CA1117815A - Ink jet printer control system - Google Patents
Ink jet printer control systemInfo
- Publication number
- CA1117815A CA1117815A CA000322267A CA322267A CA1117815A CA 1117815 A CA1117815 A CA 1117815A CA 000322267 A CA000322267 A CA 000322267A CA 322267 A CA322267 A CA 322267A CA 1117815 A CA1117815 A CA 1117815A
- Authority
- CA
- Canada
- Prior art keywords
- ink
- membrane
- pressure
- nozzle
- print head
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/015—Ink jet characterised by the jet generation process
- B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
- B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
- B41J2/055—Devices for absorbing or preventing back-pressure
Landscapes
- Particle Formation And Scattering Control In Inkjet Printers (AREA)
- Ink Jet (AREA)
Abstract
Abstract of the Disclosure A piezoelectric crystal is connected with a membrane and is energized to deflect or bend the membrane for ejecting droplets of ink from an ink supply. The energizing voltage pulses are timed to start and are of a duration whereby the return of the membrane to a normal position upon termination of the voltage pulses acts against the negative pressure wave in the ink supply for preventing excessive underpressure therein.
Description
7~
INK JET PRINTER CONTROL SYSTEM
Ba~ ound of the Invention _ _ _ _ In the field of non-impact printing, the most common types of printers have been the thermal printer and the ink jet printer. When the performance of a non-impact printer is compared with that of an impact printer, one of the problems in the non-impact machine has been the control of the printing operation.
As is well-known, the impact printing operation depends upon the movement of impact members typically by reason of an electromechanical system which is believed to enable a more precise control of such impact mambers.
The advent of non-impact printing as in the case of thermal printing brought out the fact that the heating cycle must be controlled in a manner to obtain maximum repeated operations. Likewise, the control of ink jet printing must deal with rapid starting and stopping movement of the ink fluid from a supply of such fluid.
Representative prior art in the field of ink jet printing includes United States Patent No.
3,747,120 issued to N. G. E. Stemme on July 17, 1973, which discloses an arrangement of writing mechanisms or that of applying droplets of ink in liquid form to a surface and wherein a chamber is divided into an inner portion and an outer portion with a channel connecting the portions. The inner portion is provided with a piezoelectric deYice for producing short duration pressure increases in the fluid in the chamber and an intake or supply channel is connected with the outer chamber portion for transmission of the fluid through a discharqe channel.
United States Patent No. 3,946,398 issued to E. L. Xyser et al on March 23, 1976 discloses method and apparatus for recording with writing fluids and droplet projection means wherein a print head :
~7~
includes a piezoelectric crystal plate connected with a membrane and char~ed with a voltage pulse which causes the crystal plate and the membrane to bend and to produce pressure oscillations in an ink-filled liquid chamber of the print head. Upon each occurrence of a first maximum pressure in the liquid, an ink droplet is ejected through a no~zle and deposited on a record medium. In order to insure a safe release of the ink droplet at a sufficient initial speed, the crystal must be charqed with a voltage pulse of sufficient height and width to bring about a respective maximum pressure in the liquid. A minimum pressure follows the maximum pressure in the liquid chamber and the chamber is again filled with ink so that by the ~ollowing energization pulse of the crystal plate, a sufficient maximum pressure is produced which causes the next ink droplet to be ejected from the nozzle It is especially at the hi~her ~requencies that the known ink jet print heads are working quite unreliably, since there may be an excessive or high underpressure arising or developing in the liquid chamber, which excessive underpressure causes cavitation or air bubbles to come into the liquid chamber by way of the nozzle. The forming of a vacuum in the supply or flow of the ink or the presence of air bubbles in the ink leads to trouble in the exact functioning of the print head and often results in a complete Eailure of the head.
Summary of the Inventlon The present invention relates to an ink jet printer and more particularly to a control system for such printer wherein a pulse-operated and responsive membrane produces increases in the pressure oE the liquid in the ink jet print head whereupon an ink droplet is ejected with each occurrence of a maximum increase in pressure. The control system includes a B~
drive element and is arranged to minimize or eliminate excessive underpressure conditions during the operation of the membrane caused by sudden increases and decreases in the presence of the ink fluid in the print head by reason of the pulsing and termination of pulsing of the drive element.
The ink is caused to flow from an ink supply through a passageway to a chamber adjacent the membrane which chamber is spaced from the nozzle of the print head so as to provide a precise amount of ink at the origin of the pressure-increasing device and thereby better control the effects from the changing pressures. An elongated chamber or passageway is routed from the supply chamber to a nozzle plate containing the nozzle through which the droplets of ink are ejected onto the record medium.
The logic means for generating voltage pulses for the drive element or piezoelectric element which deflects or bends the membrane is conditioned whereby the membrane is maintained by the drive element in a tensioned or pulsed state for a duration of time such that the underpressure resulting from the release of the membrane timely occurs either after or prior to the minîmum pressure following the maximum pressure condition. Another way of stating the above is that the logic circuit is provided to generate drive pulses for the membrane having a time duration such that the membrane is maintained in a tensioned or pulsed state for a sufficient length of time for the pressure decrease resulting ~rom the release of the membrane to tend to compensate the pressure fluctuation in the ink resulting from the initial driving movement of the membrane.
The invention is based on the knowledge that cavitation or forming of a vacuum in the ink and the occurrence of air bubbles in the ink chamber are possible conditions for the failure of an ink jet print head due to an excessive underpressure a~ter f~
the sudden pressure increase by the pulsing device.
The underpressure half wave occurs after the overpressure half wave which effects the ejection of the ink droplet. The overpressure shall in this application be understood to be that pressure exceeding the static pressure and the underpressure shall be understood as that pressure below the static pressure.
In view of the above discussion, the principal object of the present invention is to provide an ink jet printer having an improved print head arrangement enabling smoother operation of the print head in ejecting ink droplets, and wherein the printer functions in a safer condition and where the danger of cavitation and the formation of air bubbles in the liquid chamber is reduced.
Another object of the present invention is to provide an ink jet printer wherein the supply of ink is directed into position adjacent the ink pressure increasing device for reducing excessive pressure differentials between the ink supply and the ink ; nozzle.
An additional object of the present invention is to provide a control system for an ink jet printer which applies pulse energization of the pressure-increasing device for a duration of time to effectreduction of cavitation of the ink in the ink chamber.
A further object Gf the present invention is to provide an ink jet printer with a piezoelectric driven element and a control system therefor which is effective for reducing cavitation of ink and for eliminating forma~ion of air bubb~es in the ink chamber.
Another object of the present invention is to provide a control system for an ink jet printer which maintains a tensioned state of the pressure increasing device for a duration of time to effect reduction in back pressure and to dampen or compensate pressure differentials.
- s Additional advantages and features of the present invention will become apparent and fully understood from a reading of the following description, taken together with the annexed drawing.
