Field of Invention
The invention relates to an object detection method for power management and, in particular, to an object detecting method using ultrasonic waves and an object detection apparatus.
Related Art
Along with the development and maturity of electronic technology, various electronic appliances, such as televisions, air conditioners and microwave ovens, have become closely tied to human lives. Generally, it is user's habit to keep those electronic appliances in a standby condition or to leave their plugs remain plugged even when those appliances are not in use. Such habit results in unnecessary power consumptions. Even the power consumptions of electronic appliances when not in use are not much, for example, a standby television consumes about 6 to 15 watts, a standby microwave oven consumes about 0.1 to 4.2 watts, and a standby stereo consumes about 0.04 to 14.9 watts, the accumulated power consumptions of those appliances are still considerable. It is estimated that each household may thus consume additional 300 kWh per year. Not only the power is wasted, but also the electricity cost is increased. This contradicts to the current trend of energy saving.
Along with the development of smart home appliances, user detection technology has been adopted when designing home appliances to let the home appliances enter into a power saving mode when not in use. Current user detection technology uses an infrared ray sensor or an image processing and detecting technique. The infrared ray sensor senses the move of a user by sensing the temperature variations within a sensed range (the variation of the infrared ray) when the user enters or leaves the sensed range. The image processing and detecting technique performs a determination based on the images taken within a continuous time period. When the user moves within an image-taking range, the images taken would be different along with the move of the user. The user's move can be analyzed by comparing the multiple images taken during the continuous time period.
However, although the infrared ray sensor can be used to determine the move of the user, the distance between the user and the infrared ray sensor within the sensed range cannot be determined based on the variation of the infrared ray.
The image processing and detecting technique requires the process of huge amount of image data input and algorithm analyses to determine the move of the user, which results in higher costs to build hardware and software. The image processing and detecting technique of a higher level can even analyze the distance to the user, but it requires hardware and software of a higher level.