Ling intensity detection method and light intensity detection circuit

Abstract

The invention relates to a light intensity detection method and a light intensity detection circuit. According to the method, photo-generated current generated by a photographic module is amplified and is used for controlling the frequency of an oscillator, thereby the change of the photo-generated current is converted into change of the output frequency of the oscillator; and the strength of light can be detected by only detecting the output frequency of the oscillator, so that the light intensity can be detected more simply and conveniently. In addition, the light intensity detection circuit adopting the light intensity detection method comprises the photo-generated module, a current amplifying and comparing module and the oscillator; and the circuit has the advantages of more simplified structure, reduced power consumption and reduced chip area occupied by the circuit.

Description

technical field [0001] The invention relates to the field of electronics, in particular to a light intensity detection method and a light intensity detection circuit. Background technique [0002] The current smart card or dual-interface card has been developed more and more rapidly. For safety considerations, light detection is also required. Portable products also need to detect the intensity of light in order to save power on the display screen. There are two types of current light intensity detection implementation schemes: one is to use a photodiode to detect the light signal, generate a current, and detect the light intensity through a current comparison method; the other is to use a photodiode to detect the light signal and generate a current. Light intensity is detected by converting a current through a resistor into a voltage. figure 1 It is a light intensity detection circuit in the prior art. Such as figure 1 As shown, the light intensity detection circuit inc...

AI Technical Summary

Problems solved by technology

[0004] 1) Using the method of current comparison to detect light intensity requires more reference current options, sacrifices more power consumption, and the implementation of the control circuit is more complicated;

[0005] 2) The method of converting current to voltage is used to detect light intensity. Since the current generated by light induction is relatively small, to generate a larger voltage for detection, the current needs to be amplified, and the current needs to flow through a relatively large resistance. It will consume more power consumption and occupy a larger chip area;

[0006] 3) Using a separate photodiode to achieve light intensity detection or a special photosensitive device, the cost is relatively high or the compatibility of the process is relatively poor

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