EP0205243A2
Expired / Lapsed
EP
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Control apparatus for an on-demand ink jet printing element
Assignee: Olivetti SpA
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Filing: 1986-04-22
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Granted: —
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Expires: 2006-04-22
Abstract
Abstract U7 In an ink jet printing element in which the drop is expelled by generating a current pulse through the ink in the nozzle, in order to reduce the control voltage, a first pulse (Tr) for heating the ink is generated, followed by a vaporization pulse (Tv) with a delay such as to make the printing position independent of the direction of movement of the element with respect to the paper. The heating pulse (Tr) is generated by a circuit (31) controlled by a temperature sensor (34) so that the duration of the heating pulse has a negative temperature coefficient. The vaporization pulse (Tv) is generated by a circuit (32) manually controlled (potentiometer 39) to determine the pulse duration on the basis of the desired strength of the printing. The delay between the two pulses is controlled by a delay circuit (38), e.g. a monostable circuit. The two pulses are applied to a transformer (35) which generates the voltage between the electrodes. The two circuits (31, 32) may be constituted by one monostable circuit with separate RC networks sequentially enabled for determining the durations of the heating and vaporization pulses.
Inventors
- 👤 Roberto Realis Luc
- 👤 Alessandro Crotti
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 10:43
CPC Classifications
B; B41; B41J; B41J2/00; B41J2/005; B41J2/01; B41J2/015; B41J2/04; B41J2/045; B41J2/04501; B41J2/04541; B41J2/04563; B41J2/0458
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
190 words
Control apparatus for an on-demand ink jet printing element, in which printing is effected by producing from a logic signal an electrical current such as to increase the temperature of the ink disposed in a nozzle (18), in which a first pulse (Tr) is generated to raise the temperature of the ink in the nozzle to close to the vaporization point and a second pulse (Tv) is generated to create a bubble of vapour in the nozzle so as to cause a drop of ink to be expelled through the nozzle, characterised in that the ink is electrically conductive and-the pulses (Tr, Tv) generate current between a first electrode (22) in contact with the ink and a second electrode (23) disposed adjacent the outlet edge of the nozzle (18), and in that it comprises a first circuit (31 or 64, 63) controlled by a logic signal (C or D) and operable to produce the first pulse (Tr) of a duration which is inversely proportional to temperature, and a second circuit (32 or 66, 63) which is controlled by the logic signal by way of a delay circuit (3R or 52).
Claim 2
Dependent Claim
190 words
Control apparatus for an on-demand ink jet printing element, in which printing is effected by producing from a logic signal an electrical current such as to increase the temperature of the ink disposed in a nozzle (18), in which a first pulse (Tr) is generated to raise the temperature of the ink in the nozzle to close to the vaporization point and a second pulse (Tv) is generated to create a bubble of vapour in the nozzle so as to cause a drop of ink to be expelled through the nozzle, characterised in that the ink is electrically conductive and-the pulses (Tr, Tv) generate current between a first electrode (22) in contact with the ink and a second electrode (23) disposed adjacent the outlet edge of the nozzle (18), and in that it comprises a first circuit (31 or 64, 63) controlled by a logic signal (C or D) and operable to produce the first pulse (Tr) of a duration which is inversely proportional to temperature, and a second circuit (32 or 66, 63) which is controlled by the logic signal by way of a delay circuit (3R or 52).
Claim 3
Dependent Claim
34 words
Apparatus according to claim 1, characterised by manually adjustable means (3 q or 72) for varying the duration of the second pulse (Tv) in order to vary the strength of printing of the element.
Claim 4
Dependent Claim
55 words
Apparatus according to claim 1 or 2, characterised in that the first (31 or 64, 63) and second (32 or 66, 63) circuits control the printing element by way of a transformer (35) whose secondary winding emits voltage pulses of a value corresponding to the duration of the pulses (Tr, Tv) provided by the circuits.
Claim 5
Dependent Claim
87 words
Apparatus according to claim 1, 2 or 3, comprising a generator for generating strobe signals corresponding to the print positions of the element, characterised in that the delay circuit (52) provides a delay such that the second pulse (Tv) produces the emission of a drop at a time which is equidistant in respect of time from the time at which two consecutive strobe signals are generated, whereby printing is synchronized by the strobes independently of the direction of movement of the element with respect to the paper.
Claim 6
Dependent Claim
26 words
Apparatus according to claim 4, characterised in that the delay circuit (52) comprises a monostable circuit and an adjustable RC coupling (53) for determining the delay.
Claim 7
Dependent Claim
73 words
Apparatus according to claim 4 or 5, characterised in that the first and second circuits each comprise a potentiometer (67, 72) for regulating the duration of the respective pulses, the potentiometers being coupled in sequence to a common capacitor (69) under the control of the delay circuit (52) to cause the first and second pulses (Tr, Tv) to be emitted by a second monostable circuit (63) with durations determined by the respective potentiometers.
Claim 8
Dependent Claim
60 words
Apparatus according to claim 6, characterised in that the second monostable circuit (63) actuates a switch (73) connected to the primary winding of a transformer (35) whose secondary winding is connected to the first and second electrodes (22, 23), the secondary winding emitting voltage pulses of a value corresponding to the duration of the first and second pulses (Tr, Tv).
Claim 9
Dependent Claim
40 words
R. Apparatus according to claim 7, characterised in that the second monostable circuit (63) also controls a circuit (74) for damping the oscillations of the primary winding of the transformer (35) in between the first and second pulses (Tr, Tv).
References Cited (Backward Citations)
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