Rear-view mirror device mounted in a vehicle, vehicle-mounted display device, vehicle-mounted display system

A glass plate includes a first arcuate surface at an outer circumferential edge part, the first arcuate surface facing a front surface side. A frame supports the glass plate from a rear surface side and includes a second arcuate surface in a portion toward the glass plate. A display unit is stored in a housing and outputs a display light toward the glass plate. A center C and a radius R of the second arcuate surface are made to be identical to a center C and a radius R of the first arcuate surface, respectively.

BACKGROUND

The present disclosure relates to a rear-view mirror device, a vehicle-mounted display device, and a vehicle-mounted display system mounted in a vehicle.

2. Description of the Related Art

A rear-view mirror device is provided in a vehicle at a position above the front window. A glass plate is provided on the frontmost surface of the rear-view mirror device, and the glass plate faces occupants in the vehicle. Further, an outwardly curved arcuate shape is provided at the outer circumferential edge of the glass plate (see, for example, patent document 1).

The arcuate shape at the outer circumferential edge of the glass plate is defined by the center of the arc (hereinafter, referred to as “arc center”) and the radius of the arc (hereinafter, referred to as “arc radius”). In order to maintain the arcuate shape, the thickness of the glass plate is made to be equal to or larger than the arc radius so that the larger the arc radius, the larger the thickness of the glass plate. A larger thickness of the glass plate increases the weight and increases the cost.

SUMMARY

The disclosure addresses the above-described issue, and a general purpose thereof is to provide a technology of inhibiting the thickness of the glass plate from being increased, while the arcuate shape at the outer circumferential edge of the glass plate is maintained at the same time.

A rear-view mirror device according to an embodiment of the disclosure includes: a glass plate that includes a first arcuate surface at an outer circumferential edge part, the first arcuate surface facing a front surface side; a casing that supports the glass plate from a rear surface side and includes a second arcuate surface in a portion toward the glass plate; and a reflective layer provided between the casing and the glass plate. A center and a radius of the second arcuate surface are made to be identical to a center and a radius of the first arcuate surface, respectively.

Another embodiment of the present disclosure relates to a vehicle-mounted display device. The device includes: a glass plate that includes a first arcuate surface at an outer circumferential edge part, the first arcuate surface facing a front surface side; a casing that supports the glass plate from a rear surface side and includes a second arcuate surface in a portion toward the glass plate; and a display unit stored in the casing and outputting a display light toward the glass plate. A center and a radius of the second arcuate surface are made to be identical to a center and a radius of the first arcuate surface, respectively.

Another embodiment of the present disclosure relates to a vehicle-mounted display system. The vehicle-mounted display system includes: an imaging device that captures an image; and a vehicle-mounted display device that displays the image captured by the imaging device.

The vehicle-mounted display device includes: a glass plate that includes a first arcuate surface at an outer circumferential edge part, the first arcuate surface facing the front surface side; a casing that supports the glass plate from a rear surface side and includes a second arcuate surface in a portion toward the glass plate; and a display unit stored in the casing and outputting a display light reflecting the image toward the glass plate. A center and a radius of the second arcuate surface are made to be identical to a center and a radius of the first arcuate surface, respectively.

DETAILED DESCRIPTION

A summary will be given before describing the invention in specific details. An embodiment of the disclosure relates to a vehicle-mounted display system mounted in a vehicle in place of a rear-view mirror device. In a vehicle-mounted display system, an imaging device is provided in a rear portion of the vehicle. A vehicle-mounted display device is provided in the vehicle on the upper side of the front window. The vehicle-mounted display device displays an image captured by the imaging device. As in the case of the rear-view mirror device mentioned above, the a glass plate is provided on the frontmost surface of the vehicle-mounted display device facing occupants in the vehicle. The glass plate like this could collide with the head of an occupant. Thus, “UN Regulation No. 46 Indirect Vision Devices” requires providing an arcuate shape having an arc diameter of 2.5 mm or larger at the outer circumferential edge of the glass plate. The thickness of the glass plate is made to be equal to or larger than the arc diameter. In the case of the aforementioned requirement, therefore, the thickness of the glass plate will be 2.5 mm or larger. The glass plate like this will be heavy and costs much.

