Patent ID: 7311374
Filing Date: 2007-12-25
Classification: B41J

Abstract:
1. A liquid discharge cartridge integrally having a liquid discharge head discharging liquid, and a liquid container containing liquid supplied to the liquid discharge head, comprising: in the liquid container, a sensor for detecting residual liquid amount in the liquid container; and in the liquid discharge head, detection means of detecting the residual liquid amount in the liquid container using the sensor, judgment means of judging presence of the residual liquid amount in the liquid container on the basis of an output from the detection means, and outputting zero residual liquid amount information when judging that there is no residual liquid amount in the liquid container, and nonvolatile memory means of storing zero residual liquid amount information when the zero residual liquid amount information is outputted from the judgment means, wherein the sensor contains at least two electrodes which face each other; wherein the detection means includes an oscillation circuit to which electrostatic capacitance generated between the electrodes is connected as a load, and which oscillates a pulse signal whose oscillation frequency varies according to change of the electrostatic capacitance caused by presence of liquid between the electrodes, wherein the sensor includes three plate electrodes of which first and second plate electrodes are adjacent mutually, and of which a third plate electrode is located such that a space is left where liquid in the liquid container may flow in between the first and third plate electrodes, and such that the third plate electrode faces the first and second plate electrodes; and wherein the oscillation circuit is connected to one of the first and second plate electrodes and another electrode is connected to ground potential.