Multiple-axis gas flow type angular velocity sensor

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multiple-axis gas flow type angular velocity sensor which detects angular velocity in a plurality of directions such as a yaw direction and a pitch direction, and in particular relates to a multiple-axis gas flow type angular velocity sensor which is constructed using a semiconductor production process.

2. Description of the Related Art

Known conventional multiple-axis gas flow type angular velocity sensors include those in which thermosensitive resistor elements are constructed from thin platinum or tungsten wires, a plurality of thermosensitive resistor elements are attached in pairs to supports provided in a case and are located such that angular velocity in the desired directions is detected information on such instruction may be referred to in Japanese Publication S61-180147.

Conventional multiple-axis gas rate sensors have a construction in which discrete component thermosensitive resistor elements, consisting of thin platinum or tungsten wires, are attached to supports, and there are therefore problems relating to positional accuracy involving the location of the paired thermosensitive resistor elements, for example the distance to the central axis of the gas flow and the direction (perpendicular) with respect to the central axis, and there are also problems due to the time required for adjustment operations in order to maintain positional accuracy.

Further, in conventional multiple-axis gas flow type angular velocity sensors, the thermosensitive resistor elements, the supports and the case are constructed from discrete components, and there are problems in that it is necessary to select components to unify the pairing properties and characteristics of individual thermosensitive resistor elements (resistance and temperature characteristics).

SUMMARY OF THE INVENTION

In the present invention, a pair of thermosensitive resistor elements, or one or more thermosensitive resistor elements, and a space which forms a gas passage are formed on a semiconductor substrate using a photo engraving process, which is a semiconductor production process.

By laminating a plurality of these semiconductor substrates, a sensor case which has a sealed space which forms a gas passage is formed, and a multiple-axis gas flow type angular velocity sensor is provided, in which a plurality of pairs of thermosensitive resistor elements are mutually perpendicular, by the thermosensitive resistor elements being located mutually perpendicular to and symmetrical about the central axis of the gas flow.

In the multiple-axis gas flow type angular velocity sensor according to the present invention, constructed as described above, thermosensitive resistor elements are formed on semiconductor substrates such as silicon using a photo engraving process, which is a process for producing semiconductors, and thermosensitive resistor elements with good pairing properties are located accurately in desired positions, and it is therefore possible to detect angular velocity acting in any direction accurately and stably.

Further, in the multiple-axis gas flow type angular velocity sensor according to the present invention it is possible to construct a sensor including a gas passage and a case by laminating a plurality of semiconductor substrates formed by micro-scale processes, and miniaturization and cost-effectiveness of the sensor can therefore be planned.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a structure of a multiple-axis gas flow type angular velocity sensor according to the present invention.

FIG. 2 is a exploded perspective view of the structure of a multiple-axis gas flow type angular velocity sensor according to the present invention.

FIG. 3 is a circuit diagram showing components for detecting angular velocity in the yaw direction corresponding to FIG. 1.

FIG. 4 is a circuit diagram showing components for detecting angular velocity in the pitch direction corresponding to FIG. 1.

FIG. 5 is a perspective view of a structure of an alternative embodiment of a multiple-axis (double-axis) gas flow type angular velocity sensor according to the present invention.

FIG. 6 is a circuit diagram showing components for detecting angular velocity in the yaw direction corresponding to FIG. 5.

FIG. 7 is a circuit diagram showing components for detecting angular velocity in the pitch direction corresponding to FIG. 5.

FIG. 8 is a conceptual diagram of a multiple-axis gas flow type angular velocity sensor with three axes, according to the present invention.

DETAILED DESCRIPTION

A preferred embodiment of the present invention will now be described with reference to the attached drawings.

FIG. 1 is an external perspective of a multiple-axis gas flow type angular velocity sensor according to the present invention, and FIG. 2 is an exploded perspective view of this multiple-axis gas flow type angular velocity sensor according to the present invention.

