Abstract: A floating diffusion (331) is created substantially at center of the light-receiving surface of an embedded photodiode (31), with a gate electrode of a transfer transistor (32) surrounding the floating diffusion. The concentration (or depth) of impurities in a p+-type semiconductor region, n-type semiconductor region or p-well region is changed in an inclined form so that a potential gradient being inclined downwards from the circumference to the center is created when an appropriate bias voltage is applied to the pn junction. The photocharges produced by incident light are rapidly moved along the potential gradient toward the center. Even in the case where the photocharge storage time is short, the photocharges can be efficiently collected since the maximum moving distance from the circumference of the photodiode (31) to the floating diffusion (331). Thus, the photocharges produced by the photodiode (31) are efficiently utilized, whereby the detection sensitivity is improved.

Abstract: A biodegradable or hydrolyzable toner for electrophotography, which permits the easy reclaiming and recycling of used copying paper, permits the easy deinking by an existing deinking system, can decrease environmental pollution caused by a toner waste, and has excellent toner properties owing to the uniform dispersion of additives, the toner containing, as a binder resin, a lactic acid-based resin of the formula (1),H--[--O--CH(CH.sub.3)--CO--].sub.n --OR (1)wherein R is an alkali metal or an alkaline earth metal, and n is an integer of 10 to 20,000.

Abstract: An analog to digital conversion method and apparatus includes the use of a scaling circuit 15 to scale the magnitude of an analog signal D applied to ADC 4 to within an acceptable input range. A calibration circuit 16 generates a signal M indicative of the effect of the scaling circuit 15 upon a digital signal E produced by the ADC 4. An adder 14 adds the calibration signal M and the digital signal E of ADC 4 to yield a digital output signal N which is the digital representation of measured analog input signal A.