocity output signal Vω at that temperature (t _a ). ,
An angular velocity output signal Vω 'is obtained.

The angular velocity output signal V thus obtained
ω ′ is highly accurate because the superposition error due to the offset voltage has been removed. The angular velocity output signal Vω ′ thus obtained is sent to the host device H after unnecessary high frequency components are removed by the low-pass filter 13.

On the host device H side, the angular velocity output signal V
The angle is calculated by A / D conversion of ω ′ and numerical integration, and is used as an internal signal of the navigation system.

The calculation for multiplying the slope coefficient by the output from the temperature sensor 20 may be performed not by digital calculation but by analog calculation. Furthermore, the D / A conversion means 17
Is changed based on the output of the temperature sensor 20 to perform the same operation as multiplication.

As described above, the offset compensation value v and the offset slope coefficient (interpolation coefficient) Δv discretely obtained
Is stored in the memory means 23, it is also possible to correct the offset voltage P for a temperature not present in the memory means 23. Therefore, since it is not necessary to store the compensation data in the memory means 23 in detail, it is possible to remove or reduce the offset voltage P generated in the piezoelectric vibrator A over a wide temperature range with a small amount of compensation data.

In the above description, the offset voltage compensation has been mainly described. However, the same method is used for sensitivity compensation by correcting the amount of change (amplitude) of the voltage of the piezoelectric vibrator at a predetermined temperature as a reference sensitivity. It can be used to correct.

In the above description, the piezoelectric vibrator has been described as an example. However, it is also possible to perform temperature correction such as offset voltage and output sensitivity included in other elements having complicated fluctuations. Further, the present invention can be applied not only to the case of temperature fluctuation but also to the case where other parameters fluctuate.

[0058]

According to the present invention described above, offset correction and / or sensitivity correction for a temperature not stored in the memory means is performed using the offset gradient coefficient and / or the sensitivity gradient coefficient (interpolation coefficient). be able to. Therefore, there is no need to obtain the offset compensation value and / or the sensitivity compensation value finely, and no additional memory means is required.

In the present invention, the temperature can be compensated only by the correction data in the memory means.
There is no need to adjust the trimmer after the unit is manufactured. Further, it is not necessary to perform laser trimming of the piezoelectric vibrator, so that the manufacturing process can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a temperature compensation device for a piezoelectric vibrator according to the present invention and performing output correction of a vibratory gyroscope;

FIG. 2 shows an example of a temperature characteristic of a piezoelectric vibrator, wherein A is an offset output voltage (zero point drift) characteristic diagram, B is a sensitivity characteristic diagram,

FIG. 3 is a conceptual diagram showing offset correction in an offset output voltage characteristic diagram;

FIG. 4 is a perspective view showing a piezoelectric vibrator used for a vibration type gyroscope or the like;

[Explanation of symbols]

14 offset compensation circuit 15 sensitivity compensation circuit 16 first D / A conversion means 17 second D / A conversion means 18 third D / A conversion means 19 fourth D / A conversion means 20 temperature sensor 21 A / D conversion means 22 Interface means 23 Memory means K Sensitivity compensation data k Sensitivity compensation value Δk Sensitivity slope coefficient (interpolation coefficient) V Offset compensation data v Offset compensation value Δv Offset slope coefficient (interpolation coefficient) V ₀ 0 point reference voltage T ₀ Reference temperature Δt Temperature interval A Piezoelectric vibrator B Drive means C Signal detection means E Temperature compensator H Host equipment P Offset curve U Gyro unit

Claims (4)

[Claims] 1. A piezoelectric vibrator having a drive electrode and a detection electrode, drive means for providing a drive signal to the drive electrode, signal detection means for detecting an output signal from the detection electrode, and a temperature of the piezoelectric vibrator. Alternatively, a temperature sensor that detects the ambient temperature of the installation portion of the piezoelectric vibrator, and an interpolation that represents, as temperature compensation data for the piezoelectric vibrator, an offset compensation value for each temperature at predetermined intervals and a change in the offset compensation value between the temperatures. A memory means for storing coefficients, an interface means for reading the offset compensation value and the interpolation coefficient from the memory means based on the temperature detected by the temperature sensor, and the offset compensation based on a signal detected from the signal detection means. The signal component based on the value and the interpolation coefficient is removed, and the offset component of the signal detected by the signal detecting means is removed. And an offset compensating circuit for reducing the temperature. 2. A piezoelectric vibrator having a drive electrode and a detection electrode, drive means for providing a drive signal to the drive electrode, signal detection means for detecting an output signal from the detection electrode, and a temperature of the piezoelectric vibrator. Alternatively, a temperature sensor for detecting the ambient temperature of the installation portion of the piezoelectric vibrator, and an interpolation representing a sensitivity compensation value for each temperature at predetermined intervals and a change in the sensitivity compensation value between the temperatures as temperature compensation data for the piezoelectric vibrator. A memory means for storing coefficients, an interface means for reading the sensitivity compensation value and the interpolation coefficient from the memory means based on the temperature detected by the temperature sensor, and a gain of a signal detected from the signal detection means. A sensitivity compensation circuit for changing the sensitivity based on the sensitivity compensation value and the interpolation coefficient to correct the detection sensitivity of the signal detected by the signal detection means. A temperature compensation device for a piezoelectric vibrator, characterized in that: 3. A piezoelectric vibrator having a drive electrode and a detection electrode, drive means for providing a drive signal to the drive electrode, signal detection means for detecting an output signal from the detection electrode, and a temperature of the piezoelectric vibrator. Alternatively, a temperature sensor that detects the ambient temperature of the installation portion of the piezoelectric vibrator, and an interpolation that represents, as temperature compensation data for the piezoelectric vibrator, an offset compensation value for each temperature at predetermined intervals and a change in the offset compensation value between the temperatures. Memory means for storing a coefficient and a sensitivity compensation value for each temperature at a predetermined interval and an interpolation coefficient representing a change in the sensitivity compensation value between the temperatures; and an offset compensation value and a sensitivity based on a temperature detected by the temperature sensor. An interface unit for reading out a compensation value and an interpolation coefficient relating thereto from the memory unit; and the offset compensation unit based on a signal detected by the signal detection unit. An offset compensating circuit for removing a signal component based on the compensation value and the interpolation coefficient to remove or reduce an offset component of the signal detected by the signal detecting means; and A sensitivity compensation circuit for changing the sensitivity based on the sensitivity compensation value and the interpolation coefficient to correct the detection sensitivity of the signal detected by the signal detection means. 4. The interpolation coefficient is a slope coefficient obtained by linearly approximating a change in the offset compensation value or the sensitivity compensation value between temperatures by a linear function. Item 4. The temperature compensation device for a piezoelectric vibrator according to any one of Items 1 to 3.