Patent Application
20170101059
The present invention generally relates to a display mirror assembly for a vehicle.
As shown in
According to one aspect of the present invention, a display mirror assembly for a vehicle is provided comprising a mirror element having a front surface and a rear surface, wherein the mirror element has a refractive index RM at the rear surface of the mirror element; a display having a front surface and a rear surface where the display is positioned behind the mirror element such that the front surface of the display is spaced apart from the rear surface of the mirror element, wherein the display has a refractive index RD at the front surface of the display; and an optical medium disposed between, and in contact with, the front surface of the display and the rear surface of the mirror element, the optical medium having a refractive index of RO between about ±10% RD and ±10% RM.
According to another aspect of the present invention, a display mirror assembly for a vehicle is provided comprising a mirror element having a front surface and a rear surface, wherein the mirror element has a refractive index RM at the rear surface of the mirror element; a display having a front surface and a rear surface where the display is positioned behind the mirror element such that the front surface of the display is spaced apart from the rear surface of the mirror element, wherein the display has a refractive index RD at the front surface of the display; and an optical bonding layer disposed between, and in contact with, the front surface of the display and the rear surface of the mirror element, for bonding the mirror element to the display. The optical bonding layer has a refractive index of RO between about ±10% RD and ±10% RM.
According to another aspect of the present invention, a method of making a display mirror assembly is provided where the method comprises: providing a mirror element having a rear surface; providing a display having a front surface; and bonding the front surface of the display to the rear surface of the mirror element using an optical bonding layer disposed between, and in contact with, the front surface of the display and the rear surface of the mirror element, wherein the mirror element has a refractive index RM at the rear surface of the mirror element, the display having a refractive index RD at the front surface of the display, and the optical bonding layer having a refractive index of RO between about ±10% RD and ±10% RM.
These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The present illustrated embodiments reside primarily in combinations of method steps and apparatus components related to a display mirror assembly, particularly one adapted for use as a vehicle rearview assembly. Accordingly, the apparatus components and method steps have been represented, where appropriate, by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Further, like numerals in the description and drawings represent like elements.
For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in
The terms “including,” “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.
Referring now to the drawings, reference numeral 10 generally designates a display mirror assembly for a vehicle. As shown in
Optical bonding layer 15 may be formed of a material that has a refractive index that is substantially the same as that of one or both of rear substrate 11 of mirror element 12 and display 18 and a polarizer that may be disposed on the forward most surface of display 18. In general, the refractive index of optical bonding layer 15 should be within 10% of that of the display 18 and mirror element 12 to keep reflectance within 0.5% or less at the surface interfaces. In other words, where the mirror element 12 has a refractive index RM at the rear surface 11a of the mirror element 12 and the display 18 has a refractive index RD at the front surface 18a of the display 18, the optical bonding layer 15 has a refractive index of RO between about ±10% RO and ±10% RM. The closer the refractive index is the better. In prior constructions as shown in
As noted above, optical bonding layer 15 also serves to bond the mirror element 12 to the display 18. The large surface area over which optical bonding layer 15 forms this bond provides a much more rigid bond than prior designs. In fact, it is believed that by supporting display 18 within the mirror housing 30 (
Use of optical bonding layer 15 further provides greater electrical efficiency since greater optical transmission through mirror element 15 means that the backlight of display 18 does not need to be driven as hard to produce a given brightness level through the mirror element. Thus, less electrical power is needed to obtain the same optical performance levels.
Also, the visual appearance of the display mirror assembly is improved at night by using optical bonding layer 15. Previously, the polarizer material used in the current display has an anti-glare coating that has a haze that scrambles the reflected image. In the absence of such an anti-glare coating, the display otherwise has to be perfectly parallel to the rear surface of the mirror element, and even then there still might be a concern with double imaging. When optical bonding layer 15 is used to reduce reflection from display 18, the anti-glare coating is not needed on the polarizer. Elimination of the anti-glare coating improves the appearance of the display mirror assembly at night. Further, the anti-glare coating also reduces transmission so elimination of this coating further increases transmission.
The optical bonding layer 15 between the display 18 and mirror element 12 can be made with a variety of materials. The primary characteristics are transparency, suitable refractive index, bonding strength, and durability to moisture and temperature extremes. Optically clear adhesives are available in liquid and film form. Liquid optically clear adhesives (LOCAs) are available in a wide range of chemistries, viscosities, and curing mechanisms. LOCAs are typically 100% solid formulations based on silicone, epoxy, acrylic, or acrylated urethane chemistries and are available in a wide range of viscosities to meet application requirements. Higher viscosity formulations are often used as a dam to control the placement of lower viscosity fill formulations, which easily conform to the display and mirror element substrates. LOCAs are usually precisely pressure dispensed, but other methods such as slot die coating could also be employed. The LOCAs can be cured thermally, with ultraviolet (UV) light, and UV/moisture dual cure mechanisms. Examples of suitable LOCAs include the DELO-PHOTOBOND® and DELO-DUALBOND® series available from DELO Industrial Adhesives (Windach, Germany). Other examples of suitable LOCAs include Loctite 3196 and Loctite 5192 available from Henkel AG and Co. (Dusseldorf, Germany) and the 9700-Series available from Dymax Corporation (Torrington, Conn.). Similar materials are available from other suppliers. An advantage to using a wet process to form optical bonding layer 15 is that it can accommodate more tolerance for a lack of flatness of mirror element 12 and display 18. Optically clear adhesives (OCAs) in film form, also known as optically clear film adhesives, optically clear pressure sensitive adhesives, or optical interlayers, are available in a variety of chemistries and are typically used in lamination processes using heat, vacuum, and pressure to bond the substrates. The film forms are based on acrylic, aliphatic thermoplastic urethanes (TPU), ethylene vinyl acetate (EVA), ionoplast, or polyvinyl butyral (PVB) chemistries. Examples of suitable film-based optically clear adhesives are OCA 8142 and OCA 9483 available from 3M (St. Paul, Minn.). Similar materials are available from other suppliers. Optical bonding services using film-based optically clear pressure sensitive adhesives are available for display to mirror element bonding through Rockwell Collins (Cedar Rapids, Iowa). Other companies offer similar bonding services.
As shown in
Referring generally to
The display 18 may be generally planar, with outer edges defining a front surface. The front surface of the display 18 can be shaped to correspond to and fit within the shape of the viewing area 40 of the display mirror assembly 10. As illustrated in
By way of explanation and not limitation, in operation, the display mirror assembly 10 can be used as a full display mirror in a vehicle to be operational substantially continuously while driving, as opposed to back-up display systems that are used only during certain times of vehicle operation (i.e., when the vehicle is in reverse gear).
Although mirror element 12 is shown in
Display mirror assembly 10 may optionally include an actuator device 33, as shown in
Additionally, to provide information to the viewer of the display mirror assembly 10, the display mirror assembly 10 may include information regarding the field of view 17, such as a partially transmissive graphic overlay or an image on the display 18 visible on the viewing area 40 when the display 18 is in use.
The above description is considered that of the preferred embodiments only.
Modifications of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and not intended to limit the scope of the invention, which is defined by the claims as interpreted according to the principles of patent law, including the doctrine of equivalents.
This application claims priority to and the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 62/240,634, filed on Oct. 13, 2015, entitled “VEHICLE DISPLAY MIRROR ASSEMBLY HAVING IMPROVED EFFICIENCY,” the entire disclosure of which is hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62240634 | Oct 2015 | US |
