Recording medium determination device, image formation device, and recording medium determination method

A recording medium determination method in which a recording medium determination device is used, the recording medium determination device including a light emitter that emits inspection light to a recording medium, and a light detector that detects incident light including at least one of diffuse reflected light of the inspection light emitted to the recording medium or fluorescent light excited by the inspection light in the recording medium, the recording medium determination method comprising:

• making a determination depending on a property of the recording medium based on a detection result of first incident light of the incident light in accordance with first inspection light of the inspection light and second incident light of the incident light in accordance with second inspection light of the inspection light obtained by the light detector,
• wherein
• the first inspection light has an intensity whose peak wavelength is more than or equal to 750 nm and less than or equal to 1100 nm,
• the second inspection light has an intensity whose peak wavelength is shorter than the peak wavelength of the first inspection light, and
• wherein
• the determination depending on the property is based on a ratio between a first value in accordance with an amount of the first incident light received by the light detector and a second value in accordance with an amount of the second incident light received by the light detector.

A recording medium determination device comprising:

• three or more light emitting elements that emit inspection light respectively having specific wavelengths to a recording medium;
• a hardware processor that causes the three or more light emitting elements to sequentially emit the inspection light;
• and
• a light receiving element that receives light having been emitted from the three or more light emitting elements,
• wherein the hardware processor
• determines a type of the recording medium from a relative relationship between an amount of received light concerning a light emitting element used as a reference among the three or more light emitting elements and an amount of received light concerning each of the light emitting elements other than the light emitting element used as the reference, and
• causes the light emitting element used as the reference to emit the inspection light in a turn other than first and last turns in a sequence of causing the three or more light emitting elements to emit the inspection light, wherein the light emitting element used as the reference has an intensity of a peak wavelength more than or equal to 750 nm and less than or equal to 1100 nm.