The embodiment addresses the purpose of inhibiting the thickness of the glass plate from being increased while also maintaining the arcuate shape at the outer circumferential edge of the glass plate at the same time, by making the thickness of the glass plate smaller than the arc diameter and provides the casing that supports the glass plate from the rear surface side with an arcuate shape continuous with the arcuate shape provided in the glass plate. In other words, the embodiment meets the requirement of providing an arcuate shape having an arc diameter of 2.5 mm or larger not by the glass plate alone but by a combination of the glass plate and the casing. The terms “parallel” and “orthogonal” in the following description not only encompass completely parallel or orthogonal but also encompass slightly off-parallel and slightly non-orthogonal within the margin of error. The term “substantially” means identical within certain limits.

FIG. 1shows a structure of a vehicle1000. The right side ofFIG. 1represents the front side of the vehicle1000. As shown inFIG. 1, an orthogonal coordinate system including an x axis, y axis, and a z axis is defined. The x axis and y axis are orthogonal to each other. The x axis extends in the longitudinal direction of the vehicle1000, and the y axis extends in the horizontal direction of the vehicle1000. The z axis is perpendicular to the x axis and y axis and extends in the direction of height of the vehicle1000. The positive directions of the x axis, y axis, and z axis are defined in the directions of arrows inFIG. 1, and the negative directions are defined in the directions opposite to those of the arrows. The positive direction of the x axis may be referred to as “rear”, “rearward”, the negative direction of the x axis may be referred to as “front”, “frontward”, the positive direction of the y axis may be referred to as “right”, “rightward”, the negative direction of the y axis may be referred to as “left”, “leftward”, the positive direction of the z axis may be referred to as “above”, “upper side”, and the negative direction of the z axis may be referred to as “below”, “lower side”.

The imaging device200is provided in a rear portion of the vehicle1000and images a scene behind the vehicle1000. The imaging device200may be directly connected to the vehicle-mounted display device100or connected to the vehicle-mounted display device100via an Electronic Control Unit (ECU) (not shown). The imaging device200outputs the captured image to the vehicle-mounted display device100. The vehicle-mounted display device100and the imaging device200are included in the vehicle-mounted display system300.

The vehicle-mounted display device100is provided inside the vehicle1000and on the upper side of a front window400. The position where the vehicle-mounted display device100is provided is the position where the rear-view mirror device is provided in the related art. Inside the vehicle1000, a seat410is provided rearward of the vehicle-mounted display device100, and an occupant420is seated in the seat410. When the seat410is the driver's seat, the occupant420is the driver. The vehicle-mounted display device100receives an image from the imaging device200and displays the image for the occupant of the vehicle1000. Therefore, the vehicle-mounted display device100displays the image rearward. In the following description, the positive direction of the x axis, i.e., “rear”, “rearward”, may be referred to as “front surface side”, and the negative direction of the x axis, i.e., “front”, “frontward”, may be referred to as “rear surface side”.

FIGS. 2A-2Bshow an appearance of the vehicle-mounted display device100.FIG. 3is an exploded perspective view showing a structure of the vehicle-mounted display device100. The vehicle-mounted display device100includes a glass plate10, a double-sided adhesive tape30, a frame40, a housing60, and a display unit70. The frame40and the housing60are included in a casing80. The casing80may have an integrated structure. The glass plate10has a plate shape that extends on the x-z plane and includes a first surface12provided on the front surface side and a second surface14provided on the rear surface side. The detail of the shape of the glass plate10will be discussed later.

The frame40is provided on the rear surface side of the glass plate10and supports the second surface14of the glass plate from the rear surface side. The frame40includes an opposing surface42having a frame shape on the y-z pane and a side surface50extending from the outer circumferential edge of the opposing surface42toward the rear surface side. The opposing surface42represents the front surface of the frame40, and the double-sided adhesive tape30having the same shape as the opposing surface42is adhesively attached to the opposing surface42. The double-sided adhesive tape30is also adhesively attached to the second surface14of the glass plate10so that the double-sided adhesive tape30bonds the glass plate10and the frame40.

The housing60has a box shape that opens on the front surface side and includes a storage space62inside. The storage space62stores the display unit70. The display unit70is, for example, a liquid crystal display or an organic electro-luminescence display and has a box shape. A display surface72provided on the front surface side of the display unit70emits a display light presenting an image captured by the imaging device200ofFIG. 1toward the glass plate10. In a condition in which the storage space62stores the display unit70, the frame40is set in the opening of the housing60. Further, a support64for fitting the housing60inside the vehicle1000ofFIG. 1is provided on the rear surface side of the housing60.

