Alarm Device Power Gating for Sensor and CPU Energy Reduction
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Solution Overview
Problem
Conventional fire alarm devices consume excessive power due to continuous measurement of light or temperature, leading to battery drain and increased maintenance costs, especially since they are often placed in hard-to-reach locations.
Innovation Solution
An alarm device with a power gate controller that selectively supplies power to the sensor and CPU only during measurement periods, using a power gate to reduce consumption, and employing volatile and nonvolatile memory to store and restore data efficiently, allowing for immediate processing upon power resumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous measurement of physical quantity is performed, then reliability of abnormal situation detection is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic measurement by the measurement unit, which measures the physical quantity at predetermined intervals rather than continuously. The control unit activates the measurement unit periodically, and the power supply unit provides power only during these measurement periods. This periodic operation maintains detection reliability by regularly monitoring the physical quantity while significantly reducing power consumption compared to continuous measurement.
2Use of energy by moving object
If power supply is stopped during interval between measurement periods, then power consumption is reduced, but data continuity may be affected
Solution Approach 1:
The control unit performs preliminary actions by determining in advance whether the measured physical quantity indicates an abnormal situation. When an abnormal situation is detected, the control unit activates the notification unit to alert the user. This preliminary determination ensures that critical information is captured and acted upon before power is cut during intervals, maintaining data continuity for important events while allowing power savings during normal operation.
Solution Approach 2:
The notification unit serves itself by being activated automatically when the control unit determines an abnormal situation exists. The system uses its own measured data to trigger notifications without external intervention, ensuring that information about abnormal situations is preserved and communicated even though power is periodically stopped.
3Ease of operation
If battery is used for power supply, then ease of installation is improved, but maintenance frequency increases due to battery drain
Solution Approach 1:
The power supply unit provides power to the measurement unit and control unit only during predetermined measurement periods, cutting power during intervals between measurements. This periodic power supply dramatically reduces overall battery consumption, extending battery life from what would be required for continuous operation to a much longer duration, thereby reducing maintenance frequency while maintaining the ease of battery installation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Significantly reduces power consumption and extends battery life, minimizing maintenance needs and costs by optimizing power usage and data handling in fire alarm devices.
Implementation Method 1
a power gate which selectively allows or stops power supply to the CPU and the sensor portion in accordance with control by the power gate controller
Implementation Method 2
a sensor portion which measures the physical quantity and transmits a measured value to the CPU
Implementation Method 3
a light-emitting element which emits light having high directivity
Implementation Method 4
light emitted from the light-emitting element can be scattered by smoke and enter the light-receiving element
Data Source
AI summary
In the microcomputer in the alarm device, supply of power to a sensor portion or a CPU in a sensor is allowed or stopped by a power gate controlled by a power gate controller. In addition, a volatile memory portion and a nonvolatile memory portion are provided in the CPU, data of the volatile memory portion is stored in the nonvolatile memory portion before supply of power to the CPU is stopped, and the data of the nonvolatile memory portion is restored to the volatile memory portion after the supply of power to the CPU is resumed. Thus, during an interval between measurement periods, supply of power to the sensor portion and the CPU can be stopped, so that low power consumption can be achieved compared with the case where power is continuously supplied.