Light receiving detection circuit having a high-pass filter and an amplifying circuit

• Main Author: DAIO MITSUAKI
• Format: Patent
• Language: English
• Published: 14.05.2013
• Subjects: BASIC ELECTRIC ELEMENTS; BASIC ELECTRONIC CIRCUITRY; CALCULATING; COMPUTING; COUNTING; COUNTING MECHANISMS; COUNTING OF OBJECTS NOT OTHERWISE PROVIDED FOR; DETECTING MASSES OR OBJECTS; ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS; ELECTRICITY; GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; MEASURING; PHYSICS; PULSE TECHNIQUE; TESTING

A light receiving detection circuit has a light receiving element configured to receive light emitted from a corresponding projection element, a current/voltage conversion circuit that converts a current signal passing through the light receiving element into a voltage signal, and a filter portion that has a plurality of stages. The filter portion has a high-pass filter and an amplifying circuit. The high-pass filter is able to be switched such that a time constant of the high-pass filter increases when the light receiving element receives light emitted by the corresponding projection element such that the time constant decreases when other projection elements except for the corresponding projection element emit the light.