CA1104854A

CA1104854A - Rear view mirrors

Info

Publication number: CA1104854A
Application number: CA307,719A
Authority: CA
Inventors: Basil E. Wainwright
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-07-21
Filing date: 1978-07-19
Publication date: 1981-07-14
Also published as: IT1097250B; DK325378A; ZA784169B; EP0000653A1; AU3824078A; JPS5459734A; NO782502L; IT7825968A0

Abstract

Abstract of the Disclosure A motor vehicle rear view mirror has a mirror or glass which pivots automatically from a normal position to an antiglare position in response to headlight glare. The glass is mounted between a front frame and a back plate of a two part housing and carries a magnetic member for cooperating with a solenoid coil of an electrical assembly. The electrical assembly is formed as a single unit mounted in the back plate and includes a photosensor receiving light through a partly silvered region of the mirror glass. A signal from the photosensor is amplified by one or more transistors to energise the solenoid coil. A pair of switch contacts are actuated when the mirror glass changes its position to the antiglare position and are arranged to reduce current flow in the coil to a level just sufficient to hold the mirror glass in the antiglare position. The rear of the mirror housing is coupled to a mounting arm by a ball and socket joint, the socket comprising an elongate bore having an inwardly tapering section to receive balls of various diameters. A locking member is secured in the bore in order to retain the ball in the bore.

Description

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;
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(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 : . :
: 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 : ~ :
may occur in motor vehicles ~a~ing~mounting arms already installed~ ~ locking mem~er may ~e positioned within the ~, ~
bore after insertion of the ~all member into the ~ore in ; order ~o retain the ~all member within the bore. The locking .

: , -'. ~ , 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 ~ , 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 : : ~ 5 ~

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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 .
providing a seat for ball 38. Locking member ~8 is locked ~ ~ - 6 - -:: .

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 ~ - 7 -:-:
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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 ~ :
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 ., ;9 _ :: :
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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 . .
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-: ~ :
sistor 110 via resi~tors 152, ~154 and diode 156. Coil 16 is connected ~n the collect~r circuit of transistor 150 _ 1 0 --.

~:~ . : ' -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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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A rear view mirror for a motor vehicle, comprising (a) a housing including (1) a recessed back plate portion;
(2) a front frame portion adapted for connection with said back plate portion to define a chamber, said housing containing a recess in the inner surface of the lower portion thereof, said recess extending parallel with said front frame portion;
(b) a mirror pivotally mounted within said housing chamber, the lower edge of said mirror being arranged within said housing recess, said mirror being operable to pivot between a normal position wherein said mirror is arranged adjacent and generally parallel to said front frame portion and an anti-glare position wherein said mirror diverges from said front frame portion in the direction of the upper edge of said mirror;
(c) means for biasing said mirror toward its normal position; and (d) means for pivoting said mirror toward its anti-glare position including (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 board for detecting light inci-dent on said mirror;
(c) a solenoid coil for generating a magnetic field; and (d) transistor circuit means for energizing said coil in response to incident light on the photosensor above a predetermined intensity; and (2) metallic plate means mounted on the rear portion of said mirror opposite said electrical assembly, whereby when light above the predetermined intensity strikes said photo-sensor, said solenoid coil generates a magnetic field which attracts said metallic plate means, thereby pivoting said mirror to its anti-glare position.

2. The rear view mirror of claim 1 wherein said back plate portion and front frame portion carry mechanically inter-engaging means securing said back plate portion and said front frame portion together to define said chamber.

3. A rear view mirror as claimed in claim 1 wherein a pivot for the mirror glass is provided by a member extending from said electrical assembly and engaging co-operating means on said mirror.

4. The rear view mirror of claim 1, wherein said biasing means for biasing said mirror glass towards its normal position is spring biasing means coupled to said mirror.

5. The rear view mirror of claim 1 wherein said unitary electrical assembly includes a holding circuit which after initial energization of said coil arising from light above a predetermined intensity being incident on said photosensor acts to reduce the level of energization of the coil and includes switch contacts operated by said initial coil energization.

6. The rear view mirror of claim 1 including a mounting arm for coupling to said housing, said mounting arm providing at its free end a plane surface whereby the mounting arm may be secured by an adhesive bond to a plane surface of a motor vehicle.

7. The rear view mirror of claim 1 including a mounting arm for coupling to said housing, said mounting arm carrying a ball member engageable within a socket provided by said housing, said socket comprising an elongate bore whose diameter decreases in an inward direction, and a locking member for securing said ball member within the socket and arranged to be secured within the bore.

8. The rear view mirror of claim 7 including means for securing said locking member in said bore comprising one or more screw members engaging registering apertures in said locking member and said housing.