Note: Descriptions are shown in the official language in which they were submitted.
~z~s~
REMOTELY ACTUATED REARVIEW
MIRROR FOR AUTOMOTIVE VEEIICLES
Brief Summary of the Invention
This is a division of our Canadian patent appllcation
No. ~09,652, filed August 18, 1982.
This invention relates to rearview mirrors for automo-
-tive vehicles and, more particularly, to an improved inside
rearview mirror which is particularly adapted for use with
automotive vehicles and which may be very conveniently
indexed, by the driver of such a vehicle, from a full re-
flectance mode (day) to a partial reflectance mode (night~
for glare protection from light emanating from the headlights
of vehicles approaching from the rear. Rearview mirrors
embodying the present invention incorporate a prism type
reflective element which is substantially identical to the
prism type reflective elements utilized in lever operated
day-night mirrors conventionally provided on modern day
automobiles. As is well known in the art, the driver of a
vehicle equipped with such a lever operated mirror may adjust
the mirror to a full reflectance mode or a partial reflectance
mode by turning or flipping a lever located on the base of
the mirror. However, such prior lever operated mirrors are
often not used by numerous drivers because of the inconven-
ience involved in reaching up to the mirror to make the
desired adjustment. In general, rearview mirrors embodying
tlle present invention may be conveniently indexed to the
alternate reflective mode each time that an electrical switch
button is depressed by the driver of the vehicle, the switch
button being positioned in a convenient location such as on
or near -the steering wheel of the vehicle. The power
required to index the reflective element of the mirror is
drawn either from the vehicle's electrical system or from a
sel~ contained battery.
IIeretofore, automatic mirrors have also been devised
for the purpose of automatically shif-ting the reflective
element incorporated therein between the full reflectance
and partial reflectance modes without requiring any action
on the part of the driver of the vehicle. However, prior
automatic mirrors of the indicated character are relatively
expensive as compared with mirrors en~odying the present
invention, and many prior automatic mirrors have deficiencies
(such as, for example, noisy operating characteristics,
excessive vibration characteristics, high electrical current
requirements, ungainly connections, poor clarity, poor per-
formance characteristics at low operating temperatures, and
slow operating times) that preclude practical operation of
the devices with the result that lever operated mirrors of
the type mentioned hereinabove are still normally provided
as part of the orlginal equipment of automotive vehicles
manufactured throughout the world.
An object of the present invention is to overcome the
aforementioned as well as other disadvantages in prior
automotive vehicle mirrors of the indicated character and
to provide an improved remotely actuated rearview mirror
for automotive vehicles incorporating improved means for
indexing a reflective element, incorporated in the mirror,
successively between a full reflectance mode and a partial
~5 :reflectance mode through the agency of electrical switch
means positioned for easy accessibility by the driver of a
vehicle.
~ nother object of the presen-t invention is to provide
an improved remotely actuated rearview mirror incorporating
improved means whereby an indexing cycle of a reflective
elemen-t incorporated therein is initiated by momentary closure
of electrical switch means and once initiated, the indexing
cycle is completed.
-- 2
~2~
Another object of the present invention is to provide
an improved remotely actuated rearview mirror wherein circuit
operation is not initiated by any normal capacitance or radio
frequency coupling to the mirror whereby special shielding
requirements are obviated.
Another object of the present invention is to provide
an improved remotely actuated rearview mirror wherein
sustained closure of electrical switch means incorporated
therein results in only one indexing step and wherein such
electrical switch means must be opened and closed before
another indexing step is initiated.
Another object of the present invention i5 to provide
an improved remotely actuated rearview mirror incorporating
improved means for moving a reflective element between a
full reflectance mode and a partial reflectance mode and which
means is relatively low in cost and yet capable of withstand-
ing the severe electrical and physical environments normally
encountered in automotive vehicles.
Another object of the present invention is to provide an
improved remotely actuated rearview mirror which is relatively
light in weight, small in size, quiet in operation and free
of extraneous movement.
Another object of the present invention is to provide an
improved remotely actuated rearview mirror incorpora-ting
improved means for indexing a reflective element successively
between a full reflectance mode and a partial reflectance
mode with a minimum of electrical power.
Another object of the present invention is to provide an
improved remotely actuated rearview mirror incorporating
improved means for supporting the components -thereof whereby
vibration is reduced to a minimum.
