SENSOR MODULE AND CASE UNIT

A sensor module according to an embodiment of the present technology includes a sensor element, a first case, a second case, and an intermediate layer. The first case includes an opening end and accommodates therein the sensor element. The second case includes a joining surface welded to the opening end. The intermediate layer is reflective of light, and is formed along an outer peripheral edge of a region, in the opening end, in which the opening end faces the joining surface.

TECHNICAL FIELD

The present technology relates to a sensor module and a case unit that are mounted on, for example, a vehicle.

BACKGROUND ART

For example, an electronic component or an optical component, such as a rear-view camera unit for automobile, that is placed outside of a vehicle (outdoors) may be accommodated in a waterproof and dustproof case. As disclosed in, for example, Patent Literature 1, such a case includes a board, a lens barrel that holds a lens, a front case, and a rear case that is used, together with the front case, to accommodate the lens barrel and the board. The front case and the rear case are joined to each other using welding by irradiation of laser light, and this results in improving a sealing performance of the case.

CITATION LIST

Patent Literature

DISCLOSURE OF INVENTION

Technical Problem

However, with respect to an imaging device disclosed in Patent Literature 1, melted portions generated by laser light on joining surfaces of the front case and the rear case may protrude toward the outside. Such a protrusion of melted portions toward the outside is also called a resin burr. Not only does the resin burr result in a poor appearance of an outer periphery of the case that forms an appearance surface of the product, but there is a need to additionally work on removing the protruding portion. Thus, it is desirable that the occurrence of poor appearance be suppressed and the removal of a protruding portion not be performed to facilitate an operation (to improve the productivity).

In view of the circumstances described above, it is an object of the present technology to provide a sensor module and a case unit that make it possible to suppress a protrusion of melted portions of resin molded products toward the outside when the resin molded products are joined using laser welding.

Solution to Problem

In order to achieve the object described above, a sensor module according to an embodiment of the present technology includes a sensor element, a first case made of a synthetic resin, a second case made of a synthetic resin, and an intermediate layer.

The first case includes an opening end and accommodates therein the sensor element.

The second case includes a joining surface welded to the opening end.

The intermediate layer is reflective of light, and is formed along an outer peripheral edge of a region, in the opening end, in which the opening end faces the joining surface.

In the sensor module, laser light, from among irradiated light, that is incident on the intermediate layer formed along the outer peripheral edge of the region in which the opening end faces the joining surface, is reflected off the intermediate layer. This prevents an outer peripheral region of a joining surface from being melted upon performing welding using the laser light. This makes it possible to prevent a melted portion from protruding from joining surfaces of the first case and the second case toward the outside.

The intermediate layer may have a width that is less than or equal to half a width of the region.

The intermediate layer may have a thickness of 50 μm or less.

The intermediate layer may be metal or a metallic compound.

The intermediate layer may be an optical multilayer.

The intermediate layer may be reflective of laser light of a specified wavelength, the first case may be made of a synthetic resin material that has absorptive properties with respect to the laser light, and the second case may be made of a synthetic resin material that has transmissive properties with respect to the laser light.

The intermediate layer may be reflective of laser light of a specified wavelength, the second case may be made of a synthetic resin material that has absorptive properties with respect to the laser light, and the first case may be made of a synthetic resin material that has transmissive properties with respect to the laser light.

The sensor element may be an imaging device.

The sensor element may be a ranging sensor.

A case unit according to an embodiment of the present technology includes a first case, a second case, and an intermediate layer. The first case includes an opening end and accommodates therein the sensor element. The second case includes a joining surface welded to the opening end. The intermediate layer is reflective of light, and is formed along an outer peripheral edge or an inner peripheral edge of a region, in the opening end, in which the opening end faces the joining surface.

MODE(S) FOR CARRYING OUT THE INVENTION

Embodiments according to the present technology will now be described below with reference to the drawings.

(A) and (B) ofFIG.1are overall perspective views of a sensor module100according to an embodiment of the present technology.FIG.2is a longitudinal cross-sectional view of the sensor module100.FIG.3is an exploded perspective view of a primary portion of the sensor module100. An X axis, a Y axis, and a Z axis in each figure respectively represent directions of three axes that are orthogonal to each other, and the Z axis corresponds to an optical-axis direction of the sensor module100.

The sensor module100of the present embodiment is a camera module used by being mounted on a vehicle. For example, the sensor module100is arranged outside of a vehicle body (an attachment target) (not illustrated), and captures an image of a region situated ahead of a vehicle, an image of a region situated behind the vehicle, or a region on a lateral side of the vehicle depending on an attachment position.