FIG. 4is an exploded perspective view showing a structure of the vehicle-mounted display device100and is a partial cross-sectional view showing the right portion of the cross section in the y axis direction along line A-A′ ofFIG. 3. The left portion of the cross section in the y axis direction along line A-A′ and the ends of the cross section in the x axis direction also have a similar structure.FIG. 5is an enlarged cross-sectional view showing a structure of the vehicle-mounted display device100and is a cross-sectional view showing the vicinity of the right portion of the glass plate10inFIG. 3on an enlarged scale.

On the front surface side of the glass plate10, the first arcuate surface16is provided at the outer circumferential edge bounding the first surface12. The first arcuate surface16has an arcuate shape that bulges and is curved, maintaining the orientation toward the front surface side. The boundary between the first arcuate surface16and the first surface12is defined as a first boundary20. On the rear side surface side of the glass plate10, an inclined part18is provided at the outer circumferential edge part bounding the second surface14. The inclined part18is inclined upward from the second surface14toward the first arcuate surface16and is connected to the first arcuate surface16at an outer circumferential edge22.

As shown inFIG. 4, a half mirror part32is provided on the rear surface side of the second surface14. In other words, the half mirror part32is provided between the glass plate10and the frame40. The half mirror part32is a mirror that reflects a portion of incident light and transmits a portion of light such that the intensity of incident light and that of transmitted light are substantially equal. The half mirror part32has a rectangular shape that conforms to the second surface14. Instead of the half mirror part32, a highly transmissive mirror part may be used. Reference to the half mirror part32may be omitted in the following description.

The rear surface side of the half mirror part32and the opposing surface42of the frame40are adhesively attached by the double-sided adhesive tape30. Therefore, the second surface14of the glass plate10and the opposing surface42of the frame40face each other at a distance. The opposing surface42has a stepped shape in which the outer circumferential edge part is higher than the inner circumferential edge part where the double-sided adhesive tape30is provided. For example, when the double-sided adhesive tape30is provided, the distance between the second surface14and the opposing surface42in the inner circumferential edge part is 0.4 mm, and the distance between the second surface14and the opposing surface42in the outer circumferential edge part is 0.3 mm.

In the outer circumferential edge part of the opposing surface42is provided a projection46that bounds the outer circumferential edge part and, at the same time, projects toward the second surface14or the inclined part18of the glass plate10The surface to the right of the projection46is included in a second arcuate surface44, and the second arcuate surface44is connected to the side surface50. The second arcuate surface44is provided in a portion of the side surface50toward the glass plate10. The boundary between the second arcuate surface44and the side surface50is shown as a second boundary48. The second arcuate surface44has an arcuate shape continuous with the arcuate shape of the first arcuate surface16. The arcuate shape is defined by an arc center C and an arc radius R. The arc center C and the arc radius R of the first arcuate surface16and the arc center C and the arc radius R of the second arcuate surface44are substantially identical, respectively. The combination of the first arcuate surface16and the second arcuate surface44forms an arcuate shape.

By forming an arcuate shape using the combination of the first arcuate surface16and the second arcuate surface44, the length of the glass plate10in the x axis direction, i.e., the thickness, can be made smaller than the arc radius R. A description will be given of the advantage of providing the second arcuate surface44through a comparison with the case of not providing the second arcuate surface44.FIGS. 6A-6Bshow an advantage in the vehicle-mounted display device100. The figures show an appearance similar to that ofFIG. 5.FIG. 6Ashows a structure of a related-art device110in which the second arcuate surface44is not provided. The related-art device110includes the glass plate10ofFIG. 5but includes a frame140instead of the frame40. The frame140includes a projection146and a side surface150. The projection146corresponds to the projection46, and the side surface150corresponds to the side surface50. In the frame140, the second arcuate surface44is not provided in a portion of the side surface150toward the glass plate10. Therefore, the side surface150and the surface to the right of the projection146are flush.

