GB2063661A - Rear view mirror assembly - Google Patents

Abstract

A rear view mirror assembly 10 comprises mirror 12, wiper blade 15 mounted on arm 16 for wiping the surface of the mirror 12, and a motor 22 mounted within the housing 11 supporting the mirror and arranged to drive arm 16 via screw 19 and carriage 18. The screw may have oppositely-handed helical grooves thereon and be so arranged that it drives the carriage back and forth along it. Alternatively, the carriage 18 may be driven by a single-handed lead screw, the direction of rotation of the motor being reversed each time the wiper blade 15 reaches the end of a sweep across the mirror 12. The assembly may include means for heating the mirror. <IMAGE>

Description

SPECIFICATION Rear view mirrors This invention relates to rear view mirrors.

According to the present invention there is provided a rear view mirror assembly comprising a mirror, a hollow body supporting the mirror, a wiper for wiping at least part of the viewed surface of the mirror, drive means including a motor driven lead screw mounted within the hollow body, and a driving connection between the lead screw and wiper for moving the wiper over the mirror surface in response to rotation of the lead screw.

Said drive means may further include means to cause the wiper to be moved back and forth over the mirror.

In this latter case, the lead screw may have oppositely-handed helical grooves extending over a common portion of the screw, the driving connection having a follower for following one or the other of the helical grooves to move the driving connection back and forth along said common portion of the screw, and the screw further having means at each end of the common portion of the screw to redirect the follower from one of the helical grooves to the other. Each redirecting means preferably comprises an abutment facing along the lead screws.

Alternatively, the lead screw may have a singlehanded thread extending along the screw, the driving connection having means to engage the thread so that rotation of the screw in one direction or the other causes the driving connection to be driven along the screw in one direction or the other, respectively, and the drive means further including means to reverse the direction of rotation of the lead screw when the driving connection reaches one or the other of a pair of spaced locations along the lead screw. The motor is preferably a reversible electric motor, in which case the reversing means may include an electrical circuit for reversing the polarity of electrical supply to the motor.

The wiper preferably comprises a wiper arm extending across a part of the surface of the mirror and a wiper blade mounted on the wiper arm, the wiper arm being connected to the driving connection so that the wiper blade is held against the surface of the mirror.

The body may have a slot extending generally parallel to, or along, an edge of the body, the driving connection comprising a carriage mounted on the lead screw within the body and a cantilever extending from the carriage through the slot so that movement of the carriage along the lead screw causes movement of the cantilever along the slot, the wiper being mounted on the free end of the cantilever.

Means may be provided for parking the wiper at one edge of said viewed surface or said part of the viewed surface of the mirror.

The assembly may further include means for heating the mirror.

A specific embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a partly cut away front view of a rear view mirror a carriage of which is shown in both its operative and its parked positions; Figure 2 is a view from below of Figure 1; Figure 3 is a view on the arrow A of Figure 1; Figure 4 is an enlarged view of the area designated X in Figure 1; Figure 5 is a cross-sectional view of Figure 4 along the line Y-Y; and Figure 6 is a circuit diagram of the power supply to a motor of the mirror shown in Figure 1.

Figure 7 is a view similar to Figure 1 of a modified rear view mirror according to the invention; Figure 8 is a circuit diagram for the mirror illustrated in Figure 7; and Figure 9 illustrates a modification of the mirror shown in Figure 7.

Figures 1-3 show a rear view mirror, generally indicated at 10, having a generally rectangular cross-section body 11. The body 11 is generally in the form of a box and has a mirror 12 mounted in the open mouth 13 thereof by means of a sealing strip 14.

A wiper blade 15 is supported to extend across the width of the mirror 12 by means of arm 16. As can be seen in Figure 3, the connection 17 between the wiper blade and arm 16 is a pivotable connection.

The arm 16 is in turn mounted on the body by means of a carriage, generally indicated at 18, which is in turn mounted on a double helical screw 19 which is mounted on the body 10 to extend across the greater part of the length thereof and parallel to the adjacent side of the body 11.

The screw 19 is rotatably mounted in this position by a pair of spaced upstanding flanges 20, formed by the ends of a plate 21, which is secured to the base of the body 11. A motor 22 is also secured to one flange 20 and is drivingly coupled to the screw 19 by means of a geartrain 23.

The carriage 18 includes a generally cylindrical body 24 which encircles the screw 19 and is supported thereon by bearing sleeves 25. The body 24 carries a pivot pin 26, which in turn supports an elliptical shoe 27 to project inwardly of the body 24 to locate in a groove 28a of double helical groove 28 of screw 19.

The body 24 supports, at its lower end, a generally L-shaped cantilever 29 which extends through an elongate slot 30 in the lower edge of the body 11.