Brief Description of the Drawin~
Fig. 1 is a diagrammatic representation of an ink jet printer incorporating the principles of the present invention;
Fig. 2 is a sectional view of an ink jet print head for use in the printer of Fig. l;
Fig. 3 is a block diagram of the ink jet printer according to Fig. l;
Fig. 4 illustrates a drive circuit for controlling the drive element of the membrane of the ink jet print head, and Figs. 5A-5E are pulse diagrams for the explanation of the mannner of functioning of the ink jet printer according to the present invention.
Descri~tlon of the Preferred Embodiment The use of equal elements, pressure values and time instances are each provided with the same reference number in the drawing so that the principle underlying the present invention is better comprehended from the following description.
Referring to Fig. 1, there is shown a simplified diagrammatic representation of an ink jet printer which functions according to the principle underlying the present invention. A record medium or paper 10 is caused to be driven from a record medium supply roll 12 past a printing station or line of printing zone 14 to a take-up roll 16. In a suitable position adjacent the record medium 10 is arranged an ink jet print head 18 from the nozzle of which are ejected droplets of ink which are caused to impinge on the record medium 10 upon the energization of the drive element oE the ink jet print head 18. For ~1~7~
reasons of clarity in the preferred embodiment, according to the present invention as described herein, there is shown one ink jet print head 18 which is arranged in stationary manner relative to the printing station 14.
The control pulses for the ink jet print head 18 are generated or initiated from a logic and drive circuit 20 through lines 22 and 24 which are supplied and connected to the ink jet print head (Fig.
1). The supply of the ink jet print head 18 with a suitable ink is brought about directly by an intermediate container 26 through a supply line 28 which connec~s with a liquid chamber of the ink jet print head. The intermediate container 26 is supplied with ink from an ink reservoir 30 by way of lines 32 and 34. The lines 28 and 34 may consist of common copper tubes while the line 32 may consist of a plastic-type hose. The ink supply from the reservoir or supply container 30 through the intermediate container 26 and to the ink jet print head 18 is effected by the suction force occurring in the print head. As will be described in more detail, this suction force occurs upon a minimum pressure condition immediately following a maximum pressure condition which causes the ejection of droplets of ink 36. The nozzle 38 of the print head 18 lies slightly over the liquid levels in the containers ~6 and 30.
In Fig. 2 there is shown a sectional representation of the ink jet print head generally designated as 18 and used in the ink jet printer shown in Fig. 1. The print head 18 is comprised of a rear portion 42 and a front portion 44, the portions 42 and 44 being preferably made of metal and plastic, respectively, and being preferably connected by means of a suitable adhesive.
In the rear portion 42 there is provided an ink chamber 46 in the form of a capillary cavity or depression as well as an ink supply channel 48 connected with the supply line 28 and leading into the ink chamber .7f~
46. Further, the portions 42 and 44 have extending therethrough a nozzle channel or passa~eway 50 which leads from the chamber 46 to a nozzle plate 52 cast in the front portion 44. The nozzle plate 52 contains the nozzle 38 which terminates the nozzle channel 50 and from which nozzle 38 the individual droplets of ink 36 are ejected to impinge on the record medium 10. As shown in Fig. 1, the ink droplet 36 ejection takes place upon energization of the drive element of the print head 18.
The drive element of the ink jet print head 18 consists of a membrane 54 which, by means of suitable adhesives, is bonded or secured to the print head rear portion 42 above and over the ink chamber 46 so that the chamber 46 is completely closed and sealed. Secured to the membrane 54 by means of suitable adhesives is a piezoelectric crystal 56. Control pulses of the voltage type are applied to the crystal 56 through terminals 22a and ~4a which are connected to respective lines 22 and 24, the line 22 being connected directly with one side of the crystal 56 whereas the line 24 may be connected to the membrane 54 itself.
Since the membrane 54 preferably consists of a conductive material, such as a metal plate, that side of the crystal 56 adjacent and connected with the membrane 54 is constantly charged with a control pulse.
In Fig. 3 the printer, as shown in Fi~. 1, is principally represented in the form of a block diagram along with and adjacent the paper 10 trained in a path past the printing station 14 and around the rollers 12 and 16, and wherein an ink supply for the ink jet print head 18 is indicated by 60 as including the main supply container 30 and the intermediate container 26. The electrical control of the ink jet print head 18 and of the membrane 54 is effected by a drive circuit 62, as shown in detail in Fig. 4, and connected with a logic circuit 64, such drive circuit 62 and logic circuit 64 being represented by the block 20 in Fig. 1. The logic circuit 64 and the drive circuit 62 are commonly supplied from a suitable voltage source 66.
In the logic circuit 64 is produced rectangular pulses 90 with a rise to a desired amplitude, and with S a required pulse width and pulse repetition sequence.
Therefore, it is essential that the rear flank or drop of each one of the rectangular pulses so produced in the logic circuit 64 be timely variable so that the length of each control pulse is adjustable. Square wave generators of the type needed in the logic circuit 64, i.e., with adjustable pulse rear flank or the time and extent thereof, are generally well-known to the person skilled in the art.
The drive circuit 62 (Fig. 4) includes a first transistor 70 with the input portion of the transistor having a resistor 72 and a capacitor 74 connected in parallel therewith. The one common or right side of the resistor 72 and of the capacitor 74 respectively is connected to the base of the transistor 70, whereas the other common or left side is connected to an input terminal 76 with a resistor 78 being connected between the base of the transistor 70 and ground. The collector of the transistor 70 is connected through a resistor 80 to a voltage terminal ~2 which has applied thereto the appropriate energy or voltage source 66. The emitter of the transistor 70 is also connected to ground. A second transistor 84 of the drive circuit has its collector directly connected to the voltage terminal 32, with the emitter thereof connected to ground through a coupling diode 86 and a resistor 88. The base of the transistor 84 is directly connected to the collector of the first transistor 70. The piezo crystal 56 is connected in parallel with the resistor 88 and is physically connected with the membrane 54 as seen in Fig. 2. The resistor 88 thus serves as a discharge resistor for the capacitively acting crystal 56.
As already stated with respect to the logic 3~
circuit 64 of Fig. 3, there is produced the rectangular pulse 90, Fig. 4, whlch is heing applied to the terminal 76, and it is through the combination of the resistor 72 and the capacitor 74 that such pulse 90 reaches the base of the transistor 70. The pulse 90 is by way of the collector o~ the transistor 70 applied to the base of the transistor 84, and such pulse directly reaches the crystal 56 by way of the emitter of the transistor 84 and the diode 86. As is generally known, upon the occurrence of a pulse at the crystal 56, there is effected the bending or deflecting of the crystal 56 and the membrane 54 connected therewith. After termination of such electrical control pulse, the crystal 56 returns to its normal position with a discharge of the capacitance o~ the crystal 56 thereby taking place through the discharge resistor 88. The discharge curve is seen at the rear flank or drop of the desired control pulse, represented as pulse 92 in Fig. 4, as well as at the rear flanks 20 or drops of the pulses 90 and 92 shown in Figs. 5A
and 5C. The curvature of the discharge curve for the desired control pulse 92 is determined by the dimensioning of or the value assigned to the discharge resistor 88.
