JP7767941B2 - Substrate and sensor device - Google Patents

Description

The present invention relates to a substrate and a sensor device.

Conventionally, torque sensors exist that detect torque based on magnetic flux that changes as the torsion bar twists. For example, the torque sensor disclosed in Patent Document 1 includes a magnetic circuit unit, a magnetic flux induction member, and a magnetic sensor. The magnetic circuit unit generates magnetic flux in response to the twist of the torsion bar. The magnetic flux induction member is magnetically coupled to the magnetic circuit unit and induces magnetic flux. The magnetic sensor includes a magnetic detection element that generates an electrical signal in response to the magnetic flux induced by the magnetic flux induction member.

The magnetic sensor has a sensor housing. A circuit board and a magnetic flux induction member are housed in the housing recess. Two magnetic detection elements are provided on the circuit board. The magnetic flux induction member, circuit board, and magnetic detection elements are all integrally covered with a waterproof covering material. The covering material is, for example, epoxy resin. This prevents the magnetic flux induction member, circuit board, and magnetic detection elements from being exposed to water.

Japanese Patent Application Laid-Open No. 2020-134440

The sensor device in Patent Document 1 has the following concerns. For example, depending on the usage environment, with long-term use, liquids such as water or chemicals may permeate the coating material and eventually reach the magnetic detection element. If liquid adheres to the magnetic detection element, there is a concern that the normal operation of the magnetic detection element may be impaired. If abnormalities occur in two magnetic detection elements at the same time, it becomes difficult to detect torque correctly.

A substrate that can solve the above problem is a substrate on which two systems of electronic components having the same function are provided. It has a coating layer that covers the electronic components and the area of the substrate surrounding the electronic components. The coating layer that covers the electronic components of the first system and the coating layer that covers the electronic components of the second system have different thicknesses.

It is possible that liquids such as water may adhere to the substrate, which may then penetrate the coating layer and reach the electronic components.
According to the above-described substrate, the thickness of the coating layer covering the electronic components of the first system is different from the thickness of the coating layer covering the electronic components of the second system. Therefore, when a liquid adhering to the substrate penetrates the coating layer, the time required to reach the electronic components of the first system is different from the time required to reach the electronic components of the second system. In other words, the liquid adhering to the substrate is prevented from reaching the electronic components of the two systems at the same time. Therefore, the occurrence of abnormalities in the electronic components of the two systems at the same time is prevented.

In the above-described substrate, the two systems of electronic components may be arranged side by side along the periphery of the substrate. The substrate may have a first region, which is the region of the substrate on the side where the two systems of electronic components are arranged, and a second region, which is the remaining region of the substrate excluding the first region. The first region may be further divided into a third region, which is the region on the side where the first system of electronic components are arranged, and a fourth region, which is the remaining region of the first region on the side where the second system of electronic components are arranged. The coating layer may have a first coating layer that covers both the third region and the fourth region, and a second coating layer that is arranged to overlap the first coating layer and covers only one of the third region and the fourth region.

With the above substrate, the thickness of the coating layer in the third region can be made thicker than the thickness of the coating layer in the fourth region, or the thickness of the coating layer in the fourth region can be made thicker than the thickness of the coating layer in the third region.

In the above substrate, the first coating layer and the second coating layer may be made of the same type of synthetic resin material.
According to the above substrate, the thickness of the coating layer covering the first system of electronic components can be made different from the thickness of the coating layer covering the second system of electronic components, using the same type of synthetic resin material.

In the above substrate, the first coating layer and the second coating layer may be made of different types of synthetic resin materials.
According to the above substrate, by using different types of synthetic resin materials, the thickness of the coating layer covering the first system of electronic components can be made different from the thickness of the coating layer covering the second system of electronic components.

In the above-described substrate, the electronic component may be a sensor configured to detect a physical quantity related to the rotational motion of a rotation shaft that is the detection target.
According to the above-described board, it is possible to prevent abnormalities from occurring in the two systems of sensors at the same time.

