Mounting apparatus for a rearview mirror unit

Abstract

The present invention relates to mounting apparatus 1 for mounting a rearview mirror unit 3 in a vehicle (5, figure 1). The mounting apparatus includes a support arm 43; and a ball 45 disposed at an e

Description

TECHNICAL FIELD The present disclosure relates to a mounting apparatus for a rearview mirror unit. Aspects of the invention relate to a rearview mirror assembly and a vehicle. BACKGROUND It is known to provide a vehicle with a rearview mirror unit to facilitate viewing a region behind the vehicle. The rearview mirror unit may comprise a reflective surface or an electronic display. A mounting apparatus is provided to mount the rearview mirror unit, for example to a front windshield (windscreen) or a roof of the vehicle. The orientation of the rearview mirror unit can be adjusted within an operating range. For example, a ball and socket joint may be provided to enable the rearview mirror unit to be rotated about one or more axis. In the event of a collision, an occupant may come into contact with the rearview mirror unit. It would be advantageous if the rearview mirror unit absorbed energy during the collision. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a mounting apparatus, a rearview mirror assembly and a vehicle as claimed in the appended claims. According to an aspect of the present invention there is provided a mounting apparatus for mounting a rearview mirror unit in a vehicle; the mounting apparatus comprising: a support arm; a ball disposed at an end of the support arm, the ball comprising a part-spherical surface configured to engage with a cup provided in the rearview mirror unit to enable a rotational movement of the rearview mirror unit about at least one axis under a first loading condition; and a transition section disposed between the part-spherical surface of the ball and the support arm, the transition section having at least one part-conical surface configured to engage the cup provided in the rearview mirror unit to constrain the rotational movement of the rearview mirror unit about the at least one axis under the first loading condition and to enable further rotational movement of the rearview mirror unit about the at least one axis under a second loading condition, wherein the second loading condition is greater than the first loading condition. At least in certain embodiments, the mounting apparatus may provide improved energy attenuation in the event of a collision. The deflection of the rearview mirror unit under the first and second load conditions may help to dissipate the collision energy. This may provide improved safety for occupants of the vehicle. The part-spherical surface enables rotational movement of the rearview mirror unit under the first loading condition. The rearview mirror unit may be configured in the desired orientation by application of the first loading condition. The at least one part-conical surface is configured to engage the cup provided in the rearview mirror unit to limit an extent of the rotational movement of the rearview mirror unit under the first loading condition. In use, the mounting apparatus can be rotated about the at least one axis under the first loading condition until the at least one part-conical surface engages the cup provided in the rearview mirror unit. By way of example, the at least one part-conical surface may engage an entry portion of the cup. The engagement of the cup by the at least one part-conical surface may prevent or restrict further rotational movement of the rearview mirror unit about the at least one axis under the first loading condition. The at least one part-conical surface may form an intermediate stop to constrain rotational movement of the rearview mirror unit under the first loading condition. Further rotational movement of the rearview mirror unit can be achieved under the second loading condition. The second loading condition may displace a portion of the at least one part-conical surface into the cup. Under the second loading condition, the rearview mirror unit can rotate beyond the constraints introduced under the first loading condition. The rearview mirror unit may undergo a larger range of rotational movement under the second loading condition. The first loading condition may comprise the application of a first force. The second loading condition may comprise the application of a second force. The second force may be greater than the first force. The first loading condition may correspond to normal (typical) operating conditions. The first loading condition may correspond to a first force applied by a user to adjust the orientation of the rearview mirror unit. At least in certain embodiments, the ball cooperates with the cup to hold the rearview mirror unit when the first loading condition is removed. The rearview mirror unit may be retained in a desired orientation. The second loading condition may correspond to abnormal (atypical) operating conditions. The second loading condition may correspond to a second force applied during an impact or a collision. The part-spherical surface of the ball comprises a geometric centre. The rearview mirror unit is rotatable about the geometric centre of the part-spherical surface of the ball. The ball is described herein with reference to a longitudinal axis, a transverse axis and a vertical axis. Each of the longitudinal axis, the transverse axis and the vertical axis extend through the geometric centre of the part-spherical surface. The angular rotation of the rearview mirror unit is described herein relative to a