Head device for ink jet printer

Claim 2

A printing head for an ink-on-demand ink jet printer comprising: an intermediate plate, said intermediate plate having formed in opposed surfaces thereof a plurality of individual pressure chambers for holding ink and a duct associated with each said pressure chamber, said ducts leading to an edge of said intermediate plate; a pair of vibration plates attached to said intermediate plate with one vibration plate on each of said opposed surfaces of said intermediate plate, a common surface on each said vibration plate spanning all of said plurality of pressure chambers on the associated surface of each intermediate plate; a plurality of electromechanical transducing means attached to said vibration plates for deflecting said vibration plates locally when said transducing means are driven, each one of said plurality of transducing means being in registry with an individual one of said pressure chambers; and means for feeding ink to said pressure chambers including an inlet feed reservoir for providing ink to said pressure chambers, said reservoir comprising a spacer position between said vibration plates, said vibration plates extending beyond said intermediate plate, said spacer being spaced away from said intermediate plate whereby said reservoir is formed between said spacer, said intermediate plate and said vibration plates, said combination of plates forming substantially closed pressure chambers and ducts leading to nozzles at said edge, and driving and transducing means reducing the capacity of said registered chamber, causing at least a portion of the ink contents of said registered chamber to be expelled through said associated nozzle.

Claim 3

A printing head as claimed in claim 1, wherein said means for feeding ink to said pressure chambers comprise grooves in said intermediate plate, said grooves being of different lengths, said grooves having an island therein, the length and width of said island determining the impedance to flow of fluid from said associated nozzles, whereby every nozzle can be made to eject the same quantity of ink when driven.

Claim 4

A printing head as claimed in claim 1, wherein said dimensions adapted to provide uniform flow include the length, width and shapes and contours of said flow channels.

Claim 5

A printing head for an ink-on-demand ink jet type printer comprising: an intermediate plate, said intermediate plate having formed in opposed surfaces thereof a plurality of individual pressure chambers for holding ink and a duct associated with each said pressure chamber, said ducts leading to an edge of said intermediate plate, said pressure chambers being at different distances from said edge, each said duct being adapted to provide the same flow impedance to ink between said pressure chambers and said edge; a pair of outer plates attached to said intermediate plate with one outer plate on each of said opposed surfaces of said intermediate plate, a common surface on each said outer plate spanning all of said plurality of pressure chambers on the associated surface of each intermediate plate; a plurality of electromechanical transducing means attached to said outer plates for deflecting said outer plates locally when said transducing means are driven, each one of said plurality of transducing means being in registry with an individual one of said pressure chambers; and a plurality of supply channels for feeding ink to said pressure chambers individually, said supply channels being formed in said opposed surfaces of said intermediate plate, each said supply channel having a high impedance portion, the flow impedance in said channel entering each said associated pressure chamber differing from the flow impedance in said duct exiting from said associated pressure chamber and leading to said edge, the impedance of each said duct being less than the impedance of said supply channel to said associated pressure chamber; said combination of plates forming substantially closed pressure chambers and ducts leading to nozzles at said edge, and driving a transducing means reduces the capacity of said registered chamber, causing at least a portion of the ink contents of said registered chamber to be expelled through said associated nozzle, the quantity of ink from each said nozzle being equal.

Claim 6

A printing head for an ink-on-demand ink jet type printer comprising: an intermediate plate, said intermediate plate having formed in opposed surfaces thereof a plurality of individual pressure chambers for holding ink and a duct associated with each said pressure chamber, said ducts leading to an edge of said intermediate plate, said pressure chambers being at different distances from said edge, each said duct being adapted to provide the same flow impedance to ink between said pressure chambers and said edge; a pair of outer plates attached to said intermediate plate with one outer plate on each of said opposed surfaces of said intermediate plate, a common surface on each said outer plate spanning all of said plurality of pressure chambers on the associated surface of each intermediate plate; a plurality of electromechanical transducing means attached to said outer plates for deflecting said outer plates locally when said transducing means are driven, each one of said plurality of transducing means being in registry with an individual one of said pressure chambers; and a plurality of supply channels for feeding ink to said pressure chambers individually, said supply channels being formed in said opposed surfaces of said intermediate plate, each said supply channel having a high impedance portion, the flow impedance in said channel entering each said associated pressure chamber differing from the flow impedance in said duct exiting from said associated pressure chamber and leading to said edge, the impedance of each said duct being less than the impedance of said supply channel to said associated pressure chamber; said combination of plates forming substantially closed pressure chambers and ducts leading to nozzles at said edge, and driving a transducing means reduces the capacity of said registered chamber, causing at least a portion of the ink contents of said registered chamber to be expelled through said associated nozzle, the quantity of ink from each said nozzle being equal.