Out of ink detector for a thermal inkjet printer
US5699090A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 31, 1994 |
| Grant date | Dec 16, 1997 |
| Priority date | — |
| Expiry date | Oct 31, 2014 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB41J2/17566
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
When a thermal inkjet print cartridge operates to eject ink, three things happen at once: (1) heating by the heating resistor with flow of heat into the ink chamber; (2) cooling by heat drain toward the reservoir, print cartridge body and to ambient; and (3) cooling by carrying away of heat in the ink drops and replacement by cooler ink from the reservoir. The present invention is a method of detecting a depleted ink supply by monitoring the temperature of the printhead substrate with a temperature sensitive resistive trace on the printhead surface. When the print cartridge is warmed with warming pulses to a temperature higher than its normal operating temperature: and then firing pulses are implemented to eject ink, the temperature measured by the thermal sense resistor will decrease if the print cartridge is ejecting its normal, or nearly normal, amount of ink. If the print cartridge is ejecting less than its normal amount of ink the temperature will decrease less, stay the same, or even increase. It is this temperature increase or decrease that is used as an ink ejection detector. The method is quickly and readily performed by a printer before printing or between printing interv…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.