~nother object of the present inven-tion is to provide
an improved remotely actuated rearview mirror that may be
economically manufactured, assembled and installed with a
minimum of time, labour and expense, and which mirror is
strong and rugged in construction and reliable in operation.
The above as well as other objects and advantages of -the
present invention will become apparent from tne following
description, the appended claims and the accompanying
drawings.
Brief Description of the Drawings
Figure l is a perspective view of a remotely actuated
rearview mirror embodying the present invention, showing the
same installed on the windshield of a vehicle, and also
illustrating a steering wheel wlth an electri.cal switch
mounted thereon for controlling the reflective state of the
mirror;
Figure 2 is an elevational view, with portions broken
away, of the mirror illustrated in Figure l as it faces the
rear of the vehicle;
Figure 3 is an elevational view of a portion of the
mirror illustrated in Figure l as it faces the front of the
vehicle, showing the same with the housing removed for
clarity of illustration;
Figure ~ is a cross sectional view of a portion of the
~5 structure illustrated in Figure 3, taken on the line 4-4
thereo:E;
F'igure 5 is a cross sectional view of a portion of the
structure illustrated in Figure 3, taken on the line 5-5
thereoE;
Figure 6 is a cross sectional view of a portion of the
structure illustrated in Figure 3, taken on the line 6-6
thereof;
~2~
Figure 7 is a cross sectional view of a portion of the
structure illustrated in Figure 3, taken on the line 7-7
thereof;
Figure 8 is a schematic exploded view of certain of the
components of the mirror illustrated in Figure l; and
Figure 9 is a schematic electrical diagram of the mirror
control circuitry embodying the present invention.
Detailed Description
Referring to the drawings, a preferred embodiment of
the invention is illustrated therein and is comprised of a
remotely actuated rearview mirror, generally designated 20,
which is adapted to be mounted on the inside of the wind-
shield 22 of an automotive vehicle through the agency of a
conventional mounting member 24 incorporating conventional
ball and socket means (not shown) permitting angular adjust-
ment of the mirror in a conventional manner. The outer end
portion 26 of the mounting menber 24 is fixed, for example
by an adhesive, to the windshield 22 while the inner end
portion of the mounting member is provided with a non-circular
mounting block 28 adapted to be received in a similarly shaped
hole 30 provided in a base 32, the base 32 being retained by
a screw 34. In the preferred embodiment illustrated, the
remotely actuated rearview mirror 20 includes a conventional
prism type reflective element 36 which is mounted on a
housing 38, the housing having top and bottom walls 40 and
42 integrally joined by side walls 44 and 46 and a rear wall
48 to define a chamber 50 which is open in the direction
:Eacing the rear of the vehicle. The prism type reflective
element 36 is retained by a grommet 52 fitted over the free
edge of the top, bo-ttom and side walls of the housing whereby
the reflective element 36 is permanently fixed to the housing
38. The housing 38, in turn, is pivotally connected -to the
base 32 through the agency of axially aligned trunnions 54
and 56 which are mounted in spaced, outwardly projecting
flanges 58 and 60, respectlvely, provided on the base 32,
the trunnions 54 and 56 being supported in bearings 62 and
64, respectively, formed integrally with the back wall of
the housing, as shown in Figures 3, 7 and 8~ whereby the
reflective element 36 and the housing 38 may be pivoted as
a unit relative to the base 32, the central portion of the
mounting member 24 passing through an opening 66 provided
in the rear wall 48 of the housing with sufficient clearance
to permit the pivotal movement of the reflective element and
the housing relative to the mounting member 24 whereby the
reflective element may be moved from a full reflective mode
to a partial reflective mode and thereafter returned to the
full reflective mode by pivoting the reflective element and
the housing as a unit about the aligned longitudinal axis of
the trunnions 54 and 56.
In the embodiment of the invention illustrated, a small,
unidirectional DC motor 68 is provided as the prime mover
for moving the reflective element 36 and the housing 38 be-
tween the full reflectance and partial reflectance positions.
