EP0437062A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method and apparatus for printing with a drop-on-demand ink jet print head using an electric field
Assignee: Tektronix Inc
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Filing: 1990-12-14
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Granted: —
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Expires: 2010-12-14
Abstract
Abstract A drop-on-demand ink jet has an ink chamber (12) coupled to a source of ink (14), and an ink drop orifice (16) with an outlet (18). An acoustic driver (30) produces a pressure wave in the ink and causes the ink to pass outwardly through the ink drop orifice and outlet (18). A high voltage electric field is oriented to accelerate ink drops along a path from the outlet to print medium (20). The electric field is time invariant and is the only electric field present along the path during drop formation and accelaration. The size of the ink drops may be varied, such as by driving the acoustic driver with varying drive signals. One preferred form of acoustic drive signal comprises of individual or combinations of plural bipolar drive pulses. The combination of energy imparted by the acoustic driver (30) and the electric field accelerates small and large drops such that the time for the drops to travel to the print medium (20) is substantially the same. The ink jet printer of the present invention may be used to print with a wide variety of inks, including phase change inks.
Inventors
- 👤 Joy Roy
- 👤 Susan C. Schoening
- 👤 Hue P. Le
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 10:26
CPC Classifications
B; B41; B41J; B41J2/00; B41J2/005; B41J2/01; B41J2/21; B41J2/2121; B41J2/2128
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
207 words
A method of operating a drop-on-demand ink (10) jet of the type having an ink chamber (12) coupled to a source (14) of ink, an ink drop orifice (16) with an outlet (18), the ink drop orifice (16) being coupled to the ink chamber (12), acoustic drive means (32) for producing a pressure wave in the ink to cause ink to pass outwardly through the ink drop orifice (16) and outlet (18), and in which ink drops travel in a first direction along a path from the outlet (18), toward print medium (20) spaced from the outlet (18), the method comprising operating the acoustic drive means (32) to cause ink to pass from the outlet (18) and into a high voltage electric field oriented to accelerate ink drops along the path from the outlet (18) toward the print medium (20), the electric field pulling the ink passing from the outlet (18) and assisting in breaking off of ink passing from the outlet (18) to form an ink drop, and the electric field accelerating the so-formed ink drop toward the print medium (20) characterized in that the electric field is maintained time invariant and as the only electric field present along the path during drop formation and acceleration.
Claim 2
Dependent Claim
65 words
A method as claimed in Claim 1 in which the drop-on-demand ink jet (10) is capable of producing drops of a first minimum size without establishing the electric field, the method comprising the step of operating the drive means (30) with the electric field established such that the drop-on-demand ink jet (10) produces drops of a second minimum size smaller than the first minimum size.
Claim 3
Dependent Claim
103 words
A method as claimed in Claim 1 or Claim 2 in which the drop-on-demand ink jet (10) is capable of operation with a substantially constant drop travel time from the outlet (18) to the print medium (20) up to a first maximum repetition rate without establishing the electric field, the method comprising the step of operating the drive means (30) with the electric field established such that the drop-on-demand ink jet (10) operates with a substantially constant drop travel time from the outlet (18) to the print medium (20) up to a second maximum repetition rate greater than the first maximum repetition rate.
Claim 4
Independent Claim
97 words
A method as claimed in any one of Claims 1 to 3 in which the acoustic drive means (30) is operated so as selectively to vary the volume of ink that emerges from the outlet (18) into the electric field and thereby the volume of ink drops travelling along the path toward the print medium (20), the electric field accelerating the various volume ink drops such that drops of various sizes require substantially the same amount of time to travel to the print medium, the various volume drops being used to accomplish grey scale or half-tone printing.