“UN Regulation No. 46 Indirect Vision Devices” mentioned above defines a collision test using an elastic spherical object500having a diameter of 165 mm. As shown inFIG. 6A, the spherical object500caused to collide with the related-art device110comes into contact with the glass plate10and also comes into contact with the frame140. In particular, the spherical object500comes into contact with the tip of the projection146in the frame140, but the spherical object500does not easily come into contact with the side surface150even if the spherical object500is deformed because the distance between the straight side surface150and the spherical object500is large. Therefore, the load from the collision with the spherical object500is imposed on the tip of the projection146so that the tip of the projection146is easily damaged.

FIG. 6Bshows an appearance similar to that ofFIG. 5. When the spherical object500is caused to collide with the vehicle-mounted display device100, the spherical object500comes into contact with the frame40as well as coming into contact with the glass plate10. In particular, the spherical object500comes into contact with the tip of the projection46in the frame40, and the spherical object500is deformed and comes into contact with the second arcuate surface44because the distance between the second arcuate surface44and the spherical object500is small. Therefore, the load from the collision with the spherical object500spreads in the second arcuate surface44so that the tip of the projection46is not easily damaged. Reference is made back toFIG. 5.

FIGS. 7A-7Dshow various structures of the glass plate10. The figures show an appearance similar to that ofFIG. 5, but the components other than the glass plate10are omitted from the illustration. In the illustrated structures, the arc center C and the arc radius R are common, but the thickness of the glass plate10is changed. The arc radius R is made to be 2.6 mm.

FIG. 7Ashows a structure of the glass plate10having a thickness of 0.8 mm. In the case the thickness is 0.8 mm, the horizontal length from the first boundary20to the outer circumferential edge22, i.e., the horizontal length of the first arcuate surface16is 1.5 mm. The tangential line T passing through the outer circumferential edge22and the line extending from the second surface14intersect at an intersection90. The inclination of the tangential line T with respect to the second surface14at the intersection90is 36.1° as illustrated. The trajectory in which the spherical object500approaches in the aforementioned collision test using the spherical object500is denoted by a collision line D. The collision line D has an inclination of 45° with respect to the line extending from the second surface14.

FIG. 7Bshows a structure of the glass plate10having a thickness of 1.1 mm. In the case the thickness is 1.1 mm, the horizontal length of the first arcuate surface16is 1.9 mm as illustrated. The inclination of the tangential line T with respect to the second surface14at the intersection90is 46.2° as illustrated.FIG. 7Cshows a structure of the glass plate10having a thickness of 1.8 mm. In the case the thickness is 1.8 mm, the horizontal length of the first arcuate surface16is 2.4 mm as illustrated. The inclination of the tangential line T with respect to the second surface14at the intersection90is 65° as illustrated.FIG. 7Dshows a structure of the glass plate10having a thickness of 2.5 mm. In the case the thickness is 2.5 mm, the horizontal length of the first arcuate surface16is 2.6 mm as illustrated. The inclination of the tangential line T with respect to the second surface14at the intersection90is 81.2° as illustrated.

When the spherical object500is caused to collide with the glass plate10in the direction of the collision line D, the spherical object500directly comes into contact with the outer circumferential edge22and does not easily come into contact with the first arcuate surface16if the inclination of the tangential line T with respect to the second surface14is smaller than 40° at the intersection90. Therefore, the glass plate10is easily damaged if the aforementioned inclination is smaller than 45°. Thus, it is preferred that the thickness of the glass plate10be 1.1 mm or larger that makes the aforementioned inclination 45° or larger, in order to reduce the likelihood of damage to the glass plate10. Further, if the glass having a thickness larger than the arc radius R is provided with the first arcuate surface16having the arc radius R, the first arcuate surface16having the length of the arc radius R is visible when the first arcuate surface16is viewed from the front surface side. In order to give the first arcuate surface16a good appearance, it is preferred that the length of the first arcuate surface16as viewed from the front surface side approximate 2.6 mm. It is therefore preferred that the thickness of the glass plate10be 1.8 mm or larger. Further, it is preferred that the thickness of the glass plate10be as small as possible for the purpose of reducing the weight of the glass plate10. To summarize the above, the thickness of the glass plate10is made to be, for example, 1.8 mm.

FIG. 8shows physical property values of glass used in the glass plate10. Glass A represents an unreinforced glass, and glass B represents reinforced glass. In order to secure visibility on a snowy road on a clear and sunny day, the brightness of the vehicle-mounted display device100of 1100 cd/m2or larger is necessary. In consideration of power consumption and amount of heat generation, glass having a transmittance of 90% or higher is employed. In consideration of a temperature increase of +25° in an environment of 85°, the softening temperature of 110° or higher is necessary. The Vickers hardness of 500 HV or higher and the bending fracture strength of 40 MPa or higher are necessary so as not to damage the glass in the aforementioned collision test using the spherical object500. Glass A meets these conditions so that glass A is employed in the glass plate10. Glass B may be used in the glass plate10.

FIGS. 9A-9Bshow another structure of the vehicle-mounted display device100. The figures show an appearance similar to that ofFIG. 5.FIG. 9Ashows that the projection46in the structure ofFIG. 5is not included. However, the second arcuate surface44is provided in a portion of the side surface50toward the glass plate10.FIG. 9Bshows a structure in which the length of the projection46toward the front surface side is longer as compared with the structure ofFIG. 5. The projection46inFIG. 5does not reach the second surface14, but the projection46inFIG. 9Breaches the second surface14. The surface to the left of the projection46is provided along the inclined part18.

According to the embodiment, the center and the radius of the first arcuate surface in the glass plate and those of the second arcuate surface in the casing are made to be identical so that a single arcuate surface is formed by combining the first arcuate surface and the second arcuate surface. Since a single arcuate surface is formed by combining the first arcuate surface and the second arcuate surface, the thickness of the glass plate is inhibited from being increased, while the arcuate shape at the outer circumferential edge of the glass plate is maintained at the same time. Since a projection, a portion of which is included in the second arcuate surface, is provided, the gap between the glass plate and the casing is reduced. Since the gap between the glass plate and the casing is reduced, the double-sided adhesive tape is shielded from view. Since the double-sided adhesive taps is shielded from view, the appearance is improved. Provision of the projection serves as a guide in attaching the glass plate to the frame using a jig so that the assembly of the vehicle-mounted display device is facilitated. Provision of the projection gives the user holding the casing to adjust the angle a good feel.

Since the thickness of the glass plate is made to be smaller than the radius of the first arcuate surface, the thickness of the glass plate is reduced. Since the thickness of the glass plat is reduced, the weight of the glass plate is reduced. Since the thickness of the glass plate is reduced, the cost of the glass plate is reduced. Since the thickness of the glass plate is made to be 1.1 mm or larger and the radius of the first arcuate surface is made to be 2.5 mm or larger, the strength against the collision of a spherical object is increased. Since the thickness of the glass plate is made to be 1.8 mm, the requirement for strength against the collision of a spherical object and the requirement for light weight are met at the same time. Further, since the bending fracture strength is made to be 40 MPa or larger, and the Vickers hardness of the glass plate is made to be 500 HV or higher, the strength of the glass plate is increased.

One embodiment of the present disclosure is summarized below. A rear-view mirror device according to an embodiment of the disclosure includes: a glass plate that includes a first arcuate surface at an outer circumferential edge part, the first arcuate surface facing a front surface side; a casing that supports the glass plate from a rear surface side and includes a second arcuate surface in a portion toward the glass plate; and a reflective layer provided between the casing and the glass plate.

A center and a radius of the second arcuate surface are made to be identical to a center and a radius of the first arcuate surface, respectively.

According to the embodiment, the center and the radius of the first arcuate surface in the glass plate and the center and the radius of the second arcuate surface in the casing are made to be identical so that the thickness of the glass plate is inhibited from being increased while the arcuate shape at the outer circumferential edge of the glass plate is maintained at the same time.

A rear surface of the glass plate and a front surface of the casing may face each other at a distance, and the casing may further include a projection that projects toward the rear surface of the glass plate at an outer circumferential edge part of a surface of the casing.

A portion of the projection is included in the second arcuate surface. In this case, the projection, a portion of which is included in the second arcuate surface, is provided so that the gap between the glass plate and the casing is reduced.

A thickness between a front surface and a rear surface of the glass plate is smaller than the radius of the first arcuate surface. In this case, the thickness of the glass plate is made to be smaller than the radius of the first arcuate surface so that the thickness of the glass plate is reduced.

A thickness of the glass plate may be 1.1 mm or larger, and the radius of the first arcuate surface may be 2.5 mm or larger. In this case, the thickness of the glass plate is made to be 1.1 mm or larger, and the radius of the first arcuate surface is made to be 2.5 mm or larger so that the strength against the collision of a spherical object is increased.

