EP0265114A2 - Ink jet printer and its printing method - Google Patents
Ink jet printer and its printing method Download PDFInfo
- Publication number
- EP0265114A2 EP0265114A2 EP87308840A EP87308840A EP0265114A2 EP 0265114 A2 EP0265114 A2 EP 0265114A2 EP 87308840 A EP87308840 A EP 87308840A EP 87308840 A EP87308840 A EP 87308840A EP 0265114 A2 EP0265114 A2 EP 0265114A2
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- EP
- European Patent Office
- Prior art keywords
- ink
- electrode
- jet printer
- recording
- ink jet
- 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.)
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Classifications
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- 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
- B41J2/21—Ink jet for multi-colour printing
- B41J2/2121—Ink jet for multi-colour printing characterised by dot size, e.g. combinations of printed dots of different diameter
- B41J2/2128—Ink jet for multi-colour printing characterised by dot size, e.g. combinations of printed dots of different diameter by means of energy modulation
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- 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
- B41J2/06—Ink jet characterised by the jet generation process generating single droplets or particles on demand by electric or magnetic field
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- 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
- B41J2/06—Ink jet characterised by the jet generation process generating single droplets or particles on demand by electric or magnetic field
- B41J2002/061—Ejection by electric field of ink or of toner particles contained in ink
Definitions
- the present invention relates to an ink jet printer wherein ink drops are flied by electrostatic means thereby printing is performed, and more particularly to an ink jet printer having structure suited to printing with gradation and its printing method.
- an ink jet printer exists wherein ink drops are selectively flied by electrostatic means, the flied ink drops adhere to a recording medium so as to form dotd, and an image is formed by selective gathering of the dots.
- the dot diameter on the recording paper is uniform, the image cannot have gradation in usual method. Consequently, various manners have been thought in order to give gradation to the image.
- so-called dither method is frequently used in the prior art. That is, one picture element is divided into a plurality of matrices and a dot is formed in each matrix. In order to obtain the picture element of high density, the number of dots formed within the picture element is increased. On the contrary, in order to obtain the picture element of low density, the number of dots is decreased.
- the density of one picture element is arbitrarily varied, and gradation is given to the whole image being gathering of picture elements.
- the above-mentioned dither method is also used as a color printing manner. More concretely, dot formed in each matrix by dividing one picture element is made one of the three primary colors. Selection of one color in the three primary colors is arbitrary. Thereby, color of one picture element as a whole is expressed in one color among the three primary colors or in mixed color of these colors. Particularly, the mixed color can be expressed with variety as the number of matrices is increased.
- FIG. 10 shows a time lapse variation diagram of the top end portion of the recording electrode illustrating relation between the acting time of the electrostatic force and the ink flying state.
- a recording electrode 20 and an opposite electrode 21 are opposed through a recording paper 22.
- the recording electrode 20 is formed by an ink impregnated member, and part except for a top end portion 20a is immersed in an ink liquid (not shown). Consequently, the ink liquid is impregnated in the recording electrode 20, and turned round the top end portion 20a and held.
- the voltage of the pulse width between the time t1 and the time t5 is applied to the recording electrode 20 and the opposite electrode 21.
- the ink liquid held in the top end portion 20a between the time t1 and the time t5 becomes ink drops 23 flying in stringy form towards the opposite electrode 21 and adheres to the recording paper 22 so as to form a dot.
- the ink liquid in the top end portion 20a is attracted to the opposite electrode 21 by means of the electrostatic force.
- the ink liquid flies in the ink drops 23 by the time of the pulse width of the voltage applied between both electrodes. Consequently, the width of the voltage pulse supplied between both electrodes is varied, thereby the flying amount of the ink liquid is varied resulting in variation of the diameter of the dot formed on the recording paper 22.
- the dot diameter is adjusted regarding each dot thereby the whole image is provided with gradation.
- a first object of the invention is to provide an ink jet printer and its printing method to enable natural image expression when the printing with gradation is performed.
- a second object of the invention is to provide an ink jet printer and its printing method to enable the smooth image expression when the printing with gradation is performed.
- ink is flied under condition of the ink flying in mist form according to relation of the electric field value between a recording electrode and an opposite electrode and resistivity value of the ink, and a number of fine mist particles by the ink are gathered on a recording medium thereby dots are formed.