The principle and manner of functioning of the print head 18 in accordance ~ith the present invention will now be described in greater detail with reference to Figs. 5A through 5E. ~s already stated, upon application of a control pulse to the 30 crystal 56, such crystal 56 and the membrane 54 connected therewith are caused to bend into the capillary cavity 46 of the print head 18, as shown by the dashed lines in Fig. 2. The ~irst pulse applied to the crystal 56 is represented in Fig. 5~, with the height o~ the voltage pulses at the ordinate designated by the letter U and the time course at the abscissa designated by the letter t. The pulse applied at the time instant to reaches its maximum value at the time 1~7Bl ~
tl, at which value the pulse remains until the time t3, whereupon the pulse is switched off resulting in the discharge course or drop of the pulse, as seen between t3 and t8. The pulse according to Fig. 5~ as applied to the crystal 56 causes the bending of the crystal 56 and the membrane 54 into che capillary cavity 46, which action forces the ink to flow from the capillary cavity 46 and through the passageway 50, through the no~zle plate 52 and from the nozzle 38. As shown in Fig. 5B, such actions are fluctuations of pressure in a manner which corresponds in time with the representation in Fig. 5A. Fig. 5B illustrates the time course of a pressure oscillation I in the liquid ink of the print head 18 which extends to plus and minus values about the static pressure pO with the period between each of two successive maximum pressures being designated by T and the half period being designated by T/2.
A time comparison of Fig. 5B with Fig. 5A
shows at the time instant t2 there occurs in the liquid ink of the print head 18 a maximum pressure P
which at the time instant t4 is followed by a minimum pressure PUl and whereafter there follows again a pressure increase to Po2 at the time instant t6. The pressure oscillation according to Fig. SB shows a strongly damped character. At the time instant t~
and due to the occurring maximum pressure Pol, an ink drop 36 is ejected by the nozzle 3B of the print head 18, as seen in Figs. 1 and 2. After ejection of the ink drop 36, the control pulse 90 shown in Fig. 5A is terminated at the time instant t3, releasing the pressure on the membrane 54 and thereby causing the crystal 56 and the membrane 54 to return from their tensioned position of projection ~nto the capillary cavity 46 to their flat, normal position as shown by the solid line representation thereof in Fig. 2.
The present invention is based on the knowledge that through the return or bending back of the membrane 54 out of the capillary cavity 46, there is effected an additional underpressure in the capillary cavity 46 and thus in the nozzle channel S0. At the switching-off time instant t3 of the pulse 90, as shown in Fig. 5A, the additional underpressure of the liquid as caused by the release and return to normal of the membrane 5~ reaches its maximum value at the time instant t4 as seen in Fig. 5B. Since, however, the course of the pressure oscillations I, as seen in Fig. 5B, reaches its most negative value at the same time instant t4, there occurs an addition of both minimum pressures at such time i~stant t4 which results in a characteristic minimum pressure PUl.
This excessive minimum pressure or underpressure often leads to cavitation or back pressures and to ~- 15 the gathering or sucking of air bubbles through the nozzle 38 of the print head 18, whereby the mode of functioning of the print head can be essentially disturbed or the print head can become incapable of operation. The principal object of the present invention, namely, the avoidance of such a characteristic minimum pressure PUl and a smoother operation of the print head 18, is preferably solved by use of the pulse course 92 as shown in Fig. 5C, from which the pressure course of curve II is achieved as shown in Fig. SD.
The pulse shape according to Fig. 5C differs from that according to Fig. 5A whereby the switching-off time instant of the control pulse for the piezoelectric crystal 56 takes place just at the time instant t5 rather than at time instant t3. It is in a unique manner that such course of the pulse 92 reaching the minimum pressure PU2 and occurring at the time instant t4, as seen in Fig. 5D, is not as hi~hly negative as the minimum pressure PUl shown for the pulse 90 in Fig.
5B. The course and path of the pressures for pulse 92 shown in Fiy. 5D and indicated by the height of the first negative half wave at the time instant t4 i5 - not influenced by the tension release and return to home L3L7~
movement oE the membrane 54 after the switching-off of the energizing pulse and an additional underpressure i5 reduced or lessened at such time instant t4.
At the time instant tS~ Fig. 5C, the pulse 5 92 at the crystal 56 is terminated~ It is thus seen that the underpressure is caused by or brought about through the return movement of the membrane 54 from the bending position into the cavity 46 back to its normal planar position, Fig. 2, and occurs with a delay in time of termination of the pulse, 92 the effect of which delay is advantaqeous with respect to the return to normal of membrane 54 at the time instant t6 of the pulse 90 as seen in Fig. 5B. As is evident from Fig. 5D, this delay causes the overpressure Po3 in the liquid ink of the print head 18 to be almost or substantially compensated by the lesser or reduced underpressure which is due to the tension release movement of the membrane 54. This condition is extremely advantageous, since at the time instant t4 in the waveform for pulse 92 shown in Fig. 5D there occurs an essentially lower or reduced minimum pressure PU2 than is observed in the pulse 90 waveform, according to Fig. 5B, at the time instant t4 and at the pressure PUl. The minimum pressure PU2 shown in ~ig. SD is sufficient for supplying enough liquid ink through the supply channel 48, Fig. 2, however, it is not sufficient for producing cavitation in the print head 18 or for drawing air bubbles back through the nozzle 38 into the channel 50 or into the capillary cavity 46, the absence of cavitation or air bubbles bringing about an essential increase in the reliability in operation of the print head 18.
Another advantageous development of the present invention consists in that the successive pulse which causes ejection of the next ink droplet, although not shown in Fig. 5, is timely applied so that the maximum pressure produced thereby occurs at - a delayed time of one quarter period, which may be designated as T/4 (Fig. 5D), relative to a not completely decayed maximum pressure of the preceding energization operation. It is thus evident that with succeeding pressure operations detrimental heterodyning conditions between old and new pressure oscillations are prevented.
Assuming that the first new maximum pressure would timely coincide with a not completely decayed old minimum pressure, the new maximum pressure would be reduced by the preceding residual minimum pressure whereby, due to the smaller effective maximum pressure, the ink draplet ejection speed would be decreased.
