Global Patent Index - EP 0541064 A3

EP 0541064 A3 19930721 - THERMAL PRINT HEAD UNIT

Title (en)

THERMAL PRINT HEAD UNIT

Publication

EP 0541064 A3 19930721 (EN)

Application

EP 92118896 A 19921104

Priority

US 78781091 A 19911104

Abstract (en)

[origin: EP0541064A2] The invention provides a thermal printer with a removable print head unit having a multitude of very small resistance heating elements for printing small dots or pixels (e.g., 300 pixels per inch) of an image. Minor variations in the printing characteristics of the multitude of individual head elements are electronically compensated for to achieve uniform print densities for that head unit. Print compensation data in the form of correction numbers respective to each resistance element of the print head are permanently stored in a low cost device, such as an electronically erasable programmable read only memory (EEPROM), which is furnished as an integral part of the removable head unit. Each such head unit is uniquely calibrated by its permanently stored correction numbers to achieve uniform printing action so that for all intents and purposes all such head units perform the same in any printer. Any head unit may be operated in a given thermal printer without further adjustment to the printer. When the printer is powered-up, the correction numbers unique to the head unit then installed in the printer are automatically loaded into the high speed memory and compensation circuits of the printer. This arrangement greatly simplifies the replacement of the head unit of a printer in the field. <IMAGE>

IPC 1-7

B41J 2/36

IPC 8 full level

B41J 2/355 (2006.01); B41J 2/35 (2006.01); B41J 2/36 (2006.01); B41J 25/34 (2006.01)

CPC (source: EP)

B41J 2/36 (2013.01); B41J 25/34 (2013.01)

Citation (search report)

Designated contracting state (EPC)

DE FR GB

DOCDB simple family (publication)

EP 0541064 A2 19930512; EP 0541064 A3 19930721; JP H07186430 A 19950725

DOCDB simple family (application)

EP 92118896 A 19921104; JP 28901192 A 19921027