Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to a rear view mirror for a
motor vehicle which is movable automatically between a normal
viewing position and an anti-glare position in which glare
from light reflected from the mirror is reduced.
Such automatically adjusting rear view mirrors are
~nown and the present invention provides such a rear view
mirror of a construction which .is simple and inexpensive to
manufacture.
Accor~;ng to the present invention there is provided
a rear view mirror for a motor vehicle, comprising
(a) a housing including
(1) a recessed back plate portion;
~ar,~
(2~ a front ~a~e portion adapted for connection
with said ~ack ~ ~e portion to define a
cham~er, said housing containing a recess
in the inner surface of the lower portion
:~ ~ thereof, said recess extending parallel
~: wi~h said front plate portion;
~bl a mirror pivotally mounted within said housing
chamber, the lower edge of said m~rror being
arranged within said housing recess,-said mirror
`~ ~eing operable to pivot ~etween a normal position
wherein said mirror ~s arranged adjacent and
enerally parallel to sald front frame portion
. and an anti~glare position w~erein said mirror
diver~es ~rom said front frame portion in the
d~rection of the upper edge of said mirror;
(c)~ m,eans ~or biasing said mirror toward its normal
: position; and
(d~: mleans for pi~otrn~ said mLrro~r toward:its anti
;~ ~ : glare position including ~:
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(1) a unitary electrical assembly mounted on
said back plate portion within said chamber
opposite the rear portion of said mirror, said
assembly containing an electrical circuit
including
~a~, a printed circuit board;
(b~ a photosensor mounted on said printed
circuit ~o,ard for detecting light inci-
dent on said mirror;
~cl a solenoid coil for generating a magnetic
f~eld; and . .
(dl transistor circuit means for energizing
said coil in response to incident light
on the photosensor above a pred~termined
intensit~; and
: (,21 metallic plate means mounted on the rear -
portion of said mirror opposite said electrical
~; a~sembl~, ~hereE~y w~en light above the
.
-~: predetermined intensity strikes said photo-
: ,20 sensor, said solenoi~ co~1 generates a
magnetic ~ield which~attracts said metallic ~'
plate means, t~ere~y pivoting said mirror
: to its ant~glare posit~on. :
By providing in accord~nce~:with.the invention said
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: electrical assem~ly~as a single untt which is mounted within
the hou:sing it~is possi~le su~stan~ially to reduce manu~
facturin~ costs since the housing and electrical asse,mbly :
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may be manu~actured separately ana su~se~uen~ly:assembled.
: The two portions o~ the:housing are prefera~ly formed ' :
' : 30 as plastics mouldlngs~ut ma~ if;dffsired ~e formed as metal
~:' parts~ Pre~e:ra~ly the t~o parts are provided with mechan~
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ically interengaging means, for example studs engaging in
recesses to secure the two parts together. All this lends
itself to simplicity in manufacture.
The ~ottom edge of the mirror glass may carry a
cylindrical element movable within the recess of the
housing to facilitate pivotal movement o~ the mirror glass.
A pivot for the mirror glass is preferably provided by a
frame member of the solenoid engaging co-operating means on
the mirror and spring means biasing the frame member into
engagemen~ with the co-operating means.
A holding circuit may ~e provided in the electrical
assembly coupled with the solenoid coil for reducing the
level of energization o~ the coil from ltS initial ener-
gization to a level sufficient to maintain the mirror in
the anti-glare position. Such holding circuit may include
a pair o~ electrical contacts operated ~y coil energization
either to short out part of the solenoid coil or to switch
in a series resistance with the coil.
A mounting arm may be coupled to the housing, the
mounting arm providing at its free end a plane surface
where~y the mountin~ arm may ~e secured by an adhesi~e
bond to a plane surface of the motor vehicle in order to
provide a secure mounting of the mirror to such plane surface.
The mounting arm is preferably coupled to the housing
,~
by a ~all and socket joint. A socket formed on the housing
preferabl~ comprises an elongate ~ore which tapers in~ardly
in order to accommodate ~alls of di~ferent sizes such as
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may occur in motor vehicles ~a~ing~mounting arms already
installed~ ~ locking mem~er may ~e positioned within the
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bore after insertion of the ~all member into the ~ore in
; order ~o retain the ~all member within the bore. The locking
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member may be secured in position by fixing screws engaging
in registering apertures in the locking member and the
housing. As an alternative~ the locking member may be a
force fit within tha bore so that the positioning o E the
locking member serves to secure the locking member.
A preferred embodiment o:E the invention will now be
described with reference to the accompanying drawings
wherein:- .
Figure 1 is a front elevation of a preferred embodiment
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of a rear view mirror according -to -the invention, wi-th the
mirror glass partly broken away to show internal details of
the mirror;
~igure 2 is a cross-sectional view of the mirror taken
along the line II-II of Figure 1, the mirror glass being
shown in the normal viewing position;
Figure 3 is an exploded sectional view of the mirror
along the line II-II of l~i.gure 1, the mirror glass be:ing
shown in the anti-glare position;
Figure ll is an exploded view on an enlarged scale of a
ball and socket joint at the rear of the mirror housing
coupling a mounting arm to the mirror;
Figure 5 is a circuit diagram of the electrical assembly
of the mirror; and
Figure 6 is a circuit diagram of an alternative form of
~ electrical assembly for the mirro;r.