Since differences in connectian with the ink draplet ejectian speed are visible in the printing image on a record medium, these differences should be eliminated by the abave-mentioned measure in the scope of the inventian. It is ta be noted from Fig. 5D that upon a phase displacement of each new pressure oscillation by a respective quarter period (T/4) relative to the old pressure oscillation, the first maximum pressure of each new ascillatian occurs upon the passage through zero (0) af the preceding ald oscillatian sa that the new oscillation is not influenced by the preceding residual oscillàtion.
Referring back to the drawing for the ~25 purpose of rendering more clearly the operatian principle as underlying the present invention, Fig.
5E illustrates both pressure oscillations I and II
according to the curves in Figs. 5B and 5D, the oscillation II according to Fig. 5D therein being drawn heavier ar thicker than the oscillatian I according to Fig. 5B~ As is clearly apparent from Fig. 5E, at the time instant t~ through the delay of the pulse to the time instant t5, Fig. 5C, there occurs an essentially reduced or lesser minimum pressure with the value PU2 when compared with the minimum pressure PUl which occurs upon a pulse length up to the time instant t3 according to Fig. 5A. Therefore, the lowering of the underpressure from PU2 to PUl~ as previously pointed out, becomes an excessive underpressure and often results in the occurrence of cavitation and the introduction of air bubbles in the ink supply by way of the nozzle 38 of the print head 18.
The hereinabove described embodiment of the present invention defining a pulse length according to Fig. 5C represents the optimum mode of operation of the printer. It lies, however, within the scope of the inventive idea, to choose the length of the control pulse longer than it is shown in Fig. 5C. There-fore, utmost attention must be paid to the underpressure occurring after the tension release of the membrane 54 is caused to be efected, i.e., ideally occurring as long as possible prior to or as long as possible after the minimum pressure following a maximum pressure condition. In case of a very short control pulse, the underpressure as caused by the tension release of the membrane 54 will decay prior to the first minimum pressure in the liquid so that the first minimum pressure is no longer ,nfluenced by that underpressure caused by the tension release of the membrane. In another case, through the prolongation of the pulse, the minimum pressure in the liquid will already ~e exceeded to such an extent that by reason of the additional underpressure due to the tension release of the membrane 54, the underpressure does not become a dangerous minimum pressure condition. It lies therefore within the scope of the invention to set the end of the control pulse into the second period T
or even into the third or fourth period of time as shown in the several waveforms of Fig. 5. According to the principle underlying the present invention, one must always be mindful of the fact that the switching-off time instant (t) is chosen such that the underpressure occurring with delay due to the tension release of the membrane 54 does not coincide with the respective negative maximum value of the pressure oscillation in the liquid ink, that is, the minimum pressure condition.
In the embodiment of the invention as described herein, there is shown a single nozzle print head 18 for the explanation of the principle underlying the invention. Instead of such a single print head, there can also be arranged a plurality of single nozzle print heads 18 aligned across a record medium to be printed. Furthermore, it is possible to use in printers functioning according to the principle of the present invention multiple nozzle print heads instead of the single nozzle print heads and wherein the print heads may also be arranged in known manner on a carrier support element or print head carria~e which is movable in a line printing direction transverse to the transport direction of the record medium.
It is thus seen that herein shown and described is a control system for an in~ jet printer wherein the ink fluid is introduced into the print head and controlled with energy pulses which include a lessening of the underpressures or minimum pressures so as to reduce cavitation and oscillation tendencies and to thereby smooth the printing operation. The control system enables the accomplishment of the objects and advantages mentioned above, and while a preferred embodiment of the invention has been disclosed herein, variations thereof may occur to those s~illed in the art. It is contemplated that all such variations and modifications not departing from the spirit and scope of the invention hereof are to be cons~rued in accordance with the following claims.
,
INK JET PRINTER CONTROL SYSTEM
Ba~ ound of the Invention _ _ _ _ In the field of non-impact printing, the most common types of printers have been the thermal printer and the ink jet printer. When the performance of a non-impact printer is compared with that of an impact printer, one of the problems in the non-impact machine has been the control of the printing operation.
As is well-known, the impact printing operation depends upon the movement of impact members typically by reason of an electromechanical system which is believed to enable a more precise control of such impact mambers.
The advent of non-impact printing as in the case of thermal printing brought out the fact that the heating cycle must be controlled in a manner to obtain maximum repeated operations. Likewise, the control of ink jet printing must deal with rapid starting and stopping movement of the ink fluid from a supply of such fluid.
Representative prior art in the field of ink jet printing includes United States Patent No.
3,747,120 issued to N. G. E. Stemme on July 17, 1973, which discloses an arrangement of writing mechanisms or that of applying droplets of ink in liquid form to a surface and wherein a chamber is divided into an inner portion and an outer portion with a channel connecting the portions. The inner portion is provided with a piezoelectric deYice for producing short duration pressure increases in the fluid in the chamber and an intake or supply channel is connected with the outer chamber portion for transmission of the fluid through a discharqe channel.
United States Patent No. 3,946,398 issued to E. L. Xyser et al on March 23, 1976 discloses method and apparatus for recording with writing fluids and droplet projection means wherein a print head :
~7~
includes a piezoelectric crystal plate connected with a membrane and char~ed with a voltage pulse which causes the crystal plate and the membrane to bend and to produce pressure oscillations in an ink-filled liquid chamber of the print head. Upon each occurrence of a first maximum pressure in the liquid, an ink droplet is ejected through a no~zle and deposited on a record medium. In order to insure a safe release of the ink droplet at a sufficient initial speed, the crystal must be charqed with a voltage pulse of sufficient height and width to bring about a respective maximum pressure in the liquid. A minimum pressure follows the maximum pressure in the liquid chamber and the chamber is again filled with ink so that by the ~ollowing energization pulse of the crystal plate, a sufficient maximum pressure is produced which causes the next ink droplet to be ejected from the nozzle It is especially at the hi~her ~requencies that the known ink jet print heads are working quite unreliably, since there may be an excessive or high underpressure arising or developing in the liquid chamber, which excessive underpressure causes cavitation or air bubbles to come into the liquid chamber by way of the nozzle. The forming of a vacuum in the supply or flow of the ink or the presence of air bubbles in the ink leads to trouble in the exact functioning of the print head and often results in a complete Eailure of the head.
Summary of the Inventlon The present invention relates to an ink jet printer and more particularly to a control system for such printer wherein a pulse-operated and responsive membrane produces increases in the pressure oE the liquid in the ink jet print head whereupon an ink droplet is ejected with each occurrence of a maximum increase in pressure. The control system includes a B~
drive element and is arranged to minimize or eliminate excessive underpressure conditions during the operation of the membrane caused by sudden increases and decreases in the presence of the ink fluid in the print head by reason of the pulsing and termination of pulsing of the drive element.
The ink is caused to flow from an ink supply through a passageway to a chamber adjacent the membrane which chamber is spaced from the nozzle of the print head so as to provide a precise amount of ink at the origin of the pressure-increasing device and thereby better control the effects from the changing pressures. An elongated chamber or passageway is routed from the supply chamber to a nozzle plate containing the nozzle through which the droplets of ink are ejected onto the record medium.