reference plane extending through the geometric centre of the part-spherical surface. The transverse axis and the vertical axis are disposed in the reference plane. The at least one part-conical surface of the transition section comprises a central longitudinal axis. At least in certain embodiments, the central longitudinal axis of the at least one part-conical surface is coincident with the longitudinal axis of the ball. The reference plane may extend perpendicular to the central longitudinal axis of the transition section. As described herein, the rearview mirror unit is rotatable about at least one axis. The at least one axis may comprise at least one of a longitudinal axis, a transverse axis and a vertical axis. The at least one part-conical surface of the transition section may be configured to engage the cup to constrain the rotational movement of the rearview mirror unit about one or more of the at least one axis under the first loading condition and to enable further rotational movement of the rearview mirror unit about said one or more of the at least one axis under a second loading condition. The one or more of the at least one axis may comprise or consist of the transverse axis and / or the vertical axis. At least in certain embodiments, the rotation about the longitudinal axis may be unconstrained. Under the first loading condition, the part-spherical surface of the mounting apparatus may enable the rotational movement of the rearview mirror unit about one or more of the following: the longitudinal axis; the transverse axis and the vertical axis. At least in certain embodiments, the rotational movement is enabled, under the first loading condition, about each of the longitudinal axis, the transverse axis and the vertical axis. Under the second loading condition, the at least one part-conical surface of the mounting apparatus may constrain the rotational movement of the rearview mirror unit about one or more of the following: the longitudinal axis; the transverse axis and the vertical axis. At least in certain embodiments, the rotational movement is constrained about one or more of the longitudinal axis, the transverse axis and the vertical axis under the second loading condition. At least in certain embodiments, the rotational movement, under the second loading condition, may be constrained about one or more of the transverse axis and the vertical axis under. The rotational movement, under the second loading condition, may be unconstrained about at least one of the longitudinal axis, the transverse axis and the vertical axis. For example, the rotational movement about the longitudinal axis may be unconstrained the second loading condition. The transition section may be configured so as not to constrain the rotational movement of the rearview mirror unit about one or more axis. Thus, rotation of the rearview mirror unit may be unconstrained about one or more axis. For example, the transition section may be configured so as not to constrain the rotational movement of the rearview mirror unit about the longitudinal axis. The transition section may have a circular profile in a plane extending perpendicular to the longitudinal axis. The at least one part-conical surface may be configured to engage the cup and generate an opposing force to impede or resist the continued rotational movement of the rearview mirror unit about the at least one axis. The opposing force may oppose the force applied under the second loading condition. The opposing force may thereby resist the rotation of the rearview mirror unit. The at least one part-conical surface may be profiled such that the opposing force increases as rotation of the rearview mirror unit about the at least one axis continues. The opposing force may increase progressively as the angular rotation of the rearview mirror unit continues about the at least one axis. The opposing force may provide increased resistance to the rotational movement of the rearview mirror. Consequently, the force required to rotate the rearview mirror unit increases. The opposing force may increase in direct proportion to a rotational angle of the rearview mirror unit about the at least one axis. The mounting apparatus may enable rotation of the rearview mirror unit within a first angular range under the first loading condition. The first angular range may comprise or consist of one or more of a first pitch rotation (about the horizontal axis), and a first yaw rotation (about the vertical axis). The mounting apparatus may enable rotation of the rearview mirror unit within a second angular range under the second loading condition. The second angular range may comprise or consist of one or more of a second pitch rotation (about the horizontal axis), and a second yaw rotation (about the vertical axis). The first and second angular ranges maybe defined with respect to the reference plane described herein. The first and second angular ranges may be separate from each other, i.e., non-overlapping. The first angular range may comprise a first lower limit and a first upper limit. The first lower limit may be zero degrees (0°). The first upper limit may be a positive value or a negative value (depending on a direction of rotation). The second angular range may comprise a second lower limit and a second upper limit. Each of the second lower limit and the second upper limit may be a positive value or a negative value (depending on a direction of rotation). The first upper limit may have a magnitude which is less than or equal to a magnitude of the second lower limit. The first upper limit may be one of the following: ±30°, ±40° or ±50°. The second lower limit may be one of the following: ±30°, ±40° or ±50°. The second upper limit may be one or more of the following: ±50°, ±60° or ±70°. The mounting apparatus may enable rotation of the rearview mirror unit within the first angular range under the first loading condition. When rotating in the first angular range, the cup is clear of (i.e., spaced apart from) the transition section. When rotating at angles larger than the first angular range, the cup engages the transition section. The rearview mirror unit is rotatable at angles greater than the first angular range under the second loading condition. The rotation of the rearview mirror unit to angles greater than the first angular range are exceptional or atypical. For example, the rotation of the rearview mirror unit beyond the first angular range corresponds to a scenario in which an impact or collision force is applied to the rearview mirror unit. By resisting rotation of the rearview mirror beyond the first angular range, the transition section may help to dissipate the impact energy. In use, a first force may be required to rotate the rearview mirror unit within the first angular range. The first force may be at least substantially constant within the first angular range. In other words, the first force may not change with the angular orientation of the rearview mirror in the first angular range. The first angular range may correspond to a working range of movement for the rearview mirror. The first angular range may be defined by an extent of the part-spherical surface of the ball. The first upper limit of the first angular range may correspond to a rotational angle of the rearview mirror unit when the transition section engages the cup. When rotating in the first angular range, the cup provided on the rearview mirror unit may be spaced apart from the transition section. The mounting apparatus may enable rotation of the rearview mirror unit within the second angular range under the second loading condition. The second angular range may be greater than the first angular range. When rotating in the second angular range, the cup engages the transition section. The rotation of the rearview mirror unit in the second angular range is exceptional or atypical. For example, the rotation of the rearview mirror unit in the second angular range corresponds to a scenario in which an impact or collision force is applied to the rearview mirror unit. By resisting rotation of the rearview mirror beyond the first angular range, the transition section may help to dissipate the impact energy. The second angular range may correspond to an angular extent of the at least one part-conical surface. The angular extent may be defined with respect to the geometric centre of the part-spherical surface of the ball. The angular extent may, for example, be greater than or equal to one of the following: 10°, 20° or 30°. The second angular range may, for example, comprise one or more of the following: 30° to 40°; 40° to 50°; and 50° to 60° relative to the reference plane described herein. The second upper limit of the second angular range may be determined by the support arm. When the rearview mirror unit rotates beyond the second angular range, the cup may engage the support arm which inhibits or prevents further rotational movement of the rearview mirror about the at least one axis. In use, a second force maybe required to rotate the rearview mirror unit within the second angular range. The second angular range may be greater than the first angular range. At least in certain embodiments, the first and second angular ranges do not overlap with each other. The second angular range may correspond to an exceptional or atypical range of movement for the rearview mirror (for example, in response to an Impact / collision force). The second angular range may be determined by the extent of the at least one part-conical surface of the transition section. A lower limit of the second angular range may correspond to a rotational angle of the rearview mirror unit when the transition section engages the cup. When rotating in the second angular range, the cup engages the transition section. The or each part-conical surface may intersect the ball at a secant plane intersecting the part-spherical surface. The secant plane may have a central angle greater than or equal to 45°, 55° or 65°. The secant plane may extend parallel to the reference plane described herein. This arrangement may enable a symmetrical range of movement of the rearview mirror before the cup engages the transition section. Alternatively, the secant plane may be oblique to the reference plane described herein. This arrangement may enable an asymmetrical range of movement of the rearview mirror before the cup engages the transition section. For example, a downwards rotational movement about a transverse axis may be greater than an upwards rotational movement about the transverse axis. The transition section may comprise one or more surface composed of a substantially continuous curve. The substantially continuous curve may extend in a direction parallel to the central axis of the support arm. This arrangement may reduce or avoid step changes in profile. This may result in a progressive increase in the force required to rotate the rearview mirror unit. The at least one part-conical surface may comprise a concave profile. The concave profile may progressively increase the opposing force as the rearview mirror unit is rotated about the at least one axis. The concave profile may have a radius which is greater than or