CA2079419A1 - Drop quality control system for jet printing - Google Patents
Drop quality control system for jet printingInfo
- Publication number
- CA2079419A1 CA2079419A1 CA002079419A CA2079419A CA2079419A1 CA 2079419 A1 CA2079419 A1 CA 2079419A1 CA 002079419 A CA002079419 A CA 002079419A CA 2079419 A CA2079419 A CA 2079419A CA 2079419 A1 CA2079419 A1 CA 2079419A1
- Authority
- CA
- Canada
- Prior art keywords
- ink
- velocity
- reservoir
- fresh
- nozzle
- 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.)
- Abandoned
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
- B41J2/07—Ink jet characterised by jet control
- B41J2/115—Ink jet characterised by jet control synchronising the droplet separation and charging time
-
- 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
- B41J2/17—Ink jet characterised by ink handling
- B41J2/18—Ink recirculation systems
-
- 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
- B41J2/17—Ink jet characterised by ink handling
- B41J2/195—Ink jet characterised by ink handling for monitoring ink quality
Abstract
ABSTRACT OF THE DISCLOSURE
A method and apparatus are disclosed for controlling the flight time and composition of a marking fluid used in a continuous jet marking system. A three-way valve permits switching between fresh ink and system ink supplies.
Periodically a comparison of pressure required to maintain a constant drop flight time is made by a controller. Because both supplies are in the same operating environment any difference in pressure is due to a change in system ink viscosity. Make up solvent is added, if necessary, via a pump to restore viscosity to desired values.
A method and apparatus are disclosed for controlling the flight time and composition of a marking fluid used in a continuous jet marking system. A three-way valve permits switching between fresh ink and system ink supplies.
Periodically a comparison of pressure required to maintain a constant drop flight time is made by a controller. Because both supplies are in the same operating environment any difference in pressure is due to a change in system ink viscosity. Make up solvent is added, if necessary, via a pump to restore viscosity to desired values.
Description
2~794~9 PATENT
DOCRET NO. 2116 DROP QUALITY CONTROL SYSTEM FOR æT PRI~TING
8ACRGR(:)UND QF THE INVEN~ION
This invention relates to the field of drop marking ystems of the type in which a marking fluid is forced through a nozzle, which converts the liquid into droplets which can then be controlled by various means while pro~ected toward a ~ubstrate for marking purposes. Examples of such systems include the familiar ink ~et marking systems used for high speed label printing, product identification and the like, although there are other drop marking systems known in the art.
One particular type of system which advantageously employs the pre~ent invention is the continuous stream, synchronous ink ~et printer. Such a ~ystem typically includes an ink reser~oir and a remotely located nozzle or printhead connected to the reservoir by a conduit. Ink is forced under pressure from the reservoir to the nozzle which emits a continuous stream of ink drops. The ink, which is electrically conductive, is provided with a charge as the drops leave the nozzle. The drops then pass through a deflection field which causes selected drops to be deflected 80 that some of the drops are deposited onto a substrate while the remaining drops are returned to the reservoir for reuse.
2o79~l9 It is known in the prior art to sense the flow of the ink from the reservoir and adjust ink parameters to maintain a desired flow rate. This teaching is found in the present assignee~s prior U.S. Patent No. 4,555,712. In the '712 patent a method and apparatus are disclosed which provide a means for determining and maintaining ink drop velocity substantially constant in a manner which is substantially more accurate than was obtainable in the prior art.
In a preferred embodiment of the ~712 patent the control system ad~usts the flow rate by controlling the addition of make-up solvent to the ink reservoir. The viscosity of the ink is thereby ad~usted so a~ to maintain drop velocity substantially constant.
Experience with this syst~m ha~ demonstrated that wide variations in temperature may cause the percentage of solids (dyes and resins) in the ink supply to vary by as much as ten to forty percent from its initial composition while maintaining viscosity and flow rate substantially constant. Such a wide ~hift in composition affects other characteristics important in an ink ~et ~ystem, such as ink drying time, drop break off point and even the charging characteristics of the ink drops.
An improvement over the system disclosed in the ~712 patent is de~cribed in United State~ P~tent No. 4,860,027. The '027 . _ ., patent teaches a method of compensating for temperature variations so that the marking fluid composition is maintained within acceptable ranges. This is accomplished by measuring temperature changes at selected intervals and determining the flow time differences due to such temperature change. This information is used to alter the referenced 10w time employed by the electronic controller in deciding whethcr to add additional solvent to the marking fluid.
The '027 patent, although accounting for temperature variation to maintain composition within acceptable levels, does not maintain flow time constant under some operating conditions.
Specifically, it ad~usts the flow time to compensate for perceived changes in operating temperature thereby altering flight time. In some circumstances, this i5 undesirable, as.
flight time is also critical to print quality.
It is accordingly an ob~ect of the present invention to maintain drop flight time relatively constant while ~till accounting for temperature variations and changes in the marking fluid composition during extended operation.
SUMMARY OF THE INVENTION
According to the present invention, ink drop velocity and, therefore, drop flight time is maintained substantially constant.
