JP3433767B2 - Tilt detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilt detector for detecting a tilt angle corresponding to gravitational acceleration.

[0002]

2. Description of the Related Art A conventional acceleration sensor is disclosed in Japanese Patent Laid-Open No. 3-17.
As disclosed in Japanese Patent No. 6669, a thin film resistance temperature sensor for a heater is provided in a case, an electric current is passed through the thin film resistance temperature sensor for a heater to heat the thin film resistance temperature sensor for a heater, and the temperature of the heated thin film resistance temperature sensor for a heater is adjusted. If the corresponding resistance value is detected and acceleration is applied in this state, an air flow will be generated in the case, and the heat of the thin film resistance temperature sensor for the heater will be removed along with the air flow, and the resistance of the thin film resistance temperature sensor for the heater will be removed. The value changes.

Since the change in resistance value of the thin-film resistance temperature sensor for heater corresponds to the acting acceleration, it is assumed that the acceleration is detected by detecting the change in resistance value.
Further, it is possible to use the fact that the acceleration can be detected so that the inclination angle corresponding to the gravitational acceleration can be detected.

[0004]

A conventional acceleration sensor is a thin-film resistance temperature sensor for a heater which also serves as a heating element for heating a gas inside a case and a temperature sensing element for detecting a temperature change caused by the action of acceleration. Since it is used, the absolute value of the acceleration can be detected, but the direction in which the acceleration acts cannot be detected. Even if it is applied to the detection of the tilt angle corresponding to the gravitational acceleration,
There is a problem that the direction (plus or minus) of the tilt angle cannot be detected.

Further, when a conventional acceleration sensor is mounted on a vehicle and the vehicle is simultaneously subjected to acceleration in the yaw direction (horizontal left and right) and roll direction (up and down on both sides of the vehicle), the detected acceleration is yaw. There is a problem that it becomes a combined vector of the direction and the roll direction, and even if the tilt angle is detected based on this combined vector, it is completely different from the actual tilt angle.

The present invention has been made to solve such a problem, and the object thereof is to detect an inclination angle with high accuracy by detecting only gravity acceleration with high accuracy without detecting horizontal acceleration. An object is to provide a tilt detector.

[0007]

In order to solve the above-mentioned problems, an inclination detector according to the present invention is provided with a pair of heating elements and a pair of temperature sensing means arranged to face a gas flow path, and a gas flow path. Gas flow generation means for supplying a gas flow of a predetermined value or more,
A detection unit configured to include a pair of heating elements and a pair of temperature-sensitive detection units, which detects an output corresponding to gravitational acceleration,
An angle conversion means for converting the output from the detection means into a tilt angle is provided.

Further, the pair of heating elements and the pair of temperature sensing means are arranged at a predetermined distance in the gas flow direction.

Further, the detecting means is characterized by being constituted by a resistance bridge circuit composed of a pair of heating elements and a pair of resistors of the temperature sensitive detecting means.

Further, the pair of heating elements and the pair of temperature sensing means are formed on the same semiconductor substrate by using a semiconductor manufacturing process.

[0011]

The tilt detector according to the present invention is provided with a pair of heating elements and a pair of temperature sensing means, a gas flow generating means, a detecting means, and an angle converting means in the gas flow path. When the gas flow generated from the above exceeds a predetermined value, the gas flow is deflected, the thermal equilibrium of the pair of heating elements is disrupted, and the resistance values of the pair of heating elements and the pair of temperature sensing means change, so that the resistance value changes. It is possible to detect the output corresponding to the gravitational acceleration based on the detection means and to detect the tilt angle through the angle conversion means.

Further, in the inclination detector according to the present invention, the pair of heat generating elements and the pair of temperature sensitive detecting means are arranged at a predetermined distance in the direction of the gas flow, and the temperature sensitive detecting means detects the temperature change from the heat generating elements. Since a large change in resistance value can be set, high sensitivity can be achieved.

Further, the detecting means of the inclination detector according to the present invention is constituted by a resistance bridge circuit composed of the resistances of the pair of heating elements and the pair of temperature sensitive detecting means, and the resistance values of the heating elements and the temperature sensitive detecting means. Since the change is detected, a large output can be obtained and the device can be configured with high sensitivity.

Further, in the inclination detector according to the present invention, since the pair of heating elements and the pair of temperature sensing means are formed on the same semiconductor substrate by using the semiconductor manufacturing process, there is little variation in sensitivity characteristics and stability. The detector can be configured.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a main portion of a tilt detector according to the present invention, and FIG. 2 is a functional block configuration diagram of the tilt detector according to the present invention. The inclination detector 1 is a substrate bridge 2A shown in FIG. 1 and has heating elements (heat wires) 3A and 3B, and temperature-sensitive detection means (cold wires) 4A and 4B. A semiconductor substrate, a gas flow generating means for generating a gas flow Pf, a case 6 in which all the above-mentioned components are mounted, and a gas such as CFC is sealed, and a detecting means 7 shown in FIG. , Angle conversion means 10.