- pulse width of the voltage applied between the recording electrode and the opposite electrode is varied or when the voltage value is varied, the amount of ink flying from the recording electrode is adjusted and the number of mist particles to form the dot is varied, thereby tone is produced on the dot and degradation is produced on the image.
- diameter of each dot as one picture element is constant, spacing between one dot and other dot can be held to a constant spacing with high density so as to enable the natural and smooth image expression.
- FIGS. 1 through 7(a)(b) A first embodiment of the invention will be described based on FIGS. 1 through 7(a)(b).
- a case 1 of cabinet form is installed, and two guide shafts 2 are arranged horizontally within the case 1.
- a carrier 3 is slidably installed to these guide shafts 2, and a printer head 4 is held on the carrier 3.
- An opposite electrode 5 of lateral extending form is mounted horizontally along the guide shafts 2 at center portion within the case 1.
- tracks 7 feeding a recording paper 6 as a recording medium guided between the opposite electrode 5 and the printer head 4 are installed.
- Operation knobs 8 projecting outward are coupled with these tracks 7.
- the printer head 4 will be herein described in detail based on FIG. 1.
- External form of the printer head 4 is a case 9 of cabinet form, and ink 10 is stored in the case 9.
- resistivity is slightly less than 106 ⁇ 107 ⁇ ⁇ cm
- viscosity is 30 cp or less
- surface tension is 20 ⁇ 30 dyn/cm.
- a plurality of recording electrodes 11 immersed in the ink 10 and having top end portions 11a exposed to outside are aligned longitudinally.
- Each of these recording electrodes 11 is constituted in that polyester fibers are twisted and copper is coated around the polyester fibers thereby conductivity and ink impregnable property are provided.
- Each recording electrode 11 has sectional diameter of about 1 mm, and the top end portion 11a is tapered.
- the tip of the tapered top end portion 11a is provided with curvature, and the curvature radius is 50 ⁇ 100 ⁇ m.
- the top end portion 11a of the recording electrodes 11 are disposed in opposition to the opposite electrode 5 with spacing of 500 ⁇ 100 ⁇ m.
- a switch circuit 12 is connected to each recording electrode 11.
- One change-over contact of the switch circuit 12 is earthed to the ground G.
- Other change-over contact of the switch circuit 12 is connected to the opposite electrode 5 through two power source 13, 14 with the connection neutral point earthed to the ground G.
- These power sources 13, 14 generate voltage of 1 kV ⁇ 3.2 kV between the opposite electrode 5 and the recording electrode 11 when the switch circuit 12 is turned on.
- an image signal circuit 15 is connected to the switch circuit 12, and a pulse width control circuit 16 as a printing control circuit is interposed between the switch circuit 12 and the image signal circuit 15.
- the pulse width control circuit 16 generates printing control signal which varies the voltage pulse width of voltage applied to the recording electrode 11 and the opposite electrode 5 in response to the image signal.
- the switch circuit 12 is turned on and voltage is applied between the recording electrode 11 and the opposite electrode 5.
- the ink 10 within the case 9 is soaked into the recording electrode 11 and supplied up to the top end portion 11a. Consequently, the ink 10 supplied to the top end portion 11a is subjected to the electrostatic force and flies towards the opposite electrode 5.
- the flying ink 10 adheres to the recording paper 6 and forms a dot 17. Diameter of such a dot 17 is about 300 ⁇ m. Selective gathering of these dots 17 forms an image on the recording paper 6.
- the ink 10 turning round te top end portion 11a of the recording electrode 11 flies in mist form from the top end portion 11a. Because the voltage from the electrodes 13, 14 is applied between the recording electrode 11 and the opposite electrode 5 in condition of the ink 10 flying in mist form corresponding to the physical properties of the ink 10. More concretely, as shown in FIG. 3, in the region A the ink 10 remaining in the liquid state flies in stringy form, whereas in the region B the ink 10 flies in mist form. For example, if the ink 10 has the resistivity of 107 ⁇ ⁇ cm, voltage of about 3 kV or more is applied between both electrodes thereby flying of the ink 10 in mist form is produced. Although the graph of FIG.
- FIG. 4 shows the state of the ink 10 in time lapse where the ink 10 flies in mist form from the top end portion 11a of the recording electrode 11.
