LOW-PROFILE LCD RETAINER/MOUNT AND LIGHTPIPE
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2001-Nov-21
In a typical radio display application with backlighting, a flat lightpipe molded from clear plastic can be used to distribute light behind the LCD. This approach is likely to be used in conjunction with elastomeric connectors and a metal bezel, which clamps the LCD to a PCB.
MOTOROLA Technical Developments Volume 11 October 1990
by Todd W. Roshitsh
BACKGROUND AND PROBLEM STATEMENT
in a typical radio display application with backlighting, a flat lightpipe molded from clear plastic can be used to distribute light behind the LCD. This approach is likely to be used in conjunction with elastomeric connectors and a metal bezel, which clamps the LCD to a PCB.
The lack of space behind the LCD makes the typical approach unfeasible in many instances. For this problem, it was desired to provide an efficient method of retaining, modularizing, and backlighting an LCD within a low-profile, shock-cushioning device.
DESCRIPTION OF SOLUTION
The solution is to incorporate novel integral features into a plastic part in order to accomplish the multiple functions described above.
Figure 1 shows fmnt, side, and isometric views of the Retainer/Mount (R/M) with features numbered for reference. The device has integral cantilever-spring features (1) in the X-Y plane which lie below the LCD backplane. These features are capable of deflection in the Z-axis direction, and are located outside of the viewing area of the LCD as it exists when placed in the device. The area between the cantilevers (2) is tapered and functions as a lightpipe for LEDs positioned on the display PCB located below the lower edge (3) of the device. The lower sidewalls of the device (4) are effectively cantilever springs capable of deflection in the X-axis direction. A tapered feature (5) functions to resolve a vertical LCD insertion force into a horizontal force component, which deflects the side cantilevers outward so that the LCD can be pushed downward into place. Once the sidewall snaps back, the R/M retains the LCD in the X, Y, and Z directions. In the Z-axis, backplane cantilevers press the LCD against front retaining features (6). This provides cushioning against shock and accomodates component thickness variations in the Z-direction. The LCD is positioned in the X and Y direc- tons by wall features (7) and (6), respectively.
Once the LCD is retained within the device, features such as (9) and (10) can be used to mount the LCD to other components, such as a front shield and display PCB, respectively. These features can be tailored to meet the requirements of a given application and only one embodimen...