| (19) |
 |
|
(11) |
EP 0 317 171 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
|
18.07.1990 Bulletin 1990/29 |
| (43) |
Date of publication A2: |
|
24.05.1989 Bulletin 1989/21 |
| (22) |
Date of filing: 10.11.1988 |
|
|
| (84) |
Designated Contracting States: |
|
DE FR GB IT |
| (30) |
Priority: |
13.11.1987 US 120300
|
| (71) |
Applicant: Hewlett-Packard Company |
|
Palo Alto,
California 94304 (US) |
|
| (72) |
Inventors: |
|
- Leban, Marzio A.
Corvallis
Oregon 97330 (US)
- Allen, Ross R.
San Diego, CA 92131 (US)
- Bhaskar, Eldurkar V.
Corvallis
Oregon 97330 (US)
|
| (74) |
Representative: Williams, John Francis et al |
|
WILLIAMS, POWELL & ASSOCIATES
34 Tavistock Street
London WC2E 7PB
London WC2E 7PB (GB) |
|
| |
|
| (54) |
Integral thin film injection system for thermal ink jet heads and methods of operation |
(57) A novel thermal ink jet printhead and related methods of operation are described.
Methods of manufacture of the printhead wherein multiple heater resistors (18,20)
are connected in series between a source of ink supply (10) and an output ink ejection
orifice (24). A primary heater resistor (20) is located in an ink ejection chamber
(16) and adjacent an output ink ejection orifice (24). This resistor (20) propels
ink away from the printhead, whereas another heater resistor (18) (or resistors) is
removed from the primary heater resistor (20) and is located in an adjacent ink injection
chamber (14), and is operative to inject ink toward the primary heater resistor (20).
In this manner, ink ejection operational frequency is increased and cavitational wear
on the heater resistors (20) is minimized. Simultaneously, hydrodynamic back pressure
in the ink ejection chamber (16) is reduced, and control over ink drop size and viscosity
is improved.