JPH05141969A - Inclination sensor - Google Patents

Abstract

PURPOSE:To suppress the temperature drift to the minimum when many frequencies are detected and improve the measurement precision of the inclination angle by setting two SAW resonators to the analogous pattern, and making the summit temperature of them equal. CONSTITUTION:Transmitting electrodes 5a and receiving electrodes 6a of an SAW resonator 4a are arranged at a preset interval, and reflectors 8a, 9a are formed at symmetrical positions on the outside of the electrodes 5a and the electrodes 6a. The distance between the reflectors 8a, 9a is set to LC1, and the effective distance in the reflectors 8a, 9a respectively is set to delta1. Transmitting electrodes 5b, receiving electrodes 6b, and reflectors 8b, 9b are likewise formed on a resonator 4b. The distance between the reflectors 8b, 9b is set to LC2, and the effective distance in the reflectors 8b, 9b is set to delta2. The resonators 4a, 4b are set to the analogous pattern, thus LC1/delta1) and (LC2/delta2) are made equal, and both summit temperatures (temperature at the peak resonance frequency) can be made equal. The frequency difference generates no or very little measurement error due to the difference of temperature characteristics, and high-precision detection can be made.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilt sensor for detecting a minute tilt angle with high accuracy by using SAW technology.

[0002]

2. Description of the Related Art Conventionally, a SAW tilt sensor of this type is known, for example, as shown in FIG. In FIG. 3, reference numeral 1 is a cantilever made of a quartz substrate, one end of the cantilever 1 is fixed to a fixing portion 2 such as a sensor housing, and the other end is free and a weight 3 is attached.

Electrode patterns forming SAW resonators 4a and 4b are formed on the upper and lower surfaces of the quartz substrate forming the cantilever 1, respectively. The electrode patterns of the SAW resonators 4a and 4b are the transmitting electrodes 5a and 5b and the receiving electrodes 6a and 6b.
b is arranged, and the array pattern of the reflectors 8a, 9a and 8b, 9b is formed on the outside thereof. SAW resonators 4a, 4
The outputs of the receiving electrodes 6a and 6b of the antenna b are positively fed back to the transmitting electrodes 5a and 5b by the amplifiers 10 and 11, whereby the SA
W oscillator 12a, and 12b configured to oscillate a signal of a frequency f _1, f _2.

Oscillation signals from the SAW oscillators 12a and 12b are input to a mixer 14 to detect a frequency difference (f ₁ -f ₂ ) and output via a bandpass filter (BPF) 15 to remove unnecessary components. To do. FIG. 4 shows the actual arrangement of the cantilever 1 in the tilt sensor. That is, when the tilt angle θ is zero, the cantilever 1 is vertical,
When the tilt angle θ is generated as shown in the figure, the weight 3 causes extensional strain on the formation surface of the SAW resonator 4a on the right side of the cantilever 1, and at the same time, compressive strain is generated on the formation surface of the SAW resonator 4b on the left side.

FIG. 5 shows the electrode pattern of the SAW resonator of FIG. 4 in an extracted form, and reflectors 8 and 9 using a delay line array pattern are arranged at symmetrical positions outside the transmitting electrode 5 and the receiving electrode 6. Has been done. The resonance frequency f of the SAW resonator of FIG. 5 is: f = m × V / (L _c + δ) (1) where m is a value of about a hundred and several tens in terms of harmonic order V; SAW on a ST cut quartz substrate Propagation velocity L _c ; Distance between reflectors δ; Effective distance within reflector.

Further, the resonance frequency f of the SAW resonator has temperature dependence shown by the following equation. f = f ₀ {1-a (T−T ₀ ) ² } (2) where f ₀ : Resonance frequency at apex temperature T ₀ a; Material constant 3 × 10 ⁻⁸ T in the case of crystal; actual Ambient temperature T ₀ ; apex temperature As shown in FIG. 6, the apex temperature T _{0 of the} equation (2) is a characteristic that the resonance frequency f exhibits a peak value at a certain temperature, and the resonance frequency f decreases at temperatures before and after that. Therefore, the frequency of this peak value is called f ₀ , and the temperature of the peak frequency f ₀ is called the apex temperature T ₀ .