In FIG. 1, for the semiconductor substrate 2, for example, a silicon wafer is subjected to a semiconductor manufacturing process such as etching or vapor deposition, and a substrate bridge 2A, a gas channel 2B, heating elements 3A, 3B such as platinum or tungsten, and a sensing element. The temperature detecting means 4A and 4B are formed and closely contacted and covered with a semiconductor substrate (not shown) provided with a gas flow path. In addition, the semiconductor substrate 2 has heating elements 3A, 3B and a temperature sensing means 4A,
Pads a to h for forming connections between 4B and external circuits are formed.

The heating element 3A and the heating element 3B, and the temperature sensing means 4A and the temperature sensing means 4B are arranged facing each other on the same plane of the substrate bridge 2A. Also, the heating element 3
The A and the temperature detecting means 4A, and the heating element 3B and the temperature detecting means 4B are arranged at a predetermined distance D in the gas flow Pf direction. Note that the lower side of the substrate bridge 2A is also etched to form a gas flow path 2B, and the gas flow Pf generated from the axial fan 5 is formed by the semiconductor substrate 2 and a semiconductor substrate (not shown) at one end (left end). Flows at a uniform flow rate over the entire box-shaped gas flow path 2 </ b> B opened.

The axial fan 5 supplies a gas such as CFC enclosed in the case 6 to the gas flow passage 2B with a uniform and predetermined flow rate of gas Pf, and applies the gas flow Pf evenly to the heating elements 3A and 3B. To arrange. The gas flow Pf that has passed through the gas flow path 2B has the semiconductor substrate and the case 6 from the left end of the gas flow path 2B.
It recirculates through the space surrounded by and returns to the right end of the axial fan 5. As the gas flow generating means, a piezoelectric pump configured by utilizing the vibration of the piezoelectric element may be used instead of the axial fan 5.

In FIG. 2, the detecting means 7 is a heating element 3A,
3B and the temperature sensitive detection means 4A, 4B are provided with a resistance bridge circuit 8 formed by connecting the pads a to h, an acceleration detection part 9, and the angle conversion means 10 is provided with an inclination angle conversion part 11 and an angle storage part 12.

The resistance bridge circuit 8 includes heating elements 3A and 3B.
And the resistance of the temperature sensing means 4A, 4B (the resistance value is R1,
R2, r1, r2) is used in the series circuit of R1 and R2.
A bridge circuit is formed so that a series circuit of 2 and r1 is connected in parallel, and a current source I _O is connected between the connecting portion of R1 and r2, the connecting portion of R2 and r1, and a connecting portion of R1 and R2.
The detection output V _O is between the connection between r2 and r1. The detection output V _O is the deviation (V _X −V _Y ) between the voltage V _X with respect to the ground of the connection between R1 and R2 and the voltage V _Y with respect to the ground at the connection of r2 and r1.

When the resistance bridge circuit 8 is driven by the current source I _O , the voltage V _X , the voltage V _Y and the detection output V _O are expressed by the equation 1.

[0022]

[Equation 1]

Now, the detection output V _O of the resistance bridge circuit 8 with respect to the inclination of the inclination detector 1 will be described. Figure 1
When the tilt detector 1 is horizontal, the heating elements 3A, 3B and the temperature sensing means 4A, 4B are also horizontal, and the gas flow Pf generated by the axial fan 5 uniformly flows through the gas passage 2B. Hits 3A and 3B evenly.

Heating elements 3A and 3B, temperature sensing means 4A and 4
When B are configured with the same characteristics (resistance value and temperature coefficient) and driven by the current source I _O , the heating elements 3A and 3B generate heat at high temperatures, and the heat transferred by the gas flow Pf is detected by the temperature detecting means 4A and 4A.
B detects. Since the heat generated by the heating elements 3A and 3B is equal and the temperatures detected by the temperature sensing means 4A and 4B are also equal, the resistances R1 and R2 of the heating elements 3A and 3B are equal, and the resistances of the temperature sensing means 4A and 4B are equal. Since r1 and r2 are also equal, the detection output V _O = 0 of the resistance bridge circuit 8 of FIG. Further, the temperature sensing means 4A, 4B and the heating elements 3A, 3B are arranged at a distance D in the gas flow direction, and the temperature gradient from the heating elements 3A, 3B is appropriately set to detect the temperature sensing means 4A, 4B. Configure to increase sensitivity.