The motor 68 includes a housing 69 which is mounted on the
base 32 thro~lgh the agency of a mounting bracket 70 that
~rj :includes a pair of L-shaped leg portions 71 and 72, which
encJage the front wall 74 of the motor housing, and an
.integral base portion 76 which engages the rear wall 78 of
the motor housing. The bottom wall 79 of the motor housing
69 is supported by an outwardly projecting flange 96 which is
:Eormed as an integral part of the base 32. The mounting
bracket 70 also carries electrical connectors 80 and 82 which
make electrical contact with the motor, and the electrical
:~2~
connectors 80 and 82 are soldered to a printed circuit board
136 which is fixed to the base 32, as with screws 138 and
140, the prin-ted circui-t board 136 being disposed within the
chamber 50 defined by the housing and carrying various compo-
nents and electrical conductor paths of the control circuitry
embodying the invention. The solder connection provides both
an electrical connection to the printed circuit board and a
mechanical support for -the mountiny bracket 70. Thus, the
mounting bracket 70 and the electrical connectors carried
thereby make the necessary electrical connections to the
motor 68 and also aid in the support and retention of the
motor.
~ three stage speed reduction, generally designated 84,
is provided for the motor 68, such speed reduction being
comprised of a drive pulley 86 which is fixed to the drlve
shaft 88 of the motor 68. By means of an O-ring belt 90,
the drive pulley 86 drives a pulley 92 carried by a shaf-t
94 supported by outwardly projecting flanges 96 and 98
provided on t.he base 32, the shaft 94 also carrying a pulley
100 which by means of an O-ring belt 102 drives an integral
pulley 104 and a pinion 110 carried by a shaft 106 also
suppor-ted by the flanges 96 and 98, the shafts 94 and 106
being retained by any suitable means, such as snap rings 108.
The pinion 110 drives a spur gear 112 mounted on the shaft
94. Integral wi-th the spur gear 112 are a switch cam 118 and
an eccell-tric cam 120 disposed in a passageway 122 defined by
the web portion 124 of a generally channel shaped bridge member
126. The bridge member 126 includes a flange portion 128 which
is held against the inside surface 130 of the reflective element
36. The bridge member 126 also includes a flange portion 132
which is fixed to the wall 48 through the agency of a screw
134. With such a construction, rotation of the eccentric cam
~a2~99~
120 causes -the eccentric bridge 126 to transla-te thereby
pivoting the reflective element 36 and the housing 38 as a
unit about the aligned axes of the trunnions 54 and 56 to
move the reflective element 36 between the full reflectance
and partial reflectance modes. rme switch cam 118 functions
to close and open the contac-ts of the limit switch Kl to
energize and de-energize the motor as will be described
hereinafter in greater detail, the contacts of the limit
switch Kl being open in both the full reflectance position
and the partial reflectance position of the reflective
element 36 and closed when the reflective element is inter-
mediate such positions.
In the embodiment of the invention illustrated, a
manually actuatable electrical switch K2 is provided which
is mounted on the steering wheel 142 of the vehicle and
positioned for convenient actuation by the driver of the
vehicle, the switch K2 being electrically connected by any
suitable electrical conductors in the mirror control circuitry
illustrated in Figure 9. While the switch K2 is illustrated
as being in the form of a push button switch, it will be
understood that other forms of manually actuatable switches
may be utilized. It will also be understood that the switch
K2 may be mounted in any other position convenien-tly access-
ible to the driver, as for example, the switch K2 may be
mounted on the turn signal lever TSL, on the tilt-wheel lever
IWL, on the dashboard DB or in any other position convenient
for the driver. Rotation of the unidirectionally driven DC
motor 68 is initiated by a momentary closing of the switch K2
whenever a change in reflective state is required. Circuit
action is such that an indexing cycle is initiated by a very
short closure of the switch K2, and once initiated, the index~
ing cycle is completed. Sustained closure of the switch K2
~2~
results in only one indexing step, and the switch K2 must be
opened and closed again to index another step.
Referring to Figure 9, the circuitry embodying the
present invention is illustrated therein. As shown in Figure
9, the circuit is energized by a positive voltage at the
terminal 144, which voltage may be supplied by the vehicle
electrical system or by a self-contained battery. The
terminal 146 is connected to the electrical system ground
such as the vehicle chassis. The terminal 148 iS the control
input which is momentarily connected to ground through the
switch K2 to initiate a change to the alternate reflective
state. The circuitry also includes the unidirectional DC
motor 6 8, the switches Kl and K2, diodes Dl, D2, D3 and D4,
a silicon controlled rectifier SCRl, capacitors Cl through
C4 and resistors Rl through R8, such components all being
electrically connected by suitable conductors as illustrated
in the drawings and as will be described hereinafter in
greater detail.