Next, a method for making the oscillation frequencies f ₁ and f ₂ of the two ASW oscillators 12 and 14 different to detect the tilt angle will be described. First, assuming that the peak temperatures T ₁₀ and T _{20 of the} SAW resonators 12 and 14 are the resonance frequencies f ₁₀ and f ₂₀ at the peak temperatures T ₁₀ and T ₂₀ , the oscillation frequencies f ₁ and f
₂ is given by _{f 1 = f 10 {1-} a (T-T 10) 2 -bθ} (3) f 2 = f 20 {1-a (T-T 20) 2 + bθ} (4).

Note that θ in equations (3) and (4) is exactly sin
θ, but since the inclination angle θ is extremely small, sin
There is no problem in handling as θ = θ. Therefore, the frequency difference F is F = (f ₁ −f ₂ ) = Δf {1-at ² + 2a (f ₁₀ / Δf) ΔT · t} + b (f ₁₀ + f ₂₀ ) θ (5) where Δf = f ₁₀ −f ₂₀ ΔT; difference between peak temperatures (T ₁₀ −T ₂₀ ) t; difference between actual temperature and peak temperature (T−T ₂₀ ). Here, b is b = (9Wx / ED ² e) (6) where W: weight of weight x: distance from center of weight to center of resonator E: Young's modulus of crystal D: thickness of crystal substrate e; given by the width of the quartz substrate.

The two SAW oscillators 12a and 12b shown in FIG.
In order to make the oscillation frequencies f ₁ and f ₂ of (1) different,
As is clear from the equation, the inter-reflector distance L _c in the SAW resonators 4a and 4b may be changed. Figure 7 shows the conventional SA
W resonator 4a, which was shown by comparing the electrode structure 4b, by slightly shortening the reflector distance L _c2 reflector distance L _c1 with respect to e.g. SAW resonator 4b of SAW resonators 4a The resonance frequencies that determine the oscillation frequencies f ₁ and f ₂ are made different. In this case reflectors 8a and 8b, 9a and 9b
The effective distance δ in the reflector and the pitch d of each electrode array pattern are the same and do not change.

[0010]

However, in a SAW tilt sensor having a structure in which SAW resonators are formed on both surfaces of one conventional cantilever as described above, two SW tilt sensors are used.
There is a problem that a large temperature drift occurs in the difference frequency F due to the difference in the temperature characteristics of the AW resonator, and the measurement error increases.

That is, the difference frequency F of the SAW tilt sensor is
It is given by the above equation (5), and [2a (f ₁₀ / Δ
f) The value of the [ΔT] term becomes a considerably large value. For example, when the actual temperature t is set to t = 10 ° C., the value of the term [2a (f ₁₀ / Δf) ΔT] with respect to the temperature difference ΔT between the peak temperatures T ₁₀ and T ₂₀ is, for example, ΔT = 1 ° C. and [2a ( f ₁₀ /Δf)ΔT]=1.5×10 ^−3, and the measurement error becomes large because the temperature drift is large.

The present invention has been made in view of such conventional problems, and it is an object of the present invention to provide an inclination sensor using the SAW technique, which can suppress the temperature drift and dramatically improve the measurement accuracy. To aim.