equal to 3mm, 4mm or 5mm. Alternatively, the at least one part-conical surface may comprise a constant taper. The at least one part-conical surface may have a taper angle which is greater than or equal to 10°. The transition section may comprise a plurality of the part-conical surfaces. The part-conical surfaces may be spaced apart from each other in a circumferential direction. The at least one part-conical surface may comprise or consist of a lateral surface of a circular cone or a right circular cone. Alternatively, the at least one part-conical surface may comprise or consist of a lateral surface of an elliptical cone. The elliptical cone may comprise a major axis and a minor axis. The minor axis may be oriented vertically to provide an increased range of angular motion about the horizontal axis under the first loading condition. The at least one part-conical surface may comprise or consist of a truncated cone. The at least one part-conical surface may be truncated by the support arm. The mounting apparatus may comprise a base for mounting to the vehicle, for example to an interior roof panel of the vehicle or to an interior of the front windshield (windscreen). The support arm may extend from the base. The support arm may comprise a central axis. The central axis of the support may be coincident with the central longitudinal axis of the at least one part-conical surface. According to a further aspect of the present invention there is provided a rearview mirror assembly comprising a rearview mirror unit and a mounting apparatus as described herein. The rearview mirror unit may comprise a cup for receiving the part- spherical surface of the ball. The cup maybe in the form of a socket for receiving the ball. The cup may comprise one or more ball engaging member. The ball of the mounting apparatus may be located in the cup. At least one spring member may be provided to bias the one or more ball engaging member towards the ball. The at least one spring member may be configured to bias the one or more ball engaging member inwardly, for example radially inwardly towards the longitudinal axis. The one or more ball engaging member may engage the ball. The or each ball engaging member may comprise an arm. The at least one spring member may comprise a coil spring. The rearview mirror unit may comprise a reflective element, for example made of glass or metal. Alternatively, the rearview mirror unit may comprise a display screen for displaying an image captured by one or more imaging sensor, such as an optical camera. According to a further aspect of the present invention there is provided a vehicle comprising a mounting apparatus as described herein, or a rearview mirror assembly as described herein. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a schematic representation of a vehicle comprising a mounting apparatus for mounting a rearview mirror unit in accordance with an embodiment of the present invention; Figure 2 shows a longitudinal sectional view of the mounting apparatus and the rearview mirror unit shown in Figure 1; Figure 3 shows an enlarged view of a ball and a transition section of the mounting apparatus shown in Figures 1 and 2; Figure 4 shows a perspective view of the mounting apparatus shown in Figure 1. DETAILED DESCRIPTION A mounting apparatus 1 for mounting a rearview mirror unit 3 in accordance with an embodiment of the present invention will now be described wither reference to the accompanying figures. The rearview mirror unit 3 is provided in a vehicle 5. The mounting apparatus 1 and the rearview mirror unit 3 collectively form a rearview mirror assembly 13, as shown schematically in Figure 1. The rearview mirror unit 3 is provided to facilitate viewing a region behind the vehicle 5. As shown in Figure 1, the vehicle 5 in the present embodiment is an automobile. The rearview mirror unit 3 may be provided in other types of road vehicle 5. In the event of a collision, an occupant of the vehicle 5 may contact the rearview mirror unit 3. The mounting apparatus 1 is configured to control the movement of the rearview mirror unit 3 to help dissipate collision forces. The vehicle 5 is described herein using a reference frame comprising a longitudinal axis X, a transverse axis Y and a vertical axis Z. References herein to a longitudinal direction, a transverse direction and a vertical direction refer to directions along, or parallel to the corresponding axis of the reference frame. The vehicle 5 comprises a vehicle body 7. The vehicle body 7 in the present embodiment comprises a plurality of panels (not shown) which are fastened to each other, for example by welding, bonding or mechanical fasteners, such as bolts or rivets. The panels may, for example, be composed of a metal, such as aluminium or steel. Alternatively, or in addition, the panels may be formed of a composite material, such as carbon fibre. In a variant, the vehicle body 7 may be a composite structure. The vehicle body 7 forms a cabin 9 for occupants of the vehicle 5. The vehicle body 7 comprises a roof 11 supported by a plurality of pillars 13A-D. A windshield (windscreen) 15 is provided in an aperture 17 formed at the front of the vehicle body 7. As described herein, the rearview mirror unit 3 is mounted to an upper portion of the windshield 15. In a variant, the rearview mirror unit 3 could be mounted to the roof 11 of the vehicle body 7. The rearview mirror unit 3 is moveably mounted on the mounting apparatus 1. As shown in Figure 2, the rearview mirror unit 3 comprises a reflective element 19 mounted in a housing 21. The reflective element 19 has