Inspection device, printer, and method to inspect images accurately

A printer comprising:

• a conveyor configured to convey a printing medium in a conveyance direction;
• a print head configured to perform printing on the printing medium;
• a reader comprising a light source and a light receiving element, the reader being disposed downstream of the print head in the conveyance direction;
• a white reference section;
• a memory storing reference data of a white pixel value;
• and
• a controller configured to:
• cause the light source to emit light toward the white reference section, and receive a pixel signal output from the reader when the light receiving element receives reflected light from the white reference section, the pixel signal concerning a pixel value according to a light quantity of the reflected light received by the light receiving element;
• determine a rate of decrease in the pixel value relative to the reference data, based on the received pixel signal;
• when the rate of decrease is equal to or higher than a first threshold, output an instruction signal concerning an instruction to clean the reader;
• after outputting the instruction signal, again receive a pixel signal output from the cleaned reader when the light receiving element of the cleaned reader receives reflected light from the white reference section to re-determine the rate of decrease in response to receiving input of a completion signal concerning completion of cleaning of the reader;
• and
• update the reference data using the re-determined rate of decrease.

A method implementable on an inspection device, the inspection device comprising a reader comprising a light source and a light receiving element, a white reference section, and a memory storing reference data of a white pixel value, the method comprising:

• causing the light source to emit light toward the white reference section, and receive a pixel signal output from the reader when the light receiving element receives reflected light from the white reference section, the pixel signal concerning a pixel value according to a light quantity of the reflected light received by the light receiving element;
• determining a rate of decrease in the pixel value relative to the reference data, based on the received pixel signal;
• when the rate of decrease is equal to or higher than a first threshold, outputting an instruction signal concerning an instruction to clean the reader;
• after outputting the instruction signal, again receive a pixel signal output from the cleaned reader when the light receiving element of the cleaned reader receives reflected light from the white reference section to re-determining the rate of decrease in response to receiving input of a completion signal concerning completion of cleaning of the reader;
• and
• updating the reference data using the re-determined rate of decrease.