Integrated charge and orifice plates for continuous ink jet printers
An integrated orifice array plate and a charge plate are fabricated for a continuous ink jet print head by producing an orifice plate and a charge plate, and by bonding the two together. The orifice plate is produced by providing an electrically non-conductive orifice plate substrate, forming a recessed-surface trench of predetermined depth into one of two opposed sides of the orifice plate substrate, and forming an array of orifices through the orifice plate substrate from the recessed surface of the trench to the other of the two opposed sides wherein the orifices are spaced apart by a predetermined distance. The charge plate is produced by providing an electrically non-conductive orifice plate substrate of predetermined thickness, and forming a plurality of charging leads on one of two opposed sides of the orifice plate substrate. The charge leads are spaced apart by said predetermined distance.
1. A method for integrally fabricating an orifice array plate and a charge plate for a continuous ink jet printer print head, said method comprising the steps of:
a. producing an orifice plate by:
providing an electrically non-conductive orifice plate substrate,
forming a recessed-surface trench of predetermined depth into one of two opposed sides of the orifice plate substrate, and
forming an array of orifices through the orifice plate substrate from the recessed surface of the trench to the other of the two opposed sides wherein said orifices are spaced apart by a predetermined distance;
b. producing a charge plate by:
providing an electrically non-conductive charge plate substrate of predetermined thickness, and
forming a plurality of charging leads on one of two opposed sides of the charge plate substrate, said charge leads being spaced apart by said predetermined distance; and
c. bonding the other of the two opposed sides of the charge plate substrate to said one side of the orifice plate substrate such that the charging leads align respectively with the orifices of the array and are spaced there from by the depth of the trench and the thickness of the orifice plate substrate.
2. A method for integrally fabricating an orifice array plate and a charge plate as set forth in claim 1 , wherein:
the one of the two opposed sides of the orifice plate substrate is initially coated with a silicon nitride layer; and
the orifices are formed by etching into the orifice plate substrate through openings in the silicon nitride layer on the one side of the orifice plate substrate.
3. A method for integrally fabricating an orifice array plate and a charge plate as set forth in claim 1 , wherein:
the one of the two opposed sides of the orifice plate substrate is initially coated with a silicon nitride layer; and
the trench is formed by etching into the orifice plate substrate through openings in the silicon nitride layer on the one side of the orifice plate substrate.
4. A method for integrally fabricating an orifice array plate and a charge plate as set forth in claim 1 , wherein:
the one of the two opposed sides of the orifice plate substrate is initially coated with a silicon nitride layer;
the orifices are formed by etching into the orifice plate substrate through openings in the silicon nitride layer on the one side of the orifice plate substrate; and
the trench is formed by etching into the orifice plate substrate through openings in the silicon nitride layer on the one side of the orifice plate substrate.
5. A method for integrally fabricating an orifice array plate and a charge plate as set forth in claim 1 , wherein the charging leads are formed by:
coating the one of the two opposed sides of the charge plate substrate with a silicon nitride layer and then a conductive layer;
electroforming charging leads on the conductive layer; and
isolating the charging leads one from the others.
6. A method for integrally fabricating an orifice array plate and a charge plate as set forth in claim 1 , wherein the thickness of the charge plate substrate is selected to meet desired droplet break-off lengths.
7. The method of claim 1 wherein the step of forming an orifice plate further comprises the step of forming an ink channel the other side of the orifice plate substrate.
8. A method for integrally fabricating an orifice array plate and a charge plate as set forth in claim 7 , wherein the ink channel is formed by:
coating the other side of the orifice plate substrate with a silicon nitride layer; and
etching into the orifice plate substrate through an opening in the silicon nitride layer on the other side of the orifice plate substrate.
9. An integral orifice array plate and charge plate for a continuous ink jet printer print head, comprising:
a. an orifice plate having:
an electrically non-conductive orifice plate substrate,
a trench of predetermined depth on one of two opposed sides of the orifice plate substrate, and
an array of orifices through the orifice plate substrate from the trench to the other of the two opposed sides, said orifices being spaced apart by a predetermined distance; and
b. a charge plate having:
an electrically non-conductive charge plate substrate of predetermined thickness, and
a plurality of charging leads on one of two opposed sides of the charge plate substrate, said charge leads being spaced apart by said predetermined distance, wherein the other of the two opposed sides of the charge plate is anodically bonded to said one side of the orifice plate substrate such that the charging leads align respectively with the orifices of the array and are spaced there from by the depth of the trench and the thickness of the orifice plate substrate.
10. An integral orifice array plate and charge plate as set forth in claim 9 wherein the orifice plate further comprises an ink channel the other side of the orifice plate substrate.
11. An integral orifice array plate and charge plate as set forth in claim 9 wherein the thickness of the charge plate substrate is selected to meet desired droplet break-off lengths.