A sensor device that can solve the above problem includes a permanent magnet that is rotatable integrally with the rotating shaft that is the detection target, a magnetic yoke whose rotational position relative to the permanent magnet changes as the rotating shaft twists, a magnetic flux collecting ring that surrounds the magnetic yoke and collects magnetic flux from the magnetic yoke, and the above-mentioned substrate. The electronic component is a magnetic sensor that detects the magnetic flux collected by the magnetic flux collecting ring.

According to the sensor device, the same effects as those of the substrate can be obtained.
In the above sensor device, the rotation shaft may be a pinion shaft that meshes with a steering shaft that steers steered wheels of a vehicle.

The above sensor device is suitable for vehicle applications where waterproofing is required.

The circuit board and sensor device of the present invention can prevent abnormalities from occurring at the same time in two systems of electronic components mounted on the circuit board.

FIG. 1 is an exploded perspective view of an embodiment of a sensor device. 1 is a cross-sectional view of a sensor device according to an embodiment taken along an axial direction; FIG. 10 is a plan view of a comparative example of a substrate. 4 is a cross-sectional end view of the substrate taken along line 4-4 in FIG. 3. FIG. 2 is a plan view of a substrate according to an embodiment. FIG. 6 is a cross-sectional end view of the substrate taken along line 6-6 in FIG. 5. 7 is a cross-sectional end view of the substrate taken along line 7-7 in FIG. 5.

An embodiment of the sensor device will be described below.
<Overall configuration of sensor device>
As shown in Fig. 1, the sensor device 10 is provided on a rotating shaft 11 that is the detection target. The rotating shaft 11 has an input shaft 12, a torsion bar 13, and an output shaft 14. The input shaft 12 and the output shaft 14 are connected to each other via the torsion bar 13. The input shaft 12, the torsion bar 13, and the output shaft 14 are located on the same axis O. The rotating shaft 11 is, for example, a pinion shaft of a rack-and-pinion mechanism that constitutes a steering device of a vehicle. A steering wheel is connected to the pinion shaft via a steering shaft.

The sensor device 10 detects the torque applied to the rotating shaft 11 through the operation of the steering wheel. The sensor device 10 has a permanent magnet 21, a magnetic yoke 22, a substrate 23, a sensor housing 25, and a cover 26.

The permanent magnet 21 is cylindrical. The permanent magnet 21 is magnetized with alternating south and north poles in the circumferential direction. The inner circumferential surface of the permanent magnet 21 and the outer circumferential surface of the input shaft 12 fit together. The inner circumferential surface of the permanent magnet 21 is fixed to the outer circumferential surface of the input shaft 12.

The magnetic yoke 22 is cylindrical. A permanent magnet 21 is inserted inside the magnetic yoke 22. The magnetic yoke 22 has a first yoke 31, a second yoke 32, and a holder 33. The first yoke 31 and the second yoke 32 are annular members made of magnetic material. The first yoke 31 and the second yoke 32 are aligned along the axis O of the rotating shaft 11. The magnetic yoke 22 is formed by molding the first yoke 31 and the second yoke 32 with a synthetic resin material. The holder 33 is a portion of the magnetic yoke 22 made of synthetic resin material. The holder 33 maintains the positional relationship between the first yoke 31 and the second yoke 32. The magnetic yoke 22 is fixed to the output shaft 14.

The first yoke 31 has a plurality of teeth 31a. The teeth 31a are arranged at equal intervals in the circumferential direction of the first yoke 31. The second yoke 32 has a plurality of teeth 32a. The teeth 32a are arranged at equal intervals in the circumferential direction of the second yoke 32. The teeth 31a and 32a extend in opposite directions in the direction along the axis O of the rotating shaft 11. The teeth 31a and 32a are arranged alternately in the circumferential direction of the first yoke 31 and the second yoke 32. When no torsional deformation occurs in the torsion bar 13, the circumferential centers of the teeth 31a and 32a coincide with the boundary between the north and south poles of the permanent magnet 21.