For example, the sensor module100attached to a front portion (for example, a radiator grill) of a vehicle body captures an image of an environment ahead of the vehicle. Further, the sensor module100attached to a rear portion (for example, above a license plate) of the vehicle body captures an image of an environment behind the vehicle. Furthermore, the sensor module100attached to a side portion of the vehicle (for example, an upper portion of a pillar (an A-pillar, a B-pillar, or a pillar (a C-pillar, a D-pillar) situated in a rearmost portion of the vehicle, or a sideview mirror) captures an image of an environment in a lateral direction of the vehicle.

As illustrated inFIGS.1and2, the sensor module100includes, for example, a housing10, a sensor board20, and a barrel member60.

The housing10is a case unit that is configured by a front case11that is a first case, and a rear case12that is a second case being combined in the optical-axis direction (the Z-axis direction). Typically, the front case11and the rear case12are injection-molded bodies made of a synthetic resin material.

The front case11includes a front surface portion111that is formed substantially orthogonal to the optical-axis direction (the Z-axis direction), and a lateral surface portion112that extends toward the rear case122from a peripheral edge of the front surface portion111. In the present embodiment, the front surface portion111and the lateral surface portion112are substantially rectangular as viewed from the Z-axis direction. The front case11is hollow, and a space portion that accommodates therein, for example, the sensor board20and the barrel member60is formed in a region surrounded by the front surface portion111and the lateral surface portion112.

The front surface portion111of the front case11includes an opening113in a middle portion of the front surface portion111(refer toFIG.2). At an end of the lateral surface portion112that is situated on the side of the rear case12, the front case11includes an opening end114that is welded to the rear case12. The opening end114is formed to be substantially rectangular correspondingly to an outer shape of the front surface portion111. Note that the front surface portion111and the opening end114are not limited to being rectangular, and may be formed into another shape, such as a circular shape or a triangular shape.

The rear case12is formed into a generally rectangular plate shape that includes a bottom surface portion121that is formed substantially orthogonal to a front-rear direction, and a lateral surface portion122that extends toward the front case11from a peripheral edge of the bottom surface portion121. In a region surrounded by the bottom surface portion121and the lateral surface portion122, a rectangularly annular joining surface123that is welded to the opening end114of the front case11is formed between the bottom surface portion121and an outer peripheral surface of the lateral surface portion122. In the present embodiment, the front case11and the rear case12are integrated with each other by the joining surface123being joined to the opening end114using laser welding. This will be descried later.

The barrel member60is arranged in the front case11. The barrel member60includes a barrel601that is fitted into the opening113through a seal ring62in the optical-axis Z direction. The barrel601is a cylindrical portion that supports an imaging lens602, and protrudes forward of the front case11from the opening113.

The sensor board20is arranged in the housing10. The sensor board20includes a front board21that faces the front surface portion111of the front case11, a rear board22that faces the bottom surface portion121of the rear case12, and a spacer23that is arranged between the front board21and the rear board22.

The front board21and the rear board22are rigid double-sided circuit boards such as glass epoxy boards, and a facing distance between the boards is defined by the spacer23. The front board21and the rear board22are mechanically and electrically connected to each other through a board connector (a B-to-B connector) (not illustrated). The sensor board20is not limited to being formed of two boards that are the front board21and the rear board22, and may be formed of a single board.

An imaging device24is mounted on the front board21as a sensor element. The imaging device24is an image sensor such as a complementary metal-oxide semiconductor (CMOS) image sensor or a charge coupled device (CCD) image sensor. The front board21is joined to the barrel member601through a joining member63and a cushion member64, and the imaging device24is arranged on an optical axis of the imaging lens602. Upon joining the front case11and the rear case12, the cushion member64stably holds a facing distance between the barrel61and the imaging device24when the sensor board20is pressed toward the barrel61due to compression being performed between the sensor board20and the bottom surface portion121of the rear case12.

Further, through a flexible printed circuit40, the rear board22is electrically connected to a connector30that is provided to the bottom surface portion121of the rear case12. The connector30is used to electrically connect the sensor board20and a vehicle body. Through the connector30, power is supplied from the vehicle body to the sensor board20, and an image signal (an output signal of the imaging device24) is transmitted from the sensor board20to the vehicle body.