- the pulse width of the voltage set by the pulse width control circuit 16 is that between the time t1 and the time t5 as shown in FIG. 5. Consequently, the ink 10 flies in mist particles 10a between the time t1 and the time t5, and then adheres completely to the recording paper 6 and becomes the form as the dots 17 at the time t8.
- the flying time of the ink 10 coincides with the pulse width of the voltage.
- the pulse width of the voltage i.e., the voltage supply time between both electrodes is varied by the pulse width control circuit 16 thereby the flying time of the ink 10 is varied.
- the number of the flying mist particles 10a is varied thereby the density is expressed in the dots 17. If the density of the dots 17 is adjusted throughout the whole image, the image is provided with the gradation. Relation of the voltage supply time and the density of the dots 17 is shown in FIG. 6 in a graph.
- FIG. 7(a) shows an enlarged view of the dots 17 formed when the voltage supply time is made long
- FIG. 7(b) shows an enlarged view of the dots 17 formed when the voltage supply time is made short.
- FIG. 7 is a model view illustrating concept for comparison, and in the dot 17 of the actual state, each mist particle 10a has smaller diameter and the distribution state has higher density.
- the density of the dot 17 is produced only by difference of the number of the mist particles 10a as elements to constitute the dot 17, and not dependent on difference of the diameter of the dot 17. Consequently, the outer diameter of the dot 17 is equal regarding all dots 17 in the image.
- the distance between dots 17 is always held constant, and the density of each dot 17 can be varied.
- the connection between the adjacent dots 17 becomes smooth thereby quite natural gradation expression can be realized.
- the dot 17 is a minimum picture element to constitute the image, the high density formation is easy.
- the density can be sufficiently expressed even when the diameter of the dot 17 is made as small as about 300 ⁇ m in the embodiment, thereby the image formation at higher density is possible. Consequently, not only the smoothness of the gradation expression but also the smoothness of the whole image by the high density formation of one picture element can be realized, thereby more natural image formation becomes possible.
- the ink 10 having the resistivity value of slightly less than 106 ⁇ 107 ⁇ ⁇ cm is used. Consequently, as clearly seen from the graph of FIG. 3, the ink 10 flies in mist form by the supply voltage with value of slightly less than 2 kV to about 3 kV. If the value of the supply voltage is increased, spark may be produced between the opposite electrode 5 and the recording electrode 5 resulting in the printing failure. However, the spark is not liable to occur by the supply voltage with value of about 3 kV, thereby the device of high safety can be realized. Moreover, the consumption power can be saved in comparison to the case using the ink 10 of higher resistivity.
- the image signal circuit 15 is directly connected to the switch circuit 12 not through the pulse width control circuit 16, and a voltage variable circuit 18 is installed between the switch circuit 12 and the power source 13.
- the voltage variable circuit 18 varies the value of the voltage applied between the recording electrode 11 and the opposite electrode 5 in range of 2 kV ⁇ 4 kV.
- the ink 10 having the resistivity value of slightly less than 106 ⁇ ⁇ cm is used.
- the number of the flying mist particles 10a is varied by varying the voltage value using the voltage variable circuit 18.
- the voltage variable circuit 18 in the region where the value of the supply voltage is as high as nearly 4 kV, not only the number of the flying mist particles 10a but also the flying state may be spread.
- FIG. 8(a)(b) shows such state. Consequently, in the gradation expression in the actual state, not only the variation of the density of the dot 17 in itself but also the variation of the diameter of the dot 17 realized by the spread in the flying state of the mist particles 10a may be utilized.
- a third embodiment of the invention will now be described.
- the same parts as those of the first embodiment are designated by the same reference numerals, and the description shall be omitted.
- a process color ink of yellow, mazenta and cyan is used as the ink 10.
- the mist particles 10a of these colors are overlapped on the same dot 17, and an arbitrary color can be expressed by the distribution of the amount of these mist particles 10a.
- the mist particles 10a of each color are distributed uniformly in the area of the dot 17 thereby quite natural color expression becomes possible. Consequently, when the image expression having the smooth gradation by the high density of the dot 17 and the equal diameter of the dot 17 is maintained, the natural color printing becomes possible.
- FIG. 9 shows a modification.
- the density level of each color in one dot 17 is assumed that yellow component is at c level, magenta component is at b level, and cyan component is at a level, black component exists at equal amount of each color.
- the black component at d level lower than the c level being the minimum level is contained in the dot 17, and components at level lower than the d level are excluded regarding other colors.
