Ink jet print head and ink jet printer

• US 5,627,575 A
• Filed: 07/28/1994
• Issued: 05/06/1997
• Est. Priority Date: 11/30/1993
• Status: Expired due to Fees

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Ishida, Nobuhisa, Fujimoto, Hisayoshi
• Primary Examiner(s): Bobb, Alrick
• Application Number:
  US08/281,693
• Time in Patent Office: 1,013 Days
• Field of Search: 347/40, 347/70, 347/94
• US Class Current: 347/40
• CPC Class Codes: B41J 2/15 for serial printing

Abstract

In order to provide an ink jet print head effectively ensuring a stable print quality or capable of reducing the voltage applied to piezoelectric: elements while maintaining the volume displacement of the pressure chambers, and to provide an ink jet printer using the same, the ink jet print head of the present invention comprises a plurality of pressure chambers circularly arranged in a hounds tooth manner for allowing the passage of ink, and a plurality of ink flow paths acting as flow paths for ink flowing from the pressure chambers. It further comprises a diaphragm defining one surface of the pressure chambers, and a plurality of piezoelectric elements which apply a pressure to the pressure chambers to discharge the ink within the pressure chambers from the nozzle through the ink flow paths for printing. The pressure chambers disposed in the external portion of the hounds tooth arrangement have a circumferential length equal to or greater than that of the pressure chambers disposed in the internal portion of the hounds tooth arrangement, and have a radial length equal to or smaller than that of the latter.

Claims

1. An ink jet print head, comprising:

a plurality of nozzles capable of ejecting ink toward an object;

at least two sets of pressure chambers, each set comprising a plurality of pressure chambers circularly or arcuately arranged around said nozzles, with each pressure chamber having a shape defined by a circumferential length and a radial length;

a plurality of ink flow paths communicating said pressure chambers with corresponding ones of said nozzles;

a diaphragm defining one surface of said pressure chambers, said diaphragm capable of vibrating to apply a pressure to said pressure chambers, thereby causing the ink within said pressure chambers to be discharged from said nozzles by way of said ink flow paths; and

a plurality of piezoelectric elements attached to an external surface of said diaphragm to thereby vibrate said diaphragm,

wherein a first, outer set of said at least two sets of pressure chambers is disposed radially outside a second, inner set of said at least two sets of pressure chambers, said first set of pressure chambers having (i) a circumferential length equal to or greater than a circumferential length of said second set of pressure chambers, and (ii) a radial length equal to or smaller than a radial length of said second set of pressure chambers.

2. An ink jet print head according to claim 1, wherein said diaphragm is made of a photosensitive glass.

3. An ink jet print head according to claim 1, wherein said diaphragm substantially covers said pressure chambers.

4. An ink jet print head according to claim 1, wherein said diaphragm is substantially equal in size to said piezoelectric elements.

5. An ink let printer including an ink jet print head according to claim 1.

6. An ink jet print head according to claim 1, wherein the pressure chambers in said first set of pressure chambers have a circumferential length equal to or greater than the radial length thereof.

7. An ink jet print head according to claim 1, wherein the pressure chambers in said second set of pressure chambers have a radial length equal to or greater than the circumferential length thereof.

8. An ink jet printer including an ink jet print head according to claim 6.

9. An ink jet printer including an ink jet print head according to claim 7.

10. An ink jet print head, comprising:

a plurality of ink nozzles capable of ejecting ink toward an object;

at least two sets of pressure chambers, each set comprising a plurality of pressure chambers disposed in a circular arrangement around said nozzles and a plurality of ink flow paths in fluid communication with the pressure chambers which supply the ink to corresponding nozzles;

a diaphragm defining a wall of said pressure chambers; and

a plurality of piezoelectric elements capable of deforming said diaphragm in response to an application of voltage for changing a volume of corresponding pressure chambers;

wherein the at least two sets of pressure chambers are arranged in a concentric circular arrangement and further wherein the pressure chambers of a first set of said at least two sets of pressure chambers on a radially outer circle are in an alternate arrangement relative to the pressure chambers of a second set of said at least two sets of pressure chambers on a radially inner circle.

11. An ink jet print head according to claim 10, wherein said pressure chambers of said first set have ink flow paths extending between said pressure chambers of said second set, wherein said ink flows paths lead to said corresponding nozzles.