:
This is accomplished by employing a drop velocity detector which causes the controller to adjust flow pressure as necessary.
System ink supply is altered by the addition of solvent when required.
A three-way valve is employed so that either fresh ink (ink which has not been cycled through the system) or system ink can be provided to the inX ~et nozzle. During set up, fresh ink is supplied and the velocity of the drops e~ected from the nozzle is set to the desired velocity for optimal printing results.
After printing operations have commenced using system ink, the controller periodically operates the three-way valve to again employ fresh ink. The system is readjusted to maintain drop velocity constant under current operating conditions, thereby to account for any change~ in temperature, noz~le wear and myriad other system variations. The pressure sensor in the fluid line detects fluid pressure. This reading is then stored for comparison.
The valve is then switched back to the system ink ~upply.
Drop velocity for the ~y~tem ink is brought up to the desired value and a reading from the pressure sensor is compared with the value obtained for the fresh ink ~upply. Because the velocity and operation temperature is the ~ame in both cases, only changes in viscosity of the system Lnk are reflected in any detected 20794~9 differences in pressure readings. If ~olvent i5 required to adjust viscosity, it is added by means of a solvent pump from a solvent reservoir.
B~IEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a preferred embodlment of the lnvention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
As indicated in the background portion of the specification, the present invention is an improvement upon prior U.S. Patent Nos. 4,S55,712 and 4,860,027 both of which are hereby incorporated by reference. In these patents it is taught to maintain flow rate of inX from a reservoir to a nozzle relatively constant. In turn, this maintains drop velocity of the drop~
emLtted from the nozzle relatively constant optimizing the quality of the printing accomplished by the device. ~he '712 patent discloses that flow rate can be maintained constant in a number of ways including ad~usting the pressure used to move the lnk from the reservoir to the nozzle; adding ~olvent to alter the viscosity composition of the ink; as well as heating or cooling the ink.
In general, the preferred way of maintaining constant flow rate or flight time is to add "makeup solvent to the ink supply.
This is because ink drops which are not used for marking are returned to the system ink supply for reuse. The solvent component of the ink is volatile and over time evaporation result~ in a viscosity increase. Other operating conditions often ma~k this change in viscosity making it difficult to know when and how much solvent to add. For example, temperature increases as the equipment heats up during prolonged use can interfere with systems which simply maintain viscosity constant.
The '027 patent attempted to solve this problem by incorporating a temperature sensor adjacent the nozzle for providing an ad~u~tment to the flow time calculation which would compensate for temperature changes. Although reasonably successful, it i8 possible to maintain flow rate tand flight time) con~tant while automatically compensating for temperature according to th~ pre~ent invention without monitoring temperature nor ad~usting control parameter~ as a function of temperature.
Furthermore, the present invention maintains the integrity of the ink compo~ition better than the prior art because it employs a dynamic comparison of the flow rate and viscosity of the ~y~tem ink with the flow rate and viscosity of fresh ink under the identical operating conditions. In this way, look-up tables, ink compensation data, temperature correction factors and the like are eliminated along with the unreliability which necessarily occurs due to real world differences between, for example, the written specifications of a particular ink and the actual characteristics of the shipment being used.
Referring to the Figure, a preferred embodiment of an apparatus for carrying out the invention is illustrated. A
printhead 10 includes a nozzle 12 which receives a supply of inX
via a three-way valve 14 from a system ink reservoir 16. Ink supplied to the nozzle is formed into a stream of droplets by energy supplied by a piezoelectric device as known in the art.
The drops pass a charging electrode 18 where selected drops are electrically charged and ~hen through a high voltage deflection field 20. Drops which have been charged are deflected to a substrate to be marked while uncharged drops are returned to the system ink reservoir 16 via collector 22.
The velocity of the drops in ~light is measured by a drop velocity detector 24 associated with the high voltage deflection plates 20. The drop velocity detector is conventional as, for example, of the type described in United States Patent No.
4,417,256 to Filmore.
Disposed in the ~upply llne from the system inX supply 16 to the nozzle 12 is a pressure sensor 26 from which viscosity changes can be determined. The output from the pressure sensor 26 and the drop velocity detector 24 are supplied to a controller 28 of the type described in the ~712 and ~077 patents. This controller may be a solid state logic system or a programmed micro-computer system. In either case, its function is to properly operate the printing system. It receives input~ from the pressure sensor and the drop velocity detector and operates a three-way valve 14 and a pre~sure Rource 30 I-sed to deliver system ink from the reservoir to the nozzle.
Pressure source 30, in the illustrated embodiment, i~ a source of compressed air. If desired, a fluid pump can be used in place of pressure source 30.
When the sy3tem ink supply requires the addition of solvent, a pump 32 add~ it to the reservoir 16 from a solvent supply 34.
Operation of this pump is under control of the controller 28.