From this state, the tilt detector 1 is moved in the horizontal right and left directions, for example, with the axial fan 5 side as a fulcrum (for example,
Even if the steering operation is carried out when mounted on a vehicle), the gas flow Pf is evenly flowing over the entire gas flow path 2B, so that the gas flow Pf is not affected by the acceleration in the horizontal direction, Since 3B is hit evenly, the detection output V _O = 0 of the resistance bridge circuit 8 is maintained.

Next, when the center of the gas flow Pf is tilted in the vertical direction (for example, a rolling phenomenon when mounted on a vehicle), for example, when the heating element 3A is on the upper side, the heating element 3
Due to the convection of heat generated from A and the heating element 3B, the temperature of the heating element 3A on the upper side is higher than that of the heating element 3B on the lower side, and the resistance R1 increases and the resistance R2 decreases. Similarly, since the temperature of the temperature-sensitive detection unit 4A on the upper side rises and the temperature of the temperature-sensitive detection unit 4B on the lower side decreases, the resistance r1 increases and the resistance r2 decreases.

Further, when the flow rate of the gas flow Pf is small, the gas flow P is affected by the gravitational acceleration (G) (from the upper side to the lower side).
f is deflected downward, the temperatures of the lower heating element 3B and the temperature sensing means 4B are lower than those of the upper heating element 3A and the temperature sensing means 4A, the resistances R2 and r2 are reduced, and the resistance R is reduced.
1, r1 increases. Therefore, from Equation 1, the detection output V _O of the resistance bridge circuit 8 detects a negative value (V _O <0), and the absolute value of the detection output V _O increases as the slope increases,
It becomes maximum at an inclination angle of 90 degrees (deg.).

As the flow rate of the gas flow Pf is increased, the gas flow Pf is gradually deflected to the upper side so that the flow rate of the gas flow Pf hitting the heating element 3A on the upper side is large and the flow rate of the heating element 3B on the lower side is small, and the resistance is reduced. R1 and r1 decrease, and resistances R2 and r2 increase. This tendency becomes stronger as the gas flow Pf increases, and the gas flow Pf of a predetermined value or more (for example, 60 sccm: sec · c
At m ³ ), the detection output V _O of the resistance bridge circuit 8 becomes a positive value (V _O > 0) proportional to the gravitational acceleration (G).

FIG. 4 shows a gravitational acceleration G-detection output V _O characteristic diagram and a gravitational acceleration G-tilt angle θ characteristic diagram. The gravitational acceleration G-detection output V _O characteristic diagram in FIG. 7A shows the tendency of the detection output V _O characteristic with the gas flow Pf as a parameter. When the gas flow Pf is 0 or small, the detection output V _O is With a negative value,
It shows a non-linear characteristic that decreases with an increase in the gravitational acceleration G and saturates as G = 1 approaches. on the other hand,
When the gas flow Pf is large, the detection output V _O has a positive value and increases with an increase in the gravitational acceleration G and exhibits a linear characteristic. The inclination detector of the present invention applies this characteristic. Constitute. The gravitational acceleration G-inclination angle θ characteristic diagram in (b) shows the relationship between the gravitational acceleration G and the inclination angle θ, where θ = sin
^This is a characteristic obtained by calculating ^-1 (G).

The gas flow Pf is large (for example, Pf = 60 scc
m or more), the resistances R2 and r2 are ΔR and Δr, respectively.
If the resistances R1 and r1 increase and the resistances R1 and Δr decrease, respectively, the detection output V _O is expressed by Expression 2 from Expression 1.

[0031]

[Equation 2]

On the other hand, when the heating element 3B is on the upper side with the center of the gas flow Pf as the axis, a phenomenon opposite to that described above occurs,
The detection output V _O of the resistance bridge circuit 8 is a negative value and exhibits a linear characteristic that decreases with an increase in the gravitational acceleration G.

The acceleration detecting section 9 corresponds to the gravitational acceleration G _O corresponding to the detection output V _O detected by the resistance bridge circuit 8.
Is generated and provided to the tilt angle conversion unit 11 of the angle conversion unit 10. For the gravitational acceleration G _O , for example, the slope (1 / V _OM ) of G / V _O of the characteristic shown in FIG. 4A is stored in the acceleration detection unit 9, and the detected output V _O and the slope (1 / V _OM ) are stored. The product of V _OM ) is calculated and the gravitational acceleration G _O is output.

The inclination angle conversion unit 11 takes in the gravitational acceleration G _O and stores it in the angle storage unit 12 in advance.
_The tilt angle θ corresponding to _O is read and output. The angle storage unit 12 is composed of a memory such as a ROM and stores the preset data of the inclination angle θ corresponding to the gravitational acceleration G in FIG. 4B.

FIG. 3 shows another embodiment of the inclination detector corresponding to FIG. 3 differs from FIG. 2 in that the resistance bridge circuit 8 is driven by the voltage source V _I and the configuration of the angle conversion means 22. By driving the resistance bridge circuit 8 with the voltage source V _I , the detection output V _O of the resistance bridge circuit 8 becomes the expression 3.