The thickness of the glass plate may be 1.8 mm. In this case, the thickness of the glass plate is made to be 1.8 mm so that the requirement for the strength against the collision of a spherical object and the requirement for light weight are met at the same time.

A bending fracture strength of the glass plate may be 40 MPa or larger, and a Vickers hardness of the glass plate may be 500 HV or higher. In this case, the bending fracture strength is made to be 40 MPa or larger, and the Vickers hardness of the glass plate is made to be 500 HV or higher so that the strength of the glass plate is increased.

Another embodiment of the present disclosure relates to a vehicle-mounted display device. The device includes: a glass plate that includes a first arcuate surface at an outer circumferential edge part, the first arcuate surface facing a front surface side; a casing that supports the glass plate from a rear surface side and includes a second arcuate surface in a portion toward the glass plate; and a display unit stored in the casing and outputting a display light toward the glass plate. A center and a radius of the second arcuate surface are made to be identical to a center and a radius of the first arcuate surface, respectively.

According to the embodiment, the center and the radius of the first arcuate surface in the glass plate and the center and the radius of the second arcuate surface in the casing are made to be identical so that the thickness of the glass plate is inhibited from being increased while the arcuate shape at the outer circumferential edge of the glass plate is maintained at the same time.

The vehicle-mounted display device may further include a half mirror part provided between the casing and the glass plate. In this case, the half mirror part is provided so that the device is provided with the function of a half mirror.

A rear surface of the glass plate and a front surface of the casing may face each other at a distance, and the casing may further include a projection that projects toward the rear surface of the glass plate at an outer circumferential edge part of a surface of the casing. A portion of the projection is included in the second arcuate surface. In this case, the projection, a portion of which is included in the second arcuate surface, is provided so that the gap between the glass plate and the casing is reduced.

A thickness between a front surface and a rear surface of the glass plate is smaller than the radius of the first arcuate surface. In this case, the thickness of the glass plate is made to be smaller than the radius of the first arcuate surface so that the thickness of the glass plate is reduced.

A thickness of the glass plate may be 1.1 mm or larger, and the radius of the first arcuate surface may be 2.5 mm or larger. In this case, the thickness of the glass plate is made to be 1.1 mm or larger, and the radius of the first arcuate surface is made to be 2.5 mm or larger so that the strength against the collision of a spherical object is increased.

The thickness of the glass plate may be 1.8 mm. In this case, the thickness of the glass plate is made to be 1.8 mm so that the requirement for the strength against the collision of a spherical object and the requirement for light weight are met at the same time.

A bending fracture strength of the glass plate may be 40 MPa or larger, and a Vickers hardness of the glass plate may be 500 HV or higher. In this case, the bending fracture strength is made to be 40 MPa or larger, and the Vickers hardness of the glass plate is made to be 500 HV or higher so that the strength of the glass plate is increased.

Another embodiment of the present disclosure relates to a vehicle-mounted display system. The vehicle-mounted display system includes an imaging device that captures an image; and a vehicle-mounted display device that displays the image captured by the imaging device. The vehicle-mounted display device includes: a glass plate that includes a first arcuate surface at an outer circumferential edge part, the first arcuate surface facing a front surface side; a casing that supports the glass plate from a rear surface side and includes a second arcuate surface in a portion toward the glass plate; and a display unit stored in the casing and outputting a display light reflecting the image toward the glass plate. A center and a radius of the second arcuate surface are made to be identical to a center and a radius of the first arcuate surface, respectively.

According to the embodiment, the center and the radius of the first arcuate surface in the glass plate and the center and the radius of the second arcuate surface are made to be identical so that the thickness of the glass plate is inhibited from being increased while the arcuate shape at the outer circumferential edge of the glass plate is maintained at the same time.

In this embodiment, the glass plate10is included in the vehicle-mounted display device100. Alternatively, however, the glass plate10may be included in the rear-view mirror device. In the rear-view mirror device, the frame40and the housing60may be integrated as the casing80. A reflective layer is provided between the glass plate10and the casing80instead of the half mirror part32. Further, the display unit70is not included in the rear-view mirror device. According to this variation, the scope of application of the embodiment is extended.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2018-064475, filed on Mar. 29, 2018, the entire contents of which are incorporated herein by reference.