- the dot 17 is formed in the same color as the case that components of three colors, yellowm magenta and cyan, only exist at c level, b level and c level respectively.
- a fourth embodiment of the invention will be described.
- the same parts as those in the second embodiment are designated by the same reference numerals, and the description shall be omitted.
- the fourth embodiment while the printer head 4 is moved in the main scanning direction, voltage is applied between the recording electrode 11 and the opposite electrode 5 continuously by an arbitrary time. In this constitution, not only the dot 17 but also the line can be drawn on the recording paper 6. Consequently, the image is formed by combination of plural lines.
- the supply voltage value between the recording electrode 11 and the opposite electrode 5 per unit time is varied by the voltage variable circuit 18. Operation of the voltage variable circuit 18 is by analog signals. Or, the scanning speed is varied stepwise, thereby the pulse width of the supply voltage per unit time is varied.
- the lines drawn on the recording paper 6 have gradation without varying the thickness. In this case, however, voltage is applied between the opposite electrode 5 and the recording electrode 11 in the range where the value of the supply voltage is as low as nearly 2 kV. Because the thickness of the lines drawn on the recording paper 6 does not become constant if the voltage is applied at the region nearly equal to 4 kV.
- the lines drawn on the recording paper 6 may be colored. That is, in similar manner to the third embodiment, the mist particles 10a in respective colors, yellow, magenta and cyan, are formed in arbitrary mixing ratio on the same line. In this constitution, the color variation and the gradation variation can be simultaneously expressed on the lines drawn in the scanning direction.
- the pulse width control circuit 16 or the voltage variable circuit 18 has been used as the printing control circuit in the above-mentioned embodiments, the actual use is not limited to these circuits, but other means may be used.
- the electric amount between both electrodes may be varied by means for varying the current value between the recording electrode and the opposite electrode.
Abstract
Description
- The present invention relates to an ink jet printer wherein ink drops are flied by electrostatic means thereby printing is performed, and more particularly to an ink jet printer having structure suited to printing with gradation and its printing method.
- In the prior art, an ink jet printer exists wherein ink drops are selectively flied by electrostatic means, the flied ink drops adhere to a recording medium so as to form dotd, and an image is formed by selective gathering of the dots. In such an ink jet printer, since the dot diameter on the recording paper is uniform, the image cannot have gradation in usual method. Consequently, various manners have been thought in order to give gradation to the image. As one of these, so-called dither method is frequently used in the prior art. That is, one picture element is divided into a plurality of matrices and a dot is formed in each matrix. In order to obtain the picture element of high density, the number of dots formed within the picture element is increased. On the contrary, in order to obtain the picture element of low density, the number of dots is decreased. Thus the density of one picture element is arbitrarily varied, and gradation is given to the whole image being gathering of picture elements.
- The above-mentioned dither method is also used as a color printing manner. More concretely, dot formed in each matrix by dividing one picture element is made one of the three primary colors. Selection of one color in the three primary colors is arbitrary. Thereby, color of one picture element as a whole is expressed in one color among the three primary colors or in mixed color of these colors. Particularly, the mixed color can be expressed with variety as the number of matrices is increased.
- On the other hand, as another manner to give gradation to the image, a device having structure that the dot diameter is varied thereby gradation is given to the whole image has been disclosed by the present applicant in Japanese patent application No. 60-153301 (JP A 62-13356) and Japanese patent application No. 60-153490 (JP A 62-13357). That is, strength of the electrostatic force acting to the ink or the acting time is varied thereby the flying amount of ink is varied so as to obtain the dot of any diameter. As an example of the device having structure of varying the acting time of the electrostatic force acting to the ink, FIG. 10 shows a time lapse variation diagram of the top end portion of the recording electrode illustrating relation between the acting time of the electrostatic force and the ink flying state. A
recording electrode 20 and anopposite electrode 21 are opposed through arecording paper 22. Therecording electrode 20 is formed by an ink impregnated member, and part except for atop end portion 20a is immersed in an ink liquid (not shown). Consequently, the ink liquid is impregnated in therecording electrode 20, and turned round thetop end portion 20a and held. In this state, as shown in FIG. 11 for example, the voltage of the pulse width between the time t₁ and the time t₅ is applied to therecording electrode 20 and theopposite electrode 21. The ink liquid held in thetop end portion 20a between the time t₁ and the time t₅ becomesink drops 23 flying in stringy form towards theopposite electrode 21 and adheres to therecording paper 22 so as to form a dot. Because the potential difference is produced between both electrodes and the imk liquid in thetop end portion 20a is attracted to theopposite electrode 21 by means of the electrostatic force. Thus the ink liquid flies in the ink drops 23 by the time of the pulse width of the voltage applied between both electrodes. Consequently, the width of the voltage pulse supplied between both electrodes is varied, thereby the flying amount of the ink liquid is varied resulting in variation of the diameter of the dot formed on therecording paper 22. Thus the dot diameter is adjusted regarding each dot thereby the whole image is provided with gradation. - Technical problems of the prior art in such constitution will now be described. When the dither method is used, since one picture element is constituted by gathering of a plurality of matrices, size of one picture element as a unit to constitute the image becomes large. Consequently, the density of the picture element becomes low and the quality of the image is deteriorated in natural state. Particularly, when the degradation is raised or when the color printing is performed in the color expression with variety, the number of matrices must be increased. In this case, the density of one picture element becomes lower.