As previously mentioned, the ~midirectional DC Motor
68 rotates the eccentric cam 120 through the three stage
speed reduction 84 to move the reflective element 36 between
its reflective positions. The contacts of the switch Kl are
closed except when the reflective element 36 is in each of its
two stable positions. The contacts of the switch Kl open and
de-energize the motor 68 when the reflective element is
positioned in its desired reflective state.
The diodes Dl and D4 prevent damage to the circuit due to
incorrect wiring. The resistors Rl and R2 conduct current
generated by the motor 68 when it is de-energized and still
coasting. This provides braking action to prevent the re-
flective element 36 Erom coasting on through its stop positions
and continuing to oscillate under high supply vol-tage conditions.
The current conducted by the resistors Rl and P~2 while the
~2~
silicon controlled rectifier SCRl is conducting preven-ts
turn-off of the silicon controlled rectifier. Such turn-off
may otherwise occur due to an interruption of the motor current
caused by faulty brush contact in the motor 68. The resistors
Rl and R2 are preferably widely spaced and, in the embodiment
of the invention illustrated, are used in place of one
resistor to distribute the heat they dissipate. This preven-ts
damage from heat generated in the event that the resistors Rl
and R2 remain energized due to a fault condition. The
resistors Rl and R2 are also preferably made of a high tempera-
ture coefficient wire so that their resistance increases and
limits heating under the fault condition mentioned hereinabove.
The capacitor C3 is charged through the resistor R6/ and
the diode D2 is forward biased by current through the resistor
R7. The capacitor Cl limits rapid voltage excursions at the
anode 150 of the silicon controlled rectifier SCRl to prevent
unwanted turn-on of the silicon controlled rectifier. The
resistor R4 prevents turn-on of the silicon controlled
rectifier due to leakage current at its gate 152. The capaci-
tor C2 prevents turn-on of the silicon controlled rectifier
due to interference generated transient voltages at the gate.
The diode D3 adds to the turn-on noise margin of the silicon
controlled rectifier and prevents sinking of gate current
through the resistor R5 and a possibility of a resulting gate
turn-off oE the silicon controlled rectifier. The resistor
R3 limits motor current.
The switch Kl is actuated by the cam 118 in the gear
reduction unit, the switch Kl being open when the reflective
element 36 is in each of its stable positions. The switch Kl
closes during the traverse of the unit between each of its
stable positions. Closure of the switch Kl shorts the silicon
controlled rectifier allowing the silicon con-trolled rectifier
-- 10 --
9~
to turn-off, and the switch Kl continues to energize the motor
68 until the reflective element 36 has indexed to its next
stable position at which point the cam 118 opens the switch
Kl and the reflective element 36 comes to rest~
In the operation of the motor control circuit, closure
of the switch K2 discharges the capacitor C3 through the
resistor R8 and the diode D4. The capacitor C4 receives
negative charge from the capacitor C3 at the terminal 154
which goes negative. The diode D2 is reverse biased and the
cathode 156 of the silicon controlled rectifier goes negative
thereby forward biasing the diode D3 and causing gate current
to flow through the diode D3 and the resistor R5 into the
gate terminal 152 of the silicon controlled rectifier. The
silicon controlled rectifier then turns on and energizes
the motor 68 through the resistor R3. The cam 118 in the
gear reduction unit closes the switch Kl and the silicon
controlled rectifier is turned off. The reflective element
36 is then carried to its next stable position as previously
mentioned. Discharge of the capacitor C3 is rapid and the
switch K2 must be opened to allow the capacitor C3 to recharge
through the resistor R6 before another cycle can be initiated.
After turn-on of the silicon controlled rectifier, the
capacitor C4 charges rapidly and the diode D2 conducts the
motor current.
