Latching serial data in an ink jet print head

摘要

A print data loading circuit receives N bits of serial data on a serial input data line, and provides the input data to a data bus in an addressing circuit for addressing one or more image-forming elements in a printing device. The data loading circuit includes an N-bit serial shift register having N number of serially-coupled single-bit storage registers. The data loading circuit also includes N-1 number of data latches, each having a data input coupled to a data output of a corresponding one of the single-bit storage registers. The data outputs of the data latches are coupled to N-1 number of selection lines that are coupled to the data bus. Each data latch has a clock input that is coupled to the data output of the Nth storage register. Based on this configuration, a bit provided at the Nth-register data output acts as a load trigger bit to cause the other data bits in the other single-bit storage registers to be loaded into the N-1 number of data latches. By providing the trigger bit from the Nth register of the shift register, the present invention eliminates the need for a second clock input to latch the print data into the data latches. Eliminating a second clock input reduces print head costs and potential EMI problems.