- On the other hand, in the method that the dot diameter is varied thereby the whole image is provided with degradation, when the dot diameter is made small, a blank space between adjacent dots becomes wide thereby the image expression is deteriorated in the smoothness.
- A first object of the invention is to provide an ink jet printer and its printing method to enable natural image expression when the printing with gradation is performed.
- A second object of the invention is to provide an ink jet printer and its printing method to enable the smooth image expression when the printing with gradation is performed.
- In the present invention, in order to attain the foregoing objects, ink is flied under condition of the ink flying in mist form according to relation of the electric field value between a recording electrode and an opposite electrode and resistivity value of the ink, and a number of fine mist particles by the ink are gathered on a recording medium thereby dots are formed. When pulse width of the voltage applied between the recording electrode and the opposite electrode is varied or when the voltage value is varied, the amount of ink flying from the recording electrode is adjusted and the number of mist particles to form the dot is varied, thereby tone is produced on the dot and degradation is produced on the image. In this case, since diameter of each dot as one picture element is constant, spacing between one dot and other dot can be held to a constant spacing with high density so as to enable the natural and smooth image expression.
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- FIG. 1 is a longitudinal sectional view of a printer head as a first embodimen of the invention;
- FIG. 2 is a perspective view of a whole device;
- FIG. 3 is a graph illustrating relation of resistivity value of ink and supplu voltage value to state of ink;
- FIG. 4 is a side view of a recording electrode illustrating flying state of ink in time lapse state;
- FIG. 5 is a graph illustrating pulse width of supply voltage when ink is flied as in FIG. 4;
- FIG. 6 is a graph illustrating relation between pulse width of supply voltage and dot density;
- FIG. 7(a)(b) is a front view of dot in comparison of the case that pulse width of supply voltage is made long and made short;
- FIG. 8 is a longitudinal sectional view of a printer head as a second embodiment of the invention;
- FIG. 9(a)(b) is a side view illustrating state of ink flying from a recording electrode;
- FIG. 10 is a graph illustrating relation of ratio of density level of each color and black component in a modification of a third embodiment;
- FIG. 11 is a side view of a recording electrode illustrating flying state of ink in time lapse state in an example of the prior art; and
- FIG. 12 is a graph illustrating pulse width of supply voltage when ink is flied as in FIG. 9.
