Coffee makers

Abstract

A coffee maker includes a water reservoir, a drip case for containing coffee powder, a heating pipe for heating water fed from the water reservoir through one of two ends thereof and for feeding hot water to the drip case from the other end, a heater for applying heat to the heating pipe through a heat-transferring plate to cause the hot water to flow through the heating pipe to the end communicating to the drip case, by the force of boiling pressure, a temperature sensor for sensing the temperature of the heat-transferring plate, a first comparator for deciding a time period required to increase the temperature of the heat-transferring plate to reach a predetermined value, in response to a decision signal from the temperature sensor, and a second comparator for comparing the time period decided by the first comparator with a predetermined value to produce an alarm signal in case that the time period decided by the first comparator takes a smaller value than the predetermined value. Accordingly, when the effective cross sectional area of the heating pipe is decreased to a large extent owing to the affixing of the incrustations and the like, a user is automatically alarmed.