[0036]

[Equation 3]

The resistors R1 and R2, the heating elements 3A and 3B forming the resistors r1 and r2, and the temperature sensing means 4A,
Since 4B is formed on the same semiconductor substrate 2, the tolerance value of each resistance value is usually large (up to about ± 30% of the nominal value). However, since the resistance deviation changes in the same direction by the same rate, the influence of the resistance deviation can be compensated by using the resistance ratio. Therefore, by using the voltage source V _I , the detection output V _O of the equation 3 can be configured not to be affected by the resistance deviation.

Further, the angle conversion means 22 has θ = sin.
^-1 (G _O ) is provided, and the gravitational acceleration G _O from the acceleration detection unit 9 is calculated to detect the tilt angle θ shown in FIG.

FIG. 5 shows the detection output characteristics of the tilt detector according to the present invention. The gas sealed in the case 6 is Freon 1
34a, 5 atm, air flow from the axial fan 5 (gas flow P
f) is used as a parameter. The detection output V _O is
When the air flow is 40 sccm or less, it shows a negative value, but 60 sc
When the value is cm or more, a positive value is shown, the detected value is large, and a value with good linearity is obtained. For example, the detection output V _O is 200 mV
In this case, the tilt angle θ of the tilt detector 1 can detect 30 degrees.

[0040]

As described above, the tilt detector according to the present invention is provided with a pair of heating elements and a pair of temperature sensitive detecting means, a gas flow generating means, a detecting means, and an angle converting means in a gas flow path. Since it is configured to detect the output corresponding to the gravitational acceleration by deflecting the gas flow in the tilt direction without detecting the horizontal acceleration, the tilt angle of the tilt corresponding to the gravitational acceleration can be determined. Can be detected.

Further, since the pair of heat generating elements and the pair of temperature sensitive detecting means are arranged at a predetermined distance in the gas flow direction, the temperature gradient from the heat generating elements to the temperature sensitive detecting means can be increased, so that the temperature sensitive detecting means can detect the temperature. The sensitivity can be increased.

Further, a resistance bridge circuit is constituted by a pair of heating elements and a pair of temperature sensing means arranged in the flow path, and the output is detected based on the resistance change of all the resistance bridges. A detector can be obtained.

Further, since the pair of heating elements and the pair of temperature sensing means are formed on the same semiconductor substrate, it is possible to obtain a tilt detector having stable sensitivity characteristics.

Therefore, it is possible to provide an inclination detector which can detect the inclination angle with high accuracy and stability.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of a tilt detector according to the present invention,

FIG. 2 is a functional block configuration diagram of a tilt detector according to the present invention.

FIG. 3 is another embodiment of the tilt detector corresponding to FIG.

[FIG. 4] Gravity acceleration G-detection output V _O characteristic diagram, gravity acceleration G-tilt angle θ characteristic diagram

FIG. 5 is a detection output characteristic of the tilt detector according to the present invention.

[Explanation of symbols]

1, 21 ... Inclination detector, 2 ... Semiconductor substrate, 2A ... Substrate bridge, 2B ... Gas channel, 3A, 3B ... Heating element (R1,
R2), 4A, 4B ... Temperature sensing means (r1, r2), 5
... axial fan, 6 ... case, 7 ... detection means, 8 ... resistance bridge circuit, 9 ... acceleration detection section, 10, 22 ... angle conversion means, 11 ... tilt angle conversion section, 12 ... angle storage section, ah.
... Pad, G, G _O ... Gravity acceleration, Pf ... Gas flow, V _O ...
Detection output, θ ... Tilt angle.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-176669 (JP, A) JP-A-6-300563 (JP, A) Actually open 3-109059 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) G01C 9/00-9/36 G01B ^7/ 00-7/34 G01B 21/00-21/32 G01P 15/00-15/16

Claims (4)

(57) [Claims] 1. A pair of heating elements and a pair of temperature sensing means arranged to face the gas flow path, a gas flow generation means for supplying a gas flow of a predetermined value or more to the gas flow path, and the pair of Comprised of a heating element and the pair of temperature sensing means,
An inclination detector comprising: detection means for detecting an output corresponding to gravitational acceleration; and angle conversion means for converting an output from the detection means into an inclination angle. 2. The tilt detector according to claim 1, wherein the pair of heating elements and the pair of temperature sensing means are arranged at a predetermined distance in the direction of the gas flow. 3. The tilt detector according to claim 1, wherein the detection means is composed of a resistance bridge circuit including resistances of the pair of heating elements and the pair of temperature sensitive detection means. 4. The tilt detector according to claim 1, wherein the pair of heating elements and the pair of temperature sensing means are formed on the same semiconductor substrate by using a semiconductor manufacturing process.