- A first embodiment of the invention will be described based on FIGS. 1 through 7(a)(b). A
case 1 of cabinet form is installed, and twoguide shafts 2 are arranged horizontally within thecase 1. Acarrier 3 is slidably installed to theseguide shafts 2, and aprinter head 4 is held on thecarrier 3. Anopposite electrode 5 of lateral extending form is mounted horizontally along theguide shafts 2 at center portion within thecase 1. On rear side of theopposite electrode 5,tracks 7 feeding arecording paper 6 as a recording medium guided between theopposite electrode 5 and theprinter head 4 are installed.Operation knobs 8 projecting outward are coupled with thesetracks 7. - The
printer head 4 will be herein described in detail based on FIG. 1. External form of theprinter head 4 is acase 9 of cabinet form, andink 10 is stored in thecase 9. As the physical properties of theink 10, resistivity is slightly less than 10⁶ ∼ 10⁷ Ω · cm, viscosity is 30 cp or less, and surface tension is 20 ∼ 30 dyn/cm. Within thecase 9, a plurality ofrecording electrodes 11 immersed in theink 10 and havingtop end portions 11a exposed to outside are aligned longitudinally. Each of theserecording electrodes 11 is constituted in that polyester fibers are twisted and copper is coated around the polyester fibers thereby conductivity and ink impregnable property are provided. Eachrecording electrode 11 has sectional diameter of about 1 mm, and thetop end portion 11a is tapered. The tip of the taperedtop end portion 11a is provided with curvature, and the curvature radius is 50 ∼ 100 µm. Thetop end portion 11a of therecording electrodes 11 are disposed in opposition to theopposite electrode 5 with spacing of 500 ∼ 100 µm. - A
switch circuit 12 is connected to eachrecording electrode 11. One change-over contact of theswitch circuit 12 is earthed to the ground G. Other change-over contact of theswitch circuit 12 is connected to theopposite electrode 5 through twopower source power sources opposite electrode 5 and therecording electrode 11 when theswitch circuit 12 is turned on. Furthermore, animage signal circuit 15 is connected to theswitch circuit 12, and a pulsewidth control circuit 16 as a printing control circuit is interposed between theswitch circuit 12 and theimage signal circuit 15. The pulsewidth control circuit 16 generates printing control signal which varies the voltage pulse width of voltage applied to therecording electrode 11 and theopposite electrode 5 in response to the image signal. - In such constitution, if the image signal is generated from the
image signal circuit 15, theswitch circuit 12 is turned on and voltage is applied between therecording electrode 11 and theopposite electrode 5. In this case, theink 10 within thecase 9 is soaked into therecording electrode 11 and supplied up to thetop end portion 11a. Consequently, theink 10 supplied to thetop end portion 11a is subjected to the electrostatic force and flies towards theopposite electrode 5. The flyingink 10 adheres to therecording paper 6 and forms adot 17. Diameter of such adot 17 is about 300 µm. Selective gathering of thesedots 17 forms an image on therecording paper 6. - On the other hand, the
ink 10 turning round tetop end portion 11a of therecording electrode 11 flies in mist form from thetop end portion 11a. Because the voltage from theelectrodes recording electrode 11 and theopposite electrode 5 in condition of theink 10 flying in mist form corresponding to the physical properties of theink 10. More concretely, as shown in FIG. 3, in the region A theink 10 remaining in the liquid state flies in stringy form, whereas in the region B theink 10 flies in mist form. For example, if theink 10 has the resistivity of 10⁷ Ω · cm, voltage of about 3 kV or more is applied between both electrodes thereby flying of theink 10 in mist form is produced. Although the graph of FIG. 3 shows condition of theink 10 flying in mist form according to relation of the supply voltage between therecording electrode 11 and the opposite electrode and the resistivity value of theink 10, other factors actually exist also in order that theink 10 flies in mist form. That is, theink 10 flies in mist form according to relation of the physical properties and the supply voltage between both electrodes, and the resistivity value of theink 10 is one factor only. - FIG. 4 shows the state of the
ink 10 in time lapse where theink 10 flies in mist form from thetop end portion 11a of therecording electrode 11. In this case, the pulse width of the voltage set by the pulsewidth control circuit 16 is that between the time t₁ and the time t₅ as shown in FIG. 5. Consequently, theink 10 flies inmist particles 10a between the time t₁ and the time t₅, and then adheres completely to therecording paper 6 and becomes the form as thedots 17 at the time t₈. Thus the flying time of theink 10 coincides with the pulse width of the voltage. Consequently, in the embodiment, the pulse width of the voltage, i.e., the voltage supply time between both electrodes is varied by the pulsewidth control circuit 16 thereby the flying time of theink 10 is varied. As a result of varying the flying time of theink 10, more concretely, the number of the flyingmist particles 10a is varied thereby the density is expressed in thedots 17. If the density of thedots 17 is adjusted throughout the whole image, the image is provided with the gradation. Relation of the voltage supply time and the density of thedots 17 is shown in FIG. 6 in a graph. FIG. 7(a) shows an enlarged view of thedots 17 formed when the voltage supply time is made long, and FIG. 7(b) shows an enlarged view of thedots 17 formed when the voltage supply time is made short. However, FIG. 7 is a model view illustrating concept for comparison, and in thedot 17 of the actual state, eachmist particle 10a has smaller diameter and the distribution state has higher density. - Noticing each dot 17, the density of the