Typical values for the components of the circuitry
described hereinabove are as follows:
Rl 15 ohm
R2 15 ohm
R3 3.9 ohm
R4 1 K ohm
R5 100 ohm
R6 10 K ohm
R7 2.2 K ohm
~26~
~8 10 ohm
Cl .047 MFD, 250 V
C2 .022 MFD, 16 V
C3 3.3 MFD, 50 V
C4 4.7 ME'D, 10 V Nonpolar
Dl IN4004
D2 IN4004
D3 IN4148
D4 IN4004
SCR1 SC203D, Silicon Controlled Rectifier
In the operation of the mirror 20, upon entering -the
vehicle, the driver should adjust the reflective element 36
for good rearward vision. If the headlights of a vehicle
approaching from the rear tend to cause annoying glare, the
driver may momentarily close the switch K2 to initiate
movement of the reflective element 36 to the antiglare
position and the following chain of events will take place.
The motor 68 is energized and begins rotating to drive the
three stage speed reduction 84 to rotate the eccentric cam
120 which causes the eccentric bridge 126 to translate,
thereby moving the reflective element 36 and the mirror
housing 38 as a unit to the antiglare position. The contacts
oE the switch Kl open and de-energize the motor 68 when the
reElective element 36 is positioned in the desired antiglare
position. The reflective element 36 is then held securely in
th~ antiglare position until the source of the glare is removed.
Wherl the source of the glare is removed, the driver may again
momentarily close the switch K2 to signal the motor 68 to re-
initiate rotation, again driving the three stage speed reduction
8~ to cause the switch cam 118 and the eccentric cam 120 to
rota-te, thereby closing the limi-t switch Kl and also moving the
reflective element 36 -through -the agency of the eccentric
bridge -to return the reElective element to the full reflective
~2~
mode. A~ this point, the limit switch ~1 opens and the
cycle is completed. The reflective element 36 will then be
held securely in the full reflectance mode untll another
source of annoying glare is encountered, whereupon the driver
may cause the cycle to be repeated.
From the foregoing it will be appreciated that with the
present invention, a small~ very low cost unidirectional DC
motor is utilized as the prime mover for the reflectance
element. The use of a unidirectional DC motor driving through
a combination belt drive and gear drive system makes it
possible to have high force available to move the reflectance
element because several revolutions of the motor can be
utilized to do the work. The small motor that can be
utilized is significantly lighter in weight than a solenoid.
Moreover, the small motor and drive train embodying the
present invention allows -the total mirror package to be
similar to a standard day-night mirror in overall size.
Because of the high force available, the reflective element
can be permanently Eixed to the mirror housing and the
reflective element and -the housing moved as a unit to shift
from a Eull reflectance mode to a partial reflectance mode
and back again whereby a distinct advantage in controlling
vibrations is ob-tained. Moreover, no return spring systern
is required, so the en-tire system is tight and free of
extraneous movement which would con-tribute to vibration
problems. The belt drive in the first two stages of ~he
speed reduction unit 84 acts to silence the operation of
the mirror 20, thereby making it quieter than solenoid
operated devices. (I-t is preferred tha-t the O-rings in the
Eirst two stages oE the speed reduction unit 84 be made of
silicone rubber since such rubber is resistant to high
temperatures and retains its flexibility at very low
- 13 -
939~3
temperatures~) The third stage of the speed reduction unit
84 is a low cost pinion and spur gear arrangement with the
result that the speed reduction system is very quiet and
can be produced at lost cost.
The switch K2 provides a single pole momentary contact
-to ground and the circuitry embodying the present invention
accommodates this mode of switch action so that the switching
function is accomplished through a single control line to the
mirror. Circuit action is such that an indexing cycle is
initiated by a very short closure of the switch, and once
lnitiated, the indexing cycle is comple-ted. Circuit operation
is not initiated by any normal capacitance or radio frequency
coupling to the control line or to the mirror circuit, and
lines to the mirror may be routed normally with no special
shielding requirements Moreover, the circuit components
are low in cost and yet are able to withstand the severe
electrical and physical environments encountered in automotive
vehicles.
The mounting of the reflective element permanently on
the mirror housing and moving the reflective element and the
housing as a unit reduces vibration to a minimum, and the
reflective element and the housing are firmly held in both
the full reflectance and partial reflectance positions. The
limit switch Kl that controls the end positions of the
mirror cycle is operated Erom the switch cam 118 so that the
final positions are closely controlled.
While a preferred embodiment of the invention has been
illustrated and described, it will be understood that various
changes and modifications may be made without departing from
the spirit of the invention.
- 14 -