The substrate 23 is a rectangular plate. The substrate 23 has a first main surface and a second main surface located opposite each other in the direction along the axis O. The substrate 23 also has three support holes 41, multiple terminal connection holes 42, a first magnetic sensor 45, and a second magnetic sensor 46. The support hole 41 is located near the center of the substrate 23. The support holes 41 are aligned in a row along the long side of the substrate 23. The terminal connection holes 42 are aligned, for example, in two rows along the first long side of the substrate 23. The first magnetic sensor 45 and the second magnetic sensor 46 are located on the first main surface of the substrate 23. The first magnetic sensor 45 and the second magnetic sensor 46 are located on the periphery of the substrate 23. The first magnetic sensor 45 and the second magnetic sensor 46 are aligned along the second long side of the substrate 23. The first magnetic sensor 45 and the second magnetic sensor 46 are identical components and have the same functions. The first magnetic sensor 45 and the second magnetic sensor 46 are used to detect the rotation angle of the rotating shaft 11 and are, for example, Hall sensors. The rotation angle of the rotating shaft 11 is a physical quantity related to the rotational motion of the rotating shaft 11. The first magnetic sensor 45 is an electronic component of the first system. The second magnetic sensor 46 is an electronic component of the second system.

The sensor housing 25 has an outer housing 25A and a cylindrical inner housing 25B. The outer housing 25A and inner housing 25B are each molded from resin. The inner housing 25B is formed integrally with the outer housing 25A by insert molding. Insert molding is a molding technique in which the inner housing 25B, which is an insert part, is installed in an open mold, and the mold is then closed for injection molding. Inside the mold, the inner housing 25B is enveloped, except for a small portion, by molten resin injected into the mold. This molten resin cools and solidifies, forming the outer housing 25A outside the inner housing 25B. The sensor housing 25 has a protruding portion that protrudes radially outward from the inner housing 25B. The rotating shaft 11 is arranged to pass axially through the sensor housing 25.

The sensor housing 25 has a cylindrical insertion hole 51, a cylindrical first accommodating chamber 52, and a second accommodating chamber 53. The insertion hole 51 and the first accommodating chamber 52 are connected to each other. The insertion hole 51 and the first accommodating chamber 52 are located on the same axis O. The inner diameter of the insertion hole 51 is slightly larger than the outer diameter of the rotating shaft 11. The input shaft 12 is inserted into the insertion hole 51 via the first accommodating chamber 52.

The inner diameter of the first accommodating chamber 52 is slightly larger than the outer diameter of the magnetic yoke 22. The inner circumferential surface of the inner housing 25B forms the inner circumferential surface of the first accommodating chamber 52. The first accommodating chamber 52 accommodates the permanent magnet 21 and magnetic yoke 22.

The second storage chamber 53 is provided in the protruding portion of the sensor housing 25. The second storage chamber 53 accommodates the circuit board 23. The second storage chamber 53 has a rectangular opening 53a. The opening 53a opens radially outward from the inner housing 25B. The opening 53a is closed by the cover 26.

Three support protrusions 54 are provided on the inner end surface of the second storage chamber 53. The support protrusions 54 are, for example, cylindrical with a step. The support protrusions 54 are lined up in a row along the long side of the opening 53a. Each support protrusion 54 corresponds to one of the support holes 41 in the base plate 23.

First ends of multiple terminals 55 protrude from the inner end surface of the second storage chamber 53. The multiple terminals 55 are arranged, for example, in two rows along the long side of the opening 53a. The first ends of the terminals 55 are located outside the support protrusion 54 in the opening direction of the opening 53a. The multiple terminals 55 correspond to multiple terminal connection holes 42 provided in the substrate 23.

A rectangular cylindrical connector fitting portion 56 protrudes from the outer surface of the end wall of the protruding portion of the sensor housing 25. The second ends of the multiple terminals 55 penetrate the end wall of the protruding portion of the sensor housing 25 and are exposed inside the connector fitting portion 56. A wiring connector (not shown) that electrically connects the terminals 55 of the board 23 to an external device is fitted into the connector fitting portion 56. The external device could be, for example, a steering device control device.