dot 17 is produced only by difference of the number of themist particles 10a as elements to constitute thedot 17, and not dependent on difference of the diameter of thedot 17. Consequently, the outer diameter of thedot 17 is equal regarding alldots 17 in the image. Thus the distance betweendots 17 is always held constant, and the density of each dot 17 can be varied. When the distance density between thedots 17 is elevated, the connection between theadjacent dots 17 becomes smooth thereby quite natural gradation expression can be realized. - Moreover, since the
dot 17 is a minimum picture element to constitute the image, the high density formation is easy. Regarding this point, from the property of thedot 17 with the density varying for itself, the density can be sufficiently expressed even when the diameter of thedot 17 is made as small as about 300 µm in the embodiment, thereby the image formation at higher density is possible. Consequently, not only the smoothness of the gradation expression but also the smoothness of the whole image by the high density formation of one picture element can be realized, thereby more natural image formation becomes possible. - In addition, in the embodiment, the
ink 10 having the resistivity value of slightly less than 10⁶ ∼ 10⁷ Ω · cm is used. Consequently, as clearly seen from the graph of FIG. 3, theink 10 flies in mist form by the supply voltage with value of slightly less than 2 kV to about 3 kV. If the value of the supply voltage is increased, spark may be produced between theopposite electrode 5 and therecording electrode 5 resulting in the printing failure. However, the spark is not liable to occur by the supply voltage with value of about 3 kV, thereby the device of high safety can be realized. Moreover, the consumption power can be saved in comparison to the case using theink 10 of higher resistivity. - Next, a second embodiment of the invention will be described based on FIG. 8(a)(b). Same parts as those in the first embodiment are designated by the same reference numerals, and the description shall be omitted. In the second embodiment, the
image signal circuit 15 is directly connected to theswitch circuit 12 not through the pulsewidth control circuit 16, and avoltage variable circuit 18 is installed between theswitch circuit 12 and thepower source 13. Thevoltage variable circuit 18 varies the value of the voltage applied between therecording electrode 11 and theopposite electrode 5 in range of 2 kV ∼ 4 kV. Theink 10 having the resistivity value of slightly less than 10⁶ Ω · cm is used. Consequently, in this embodiment, in place of variation of the pulse width of the voltage, the number of the flyingmist particles 10a is varied by varying the voltage value using thevoltage variable circuit 18. In this case, in the region where the value of the supply voltage is as high as nearly 4 kV, not only the number of the flyingmist particles 10a but also the flying state may be spread. FIG. 8(a)(b) shows such state. Consequently, in the gradation expression in the actual state, not only the variation of the density of thedot 17 in itself but also the variation of the diameter of thedot 17 realized by the spread in the flying state of themist particles 10a may be utilized. - A third embodiment of the invention will now be described. The same parts as those of the first embodiment are designated by the same reference numerals, and the description shall be omitted. In the third embodiment, a process color ink of yellow, mazenta and cyan is used as the
ink 10. Themist particles 10a of these colors are overlapped on thesame dot 17, and an arbitrary color can be expressed by the distribution of the amount of thesemist particles 10a. Within onedot 17, themist particles 10a of each color are distributed uniformly in the area of thedot 17 thereby quite natural color expression becomes possible. Consequently, when the image expression having the smooth gradation by the high density of thedot 17 and the equal diameter of thedot 17 is maintained, the natural color printing becomes possible. - FIG. 9 shows a modification. When the density level of each color in one
dot 17 is assumed that yellow component is at c level, magenta component is at b level, and cyan component is at a level, black component exists at equal amount of each color. The black component at d level lower than the c level being the minimum level is contained in thedot 17, and components at level lower than the d level are excluded regarding other colors. In this constitution, thedot 17 is formed in the same color as the case that components of three colors, yellowm magenta and cyan, only exist at c level, b level and c level respectively. - Further, a fourth embodiment of the invention will be described. The same parts as those in the second embodiment are designated by the same reference numerals, and the description shall be omitted. In the fourth embodiment, while the
