Motorcycle with automatically adjustable mirror to reduce image movement

A motorcycle mirror mounting system that controls the position of the mirrors of a motorcycle during tilting and/or turning of the motorcycle. A tilt sensor detects the degree and direction of tilting of the motorcycle frame and provides data representative thereof to a central controller. In accordance with its adjustment determinations, the controller acts through one or more servo control circuits to continuously adjust the positions of the mirrors to maintain the mirrors in positions providing substantially the same view to the rear as during straight driving. Thus, an image that would normally appear near the center of a mirror during straight riding, and which would appear to move either to the left or right of, and toward either the upper or lower boundaries of, the mirror during tilting of the motorcycle, is maintained substantially at the center of the mirror. If the mirrors are mounted on the motorcycle handlebars, then a turn sensor senses the degree and direction of turning of the mirrors relative to the motorcycle frame and provides data representative thereof to the central controller which acts through the servo control circuits to adjust the mirror positions for the turning as well as the tilting.

BACKGROUND OF THE INVENTION 
The present invention pertains to a motorcycle mirror mount that 
automatically adjusts the rear view mirrors of a motorcycle to present 
substantially the same view during tilting and turning of the motorcycle 
as during straight riding, regardless of the degree and direction of tilt 
or turn of the motorcycle. 
Unlike automobiles and other vehicles that ride on three or more wheels, 
two-wheeled motorcycles, motorscooters and the like lean or tilt when the 
operator turns to the right or left, as when turning a corner, changing 
lanes on a highway, or simply following the curvature of a road. 
Motorcycles generally have rear view mirrors mounted on them to enable the 
operator to monitor traffic and road conditions behind him. During turns 
the motorcycle mirrors tilt with the frame of the motorcycle, with the 
result that one mirror is raised to an elevated position with respect to 
its position during straight riding while the other mirror is lowered. On 
some motorcycles, the mirrors are mounted on a wind fairing that is 
fixedly connected to the motorcycle frame. However, on other motorcycles 
the mirrors are mounted on the handlebars, with the result that when the 
front fork-handlebar assembly is turned to cause the motorcycle to turn, 
the mirrors are also turned with respect to the frame of the motorcycle. 
Motorcycle operators often experience difficulty in detecting vehicles 
behind them, for example vehicles approaching the motorcycle from either 
the left rear or right rear. This problem is exacerbated as the motorcycle 
tilts during a turn. Due to the tilting the motorcycle operator has a 
significantly diminished view behind him. If the turn is great, with a 
high degree of tilting and/or turning, the operator cannot utilize 
conventionally mounted mirrors to see behind him, but instead must either 
turn his head or look beneath his arm on the side toward which his vehicle 
is tilting. Either of these maneuvers by the operator is difficult to 
execute while wearing a helmet. Moreover, both are unsafe, as they require 
a prolonged time without viewing the road ahead, as compared with a quick 
glance at the rear view mirrors. This situation is even worse when the 
mirrors are mounted on the motorcycle handlebars and so turn with respect 
to the motorcycle frame as the operator turns the front wheel of the 
motorcycle. 
Adjustable mirror mounts are known for other vehicles. For example, U.S. 
Pat. No. 3,469,901 discloses an electrical system for automatically 
angularly adjusting the mirrors on the cab of a tractor trailer. A series 
of spaced electrical contacts is arranged on the fifth wheel of the 
tractor, while the kingpin plate of the trailer carries a conducting bar 
adapted to engage the contacts as the tractor turns with respect to the 
trailer. Contact between the various electrical contacts and the conductor 
bar causes activation of an electromagnetic device for pivoting or turning 
the rear view mirrors to provide the operator with an appropriate rear 
view both during straight driving and during turning. 
U.S. Pat. No. 3,749,480 discloses another automatic tractor-trailer mirror 
rotation system, including a relative rotation sensor, an electronic 
signal generator, a motor, and control circuitry for coupling the motor to 
the signal generator and for providing a feedback signal to the signal 
generator. The system rotates either the right or the left rear view 
mirror relative to the right or left rear wheel as the tractor turns 
relative to the trailer. The system is said to be very simple to install 
without requiring substantial modification to the vehicle. 
Other self-aligning rear view mirror systems are disclosed in, for example, 
U.S. Pat. Nos. 3,199,075; 3,383,154; and 3,640,609. U.S. Pat. No. 
3,199,075 discloses a system which moves the mirror between predetermined 
positions in response to operation of the right or left turn signal 
indicator. U.S. Pat. No. 3,383,154 shows a mechanical arrangement, 
utilizing a weight, for moving the mirror according to a particular ratio 
between the arcuate motion of the weight and the arcuate motion of the 
mirror. U.S. Pat. No. 3,640,609 discloses a hydraulic system responsive to 
the rotation of a shaft in the vehicle steering column for controlling the 
mirror position. 