In FIG. 1, the multiple-axis gas flow type angular velocity sensor 1 indicates an embodiment of a double-axis gas flow type angular velocity sensor, in which thermosensitive resistor elements H_W-l, H_W-R, H_W-U, and H_W-D, a gas flow inlet 6 through which gas G_S is input, a gas passage through which a gas jet F_R flows, and upper and lower cases, for example, are formed as semiconductor components, using a semiconductor production process such as a photo engraving process, on a plurality of semiconductor substrates such as silicon, after which the sensor is constructed by laminating the plurality of semiconductor components using batch processing.

One pair of thermosensitive resistor elements H_W-L and H_W-R are located facing each other in a left-right direction (X axis) perpendicular to the central axis of the gas flow (Y axis), and detect the angular velocity acting on the multiple-axis gas flow type angular velocity sensor 1 with the Z axis as the axis of rotation.

Further, a pair of thermosensitive resistor elements H_W-U and H_W-D are located facing each other an up-down direction (Z axis) which is perpendicular to both the central axis of the gas flow (Y axis) and the perpendicular direction (X axis), and detect the angular velocity acting on the multiple-axis gas flow type angular velocity sensor 1 with the X axis as the axis of rotation.

Considering a situation in which the multiple-axis gas flow type angular velocity sensor 1 is mounted on a moving body (for example a vehicle), running in the Y-axis direction, the thermosensitive resistor elements H_W-L and H_W-R detect angular velocity in the horizontal (yaw) direction, while the thermosensitive resistor elements H_W-U and H_W-D detect angular velocity in the direction in which the front and rear of the moving body (for example a vehicle) rise and fall (pitch).

The gas jet F_Y flows in the form of a parabolic body of rotation with the Y axis of the gas passage of the multiple-axis gas flow type angular velocity sensor 1 as the axis of symmetry, and therefore the gas flow acts simultaneously on the thermosensitive resistor elements H_W-L and H_W-R, and the thermosensitive resistor elements H_W-U and H_W-D, and therefore angular velocity in the yaw direction and the pitch direction are detected simultaneously.

For example, if an angular velocity acts in the yaw direction, then the Coriolis force acts and the gas flow is deflected, the balance of the amount of gas coming into contact with the thermosensitive resistor elements H_W-L and H_W-R is disturbed, the resistances of the thermosensitive resistor elements H_W-L and H_W-R change, and it is possible to detect the magnitude and direction of the angular velocity in the yaw direction.

However, if an angular velocity acts only in the yaw direction, the amount of gas coming into contact with the thermosensitive resistor elements H_W-U and H_W-D are maintained, and no angular velocity in the pitch direction is detected.

Further, if an angular velocity acts only in the pitch direction, the Coriolis force acts on the gas flow in the pitch direction, causing the gas flow to be deflected, the balance of the amount of gas coming into contact with the thermosensitive resistor elements H_W-U and H_W-D is disturbed, the resistances of the thermosensitive resistor elements H_W-U and H_W-D change, and it is possible to detect the magnitude and direction of angular velocity in the pitch direction, but no angular velocity in the yaw direction is detected.

In this way it is possible to construct a double-axis angular velocity rate sensor in which the detection of the yaw direction and pitch direction are independent from each other.

It should be noted that if an angular velocity acts simultaneously in the yaw direction and the pitch direction, the gas flows in the yaw direction and the pitch direction are deflected simultaneously, and it is therefore possible to detect the magnitude and direction of the angular velocity in the yaw direction and the pitch direction simultaneously.

The construction of a multiple-axis (double-axis) gas flow type angular velocity sensor will now be described.

FIG. 2 is an exploded perspective view of a multiple-axis gas flow type angular velocity sensor according to the present invention.

In FIG. 2, the multiple-axis gas flow type angular velocity sensor i consists of semiconductor substrate 2 through semiconductor substrate 5.

The semiconductor substrate 2 is formed, using a semiconductor production process such as a photo engraving process, with a gas flow inlet in the up/down direction of the substrate and a cover indentation 7 which has a space which is a specified width from the lower surface of the substrate, and it constitutes an upper cover of the multiple-axis gas flow type angular velocity sensor 1.

