1. Field of the Invention
The invention relates to a glass substrate created to have more than one type of surface. More particularly, the invention relates to a glass substrate to be used in an external rearview mirror of a motor vehicle wherein the glass substrate used to create the mirror surface includes a primary mirror surface and a blind spot mirror surface.
2. Detailed Description of the Related Art
Blind spot mirrors are common for exterior external rearview mirrors on motor vehicles, wherein the exterior rearview mirror assembly includes a primary reflector, also known as the Main Viewing Glass, and a secondary reflector also known as a Blind Spot Mirror. Automotive manufacturers often provide these blind spot mirrors on the vehicles sold because it is well known that a “blind zone” or “blind spot” exists on the side of most vehicles.
In some instances, this secondary mirror is mounted separately from the primary reflector and thus is independently adjustable from the main viewing glass. In other cases, the secondary reflector is mounted on the same carrier, or backing plate, as the primary reflector. In still another embodiment, the blind spot mirror is a concave depression on a second surface of the primary reflector within the exterior rearview mirror. While this last concept has been well established through prior art and has been so, for some time now, this embodiment is not prevalent within the marketplace because of the extreme difficulty realized in manufacturing the concave depression in the glass substrate.
A method for creating a concave section of glass from a glass substrate having flat surfaces includes the use of a grinding wheel and a turntable. The method includes the steps of securing the glass substrates to the turntable. The turntable is then spun to create a turntable axis of rotation. The grinding wheel is rotated about a wheel axis of rotation such that the wheel axis of rotation is perpendicular to the turntable axis of rotation. The grinding wheel and the turntable move relative to each other along the turntable axis of rotation. The glass substrate is ground by the grinding wheel contacting the glass substrate to create the concave section of glass while the glass substrate is rotating about the wheel axis of rotation and moving relative to the turntable.
Advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
The invention is a method for creating a glass substrate 10 having at least one surface which is complex. The glass substrate 10 is to be used in an exterior rearview mirror assembly, as is generally indicated at 12 in
Extending out from the pivot 18 and into the mirror case 16 is a support structure 26. The support structure 26 is fixedly secured to the mirror case 16. In many instances, the support structure 26 may be integral with the mirror case 16. A motor 28 is secured to the support structure 26. The motor 28 is electrically connected to remote switching mechanisms in the passenger compartment to receive control signals from the driver of the motor vehicle to adjust the orientation of the glass substrate 10 with respect to the position of the driver. The electrical connections between the motor 28, the remote switching, and power are not shown but are well known to those skilled in the art.
A backing plate 30 is fixedly secured to a movable portion of a motor housing 32 that moves with respect to the rest of the motor 28 and the support structure 26. More specifically, the motor 28 moves the portion of the housing 32 based on the control signals it receives. The backing plate 30 is secured to the portion of the housing 32 that moves such that there is no lost motion therebetween. The backing plate 30 is used to secure the glass substrate 10 to the motor 28 and hold the glass substrate 10 in the desired orientation.
The glass substrate 10 is secured to the backing plate 30 with an adhesive (not shown). The glass substrate 10 includes a first surface 34 and a second surface 36. In the embodiment shown, the first surface 34 is planar and transparent. The second surface 36 is substantially planar and parallel to the first surface 34. The second surface 36 includes a reflective coating (not shown) that is applied to the glass substrate 10 prior to the adhesive being applied between the backing plate 30 and the second surface 36. The reflective coating allows the driver of the motor vehicle to see objects rearward of the exterior rearview mirror assembly 12 without having to see the backing plate 30 or the interior 38 of the mirror case 16 and all that it contains.
The second surface 36 of the glass substrate 10 is complex in that it has more than one type of viewing surface. More specifically, the second surface 36 includes a primary reflective surface 40 and a secondary reflective surface 42. The primary reflective surface 40 is planar and parallel to the first surface 34 of the glass substrate 10. The secondary reflective surface 42 is convex and smaller than the primary reflective surface 40. The secondary reflective surface 42 is commonly referred to as a blind spot or blind zone mirror. While the secondary reflective surface 42 may be located anywhere with respect to the primary reflective surface 40, it is shown in the upper left hand corner of the glass substrate 10 as viewed by the driver of the motor vehicle. The secondary reflective surface 42 is created prior to the coating of the second surface 36 with reflective coating. Therefore, it has the same reflective qualities as the primary reflective surface 40.
