A logarithmic-converting CCD line sensor incorporating logarithmic-converting circuits which utilizes MOSFET's subthreshold operation was developed. The sensor has 2240×3 pixels that are 12μm×12μm. It outputs a signal logarithmically proportional to the integrated amount of the incident light over more than five orders of magnitude in intensity, and therefore it can take bright and dark objects at the same time. Furthermore, its output signal is proportional to the densities on the prints or the films. Therefore, the digital data converted from its output signal retains image quality, and the shading can be corrected by just adding or subtracting. We expect that this technology will be very useful for digital copiers, camera type scanners, and film scanners.

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We developed a 1/5-inch frame transfer CCD color image sensor with 270, 000 pixels. The sensor is a key device of input systems for multimedia equipments such as personal computers, workstations, and write out PDAs. The total number of pixels is 532 (H) × 500 (V), and unit cell size is 5.8 (H) × 4.5 (V) μm². A high sensitivity of 45 mV/1x was achieved in photo-electric conversion efficiency by optimizing the thickness of the membranes, and utilizing thinner polysilicon electrodes and multiple interference. A complementary stripe filter of Ye-G-Cy was used as a color filter. Manufacturing cost has been reduced by using a 20-pin transparent resin mold for packaging.

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A 1/4-inch format 560 k pixel IT-CCD image sensor was developed with a high-resolution electronic image stabilizing system that uses a driving method and novel process technology. The new pixel design, process, and on-chip color filter technology keeps almost the same characteristics as the conventional 1/3-inch format 360 k pixel IT-CCD image sensor, in spite of the new sensor's reduced pixel-size.

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A 1/4-inch format 250k pixel amplified MOS image sensor has been developed with the CMOS process. We developed a new circuit technique that uses a 0.8μm design rule to reduce pixel size while attaining vertical two line mixing and high sensitivity. Considering high speed operation and stacking photoconversion layers, we have designed scanner circuits and determined photodiode potential. As a result, a dynamic range of 75 dB and a sensitivity of 1.8μA/lx have been attained for a pixel size of 7.2 (H) × 5.6 (V) μm². Fixed pattern noise is-55dB for saturation current, additional smear is under 2.5 × 10^-6, and lag is under 1% on first field. We also confirmed high-speed operation up to a HDTV data rate.

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This paper describes a new method of FPN suppression that does not use memories on CMD imagers. This method does not require any changes in the conventional device structure. As part of this suppression method, we have employed a new drive method, which we also developed. In this drive method, the pixels are reset sequentially one by one. FPN can be reduced by removing dark signal, which is read out just after resetting, from output signal. We have shown that this method causes no deterioration in terms of photoelectric conversion and image lag, as compared with the conventional method. By this method, We achieved a FPN suppression ratio of 15.8 dB and suppressed FPN to-40.2 dBp-p in comparison with the saturation signal.

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We report methods of improving the color reproduction characteristics of industrial television (ITV) color cameras. Since ITV color cameras are used in a much wider range of situations and lighting conditions than home-use camcorders, it is difficult for them to automatically adapt their color reproduction characteristics according to the color rendering properties of the sources. Thus they have poor color reproduction with low-color light sources. We have extended the light range of color temperature variation of TTL auto-white-balance and achieved automatic color correction according to the kind of light source detected by using the ratio of RGB signals. These methods solve the problem and give good color reproduction regardless of the type of light source.

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A new image acquistion system is proposed to meet the increasing demand for a compact HDTV camera with high performance. The main idea of this system is to solve the contradiction between the shrinkage of the optical format size and the camera performance by equipping the camera with four-chip CCDs. In the newly developed color-separating system of the prototype camera, two of the four CCDs are assigned for the green light component and one each for the red and the blue component. We succeeded in improving the resolution by introducing spatial pixel offset imaging, in which the two G-CCDs are aligned by one-half pitch of a pixel and one of them is aligned with the R-CCD and the other with the B-CCD. This new method has two major advantages : it prevents the resolution degradation caused by the chromatic aberration of the lens and improves the resolution of chromatic signals over a wide range.

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A 811 × 508 pixel PtSi Schottky-barrier infrared CCD image sensor which has the greatest number of pixels for a Standard TV format was developed. We achieved a 38% fill-factor of 18 × 21μm size pixel for this image sensor by using 1.0μm design rules. The noise equivalent temperature difference with f/1.2 was 0.06 K at 300 K. The responsivity nonuniformity with a 300 K background signal was estimated at 0.45%. The sensor obtained execellent thermal imaging without uniformity correction.

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[in Japanese]

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[in Japanese]

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