Abstract: A digitally-controlled pyroelectric signal sampling circuit is proposed, which is designed to process the alternating current (AC) signal from a pyroelectric device, such as a pyroelectric infrared sensor, such that the AC signal is converted into direct current (DC) signal. The proposed digitally-controlled pyroelectric signal sampling circuit is characterized by the use of a microprocessor in conjunction with a crystal oscillator whose operating characteristics would be substantially unaffected by temperature changes in the ambient environment. This feature allows the generated trigger signal and sampling signals to be substantially fixed in frequencies and timings, without drifting due to temperature changes in the ambient environment, and therefore allows the digitally-controlled pyroelectric signal sampling circuit of the invention to provide a more accurate DC output than prior art.

Abstract: A gas concentration measuring device and a gas concentration measuring method are provided. The gas concentration measuring device includes an IR gas measuring module, a circuit processing module, and a display module. In the gas concentration measuring method, the IR gas measuring module measures concentration of a gas and outputs a concentration signal corresponding to the measured gas concentration. The circuit processing module receives the concentration signal and processes the concentration signal to obtain an electrical signal in linear proportion to the gas concentration. The display module receives the electrical signal and displays the gas concentration corresponding to the electrical signal.

Abstract: A digitally-controlled pyroelectric signal sampling circuit is proposed, which is designed to process the alternating current (AC) signal from a pyroelectric device, such as a pyroelectric infrared sensor, such that the AC signal is converted into direct current (DC) signal. The proposed digitally-controlled pyroelectric signal sampling circuit is characterized by the use of a microprocessor in conjunction with a crystal oscillator whose operating characteristics would be substantially unaffected by temperature changes in the ambient environment. This feature allows the generated trigger signal and sampling signals to be substantially fixed in frequencies and timings, without drifting due to temperature changes in the ambient environment, and therefore allows the digitally-controlled pyroelectric signal sampling circuit of the invention to provide a more accurate DC output than prior art.

Abstract: An air-quality conditioning device is proposed, which can be singly used or used in combination with a small air conditioner. In an enclosed space, concentration of carbon dioxide is detected by a carbon dioxide concentration detecting module of the device. While the detected concentration of carbon dioxide reaches a predetermined upper limit value, an air conditioning mechanism is driven by an air-conditioning controlling module for introducing external fresh air to the space. While the carbon dioxide concentration reduces to a predetermined lower limit value, the air conditioning mechanism is driven for stopping the introduction of the external air. Therefore, the carbon dioxide concentration can be properly adjusted in the space so as to maintain good air quality therein.