In pursuit of developing a next-generation pick-up device having high definition and ultrahigh sensitivity features, research continues on a new type of image sensor that combines a HARP target and a field emitter array. A new field emitter array on a small-sized substrate is designed and a unique packaging technique is proposed. The prototype device is sealed in a vacuum package with a thickness of only about 10 mm and has 128 horizontal and 96 vertical pixels. Experimental results show that images could be successfully reproduced for the first time ever in a device of this type. Highly sensitive characteristics and propr resolution were also obtained with the device. The prototype image sensor can operate stably for more than 250 hours, demonstrating its feasibility and potential as a next- generation image pickup device.
A new type of image sensor featuring a unique structure is studied with the aim of achieving both super-high sensitivity and ultrahigh-definition. This image sensor combines a field emitter array (FEA) and a high-gain avalanche rushing amorphous photoconductor target. We investigated the conditions for improving resolution in a vacuum chamber by inserting a mesh electrode between the FEA and the target. The results indicate that the resolution can be improved by strengthening the accelerating electric field between the FEA gate and the mesh, and by placing the mesh closer to the FEA. We also propose a new parallel readout system that is suitable for an ultrahigh-definition image sensor. Dividing the target into multiple segments and reading out signals for each segment simultaneously enables us to decrease the drive frequency. In our first attempt, we synthesized a good 60 X 60 pixel image from two 30 X 60 pixel segments.
To develop a high-definition image sensor having ultra-high sensitivity far superior to CCDs. A new compact image sensor consisting of a matrix field emitter array (FEA) and a high- gain avalanche rushing amorphous photoconductor (HARP) target is studied. Most research on devices with FEAs has so far focused on flat displays and high-frequency devices. Although the concept of a flat image sensor with FEAs has been proposed before, image sensors with FEAs have yet to be fabricated. In this paper, the fundamental driving characteristics of a new flat image sensor comprised of an X-Y matrix FEA set face to face with a HARP target have been investigated in a vacuum chamber for the first time. Experiments confirmed that the device successfully picks up images. High-sensitivity is achieved with the HARP target, and the temporal fluctuation and spatial variation of the emission currents obtained from the FEA have almost no effect on the signal output currents. Furthermore, the resolution characteristics are affected by the mesh voltage and by divergence of the emission from the field emitter tips.
We have developed a compact HDTV camera tube that combines high sensitivity with high resolution and is compact enough for hand-held cameras. This new camera tube employs an 8-micrometers -thick HARP (High-gain Avalanche Rushing amorphous Photoconductor) target. Unlike other photoconductors, this target is unique in that its sensitivity can be increased to very high levels to cope with darker illumination. In addition, we have achieved high resolution over the entire picture through the use of a new all-electrostatic focusing and deflection system in the 18-mm-diameter tube that facilitates the use of a narrow electron beam while assuring the optimal suppression of aberration. a prototype hand-held HDTV camera equipped with three of these camera tubes has attained a maximum sensitivity of 2,000 lux at f/25 (normal gain) and a limiting resolution of more than 1,400 TV lines.
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