A first magnetic flux collecting ring 61 and a second magnetic flux collecting ring 62 are provided on the inner peripheral surface of the first storage chamber 52. The first magnetic flux collecting ring 61 and the second magnetic flux collecting ring 62 are integrally formed with the inner housing 25B by insert molding. The first magnetic flux collecting ring 61 and the second magnetic flux collecting ring 62 are arc-shaped plates that curve along the outer periphery of the magnetic yoke 22. The first magnetic flux collecting ring 61 and the second magnetic flux collecting ring 62 are aligned in a direction along the axis O of the rotating shaft 11. The first magnetic flux collecting ring 61 corresponds to the first yoke 31. The second magnetic flux collecting ring 62 corresponds to the second yoke 32. The first magnetic flux collecting ring 61 has two magnetic flux collecting protrusions 61a, 61b. These magnetic flux collecting protrusions 61a, 61b are exposed inside the second storage chamber 53. The second magnetic flux collecting ring 62 has two magnetic flux collecting protrusions 62a, 62b. These magnetic flux collecting protrusions 62a, 62b are exposed inside the second storage chamber 53. The magnetic flux collecting protrusions 61a and 62a of one pair face each other in the direction along the axis O. The magnetic flux collecting protrusions 61b and 62b of the other pair face each other in the direction along the axis O.

<Sensor device installation state>
As shown in FIG. 2 , the sensor device 10 is attached to a housing 15. The interior of the sensor housing 25 and the interior of the housing 15 are in communication with each other. The housing 15 rotatably supports the rotating shaft 11, which is the object to be detected. The housing 15 is, for example, a gear housing that houses a rack-and-pinion mechanism that constitutes a steering device of a vehicle. The rack-and-pinion mechanism has a steering shaft that steers the steered wheels of the vehicle and a pinion shaft that meshes with the rack teeth of the steering shaft. In this embodiment, the rotating shaft 11 is the pinion shaft. The magnetic yoke 22 attached to the rotating shaft 11 is maintained housed in a first housing chamber 52 of the sensor housing 25.

The substrate 23 is attached to the inner end surface of the second storage chamber 53. The first main surface of the substrate 23, on which the first magnetic sensor 45 and the second magnetic sensor 46 are provided, faces away from the end wall of the protruding portion of the sensor housing 25. The substrate 23 has two notches 23a. These notches 23a are provided on the side edges of the substrate 23 corresponding to the first magnetic sensor 45 and the second magnetic sensor 46. When the substrate 23 is attached to the inner end surface of the second storage chamber 53, the magnetic flux collecting protrusions 61a, 61b of the first magnetic flux collecting ring 61 remain positioned within the notches 23a of the substrate 23.

Although not shown in the figures, each support protrusion 54 provided on the inner end surface of the second accommodating chamber 53 passes through each support hole 41 in the board 23. This restricts movement of the board 23 relative to the inner end surface of the second accommodating chamber 53. Furthermore, the first end of each terminal 55 protruding from the inner end surface of the second accommodating chamber 53 passes through each terminal connection hole 42 in the board 23. The first end of each terminal 55 is joined to the board 23 by soldering. The pattern wiring of the board 23 and each terminal 55 are electrically connected.

A permanent magnet 21 is positioned inside the first yoke 31 and second yoke 32 of the magnetic yoke 22. The permanent magnet 21, first yoke 31, and second yoke 32 form a magnetic circuit. In the direction along the axis O of the rotating shaft 11, a first magnetic flux collector ring 61 is held at a position corresponding to the first yoke 31. The first magnetic flux collector ring 61 surrounds the periphery of the first yoke 31. The first magnetic flux collector ring 61 guides magnetic flux from the first yoke 31. A second magnetic flux collector ring 62 is held at a position corresponding to the second yoke 32. The second magnetic flux collector ring 62 surrounds the periphery of the second yoke 32. The second magnetic flux collector ring 62 guides magnetic flux from the second yoke 32.

The magnetic flux collecting protrusion 61a of the first magnetic flux collecting ring 61 and the magnetic flux collecting protrusion 62a of the second magnetic flux collecting ring 62 are parallel to each other. The first magnetic sensor 45 is interposed between the magnetic flux collecting protrusion 61a of the first magnetic flux collecting ring 61 and the magnetic flux collecting protrusion 62a of the second magnetic flux collecting ring 62. Although not shown in the figure, the magnetic flux collecting protrusion 61b of the first magnetic flux collecting ring 61 and the magnetic flux collecting protrusion 62b of the second magnetic flux collecting ring 62 are parallel to each other. The second magnetic sensor 46 is interposed between the magnetic flux collecting protrusion 61b of the first magnetic flux collecting ring 61 and the magnetic flux collecting protrusion 62b of the second magnetic flux collecting ring 62. The first magnetic sensor 45 and the second magnetic sensor 46 detect magnetic flux induced in the first magnetic flux collecting ring 61 and the second magnetic flux collecting ring 62.

