Patent EP0200457A1 successfully refreshed from Google Patents.
EP0200457A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Control circuit for an ink jet printing element and a method of dimensioning and manufacture relating thereto
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 A control circuit (17) applies a voltage pulse to a piezoelectric transducer (16) to create pressure in a chamber (10) open to an ink reservoir (14) at one end and closed by an ink nozzle (13) at the other. The control circuit (17) generates a pulse formed by one or two waves, each comprising a secondary portion delayed relative to the primary portion by a time which is double the reflection time that is characteristic of the chamber (10), thereby cancelling reflection of the drop explusion pressure. The form of the wave is determined by a series of variable resistors disposed in the circuit while the time is regulated by an element for regulating the period of oscillation of the circuit. Alternatively the form of the wave is recorded in digital form in an ROM addressed by a counter while the period of oscillation is regulated by acting on a timer for controlling the counter.
Inventors
- 👤 Alessandro Scardovi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 19:53
CPC Classifications
B; B41; B41J; B41J2/00; B41J2/005; B41J2/01; B41J2/015; B41J2/04; B41J2/045; B41J2/04501; B41J2/04591; B41J2/04541; B41J2/04581; B41J2/04588; B41J2/055; B41J2/135; B41J2/14; B41J2002/14354
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
99 words
A control circuit for an on-demand ink jet printing element comprising a chamber (10) which is closed at one end by a capillary nozzle (13), and an electrical voltage transducer (16) for varying the pressure of the ink in the duct, the control circuit being adapted to generate a voltage pulse for each drop to be expelled, characterised in that the circuit comprises adjustable means (e.g. 42, 47, 48, 53) for varying the duration and the form of said pulse such that it can suppress the acoustic reflection waves of the pressure wave which produces expulsion of the drop.
Claim 2
Dependent Claim
99 words
A control circuit for an on-demand ink jet printing element comprising a chamber (10) which is closed at one end by a capillary nozzle (13), and an electrical voltage transducer (16) for varying the pressure of the ink in the duct, the control circuit being adapted to generate a voltage pulse for each drop to be expelled, characterised in that the circuit comprises adjustable means (e.g. 42, 47, 48, 53) for varying the duration and the form of said pulse such that it can suppress the acoustic reflection waves of the pressure wave which produces expulsion of the drop.
Claim 3
Dependent Claim
74 words
A circuit according to claim 1, characterised in that the said adjustable means are adjusted in such a way that the pulse has at least one self-cancelling wave formed by a primary portion and a secondary portion which is symmetrical with respect to the primary portion and delayed by a time equal to an even multiple of the time of reflection which is characteristic of the chamber (10), whereby the reflection waves are suppressed.
Claim 4
Dependent Claim
29 words
A circuit according to claim 2, characterised in that the pulse is formed by at least two superimposed self-cancelling waves which are phase-shifted in time by the said multiple.
Claim 5
Dependent Claim
37 words
A circuit according to claim 3, characterised in that the circuit is of the oscillating type to generate waves without harmonics, the said adjustable means being adjusted in such a way that the said multiple is two.
Claim 6
Dependent Claim
28 words
A circuit according to claim 4, characterised in that the adjustable means comprise a first adjusting element (42, 66) for varying the period of oscillation of the circuit.
Claim 7
Dependent Claim
69 words
A circuit according to claim 5, comprising a logic signal generator (G) for controlling the emission of the pulse, characterised in that the adjustable means comprise a second element (54) for regulating the duration of the logic signal in such a way as to produce phase distortion of the second of the waves, corresponding to the form of the end (12') of the printing element carrying the nozzle (13).
Claim 8
Dependent Claim
79 words
A circuit according to claim 5 or 6, characterised in that the adjustable means further comprise a first electrical resistor (53) for varying the amplitude of the pulse to adjust the speed of the drop, and at least one other electrical resistor (48) for adjusting the relationship between the positive peak and the negative peak of the pulse and creating a final connection of the wave to the feed voltage so as to attain critical damping of the pulse.
Claim 9
Dependent Claim
47 words
A circuit according to any of claims 5 to 7, wherein the circuit directly generates the voltage of the control wave, characterised in that the first element comprises a variable inductor (42) and the said other resistor (48) is disposed between the inductor and the transducer (16).
Claim 10
Dependent Claim
54 words
A circuit according to claim 8 characterised in that the transducer is disposed in parallel with a reference capacitor (49) and is connected to the said other resistor (48) by way of a high- gain amplifier (51), whereby the effect of the variations is its capacitance which are due to temperature is correspondingly reduced.
Claim 11
Dependent Claim
38 words
A circuit according to any of claims 5 to 7, characterised in that it generates a low voltage control pulse, an amplifier (73) being disposed between said transducer and the output of the circuit and the transducer (16).
Claim 12
Dependent Claim
45 words
A circuit according to claim 10, characterised in that the two waves of the pulse are generated by two corresponding operational amplifiers (64, 65) a third operational amplifier (67) being capable of generating the passage through zero of the pulse resulting from the two waves.
