| 摘要 |
A contact image sensor (CIS) chip uses a line transfer and pixel readout structure. Integration and signal readout are separated. The device provides more accurate data while avoiding distortion, vertical resolution reduction, and reduction of scan speed. Operational amplifiers combine signals from active photoelements and dummy elements to remove any dark fixed pattern noise or DC offset voltage from the output signal. The dummy elements are identical to the active photoelements except that they are shielded so that they receive no light. The linearity of the photoresponse is greatly assisted by this optical black level reference, strongly promoting accurate color reconstruction. One preferred embodiment entails the use as photoelements of photodiode Passive Pixel Sensors, while a second preferred embodiment uses phototransistor Active Pixel Sensors. A small holding capacitor capacitance increases the devices's sensitivity, reduces reset noise, and further improves signal-to-noise ratio. The chips may be butted together end-to-end on a single substrate in one line with approximately equal space between adjacent detectors. Thus, CIS module offering higher sensitivity, low reset noise, and high signal-to-noise ratio may be built using this device. All necessary clock pulses and operational amplifiers can be built on a single chip, reducing the necessary peripheral circuitry. Because the dummy element array operates independently from the active photoelement array, design flexibility for different CIS module configurations is promoted.
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