[0013]

To achieve this object, the present invention is constructed as follows. The reference numerals in the drawings are also shown. First, the present invention is directed to a cantilever 1 made of a quartz substrate with one end fixed and the other end free and a weight 3 attached.
And a pair of SAW resonators 4a and 4b having different resonance frequencies formed on the front and back surfaces of the cantilever 1, respectively.
Resonator 4a, a pair of SAW oscillator 12a oscillating a signal of frequency f _1, f ₂ to the output of 4b positive feedback to match the resonant frequency, and 12b, a pair of SAW oscillators 12a, 1
Mixer 1 for detecting the frequency difference F (= f ₁ −f ₂ ) of 2b
4 and the tilt sensor that detects the tilt angle θ of the cantilever 1 with respect to the vertical axis based on the frequency difference F output from the mixer 14 are symmetrical.

The present invention relates to such an inclination sensor.
The pair of SAW resonators 4a and 4b are mounted on a quartz substrate.
Electrode array of transmitting electrodes 5a and 5b and receiving electrodes 6a and 6
b electrode array is arranged and transmitting electrodes 5a, 5b and
And the reflectors 8a, 6a, 6b at symmetrical positions outside the receiving electrodes 6a, 6b.
8b, 9a, 9b array structure is formed
And the distance between the reflectors in one SAW resonator 4a
L_c1, Effective distance in reflector δ ₁ And array pitch d₁ Against
And the distance between the reflectors in the other SAW resonator 4b
L_c2, Effective distance in reflector δ₂ And array pitch d₂ The regulation
Similar pattern with a size ratio K that gives a constant frequency difference F
And the apex temperature T between the pair of SAW resonators_Ten, T ₂₀Difference
The feature is that ΔT is suppressed to zero or minimum.

Further, in the tilt sensor of the present invention, the composition ratio (L _c / δ) between the inter-reflector distance L _c of the pair of SAW resonators 4a and 4b and the intra-reflector effective distance δ is defined as follows. Ratio L
It is characterized in that it is set to a value at or near the inflection point where the change in the apex temperature T ₀ is minimum with respect to the change in _c / δ.

[0016]

In the tilt sensor of the present invention having such a configuration, as the electrode pattern of the SAW resonator provided on both sides of the quartz substrate forming the cantilever, one pattern is defined as the other pattern, for example, K = Even if the inter-reflector distance L _c is changed in order to make the oscillation frequency different, by using a similar pattern with a magnification of 0.9996, two S
The composition ratio (L _c / δ) of the AW resonator can be the same, and if the composition ratio (L _c / δ) is the same, the apex temperature is also the same. Therefore, the apex temperature difference ΔT is zero or the pole. It can be a very small value.

As a result, the frequency difference F becomes F = (f ₁ −f ₂ ) = Δf (1−at ² ) + b (f ₁₀ + f ₂₀ ) θ, and [2a (f ₁₀ / Δf) ΔT
Since the term [t] is eliminated, a measurement error due to the difference in temperature characteristics will not occur, or can be negligible.
Inclination angle detection accuracy of the order of 1/100 degree can be achieved.

In the actual manufacturing process, two S
Even if the AW resonator has a similar pattern, the thickness and width of the electrodes vary during the manufacturing process, and it is difficult to make the vertex temperatures the same. Therefore, in the present invention, as the operating characteristics of the SAW resonator, the composition ratio (L) between the inter-reflector distance L _c of the pair of SAW resonators 4a and 4b and the intra-reflector effective distance δ is set.
_When changing _c / δ), pay attention to the fact that there is an inflection point where the apex temperature hardly changes, and set the composition ratio (L _c / δ) so as to be a value at or near this inflection point. As a result, even if dimensional variations occur in the shape of the electrode pattern during the manufacturing process, changes in the vertex temperature can be minimized, and as a result, a tilt sensor with extremely small temperature error can be manufactured.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a constitutional view of an embodiment showing the electrode arrangement of SAW resonators formed on both sides of a quartz substrate which constitutes a cantilever of a SAW tilt sensor of the present invention. In FIG. 1, 4a and 4b are SAW resonators, one end of which is supported by a fixed portion 2 and a weight 3 is attached to the other end of the cantilever 1 which is free as shown in FIG. Is formed on each of the surfaces on both sides of.