The logic means for generating voltage pulses for the drive element or piezoelectric element which deflects or bends the membrane is conditioned whereby the membrane is maintained by the drive element in a tensioned or pulsed state for a duration of time such that the underpressure resulting from the release of the membrane timely occurs either after or prior to the minîmum pressure following the maximum pressure condition. Another way of stating the above is that the logic circuit is provided to generate drive pulses for the membrane having a time duration such that the membrane is maintained in a tensioned or pulsed state for a sufficient length of time for the pressure decrease resulting ~rom the release of the membrane to tend to compensate the pressure fluctuation in the ink resulting from the initial driving movement of the membrane.
The invention is based on the knowledge that cavitation or forming of a vacuum in the ink and the occurrence of air bubbles in the ink chamber are possible conditions for the failure of an ink jet print head due to an excessive underpressure a~ter f~
the sudden pressure increase by the pulsing device.
The underpressure half wave occurs after the overpressure half wave which effects the ejection of the ink droplet. The overpressure shall in this application be understood to be that pressure exceeding the static pressure and the underpressure shall be understood as that pressure below the static pressure.
In view of the above discussion, the principal object of the present invention is to provide an ink jet printer having an improved print head arrangement enabling smoother operation of the print head in ejecting ink droplets, and wherein the printer functions in a safer condition and where the danger of cavitation and the formation of air bubbles in the liquid chamber is reduced.
Another object of the present invention is to provide an ink jet printer wherein the supply of ink is directed into position adjacent the ink pressure increasing device for reducing excessive pressure differentials between the ink supply and the ink ; nozzle.
An additional object of the present invention is to provide a control system for an ink jet printer which applies pulse energization of the pressure-increasing device for a duration of time to effectreduction of cavitation of the ink in the ink chamber.
A further object Gf the present invention is to provide an ink jet printer with a piezoelectric driven element and a control system therefor which is effective for reducing cavitation of ink and for eliminating forma~ion of air bubb~es in the ink chamber.
Another object of the present invention is to provide a control system for an ink jet printer which maintains a tensioned state of the pressure increasing device for a duration of time to effect reduction in back pressure and to dampen or compensate pressure differentials.
- s Additional advantages and features of the present invention will become apparent and fully understood from a reading of the following description, taken together with the annexed drawing.
Brief Description of the Drawin~
Fig. 1 is a diagrammatic representation of an ink jet printer incorporating the principles of the present invention;
Fig. 2 is a sectional view of an ink jet print head for use in the printer of Fig. l;
Fig. 3 is a block diagram of the ink jet printer according to Fig. l;
Fig. 4 illustrates a drive circuit for controlling the drive element of the membrane of the ink jet print head, and Figs. 5A-5E are pulse diagrams for the explanation of the mannner of functioning of the ink jet printer according to the present invention.
Descri~tlon of the Preferred Embodiment The use of equal elements, pressure values and time instances are each provided with the same reference number in the drawing so that the principle underlying the present invention is better comprehended from the following description.
Referring to Fig. 1, there is shown a simplified diagrammatic representation of an ink jet printer which functions according to the principle underlying the present invention. A record medium or paper 10 is caused to be driven from a record medium supply roll 12 past a printing station or line of printing zone 14 to a take-up roll 16. In a suitable position adjacent the record medium 10 is arranged an ink jet print head 18 from the nozzle of which are ejected droplets of ink which are caused to impinge on the record medium 10 upon the energization of the drive element oE the ink jet print head 18. For ~1~7~
reasons of clarity in the preferred embodiment, according to the present invention as described herein, there is shown one ink jet print head 18 which is arranged in stationary manner relative to the printing station 14.
The control pulses for the ink jet print head 18 are generated or initiated from a logic and drive circuit 20 through lines 22 and 24 which are supplied and connected to the ink jet print head (Fig.
1). The supply of the ink jet print head 18 with a suitable ink is brought about directly by an intermediate container 26 through a supply line 28 which connec~s with a liquid chamber of the ink jet print head. The intermediate container 26 is supplied with ink from an ink reservoir 30 by way of lines 32 and 34. The lines 28 and 34 may consist of common copper tubes while the line 32 may consist of a plastic-type hose. The ink supply from the reservoir or supply container 30 through the intermediate container 26 and to the ink jet print head 18 is effected by the suction force occurring in the print head. As will be described in more detail, this suction force occurs upon a minimum pressure condition immediately following a maximum pressure condition which causes the ejection of droplets of ink 36. The nozzle 38 of the print head 18 lies slightly over the liquid levels in the containers ~6 and 30.
In Fig. 2 there is shown a sectional representation of the ink jet print head generally designated as 18 and used in the ink jet printer shown in Fig. 1. The print head 18 is comprised of a rear portion 42 and a front portion 44, the portions 42 and 44 being preferably made of metal and plastic, respectively, and being preferably connected by means of a suitable adhesive.
In the rear portion 42 there is provided an ink chamber 46 in the form of a capillary cavity or depression as well as an ink supply channel 48 connected with the supply line 28 and leading into the ink chamber .7f~
46. Further, the portions 42 and 44 have extending therethrough a nozzle channel or passa~eway 50 which leads from the chamber 46 to a nozzle plate 52 cast in the front portion 44. The nozzle plate 52 contains the nozzle 38 which terminates the nozzle channel 50 and from which nozzle 38 the individual droplets of ink 36 are ejected to impinge on the record medium 10. As shown in Fig. 1, the ink droplet 36 ejection takes place upon energization of the drive element of the print head 18.
The drive element of the ink jet print head 18 consists of a membrane 54 which, by means of suitable adhesives, is bonded or secured to the print head rear portion 42 above and over the ink chamber 46 so that the chamber 46 is completely closed and sealed. Secured to the membrane 54 by means of suitable adhesives is a piezoelectric crystal 56. Control pulses of the voltage type are applied to the crystal 56 through terminals 22a and ~4a which are connected to respective lines 22 and 24, the line 22 being connected directly with one side of the crystal 56 whereas the line 24 may be connected to the membrane 54 itself.
Since the membrane 54 preferably consists of a conductive material, such as a metal plate, that side of the crystal 56 adjacent and connected with the membrane 54 is constantly charged with a control pulse.
In Fig. 3 the printer, as shown in Fi~. 1, is principally represented in the form of a block diagram along with and adjacent the paper 10 trained in a path past the printing station 14 and around the rollers 12 and 16, and wherein an ink supply for the ink jet print head 18 is indicated by 60 as including the main supply container 30 and the intermediate container 26. The electrical control of the ink jet print head 18 and of the membrane 54 is effected by a drive circuit 62, as shown in detail in Fig. 4, and connected with a logic circuit 64, such drive circuit 62 and logic circuit 64 being represented by the block 20 in Fig. 1. The logic circuit 64 and the drive circuit 62 are commonly supplied from a suitable voltage source 66.