Once the concave surface 44 has been created, the concave surface 44 is polished. The polishing of the concave surface 44 may include a very fine grit abrasive material. In addition, the step of polishing may include a slurry that may include cerium oxide. The step of polishing may occur before or after the step of removing the glass substrate 10 from the turntable 46.
Referring to
To create the concave surface 44, the glass substrate 10 is secured to a turntable 46. Hooks 48 are used to secure the glass substrate 10 to the turntable 46. Devices similar to hooks 48 may be used. In addition, a vacuum may be applied to the glass substrate 10 from the turntable 46 to secure the glass substrate 10 thereto. The turntable 46 is spun to create a turntable axis of rotation 50. As shown in
Disposed adjacent the turntable is a pillar 58. The pillar 58 is stationary with respect to the turntable 46. The pillar 58 represents a stationary structure from which a grinding wheel 60 will move in relation thereto. It should be appreciated by those skilled in the art that the pillar 58 may be replaced with another structure that provides a support for the movement of the grinding wheel 60 with respect to the turntable 46. By way of example, the pillar 58 may be replaced with a base located remote from the turntable 46, whereby a robot arm would extend from the base to position the grinding wheel 60 in the appropriate position with respect to the turntable 46.
The pillar 58 includes two channels 62, 64 through which a grinding wheel motor 66 is secured. The channels 62, 64 provide the grinding wheel 66 with the ability to move up and down, as represented by arrow 68 (the directions up and down are used for purposes of the relationships shown in the Figures and are not to be interpreted as limiting). The grinding wheel 60 also moves up and down in the directions defined by arrow 68. The grinding wheel 60 moves, however, along the turntable axis of rotation 50 such that when it is moved far enough, it engages the glass substrate 10 at a point where the turntable axis of rotation 50 intersects the glass substrate 10. The grinding wheel motor 66 includes an output shaft 70 that is fixedly secured to the center 72 of the grinding wheel 60. Therefore, the grinding wheel 60 rotates about an axis 74 that is defined by the output shaft 70 of the grinding wheel motor 66. As it may be appreciated by those skilled in the art, the grinding wheel 60 may be indirectly driven by the grinding wheel motor 66.
The grinding wheel motor 66 spins the grinding wheel 60 in a direction represented by arrows 76. The grinding wheel is spun at speeds in a range between 3,000 rpm and 5, 000 rpm. In the preferred embodiment, the grinding wheel 60 is spun at a rate of 4,000 rpm.
Once the turntable 46 and the grinding wheel 60 are spinning at their appropriate speeds, the grinding wheel 60 is moved downwardly, the grinding wheel 60 engages the glass substrate 10. The spinning motions of the grinding wheel 60 and the turntable 46 allow the grinding wheel 60 to grind a concave surface 44 out of the second surface 36 of the glass substrate 10. In this way, the grinding wheel 60, having a defined radius, produces a concave section of glass having a concave surface 44 with a radius of curvature equal to the radius of the grinding wheel 60.
Referring now to
The grinding wheel 160 and the turntable 146 rotate at speeds comparable to those described above. The advantage of using the grinding wheel 160 at an acute angle with respect to the turntable axis of rotation 150 is that the grinding wheel 160 may have a radius that is smaller than the resulting radius of curvature of the concave surface 144 being created by the grinding wheel 160. By way of example, the radius of the grinding wheel 160 may be in the range of ⅖th the size of the radius of curvature of the resulting concave surface 144. In this embodiment the grinding wheel 160 moves up and down as represented by arrow 168 in a manner similar to that of the embodiment discussed above.
Referring specifically to
Referring to specifically to
In this embodiment, the grinding wheel 360 includes a convex outer edge 382. In addition, the grinding wheel 360 has a profile wider than that of the grinding wheel 60 shown in the preferred embodiment (
Referring to
The invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation.
Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.
This patent application is a division of U.S. patent application Ser. No. 12/697,348 filed Feb. 1, 2010, which in turn claims priority to a provisional patent application having an application No. 61/148,403, filed on Jan. 30, 2009, the specifications of which are incorporated herein expressly by reference.
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Number | Date | Country | |
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20130252514 A1 | Sep 2013 | US |
Number | Date | Country | |
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61148403 | Jan 2009 | US |
Number | Date | Country | |
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Parent | 12697348 | Feb 2010 | US |
Child | 13901694 | US |