Liquid ejection apparatus, and ejection state determination apparatus

An ejection state determination apparatus for determining an ejection state of a liquid ejection head, the liquid ejection head including (1) a heat generating resistance element, (2) a temperature detection element that detects temperature corresponding to the heat generating resistance element, and (3) an ejection port provided in correspondence with the heat generating resistance element, the liquid ejection head being configured to eject liquid from the ejection port by driving of the heat generating resistance element, the ejection state determination apparatus comprising:

• an output unit configured to output a value in accordance with a detection output from the temperature detection element;
• a threshold setting unit configured to set a determination threshold for determining the ejection state of the liquid ejection head using the first energy, the determination threshold being set based on (1) a first output value outputted from the output unit in a case where the heat generating resistance element is driven with first energy in an ejection state in which the liquid is ejected from the ejection port and (2) a second output value estimated to be outputted from the output unit assuming the heat generating resistance element is driven with the first energy in a non-ejection state in which the liquid is not ejected;
• and
• a determination unit configured to determine the ejection state by comparing an output value outputted from the output unit in a case where the heat generating resistance element is driven with the first energy with the determination threshold,
• wherein the threshold setting unit estimates the second output value by using (1) an output value outputted from the output unit in an event where the heat generating resistance element is driven with second energy in the non-ejection state and (2) a relation between output values outputted from the output unit in an event where the heat generating resistance element is driven and values of energy used to obtain the respective output values, which is measured in advance in the non-ejection state.