現像時間の経過に伴うハーフトン画像の拡大は著しい。 単線ハーフトン画像の拡大特性について, 特性曲線との関連において検討する。 特性曲線の低露光量域への移行速度とハーフトン画像のコンタクトスクリン濃度分布上の拡大速度との相関を求める。 更に, リス現像の現像進行帯について考察する。

抄録全体を表示

Calcium carbonate or Talc powder which was used as the model of spraying powder on a sheet-fed machine was forced to generate the frictional electricity by rubbing against a surface of aluminium plate, and then the decay curves of the powder were observed under the various conditions of relative humidity by use of the apparatus mentioned before. In spite of great difference of the relative humidity when the measurements were carried out, the gradient of the logV-t (where V is the electric potential measured, t is the time elapsed.) which were plotted as the base of the decay curves of electric discharge on the powders showed to be almost same.
Next the logV-t on the surface-treated powders with MgCl₂ (10^-1-10^-2mol/l) or CuCl₂ (10^-1mol/l), and of annealed substances of the powder described above were estimated. While the gradient of logV-t of the powder treated with MgCl₂ (10^-1mol/l) showed to be greater than that of the other treatments, the annealed substances became all to be lower gradient.
Further more the frictional electricity of the mixture of Calcium carbonate and Talc powder was measured, but it was scarcely detected.

抄録全体を表示

In considering the print quality of small image areas, such as postage stamps, it is important to note that how the detail of images are reproduced, is one of the vital factors that largely affect image quality. In photogravure printing, in particular, detail reproduction is considered to greatly influence the visual impression, owing to the inherent lateral spreading property of gravure ink on the paper.
In this study therefore, an objective evaluation of detail reproduction was attempted from the standpoint of a decreasing tendency in micro-density obtained by trial test charts so as to investigate the effect of the physical nature of the ink and the paper on reproduction, and the correlation between reprodution and subjective evaluation.
The results may be summarized as follows:
(1) On the square wave chart print, the decreasing tendency of micro-density becomes great and gradually approaches the limit of resolution with an increase in the square wave number. Finer images than screen rulings were sometimes reproduced. The effect of ink viscosity on reproduction was remarkable as the square wave numbers became larger.
(2) The decrease in micro-density obtained from highlights on combination charts also became great as the square wave numbers increased (the same as with square wave charts), but the change is far more remarkable than that in the former.
(3) The effects of unevenness, such as “bridge” and “speckle, ” additionally generated in the printing operation were great. The effect of “bridge” from the middle tones to the shadows was especially pronounced.
(4) The dot spreading tendency of printed matter had a close relationship to the decreasing tendency of micro-density. The larger the dot spreading, the greater the decreasing tendency. Also, with any type of paper the decrease in ink viscosity caused the dot spreading tendency, strengthening the decreasing tendency of micro-density. This phenomenon was observed with un-coated types of paper more than with coated types.
(5) For tone reproduction determined from a gray scale, coated paper was apt to be more affected by the increase or decrease in ink viscosity than un-coated paper in contrast with the results on detail reproduction.
(6) For subjective evaluation of detail reproduction of pictures of women, individual differences were observed between judges, and differences between the samples were not clearly classified, whereas for evaluation of overall image quality, it was found that there were few individual differences, and differences between the samples were finely classified.
(7) No simple correlation was found between the results of subjective evaluation of detail reproduction and the decreasing tendency of micro-density with the square wave number. However, results on detail clarity could be objectively evaluated from the decreasing tendency of micro-density obtained by which the pictures were printed on the same type of paper with only the ink viscosity changed. On the other hand, it was difficult to establish definite relationships between the results of subjective evaluation of detail reproduction and the decreasing tendency of micro-density with printed matter with varied ink viscosity and paper, because of other complicated evaluation factors such as tone reproduction and unevenness.

抄録全体を表示