: Referring to the drawings there is shown arear view mirror
comprising a housing 2 formed as a plastic moulding in two
parts, namely a back plate part 4 and a front frame part 6.
Located between the two parts of the housing is a mirror glass
.~: :
8 movable between a normal vlewing position ~Figure 2) and an
anti-glare position (Figure 3) in which glare from light
reflecte:d from the mirror is reduoed. The mirror is
pivotable about a pivot 10. An el~ectrical assembly 12 formed
as a single unit is mounted wit~hin back plate 4. The:assembly
~: includes a photosensor 14 which receive9 light incident upon
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the mirror and transmltted through mirror glass 8. The
: ~ assembly also includes a solenoid coil 16 which i~ energi~ed
in response to light inc~ident upon~th~ mirror above a prede*er-~:
mined intensity, the coil co-acting with a magnetic member 18
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carried by th~ mirror glass to move -the mirror gla~s from i-ts
normal position to an anti-glare pOSitiOtl when the solenoid
is energlzed. The mirror glas3 is held in its rlormal
position in normal opera-tion by means of a return spring 20.
The mirror is mo~lnted to the motor vehicle by means of a
mounting arm 22 a-ttached to -the rear of the housing 2.
Referring now in more detail to the construction of -the
housing, back pla*e ll is in the form of a tray wi-th rear
walls 30 (Figure 4) tapering to provide a deepened portion a-t
the centre of the tray. Reinforcing ribs 32 are provided
for strengthening the tray and the centre of the *ray carries
three fixing studs 34 to retain the electrical assembly 12.
The rear of the back plate provides a socket 36 of a ball and
socket joint which serves -to receive a ball member 38 of
mounting arm 22. Mounting arm 22 is thus held mounted to
~ back plate 4 by means of a universal ball and socket joint.
; Socke* 36 i9 designed to permit various configurations of
mounting arms having different size end portions to be mounted
to the back plate. Referring to the construction of socket
36 as ~hown in Figure 4, a boss portion 40 at the rear of the
back plate has a vertical bore 42 of circular section which
communicates with a slot 44 in the surface of the bos~to
permit the mounting arm 22 to extend from the bore 42. Th0
top portion of the bore 42 is tapered as at 46 to permit
ball joints of different sizes to make a good fit with the
bore. This may occur where a motvr vehicle has already
installed an appropriate mounting arm. A locking member 48
i~ provided having a cylindrical portio~50 making a rea~onably
cloqe fit within bore 42 and having a recessed top portlon 52
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providing a seat for ball 38. Locking member ~8 is locked
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in posltion by means o:f two self ta~pping screws 5/t extending
through apertures 56 in w:ing portions 58 of locking member 48.
Wing portions 58 are arranged to fi-t within recesses 60 of
boss 40 and screws 54 extend into the interior of back plate
4 to extend through registering apertures 62 in a reinforcing
rib 32. Apertured spring steel clips 64 are mounted over
apertures 62 in order to receive screws 54 and to engage the
threads thereof so that screws 54 can be tightened to secure
the iocking member 48. The top of boss 40 has a ribbed
surface 66. Mounting artn 22 shown has a ~`lat su.rface 70
which may be adhesively mounted by means of an adhesive pad
to the window of a motor vehicle. Reinforcin$ ribs 72 are
provided on the other side of surface 70 in order to streng-then
the surface and to prevent warping.
The front surface of back plate member 4 has at its base
an aperture 80 through whioh part of the electrical assembly,
a sensitivity adjustment thumb-wheel 82, projects. The
: front surface of back plate 4 has apertures 84 spaced around
the surface which serve in the securing of the front frame 6
to back pla*e 4.
Front frame 6 i~ generally rectangular in configuration
and pos~esses projecting nodules 86 around its periphery which
; in*erengage with recesses 84 in back plate 4 as a snap fit
: in order to secure together back plate 4 and front frame 6.
Front frame 6 has a recessed portlon 88 in order to rece1ve
, : mirror glass 8. A further recessed portion 90 extends along
the lo~er edge of the front of back plate 4 and co-operates
: w1th recess 88 i.n order to provide a longitudinal U-shaped
reces~-. This U-shaped recess serves to support the lower
edge of ~irror glass 8 and to permit the mirror glass to
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pivot about pivot lO. As ~n al-ternatlvc arrangement, recess
o8 and recess 90 may be sh~ped to provide a recess ci~cular
in section and a cylindrical element may be provided to fit
within the recess and to support the mirror glass 8, the lower
edge of the mirror glass fit-ting within an axial slot in the
cylindrical element.