Claim 13
Dependent Claim
27 words
A circuit according to claim 11, characterised in that the said first element comprises a resistor (66) disposed between the first and second operational amplifiers (64, 65).
Claim 14
Dependent Claim
29 words
A circuit according to claim 11 or 12, characterised in that the said other resistor (72, 70) is capable of adjusting the gain of the first operational amplifier (64).
Claim 15
Dependent Claim
65 words
A circuit according to claim 5, characterised in that it comprises a read only memory (81) in which are recorded the digital values corresponding to the amplitude of the pulse at predetermined intervals of time, and a digital to analog converter (82) for generating and converting the digital values which are read out of the memory into voltage values for control of the transducer (16).
Claim 16
Dependent Claim
30 words
A circuit according to claim 14, characterised in that the voltage values are supplied at low voltage, an amplifier (73) being disposed between the converter (82) and the transducer (16).
Claim 17
Dependent Claim
38 words
A circuit according to claim 14 or 15, characterised in that the memory (81) is addressed by a counter (78) which can be enabled for counting by a logic print signal (80) and incremented by a timer (79).
Claim 18
Dependent Claim
29 words
A circuit according to claim 16, characterised by means for varying the frequency of the timer to adjust the duration of the control pulse in the individual printing element.
Claim 19
Dependent Claim
47 words
A circuit according to any of claims 10 to 17, characterised in that it feeds the transducer (16) by way of a two-stage amplification circuit (84, 86 or 88, 89) the low voltage stage (84 or 88) comprising means (87 or 91) for adjusting the gain thereof.
Claim 20
Dependent Claim
26 words
A circuit according to claim 18, characterised in that the high voltage stage (86) is formed by a pair of transistors which are disposed in series.
Claim 21
Dependent Claim
39 words
A circuit according to claim 18, characterised in that the high voltage stage is formed by a transformer (89) having a primary winding connected to the low voltage stage (88) and the secondary winding connected to the transducer (16).
Claim 22
Dependent Claim
39 words
A circuit according to any of claims 10 to 18, characterised in that it is capable of selectively feeding a series of transducers (16) for a multi-nozzle printing head such that the transducers can be excited simultaneously or sequentially.
Claim 23
Dependent Claim
38 words
A circuit according to claim 21, characterised in that a corresponding amplifier (73) is disposed between each transducer (16) and the circuit (17'), the various amplifiers being connected selectively to the circuit by means of a multiplexer (92).
Claim 24
Independent Claim
89 words
A method of dimensioning and manufacturing a control circuit for an electrical voltage transducer for actuating an on-demand ink jet printing element comprising a chamber (10) which is closed at one end by a capillary nozzle (13), characterised in that it comprises a phase for adjusting a series of elements of the circuit to define the preliminary values of these elements and a phase for fine adjustment of at least one of these elements of the circuit which is carried out on the circuit of the individual printing element.
Claim 25
Independent Claim
89 words
A method of dimensioning and manufacturing a control circuit for an electrical voltage transducer for actuating an on-demand ink jet printing element comprising a chamber (10) which is closed at one end by a capillary nozzle (13), characterised in that it comprises a phase for adjusting a series of elements of the circuit to define the preliminary values of these elements and a phase for fine adjustment of at least one of these elements of the circuit which is carried out on the circuit of the individual printing element.
Claim 26
Dependent Claim
72 words
A method according to claim 23, characterised in that the elements of the circuit are so adjusted as to generate a voltage pulse formed by at least one self-cancelling wave having a primary portion and a secondary portion which is symmetrical with respect to the primary portion and delayed by a time equal to an even multiple of the characteristic time of the duct, whereby the reflection of the pulse is cancelled.
Claim 27
Dependent Claim
41 words
A method according to claim 24, characterised in that the adjustment is carried out in such a way that the pulse is formed by the superimposition of at least two self-cancelling waves which are phase-displaced in time by the said multiple.
Claim 28
Dependent Claim
23 words
A method according to claim 25, characterised in that the adjustment is carried out in such a way that the multiple is two.
Claim 29
Dependent Claim
35 words
A method according to claim 23 to 26, characterised in that the adjustment operations are effected empirically by means of detection of the pressure that the pulse produces in the duct of the printing element.
Claim 30
Dependent Claim
37 words
A method according to claim 27, characterised in that the operation of adjusting the series of elements is effected in the design phase to define the respective dimensions so as to produce the form of the pulse.
Claim 31
Dependent Claim
44 words
A method according to claim 28, characterised in that the fine adjustment is carried out empirically at least on the individual printing element to vary the period of oscillation of the circuit, taking account of all the factors which influence the characteristic reflection time.
Claim 32
Dependent Claim
34 words
A method according to claim 28 or 29, characterised in that the adjustment operations are effected by sampling the pressure wave generated in the element with a pressure sensor formed by the same transducer.
Claim 33
Dependent Claim
31 words
A method according to claim 30, wherein the transducer is of piezoelectric type, characterised by means for enabling the piezoelectric element to sense the pressure and signal it to a monitor.
References Cited (Backward Citations)
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