Ink remaining amount detecting device, method for detecting ink remaining amount, and ink jet printing apparatus

An ink remaining amount detecting method for determining whether or not an amount of ink remaining in an ink tank is smaller than a predetermined amount, the method comprising:

• a control step of performing light emission control that switches, among two levels, an emission intensity of the light allowed to enter a reflector in which an optical reflectance obtained in a case where an amount of ink remaining in the ink tank is smaller than the predetermined amount is higher than an optical reflectance obtained in a case where an amount of ink remaining in the ink tank is equal to or larger than the predetermined amount;
• and
• a first determining step of determining whether or not a difference between output signals each output by a light receiving unit configured to receive light reflected by the reflector according to a corresponding each of at least two of the plurality of levels of light emission has reached a specific value,
• a switching step of switching an emission intensity of a higher level than the levels of the two light emissions in a case where the first determining step determines that the difference of the output signals has reached the specific value, and
• a second determining step of determining that an amount of remaining ink has reached the predetermined amount in a case where an output signal output by the light receiving unit according to light with the higher emission intensity has reached a preset threshold value.

An ink jet printing apparatus comprising an ink tank in which ink is stored, a print head that ejects ink fed from the ink tank, and ink remaining amount detecting unit configured to determining whether or not an amount of ink remaining in the ink tank is smaller than a predetermined amount,

• wherein the ink remaining amount detecting unit comprises:
• a reflector provided in the ink tank and in which an optical reflectance obtained in a case where an amount of ink remaining in the ink tank is smaller than the predetermined amount is higher than an optical reflectance obtained in a case where an amount of ink remaining in the ink tank is equal to or larger than the predetermined amount;
• light emitting unit configured to generate light allowed to enter the reflector;
• light receiving unit configured to receive light reflected by the reflector and outputting an output signal according to an amount of received reflected light;
• control unit configured to perform light emission control that switches an emission intensity of the light emitting unit among a plurality of levels;
• and
• determination unit configured to determine whether or not an amount of ink remaining in the ink tank has reached the predetermined amount based on an output signal output by the light receiving unit,
• wherein the determination unit determines whether or not a difference between output signals each output by the light receiving unit according to a corresponding each of at least two of the plurality of levels of light emissions has reached a specific value,
• the control unit switches an emission intensity of the light emitting unit to a higher level than the levels of the two light emissions in a case where the determination unit determines that a difference of output signals has reached the specific value, and
• the determination unit determines that an amount of remaining ink has reached the predetermined amount in a case where an output signal output by the light receiving unit according to light with the highest emission intensity generated by the light emitting unit has reached a preset threshold value.