| 摘要 |
PURPOSE:To obtain an accurate gradation output with less influence of noise even for an input close to black level (density is large) by constituting the titled sensor whether the sensor itself is a voltage variable type capacitor in construction or a voltage variable type capacitor is connected in parallel with the sensor, in the charge storage type image sensor. CONSTITUTION:As for the electrical equivalent circuit of an image sensor 3, a resistor R varies depending on the quantity of light while a capacitor C does not vary in a conventional sensor. Therefore, the relation between the quantity of incident light and that of an output goes to linear. Hence the current dis charged from the capacitor C running through the resistor R is reactive to the quantity of light linearly without depending on the voltage. In this invention, the capacitor C or a capacitor connected in parallel with this C is made of voltage sensitive type to improve the S/N of the sensor. By producing the image sensor so that the capacitor C goes to voltage sensitive type or by connecting such kind of element in parallel connection, it is provided that the voltage across the capacitor C drops because the discharge enhances in case the quantity of light is large (white density) hence the capacitance becomes larger. In case of black level, the effect is reverse.
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