Abstract: An ink-cooled thermal ink jet printhead has an efficient heat exchanger located on the back side of the printhead that eliminates the need for heat sinks. All ink flowing to the firing chamber goes through the heat exchanger. The geometry of the heat exchanger is chosen so that almost all the residual heat absorbed by the printhead substrate is transferred to the ink as it flows to the firing chamber. Additionally, the pressure drop of the ink flowing through the heat exchanger is low enough so that it does not significantly reduce the refill rate of the firing chambers. The heat exchanger can have one or more active heat exchanger sides. The heat exchanger has little thermal mass itself and significantly reduces the thermal mass of printhead by eliminating the need for a heat sink. This reduces the warm-up time of the printhead to a fraction of a second.

Abstract: The present invention provides a new and novel method for locking software programs to a particular disk. The method includes the steps of creating several files, one with a fixed name and at least one other file having a random name. Saving the head, cylinder and sector information for each of the files in the corresponding file along with use count information, saving the names of all the files in the first file with the fixed name, and encrypting all the files. This program locking method permits the distribution of trial copies of software programs and limits the risk that the program will be copied or used more than the permitted number of times.