Pressure regulated free-ink ink-jet pen

• US 5,736,992 A
• Filed: 08/24/1995
• Issued: 04/07/1998
• Est. Priority Date: 10/31/1994
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: HP Inc.
• Inventors: Pawlowski, Norman E. Jr.
• Primary Examiner(s): Metjahic, Safet
• Assistant Examiner(s): Chizmar, John
• Application Number:
  US08/518,847
• Time in Patent Office: 957 Days
• Field of Search: 347/7, 347/85, 347/86, 347/87
• US Class Current: 347/7
• CPC Class Codes: B41J 2/175 Ink supply systems ; Circuit parts therefor
• CPC Class Codes: B41J 2/17503 Ink cartridges
• CPC Class Codes: B41J 2/17513 Inner structure
• CPC Class Codes: B41J 2/17523 Ink connection
• CPC Class Codes: B41J 2/17553 Outer structure
• CPC Class Codes: B41J 2/17556 Means for regulating the pressure in the cartridge
• CPC Class Codes: B41J 2/17566 Ink level or ink residue control
• CPC Class Codes: B41J 2/17596 Ink pumps, ink valves
• CPC Class Codes: B41J 2002/17516 comprising a collapsible ink holder, e.g. a flexible bag
• CPC Class Codes: G01F 23/003 with a probe suspended by rotatable arms with floats G01F23/32
• CPC Class Codes: G01F 23/72 using magnetically actuated indicating means

Abstract

The present invention relates to free-ink type ink-jet pens. A spring-loaded regulator mechanism is provided within the pen to allow ink from a pressurized ink reservoir to be fed to the pen while maintaining a predetermined set point back-pressure at the printhead as needed for appropriate pen operation. A mechanism in communication with the ambient atmosphere is used in conjunction with a substantially constant force biasing mechanism to maintain the balance between the countervailing forces. Back-pressure is maintained substantially constant regardless of the ink flow rate from the ink reservoir into the pen.

Claims

1. An ink-jet pen apparatus, adapted for use with an ink reservoir having a mechanism for supplying ink from said ink reservoir to said ink-jet pen apparatus at a predetermined feed pressure, said ink-jet pen apparatus comprising:

a pen body having an ink containment chamber;

an ink-jet printhead mechanism coupled to said pen body and in fluidic communication with said ink containment chamber;

coupling means for coupling said ink containment chamber to said ink reservoir; and

regulating means, mounted within said ink containment chamber and coupled to said coupling means, for regulating flow of ink into said ink containment chamber from said ink reservoir and for maintaining a predetermined, substantially constant, back-pressure set point at said ink-jet printhead during varying ink flow rates from said ink reservoir into said ink containment chamber via said coupling means, wherein said regulating means further includes valve means for varying ink flow rate and shutting off ink flow from said ink reservoir into said ink containment chamber, biasing means, having a substantially constant bias force during varying ink flow rates from said ink reservoir into said ink containment chamber, coupled to said valve means, for biasing said valve means toward a closed condition, means for opening and closing said valve means in response to a pressure differential between ambient atmospheric pressure and said predetermined back-pressure set point, including a valve seat for opening and closing said valve means, a valve seat mount, having said valve seat mounted thereon, wherein said biasing means is coupled to said valve seat mount, holding said valve seat in a position closing said valve means until the biasing force is overcome by ambient atmospheric pressure and wherein said biasing means further includes a spring having a substantially constant spring force, and at least one inflatable bag member mounted on said valve seat mount and coupled to ambient atmospheric, pressure such that said bag member inflates and deflates in response to the pressure differential between ambient atmospheric pressure and said predetermined back-pressure set point.

2. The apparatus as set forth in claim 1, further comprising:

adjusting means for adjusting the predetermined back-pressure set point.

3. An ink-jet pen device for a hard copy apparatus including an ink reservoir means for providing ink under pressure greater than or equal to atmospheric pressure to said pen device and a means for delivering print media to said pen device, said ink-jet pen device comprising:

printhead means for transferring droplets of ink to said print media during printing operation of said hard copy apparatus;

ink containing means, having said printhead means mounted thereon, for containing an on-board supply of ink for said printhead means such that said printhead means has a predetermined on-board volume of ink available; and

regulating means, enclosed within said ink containing means, for regulating flow of ink from said ink reservoir means into said ink containing means and for maintaining a predetermined, substantially constant, back-pressure at said printhead means during varying ink flow rates from said ink reservoir means into said ink containing means, wherein said regulating means further includes valving means for controlling the flow of ink from said ink reservoir means into said ink containing means, a spring, coupled to said valving means and having a substantially constant bias force, for controlling said valving means in response to a force due to a pressure differential between ambient atmospheric pressure and said substantially constant bias force, and a bag member, mounted for expanding and contracting in response to a pressure differential between ambient atmospheric pressure and said substantially constant bias force such that said valving means opens as ambient atmospheric pressure force exceeds said substantially constant bias force.

4. The device as set forth in claim 3, further comprising:

adjusting means for adjusting said substantially constant bias force to a predetermined bias force set point to establish a predetermined back-pressure set point at said printhead.

5. The device as set forth in claim 3, wherein said regulating means further comprises:

leverage means, coupled to said spring, having a valve seat located thereon to open and close said valving means.

6. The device as set forth in claim 3, wherein said spring further comprises:

at least one torsion spring.

7. The device as set forth in claim 3, wherein said spring further comprises:

at least one negator spring.