A bridge 8 is formed in the semiconductor substrate 3 using a semiconductor production process in which vacuum evaporation and a plurality of etching processes are repeated, and the semiconductor substrate 3 is provided with a thermosensitive resistor element H_W-U, which is formed by etching and patterning after platinum or tungsten has been vacuum evaporated onto a prescribed position on the bridge 8, and with leads and external connection pads which are formed by patterning a semiconductor material.

It should be noted that the thermosensitive resistor element H_W-U and a thermosensitive resistor element H_W-D which is formed on the semiconductor substrate 5 constitute a pair of sensors, and these are positioned accurately in advance using a production mask such that they detect angular velocity in the pitch direction.

Further, a space underneath the bridge, and a through-passage 9, constituting part of the gas passage, are formed in the semiconductor substrate 3 by etching.

The semiconductor substrate 4 is formed with a space underneath the bridge, and with a through-passage 11 using the same processes as for the semiconductor substrate 3, except that a pair of thermosensitive elements H_W-L and H_W-R are formed in prescribed positions on the bridge 10.

It should be noted that the pair of thermosensitive resistor elements H_W-L and H_W-R are positioned accurately in advance using a production mask such that they detect angular velocity in the yaw direction, in the same way as with the thermosensitive resistor element H_W-U formed on the semiconducor substrate 3.

The semiconductor substrate 5 is formed with a bridge 12 and the thermosensitive resistor element H_W-D, in exactly the same way as the semiconductor substrate 3.

Further, a space enclosed by a gas passage floor 13 is formed by etching, thereby constructing the lower cover of the multiple-axis (double-axis) gas flow type angular velocity sensor 1.

After the semiconductor substrate 2 through semiconductor substrate 5 have been formed by means of a semiconductor production process, the semiconductor substrate 2 through semiconductor substrate 5 are laminated in one direction to form the multiple-axis (double-axis) gas flow type angular velocity sensor 1.

In this way it is possible to construct the multiple-axis (double-axis) gas flow type angular velocity sensor I with good positional accuracy by accurately setting the positions of the thermosensitive resistor elements H_W-L, H_W-R, H_W-U and H_W-D using production masks, and forming them using a semiconductor production process such as vacuum evaporation and etching.

Further, it is possible to form the pair of thermosensitive resistor elements H_W-L and H_W-R, and the pair of thermosensitive resistor elements H_W-U and H_W-D with highly accurate respective resistance ratios.

FIG. 3 shows a circuit diagram for detecting angular velocity in the yaw direction and FIG. 4 shows a circuit diagram for detecting angular velocity in the pitch direction, corresponding to FIG. 1.

The circuit in FIG. 3 has a construction in which thermosensitive resistor elements H_W-L (resistor R_L) and H_W-R (resistor R_R), and reference resistors R_F1 and R_F2 constitute a resistor bridge circuit 15, and after obtaining direct current voltage outputs V_Z1 and V_Z2 by driving the resistor bridge circuit using a supply (constant current supply I_o), a detected angular velocity output V₀₁, corresponding to the difference (V_Z1 -V_Z2) is obtained by feeding the outputs V_Z1 and V_Z2 to a comparator such as a differential amplifier 16.

If the reference resistors R_F1 and R_F2 are set to the same value, then the detected angular velocity output V₀₁ which is obtained is proportional to the resistance difference (R_R -R_L), and it is possible to detect angular velocity acting in the yaw direction.

It should be noted that the magnitude of the angular velocity is obtained from the level of the detected output V₀₁, and the direction of the angular velocity is obtained from the sign of the detected output V₀₁.

In the same way, in FIG. 4, a resistor bridge circuit 18 is constituted by thermosensitive resistor elements H_W-U (resistor R_U) and H_W-D (resistor R_D), and reference resistors R_F3 and R_F4 (R_F3 =R_F4) and therefore a detected angular velocity output V₀₂ corresponding to the difference between the direct current voltage outputs (V_X1 -V_X2) (corresponding to the resistance difference R_U --R_D) is obtained from a differential amplifier 19, and it is possible to detect angular velocity acting in the pitch direction.

