Optical sensor and output circuit thereof

Abstract

An optical sensor is provided according to an embodiment of the present disclosure. The optical sensor includes a first photodiode, a second photodiode having characteristics different from characteristics of the first photodiode, filters configured to block or transmit a specific wavelength range of the light, and an output circuit configured to correct a sensitivity deviation, which may be caused when one of the filters is used for the first photodiode, based on a sensitivity deviation, which may be caused when the other filter of the same kind as the one filter is used for the second photodiode, and output only the specific wavelength range of the light.

What is claimed is: 
     
         1 . An optical sensor comprising:
 a fifth photodiode including a first transmission filter formed on a light receiving surface of the fifth photodiode;   a sixth photodiode including a second transmission filter formed on a light receiving surface of the sixth photodiode; and   an output circuit configured to subtract an output of the sixth photodiode from an output of the fifth photodiode,   wherein the first and second transmission filters are configured to transmit a specific wavelength range of the light and the sixth photodiode has characteristics different from characteristics of the fifth photodiode.   
     
     
         2 . The optical sensor of  claim 1 , wherein, when the output of the sixth photodiode is subtracted from the output of the fifth photodiode, areas of the fifth and sixth photodiodes are adjusted in advance such that a value of current in a wavelength range other than the specific wavelength range becomes zero. 
     
     
         3 . The optical sensor of  claim 1 , wherein, when the output of the sixth photodiode is subtracted from the output of the fifth photodiode, a calculation method in the output circuit is adjusted in advance such that a value of current in a wavelength range other than the specific wavelength range becomes zero. 
     
     
         4 . The optical sensor of  claim 1 , wherein the output circuit is further configured to correct a sensitivity deviation that is caused when the first transmission filter is used for the fifth photodiode, based on a sensitivity deviation that is caused when the second transmission filter is used for the sixth photodiode. 
     
     
         5 . The optical sensor of  claim 1 , wherein the specific wavelength range is an UV wavelength range. 
     
     
         6 . The optical sensor of  claim 1 , wherein the output circuit includes:
 an arithmetic circuit;   an ADC; and   a logic circuit,   wherein the arithmetic circuit is configured to subtract the output of the sixth photodiode from the output of the fifth photodiode and pass a result of the calculation over the ADC.   
     
     
         7 . An output circuit comprising:
 an arithmetic circuit which is connected to a fifth photodiode including a first transmission filter formed on a light receiving surface the fifth photodiode, and a sixth photodiode including a second transmission filter formed on a light receiving surface of the sixth photodiode, and configured to subtract an output of the sixth photodiode from the output of the fifth photodiode;   a conversion circuit configured to convert an analog signal from the arithmetic circuit into a digital signal; and   a logic circuit configured to subject the digital signal from the conversion circuit to a predetermined calculation process,   wherein the first and second transmission filters are configured to transmit a specific wavelength range of the light and the sixth photodiode has characteristics different from characteristics of the fifth photodiode.   
     
     
         8 . The output circuit of  claim 7 , wherein, when the output of the sixth photodiode is subtracted from the output of the fifth photodiode, areas of the fifth and sixth photodiodes are adjusted in advance such that a value of current in a wavelength range other than the specific wavelength range becomes zero. 
     
     
         9 . The output circuit of  claim 7 , wherein, when the output of the sixth photodiode is subtracted from the output of the fifth photodiode, a calculation method is adjusted in advance such that a value of current in a wavelength range other than the specific wavelength range becomes zero.