For the purposes to be described hereafter, a fresh ink reservoir 36 is provided and is pressurized in the same way as system ink reservoir 16. The process controller 28, by operating a three-way valve 14, can substitute fre~h ink for syqtem ink when it i8 de~ired to check system operation. Note, that unuqed fre~h ink is returned to the system ink reservoir 16 not the fresh ink reservoir 36. Thus, the freqh ink reservoir contain~
only virgin ink from which no evaporation of solvent has taken place.
2079~9 According to the present invention, the fresh ink reservoir is maintained in ~ubstantially the same operating environment as the system ink reservoir. Thus, it will be sub~ect to the same temperature, vibration and other environmental conditions. This is an important aspect of the present invention for it ensures that when a comparison of fresh ink versus system ink is made, as will be described hereafter, any differences detected are due almost exclusively to changes in the system ink composition and not to temperature or other variables. In this way, the need for a temperature sensor and temperature compensation of the viscosity calculations of the type disclosed in the ~021 patent are eliminated.
Operation of the system according to the present invention is as follows. Initially, the pressure source 30 is ad~usted using fresh ink so that the velocity of drops emitted from nozzle 12 are within predetermined limits which produce the best printing for a given substrate, distance, etc.
Printing i8 then initiated using ink from the sy~tem ink reservoir supplied to the nozzle via the valve 14.
Periodically, it is important to determine the present quality of the system ink. For this purpose, the processor operates valve 14 and switches to the fresh ink reservoir 36.
_ 9 _ The system is then adjusted un~il the drop velocity detector 24 indicates that drop velocity is within the desired limits established at the initial set up. At that tLme, the pressure sensor 26 is also interrogated to determine the pressure neces~ary to produce the desired drop velocity. This preYsure value is compared with the value recorded during normal operation of the printhead using ink from the system ink reservoir 16.
Because velocity is the same and ~ecause both ink reservoirs are at substantially the same temperature, any pressure difference between the fresh ink and the system ink reflects a change in viscosity of the system ink from its initial value.
Compensation can then be made by adding solvent, if necessary, from reservoir 34 using pump 32.
If the pressure required for the system ink, P. is greater than the pressure required for fresh ink, Pr than the ~ystem ink i~ more viscous than the fresh ink. If the rever~e is true, due to for example, temperature changes in the system durLng prolonged operation or other causes, than the addition of solvent i8 withheld. Stated mathematically, the pressure difference Pd is equal to:
Pd P~ P~
lf the dlfference is positive, solvent is added, if negative, 2079~19 solvent is withheld.
The present invention, because it eliminates temperature variation and drop velocity variation to focus solely on changes in viscosity can produce results not obtainabla in the prior art.
Furthermore, because the comparison is made between ink that has been used and fresh ink from the same batch or lot, it i3 possible to customize the ink composition by holding Pd at a constant value other than zero. For example, if it were de~ired to maintain ink viscosity greater than fresh ink, it is only necessary to instruct the controller to maintain Pd at a desired value greater than zero (constant offset). Alternatively, if Pd is held negative, the system ink viscosity is maintained lower than the viscosity of the fresh inX. ~his constant offset capability be advantageously used to customize ink characteristics for different printers and printing applications.
While preferred embodiments of the present invention have been illustrated and described, it will be under~tood by those of ordinary skill in the art that changes and modifications can be made without departing from the invention in its broader aspects.
Various features of the present invention are set forth in the following claims.
DOCRET NO. 2116 DROP QUALITY CONTROL SYSTEM FOR æT PRI~TING
8ACRGR(:)UND QF THE INVEN~ION
This invention relates to the field of drop marking ystems of the type in which a marking fluid is forced through a nozzle, which converts the liquid into droplets which can then be controlled by various means while pro~ected toward a ~ubstrate for marking purposes. Examples of such systems include the familiar ink ~et marking systems used for high speed label printing, product identification and the like, although there are other drop marking systems known in the art.
One particular type of system which advantageously employs the pre~ent invention is the continuous stream, synchronous ink ~et printer. Such a ~ystem typically includes an ink reser~oir and a remotely located nozzle or printhead connected to the reservoir by a conduit. Ink is forced under pressure from the reservoir to the nozzle which emits a continuous stream of ink drops. The ink, which is electrically conductive, is provided with a charge as the drops leave the nozzle. The drops then pass through a deflection field which causes selected drops to be deflected 80 that some of the drops are deposited onto a substrate while the remaining drops are returned to the reservoir for reuse.
2o79~l9 It is known in the prior art to sense the flow of the ink from the reservoir and adjust ink parameters to maintain a desired flow rate. This teaching is found in the present assignee~s prior U.S. Patent No. 4,555,712. In the '712 patent a method and apparatus are disclosed which provide a means for determining and maintaining ink drop velocity substantially constant in a manner which is substantially more accurate than was obtainable in the prior art.
In a preferred embodiment of the ~712 patent the control system ad~usts the flow rate by controlling the addition of make-up solvent to the ink reservoir. The viscosity of the ink is thereby ad~usted so a~ to maintain drop velocity substantially constant.