FIG. 5 is a perspective view of an alternative embodiment of a multiple-axis (double-axis) gas flow type angular velocity sensor according to the present invention.

In FIG. 5, the construction is different from FIG. 1 in that the multiple-axis (double-axis) gas flow type angular velocity sensor 20 is provided with two bridges with three thermosensitive resistor elements on each of the bridges.

Thermosensitive resistor elements H_W-R1, H_W-U and H_W-L1 are formed on one of the bridges, and thermosensitive resistor elements H_W-R2, H_W-D and H_W-L2 are formed on the other bridge, thereby forming the sensor, and it is possible to eliminate one of the semiconductor substrates shown in FIG. 2 (for example either the semiconductor substrate 3 or 4).

The angular velocity in the yaw direction is detected from a combination of the thermosensitive resistor elements H_W-R1 and H_W-R2 (corresponding to H_W-R in FIG. 2), and H_W-L1 and H_W-L2 (corresponding to H_W-L in FIG. 2), and angular velocity in the pitch direction is detected from a combination of the thermosensitive resistor elements H_W-U and H_W-D (as in FIG. 2).

FIG. 6 shows a circuit diagram for detecting angular velocity in the yaw direction and FIG. 7 shows a circuit diagram for detecting angular velocity in the pitch direction, corresponding to FIG. 5.

In FIG. 6, thermosensitive resistor elements H_W-L1 (resistor R_L1) and H_W-L2 (resistor R_L2), thermosensitive resistor elements H_W-R1 (resistor R_R1) and H_W-R2 (resistor R_R2), and reference resistors R_F1 and R_F2 respectively form the sides of a resistor bridge circuit 22.

A detected angular velocity output V_0a corresponding to the difference between the direct current voltage outputs (V_Za -V_Zb) (corresponding to the combined resistance difference R_R1 +R_R2 -R_L1 -R_L2) is obtained from a differential amplifier 23, and it is possible to detect angular velocity acting in the yaw direction.

FIG. 7 illustrates a resistor bridge circuit 25 which has the same construction as resistor bridge circuit 18 of FIG. 4 which has already been described, and therefore its description will be omitted.

FIG. 8 shows a conceptual diagram of a multiple-axis gas flow type angular velocity sensor with three axes, according to the present invention.

In FIG. 8, a gas passage 34 in the X-axis direction is provided on a semiconductor substrate 31 in a multiple-axis gas flow type angular velocity sensor 30, in addition to the gas passage 33 in the Y-axis direction, which has already been described.

In the gas passage 33 in the Y-axis direction there are provided, as described with respect to FIG. 1, a pair of thermosensitive resistor elements Y₁ and Y₂ for detecting angular velocity in the yaw direction, and a pair of thermosensitive resistor elements P₁ and P₂ for detecting angular velocity in the pitch direction. In the gas passage 34 in the X-axis direction there is provided a pair of thermosensitive resistor elements R₀₁ and R₀₂, facing each other in the Z-axis direction, for detecting angular velocity in the roll direction about the Y-axis.

By arranging that gas jets F_Y and F_X be supplied simultaneously from a gas flow inlet 32 to the gas passage 33 in the Y-axis direction and the gas passage 34 in the X-axis direction it is possible to detect simultaneously and independently angular velocities acting in the yaw direction, the pitch direction and the roll direction.

In the present invention, as described above in detail with reference to embodiments, thermosensitive resistor elements are formed on semiconductor substrates such as silicon using a photo engraving process, which is a process for producing semiconductors, and thermosensitive resistor elements with good pairing properties are located accurately in desired positions, and it is therefore possible to provide a multiple-axis gas flow type angular velocity sensor which accurately and stably detects angular velocity acting in any direction.

Further, since the present invention can be constructed as a sensor including gas passages and a case by laminating a plurality of semiconductor substrates which are formed using a photo engraving process, it is possible to provide a multiple-axis gas flow type angulalr velocity sensor in which size-reduction and cost effectiveness of the sensor are achieved.