Claim 5
Independent Claim
533 words
A method as claimed in any preceding claim in which the drive means (30) comprises a piezoelectric drive means for expanding and contracting the volume of the ink chamber (12), the acoustic driver (30) being driven in one of the following ways:― (i) the acoustic driver (30) is driven with at least one bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, the duration of the wait period being varied so as to vary the volume of the ink drops; (ii) the acoustic driver (30) is driven with a bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, the duration of the ejection pulse being varied so as to vary the volume of the ink drops; (iii) the acoustic driver (30) is driven with a bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period the duration of the wait period and the duration of the ejection pulse being varied so as to vary the volume of the ink drops; (iv) the acoustic driver (30) is driven with at least one bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, the amplitude of the ejection pulse being varied so as to vary the volume of the ink drops; (v) the acoustic driver (30) is driven with at least one bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, the ratio of the pulse duration of the ejection pulse component to the pulse width of the refill pulse component being varied so as to vary the volume of ink drops; (vi) the acoustic driver (30) is driven with at least one bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, the ratio of the amplitude of the ejection pulse component to the amplitude of the refill pulse component being varied so as to vary the volume of ink drops; (vii) the acoustic driver (30) is driven with at least one bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, the number of bipolar pulses used to form the drops being varied so as to vary the volume of ink in the ink drops; (viii) the acoustic driver (30) is driven with at least one unipolar electric pulse, the duration of unipolar drive pulses being varied so as to vary the volume of ink in the ink drops; (ix) the acoustic driver (30) is driven with at least one unipolar electric pulse, the amplitude of the unipolar drive pulses being varied so as to vary the volume of ink in the ink drops; or (x) the acoustic driver (30) is driven with at least one unipolar electric pulse, the duration and the amplitude of the unipolar drive pulses being varied so as to vary the volume of ink in the ink drops.
Claim 6
Independent Claim
16 words
A method as claimed in any preceding claim in which the ink is phase change ink.
Claim 7
Dependent Claim
62 words
A method as claimed in any preceding claim in which the drop-on-demand ink jet (10) comprises an array of a plurality of ink drop orifices (16) each with an orifice outlet (18), the electric field being a common electric field downstream of the orifice outlets (18) and addressing them all, the array being operated in accordance with the steps of Claim 1.
Claim 8
Independent Claim
28 words
A method as claimed in any preceding claim wherein the ink is a phase change or other ink having a resistivity of from 10⁻⁴ ohm-cm to 10⁻¹¹ ohm-cm.
Claim 9
Dependent Claim
19 words
A method as claimed in Claim 8 wherein the ink has a resistivity of 10⁻⁶ ohm-cm to 10⁻⁸ ohm-cm.
Claim 10
Independent Claim
52 words
A method as claimed in any preceding claim wherein the electric field is established by an electrode (42) spaced from the ink drop orifice outlet (18) by a gap (G), the electric field being within the range of from about 750 volts per millimeter of the breakdown voltage across the gap (G).
Claim 11
Independent Claim
84 words
A method as claimed in any preceding claim wherein the drive means (30) comprises a piezoelectric drive means for expanding and contracting the volume of the ink chamber (12), the driver (30) being supplied with at least one bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period and the number of bipolar pulses used to form the drops being varied so as to vary the volume of ink in the ink drops.
Claim 12
Dependent Claim
49 words
A method as claimed in Claim 11 wherein the bipolar electric pulses are separated from each other by a time period which is insufficient to cause the breaking off of a drop at the orifice outlet (18) until a selected number of the bipolar drive pulses have been applied.
Claim 13
Dependent Claim
25 words
A method as claimed in Claim 11 wherein the bipolar electric pulses are separated from each other by no more than about one hundred microseconds.
Claim 14
Dependent Claim
35 words
A method as claimed in Claim 11 wherein the bipolar electric pulses are separated from one another by a time period of at least about two times the duration of an individual bipolar electric pulse.
Claim 15
Dependent Claim
30 words
A method as claimed in Claim 11 wherein the bipolar electric pulses are separated from one another by a time period of from about forty to about one hundred microseconds.
Claim 16
Independent Claim
55 words
A method as claimed in any preceding claim wherein the electric field is established by electric field-generating means (42) whose output is adjustable to vary the strength of the electric field from a first level for a first type of print medium (20) to a second level for a second type of print medium (20).
