Method and apparatus for printing with ink drops of varying sizes using a drop-on-demand ink jet print head

Claim 3

A method according to claim 1 in which the parameter is the duration of the wait period.

Claim 4

A method according to claim 1 in which the parameter is the duration of the ejection pulse component.

Claim 5

A method according to claim 1 in which the parameter is the duration of the ejection pulse component and further comprising the step of varying the duration of the wait period to vary the volume of the ink in the ink drops.

Claim 6

A method according to claim 1 in which the ink is phase charge ink.

Claim 7

A method according to claim 1 in which the refill pulse component is of a duration which is less than one-fifth of the time period of the natural resonance frequency of the ink meniscus.

Claim 10

A drop-on-demand ink jet head assembly for applying an ink drop having a volume to a print medium spaced from the ink jet head assembly, the ink having a meniscus with a resonance frequency having a time period, the ink jet head assembly comprising: chamber means for containing ink, the chamber means being coupled to an ink drop orifice having an outlet; a drive signal circuit that produces a drive signal that includes a bipolar electric pulse with refill and ejection pulse components of voltages of opposite relative polarity which are separated by a wait period, the ejection pulse component having an amplitude and a duration and the wait period having a duration, the ejection pulse component following the wait period and the refill pulse component, the refill pulse component having a fixed amplitude and a fixed duration which is less than about one-fifth of the time period of the resonance frequency of the meniscus; and acoustic drive means receiving the drive signal for producing a pressure wave in the ink in response to the drive signal to cause a portion of the ink to pass outwardly through the ink drop orifice and outlet and form the ink drop, the ink drop traveling from the outlet toward the print medium, the volume of the ink drop being responsive to a parameter of the drive signal.

Claim 11

A drop-on-demand ink jet head assembly for applying an ink drop having a volume to a print medium spaced from the ink jet head assembly, the ink having a meniscus with a resonance frequency having a time period, the ink jet head assembly comprising: chamber means for containing ink, the chamber means being coupled to an ink drop orifice having an outlet; a drive signal circuit that produces a drive signal that includes a bipolar electric pulse with refill and ejection pulse components of voltages of opposite relative polarity which are separated by a wait period, the ejection pulse component having an amplitude and a duration and the wait period having a duration, the ejection pulse component following the wait period and the refill pulse component, the refill pulse component having a fixed amplitude and a fixed duration which is less than about one-fifth of the time period of the resonance frequency of the meniscus; and acoustic drive means receiving the drive signal for producing a pressure wave in the ink in response to the drive signal to cause a portion of the ink to pass outwardly through the ink drop orifice and outlet and form the ink drop, the ink drop traveling from the outlet toward the print medium, the volume of the ink drop being responsive to a parameter of the drive signal.

Claim 12

The ink jet head assembly of claim 8 in which the parameter is the duration of the wait period.

Claim 13

The ink jet head assembly of claim 8 in which the parameter is the duration of the ejection pulse component.

Claim 14

The ink jet head assembly of claim 8 in which the parameter is the duration of the ejection pulse component and in which the volume of the ink drop is responsive to the duration of the wait period.

Claim 15

A drop-on-demand ink jet head assembly for applying an ink drop having a volume to a print medium spaced from the ink jet head assembly, the ink having a meniscus with a resonance frequency having a time period, the ink jet head assembly comprising: chamber means for containing ink, the chamber means being coupled to an ink drop orifice having an outlet; a drive signal circuit that produces a drive signal that includes a bipolar electric pulse with refill and ejection pulse components of voltages of opposite relative polarity which are separated by a wait period, the ejection pulse having a duration and an amplitude and the wait period having a duration, the ejection pulse component following the wait period and the refill pulse component, the refill pulse component having a fixed amplitude and a fixed duration which is less than about one-fifth of the time period of the resonance frequency of the meniscus; and acoustic drive means receiving the drive signal for producing a pressure wave in the ink in response to the drive signal to cause a portion of the ink to pass outwardly through the ink drop orifice and outlet and form the ink drop, the ink drop traveling from the outlet toward the print medium after at least one of the bipolar electric pulses has been received, the volume of the ink drop being responsive to the number of bipolar electric pulses received by the drive means.

Claim 16

A drop-on-demand ink jet head assembly for applying an ink drop having a volume to a print medium spaced from the ink jet head assembly, the ink having a meniscus with a resonance frequency having a time period, the ink jet head assembly comprising: chamber means for containing ink, the chamber means being coupled to an ink drop orifice having an outlet; a drive signal circuit that produces a drive signal that includes a bipolar electric pulse with refill and ejection pulse components of voltages of opposite relative polarity which are separated by a wait period, the ejection pulse having a duration and an amplitude and the wait period having a duration, the ejection pulse component following the wait period and the refill pulse component, the refill pulse component having a fixed amplitude and a fixed duration which is less than about one-fifth of the time period of the resonance frequency of the meniscus; and acoustic drive means receiving the drive signal for producing a pressure wave in the ink in response to the drive signal to cause a portion of the ink to pass outwardly through the ink drop orifice and outlet and form the ink drop, the ink drop traveling from the outlet toward the print medium after at least one of the bipolar electric pulses has been received, the volume of the ink drop being responsive to the number of bipolar electric pulses received by the drive means.

Claim 17

The ink jet head assembly of claim 12 in which 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 until a selected number of the bipolar drive pulses have been applied.

Claim 18

The ink jet head assembly of claim 12 in which the bipolar electric pulses are separated from each other by no more than about one hundred microseconds.

Claim 19

The ink jet head assembly of claim 12 in which 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 20

The ink jet head assembly of claim 12 in which the bipolar electric pulses are separated from one another by a time period of from about thirty to about one hundred microseconds.