SUMMARY OF THE INVENTION 
The present invention is a motorcycle mirror mounting system that controls 
the position of the mirrors of a motorcycle during tilting and/or turning 
of the motorcycle. A tilt sensor detects the degree and direction of 
tilting of the motorcycle frame and provides data representative thereof 
to a central controller. In accordance with its adjustment determinations, 
the controller acts through one or more servo control circuits to 
continuously adjust the positions of the mirrors to maintain the mirrors 
in positions providing the motorcycle operator with substantially the same 
view to the rear during such tilting or turning as is provided during 
straight driving. Thus, an image that would normally appear near the 
center of a mirror during straight riding, and which would appear to move 
either to the left or right of, and toward either the upper or lower 
boundaries of, the mirror during tilting of the motorcycle, is maintained 
substantially at the center of the mirror. 
The motorcycle mirror is mounted in a mirror mount, and a support locates 
the mirror a predetermined distance laterally ourwardly from the frame of 
the motorcycle in a predetermined position with respect to the motorcycle 
seat so that the mirror provides a selected rearward view. The mirror is 
pivotally mounted, permitting it to pivot with respect to the 
predetermined position. A tilt sensor is provided for sensing tilting of 
the motorcycle in relation to a vertical plane through the motorcycle 
frame. The tilt sensor output is applied to a central controller which 
controls the mirror position to continuously provide the motorcycle 
operator with a view to the rear that is substantially equivalent to the 
selected rearward view that is provided during straight riding with the 
mirror in the original predetermined position. 
One embodiment of the mirror mounting system according to the present 
invention is particularly suited for use with handlebar mounted mirrors 
and includes a turn sensor for detecting rotational movement of the front 
fork-handlebar assembly of the motorcycle and the mirror with respect to a 
plane through the motorcycle frame. The central controller receives a data 
signal, derived from the degree and direction of turn sensed by the turn 
sensor, and in turn acts through one or more servo circuits to further 
adjust the mirrors according to the degree of turn. 
The system can be entirely analog, or the sensor outputs can be converted 
to digital signals, permitting a microprocessor to be utilized as the 
central controller.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION 
As depicted in FIG. 1, as a motorcycle 12, with a motorcycle operator 10 
riding thereon, turns to follow a curve or turn in a road, motorcycle 12 
and rider 10 tilt from the vertical plane passing through the motorcycle 
frame. In contrast, during straight riding, the motorcycle and operator 
generally remain in a vertical plane. Motorcycle 12 is equipped with rear 
view mirrors 14 and 16. 
FIG. 2 illustrates the view provided to the operator by rear view mirrors 
14 and 16 during straight riding. As illustrated, each of mirrors 14 and 
16, at approximately the center thereof, shows an image 18 of a vehicle 
that is travelling behind the motorcycle. If mirrors 14 and 16 are mounted 
by means of conventional mirror mounts, as the motorcycle 12 tilts one of 
mirrors 14 and 16 is moved upwardly and the other is moved downwardly, 
both with respect to their FIG. 2 straight riding position. As a result, 
image 18 appears to move across the reflective surfaces of the mirrors and 
partially or fully to disappear. Thus, as illustrated in FIG. 3, when 
motorcycle 12 tilts to the left, right side mirror 14 moves upwardly and 
left side mirror 16 moves downwardly, and so image 18 moves to the lower 
right portion of mirror 14 and to the upper right portion of mirror 16, 
almost disappearing from the operator's view. The opposite situation 
occurs during tilting of the motorcycle to the right, causing right side 
mirror 14 to move downwardly and left side mirror 16 to move upwardly. 
FIG. 1 depicts mirrors 14 and 16 mounted on the handlebars 28 of motorcycle 
12. In contrast, FIG. 4 is a perspective view of a motorcycle 20 having a 
wind fairing 26 in front of the handlebars 28 to reduce wind resistance, 
with mirror mounts 22 and 24 mounted on fairing 26. Handlebars 28 rotate 
within fairing 26 with respect to the fairing and the motorcycle frame 30; 
however, mirror mounts 22 and 24 and mirrors 14 and 16 do not rotate with 
the turning of the handlebars. 
FIG. 5 is an enlarged, cutaway view in partial schematic form of mirror 
mount 22 in accordance with one embodiment of the present invention, and 
mirror mount 24 can be essentially the same. Mirror mount 22 includes a 
support element 40, for securing the mount to the motorcycle, and a 
housing 42. Support element 40 is sufficiently long to insure that housing 
42 projects outwardly from the sidewalls 44 (FIG. 4) of fairing 26, for 
example being at least about six inches horizontally from the sidewall 
More preferably, support element 40 provides at least a six inch clearance 
between housing 42 and any point along frame 30. 
Housing 42 may be of rounded, conical or any other shape and has an opening 
46 accommodating a mirror assembly 47. Housing 42 is connected to support 
element 40 by means of swivel mount 50 which may be of any conventional 
type, preferably of the type permitting rough hand adjustment of the 
housing 42 and mirror 48 relative to element 40 and fairing 26. Mirror 
assembly 47 includes a mirror member 48 which is supported within housing 
42 by a support plate 52. Support plate 52, in turn, is pivotably held 
within housing 42 by freely movable means such as universal joint 54. 