Note that, for example, a shield case that is used for electromagnetic noise shielding and surrounds the sensor board20, a dustproof sheet, and a heat dissipating sheet are arranged in the housing10, although this is not illustrated. One of ends of the shield case is fitted around the barrel member60, and another of the ends of the shield case is brought into elastic contact with an inner surface of the bottom surface portion121of the rear case12. Accordingly, the shield case serves as a biasing member that biases the barrel member60and the sensor board20jointed to the barrel member60toward the front case11.

The front case11and the rear case12are joined to each other using laser welding. In the present embodiment, the front case11is made of a synthetic resin material that has absorptive properties with respect to laser light of a specified wavelength. Further, the rear case12is made of a synthetic resin material that has transmissive properties with respect to the laser light.

For example, a general-purpose resin such as an acrylonitrile-styrene (AS) resin or an acrylonitrile-butadiene-styrene (ABS) resin, a polycarbonate (PC) resin, a mixture resin of ABS and PC, a polyamide (PA) resin, or a polybutylene terephthalate (PBT) resin is used as a resin material that has absorptive properties or transmissive properties with respect to laser light.

The absorptive properties or the transmissive properties with respect to laser light can be adjusted by, for example, an amount of a laser-absorptive material that is mixed with a resin. For example, carbon black can be used as the laser-absorptive material. The adjustment of an amount of the laser-absorptive material added makes it possible to adjust the laser-light absorptance (or the laser-light transmittance) discretionarily. Note that it is favorable that the same type of matrix resin be used for a resin material having absorptive properties with respect to laser light and a resin material having transmissive properties with respect to the laser light. This results in increasing an affinity between resins situated at a joining portion and in enhancing the weld strength. Further, a change in a thickness of a resin makes it possible to adjust the transmittance. When the thickness of a resin is made larger (when a resin is made thicker), this makes it possible to further decrease the transmittance of the resin. Further, when the thickness of a resin is made smaller (when a resin is made thinner), this makes it possible to further increase the transmittance of the resin.

In the present embodiment, for example, red laser light or infrared laser light of a wavelength of from 800 nm to 1100 nm is used as laser light used for welding. With respect to a resin material having transmissive properties with respect to laser light, the transmittance of the resin material with respect to the laser light is greater than or equal to 30%, and favorably greater than or equal to 40%.

FIG.4is an enlarged view of a portion A that is a portion of the opening end114of the front case11inFIG.3.FIG.5is a cross-sectional view of a joining portion of the opening end114and the joining surface123of the rear case12.FIG.6is a cross-sectional view that is similar to the cross-sectional view ofFIG.5and used to describe a process of welding the opening end114and the joining surface123by laser.

As illustrated inFIG.4, an intermediate layer50is provided to the opening end114of the front case. As illustrated inFIG.5, the intermediate layer50is formed along an outer peripheral edge of a region Rb, in the opening end114, in which the opening end114faces the joining surface123. The region Rb has a rectangularly annular shape, and the intermediate layer50is continuously formed along the outer peripheral edge of the region Rb.

In the present embodiment, a step portion115is provided between the lateral surface portion112of the front case11and an outer peripheral edge of the opening end114, and the opening end114is provided to an end surface of a rectangularly annular protrusion that protrudes by a specified amount toward the rear case12on the side of an inner periphery of the step portion115. Thus, the region Rb corresponds to the entirety of the opening end114. Note that the step portion115does not particularly have to be provided, and can be omitted as necessary.

The intermediate layer50is made of a material reflective of laser light L that is irradiated from the side of the rear case12when the opening end114and the joining surface123are welded to each other by laser, as indicated by arrows inFIG.6. The laser light L irradiated onto the region Rb, in the opening end114, in which the opening end114faces the joining surface123is partially reflected off the intermediate layer50, the laser light L being irradiated when the front case11and the rear case12are welded to each other by laser. Accordingly, heat generation caused due to the laser light L being absorbed by a region of the opening end114that is covered with the intermediate layer50, is suppressed. This results in preventing the region of the opening end114that is covered with the intermediate layer50from being melted. This makes it possible to prevent a resin component making up the region from being melted and leaking out on the side of an outer periphery of the front case11.

The intermediate layer50is a coating film that is formed in the outer peripheral edge of the opening end114. A material of the intermediate layer50is not particularly limited as long as the material is reflective of the laser light L. For example, when the laser light L is light of a wavelength of around 1000 nm, the intermediate layer50having reflectance of 90% or more can be formed using a film of metal such as gold (Au), silver (Ag), or aluminum (Al).

