Multi-tap CMOS pixels that are composed of a single photodiode, multiple sets of a charge transfer gate and storage diode, and a draining gate can implement functional imaging. In this paper, imaging systems based on the multi-tap CMOS pixel are categorized into those with synchronized active illuminations and those using coded exposure. Applications for quantitative wide-field imaging based on spatial frequency domain imaging (SFDI) using structured light projection and multi-exposure laser speckle contrast blood flow imaging (MELSCI) utilizing multiple exposure times are shown. The multi-tap CMOS pixel provides additional benefits like suppression of ambient light and motion artifact with SFDI and efficient sampling at a video rate with MELSCI.
This paper presents a CMOS proximity capacitance image sensor technology achieving 0.1aF detection accuracy with high spatial resolution with real-time imaging capability for industrial, life science, and biometric applications. The proposed image sensor circuits, its working principle and device structures are described in this paper, and additionally, we discuss the foreseen technology roadmap. The fabricated chips with 16.m pitch pixels achieved a 0.1aF detection accuracy with the input voltage of 20V, thanks to the employed noise reduction technology. The examples of capacitance imaging using the fabricated CMOS proximity capacitance image sensor are demonstrated.
We propose an adaptive exposure-time-control method for image sensors, which can control the exposure time for each pixel to reconstruct a high-dynamic-range image, while suppressing blown-out highlights and blocked-up shadows, according to the luminance and contrast of the scene. First, the proposed method determines the exposure time that maximizes the entropy of the entire image, as an image with high entropy contains more object details. In order to estimate the exposure time appropriate for the light and dark areas in the scene, the proposed method divides the image into blocks and estimates the exposure time that maximizes the entropy for each block. Because the proposed method captures and estimates several exposure times simultaneously, the time required for adjusting the exposure time is reduced. Simulation experiments show the effectiveness of the proposed method.
We propose an autostereoscopic display allowing two observers with adaptive fractional time-division multiplexing parallax barrier. Fractional time-division suppresses perceived flickers when the order of slit position is properly set. To make sure that both of the observers are located in the proper viewing zones to enable stereoscopy simultaneously, the number of time-division multiplexing is switched in accordance with the distance between them. The viewing zone without crosstalk for the second viewer is evaluated theoretically.