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MOTOROLA INC. Technical Developments Volume 17 December1992
APPARATUS HAVING A LIGHT SOURCE FOR ACTIVATING LUMINOUS CONTROLS AND DISPLAY BACKLIGHT
by Joseph E. Laviana
Under adverse lighting conditions, a pager's user input controls may be difficult to locate, resulting in the user grappling at the device to find the desired controls. A need exists for a pager having ilhuninated controls with minimal current drain regardless of available ambi- ent light.
DETAILED DESCRIPTION OF THE INVENTION
Referring to Figure 1 a selective call receiver 10 includes an antenna 12 and a receiver 14 for generally receiving transmitted selective call addresses and mes- sage information. The selective call receiver 10 also includes a microcomputer 20 coupled to an optional annunciator apparatus 18 for tone and voice messages, a battery 22, a control apparatus 16 such as &/off, vol- ume control, and display control switches, and a display 24 for displaying message and control information as is well known to those skilled in the art. A light source 26 such as a light emitting diode (LED) is also included for ilhuninating the controls 16 and/or the display 24 of the selective call receiver 10 by generating a light pulse 25 and 27, respectively. The light source 26 may comprise a variety of light sources such as an incandescent lamp, without deviating from the intent ofthe invention.
Referring to Figures 2 and 3, the selective call receiver 10 is placed in a housing 28 such that the controls 16 and the display (e.g., liquid crystal display) 24 are exposed to the user. In the preferred embodiment, the controls 16 comprise a reset button 36 having a phosphorescent coated surface 30 and a visual alert 32. In addition, the display 24 also comprises a phosphorescent coated SW face 34. The reset button 36 and display 24 should corn- prise a translucent material to enable the phosphores- cent surfaces 30 and 34 to be visible at outer surfaces 38 and 40, respectively, after being charged. This material may comprise a translucent polycarbonate such as Gen- eral Electric's Lexan 14 1. Both the reset button 3 6 and the display may comprise a variety of materials which are capable of transmitting the luminescence provided by the charged phosphorescent surfaces 30 and 34, with- out deviating from the intent of the invention.
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In the preferred embo...
