US 5,671,002 AGranted

Print head with multiplexed resistances controlling supply of current to image blocks

AssigneeKYOCERA Corporation

InventorShunji Murano

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Abstract

In an LED head operated on a time sharing basis, a multiplexer switches resistances for determining LED currents on LED arrays and assigns appropriate resistance to each array. The multiplexer is operated by block select signals of a block select circuit for time sharing operation, where the number of resistances corresponds to the number of blocks. The multiplexer capacity may also be less than the number of blocks, where the number of resistances less than the number of blocks and the same resistances correspond to more than one block. Output dispersions between arrays are adjusted by appropriate assignment of the resistances. sharing operation. Capacity of the multiplexer correspond to the number of blocks required for time. Gray scale printing is achieved by switching the current determining resistances in accordance with shading degree of image with the multiplexer.

Claims14

Dependent claims

A print head comprising:

a plurality of image blocks, each of said image blocks including a plurality of image formation modules,
a driving circuit for driving said plurality of image blocks, one block at a time,
block select means for connecting said plurality of image blocks with said driving circuit, block by block, in a first, predetermined order,
a plurality of resistances for determining the output of said driving circuit, said plurality of resistances being connectable to said driving circuit in any one of a plurality of different resistance configurations so that each of the configurations determines a respectively different driving circuit output, and
switching means for connecting said resistances to the driving circuit in successive ones of said different resistance configurations in a second predetermined order, one of the resistance configurations being connected to the driving circuit during driving of one image block, and each of the connected resistance configurations reducing differences between image formation module outputs from one block to another.

2 more elements

A print head for printing an image, the image being composed of a succession of horizontal lines, each of said horizontal lines being divided into a plurality of sub-lines, which are offset from one another in a vertical scanning direction, said print head comprising:

printing means having a plurality of image formation modules, arranged parallel to the horizontal line, for printing the plurality of sub-lines of each line in sequence,
print data providing means for providing print data for each one of said image formation modules individually for each of said sub-lines,
means for generating multiplexer control signals representing the sequence of printing of the sub-lines of each line,
a driving signal generating circuit coupled to said print data providing means and said printing means for providing each one of said image formation modules with driving signals that turn on/off according to said print data, the driving signals for each line having a magnitude, and
switch means for controlling the driving signal generating circuit to change the magnitude of the driving signals during printing of each one of said sub-lines for each of said sub-lines, said switch means including a multiplexer connected to a plurality of resistances to receive the multiplexer control signals and operative in response to the multiplexer control signals for changing an individual resistance configuration for each of said sub-lines.

2 more elements

Dependencies are inferred from the claim text.