The material of the intermediate layer50is not limited to the metal film described above, and may be a dielectric film. The intermediate layer50having reflectance of 99% or more with respect to laser light of a wavelength of 1074 nm can be formed using high-reflective (HR) coating “RMI” of FIT Leadintex, Inc. as this type of material.

Further, the material of the intermediate layer50is not limited to the metal film and the dielectric film described above, and, for example, a metallic compound such as MgF2, or an optical multilayer (a dielectric multilayer) obtained by alternately arranging a high-refractive-index metal oxide and a constant-refractive-index metal oxide in a layered formation may be used.

A width of the intermediate layer50is not particularly limited as long as the width of the intermediate layer50is smaller than a width of the opening end114(a width of the region Rb, and the same applies to the following description). The width of the intermediate layer50can be set discretionarily according to a desired joining strength. Typically, the width of the intermediate layer50is less than or equal to half the width of the opening end114, and is favorably less than or equal to one-third the width of the opening end114. This makes it possible to effectively prevent a resin of the joining portion from being melted and leaking out on the side of the outer periphery, while securing a stable joining strength between the opening end114and the joining surface123.

A thickness of the intermediate layer50is also not particularly limited. It is favorable that the intermediate layer50be formed to have a thickness that makes it possible to obtain a stable adhesion between the opening end114and the joining surface123upon laser welding. Thus, it is more favorable that the intermediate layer50have a smaller thickness, and, for example, a thickness of50pm or less. A method for forming the intermediate layer50is also not particularly limited, and the intermediate layer50can be formed using an appropriate method for forming a thin film, such as printing, application, or vapor deposition.

Further, a concave portion of a depth that corresponds to the thickness of the intermediate layer50may be formed in advance in a portion of the opening end114that corresponds to a region in which the intermediate layer50is to be formed. In this case, the surface of the intermediate layer50can be arranged in plane with the surface of the opening end114regardless of the thickness of the intermediate layer50. In this case, a member such as a metal plate that is relatively thick can be used as the intermediate layer50. A method such as bonding or insert molding may be adopted as a method for fixing the intermediate layer50to the opening end114.

[Method for Producing Sensor Module]

When the sensor module100is produced, the barrel member60, the sensor board20, and the like are sequentially incorporated into the front case11, and then the joining surface123of the rear case12is brought into contact with the opening end of the front case11. Here, the sensor board20is electrically connected with the connector30through the flexible printed circuit40.

Subsequently, laser light L is irradiated onto the rear case12toward the opening end114in a state in which the rear case12is pressed against the front case11with a specified pressure P, as illustrated inFIG.6. The front case11is made of a resin material that has absorptive properties with respect to the laser light L, and the rear case12is made of a resin material that has transmissive properties with respect to the laser light L. Thus, the laser light L is transmitted through the rear case12to be irradiated onto the opening end114of the front case11. The laser light L is rectangularly annularly scanned along the opening end114. The laser light L may be a continuous wave or a pulsed wave.

A region, in the opening end114, that is irradiated with the laser light L generates heat due to absorption of the laser light L to be partially melted. In the present embodiment, the intermediate layer50having the configuration described above is provided to the outer peripheral edge of the opening end114. Thus, only an inner peripheral region (a region a inFIG.6) of the opening end114that is not provided with the intermediate layer50is melted. On the other hand, an outer peripheral region (a region b inFIG.6) of the opening end114that is provided with the intermediate layer50is shielded from the laser light L due to an effect of reflecting the laser light L that is provided by the intermediate layer50. This results in preventing the outer peripheral region b from being melted.

The joining surface123facing the region a is also partially melted due to heat transfer from a melted portion (the region a) of the opening end114. Thereafter, the melted portion of the region a and a melted portion of the joining surface123are cooled to be solidified, and the front case11and the rear case12are welded to each other. Since the laser light L is continuously scanned circumferentially along the rectangularly annular opening end114, welding is performed on an all-around region of the opening end114. This results in securing sealing properties of joining surfaces of the front case11and the rear case12.

In the present embodiment, the intermediate layer50is provided to the outer peripheral edge of the opening end114. This prevents a resin of the outer peripheral edge of the opening end114from being melted upon laser welding. This makes it possible to prevent a melted resin from protruding from the joining portion of the opening end114and the joining surface123toward an outer periphery of the housing10. This results in being able to prevent the occurrence of a poor appearance of the outer periphery forming an appearance surface of the housing10, and results in there being no need for an additional process of removing a protruding portion of the melted resin. Accordingly, an operation in the process of producing the sensor module100can be facilitated.

