A method for managing printing of data by a thermal printer. The thermal printer includes a thermal print head. The thermal print head has a plurality of points, each point having an effective resistance r.sub.d, and is powered by a power source. The method includes the following actions: measuring a voltage U given by the power source of the thermal printer; measuring an internal resistance r.sub.u of the power source; and computing a duration t for heating a number n of points as a function of the voltage U of the power source, the internal resistance r.sub.u of the power source, at least one effective resistance r.sub.d of at least one point corresponding to a dot to be printed for the printing of the data and as a function of at least one value of parasitic resistance r.sub.p of at least one element of the thermal printer.

A thermal printer has a thermal head with multiple heat elements for printing on roll paper; a measurer that measures heat element resistance; printer memory storing a resistance evaluation table relating the resistance of the heat elements to heat element defect levels defined based on a specific range of reflectivity in the symbol image; and an evaluator that references the resistance evaluation table stored in printer memory, acquires a defect level based on the resistance measured by the measurer, and evaluates the defect state of the thermal head based on the defect level of a consecutively adjacent count of heat elements.

A method for managing printing of data by a thermal printer. The thermal printer includes a thermal print head. The thermal print head has a plurality of points, each point having an effective resistance r.sub.d, and is powered by a power source. The method includes the following actions: measuring a voltage U given by the power source of the thermal printer; measuring an internal resistance r.sub.u of the power source; and computing a duration t for heating a number n of points as a function of the voltage U of the power source, the internal resistance r.sub.u of the power source, at least one effective resistance r.sub.d of at least one point corresponding to a dot to be printed for the printing of the data and as a function of at least one value of parasitic resistance r.sub.p of at least one element of the thermal printer.

An apparatus for determining the resistance of a printing element of a print head, the apparatus comprising: a print head comprising a plurality of individually controllable printing elements connected in parallel, and a capacitor connected in parallel with the printing elements; a test voltage supply arranged to supply a test voltage to the print head; a current monitor arranged to measure the current supplied to one of the printing elements when the said one of the printing elements is connected to the test voltage supply; and a controller arranged to determine the resistance of the said one of the printing elements based upon the measured current.

According to an embodiment, an image forming apparatus according to an embodiment determines whether or not it is necessary to check for malfunctions on a basis of a priority setting for each image region in a print image. Further, the image forming apparatus executes a malfunction check using a check circuit on a heating element that has been determined to need to be subjected to a malfunction check.