A low noise driving method for CCD imaging devices is developed. In the method, a reset pulse is controlled according to the signal level of the CCD. By an evaluation employing a CCD of VGA size, it has become apparent that signal charge acquired from more than 100 pixels can be read continuously without reset pulses at a scene of 1/64 luminance and that low frequency noise which is conspicuous in a reproduced picture can be reduced remarkably.
Threshold voltage variation and random noise generated in pixel source follower transistors of a CMOS image sensor have been measured by using an array test circuits consisting of the transistors whose electric contacts of the gate poly-silicon are on the isolation region and on the active region. Moreover, operating condition dependency of the random noise generated by pixel transistors have been measured with a LOFIC CMOS image sensor in which the noise of the readout circuits have reduced to about 0.5e^- (input referred). In this paper, these results are discussed.
We propose a new CMOS image sensor with a thin overlaid panchromatic organic photoconductive layer as the best candidate for sensors with reduced pixel size. We experimentally made the trial product of the CMOS image sensor in order to verify the potential capability of our proposal, and to prove the validity of the organic CMOS sensor.
This paper describes a new type of global electronic shutter pixel for CMOS image sensors. A global electronic shutter is necessary for imaging fast-moving objects without motion blur or distortion. The proposed pixel has two potential wells with pinned diode structure for two-stage charge transfer that enables a global electronic shuttering and reset noise canceling. A prototype high-speed image sensor fabricated in 0.18μm standard CMOS image sensor process consists of the proposed pixel array, 12-bit column-parallel cyclic ADC arrays and 192-channel digital outputs. The sensor achieves a good linearity at low-light intensity, demonstrating the perfect charge transfer between two pinned diodes. The input referred noise at the pixel level is measured to be 6.3e^-, which is three to four times smaller than that of conventional CMOS image sensors with global electronic shutter pixels.
A polarization-analyzing CMOS sensor with an image sensor architecture was proposed and demonstrated. The sensor has a feature of monolithically embedded polarizer. We designed a prototype sensor equipped with a polarization-analyzing pixel array based on the concept. Embedded polarizers with different angle were implemented to realize a real-time absolute measurement of incident polarization angle. We characterized the functionality and performance of the designed polarization-analyzing CMOS image sensor.
We have developed retinal stimulator embedded with light-sensing function in distributed microchip architecture for subretinal implantation. The fabricated device was implanted in a rabbit eye ball and successfully worked.