The cantilever 29 is formed with a pair of spaced flanges 31, between which flanges is pivotably mounted the arm 16. A spring 32 engages the arm 16 adjacent its mid-point and is further mounted on the cantilever 29 adjacent its free end. The spring urges the arm 16 towards the mirror 12 so that the wiper blade 15 is held in engagement with the mirror 12.

A generally U-shaped plate 33 is mounted on the base of the body 11 to carry a pair of spaced reaction rollers 34. The rollers 34 are disposed relative to the body 24 to prevent the body 24 tilting under the action of spring 32.

The drawing(s) originally filed wasiwere informal and the print here reproduced is taken from a later filed formal copy.

In use, power is supplied, via lead 36 (see Figure 6) to the motor 22. The motor is thus caused to rotate the screw 19 via gear train 23. As the screw 19 rotates the shoe 27 is driven along the groove 28, and hence the body 24 and its cantilever 29 are dri ven axially along the rotating screw 19. This axial movement of the carriage 18 causes corresponding movement of the arm 16 and hence the wiper blade 15. The wiper blade 15 therefore wipes across the area of the viewed surface of the mirror 12 indicated in chain line at 37.

Referring to Figure 4 when the shoe 27 reaches an end of the groove 28, the direction of the shoe is reversed by curved groove portion 38 and the shoe then enters the other groove 28b of the double helical groove 28 and the direction of movement of the carriage 18 is reversed. This reversal happens at each end of the screw 19 until the supply power to the motor is stopped. Thus it will be appreciated that the blade 15 is swept backwards and forwards over the area delineated by line 37.

Referring now to Figures 1 and 6 a two-way switch generally indicated at 39 is located at the opposite end of screw 19 to the motor 22. The switch 29 consists of two spaced contacts 40 and 41 and a central moveable contact 42, which is generally urged into contact with contact 40. Contact 42 has a downwardly extending projection 43, which is arranged to engage the body 24 as the body 24 moves into its right-hand-most position. The movement of the body 24 into its right hand most position urges the contact 42 out of engagement with contact 40 and into engagement with contact 41.

As will be seen in Figure 6, the motor 22 is connected to earth by a lead 35 and to the moveable contact 44 of a two-way switch 45 via a lead 46 and a diode 47. One contact 48 of a switch 45 is connected to earth, whilst the other contact 49 is connected to a source of positive potential, by lead 36. Contacts 40 and 42 are connected so that when engaged they short circuit the diode 47, whilst contacts 42 and 41 are connected such that when they are connected the lead 36 is connected to the motor 22 whatever the position of the switch 45.

When the wiper is to be used the moveable contact 44 of switch 45 is connected to contact 49 and hence the motor 22 is connected between the source of positive potential and earth and it drives screw 19.

At the time the body 24 reaches its right-hand-most position the contact 42 is moved out of engagement with contact 40 and into engagement with contact 41. As the lead 35 is directly connected to the motor via switch 45 this movement has no effect.

When, however, it is desired to stop the wiper blade 15 the moveable contact 44 is switched over into connection with contact 48. If the body 24 is anywhere other than in the right-hand-most position the movement of this switch initially has no effect, because the lead 36 is still connected to the motor 22 by means of contacts 41 and 42. However, as the body 24 moves into its right-hand-most position the contact 42 is pushed into connection with the contact 40, disconnecting the motor from its positive source of potential and connecting it via the contact 40 and 42 to earth. This short circuiting of the motor causes the back e.m.f. in the motor to be reduced substan tially to zero and so the motor is braked very quickly.

The carriage 18 is therefore stopped in its parked position as shown at 50 in Figures 1 and 2 and hence the wiper blade 15 and arm 16 are held in a position where they do not obscure an important part of the viewed surface of mirror 12.

It will be appreciated that the double helical screw could be replaced by a single screw if the motor 22 was a reversing motor. An example of such an arrangement will now be described with reference to Figures 7 and 8.

Referring firstly to Figure 7, there is shown a mod ification of the mirror shown in Figures 1 to 6 and like parts have been alloted the same reference numer als. The main modification is that the lead screw 19 has a single-handed thread which is engaged by co-operating threaded element or nut 52 mounted on the carriage 18. The drive motor 22 for the lead screw has a reversible drive effected by reversing the polarity of the voltage applied across the motor.

Thus, by periodically reversing the motor the direction of motion of the carriage 18 and with it the wiper blade along the lead screw 19 can be reversed.

The control circuit for the motor is shown in Figure 8 and includes a double-pole limit switch having two normally-closed poles 62A and 62B respectively disposed at the right hand end of the lead screw 19 such that, when and only when the carriage 18 is in its right-hand-most position, the poles 62A 62B are open. Furthermore, a single-pole normally-open limit switch 64 is disposed at the left hand end of the lead screw 19 such that, when and only when the carriage 18 is in its left-hand-most position, the switch 64 is closed.

