Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1997-12-05
2001-08-14
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S087000, C349S061000
Reexamination Certificate
active
06275211
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to computers. More particularly, it pertains to the use of waste heat in a computer system.
BACKGROUND OF THE INVENTION
Portable electronics, and in particular lap top computers, have many inherent design challenges, including decreasing package size, increasing complexity, and limited power availability. Another design challenge is the elimination of excess heat that is generated by the electronics. As individual component size decreases and device complexity increases, the amount of excess heat generated in smaller areas increases. The excess heat surrounding the components can reduce the overall life of the components.
One technique used to dissipate heat near the electronic components is to incorporate a fan for directing cooling air over a warm device. However, the use of a fan to move air through a unit is not practical since considerable power is required. Therefore, there has been extensive work in developing effective methods of moving heat from the heat generating components, for example, the CPU, to a heat dissipating component, for example, a heat sink. One such method of moving heat is a heat pipe. These devices effectively move heat from one location to another within the electronic device. However, the beat, a valuable source of thermal energy, is merely dissipated away out into the atmosphere from the electrical components and discharged as waste heat.
In order to reduce power usage for increasing battery life or decreasing battery size for portable computers, design tradeoffs are often implemented to conserve power. Various devices within a portable electronic device are not considered as critical as other devices. One tradeoff commonly used is the use of LCD status displays that do not have back lights. This results in a status display that is useless in low ambient light conditions.
The LCD's using ambient light to illuminate the display are sometimes difficult to view even with high levels of ambient light. Other LCDs are illuminated from the inside so that the visibility of the displayed information is improved. As a result, some electronic devices have LCDs with back lighting. Back lighting the LCDs generally provides a more uniform image and one which is visible regardless of the level of ambient light. However, conventional back lighting requires use of additional power resources to back light the display. Furthermore, conventional lighting methods, such as LEDs, fail to illuminate a broad area of the LCD uniformly.
One approach for illuminating a liquid crystal display device is described in U.S. Pat. No. 5,453,855 issued to Nakamura et al. on Sep. 26, 1995. The '855 patent teaches back lighting an LCD device using a reflective surface in conjunction with a plurality of LEDs. The LEDs, while requiring less power than an incandescent light bulb, nonetheless consume additional system power.
Other types of electronic devices also face design challenges and solutions with respect to back lighting. For instance, electronic watches have been provided with back lighting so that the face, in some cases a liquid crystal display or an analog dial, can be viewed in low levels of ambient light. One solution for back lighting a face of the watch is to include an electroluminescent lamp. However, one of the drawbacks of an electroluminescent lamp is that it requires high voltage alternating current to drive the lamp, thereby requiring additional power from the system.
Accordingly, what is needed is a way to illuminate a display device without consuming additional system power. What is further needed is a useful manner for dissipating excess heat from system components.
SUMMARY OF THE INVENTION
The present invention involves the use of thermoluminescent materials to provide lighting to secondary devices, such as liquid crystal status displays on a portable computer.
In one embodiment, a display apparatus has a back light powered by waste heat. The display apparatus includes an informational display device having a thermal illumination member disposed on a surface of the display device. The display apparatus also includes a heat producing component and a heat conveying unit thermally coupled between the thermal illumination member and the heat producing component. Waste heat from the heat producing component is conveyed to the thermal illumination member. The thermal illumination member provides illumination to the display device when heated in this manner. In another embodiment, the heat producing component and the thermal illumination member incorporates a heat distributing member for evenly distributing the heat.
Another object of the invention is to provide a portable computer having a backlit LCD status display. The portable computer has a computer body, a keyboard in a top surface of the body, and a display. Inside the computer body is a printed circuit board with a CPU having a heat slug, and a heat sink mounted on the heat slug. A status LCD is mounted in the top surface of the computer body, and has two top surfaces forming approximately a ninety-degree angle between them. Alternatively, the two surfaces could be disposed at about a forty-five degree angle, or disposed substantially flush with the computer body. The status LCD projects above the computer body, which facilitates a user's ability to view the status LCD from a normal typing position. Further included in the portable computer is LCD controller circuitry for determining display information for the status LCD and a communication unit for communicating between each status LCD and the LCD controller. The communication unit provides power to the status LCD. Behind a top surface of the status LCD is a thermally illuminated strip. A heat pipe conveys eat from the heat sink on the CPU to the thermally illuminated strip. The thermally illuminated strip provides back lighting to the LCD.
Yet another embodiment of the invention includes a method for backlighting a display apparatus. The method involves providing a display device and a system with a heat producing component, coating a surface of the display device with thermoluminescent material, and conveying waste heat from the heat producing unit to the thermoluminescent material. The waste heat causes the thermoluminescent material to illuminate the display apparatus.
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Cool Kenneth J.
Gateway Inc.
Nguyen Jimmy H.
Schwegman Lundberg Woessner & Kluth P.A.
Shalwala Bipin
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