Experience with this syst~m ha~ demonstrated that wide variations in temperature may cause the percentage of solids (dyes and resins) in the ink supply to vary by as much as ten to forty percent from its initial composition while maintaining viscosity and flow rate substantially constant. Such a wide ~hift in composition affects other characteristics important in an ink ~et ~ystem, such as ink drying time, drop break off point and even the charging characteristics of the ink drops.
An improvement over the system disclosed in the ~712 patent is de~cribed in United State~ P~tent No. 4,860,027. The '027 . _ ., patent teaches a method of compensating for temperature variations so that the marking fluid composition is maintained within acceptable ranges. This is accomplished by measuring temperature changes at selected intervals and determining the flow time differences due to such temperature change. This information is used to alter the referenced 10w time employed by the electronic controller in deciding whethcr to add additional solvent to the marking fluid.
The '027 patent, although accounting for temperature variation to maintain composition within acceptable levels, does not maintain flow time constant under some operating conditions.
Specifically, it ad~usts the flow time to compensate for perceived changes in operating temperature thereby altering flight time. In some circumstances, this i5 undesirable, as.
flight time is also critical to print quality.
It is accordingly an ob~ect of the present invention to maintain drop flight time relatively constant while ~till accounting for temperature variations and changes in the marking fluid composition during extended operation.
SUMMARY OF THE INVENTION
According to the present invention, ink drop velocity and, therefore, drop flight time is maintained substantially constant.
:
This is accomplished by employing a drop velocity detector which causes the controller to adjust flow pressure as necessary.
System ink supply is altered by the addition of solvent when required.
A three-way valve is employed so that either fresh ink (ink which has not been cycled through the system) or system ink can be provided to the inX ~et nozzle. During set up, fresh ink is supplied and the velocity of the drops e~ected from the nozzle is set to the desired velocity for optimal printing results.
After printing operations have commenced using system ink, the controller periodically operates the three-way valve to again employ fresh ink. The system is readjusted to maintain drop velocity constant under current operating conditions, thereby to account for any change~ in temperature, noz~le wear and myriad other system variations. The pressure sensor in the fluid line detects fluid pressure. This reading is then stored for comparison.
The valve is then switched back to the system ink ~upply.
Drop velocity for the ~y~tem ink is brought up to the desired value and a reading from the pressure sensor is compared with the value obtained for the fresh ink ~upply. Because the velocity and operation temperature is the ~ame in both cases, only changes in viscosity of the system Lnk are reflected in any detected 20794~9 differences in pressure readings. If ~olvent i5 required to adjust viscosity, it is added by means of a solvent pump from a solvent reservoir.
B~IEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a preferred embodlment of the lnvention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
As indicated in the background portion of the specification, the present invention is an improvement upon prior U.S. Patent Nos. 4,S55,712 and 4,860,027 both of which are hereby incorporated by reference. In these patents it is taught to maintain flow rate of inX from a reservoir to a nozzle relatively constant. In turn, this maintains drop velocity of the drop~
emLtted from the nozzle relatively constant optimizing the quality of the printing accomplished by the device. ~he '712 patent discloses that flow rate can be maintained constant in a number of ways including ad~usting the pressure used to move the lnk from the reservoir to the nozzle; adding ~olvent to alter the viscosity composition of the ink; as well as heating or cooling the ink.
In general, the preferred way of maintaining constant flow rate or flight time is to add "makeup solvent to the ink supply.
This is because ink drops which are not used for marking are returned to the system ink supply for reuse. The solvent component of the ink is volatile and over time evaporation result~ in a viscosity increase. Other operating conditions often ma~k this change in viscosity making it difficult to know when and how much solvent to add. For example, temperature increases as the equipment heats up during prolonged use can interfere with systems which simply maintain viscosity constant.
The '027 patent attempted to solve this problem by incorporating a temperature sensor adjacent the nozzle for providing an ad~u~tment to the flow time calculation which would compensate for temperature changes. Although reasonably successful, it i8 possible to maintain flow rate tand flight time) con~tant while automatically compensating for temperature according to th~ pre~ent invention without monitoring temperature nor ad~usting control parameter~ as a function of temperature.
Furthermore, the present invention maintains the integrity of the ink compo~ition better than the prior art because it employs a dynamic comparison of the flow rate and viscosity of the ~y~tem ink with the flow rate and viscosity of fresh ink under the identical operating conditions. In this way, look-up tables, ink compensation data, temperature correction factors and the like are eliminated along with the unreliability which necessarily occurs due to real world differences between, for example, the written specifications of a particular ink and the actual characteristics of the shipment being used.
Referring to the Figure, a preferred embodiment of an apparatus for carrying out the invention is illustrated. A
printhead 10 includes a nozzle 12 which receives a supply of inX
via a three-way valve 14 from a system ink reservoir 16. Ink supplied to the nozzle is formed into a stream of droplets by energy supplied by a piezoelectric device as known in the art.
The drops pass a charging electrode 18 where selected drops are electrically charged and ~hen through a high voltage deflection field 20. Drops which have been charged are deflected to a substrate to be marked while uncharged drops are returned to the system ink reservoir 16 via collector 22.