In the logic circuit 64 is produced rectangular pulses 90 with a rise to a desired amplitude, and with S a required pulse width and pulse repetition sequence.
Therefore, it is essential that the rear flank or drop of each one of the rectangular pulses so produced in the logic circuit 64 be timely variable so that the length of each control pulse is adjustable. Square wave generators of the type needed in the logic circuit 64, i.e., with adjustable pulse rear flank or the time and extent thereof, are generally well-known to the person skilled in the art.
The drive circuit 62 (Fig. 4) includes a first transistor 70 with the input portion of the transistor having a resistor 72 and a capacitor 74 connected in parallel therewith. The one common or right side of the resistor 72 and of the capacitor 74 respectively is connected to the base of the transistor 70, whereas the other common or left side is connected to an input terminal 76 with a resistor 78 being connected between the base of the transistor 70 and ground. The collector of the transistor 70 is connected through a resistor 80 to a voltage terminal ~2 which has applied thereto the appropriate energy or voltage source 66. The emitter of the transistor 70 is also connected to ground. A second transistor 84 of the drive circuit has its collector directly connected to the voltage terminal 32, with the emitter thereof connected to ground through a coupling diode 86 and a resistor 88. The base of the transistor 84 is directly connected to the collector of the first transistor 70. The piezo crystal 56 is connected in parallel with the resistor 88 and is physically connected with the membrane 54 as seen in Fig. 2. The resistor 88 thus serves as a discharge resistor for the capacitively acting crystal 56.
As already stated with respect to the logic 3~
circuit 64 of Fig. 3, there is produced the rectangular pulse 90, Fig. 4, whlch is heing applied to the terminal 76, and it is through the combination of the resistor 72 and the capacitor 74 that such pulse 90 reaches the base of the transistor 70. The pulse 90 is by way of the collector o~ the transistor 70 applied to the base of the transistor 84, and such pulse directly reaches the crystal 56 by way of the emitter of the transistor 84 and the diode 86. As is generally known, upon the occurrence of a pulse at the crystal 56, there is effected the bending or deflecting of the crystal 56 and the membrane 54 connected therewith. After termination of such electrical control pulse, the crystal 56 returns to its normal position with a discharge of the capacitance o~ the crystal 56 thereby taking place through the discharge resistor 88. The discharge curve is seen at the rear flank or drop of the desired control pulse, represented as pulse 92 in Fig. 4, as well as at the rear flanks 20 or drops of the pulses 90 and 92 shown in Figs. 5A
and 5C. The curvature of the discharge curve for the desired control pulse 92 is determined by the dimensioning of or the value assigned to the discharge resistor 88.
The principle and manner of functioning of the print head 18 in accordance ~ith the present invention will now be described in greater detail with reference to Figs. 5A through 5E. ~s already stated, upon application of a control pulse to the 30 crystal 56, such crystal 56 and the membrane 54 connected therewith are caused to bend into the capillary cavity 46 of the print head 18, as shown by the dashed lines in Fig. 2. The ~irst pulse applied to the crystal 56 is represented in Fig. 5~, with the height o~ the voltage pulses at the ordinate designated by the letter U and the time course at the abscissa designated by the letter t. The pulse applied at the time instant to reaches its maximum value at the time 1~7Bl ~
tl, at which value the pulse remains until the time t3, whereupon the pulse is switched off resulting in the discharge course or drop of the pulse, as seen between t3 and t8. The pulse according to Fig. 5~ as applied to the crystal 56 causes the bending of the crystal 56 and the membrane 54 into che capillary cavity 46, which action forces the ink to flow from the capillary cavity 46 and through the passageway 50, through the no~zle plate 52 and from the nozzle 38. As shown in Fig. 5B, such actions are fluctuations of pressure in a manner which corresponds in time with the representation in Fig. 5A. Fig. 5B illustrates the time course of a pressure oscillation I in the liquid ink of the print head 18 which extends to plus and minus values about the static pressure pO with the period between each of two successive maximum pressures being designated by T and the half period being designated by T/2.
A time comparison of Fig. 5B with Fig. 5A
shows at the time instant t2 there occurs in the liquid ink of the print head 18 a maximum pressure P
which at the time instant t4 is followed by a minimum pressure PUl and whereafter there follows again a pressure increase to Po2 at the time instant t6. The pressure oscillation according to Fig. SB shows a strongly damped character. At the time instant t~
and due to the occurring maximum pressure Pol, an ink drop 36 is ejected by the nozzle 3B of the print head 18, as seen in Figs. 1 and 2. After ejection of the ink drop 36, the control pulse 90 shown in Fig. 5A is terminated at the time instant t3, releasing the pressure on the membrane 54 and thereby causing the crystal 56 and the membrane 54 to return from their tensioned position of projection ~nto the capillary cavity 46 to their flat, normal position as shown by the solid line representation thereof in Fig. 2.
The present invention is based on the knowledge that through the return or bending back of the membrane 54 out of the capillary cavity 46, there is effected an additional underpressure in the capillary cavity 46 and thus in the nozzle channel S0. At the switching-off time instant t3 of the pulse 90, as shown in Fig. 5A, the additional underpressure of the liquid as caused by the release and return to normal of the membrane 5~ reaches its maximum value at the time instant t4 as seen in Fig. 5B. Since, however, the course of the pressure oscillations I, as seen in Fig. 5B, reaches its most negative value at the same time instant t4, there occurs an addition of both minimum pressures at such time i~stant t4 which results in a characteristic minimum pressure PUl.
This excessive minimum pressure or underpressure often leads to cavitation or back pressures and to ~- 15 the gathering or sucking of air bubbles through the nozzle 38 of the print head 18, whereby the mode of functioning of the print head can be essentially disturbed or the print head can become incapable of operation. The principal object of the present invention, namely, the avoidance of such a characteristic minimum pressure PUl and a smoother operation of the print head 18, is preferably solved by use of the pulse course 92 as shown in Fig. 5C, from which the pressure course of curve II is achieved as shown in Fig. SD.
The pulse shape according to Fig. 5C differs from that according to Fig. 5A whereby the switching-off time instant of the control pulse for the piezoelectric crystal 56 takes place just at the time instant t5 rather than at time instant t3. It is in a unique manner that such course of the pulse 92 reaching the minimum pressure PU2 and occurring at the time instant t4, as seen in Fig. 5D, is not as hi~hly negative as the minimum pressure PUl shown for the pulse 90 in Fig.
5B. The course and path of the pressures for pulse 92 shown in Fiy. 5D and indicated by the height of the first negative half wave at the time instant t4 i5 - not influenced by the tension release and return to home L3L7~
movement oE the membrane 54 after the switching-off of the energizing pulse and an additional underpressure i5 reduced or lessened at such time instant t4.