a reflective viewing surface. The reflective element 19 may, for example, be made of glass or metal. In a variant, the rearview mirror unit 3 may comprise a display screen for displaying an image captured by one or more imaging sensor, such as a rear-facing camera (not shown). The rearview mirror unit 3 comprises a cup 23 for cooperating with the mounting apparatus 1. The cup 23 forms a part-spherical inner surface 25 for cooperating with the mounting apparatus 1. In the present embodiment, the cup 23 is formed by an annular member 27 and a plurality of ball engaging members 29. The ball engaging members 29 project from the annular member 27 in a longitudinal direction. The annular member 27 has a radially inner surface 27A; and the ball engaging members 29 each have a radially inner surface 29A. The inner surfaces 27A, 29A of the annular member 27 and the ball engaging members 29 collectively form the part-spherical inner surface 25. As shown in Figure 3, the ball engaging members 29 each have a conical surface 29B which is tapered outwardly to form an entry portion of the cup 23. An annular knuckle 31 is formed at the interface between the inner surface 29A and the conical surface 29B of the ball engaging members 29. A spring member 33 is provided around an exterior of the ball engaging members 29. The spring member 33 is provided to apply a biasing force to the ball engaging members 29. The ball engaging members 29 in the present embodiment each comprise a projection 35 extending radially inwardly from the inner surface 29A to form a localised contact with the mounting apparatus 1. The mounting apparatus 1 comprises a bracket 41, a support arm 43 and a ball 45 for mounting the rearview mirror unit 3. The support arm 43 and the ball 45 are formed integrally with each other. The support arm 43 and the ball 45 may be moulded from a plastics or composite material. Alternatively, the support arm 43 and the ball 45 may be formed of metal, such as aluminium. As described herein, the ball 45 is configured to locate in the cup 23 to mount the rearview mirror unit 3. The entry portion of the cup 23 defined by the conical surface 29B facilitates locating the ball 45 inside the cup 23. The support arm 43 has a first end 43A and a second end 43B. The support arm 43 in the present embodiment comprises a tubular section having a tapered profile. The support arm 43 is hollow and a cable 47 is disposed therein for connection to an electronic display 48 incorporated into the rearview mirror unit 3. The cable 47 and the electronic display 48 may be omitted. The bracket 41 is provided at the first end 43A of the support arm 43 and Is configured releasably to mount the mounting apparatus 1 to a base 49 (shown schematically in Figure 1). The base 49 is fixedly mounted to the windshield 15. The base 49 in the present embodiment is adhesively fastened to an inner surface of the windshield 15. Other techniques may be employed to mount the base 49. The bracket 41 comprises a plurality of engagement members 53 for cooperating with the base 49 to mount the mounting apparatus 1. The support arm 43 comprises a central longitudinal axis X1, a transverse axis Y1 and a vertical axis Z1. The mounting apparatus 1 is mounted such that the longitudinal axis X1 extends substantially parallel to the longitudinal axis X of the vehicle 5. The mounting bracket 41 in the present embodiment comprises four (4) of the engagement members 53. The engagement members 53 may, for example, establish a bayonet-type connection with the base 49. Alternatively, or in addition, at least one mechanical fastener, such as a threaded bolt, may be provided to fasten the bracket 41 to the base 49. The ball 45 is provided at the second end 43B of the support arm 43. The ball 45 comprises a part-spherical surface 51 configured to locate in the cup 23 to mount the rearview mirror unit 3. The ball 45 and the cup 23 form a ball joint to enable the orientation of the rearview mirror unit 3 to be adjusted. The part-spherical surface 51 enables a rotational movement of the rearview mirror unit 3 about at least one axis. In the present embodiment, the part-spherical surface 51 enables rotation of the rearview mirror unit 3 about each of the longitudinal axis X1, the transverse axis Y1 and the vertical axis Z1. The part-spherical surface 51 enables rotation of the rearview mirror unit 3 about one or more of the transverse axis Y1 and the vertical axis Z1 within a first angular range. The first angular range corresponds to a normal movement range for the rearview mirror unit 3 to achieve an appropriate viewing angle for a driver of the vehicle 5. The first angular range is determined by the geometry of the part-spherical surface 51 and / or the cup 23 of the rearview mirror unit 3. The first angular range in the present embodiment comprises a first pitch rotation range (measured about the transverse axis Y1) and a first yaw rotation range (measured about the vertical axis Z1). Each of the first pitch and yaw rotation ranges maybe defined with respect to a reference plane extending perpendicular to the longitudinal axis X1. By way of example, the first pitch rotation range can have a upper limit of ±30°; and the first yaw rotation range can have an upper limit of ±30°. The first pitch rotation range and the first yaw rotation range may be the same as each other or may be different from each other. The rotation of the rearview mirror unit 3 about one or more of the transverse axis Y1 and the vertical axis Z1 within the first angular range can be performed under a first loading condition. The first