Image pickup tubes

G.A. Swartz, Closed-Form Solution of I-V Characteristic for a-Si H Solar Cells Isamu Shimizu, Electrophotography Sachio Ishioka, Image Pickup Tubes... 

The first attempt to realize such imaging device uses was made by Imamura et al. (1979), and a vidicon-type image pickup tube was proposed. Especially in the field of color television cameras, there have been great expectations that this device will lead to the realization of high-performance imagers. 

This section focuses on a-Si H image pickup tubes and presents a-Si H property requirements and fabrication and impurity doping techniques, as well as the structure of photoconductive targets. Pickup tube characteristics that have been attained and some of their applications will be described. 

In ordinary image pickup tube operation, the transparent electrode is biased positively with respect to the cathode. When the low-velocity scanning beam lands on the surface of the photoconductive target, the surface is charged negatively and brought to cathode potential. 

Fig. 1. (a) The fundamental structure and operation mechanism of the image pickup tube, (b) The equivalent circuit of the image pickup tube. 

Typical deposition parameters for image pickup tube a-Si H are listed in Table I. 

These results suggest that a-Si H of dihydride configuration provides the better characteristics as a photoconductor for the image pickup tube. The result that the dihydride configuration a-Si H has a large °p is consistent with previous theoretical calculations (Allan and Joannopoulos, 1980). It is interesting that this situation seems to be quite different from results reported for an a-Si H solar cell, where a monohydride configuration is believed to be favorable. 

Image pickup tubes are operated at an applied voltage high enough to draw out the saturated level of the photocurrent as shown in Fig. 7. In this region, the photocurrent is determined by the number of electron-hole... 

Fig. 10. Resolution pattern reproduced by the a-Si H image pickup tube.

These properties indicate that a-Si H image pickup tubes are quite useful over a wide area of applications. The TV camera for an x-ray image intensifier system is an example of such an application (Iamura et al., 1982 Ishikawa et al., 1982). 

Although a-Si H has been proved to be a very good photoconductor for image pickup tubes, some problems remain to be solved. As has already been mentioned, the decay lag in a-Si H tubes is presently 4%, and it is necessary to reduce this lag, especially in order to apply the technology to broadcasting use. The decay lag as determined by the capacitance of the... 

The last volume of this miniseries, 21, Part D, covers device applications, including solar cells, electrophotography, image pickup tubes, field effect transistors (FETs) and FET-addressed liquid crystal display panels, solid state image sensors, charge-coupled devices, optical recording, visible light... 

---