EP0221452A1 - Elektrostatischer Bilddruckkopf - Google Patents
Elektrostatischer Bilddruckkopf Download PDFInfo
- Publication number
- EP0221452A1 EP0221452A1 EP86114690A EP86114690A EP0221452A1 EP 0221452 A1 EP0221452 A1 EP 0221452A1 EP 86114690 A EP86114690 A EP 86114690A EP 86114690 A EP86114690 A EP 86114690A EP 0221452 A1 EP0221452 A1 EP 0221452A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- electrodes
- counter
- recording medium
- electrode
- electrostatic
- 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.)
- Granted
Links
- 230000008878 coupling Effects 0.000 claims abstract description 19
- 238000010168 coupling process Methods 0.000 claims abstract description 19
- 238000005859 coupling reaction Methods 0.000 claims abstract description 19
- 239000004020 conductor Substances 0.000 claims description 3
- 229920001971 elastomer Polymers 0.000 claims description 2
- 239000000806 elastomer Substances 0.000 claims description 2
- 239000013536 elastomeric material Substances 0.000 claims description 2
- 239000011810 insulating material Substances 0.000 claims description 2
- 239000011248 coating agent Substances 0.000 claims 1
- 238000000576 coating method Methods 0.000 claims 1
- 230000000750 progressive effect Effects 0.000 abstract 1
- 239000010408 film Substances 0.000 description 10
- 230000005684 electric field Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000010411 cooking Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Images
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
- B41J2/385—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material
- B41J2/39—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material using multi-stylus heads
- B41J2/395—Structure of multi-stylus heads
Definitions
- the present invention relates to an electrostatic image printing head.
- Such electrostatic printheads make it possible to gradually create a latent electrostatic image on a moving dielectric recording medium by means of ionic discharges.
- direct electrostatic printing requires a special paper consisting of a conductive base covered by a thin dielectric film.
- a latent electrostatic image is created on the special paper by ionic discharge in the air by means of a row of small electrodes brought to high voltage.
- the latent image is inked, for example using a magnetic brush carrying powdered ink, then fixed on the special paper by pressure and / or by cooking.
- a high voltage is created between at least one of the electrodes and at least one counter-electrode placed nearby so that the resulting electric field at the electrode is perpendicular to the surface of the special paper.
- the counter-electrodes are placed on the same side of the special paper as the electrodes and the discharge takes place by the capacitive effect of the counter-electrodes through the dielectric film with which the special paper is provided and due to conduction of the conductive base of this special paper.
- the individual electrodes used in the print head are of very small dimensions and in large number, for an image line of given length, so as to allow for example the printing of eight dots per millimeter.
- the high voltage necessary for ionic discharges is preferably shared between electrodes and counter-electrodes, as the discharges only occur from a threshold value of the high voltage, it is arranged so that the voltage applied separately to a electrode or counter electrode is insufficient to cause a discharge alone and therefore an impression.
- the electrodes are aligned in bundles on at least one row, the electrodes of the same row of the bundles of the same row being interconnected.
- the counter electrodes are distributed along the bundles.
- a relatively large separation for example from 0.2 to 0.5 millimeter, is necessary between neighboring counter-electrodes because of the voltage values to be switched. This adversely affects printing when the requested resolution is high.
- the conductivity of the conductive base formed by the special paper there is a decrease in the electric field in the areas where the electrodes are in front of a space between counter-electrodes.
- the latent image is created on a thin insulating film, then revealed by inking according to a process identical to that mentioned above.
- the revealed image is then transferred and fixed on a sheet of plain paper, for example by pressing the sheet on the inked insulating film.
- the arrangement of the electrodes used for direct electrostatic writing is also suitable for indirect electrostatic writing, it is generally not the same with regard to the arrangement of the counter-electrodes since in this case neither the insulating film nor the paper are conductive.
- the conventional solution in indirect electrostatic writing consists in passing the insulating film, where the latent image is created, between the electrodes and the counter-electrodes which face each other.
- this solution has drawbacks, linked in particular to the complexity of the tension control system of the assembly and to the need for precise positioning of the counter-electrodes relative to the electrodes, whereas it is advantageous with this solution. ability to spread the electrodes of the counter electrodes to place the insulating film or remove it during regular film replacements that the user must make.
- the present invention therefore provides an electrostatic image printing head on a recording medium, in particular of the plain paper type, in which the electrodes and counter-electrodes necessary for ionic discharge are arranged on the same side of the recording medium. .
- the printhead conventionally comprises, firstly, at least one row of individual electrodes arranged in regular pitch and organized in n groups distributed in two networks, the electrodes having the same positions in the groups of a network being interconnected between they.
- the recording head conventionally comprises, secondly, at least one set of counter-electrodes aligned in parallel with the individual electrodes and each assigned to at least one group of electrodes which it runs along, so as to create a latent image on a insulating recording medium, scrolling flush with these electrodes and counter-electrodes, by ionic discharge between at least one electrode and at least one counter-electrode brought respectively to high-voltage potentials of opposite polarities by high-voltage pulses of ordered.
- the electrostatic printing head comprises a rotary coupling electrode which is made of conductive material and brought to a medium-voltage direct potential, of the same polarity as the high-voltage pulses applied to the counter-electrodes, said coupling electrode being pressed against the recording medium in line with the electrodes and counter-electrodes, on the other side of the latter relative to the recording medium.
- an electrostatic print head usually comprises a plurality of electrodes E aligned in at least one row along which are arranged at least one and here two rows of counter CE electrodes which border the row or rows of electrodes seen here at the end and by their active end, as well as the counter-electrodes.