loading condition represents a first load (or force) required to adjust the angular orientation of the rearview mirror unit 3 about one or more of the transverse axis Y1 and the vertical axis Z1. The angular orientation of the rearview mirror unit 3 can be adjusted within the first angular range upon application of the first load. The first loading condition is determined by the frictional forces at the interface between the part-spherical surface 51 and the plurality of ball engaging members 29. The mounting apparatus 1 comprises a transition section 55 disposed between the part-spherical surface 51 of the ball 45 and the support arm 43. The transition section 55 has a first end 55A coincident with the ball 45; and a second end 55B coincident with the support arm 43. The transition section 55 comprises one or more part-conical surface 57. The at least one part-conical surface 57 has a geometric centre disposed on the longitudinal axis X1 and is tapered inwardly in a direction away from the ball 45. In the present embodiment the transition section 55 comprises a conical surface 57 which extends around the circumference of the ball 45. The conical surface 57 may have a constant taper profile (i.e., a uniform taper). In the present embodiment, the conical surface 57 has a concave profile. The transition section 55 may be described as having a concave conical surface 57. The concave conical surface 57 typically comprises a radius which is greater than or equal to 2mm, 3mm or 5mm. In the present embodiment, the concave conical surface 57 comprises a radius of 5mm. The ball 45 locates in the cup 23 provided in the rearview mirror unit 3. In a variant, the transition section 55 may comprise a part-spherical surface having a larger diameter than that of the part-spherical surface 51 of the ball 45. The first end 55A of the transition section 55 is defined by a secant plane SP1 (shown in Figure 3) intersecting the part-spherical surface 51. The secant plane in the present embodiment extends perpendicular to the longitudinal axis X1. This arrangement enables symmetrical ranges of motion about the transverse axis Y1 and the vertical axis Z1. The secant plane SP1 has a central angle of approximately 60° in the present embodiment. The central angle may be less than or greater than 60°. In a variant, the secant plane may be oblique to the longitudinal axisXI. This arrangement enables asymmetric ranges of motion about the transverse axis Y1 and / or the vertical axis Z1. The interface between the first end 55A of the transition section 55 and the ball 45 is in the form of a substantially continuous surface in the present embodiment. In other words, the interface between the transition section 55 and the ball 45 is formed at least substantially without discontinuities or interruptions. In a variant, the interface between the first end 55A of the transition section 55 and the ball 45 may comprise a ridge or a projection. In other words, the interface between the transition section 55 and the ball 45 may be formed with a discontinuity or an interruption. As shown in Figure 3, the second end 55A of the transition section 55 has a larger diameter than the support arm 43. The interface between the second end 55B of the transition section 55 and the support arm 43 may comprise a stepped or tapered reduction in diameter. The rotation of the rearview mirror unit 3 about one or more of the transverse axis Y1 and the vertical axis Z1 causes the ball engaging members 29 on one side to be displaced towards the transition section 55; and the ball engaging members 29 on the diametrically opposed side to be displaced away from the transition section 55. The transition section 55 defines an angular limit or extent of the first angular range. In particular, the profile of the transition section 55 determines the first pitch rotation range (measured about the transverse axis Y1) and the first yaw rotation range (measured about the vertical axisZI) of the rearview mirror unit 3. The annular knuckle 31 of one or more of the ball engaging members 29 is aligned with the first end 55A of the transition section 55 when the rearview mirror unit 3 is rotated about the transverse axis Y1 by the first pitch rotation range and / or the vertical axis Z1 by the first yaw rotation range. Rotation of the rearview mirror unit 3 in a first direction about one or more of the transverse axis Y1 and the vertical axis Z1 at angles greater than the first pitch rotation range and the first yaw rotation range causes at least one of the ball engaging members 29 to engage the transition section 55. Typically, the annular knuckle 31 of one or more of the ball engaging members 29 contacts the concave conical surface 57 of the transition section 55. The ball engaging members 29 are moveable over the concave conical surface 57 of the transition section 55. However, the concave conical surface 57 diverges away from the part-spherical surface 51 of the ball 45, thereby resisting or opposing the movement of the ball engaging members 29 over the concave conical surface 57. The transition section 55 is operative to resist further rotation of the rearview mirror unit 3 in the first direction about one or more of the transverse axis X1 and the vertical axis Y1 at angles greater than the first pitch rotation range and the first yaw rotation range respectively. The transition section 55 defines a second angular range in which the rearview mirror unit 3 can rotate relative to the mounting apparatus 1. The first and second angular ranges are discrete from each other and do not overlap. Moreover, the