[in Japanese]

View full abstract

An on-chip inner-layer lens has been developed to improve the photo-sensitivity and smear of CCD image sensors. The inner-layer lens structure consists of a boron-phospho-silicate-glass (BPSG) layer and a heat melting transparent resin. The refractive indices for the inner-layer lens was higher than the BPSG layer and the planarization layer. Taking the incident angle into account, we have applied a new three dimentional simulation to the inner-layer lens to investigate the optical pass. We fabricate a 1/4-type IT-CCD image sensor with an inner-layer lens. This fabricated results of an image sensor has been explained well by the new three dimentional optical simulation. The increase of photo-sensitivity using the inner-layer lens technology is 16% without deterioration in the CCD characteristics. Furthermore using the inner-layer lens reduces the smear value by 70%.

View full abstract

A single-layer metal-electrode CCD image sensor was studied with the purpose of simplifying the steps in the production process with the aim of achieving low-cost sensors and supplressing smear noise. The inter-electrode gap of the single-layer electrode was decreased to 0.3 micrometer to achieve charge-transfer efficiency of unity. Boron ion-implantation which is self-aligned to the interelectrode gap was introduced to suppress degradation in charge-transfer efficiency. A reduction in the number of process steps needed to fabricate a 1/3-inch-format 360K-pixel interline transfer CCD image sensor was achieved. Vertical resolution was 350 TV lines. Low smear noise of-108dB was obtained.

View full abstract

Multiple multielectrode-potential-wells in the vertical CCD (VCCD) are formed by a shiftresistor and transfer charges at a high speed in horizontal blanking time. Signals are amplified, sample -holed at each VCCD output, and read out by a shiftresistor. The single-layer CCD/CMOS process and the VCCD driving circuitry, which generates transfer and readout pulse, realize these concepts. The 1/2-inch 2 M-pixel progressive scan image sensor is designed using 0.8-μm technology and its fundamental characteristics are evaluated. The sensor has a saturation signal charge of 3.4 × 10⁴ electrons, a smear level of 92 dB, a sensitivity of 5.4 × 10² electrons/lx with a 40% fill factor, no picture degradation caused by pulsing a power dissipation of 89 mW, a random noise of 18 electrons, fixed pattern noises of 17 electrons in the dark and 2.5% in the light, and a chip size of 10.3 (H) × 6.0 (V) mm².

View full abstract

This paper introduces examples of CMD high-resolution cameras and analyzes the factors that limit the performance of CMD and other imagers. The necessary conditions for achieving higher resolution are explained. Making the quantum efficiency near unity is the one and only method to improve the optical performance. In electronics, the main subjects are noise suppression and power saving. It is concluded that CMDs and some APSs (Active Pixel Sansors) are superior to the CCD family from the viewpoint of wide bandwidth and low power consumption.

View full abstract

In this paper, we propose a novel image sensor by which the image signal can be compressed. Since the image signal is compressed on the imager plane by making use of the parallel nature of image signals, the amount of signal readout from the imager can be significantly reduced. Thus, the proposed sensor can potentially be applied to high-pixel-rate cameras and real-time processing systems which require very high-speed imaging and very high resolution for real-time imaging; the very high bandwidth is the fundamental limitation to the feasibility of such high-pixel-rate sensors and processing systems. The proposed sensor utilizes a conditional replenishment algorithm; it detects temporally changing pixels as active pixels and output them. An analog circuit for processing in each pixel and an entire sensor architecture have been designed. A first prototype of a VLSI sensor chip has been fabricated. Results of experiments using the prototype chip are shown.

View full abstract

We have newly developed a 3-CCD camera system to improve performance under difficult conditions such as back-lighting, Electronic Image Stabilization mode, electronic zoom, and insufficient illumination. One of the key technologies of the system is new signal processing methods such as Neuro-Gamma, Vertical Stagger Processing, and New Noise Reduction in order to improve the performance under the above conditions. The 0.5 μm process and chip integration produce digital LSIs with high density integration and low power.

View full abstract

A new 4 CCD Hi-Vision portable color camera utilizes consumer-type CCDs, leading to compact size, light weight, low cost, and low power consumption. As a result, the horizontal and vertical resolutions are more than 650 TV lines thanks to the new 4 CCD dual green system and special pixel offset imaging between G 1 and G 2 CCDs and between G 1/G 2 and R/B CCDs. A digital processing circuits allows switching between Hi-Vision and NTSC modes.

View full abstract

The digital processing cameras are now being developed actively, because in recent years CMOS gate arrays of sufficient speed and scale have been achieved. Because a digital image processor has ideal signal delay and no crosstalk, digital processing camera has clear image quality, however, the smoothness of the image is inferior to that of an analog processing camera. It is found that if moire is produced by the contour compensator the image smoothness is inferior and the moire is mainly generated by nonlinear process. To reduce aliasing components of nonlinear process harmonics, a double-sampling-rate contour-compensator is developed. This compensator erases the greater part of conventional compensator moire and increases image smoothness. This paper describes contour-compensator moire-generating mechanism and moire-reducing contour-compensation method.

View full abstract

We have developed a new signal processing method for expanding the dynamic range of a video camera. A variable and nonlinear gamma characteristic is applied to the input image depending on the distribution of the luminance. We set the gamma characteristic for the back-lit images so as to amplify the luminance of the dark pixels and preserve the contrast of the bright pixels. We have established the decision rule of the gamma characteristic using the learning algorithms of neural networks in order to make the decision rule correspond human vision. The implementation of the gamma decision rule consists of a cascade connection of RAMs, which decreases the required total capacity of RAMs by 1/100 compared with the implementation with a single RAM. The effect of our new method is expand the dynamic range by three times.

View full abstract

We have developed a 2K × 2K progressive scan color camera system. In the development, two key technologies were applied. One of the technologies enables a sensor to be operated at a high data rate. In the system, four CMD (Charge Modulation Device) chips with 1920 (H) x 1035 (V) pixel are driven at 167-M pixel/sec in progressive scan mode respectively. The other technology uses the four-sensors pickup method in which two sensors are used for green and two sensors for red and blue. The spatial offset imaging method in the vertical direction was applied to the two green sensors, thus increasing the number of vertical lines in the green channel to 2070 (twice the number of one CMD). Using these technologies, an ultra high definition camera with a data rate of 334-MHz pixel/sec has been achieved and we are sure that a vertical limiting resolution has been produced of more than 1500 TVL on a color monitor.

View full abstract

An infrared-bi-color image sensor was developed with a barrier-height-controlled Schottky-barrier photo diode array for precise temperature images. Low and high barrier-height diode pixels are arranged vertically next to one another using a selective area ion-implantation technique. The infrared-bi-color image sensor can obtain the temperature image precisely and without the emissivity assumption.

View full abstract