At the time instant tS~ Fig. 5C, the pulse 5 92 at the crystal 56 is terminated~ It is thus seen that the underpressure is caused by or brought about through the return movement of the membrane 54 from the bending position into the cavity 46 back to its normal planar position, Fig. 2, and occurs with a delay in time of termination of the pulse, 92 the effect of which delay is advantaqeous with respect to the return to normal of membrane 54 at the time instant t6 of the pulse 90 as seen in Fig. 5B. As is evident from Fig. 5D, this delay causes the overpressure Po3 in the liquid ink of the print head 18 to be almost or substantially compensated by the lesser or reduced underpressure which is due to the tension release movement of the membrane 54. This condition is extremely advantageous, since at the time instant t4 in the waveform for pulse 92 shown in Fig. 5D there occurs an essentially lower or reduced minimum pressure PU2 than is observed in the pulse 90 waveform, according to Fig. 5B, at the time instant t4 and at the pressure PUl. The minimum pressure PU2 shown in ~ig. SD is sufficient for supplying enough liquid ink through the supply channel 48, Fig. 2, however, it is not sufficient for producing cavitation in the print head 18 or for drawing air bubbles back through the nozzle 38 into the channel 50 or into the capillary cavity 46, the absence of cavitation or air bubbles bringing about an essential increase in the reliability in operation of the print head 18.
Another advantageous development of the present invention consists in that the successive pulse which causes ejection of the next ink droplet, although not shown in Fig. 5, is timely applied so that the maximum pressure produced thereby occurs at - a delayed time of one quarter period, which may be designated as T/4 (Fig. 5D), relative to a not completely decayed maximum pressure of the preceding energization operation. It is thus evident that with succeeding pressure operations detrimental heterodyning conditions between old and new pressure oscillations are prevented.
Assuming that the first new maximum pressure would timely coincide with a not completely decayed old minimum pressure, the new maximum pressure would be reduced by the preceding residual minimum pressure whereby, due to the smaller effective maximum pressure, the ink draplet ejection speed would be decreased.
Since differences in connectian with the ink draplet ejectian speed are visible in the printing image on a record medium, these differences should be eliminated by the abave-mentioned measure in the scope of the inventian. It is ta be noted from Fig. 5D that upon a phase displacement of each new pressure oscillation by a respective quarter period (T/4) relative to the old pressure oscillation, the first maximum pressure of each new ascillatian occurs upon the passage through zero (0) af the preceding ald oscillatian sa that the new oscillation is not influenced by the preceding residual oscillàtion.
Referring back to the drawing for the ~25 purpose of rendering more clearly the operatian principle as underlying the present invention, Fig.
5E illustrates both pressure oscillations I and II
according to the curves in Figs. 5B and 5D, the oscillation II according to Fig. 5D therein being drawn heavier ar thicker than the oscillatian I according to Fig. 5B~ As is clearly apparent from Fig. 5E, at the time instant t~ through the delay of the pulse to the time instant t5, Fig. 5C, there occurs an essentially reduced or lesser minimum pressure with the value PU2 when compared with the minimum pressure PUl which occurs upon a pulse length up to the time instant t3 according to Fig. 5A. Therefore, the lowering of the underpressure from PU2 to PUl~ as previously pointed out, becomes an excessive underpressure and often results in the occurrence of cavitation and the introduction of air bubbles in the ink supply by way of the nozzle 38 of the print head 18.
The hereinabove described embodiment of the present invention defining a pulse length according to Fig. 5C represents the optimum mode of operation of the printer. It lies, however, within the scope of the inventive idea, to choose the length of the control pulse longer than it is shown in Fig. 5C. There-fore, utmost attention must be paid to the underpressure occurring after the tension release of the membrane 54 is caused to be efected, i.e., ideally occurring as long as possible prior to or as long as possible after the minimum pressure following a maximum pressure condition. In case of a very short control pulse, the underpressure as caused by the tension release of the membrane 54 will decay prior to the first minimum pressure in the liquid so that the first minimum pressure is no longer ,nfluenced by that underpressure caused by the tension release of the membrane. In another case, through the prolongation of the pulse, the minimum pressure in the liquid will already ~e exceeded to such an extent that by reason of the additional underpressure due to the tension release of the membrane 54, the underpressure does not become a dangerous minimum pressure condition. It lies therefore within the scope of the invention to set the end of the control pulse into the second period T
or even into the third or fourth period of time as shown in the several waveforms of Fig. 5. According to the principle underlying the present invention, one must always be mindful of the fact that the switching-off time instant (t) is chosen such that the underpressure occurring with delay due to the tension release of the membrane 54 does not coincide with the respective negative maximum value of the pressure oscillation in the liquid ink, that is, the minimum pressure condition.
In the embodiment of the invention as described herein, there is shown a single nozzle print head 18 for the explanation of the principle underlying the invention. Instead of such a single print head, there can also be arranged a plurality of single nozzle print heads 18 aligned across a record medium to be printed. Furthermore, it is possible to use in printers functioning according to the principle of the present invention multiple nozzle print heads instead of the single nozzle print heads and wherein the print heads may also be arranged in known manner on a carrier support element or print head carria~e which is movable in a line printing direction transverse to the transport direction of the record medium.
It is thus seen that herein shown and described is a control system for an in~ jet printer wherein the ink fluid is introduced into the print head and controlled with energy pulses which include a lessening of the underpressures or minimum pressures so as to reduce cavitation and oscillation tendencies and to thereby smooth the printing operation. The control system enables the accomplishment of the objects and advantages mentioned above, and while a preferred embodiment of the invention has been disclosed herein, variations thereof may occur to those s~illed in the art. It is contemplated that all such variations and modifications not departing from the spirit and scope of the invention hereof are to be cons~rued in accordance with the following claims.
,
Claims (14)
1. A control system for an ink jet printer having a pulse operated membrane for producing increases in liquid pressure in a print head wherein each increase in pressure ejects an ink droplet through a nozzle in the print head, said system comprising an ink chamber occupying one side of said print head adjacent said membrane and distal from said print head nozzle, means for supplying ink into said ink chamber, a drive circuit for pulsing said membrane to cause an ink droplet to be ejected from said nozzle, and means for generating pulses to the drive circuit for maintaining the membrane in a pulsed state for a period of time such that underpressure resulting from the release of the membrane from said pulsed state occurs after the minimum pressure following the maximum pressure condition for ejecting an ink droplet.
2. The control system of claim 1 wherein the drive circuit includes a piezoelectric crystal inter-connected with said membrane.
3. The control system of claim 1 wherein the membrane is pulsed into the ink chamber for reducing the volume thereof and thereby ejecting an ink droplet from said nozzle.