The velocity of the drops in ~light is measured by a drop velocity detector 24 associated with the high voltage deflection plates 20. The drop velocity detector is conventional as, for example, of the type described in United States Patent No.
4,417,256 to Filmore.
Disposed in the ~upply llne from the system inX supply 16 to the nozzle 12 is a pressure sensor 26 from which viscosity changes can be determined. The output from the pressure sensor 26 and the drop velocity detector 24 are supplied to a controller 28 of the type described in the ~712 and ~077 patents. This controller may be a solid state logic system or a programmed micro-computer system. In either case, its function is to properly operate the printing system. It receives input~ from the pressure sensor and the drop velocity detector and operates a three-way valve 14 and a pre~sure Rource 30 I-sed to deliver system ink from the reservoir to the nozzle.
Pressure source 30, in the illustrated embodiment, i~ a source of compressed air. If desired, a fluid pump can be used in place of pressure source 30.
When the sy3tem ink supply requires the addition of solvent, a pump 32 add~ it to the reservoir 16 from a solvent supply 34.
Operation of this pump is under control of the controller 28.
For the purposes to be described hereafter, a fresh ink reservoir 36 is provided and is pressurized in the same way as system ink reservoir 16. The process controller 28, by operating a three-way valve 14, can substitute fre~h ink for syqtem ink when it i8 de~ired to check system operation. Note, that unuqed fre~h ink is returned to the system ink reservoir 16 not the fresh ink reservoir 36. Thus, the freqh ink reservoir contain~
only virgin ink from which no evaporation of solvent has taken place.
2079~9 According to the present invention, the fresh ink reservoir is maintained in ~ubstantially the same operating environment as the system ink reservoir. Thus, it will be sub~ect to the same temperature, vibration and other environmental conditions. This is an important aspect of the present invention for it ensures that when a comparison of fresh ink versus system ink is made, as will be described hereafter, any differences detected are due almost exclusively to changes in the system ink composition and not to temperature or other variables. In this way, the need for a temperature sensor and temperature compensation of the viscosity calculations of the type disclosed in the ~021 patent are eliminated.
Operation of the system according to the present invention is as follows. Initially, the pressure source 30 is ad~usted using fresh ink so that the velocity of drops emitted from nozzle 12 are within predetermined limits which produce the best printing for a given substrate, distance, etc.
Printing i8 then initiated using ink from the sy~tem ink reservoir supplied to the nozzle via the valve 14.
Periodically, it is important to determine the present quality of the system ink. For this purpose, the processor operates valve 14 and switches to the fresh ink reservoir 36.
_ 9 _ The system is then adjusted un~il the drop velocity detector 24 indicates that drop velocity is within the desired limits established at the initial set up. At that tLme, the pressure sensor 26 is also interrogated to determine the pressure neces~ary to produce the desired drop velocity. This preYsure value is compared with the value recorded during normal operation of the printhead using ink from the system ink reservoir 16.
Because velocity is the same and ~ecause both ink reservoirs are at substantially the same temperature, any pressure difference between the fresh ink and the system ink reflects a change in viscosity of the system ink from its initial value.
Compensation can then be made by adding solvent, if necessary, from reservoir 34 using pump 32.
If the pressure required for the system ink, P. is greater than the pressure required for fresh ink, Pr than the ~ystem ink i~ more viscous than the fresh ink. If the rever~e is true, due to for example, temperature changes in the system durLng prolonged operation or other causes, than the addition of solvent i8 withheld. Stated mathematically, the pressure difference Pd is equal to:
Pd P~ P~
lf the dlfference is positive, solvent is added, if negative, 2079~19 solvent is withheld.
The present invention, because it eliminates temperature variation and drop velocity variation to focus solely on changes in viscosity can produce results not obtainabla in the prior art.
Furthermore, because the comparison is made between ink that has been used and fresh ink from the same batch or lot, it i3 possible to customize the ink composition by holding Pd at a constant value other than zero. For example, if it were de~ired to maintain ink viscosity greater than fresh ink, it is only necessary to instruct the controller to maintain Pd at a desired value greater than zero (constant offset). Alternatively, if Pd is held negative, the system ink viscosity is maintained lower than the viscosity of the fresh inX. ~his constant offset capability be advantageously used to customize ink characteristics for different printers and printing applications.
While preferred embodiments of the present invention have been illustrated and described, it will be under~tood by those of ordinary skill in the art that changes and modifications can be made without departing from the invention in its broader aspects.
Various features of the present invention are set forth in the following claims.
