초록 ▼

To eliminate or suppress amplifier noise in amplifiers (6, 7) connected to a semiconductor light sensor, for example of a charge coupled type, in which the noise introduced by the amplifiers has a frequency spectrum which is low with respect to the clock frequency of operation of the sensor, the min

To eliminate or suppress amplifier noise in amplifiers (6, 7) connected to a semiconductor light sensor, for example of a charge coupled type, in which the noise introduced by the amplifiers has a frequency spectrum which is low with respect to the clock frequency of operation of the sensor, the minimum value signal from the light sensor, as amplified, is determined; the maximum value of the signal, as amplified, is determined; and a reference is derived based on the minimum value, for example by clamping the minimum value, or utilizing the minimum value as a dynamic reference for subtraction from the maximum value, to thereby eliminate the effect of low-frequency shift of signals due to low-frequency noise of the amplifiers; various circuits may be used, such as clamping circuits (FIG. 3), threshold or non-additive mixing circuits (FIGS. 4, 5) coupled to a subtraction stage (24), band-pass filtering and envelope demodulation (FIG. 6: 28, 29, 30) or synchronous demodulation (FIG. 7: 34, 35) using the scanning clock frequency (36, 37) for synchronous demodulation, coupled with frequency limiting the output to, for example, one-half clock frequency in a low-pass filter (39).

대표청구항 ▼

Method of suppression of additively superimposed noise in a semiconductor light sensor－amplifier combination having a semiconductor light sensor element (1); clock signal supplying means (4, 5) respectively energizing the light sensor in accordance with clock signals for transfer of read-out signals

Method of suppression of additively superimposed noise in a semiconductor light sensor－amplifier combination having a semiconductor light sensor element (1); clock signal supplying means (4, 5) respectively energizing the light sensor in accordance with clock signals for transfer of read-out signals therefrom; output means (2, 3) coupled to the sensor and receiving output signals therefrom varying between a maximum level, in dependence on the intensity of incident light, and a minimum level; and amplifier means (6, 7) amplifying the output from said output means, and providing an amplified output signal, said amplifier means introducing noise signals (UN), the noise from the output means being at a frequency which is low with respect to the frequency of the clock signal, comprising, in accordance with the invention, the steps of sensing the maximum value of the output signal from the amplifying means which includes the signal from the sensor and an additive component respresentative of the then instantaneous noise of the amplifying means (US+N), sensing the minimum value signal; detecting the sensed maximum value signal and the sensed minimum value signal; and subtracting the detected signals from each other to thereby eliminate low-frequency shifting effects due to said low-frequency noise.