The right and left limit switches and the motor 22 are connected in circuit with an on-off/park switch 60, a double-pole changeover relay, having a coil 68 and changeover switches 70A, 70B, and a diode 66 in the manner shown in Figure 8.

The relay changeover switches 70A, 70B are connected so that they can reverse the polarity of the voltage applied across the motor 22. The left limit switch 64 is connected so that, when the carriage 18 reaches the left-hand-most position, the relay coil 68 is activated to operate the changeover switches 70A, 70B. The pole 62B of the right limit switch is connected so as to latch the relay 68, 70A, 708 until the carriage 18 returns to the right-hand-most position, the diode 66 preventing a momentary short circuit of the power supply at the instant when the left limit switch 64 is closed. The other pole 62A of the right limit switch is connected in parallel with the onoff/park switch 60, so that when the on-off/park switch 60 is moved to its "off/park" position, the motor 22 keeps running until the carriage 18 has returned to its right-hand-most position, i.e. its parked position. Thus, as with the embodiment shown in Figures 1 to 6, when the on-off/park switch 60 is moved to its "on" position, the wiper blade 15 is swept from side to side across the mirror 12, and when the switch 60 is returned to its "off/park" position, the wiper blade 15 continues to be swept across the mirror 12 until it reaches its parked position.

Figure 9 illustrates a further modification, wherein the motor 22 drives the lead screw 19 via a worm 80 mounted on the motor shaft engaging a wormwheel 82 mounted on the lead screw 19. This latter modification may, of course, be applied to the embodiment illustrated in Figures 1 to 6.

The provision of a wiping mechanism for a rear view mirror is particularly useful during misty or cold weather. In countries where temperatures are commonly sub zero it is often a requirement that the mirror be heated. However, because of the construction of the mirror it is often difficult to put sufficient heat into the mirror to melt significantly the ice formed thereon. Even if the ice is melted, considerable misting occurs.

It will be appreciated that the provision of a wiper will remove the problem of misting and in addition will serve to free the ice as any melting occurs and therefore greatly enhance the chances of the heating element successfully clearing the mirror of ice.

Claims (11)

1. A rear view mirror assembly comprising a mirror, a hollow body supporting the mirror, a wiper for wiping at least part of the viewed surface of the mirror, drive means including a motor driven lead screw mounted within the hollow body, and a driving connection between the lead screw and wiper for moving the wiper over the mirror surface in response to rotation of the lead screw.

2. An assembly as claimed in claim 1, wherein said drive means further includes means to cause the wiper to be moved back and forth over the mirror.

3. An assembly as claimed in claim 2, wherein the lead screw has oppositely-handed helical grooves extending over a common portion of the screw and the driving connection has a follower for following one or the other of the helical grooves to move the driving connection back and forth along said common portion of the screw, the screw further having means at each end of the common portion of the screw to redirect the follower from one of the helical grooves to the other.

4. An assembly as claimed in claim 3, wherein each redirecting means comprises an abutmentfacing along the lead screw.

5. An assembly as claimed in claim 3, wherein the lead screw has a singe-handed thread extending along the screw and the driving connection has means to engage the thread so that rotation of the screw in one direction or the other causes the driving connection to be driven along the screw in one direction or the other, respectively, the drive means further including means to reverse the direction of rotation of the lead screw when the driving connection reaches one or the other of a pair of spaced locations along the lead screw.

6. An assembly as claimed in claim 5, wherein the motor is a reversible electric motor and the reversing means includes an electrical circuit for reversing the polarity of electrical supply to the motor.

7. An assembly as claimed in any one of the preceding claims, wherein the wiper comprises a wiper arm extending across a part of the surface of the mirror and a wiper blade mounted on the wiper arm, the wiper arm being connected to the driving connection so that the wiper blade is held against the surface of the mirror.

8. An assembly as claimed in any one of the preceding claims, wherein the body has a slot extending generally parallel to, or along, an edge of the body, the driving connection comprising a carriage mounted on the lead screw within the body and a cantilever extending from the carriage through the slot so that movement of the carriage along the lead screw causes movement of the cantilever along the slot, the wiper being mounted on the free end of the cantilever.

9. An assembly as claimed in any one of the preceding claims, further including means for parking the wiper at one edge of said viewed surface or said part of the viewed surface of the mirror.

10. An assembly as claimed in any one of the preceding claims, further including means for heating the mirror.

11. A rear view mirror assembly substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 6 of the accompanying drawings or Figures 1 to 6 as modified by Figures 7 and 8 and/or as modified by Figure 9 of the accompanying drawings.