Claim 17
Dependent Claim
142 words
A drop-on-demand ink jet print head (10) for ejecting a drop of ink along a path of travel from the ink jet print head (10), across a gap (G), and to print medium (20), the ink jet print head (10) comprising an ink chamber (12); a member (38) defining an ink drop ejection orifice (16) in communication with the ink chamber (12), the ink drop orifice (16) having an outlet (18); acoustic drive means (30) for causing ink to pass from the outlet (18); and means (42) for establishing a high voltage electric field along at least a portion of the path for pulling ink passing from the outlet (18), for assisting in forming a drop of ink, and for accelerating the travel of ink drops to the print medium (20), the electric field being time invariant during drop formation and acceleration.
Claim 18
Dependent Claim
22 words
A print head as claimed in Claim 17 and including means for selectively varying the volume of ink in the ink drops.
Claim 19
Dependent Claim
53 words
A print head as claimed in Claim 17 or Claim 18 wherein the means (42) for establishing the high voltage electric field is so arranged as in use to establish an electric field oriented to accelerate ink drops towards the print medium (20) as the sole orientation of electric fields along the path.
Claim 20
Dependent Claim
113 words
A print head as claimed in any one of Claims 17 to 19 and including means (32, 34) for passing a body of ink outwardly through the outlet (18) such that the electric field draws the body of ink into the configuration of a filament (52) and means for retracting a portion of the body of ink adjacent to the orifice (16) to sever the body of ink into a body portion (52) outside the outlet (18) and a body portion (50) which is inside the orifice (16) thereby to form a drop of ink, the electric field causing the drop to accelerate across the gap (G) and toward the print medium (20).
Claim 21
Dependent Claim
81 words
A print head as claimed in any one of Claims 17 to 20 wherein the drive means (30) comprises a piezoelectric drive means for expanding and contracting the volume of the ink chamber (12), the drive means (30) including means (32) for driving the drive means with a bipolar electric drive pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period as to vary the volume of ink in the ink drops.
Claim 22
Dependent Claim
24 words
A print head as claimed in any one of Claims 17 to 21 and comprising an array of orifices (16) and orifice outlets (18).
Claim 23
Dependent Claim
47 words
A print head as claimed in any one of Claims 17 to 22 wherein the means for establishing an electric field comprises means for establishing an electric field of a magnitude within the range from 750 volts per millimeter to the breakdown voltage across the gap (G).
Claim 24
Dependent Claim
124 words
A print head as claimed in any one of Claims 17 to 23 wherein the means for establishing an electric field includes an electrode (42) positioned with the print medium (20) between the electrode (42) and the orifice outlet (18), the print head (10) having an orifice plate (38) defining the orifice outlet (18), the orifice plate (38) being generally in a first plane, the electric field being established in a direction normal to the first plane and between the orifice plate (38) and the electrode (42), the apparatus including means for adjusting the strength of the electric field to a first level for a first type of print medium (20) and to a second level for a second type of print medium (20).
Claim 25
Dependent Claim
167 words
A print head as claimed in any one of Claims 17 to 24 and configured and arranged for ejecting a plurality of drops of ink along paths of travel from nozzles (16) in an array of nozzles of the print head (10), the paths extending from the print head nozzles, across a gap (G) and to print medium (20), the print head (10) comprising plural ink chambers (12); a member (38) which defines plural ink drop ejecting orifices (16), each orifice (16) being in communication with a respective associated ink chamber (12) and each of the orifices (16) having an outlet (18); acoustic drive means (30) for causing ink to pass from the outlets (18); and means (42) for establishing a common high voltage electric field for pulling ink passing from the outlets (18) in use, for assisting in forming drops of ink and for accelerating the travel of ink drops of the print medium (20), the electric field being time invariant during drop formation and acceleration.
References Cited (Backward Citations)
No citation records indexed.
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