Mirror glass 8 is of conventional construction. Mirror
glass 8 is only part,ly s:ilvered in the region 100 opposite
cby providing a series_of transparent lines~
photosensor 14lin order to permi-t incident light to be -trans-
mitted through the mirror to photosensor 14. This arrangementprovides a collimation effect for light passing through the
mirror onto photosensor 14 and this renders the mirror more
sensitive to light from headlamps of vehicles behind the
motor vehicle containing the rear view mirror as compared
wlth other lights for examp-le courtesy lights within the
motor car or street lighting.
The electrical assembly 12 i3 formed as a ~ingle unit
and includes a board 104 upon which the other elements of
the assembly are mounted. The board has apertures registering
with Ytuds 34 in order to secure the assembly to back plate 4.
Locki~g clips 106 are provided to fit on studs 34. The
~- as~embly is po~ered from a suitable circuit (e.g. sidelight
circuit) energized by the vehicle battery and leads will be
fed through the back plate 4 in a suitable manner. Photo-
sensor 14 which may comprise a photodiode is connected (see
igure 5) to a potentiometer in the form of a thumb-wheel~82
which regulates the sensitivity of the electrical asse~bly,
i.e. the thumb-~heel 82 predetermines the i~tensity of llght
.
incidsnt upon the photosensor 14 at which the electrical
a~embly will b~e actuated to moYe the mirror to the anti-~
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glare position. The movable contact 106 of th-~nb-wheel 82
is connected by a series resistance 108 and a reverse biased
diode 110, connected between resistor 108and ground, to the
base of a transistor 112. The collector ci,rcuit of tran-
~istor 112 includes solenoid coil 16. A protection diode
114 is connected across solenoid coil 16. Solenoid coil 16
has a centre tapping which iq connected to contacts 116,
Contacts 116 are closed when glass 8 is moved to
the anti-glare position and are shown schematically in Figures
2 and 3.
As can be seen in Figures 2 and 3 the physical disposi-
tion of the electrical assembly is such that the core
of the solenoid 16 is disposed remote Prom magnetic member
18 in the normal rest position of the mirror. Magnetic
member 18 is secured to the rear of mirror glass 8 by means
of an adhesive pad 120 and the mirror glass is retained in
the rest position by a return spri.ng 20 coupled between an
aperture in a depending tine 122 of magnetic member 18 and
a tine 124 of an upstanding member 126. The edge 128 of
member 126 remote from board 104 ha~ a recess 130 to receive
tine 122 which engages the base of the recess in order to
provide said pivat 10 for the mirror.
Pads 140 adhesively secured to the mirror gla~4 8 are
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arranged to engage reinforcing ribs as at 142 in order to
25 ~ provide a buffer when mlrror glass 8 moves to the anti-glare
~;: position. ,
In operation of the rear ~iew mirror light from headlamps
of a vehicle approaching the motor vehisle in which t~e rear
yiew mirror lS mounted may cause light to be incident upon the
~30 ~ rear view mirror and this .,
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light will be transmitted to the photoserlsor 14. -If the
intensity of the light is above a Level determined by the
setting of potentiometer 82, sufficient current will be
generated in re~istor 108 to switch transi~tor 110 from it~
normal non-conductive s-tate to a fully conductive state.
This causes energizing current to flow in the solenoid 16,
which creates an electromagnetic field to attract magnetic
member lo and to thus move mirror glass 8 about pivot 10 to
the anti-glare position (Figure 3) -in which the amount of
light reflected from the mirror glass to the driver of the
vehicle is reduced. Now the amount of current required to
flow in the solenoid coil to move the mirror to the anti-
glare position is considerably more than that required to hold
the mirror in the anti-glare position. Accordingly when
mirror glasq 8 moveq to the anti-glare position, contacts
116 are closed which has the effect of shorting out part of
coil 16 and thus causinga reduced current flow in the sole-
noid. This current flow is sufficient to hold the mirror
glass in *he anti-glare position for as long as light above
th~ predetermined intensity shines on the mirror glass.
Reduction of the current flow through the ~olenoid coil
permits a longer life eYpectancy for the components of the
circuit assembly.
In the aIternati~e form of electrical assembly shown in
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Figure 6, parts qimilar to those of Figure 5 are indicated
by similar ref~rence numerals. Transistor 112 serves to
amplify the cur;rent generated in resistor 108 and a main switching
~ transi~tor 150 is coupled to th0 collector circuit of tran-
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sistor 110 via resi~tors 152, ~154 and diode 156. Coil 16
is connected ~n the collect~r circuit of transistor 150
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-together with a series res:is-torl58. Contact~ 116 which are
closed in the normal position of mirror gla~s 8 are
connected across resistor 158. 'I`his alternative form has a
higher sensitivity to incident light by virtue of the ampLi-
fication provided by transistor 110~ When the coil 16 isenergized to move mirror glass to the anti glare position,
contacts 116are opened so that resistor 158 is switched in-to
coil 16 in order to reduce current flow -through coil 16 and
provide a holding current.
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