Further, according to the present embodiment, a melting amount of a melted portion in the opening end114or a melting amount of a resin can be adjusted by a location of or a formation width of the intermediate layer50. This makes it possible to properly control an amount of a protruding resin upon welding, even if, for example, there is a variation in shapes or sizes of the front case11and the rear case12, such as dimensional tolerances.

Furthermore, the present embodiment makes it possible to cause only the inner peripheral region a being included in the opening end114and not being covered with the intermediate layer50to be selectively melted even when laser light L is irradiated onto the entirety of the opening end114. This results in there being no need to accurately adjust a location, in a component, onto which laser is irradiated. This makes it possible to prevent, as intended, a melted resin from protruding even if laser light L is irradiated onto the entirety of the opening end114in a width direction of the opening end114, which is a conventional irradiation condition. Consequently, a desired welding quality can be secured without the effort to adjust a condition for equipment.

Moreover, the present embodiment makes it possible to prevent a resin of the joining portion from protruding toward the outer periphery, and thus to obtain a housing (case unit) structure that does not include a region, such as the step portion115(refer toFIGS.4to6), that is used to accommodate a melted resin. This makes it possible to increase a degree of freedom in the design of the housing10, and thus to apply the present technology to a small component for which securing a space for providing the region, such as the step portion115, that is used to accommodate a resin, is difficult.

In the embodiment described above, the intermediate layer50is provided to the opening end114of the front case11. Without being limited thereto, the intermediate layer50may be provided to the joining surface of the rear case12. In this case, effects similar to the effects provided by the embodiment described above can be obtained.

Further, the intermediate layer50is continuously formed along the outer peripheral edge of the region Rb (refer toFIG.5). However, the intermediate layer50is not limited to being formed continuously, and there may be a missing portion.

Furthermore, the technology according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure may be provided as a sensor module that is mounted on one of the types of mobile bodies such as vehicle, electric vehicle, hybrid electric vehicle, motorcycle, bicycle, personal mobility, airplane, drone, ship, robot, construction machinery, and agricultural machinery (tractor).

Further, a camera module has been described as an example of the sensor module100in the embodiment described above. However, the present technology is not limited thereto. For example, the present technology can also be adopted for a sensor module that includes, as a sensor element, a ranging sensor such as light detection and ranging (LiDAR) or a time-of-flight (ToF) sensor.

Further, in the present embodiment, the intermediate layer50is provided along the outer peripheral edge of the region Rb, in the opening end114, in which the opening end114of the front case11faces the joining surface123of the rear case12, but the configuration is not limited thereto. For example, in the case of a product in which there is a need to prevent a melted resin from protruding toward the inside of the housing, the intermediate layer50may be provided along an inner peripheral edge of the region Rb. Specifically, such a configuration is suitable for products such as a product of which a housing has a small internal volume and a product for which there is a need to protect a component accommodated in a housing from being brought into contact with a protruding portion of a melted resin of a joining portion.

Note that the present technology may also take the following configurations.

a sensor element;

a first case that includes an opening end and accommodates therein the sensor element;

a second case that includes a joining surface welded to the opening end; and

a light-reflective intermediate layer that is formed along an outer peripheral edge of a region, in the opening end, in which the opening end faces the joining surface.

(2) The sensor module according to (1), in which

the intermediate layer has a width that is less than or equal to half a width of the region.

(3) The sensor module according to (1) or (2), in whichthe intermediate layer has a thickness of 50 μm or less.

(4) The sensor module according to any one of (1) to (3), in which

the intermediate layer is metal or a metallic compound.

(5) The sensor module according to any one of (1) to (3), in which

the intermediate layer is an optical multilayer.

(6) The sensor module according to any one of (1) to (5), in which

the intermediate layer is reflective of laser light of a specified wavelength,

the first case is made of a synthetic resin material that has absorptive properties with respect to the laser light, and

the second case is made of a synthetic resin material that has transmissive properties with respect to the laser light.

(7) The sensor module according to any one of (1) to (6), in which

the intermediate layer is a coating film that is formed in an outer peripheral edge of the opening end.

(8) The sensor module according to any one of (1) to (7), in which

the sensor element is an imaging device.

(9) The sensor module according to any one of (1) to (7), in which

the sensor element is a ranging sensor.

a first case that includes an opening end;

a second case that includes an annular joining surface welded to the opening end; and

a light-reflective intermediate layer that is formed along an outer peripheral edge or an inner peripheral edge of a region, in the opening end, in which the opening end faces the joining surface.

Reference Signs List

L laser light