Claims (11)
1. A method of regulating ink viscosity while maintaining desired ink drop velocity in a drop marking device, comprising the steps of:
a. setting the desired drop velocity using only fresh ink;
b. thereafter operating the marking device using ink which is recycled through the marking device and subject to solvent evaporation and temperature variations;
c. determining the fluid pressure, P?,required to maintain the desired drop velocity while using the recycled ink;
d. periodically reverting to the use of fresh ink which is subjected to the same temperature variations as the recycled ink;
e. restoring the drop velocity to the desired value during step d operation;
f. determining the fluid pressure, P?, required to produce the desired drop velocity during step d operation;
g. determining the pressure difference, Pd, where Pd=Pa-Pf;
h. adding solvent to the recycled ink if Pd is greater than desired.
a. setting the desired drop velocity using only fresh ink;
b. thereafter operating the marking device using ink which is recycled through the marking device and subject to solvent evaporation and temperature variations;
c. determining the fluid pressure, P?,required to maintain the desired drop velocity while using the recycled ink;
d. periodically reverting to the use of fresh ink which is subjected to the same temperature variations as the recycled ink;
e. restoring the drop velocity to the desired value during step d operation;
f. determining the fluid pressure, P?, required to produce the desired drop velocity during step d operation;
g. determining the pressure difference, Pd, where Pd=Pa-Pf;
h. adding solvent to the recycled ink if Pd is greater than desired.
2. A method of detecting non temperature related changes in ink viscosity while maintaining a desired ink drop velocity in a drop marking device, comprising the steps of:
a. setting the desired drop velocity using only fresh ink;
b. thereafter operating the marking device using ink which is recycled through the marking device and subject to solvent evaporation and temperature variations;
c. determining the fluid pressure, Pa, required to maintain the desired drop velocity while using the recycled ink;
d. periodically reverting to the use of fresh ink which is subjected to the same temperature variations as the recycled ink;
e. restoring the drop velocity to the desired value during step d operation;
f. determining the fluid pressure, P?, required to produce the desired drop velocity during step d operation;
g. determining the pressure difference, Pd, where Pd=Pa-Pf, said difference corresponding to the change in ink viscosity due to factors other than temperature variation.
a. setting the desired drop velocity using only fresh ink;
b. thereafter operating the marking device using ink which is recycled through the marking device and subject to solvent evaporation and temperature variations;
c. determining the fluid pressure, Pa, required to maintain the desired drop velocity while using the recycled ink;
d. periodically reverting to the use of fresh ink which is subjected to the same temperature variations as the recycled ink;
e. restoring the drop velocity to the desired value during step d operation;
f. determining the fluid pressure, P?, required to produce the desired drop velocity during step d operation;
g. determining the pressure difference, Pd, where Pd=Pa-Pf, said difference corresponding to the change in ink viscosity due to factors other than temperature variation.
3. Apparatus for detecting non temperature related changes in ink viscosity in a drop marking device in which an ink stream is forced through a nozzle at a selected velocity by a pressure source to create marking drops comprising:
a) means for detecting ink velocity;
b) means for detecting the fluid pressure of the ink supplied to the nozzle;
c) a first reservoir initially containing fresh ink which is repeatedly cycled through the marking device and returned to such first reservoir and therefore subject to solvent evaporation and temperature variation;
d) a second reservoir containing only fresh ink subject only to temperature variation;
e) means for switching between said first and second reservoirs for supplying ink to the nozzle;
f) means responsive to said velocity detecting means and said pressure detecting means, for periodically calculating:
i) the fluid pressure Pa required to maintain said selected ink velocity while using cycled ink from said first reservoir;
ii) the fluid pressure Pf required to maintain such a selected ink velocity while using fresh ink from said second reservoir;
iii) the pressure difference Pd=Pa-Pf, said difference corresponding to the change in ink viscosity due to factors other than temperature variation;
g) said means for periodically calculating including means for operating said switch means to permit periodic detection of the ink velocity and fluid pressure for ink from each of said first and second reservoirs.
a) means for detecting ink velocity;
b) means for detecting the fluid pressure of the ink supplied to the nozzle;
c) a first reservoir initially containing fresh ink which is repeatedly cycled through the marking device and returned to such first reservoir and therefore subject to solvent evaporation and temperature variation;
d) a second reservoir containing only fresh ink subject only to temperature variation;
e) means for switching between said first and second reservoirs for supplying ink to the nozzle;
f) means responsive to said velocity detecting means and said pressure detecting means, for periodically calculating:
i) the fluid pressure Pa required to maintain said selected ink velocity while using cycled ink from said first reservoir;
ii) the fluid pressure Pf required to maintain such a selected ink velocity while using fresh ink from said second reservoir;
iii) the pressure difference Pd=Pa-Pf, said difference corresponding to the change in ink viscosity due to factors other than temperature variation;
g) said means for periodically calculating including means for operating said switch means to permit periodic detection of the ink velocity and fluid pressure for ink from each of said first and second reservoirs.
4. The apparatus of Claim 3 further including:
means for adding solvent to said first reservoir, said means for periodically calculating causing operation of said solvent adding means if Pd is greater than zero ? a constant.
means for adding solvent to said first reservoir, said means for periodically calculating causing operation of said solvent adding means if Pd is greater than zero ? a constant.
5. The apparatus of Claim 3 wherein the means for detecting ink velocity is a drop velocity detector.
6. The apparatus of Claim 3 wherein the means for detecting fluid pressure is a pressure sensor in circuit with the ink supply to said nozzle.