When torque is applied to the input shaft 12 through operation of the steering wheel, the torsion bar 13 undergoes torsional deformation. A relative rotational displacement occurs between the input shaft 12 and the output shaft 14 in response to the torque applied to the input shaft 12. This changes the relative position of the permanent magnet 21 and the first yoke 31 in the rotational direction. This changes the magnetic flux induced from the permanent magnet 21 to the first magnetic flux collector ring 61 through the first yoke 31. This also changes the relative position of the permanent magnet 21 and the second yoke 32 in the rotational direction. This changes the magnetic flux induced from the permanent magnet 21 to the second magnetic flux collector ring 62 through the second yoke 32.

The first magnetic sensor 45 generates an electric signal corresponding to the magnetic flux leaking between the magnetic flux collecting protrusion 61a of the first magnetic flux collecting ring 61 and the magnetic flux collecting protrusion 62a of the second magnetic flux collecting ring 62. The second magnetic sensor 46 generates an electric signal corresponding to the magnetic flux leaking between the magnetic flux collecting protrusion 61b of the first magnetic flux collecting ring 61 and the magnetic flux collecting protrusion 62b of the second magnetic flux collecting ring 62. The electric signals generated by the first magnetic sensor 45 and the second magnetic sensor 46 change depending on the torsional deformation of the torsion bar 13, i.e., the torsion angle of the torsion bar 13. The steering device control device calculates the torque acting on the torsion bar 13 based on the electric signals generated by the first magnetic sensor 45 and the second magnetic sensor 46. Torque is a physical quantity related to the rotational motion of the rotating shaft 11.

<Comparative example of substrate>
Next, a comparative example of the substrate 23 will be described.
In case that liquid such as water or chemicals enters the inside of the second storage chamber 53 for some reason, the substrate 23 is subjected to a waterproofing treatment.

As shown in FIG. 3 , the substrate 23 has a coating layer 71. The coating layer 71 is provided on the surface of the substrate 23. The surface is the side of the substrate 23 on which the first magnetic sensor 45 and the second magnetic sensor 46 are provided. The coating layer 71 covers, for example, half of the surface of the substrate 23 on the side on which the first magnetic sensor 45 and the second magnetic sensor 46 are provided. The first magnetic sensor 45 and the second magnetic sensor 46 are covered by the coating layer 71. This prevents the liquid from adhering to the first magnetic sensor 45 and the second magnetic sensor 46, even if liquid seeps into the second storage chamber 53.

The substrate 23 of the comparative example has the following concerns.
That is, with long-term use, the liquid adhering to the coating layer 71 may permeate the coating layer 71 and eventually reach the first magnetic sensor 45 or the second magnetic sensor 46 .

As shown in Figure 4, the thickness of the coating layer 71 is uniform. Therefore, there is a risk that the liquid will reach the first magnetic sensor 45 and the second magnetic sensor 46 at the same time. In this case, there is a concern that the normal operation of the first magnetic sensor 45 and the second magnetic sensor 46 will be impaired simultaneously.

Therefore, in this embodiment, the following configuration is adopted for the substrate 23.
<Embodiment of the substrate 23>
As shown in FIG. 5 , the substrate 23 has a first region A1 and a second region A2. The first region A1 is half of the substrate 23 on the side where the first magnetic sensor 45 and the second magnetic sensor 46 are provided. The second region A2 is the remaining half of the substrate 23 on the opposite side from the first region A1. The second region A2 is provided with a support hole 41 and a terminal connection hole 42. The first region A1 is further divided into a third region A3 and a fourth region A4. The third region A3 is the half of the first region A1 on the side where the first magnetic sensor 45 is provided. The fourth region A4 is the remaining half of the first region A1 on the side where the second magnetic sensor 46 is provided.

The substrate 23 has a coating layer 81. The coating layer 81 is provided on the surface of the substrate 23. The coating layer 81 covers the surface of the first region A1 of the substrate 23. The coating layer 81 has a first coating layer 81A and a second coating layer 81B. The first coating layer 81A covers the surface of the first region A1 of the substrate 23. The first coating layer 81A has a uniform thickness. The second coating layer 81B overlaps the first coating layer 81A. The second coating layer 81B covers only the surface of the third region A3 of the substrate 23. The second coating layer 81B has a uniform thickness.

As shown in Figures 6 and 7, the thickness T1 of the coating layer 81 covering the first magnetic sensor 45 and its surrounding area is thicker than the thickness T2 of the coating layer 81 covering the second magnetic sensor 46 and its surrounding area. In other words, the coating layer 81 covering the first magnetic sensor 45 and its surrounding area and the coating layer 81 covering the second magnetic sensor 46 and its surrounding area have different thicknesses.

<Method of manufacturing substrate 23>
Next, a description will be given of a method for manufacturing the substrate 23. The substrate 23 on which the first magnetic sensor 45 and the second magnetic sensor 46 are provided is prepared in advance.

First, a coating agent is applied to the surface of the first region A1 of the substrate 23. The coating agent is, for example, a molten synthetic resin. The synthetic resin includes an epoxy resin. The molten synthetic resin cools and solidifies, forming the first coating layer 81A.

Next, a coating agent is applied only to the surface of the third region A3 of the substrate 23. The coating agent is, for example, the same synthetic resin that constitutes the first coating layer 81A. The molten synthetic resin cools and solidifies, forming the second coating layer 81B.

This completes the manufacturing of the substrate 23.
<Actions and Effects of the Present Embodiment>
This embodiment provides the following functions and effects.

(1) The thickness T1 of the coating layer 81 covering the first magnetic sensor 45 is thicker than the thickness T2 of the coating layer 81 covering the second magnetic sensor 46. Therefore, the time required for liquid adhering to the coating layer 81 to reach the first magnetic sensor 45 is longer than the time required for the liquid to reach the second magnetic sensor 46. In other words, the liquid is prevented from reaching the first magnetic sensor 45 and the second magnetic sensor 46 at the same time. Therefore, it is possible to prevent abnormalities from occurring in the first magnetic sensor 45 and the second magnetic sensor 46 at the same time.

(2) If the liquid adhering to the coating layer 81 reaches the second magnetic sensor 46 before the first magnetic sensor 45, the first magnetic sensor 45 continues to operate normally even if the normal operation of the second magnetic sensor 46 is impaired. The torque of the rotating shaft 11 can be detected based on the electrical signal generated by the first magnetic sensor 45. This improves the operational reliability of the sensor device 10.

(3) The first coating layer 81A and the second coating layer 81B are made of the same type of synthetic resin material. The coating agent is a molten synthetic resin material. Therefore, using the same type of synthetic resin material, the thickness T1 of the coating layer 81 covering the first magnetic sensor 45 and the thickness T2 of the coating layer 81 covering the second magnetic sensor 46 can be made different.

<Other embodiments>
This embodiment may be modified as follows.
The coating layer 81 may cover the entire surface of the substrate 23 .

- Different types of coating agents may be used for the first coating layer 81A and the second coating layer 81B. Both coating agents are molten synthetic resin materials. In addition to the aforementioned epoxy resin, other synthetic resin materials such as polyimide resin and fluororesin can also be used. Even in this way, by using different types of synthetic resin materials, the thickness T1 of the coating layer 81 covering the first magnetic sensor 45 and the thickness T2 of the coating layer 81 covering the second magnetic sensor 46 can be made different.

- The coating layer 81 covering the surface of the third region A3 of the substrate 23 is not limited to two layers. For example, it may be three or four layers. In this way, the thickness T1 of the coating layer 81 covering the first magnetic sensor 45 and the thickness T2 of the coating layer 81 covering the second magnetic sensor 46 can be made different.

- The thickness T2 of the coating layer 81 covering the surface of the fourth region A4 of the substrate 23 may be greater than the thickness of the coating layer 81 covering the surface of the third region A3 of the substrate 23. For example, the surface of the fourth region A4 of the substrate 23 is covered by the first coating layer 81A and the second coating layer 81B. The surface of the third region A3 of the substrate 23 is covered only by the first coating layer 81A.

- Multiple types of coating agents with different liquid permeabilities may be used. A first coating agent and a second coating agent with lower liquid permeability than the first coating agent are prepared. The first coating agent is applied, for example, to the entire surface of the first region A1 of the substrate 23, i.e., to the surfaces of both the third region A3 and the fourth region A4. The second coating agent is applied only to the surface of the third region A3 of the substrate 23. This also makes it possible to differentiate the time required for the liquid adhering to the coating layer 81 to reach the first magnetic sensor 45 and the second magnetic sensor 46.

The sensor device 10 may be a rotation angle sensor that detects the rotation angle of the rotating shaft 11. In this case, for example, a main driving gear is mounted on the outer circumferential surface of the rotating shaft 11 so as to rotate integrally therewith. Two driven gears are rotatably supported inside the second housing chamber 53. These driven gears have different numbers of teeth. A sensor that generates an electrical signal corresponding to the rotation angle of each driven gear is provided on the substrate 23. The driven gears mesh with the main driving gear through an opening provided at the boundary between the first housing chamber 52 and the second housing chamber 53. Therefore, the two driven gears rotate in conjunction with the rotation of the main driving gear. Because the two driven gears have different numbers of teeth, the rotation angles of the two driven gears relative to the rotation angle of the main driving gear are different. Therefore, the phases of the electrical signals generated by the first magnetic sensor 45 and the second magnetic sensor 46 are different from each other. The steering device control device detects the rotation angle of the rotating shaft 11 based on the electrical signals generated by the sensors. By making the thickness T1 of the coating layer 81 covering the first sensor different from the thickness T2 of the coating layer 81 covering the second sensor, the effects described in sections (1) to (3) above can be achieved.

REFERENCE SIGNS LIST 10...Sensor device 11...Rotating shaft 21...Permanent magnet 22...Magnetic yoke 23...Substrate 45...First magnetic sensor (electronic component)
46...Second magnetic sensor (electronic component)
61...First magnetic flux collecting ring 62...Second magnetic flux collecting ring 81...Coating layer 81A...First coating layer 81B...Second coating layer A1...First region A2...Second region A3...Third region A4...Fourth region

Claims (7)

A substrate on which two systems of electronic components having the same function are provided,
a coating layer covering the electronic component and an area of the substrate surrounding the electronic component;
A substrate in which the coating layer covering the electronic components of a first system and the coating layer covering the electronic components of a second system have different thicknesses. The two systems of electronic components are arranged side by side on the periphery of the substrate,
The substrate includes a first region, which is a region of the substrate on a side where the two systems of electronic components are provided;
a second region that is the remaining region of the substrate excluding the first region;
The first region further includes a third region, which is a region on the side where the electronic components of the first system are provided;
a fourth region which is the remaining region of the first region on the side where the second-system electronic components are provided,
The coating layer includes a first coating layer covering both the third region and the fourth region;
The substrate according to claim 1 , further comprising: a second coating layer disposed to overlap the first coating layer and covering only one of the third region and the fourth region. The substrate described in claim 2, wherein the first coating layer and the second coating layer are made of the same type of synthetic resin material. The substrate described in claim 2, wherein the first coating layer and the second coating layer are made of different types of synthetic resin materials. The substrate described in any one of claims 1 to 4, wherein the electronic component is a sensor configured to detect a physical quantity related to the rotational motion of a rotation shaft that is the detection target. a permanent magnet provided so as to be rotatable integrally with a rotation shaft that is the detection target;
a magnetic yoke whose rotational position relative to the permanent magnet changes in accordance with the twist of the rotation shaft;
a magnetic flux collecting ring that surrounds the magnetic yoke and collects magnetic flux from the magnetic yoke;
The substrate according to any one of claims 1 to 5,
The electronic component is a magnetic sensor that detects magnetic flux collected by the magnetic flux collecting ring. The sensor device described in claim 6, wherein the rotating shaft is a pinion shaft that meshes with a steering shaft that steers the steered wheels of a vehicle.