Universal joint 54 permits limited pivoting of mirror assembly 47 about 
orthogonal axes, for example the vertical and horizontal axes of support 
plate 52 and mirror member 48. Alternatively, support plate 52 could be 
held within housing 42 by means of a ball-and-socket joint affixed to the 
rear wall of housing 42 and permitting pivoting about the same axes. 
A control system 60 for mirror mount 22 or 24 is provided on a printed 
circuit board 62 positioned within housing 42. As seen in FIG. 6, control 
system 60 includes a central controller 64 for controlling the pivoting of 
plate 52 in response to the tilting of the motorcycle. Central controller 
64 receives data representative of the direction of tilt and the degree of 
tilt from tilt sensor 66. By way of example, tilt sensor 66 could be of 
the gravity reference type. Accordingly, tilt sensor 66 could comprise a 
pendulous element suspended inside a case. Tilt sensor 66 provides an 
output signal, as from a potentiometer, dependent upon the deflection of 
the pendulous element from its vertical position when motorcycle 20 tilts 
to the right or to the left. By way of example, to differentiate between a 
right tilt and a left tilt, tilt sensor 66 could provide a positive going 
output signal to indicate a right tilt and a negative going output signal 
to indicate a left tilt. 
Alternatively, tilt sensor 66 could comprise a gyro attitude transducer in 
which pivoting about a horizontally oriented gimbal axis is quantified to 
provide a similar output signal. Further still, tilt sensor 66 could 
comprise a mercury switch for providing a signal upon displacement of a 
mercury bubble either to the right or to the left within a containment 
tube having its longitudinal axis normally aligned with the horizontal 
when the motorcycle is vertical. 
Controller 64 determines the adjustment necessary to mirror member 48 to 
provide a full rear view corresponding substantially to that provided 
during straight riding and applies appropriate signals to vertical and 
horizontal servo control circuits 82 and 84 to cause the servo control 
cicruits to control corresponding servo motors 86 to pivot plate 52 and 
mirror 48 about a pair of orthogonal axes of mirror assembly 47. 
When system 60 is activated or when it is deactivated, or preferably both, 
as by the operation of the motorcycle ignition switch (not shown) by the 
motorcycle operator, controller 64 causes servo circuits 82 and 84 to 
control motors 86 and to automatically move mirror member 48 into an 
initial position, which preferably is a position providing a straight 
riding rear view for riders of average height. This initial position may 
be pre-set by the motorcycle operator by manual ad]ustment of housing 42 
on swivel mount 52. Thereafter, system 60 maintains mirror member 48 in 
this straight riding position with respect to housing 42 during straight 
riding. 
When tilt sensor 66 detects tilting of the motorcycle the tilt sensor 
generates a voltage signal indicating the detected direction and degree of 
tilting. This voltage signal is applied to controller 64, and in response 
controller 64 applies signals to servo control circuits 82 and 84 to cause 
motors 86 to move mirror member 48 to provide the requisite 
straight-riding view during the tilting. As a result, mirrors 14 and 16 
are adjusted to center image 18 substantially at their central portions. 
In the foregoing, each mirror mount has been described as being secured to 
fairing 26 of motorcycle 20 so as not to rotate with respect to frame 30 
during turning of handlebars 28. Mirror mounts 22 and 24, however, could 
be secured to handlebars 28, as depicted in FIG. 1. FIG. 7 shows modified 
system 60' in accordance with the present invention which, in addition to 
the tilt circuitry of FIG. 6, includes turn sensor 88. Turn sensor 88 
detects the relative rotation of handlebars 28 with respect to the 
motorcycle frame 30. Turn sensor 88 could comprise an electrical 
contact-based device that operates similar to the electrical 
contact-conduction bar turn sensor of U.S. Pat. No. 3,469,901. 
Alternatively, turn sensor 88 could comprise any other rotation sensing 
device as is known to those skilled in the art. 
As with tilt sensor 66, turn sensor 88 applies a signal to controller 64 
representing the degree and direction of rotation of handlebars 28 with 
respect to frame 30. Central controller 64 applies signals to servo 
control circuits 82 and 84 to cause motors 86 to pivot the mirror assembly 
47 to compensate for the movement away from the straight riding view 
attributable to rotation of handlebars 28. Otherwise, system 60' is 
similar to system 60. 
Central controller 64 and servo control circuits 82 and 84 can be 
conventional servomechanism control circuitry designed to control the 
position of mirror assembly 47 in response to the output from tilt sensor 
66 and/or turn sensor 88. See, for example, the two-volume treatise 
Servomechanism and Regulating Svstem Design, Chestnut and Mayer, John 
Wiley & Sons, Inc., Second Edition, 1959. Alternatively, central 
controller 64 can include a microprocessor, in which event central 
controller 64 also might include an analog to digital converter between 
tilt sensor 66 and the microprocessor and between turn sensor 88 and the 
microprocessor. 
Although the present invention has been described with reference to 
preferred embodiments, numerous modifications, rearrangements, and 
substitutions could be made, and the result would remain well within the 
scope of the invention.