7. The apparatus of Claim 3 wherein the ink in forced through the nozzle by a pressure source applied to said first and second reservoirs.
8. The apparatus of Claim 3 wherein the means for switching between the first and second reservoirs includes a three-way valve, the inputs to the valve connected to each of the reservoirs and the output being supplied to said nozzle.
9. The apparatus of Claim 3 wherein said means for periodically calculating is a microprocessor based programmable controller.
10. The apparatus of Claim 4 wherein the means for adding solvent includes:
a) a solvent reservoir; and b) a means for injecting solvent into said first reservoir.
a) a solvent reservoir; and b) a means for injecting solvent into said first reservoir.
11. An apparatus for maintaining the viscosity of ink delivered from a system ink supply to a nozzle to produce droplets comprising in combination:
a supply of fresh ink which is located in proximity to, but segregated from the system ink supply for exposure to common temperature conditions:
means selectively operable for delivering ink from either the system ink supply or said fresh ink supply to the nozzle to produce droplets;
means for sensing the velocity of the droplets means for sensing a first pressure applied to ink delivered from said fresh ink supply to produce having a predetermined velocity and a second pressure applied to ink delivered from said system ink supply to produce droplets having said same predetermined velocity; and means responsive to a difference between said first and second pressures to mix a selected quantity of additive with the ink in the system ink supply to maintain substantially constant viscosity of the system ink supply.
a supply of fresh ink which is located in proximity to, but segregated from the system ink supply for exposure to common temperature conditions:
means selectively operable for delivering ink from either the system ink supply or said fresh ink supply to the nozzle to produce droplets;
means for sensing the velocity of the droplets means for sensing a first pressure applied to ink delivered from said fresh ink supply to produce having a predetermined velocity and a second pressure applied to ink delivered from said system ink supply to produce droplets having said same predetermined velocity; and means responsive to a difference between said first and second pressures to mix a selected quantity of additive with the ink in the system ink supply to maintain substantially constant viscosity of the system ink supply.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US770,597 | 1991-10-03 | ||
| US07/770,597 US5418557A (en) | 1991-10-03 | 1991-10-03 | Drop quality control system for jet printing |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2079419A1 true CA2079419A1 (en) | 1993-04-04 |
Family
ID=25089104
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002079419A Abandoned CA2079419A1 (en) | 1991-10-03 | 1992-09-29 | Drop quality control system for jet printing |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5418557A (en) |
| EP (1) | EP0536000A2 (en) |
| JP (1) | JPH05201025A (en) |
| CA (1) | CA2079419A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5517216A (en) * | 1992-07-28 | 1996-05-14 | Videojet Systems International, Inc. | Ink jet printer employing time of flight control system for ink jet printers |
| US5489925A (en) * | 1993-05-04 | 1996-02-06 | Markem Corporation | Ink jet printing system |
| US5444472A (en) * | 1993-09-07 | 1995-08-22 | Matthews International Corporation | Method of and an apparatus for using an ink concentrate in an ink jet printing arrangement |
| JP3402351B2 (en) * | 1996-08-05 | 2003-05-06 | セイコーエプソン株式会社 | Ink jet recording device |
| DE19906826B4 (en) * | 1998-09-01 | 2005-01-27 | Hewlett-Packard Co. (N.D.Ges.D.Staates Delaware), Palo Alto | Pressure-based ink level detector and method for detecting an ink level |
| FR2792874B1 (en) * | 1999-04-28 | 2001-06-22 | Imaje Sa | INK-JET PRINTER AND METHOD FOR MANAGING THE QUALITY OF THE INK OF SUCH A PRINTER |
| RU2197717C2 (en) * | 2000-12-29 | 2003-01-27 | Безруков Виктор Иванович | Hydraulic system of electric ink-drop and-jet printer, trap for unused drops for hydraulic system of electric ink-drop and-jet printer |
| US6883904B2 (en) * | 2002-04-24 | 2005-04-26 | Eastman Kodak Company | Apparatus and method for maintaining constant drop volumes in a continuous stream ink jet printer |
| CA2408108A1 (en) * | 2002-10-15 | 2004-04-15 | Adam I. Pinard | Printing fluid delivery system |
