Pulse modulation light detection device, method, and electronic apparatus

Abstract

The invention provides a pulse modulation type light detection device. The pulse modulation type photodetection device has: a light emitting element emitting pulsed light synchronized with a pulse signal; a light receiving element receiving reflected light or transmitted light of an object to be detected by means of the pulsed light; a light-receiving signal of the light-receiving element to detect the presence or absence of an object; and a synchronous timing circuit to generate a pulse signal for causing pulsed light to be emitted multiple times in one cycle. The signal processing circuit detects the plurality of pulses, and outputs a detection signal indicating whether or not the object exists.

Description

technical field [0001] The present invention relates to a pulse-modulated photodetection device and a pulse-modulated photodetection method for emitting pulse-modulated light from a light-emitting element and detecting the presence or absence of an object, and more particularly to a FA (factory automation) and A pulse-modulated light detection device and a pulse-modulated light detection method suitable for OA (office automation) equipment and electronic equipment such as entertainment equipment for detecting coins and marbles. Background technique [0002] In FA and OA equipment such as copiers and printers, and electronic equipment such as entertainment equipment such as game machines, it is sometimes necessary to detect the passage of objects (such as recording paper, coins, marbles, etc.) in a predetermined path. A photodetection device that detects an object with light is relatively suitable for the above-mentioned detection because it does not touch the object. [000...

AI Technical Summary

Problems solved by technology

If the light from the inverter fluorescent lamp coincides with the emission timing, it will be erroneously detected as synchronous light, and if the light from the inverter fluorescent lamp does not coincide with the emission timing, or if the received light intensity is weakened, it will no longer be detected as synchronous light, so there is The following problem: If you observe for a long time, although there is no object A to be detected, the output will repeat Hi and Lo, and it seems that there is vibration and the above object A is detected incorrectly

However, even if noise is detected in the middle, the count is cleared by inputting a clear signal to the CLR of the shift register 2J, and the output of the shift register 2J is still inverted to Hi

[0015] When external disturbance light as noise from the inverter fluorescent lamp continues to enter such as shown in FIG. 8(a) and FIG. 8(b), the following problems arise: Figure 11 The output F2 of the shift register 2J shown in Fig.

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