In one SAW resonator 4a, a transmitting electrode 5a and a receiving electrode 6a are arranged at a predetermined distance, and the transmitting electrode 5a
And reflectors 8a and 9a at symmetrical positions outside the receiving electrode 6a.
Is formed. Here, the reflector 8 of the SAW resonator 4a
The distance between the reflectors between a and 9a is L _c1 , and the effective distance within the reflector in each of the reflectors 8a and 9a is δ ₁ .

On the other hand, the other SAW formed on the opposite surface side
Also in the resonator 4b, reflectors 8b and 9b are formed at symmetrical positions outside the transmitting electrode 5b and the receiving electrode 6b, the inter-reflector distance between the reflectors 8b and 9b is L _c2 , and The effective distance within the reflector at 8b and 9b is δ ₂ . In the SAW resonators 4a and 4b of FIG. 1, the electrode patterns of both are similar patterns. That is, SA
If the pattern size of the W resonator 4a is P1, the other S
The pattern size P2 of the AW resonator 4b is the pattern size P1.
Is multiplied by a magnification K which is slightly larger or slightly smaller than 1, and there is a dimensional relationship of P1 = K × P2 between them, that is, both are similar patterns.

More specifically, the inter-electrode distances L _c1 and L _c2 in the SAW resonators 4a and 4b and the effective distances δ ₁ and δ in the reflector.
₂ and the electrode pitches d ₁ and d ₂ , the following relational expressions hold. L _c1 = K · L _c2 δ ₁ = K · δ ₂ (7) d ₁ = K · d ₂ As described above, the two SAW resonators 4a and 4b are made to have a similar pattern, so that the peak temperatures T ₁₀ and T of the two SAW resonators ₂₀ can be made the same, and the temperature drift term 2a (f ₁₀ / Δf) ΔT in the equation (5) can be made zero.

FIG. 2 shows the SAW resonator used in the present invention.
And the distance between reflectors L_c And the effective distance in the reflector δ
(L_c / Δ) apex temperature T with respect to₀ Characteristics showing the relationship of
It is a figure. The characteristic diagram of FIG. 2 shows that the present inventors
In order to solve the problem of temperature drift in the tilt sensor,
A simulator that realizes the operation function of the SAW tilt sensor
Create and use this simulator to calculate the composition ratio (L_c /
δ) is changed and the peak temperature T ₀ Discovered when considering the fluctuation of
Then, further theoretical study was conducted to obtain the characteristics shown in FIG.
I was able to confirm that.

As is clear from the characteristics shown in FIG. 2, the composition ratio (L) between the inter-reflector distance L _c and the intra-reflector effective distance δ shown on the horizontal axis.
It was found that the apex temperature T ₀ periodically changes so as to form a substantially sinusoidal curve with respect to the change of _c / δ). This Figure 2
The following can be understood from the characteristics of. First, in the conventional pattern shown in FIG. 7, since the reflector effective distance δ is not changed by changing only the inter-reflector distance L _c , the composition ratio (L _c / δ)
Varies from SAW resonator to SAW resonator, resulting in a difference in peak temperature.

On the other hand, in the present invention, as shown in FIG. 1, the two SAW resonators 4a and 4b have similar patterns so that the distances between the reflectors are different from L _c1 and L _c2. The composition ratio (L _c1 / δ) between the effective distances δ ₁ , δ ₂ in the reflector
₁ ) and (L _c2 / δ ₂ ) are equal, and the position of the horizontal axis in FIG. 2 does not change. Therefore, in the SAW resonator 4a, 4b of the present invention shown in FIG. 1, determines the peak temperature at any one point on the characteristic curve of FIG. 2, naturally peak temperature T ₁₀
= T ₂₀ .