| US7922314B2 (en) * | 2004-07-30 | 2011-04-12 | Hewlett-Packard Development Company, L.P. | Printing mechanism and method of ink formulation |
| US7163283B2 (en) * | 2004-10-21 | 2007-01-16 | Eastman Kodak Company | Reuse of solvent startup/shutdown fluid for concentration control |
| US7416293B2 (en) * | 2005-02-18 | 2008-08-26 | Hewlett-Packard Development Company, L.P. | Ink recirculation system |
| US7530663B2 (en) * | 2005-10-11 | 2009-05-12 | Silverbrook Research Pty Ltd | Method of removing particulates from a printhead using a rotating roller |
| US7506952B2 (en) * | 2005-10-11 | 2009-03-24 | Silverbrook Research Pty Ltd | Method of removing particulates from a printhead using film transfer |
| GB2447919B (en) | 2007-03-27 | 2012-04-04 | Linx Printing Tech | Ink jet printing |
| GB0720131D0 (en) * | 2007-10-12 | 2007-11-28 | Videojet Technologies Inc | Ink jet printing |
| EP2082879B2 (en) * | 2008-01-28 | 2020-02-12 | Hitachi Industrial Equipment Systems Co., Ltd. | Ink jet recording device |
| US8210665B2 (en) * | 2008-04-18 | 2012-07-03 | Eastman Kodak Company | Constant flow valve mechanism |
| JP5274172B2 (en) * | 2008-09-17 | 2013-08-28 | 株式会社日立産機システム | Inkjet recording device |
| US8231212B2 (en) * | 2009-04-09 | 2012-07-31 | Plastipak Packaging, Inc. | Ink delivery system |
| US8360566B2 (en) * | 2009-04-09 | 2013-01-29 | Plastipak Packaging, Inc. | Method for printing |
| WO2011020022A1 (en) * | 2009-08-13 | 2011-02-17 | Sun Chemical Corporation | Temperature control in gravure and flexographic printing by aqueous fluid injection into the ink |
| US20130167940A1 (en) * | 2012-01-03 | 2013-07-04 | Gil LAVIE | Apparatus and method for pressure regulation |
| US8721057B2 (en) * | 2012-10-11 | 2014-05-13 | Xerox Corporation | System for transporting phase change ink using a thermoelectric device |
| PT3071413T (en) * | 2013-11-19 | 2020-02-28 | Archroma Ip Gmbh | Inkjet printing system |
| JP6338861B2 (en) * | 2014-01-08 | 2018-06-06 | 株式会社日立産機システム | Inkjet recording device |
| CN107206798B (en) | 2015-04-17 | 2019-03-26 | 惠普发展公司，有限责任合伙企业 | Printing equipment and supporting member for printing equipment |
| WO2018199888A1 (en) * | 2017-04-24 | 2018-11-01 | Hewlett-Packard Development Company, L.P. | Fluid ejection dies including strain gauge sensors |
| EP3741571A1 (en) * | 2019-05-24 | 2020-11-25 | Paul Leibinger GmbH & Co. KG Nummerier- und Markierungssysteme | Method for monitoring and adjusting viscosity of the ink during operation of a continuous inkjet printer and continuous inkjet printer for carrying out such a method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4067020A (en) * | 1976-09-20 | 1978-01-03 | A. B. Dick Company | Noninterrupt ink transfer system for ink jet printer |
| JPS56126170A (en) * | 1980-03-07 | 1981-10-02 | Ricoh Co Ltd | Ink viscosity detecting method in ink jet printer |
| JPS56136381A (en) * | 1980-03-28 | 1981-10-24 | Sharp Corp | Control of viscosity of jet ink |
| JPS5981177A (en) * | 1982-06-17 | 1984-05-10 | Ricoh Co Ltd | Ink viscosity controller in ink jet printer |
| GB8310711D0 (en) * | 1983-04-20 | 1983-05-25 | Cutatlas Ltd | Droplet depositing apparatus |
| FR2553341B1 (en) * | 1983-10-13 | 1987-06-12 | Imaje Sa | INK SUPPLY CIRCUIT FOR AN INK JET PRINTHEAD |
| US4555712A (en) * | 1984-08-03 | 1985-11-26 | Videojet Systems International, Inc. | Ink drop velocity control system |
| US4825228A (en) * | 1986-03-17 | 1989-04-25 | Gloeeckler Gerhard | Method of, and apparatus for, regulating ink viscosity in an ink jet printing system |
| FR2619753B2 (en) * | 1986-12-10 | 1990-08-31 | Imaje Sa | FLUID SUPPLY CIRCUIT OF A PRINTHEAD EQUIPPED WITH A MULTIFUNCTIONAL CELL COMPRISING A VARIABLE VOLUME CHAMBER |
| GB8708884D0 (en) * | 1987-04-14 | 1987-05-20 | Domino Printing Sciences Plc | Control of ink jet printing system |
| GB8725465D0 (en) * | 1987-10-30 | 1987-12-02 | Linx Printing Tech | Ink jet printers |
| US4860027A (en) * | 1988-03-18 | 1989-08-22 | A. B. Dick Company | Ink drop control system with temperature compensation |
| US4827280A (en) * | 1988-08-09 | 1989-05-02 | A. B. Dick Company | Flow rate control system |
-
1991
- 1991-10-03 US US07/770,597 patent/US5418557A/en not_active Expired - Fee Related
-
1992
- 1992-09-29 CA CA002079419A patent/CA2079419A1/en not_active Abandoned
- 1992-10-05 JP JP4266320A patent/JPH05201025A/en active Pending
- 1992-10-05 EP EP19920309065 patent/EP0536000A2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| EP0536000A3 (en) | 1994-01-26 |
| US5418557A (en) | 1995-05-23 |
| EP0536000A2 (en) | 1993-04-07 |
| JPH05201025A (en) | 1993-08-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |