Electricity: motive power systems – Automatic and/or with time-delay means – Responsive to thermal conditions
Reexamination Certificate
1999-10-01
2001-02-20
Ro, Bentsu (Department: 2837)
Electricity: motive power systems
Automatic and/or with time-delay means
Responsive to thermal conditions
C318S452000, C318S484000, C388S921000, C388S934000
Reexamination Certificate
active
06191546
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to temperature control in electronic devices, and more particularly to method and apparatus for controlling a variety of cooling devices to regulate the temperature of heat producing components.
BACKGROUND OF THE INVENTION
Conventional electronic devices typically had to address only a single heat source such as a microprocessor or processor module. While microprocessors or processor modules continue to increase in power consumption, the associated support circuitry is also increasing in power consumption. This increase is due to the need to keep up with the higher operating speeds and performance of the microprocessors. Additionally, support devices such as batteries are required to discharge and charge in limited temperature ranges in order to meet regulatory safety requirements. Ignoring the additional heating from these other sources can lead to catastrophic failures. Thus a need exists to simultaneously monitor multiple heat producing components.
Traditional temperature control devices monitored the temperature on a large thermal mass such as a heat sink attached to an integrated circuit (IC), such as a microprocessor or module, or even just the ambient air within a cavity of an electronic device. Due to the low thermal drop across the IC-heat sink interface, the heat sink monitoring was a sufficient indication of actual IC die temperature. With the advent of higher power devices such as Pentium III processors and 3D enabled graphic controllers, which operate at different power levels depending on the actual use, the drop across the IC-heat sink interface varies. A further concern is that due to higher levels of integration, more power is being expended in a smaller die or module area. Additionally, due to the need to support different optional configurations for a postponement manufacturing process, the thermal IC-heat sink interface may not be predictable. To ensure that the IC does not exceed its thermal design specifications, manufacturers of the ICs have begun to incorporate thermal diodes onto the IC die which allow external circuitry to monitor the forward voltage drop of the diode, thus providing an indication of die temperature. However, when the temperature is monitored on the die, there is little feedback on how the heat being dissipated from the heat sink or other heat dissipation structure is affecting other devices within the electronic device or the external surfaces of the electronic device. Therefore, a need exists to more accurately monitor individual die or module temperatures while also providing system wide thermal control.
Several different temperature sensors have been developed to measure the temperature of electronic devices and thermal surfaces. Traditionally, thermistors with either positive or negative thermal coefficients were used typically with bridge circuits to provide a difference signal that gave an indication of relative temperature change. As previously stated, the need to monitor die temperature directly has required that IC manufacturers develop diode temperature sensors which allow for easy fabrication using conventional IC processes. Since the forward voltage drop of the diode is non-linear with temperature, the diode temperature sensor is typically accompanied by a companion IC which provides an analog-to-digital conversion of the diode voltage drop and the accompanying non-linear to linear conversion. Thus, the output of the diode temperature sensor is a digital output and cannot be directly incorporated into conventional analog controller circuits. Therefore, a need exists to have a temperature control circuit which can support multiple types of temperature sensors.
SUMMARY
An electronic device has a heat producing component thermally coupled to a heat dissipation structure. The electronic device further has control circuitry connected to a temperature sensor that senses the component temperature of the heat producing component. The control circuit is further connected to a cooling device also thermally coupled to the heat dissipation structure. The control circuit varies the cooling rate in a manner that cancels out a lag time which occurs during a change from a steady state condition of the component temperature. The cooling rate of the cooling device is varied by the control circuit in proportion to variation in sensed component temperature from the temperature sensor.
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Bausch James F.
Stryker Chadwick W
Van Brocklin Andrew L
Hewlett--Packard Company
Myers Timothy F.
Ro Bentsu
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