Inkdrop-volume test using heat-flow effects, for thermal-inkjet printers
US5714989A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 22, 1993 |
| Grant date | Feb 3, 1998 |
| Priority date | — |
| Expiry date | Nov 22, 2013 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB41J2/17566
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
The invention provides methods of determining ink volume ejected from a printhead, controlling ejected volume, and warning of low ink supply. A printhead is fired to eject ink: this operating step includes heating the ink and head; carrying away heat, in the ejected volume, from the head; and conveying a volume of cooler ink to the head, from a supply, to replace the ejected ink. The method finds the head cooling caused by the carrying-away and conveying; and to this applies a known calibration to find the volume ejected. The heating is roughly equal to that which occurs in printing. Besides the operating step, the method preferably includes finding (a) printhead cooling due to static mechanical thermal drain alone, and (b) printhead thermal response to warming by the same amount of heat as used to fire the pen in the operating step--but without ink ejection. These baseline values are used with the cooling observed in the operating step to isolate the effect of ink ejection and so find the cooling more accurately. The warming can be done by applying electrical energy to printhead-firing resistors, at pulse widths narrower than used for firing--but greater frequency--to inject power…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.