In this way, if the apex temperatures T ₁₀ and T _{20 of the} two SAW resonators 4a and 4b are equalized by the similar pattern, the apex temperature difference ΔT = 0, and therefore (5) above.
The formula is F = Δf (1-at ² ) + b (f ₁₀ + f ₂₀ ) θ (8), and the temperature drift term 2a (f ₁₀ / Δf) ΔT can be eliminated.

Next, a second embodiment of the present invention will be described. In the second embodiment of the present invention, as shown in FIG. 1, the two SAW resonators 4a and 4b have similar patterns, and at the same time, the composition ratio of the inter-reflector distance and the effective recording distance within the reflector ( The value of L _c / δ) is taken as the value at the point A of the mountain portion or its vicinity or the value of the point B of the valley portion or its vicinity in the characteristic curve of FIG.

At the inflection points A and B in this characteristic curve and in the vicinity thereof, it is apparent that the shift amount of the vertex temperature is small with respect to the variation of the composition ratio (L _c / δ). Thus, the ratio of the distance between reflectors to the effective distance within the reflector (L _c
/ Δ) is determined to be a value at the inflection points A and B or in the vicinity thereof, so that dimensions such as thickness and width produced when the electrode patterns of the SAW resonators 4a and 4b shown in FIG. 1 are manufactured. It is possible to minimize the difference ΔT between the peak temperatures T ₁₀ and T ₂₀ due to the variation in temperature.

That is, at the design stage, the same composition ratio (L _c / δ)
Even if the dimension of the similar pattern is obtained, the thickness, width, etc. of the electrode must be changed due to various factors at the manufacturing stage of forming the electrode patterns shown in FIG. 1 on both sides of the quartz substrate. There will be variations. When the dimensional relationships of the electrode patterns are varied in this way, the similarity of the patterns is broken, and as a result, a temperature difference ΔT occurs between the vertex temperatures T ₁₀ and T ₂₀ of the two, and it becomes impossible to eliminate or reduce the temperature drift term. ..

[0030] In contrast the inflection point A of FIG. 2, B or Composition ratio (L _c / δ) become as reflectors distance value in the vicinity thereof, the reflectors within the effective distance, further decide electrode pitch As a result, even if the thickness or width of the electrode pattern varies during the manufacturing process, the inflection point A,
Even if the composition ratio (L _c / δ) changes in B and its vicinity, the apex temperature does not shift so much, and the apex temperature difference ΔT due to variations in manufacturing is minimized, resulting in the temperature of the formula (3). The drift term 2a (f ₁₀ / Δf) ΔT can be set to an extremely small value to improve the measurement accuracy of the tilt angle.

As the characteristics of the SAW resonators 4a and 4b used in the SAW sensor of the present invention shown in FIG. 1, for example, 196 MHz band is used as the oscillation frequencies f ₁ and f ₂ , and the difference frequency F = 80 kHz between them. If the distance between reflectors L
_{Between c1} and L _c2 , L _c1 = 0.9996 × L _c2 L _c2 = 1991 μm. When the SAW resonator having this similar pattern was created and the peak temperatures T ₁₀ and T ₂₀ were calculated, T ₁₀ = 2.98 ° C.
T ₂₀ = 2.88 ° C., and the peak temperature difference ΔT could be suppressed to 0.1 ° C.

[0032]

As described above, according to the present invention, the two SAW resonators have similar patterns so that the peak temperatures of the two SAW resonators are the same and the temperature drift in the detection of multiple frequencies is eliminated or minimized. The measurement accuracy of the tilt angle can be improved by suppressing it. Furthermore, by setting the composition ratio of the inter-reflector distance in the electrode pattern and the effective distance within the reflector to a value at or near the inflection point where the variation of the apex temperature is small, this occurs at the manufacturing stage of the SAW sensor having a similar pattern. The peak temperature difference can be suppressed to the minimum with respect to the variation in the thickness and width of the electrode pattern, and the yield at the manufacturing stage for forming a fine similar electrode pattern can be significantly improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment showing an embodiment of the present invention by comparing electrode patterns of two SAW resonators.