4. The control system of claim 1 including means for delaying the time of release of the membrane from its pulsed state whereby the underpressure resulting therefrom coincides with a further pressure increase following the maximum pressure condition for compensation of the further increased pressure.
5. The control system of claim 1 wherein said drive circuit includes a pair of transistors and a resistive element for delaying the time of release of the membrane from its pulsed state.
6. An ink jet printer comprising a print head having an ink chamber at one end and an ink nozzle at the opposite end, a passageway connecting the ink chamber and the ink nozzle, means for supplying ink into said ink chamber, and means for causing droplets of ink to be ejected from said ink nozzle, including a membrane adjacent said ink chamber, a drive member connected with said membrane for causing said membrane to be deflected into said ink chamber, and means for generating pulses to said drive member for deflecting said membrane and thereby maximizing the pressure of said ink in said ink chamber and causing ink droplets to be ejected from said nozzle, the time of each of said pulses being maintained for a period such that underpressure resulting from the release of the membrane from its deflected position occurs after the minimum pressure following the maximum pressure condition in said ink chamber.
7. The ink jet printer of claim 6 including a nozzle plate for terminating the ink passageway and for carrying the ink nozzle.
8. The ink jet printer of claim 6 wherein said drive member comprises a piezoelectric crystal.
9. The ink jet printer of claim 6 wherein said pulse generating means includes delay of the release of the membrane from its deflected position whereby the underpressure resulting therefrom coincides with
9. The ink jet printer of claim 6 wherein said pulse generating means includes delay of the release of the membrane from its deflected position whereby the underpressure resulting therefrom coincides with
9. (concluded) a further pressure increase following the maximum pressure condition for compensation of the further increased pres-sure.
10. The ink jet printer of claim 6 wherein said pulse generating means includes a pair of transistors and a resistive element for delaying the time of release of the membrane from its deflected position.
11. The ink jet printer of claim 6 wherein successive pulses generated to said drive member are phase displaced with respect to a preceding pulse such that the first maximum pressure condition generated by each pulse occurs after the minimum pressure of the preceding oscillating period.
12. The ink jet printer of claim 11 wherein the phase displacement is one quarter of the oscillating period.
13. A method of ejecting droplets of ink from a nozzle in a print head onto a record medium comprising the steps of:
supplying a quantity of ink in the print head distal from the nozzle, pulsing the quantity of ink for a period of time by increasing the pressure thereto to cause droplets of ink to be ejected from said nozzle, and maintaining the pulse time of increased pressure in an amount such that underpressure resulting from ceasing the pulsing occurs after a minimum pressure following the maximum increased pressure condition.
14. The method of claim 13 wherein the pulsing is maintained for a period of time in a
supplying a quantity of ink in the print head distal from the nozzle, pulsing the quantity of ink for a period of time by increasing the pressure thereto to cause droplets of ink to be ejected from said nozzle, and maintaining the pulse time of increased pressure in an amount such that underpressure resulting from ceasing the pulsing occurs after a minimum pressure following the maximum increased pressure condition.
14. The method of claim 13 wherein the pulsing is maintained for a period of time in a
14. (concluded) manner wherein successive cycles are displaced in relation to each other so that the initial pressure increase generated by a pulse is later than the pressure decrease of a preceding cycle.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19782808407 DE2808407C2 (en) | 1978-02-27 | 1978-02-27 | Control device for an ink droplet printing device |
| DEP2808407.3 | 1978-02-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1117815A true CA1117815A (en) | 1982-02-09 |
Family
ID=6033067
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000322267A Expired CA1117815A (en) | 1978-02-27 | 1979-02-26 | Ink jet printer control system |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS54123951A (en) |
| CA (1) | CA1117815A (en) |
| DE (1) | DE2808407C2 (en) |
| FR (1) | FR2418089A1 (en) |
| GB (1) | GB2014910B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56161172A (en) * | 1980-05-15 | 1981-12-11 | Sanyo Electric Co Ltd | Ink jet printer |
| JPS572766A (en) * | 1980-06-09 | 1982-01-08 | Nec Corp | Ink jet recorder |
| JPS6222371Y2 (en) * | 1980-11-20 | 1987-06-06 | ||
| AT372651B (en) * | 1980-12-15 | 1983-11-10 | Philips Nv | INK-JET PRINT HEAD AND METHOD FOR PRODUCING SUCH INK-JET PRINT HEAD |
| DE3247540A1 (en) * | 1981-12-26 | 1983-07-07 | Konishiroku Photo Industry Co., Ltd., Tokyo | INK PENS |
| DE3504011A1 (en) * | 1985-02-06 | 1986-08-07 | Siemens AG, 1000 Berlin und 8000 München | Making contact with oscillating components by means of conductive rubber |
| JP3237685B2 (en) * | 1992-11-05 | 2001-12-10 | セイコーエプソン株式会社 | Ink jet recording device |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3946398A (en) * | 1970-06-29 | 1976-03-23 | Silonics, Inc. | Method and apparatus for recording with writing fluids and drop projection means therefor |
| GB1350836A (en) * | 1970-06-29 | 1974-04-24 | Kyser E L | Method and apparatus for recording with writing fluids and drop projection means therefor |
| US3683212A (en) * | 1970-09-09 | 1972-08-08 | Clevite Corp | Pulsed droplet ejecting system |
| SE349676B (en) * | 1971-01-11 | 1972-10-02 | N Stemme | |
| US3893131A (en) * | 1973-09-04 | 1975-07-01 | Xerox Corp | Ink printer |
| DE2548691C3 (en) * | 1975-10-30 | 1986-04-17 | Siemens AG, 1000 Berlin und 8000 München | Circuit arrangement for controlling writing nozzles in ink mosaic writing devices |
| CA1084098A (en) * | 1975-11-21 | 1980-08-19 | Richard H. Vernon | Meniscus dampening drop generator |
| US4126867A (en) * | 1977-08-29 | 1978-11-21 | Silonics, Inc. | Ink jet printer driving circuit |
-
1978
- 1978-02-27 DE DE19782808407 patent/DE2808407C2/en not_active Expired
-
1979
- 1979-02-20 GB GB7905963A patent/GB2014910B/en not_active Expired
- 1979-02-26 JP JP2089279A patent/JPS54123951A/en active Pending
- 1979-02-26 CA CA000322267A patent/CA1117815A/en not_active Expired
- 1979-02-27 FR FR7904934A patent/FR2418089A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| DE2808407C2 (en) | 1983-06-30 |
| FR2418089A1 (en) | 1979-09-21 |
| FR2418089B1 (en) | 1984-01-27 |
| GB2014910B (en) | 1982-04-07 |
| DE2808407A1 (en) | 1979-08-30 |
| GB2014910A (en) | 1979-09-05 |
| JPS54123951A (en) | 1979-09-26 |
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