Thermal printing method and thermal printer

Claim 2

A thermal printing method, comprising the steps, for each of plural thermal elements (51, 52) disposed on a printing head (1), a step of inverting data (D l ) printed in a preceding print cycle, a step of obtaining a logical product of the inverted data (D 2 ) resulting from said inverting step and data (D 3 ) to be printed in the instant print cycle, and a step of pre-heating each of said thermal elements in dependence on said logical product.

Claim 3

A thermal printing method according to claim 1, wherein said thermal elements (51, 52) are divided into two groups along the direction in which said printing head (1) is moved, and said thermal elements are alternately driven on the group basis.

Claim 4

A thermal printer, comprising: a) a printing head (1) disposed movably for printing operation; b) a plurality of thermal elements (51, 52) disposed on said printing head; and c) printing head drivers (54, 55) mounted on said printing head, each of said drivers including a first register (105) for storing data (D 1 ) to be printed and outputting said data in parallel, a second register (103) for storing the data outputted in parallel from said first register and outputting said data after having been inverted, a logical product circuit (101) for determining logical product (D 4 ) of the parallel outputs of said first and second registers for each data, and switching means for interrupting currents flowing to said thermal elements corresponding to each data in dependence on the logical product determined for each data.

Claim 5

A thermal printer, comprising: a) a printing head (1) disposed movably for printing operation; b) a plurality of thermal elements (51, 52) disposed on said printing head; and c) printing head drivers (54, 55) mounted on said printing head, each of said drivers including a first register (105) for storing data (D 1 ) to be printed and outputting said data in parallel, a second register (103) for storing the data outputted in parallel from said first register and outputting said data after having been inverted, a logical product circuit (101) for determining logical product (D 4 ) of the parallel outputs of said first and second registers for each data, and switching means for interrupting currents flowing to said thermal elements corresponding to each data in dependence on the logical product determined for each data.

Claim 6

A thermal printer according to claim 3, 'wherein said plurality of thermal elements (51, 52) are classified into a first group of thermal elements (51) and a second group of thermal elements (52) along the direction in which said printing head (1) travels, the individual thermal elements of each group being aligned in a row in the direction perpendicular to the traveling direction of said printing head, the thermal elements (51, 52) of said first and second groups being driven alternately with each other.

Claim 7

A thermal printer according to claim 3, wherein said first register is constituted by a shift register having a data input terminal and a clock input terminal, said second register being constituted by data latches (103) each provided for each data and having a latch input terminal and a latch reset input terminal to which respective inputs are applied through associated inverters (109, 111), said switching means being constituted by NAND circuits each having a strobe input terminal to which a strobe signal is applied through an inverter (107).