FIG. 2 is a characteristic diagram showing a relationship of a shift amount of apex temperature with respect to a composition ratio of a distance between reflections and an effective distance in a reflector, which is a principle of the present invention.

FIG. 3 is a structural explanatory view of a tilt sensor.

FIG. 4 is an explanatory view showing a mounting state of a cantilever used for a tilt sensor.

FIG. 5 is an explanatory diagram of an electrode pattern of a SAW resonator used for a tilt sensor.

FIG. 6 is a characteristic diagram showing the relationship between the resonance frequency of the SAW resonator and temperature.

FIG. 7 is an explanatory diagram showing a dimensional relationship for making resonance frequencies different in a conventional SAW resonator.

[Explanation of symbols]

 1: Cantilever (quartz substrate) 2: Fixed part 3: Weight 4a, 4b: SAW resonator 5a, 5b: Transmitting electrode 6a, 6b: Receiving electrode 8a, 8b, 9a, 9b: Reflector 10, 11: Amplifier 12a, 12b: SAW oscillator 14: Mixer

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[Procedure amendment]

[Submission date] December 19, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art Conventionally, a SAW tilt sensor of this type is known, for example, as shown in FIG. In FIG. 3, reference numeral 1 denotes a cantilever made of, for example, a quartz substrate. One end of the cantilever 1 is fixed to a fixed portion 2 such as a sensor housing, and the other end is free and a weight 3 is attached.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

FIG. 5 shows the electrode pattern of the SAW resonator of FIG. 4 in an extracted form, and reflectors 8 and 9 using a delay line array pattern are arranged at symmetrical positions outside the transmitting electrode 5 and the receiving electrode 6. Has been done. The resonance frequency f of the SAW resonator of FIG. 5 is: f = m × V / (L _c + δ) (1) where m; SAW propagation velocity on the quartz substrate L _c ; Distance between reflectors δ It is determined by the effective distance within the reflector.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

Further, the resonance frequency f of the SAW resonator has temperature dependence shown by the following equation. f = f ₀ {1-a (T−T ₀ ) ² } (2) where f ₀ : Resonance frequency at apex temperature T ₀ a; Material constant of quartz, about 3 × 10 ⁻⁸ T; Actual Ambient temperature T ₀ ; vertex temperature As shown in FIG. 6, the vertex temperature T _{0 of the} equation (2) shows a peak value of the resonance frequency f at a certain temperature, and the resonance frequency f decreases before and after the temperature. The frequency of this peak value is referred to as f ₀ , and the temperature of the peak frequency f ₀ is referred to as the apex temperature T ₀ .

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

Note that θ in equations (3) and (4) is exactly sin
θ, but since the inclination angle θ is extremely small, sin
There is no problem in handling as θ = θ. Therefore, when ΔT is small
In this case, the frequency difference F is F = (f ₁ −f ₂ ) = Δf {1-at ² + 2a (f ₁₀ / Δf) ΔT · t} −b (f ₁₀ + f ₂₀ ) θ (5) where Δf = f ₁₀ −f ₂₀ ΔT; difference in peak temperature (T ₁₀ −T ₂₀ ) t; difference between actual temperature and peak temperature (T−T ₂₀ ). Here, b is b = (9Wx / ED ² e) (6) where W: weight of weight x: distance from center of weight to center of resonator E: Young's modulus of crystal D: thickness of crystal substrate e; given by the width of the quartz substrate.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

[0013]

To achieve this object, the present invention is constructed as follows. The reference numerals in the drawings are also shown. First, the present invention relates to a cantilever 1 made of a piezoelectric substrate on which one end is fixed and the other end is free and a weight 3 is mounted.
And a pair of SAW resonators 4a and 4b having different resonance frequencies formed on the front and back surfaces of the cantilever 1, respectively.
Resonator 4a, a pair of SAW oscillator 12a oscillating a signal of frequency f _1, f ₂ to the output of 4b positive feedback to match the resonant frequency, and 12b, a pair of SAW oscillators 12a, 1
Mixer 1 for detecting the frequency difference F (= f ₁ −f ₂ ) of 2b
4 and the tilt sensor that detects the tilt angle θ of the cantilever 1 with respect to the vertical axis based on the frequency difference F output from the mixer 14 are symmetrical.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

The present invention relates to such an inclination sensor.
Then, the pair of SAW resonators 4a and 4b arePiezoelectricOn board
Electrode array of transmitting electrodes 5a and 5b and receiving electrodes 6a and 6
b electrode array is arranged and transmitting electrodes 5a, 5b and
And the reflectors 8a, 6a, 6b at symmetrical positions outside the receiving electrodes 6a, 6b.
8b, 9a, 9b array structure is formed
And the distance between the reflectors in one SAW resonator 4a
L_c1, Effective distance in reflector δ ₁ And array pitch d₁ Against
And the distance between the reflectors in the other SAW resonator 4b
L_c2, Effective distance in reflector δ₂ And array pitch d₂ The regulation
Similar pattern with a size ratio K that gives a constant frequency difference F
And the apex temperature T between the pair of SAW resonators_Ten, T ₂₀Difference
The feature is that ΔT is suppressed to zero or minimum.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

[0016]

In the tilt sensor of the present invention having such a structure, as the electrode pattern of the SAW resonator provided on both surfaces of the piezoelectric substrate forming the cantilever, one pattern is defined as the other pattern, for example, K = Even if the inter-reflector distance L _c is changed in order to make the oscillation frequency different, by using a similar pattern with a magnification of 0.9996, two S
The composition ratio (L _c / δ) of the AW resonator can be the same, and if the composition ratio (L _c / δ) is the same, the apex temperature is also the same. Therefore, the apex temperature difference ΔT is zero or the pole. It can be a very small value.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

In the actual manufacturing process, two S
Even if the AW resonator has a similar pattern, the thickness and width of the electrodes vary during the manufacturing process, and it is difficult to make the vertex temperatures the same. Therefore, in the present invention, as the operating characteristics of the SAW resonator, the composition ratio (L) between the inter-reflector distance L _c of the pair of SAW resonators 4a and 4b and the intra-reflector effective distance δ is set.
_{When c} / δ) is changed, the peak temperature hardly changes
By paying attention to the fact that there is a point, and setting the composition ratio (L _c / δ) to a value at or near this point , even if dimensional variations occur in the shape of the electrode pattern during the manufacturing process, It is possible to manufacture a tilt sensor that minimizes the change in the peak temperature and consequently has an extremely small temperature error.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

[0019]

EXAMPLE A cantilever for a SAW tilt sensor according to the present invention
For example, a crystal substrate is used as the substrate, but FIG. 1 is a configuration diagram of an embodiment showing the electrode arrangements of the SAW resonators formed on both sides of the crystal substrate in comparison. In FIG. 1, 4a and 4b are SAW resonators, one end of which is supported by a fixed portion 2 and a weight 3 is attached to the other end of the cantilever 1 which is free as shown in FIG. Is formed on each of the surfaces on both sides of.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

FIG. 2 shows the SAW resonator used in the present invention.
And the distance between reflectors L_c And the effective distance in the reflector δ
(L_c / Δ) apex temperature T with respect to₀ Characteristics showing the relationship of
It is a figure. The characteristic diagram of FIG. 2 shows that the present inventors
In order to solve the problem of temperature drift in the tilt sensor,
A simulator that realizes the operation function of the SAW tilt sensor
Create and use this simulator to calculate the composition ratio (L_c /
δ) is changed and the peak temperature T ₀ Discovered when considering the fluctuation of
And furthertheoryThe results shown in Figure 2 were obtained
I was able to confirm that.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

At points A and B in this characteristic curve and in the vicinity thereof, it is apparent that the shift amount of the apex temperature is small with respect to the variation of the composition ratio (L _c / δ). Thus, the ratio of the distance between reflectors to the effective distance within the reflector (L _c /
By determining δ) to be a value at or near points A and B, dimensional variations such as thickness and width that occur when the electrode patterns of the SAW resonators 4a and 4b shown in FIG. 1 are manufactured. It is possible to minimize the difference ΔT between the peak temperatures T ₁₀ and T ₂₀ due to.

[Procedure Amendment 13]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

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On the other hand, the inter-reflector distance, the intra-reflector effective distance, and the electrode pitch are determined so that the composition ratio (L _c / δ) of the values at points A and B in FIG. Therefore, even if the thickness and width of the electrode pattern vary during the manufacturing process, even if the composition ratio (L _c / δ) changes at points A and B and in the vicinity thereof, it is clear that the peak temperature is so high as is clear from the characteristics of FIG. Does not shift, and the peak temperature difference ΔT due to variations in manufacturing is minimized. As a result, the temperature drift term 2a (f ₁₀ / Δf) ΔT in the equation (3) is set to an extremely small value, and the inclination angle The measurement accuracy can be improved.

[Procedure Amendment 14]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

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[0032]

As described above, according to the present invention, the two SAW resonators have similar patterns so that the peak temperatures of the two SAW resonators are the same and the temperature drift in the detection of multiple frequencies is eliminated or minimized. The measurement accuracy of the tilt angle can be improved by suppressing it. Further, by setting the composition ratio of the inter-reflector distance and the effective distance within the reflector in the electrode pattern to a value at or near the point where the variation of the vertex temperature is small, the electrode pattern generated in the manufacturing stage of the SAW sensor having a similar pattern. It is possible to minimize the apex temperature difference with respect to the variation in thickness and width and to significantly improve the yield in the manufacturing stage in which a fine similar electrode pattern is formed.

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

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[Figure 3]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Ouchi 2-16-46 Minami-Kamata, Ota-ku, Tokyo Within Tokimetsuku Co., Ltd.

Claims (2)

[Claims] 1. A cantilever made of a quartz substrate having one end fixed and the other end free and a weight attached thereto, and a pair of SAW resonators having different resonance frequencies formed on both front and back surfaces of the cantilever, respectively. A pair of SAW oscillators that positively feed back the output of the SAW resonator to oscillate a signal having a frequency (f ₁ , f ₂ ) matching the resonance frequency, and a frequency difference (F) between the oscillation signals of the pair of SAW oscillators are A mixer to detect,
In a tilt sensor that detects a tilt angle θ with respect to a vertical axis of the cantilever based on a frequency difference (F) output from the mixer, the pair of SAW resonators includes a transmitter electrode array and a SAW resonator on the quartz substrate. A structure is provided in which receiving electrode arrays are arranged and reflector arrays are formed outside the transmitting electrodes and the receiving electrodes, and a distance between reflectors (L _c1 ) in one SAW resonance,
Reflector within the effective distance ([delta] ₁₎ and reflector distance of the other SAW resonators to the array pitch _{(d 1) (L c2)} , the reflectors within the effective range ([delta] ₂₎ and the array pitch (d ₂₎ A similar pattern having a size ratio (K) that can obtain a specified frequency difference (F), and the difference (ΔT) between the apex temperatures (T ₁₀ , T ₂₀ ) between a pair of SAW resonators is suppressed to zero or minimum. Inclination sensor characterized by. 2. The tilt sensor according to claim 1, wherein the composition ratio (L _c / δ) of the inter-reflector distance (L _c ) of the pair of SAW resonators and the intra-reflector effective distance (δ). Is set to a value at or near the inflection point where the change in the apex temperature (T ₀ ) is the smallest with respect to the change in the composition ratio (L _c / δ).