second angular range is composed of angles having a magnitude which is greater than the magnitude of the angles in the first angular range. The second angular range comprises a second pitch rotation range (about the transverse axis Y1) and a second yaw rotation range (about the vertical axis Z1). Each of the second pitch and yaw rotation ranges may be defined with respect to a reference plane extending perpendicular to the longitudinal axis X1. By way of example, the second pitch rotation range can have a lower limit of ±30°; and the first yaw rotation range can have a lower limit of ±30°. The upper and lower limits may have a positive (+ve) or negative (-ve) value depending on a measurement direction about the respective axis. It will be understood that the ball engaging members 29 travel relative to the transition section 55 in a circumferential direction when the rearview mirror unit 3 is rotated about the longitudinal axis X1. As such, rotation about the longitudinal axis X1 is typically not constrained by the transition section 55. The transition section 55 does not prevent further rotational movement of the rearview mirror unit 3 in the first direction at angles which are greater than the first pitch rotation range and the first yaw rotation range. Rather, the further rotation of the rearview mirror unit 3 about one or more of the transverse axis Y1 and the vertical axis Z1 in the first direction can be performed under a second loading condition. The second loading condition corresponds to a force which is greater than the first loading condition. Thus, the rotation of the rearview mirror unit 3 about one or more of the transverse axis Y1 and the vertical axis Z1 can be performed at angles greater than the first pitch rotation range and the first yaw rotation range upon application of the second load. The concave conical surface 57 applies an opposing force to one or more of the ball engaging members 29 to resist rotation of the rearview mirror unit 3 about one or more of the transverse axis Y1 and the vertical axis Z1. The continued rotation of the rearview mirror unit 3 about the one or more of the transverse axis Y1 and the vertical axis Z1 in the same direction causes the opposing force to increase progressively as the one or more of the ball engaging members 29 travel relative to the transition section 55. The continued rotation of the rearview mirror unit 3 may cause one or more of the ball engaging members 29 to deform or deflect. The spring member 33 is operable to bias the one or more ball engaging members 29 towards a neutral (undeformed) position. As described herein, the rearview mirror unit 3 is rotatable about one or more of the transverse axis Y1 and the vertical axis Z1 within the first angular range under a first loading condition. The first angular range corresponds to a normal movement range. The first loading condition comprises a first force which is substantially constant within the first angular range. When rotating in the first angular range, the cup 23 is clear of (i.e., spaced apart from) the transition section 55. When rotating at angles greater than those defined by the first angular range, the cup 23 engages the transition section 55. The rearview mirror unit 3 is rotatable about one or more of the transverse axis Y1 and the vertical axis Z1 at angles greater than those of the first angular range under a second loading condition. The second loading condition comprises a second force which is greater than the first force. In the present embodiment, the second force increases as the angular rotation of the rearview mirror unit 3 increases beyond the first angular range. The rotation of the rearview mirror unit 3 to angles greater than the first angular range are exceptional or atypical. For example, the rotation of the rearview mirror unit 3 beyond the first angular range corresponds to a scenario in which an impact or collision force is applied to the rearview mirror unit 3. By permitting rotation of the rearview mirror unit 3 under the second loading condition, the transition section 55 may help to dissipate impact energy. At least in certain embodiments, this may help increase the time period over which collision forces are absorbed, thereby reducing the peak magnitude of the collision forces. In the embodiment described herein, the transition section 55 is profiled such that, after the initial rotation in the first angular range, the force required to rotate the rearview mirror unit 3 about one or more of the transverse axis Y1 and the vertical axis Z1 increases progressively. This may help to provide a continuous or progressive absorption of collision energy. 5 It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application. The mounting apparatus 1 described herein provides a swivel mount arrangement for a rearview mirror unit 3. The rearview mirror unit 3 could comprise a screen for displaying an image of a region to a rear of the vehicle 5, for example captured by one or more imaging sensor, such as an optical camera, provided on the vehicle 5. The one or more imaging sensor may comprise one or more optical camera. The one or more imaging sensor may be rear-facing, 10 i.e. facing towards a rear of the vehicle 5. The mounting apparatus 1 could be used in other applications, for example to mount a display screen (not shown) in the vehicle 5. For example, the mounting apparatus 1 could be used to mount a display screen to a dashboard or centre console of the vehicle 5. The ball 45 and the transition section 55 may advantageously absorb collision energy in the event of an impact. 15

