| 摘要 |
PURPOSE: A system and a method for sensing forged fingerprint at a fingerprint input device are provided to sense a blood oxygen saturation of a finger, a heart rate and an absorption rate so that it can check that a man to be identified is alive and the fingerprint is forged. CONSTITUTION: The system comprises a scanner(100), an interface(200), and a signal processor(300). The scanner(100) includes a prism, a lens, an image sensor, an infrared ray emitter, a red light emitter, and a photo transistor. The image sensor converts an image, captured by the lens, into a digital image. The interface includes a filter(210), an amplifier(220), and an AD converter(230). The filter(210) eliminates a direct current component from a sensed signal transmitted by the photo transistor. The amplifier(220) eliminates noises from the filtered signal and then amplifies the filtered signal. The AD converter(230) converts the amplified analog signal into a corresponding digital signal. The signal processor(300) processes the signal transmitted by the interface(200), senses an absorption rate of the infrared ray and the red light, and according to the sensed absorption rate, checks whether the fingerprint is forged.
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