printer head 4 is moved in the main scanning direction, voltage is applied between therecording electrode 11 and theopposite electrode 5 continuously by an arbitrary time. In this constitution, not only thedot 17 but also the line can be drawn on therecording paper 6. Consequently, the image is formed by combination of plural lines. On the other hand, in the scanning time of theprinter head 4, the supply voltage value between therecording electrode 11 and theopposite electrode 5 per unit time is varied by thevoltage variable circuit 18. Operation of thevoltage variable circuit 18 is by analog signals. Or, the scanning speed is varied stepwise, thereby the pulse width of the supply voltage per unit time is varied. In this constitution, the lines drawn on therecording paper 6 have gradation without varying the thickness. In this case, however, voltage is applied between theopposite electrode 5 and therecording electrode 11 in the range where the value of the supply voltage is as low as nearly 2 kV. Because the thickness of the lines drawn on therecording paper 6 does not become constant if the voltage is applied at the region nearly equal to 4 kV. - As a modification, the lines drawn on the
recording paper 6 may be colored. That is, in similar manner to the third embodiment, themist particles 10a in respective colors, yellow, magenta and cyan, are formed in arbitrary mixing ratio on the same line. In this constitution, the color variation and the gradation variation can be simultaneously expressed on the lines drawn in the scanning direction. - Although the pulse
width control circuit 16 or thevoltage variable circuit 18 has been used as the printing control circuit in the above-mentioned embodiments, the actual use is not limited to these circuits, but other means may be used. For example, the electric amount between both electrodes may be varied by means for varying the current value between the recording electrode and the opposite electrode.
Claims (12)
a recording electrode having a top end portion supplied with ink;
an opposite electrode opposed to the recording electrode through a recording medium:
a power source applying voltage between the recording electrode and the opposite electrode in voltage range so that the ink flies in mist form; and
a printing control circuit which varies power amount supplied between the recording electrode and the opposite electrode.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP246160/86 | 1986-10-16 | ||
JP24616086A JPS6399952A (en) | 1986-10-16 | 1986-10-16 | Ink jet printer and its printing method |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0265114A2 true EP0265114A2 (en) | 1988-04-27 |
EP0265114A3 EP0265114A3 (en) | 1989-10-11 |
Family
ID=17144392
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP87308840A Withdrawn EP0265114A3 (en) | 1986-10-16 | 1987-10-06 | Ink jet printer and its printing method |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0265114A3 (en) |
JP (1) | JPS6399952A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8029103B2 (en) | 2008-01-29 | 2011-10-04 | Fuji Xerox Co., Ltd. | Liquid droplet ejection head for ejecting high viscosity liquid droplets, and liquid droplet ejection device |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2805775B2 (en) * | 1988-11-10 | 1998-09-30 | 神鋼電機株式会社 | Printing equipment |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1471780A (en) * | 1973-09-04 | 1977-04-27 | Xerox Corp | Ink printer |
DE3019012A1 (en) * | 1979-05-18 | 1980-11-20 | Ricoh Kk | High resolution ink jet printer - has jet electrode covered with ink and has focusing electrode behind paper |
EP0196820A1 (en) * | 1985-03-20 | 1986-10-08 | Tokyo Electric Co. Ltd. | Ink dot printer |
EP0208322A2 (en) * | 1985-07-11 | 1987-01-14 | Tokyo Electric Co., Ltd. | Ink jet printing device |
-
1986
- 1986-10-16 JP JP24616086A patent/JPS6399952A/en active Pending
-
1987
- 1987-10-06 EP EP87308840A patent/EP0265114A3/en not_active Withdrawn
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1471780A (en) * | 1973-09-04 | 1977-04-27 | Xerox Corp | Ink printer |
DE3019012A1 (en) * | 1979-05-18 | 1980-11-20 | Ricoh Kk | High resolution ink jet printer - has jet electrode covered with ink and has focusing electrode behind paper |
EP0196820A1 (en) * | 1985-03-20 | 1986-10-08 | Tokyo Electric Co. Ltd. | Ink dot printer |
EP0208322A2 (en) * | 1985-07-11 | 1987-01-14 | Tokyo Electric Co., Ltd. | Ink jet printing device |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8029103B2 (en) | 2008-01-29 | 2011-10-04 | Fuji Xerox Co., Ltd. | Liquid droplet ejection head for ejecting high viscosity liquid droplets, and liquid droplet ejection device |
Also Published As
Publication number | Publication date |
---|---|
JPS6399952A (en) | 1988-05-02 |
EP0265114A3 (en) | 1989-10-11 |
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