Claims

1. A mounting apparatus for mounting a rearview mirror unit in a vehicle; the mounting apparatus comprising:a support arm;a ball disposed at an end of the support arm, the ball comprising a part-spherical surface configured to engage with a cup provided in the rearview mirror unit to enable a rotational movement of the rearview mirror unit about at least one axis under a first loading condition; anda transition section disposed between the part-spherical surface of the ball and the support arm, the transition section having at least one part-conical surface configured to engage the cup provided in the rearview mirror unit to constrain the rotational movement of the rearview mirror unit about the at least one axis under the first loading condition and to enable further rotational movement of the rearview mirror unit about the at least one axis under a second loading condition, wherein the second loading condition is greater than the first loading condition.

2. A mounting apparatus according to claim 1, wherein the at least one part-conical surface is configured to engage the cup and generate an opposing force to impede the rotational movement of the rearview mirror unit about the at least one axis under the second loading condition.

3. A mounting apparatus according to claim 2, wherein the at least one part-conical surface is profiled such that the opposing force increases progressively as the rearview mirror unit rotates about the at least one axis.

4. A mounting apparatus according to any one of claims 1, 2 and 3, wherein the or each part-conical surface intersects the ball at a secant plane intersecting the part-spherical surface, the secant plane having a central angle greater than or equal to 45°.

5. A mounting apparatus according to any one of claims 1 to 4, wherein the mounting apparatus enables rotation of the rearview mirror unit within a first angular range under the first loading condition; and enables rotation of the rearview mirror unit within a second angular range under the second loading condition; wherein an upper limit of the first angular range which is less than or equal to a lower limit of the second angular range.

6. A mounting apparatus according to any one of the preceding claims, wherein the transition section comprises one or more surface composed of a substantially continuous curve.

7. A mounting apparatus according to any one of the preceding claims, wherein the at least one part-conical surface has a concave profile.

8. A mounting apparatus according to claim 7, wherein the concave profile has a radius which is greater than or equal to 3mm.

9. A mounting apparatus according to any one of the preceding claims, wherein the at least one part-conical surface comprises or consists of a truncated cone.

10. A rearview mirror assembly comprising a rearview mirror unit and a mounting apparatus as claimed in anyone of the preceding claims, wherein the rearview mirror unit comprises a cup comprising one or more ball engaging member, the ball of the mounting apparatus being located in the cup.

511. A rearview mirror assembly as claimed in claim 10, wherein at least one spring member is provided to bias the one or more ball engaging member towards the ball.

12. A vehicle comprising a mounting apparatus according to any one of preceding claims 1 to 9, or a rearview mirror 10 assembly according to claim 10 or claim 11.14

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