- the electrodes and counter-electrodes are intended to come flush with the support for recording latent images on the same side of the strip that this support forms.
- the electrodes E which are in large number, for example 1728, are divided into n groups distributed in two networks and preferably comprising the same number r of electrodes, for example 36 groups of 48 electrodes, the number r being chosen equal to four in Figure 1 for reasons of simplification of the figure.
- the electrodes E of the same rank, in the different groups of a network are interconnected with one another, such as for example the electrodes E13, E33 or E23, En3.
- the electrodes of each network are energized by 1D or 2D switches which each serve a group of interconnected electrodes, such as the switch 1D3 for the electrodes E13, E33 given above as an example.
- a zero voltage OV is normally applied by each switch D to the electrodes to which it is connected, in the absence of individual control concerning them for a printing need.
- the latter is actuated so as to bring this electrode and those which are interconnected with it to a potential high voltage -V / 2, of lower value and here half of the high voltage V of threshold necessary for an ionic discharge of impression.
- the counter electrodes CE other than those at the end CE1, CE1 'and CEP, CEP', are arranged along electrodes belonging to two successive groups, such as the counter electrodes CE2, CE2 'along the electrodes E13, E14 from group 1 and E21, E22 from group 2.
- the counter-electrodes are energized by switches C, here referenced from C1 to Cp, which are shown each connected to a pair of interconnected counter-electrodes of the same rank, such as C1 to the CE1 counter-electrodes. , CE1 '.
- a zero voltage OV is normally applied by each switch C to the counter-electrodes to which it is connected, in the absence of individual control concerning them for printing.
- a print command actuates the switch C, concerned, so as to bring the counter-electrodes which it serves to a high voltage potential + V / 2.
- the ionic impression discharge is therefore obtained by setting the potential -V / 2 of an electrode and the potential + V / 2 of the counter-electrodes which runs along it.
- the recording medium 1 is of the conductive layer 1C type covered with a dielectric layer 1D intended to be pressed against the electrode / counter-electrode assembly to store point charges, the conductive layer serving as a path. the least resistive between an electrode E and the neighboring counter electrodes CE and CE ′, for ionic discharge, via the dielectric layer (FIG. 2).
- the recording medium 1 is a thin insulating film used as an intermediate for the formation of latent images, subsequently transferred to a final medium generally made of plain paper.
- an EC coupling electrode is provided.
- rotary such as EC1 in FIG. 2, which is brought to a direct potential V1 of the same polarity as the control pulses applied to the counter-electrodes, so as to associate its action with theirs in the event of control.
- the continuous potential + V1 is chosen with a value much lower than the value + V / 2 so as not to allow the triggering of an ionic discharge between an electrode E and the coupling electrode, it is for example of the order from one hundred to two hundred and fifty volts for a voltage V of the order of five hundred to six hundred volts.
- the coupling electrode EC is arranged transversely to the direction of movement of the recording medium and covers all of the electrodes E and counter electrodes CE, of which it extends beyond the rows of electrodes and counter electrodes, these these being of course also arranged transversely with respect to the direction of movement of the recording medium, in a block of insulating material 2 which keeps them in position relative to each other.
- the recording medium is generally constituted by a very smooth thin film, a small air gap 3 is provided under the electrodes between them and the recording medium, this interval is usually obtained by grooving the block 2 to the right of the electrodes E.
- the coupling electrode EC1 is constituted by an endless strip of flexible resistive material, of the charged elastomer type, the resistivity of which is for example of the order of 106 to 107 ohm.centimeter.
- This strip electrode is freely wound around carrier rollers 4 here three in number which allow its tension and for two of them its plating against the recording medium 1 on and around the ends of the electrodes and counter-electrodes.
- the coupling electrode EC1 is brought to potential + V1, for example at one of its carrier rollers by contact using means known per se, of the wiper type or connection by ring and wiper.
- the support assembly 2 rollers 4 and CE1 counter electrode is mechanically positioned in a usual support frame, not shown, which will not be specified here insofar as this structure has only an indirect relationship with the invention.
- a cylindrical EC2 coupling electrode is replaced by the endless belt provided in FIG. 2.
- This coupling electrode EC2, arranged transversely or direction of movement of the recording medium 1 is produced by a tube made of flexible material having for example a hardness less than thirty shores and a diameter of the order of six centimeters.
- the flexible tube obtained is for example made of an elastomeric material having a resistivity of the order of 106 to 107 ohm-centimeter; in the alternative embodiment presented here the flexible tube 5, mounted idly on an axis 6, is covered by an outer layer of constant thickness with a value for example between 0.1 and several millimeters which has the required resistivity and which is connected to the potential + V1, for example by a ring system associated with the tube and fixed wiper which is not reproduced here because of its classicism.
- the coupling electrode EC2 is mechanically pressed for example by a spring system against the recording medium itself applied against the assembly formed by the electrodes, the counter-electrodes and the block part which contains them, it deforms under pressure so as to cover said electrodes and counter electrodes.
- a printhead as defined above which allows printing on any support, after inking the latent electrostatic image, by transferring this inked image to the final support which must carry it, also allows printing on special composite paper comprising a dielectric layer and a conductive layer joined together.
Landscapes
- Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8515978 | 1985-10-28 | ||
FR8515978A FR2589273B1 (fr) | 1985-10-28 | 1985-10-28 | Tete d'impression electrostatique d'image |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0221452A1 true EP0221452A1 (de) | 1987-05-13 |
EP0221452B1 EP0221452B1 (de) | 1990-05-02 |
Family
ID=9324262
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP86114690A Expired - Lifetime EP0221452B1 (de) | 1985-10-28 | 1986-10-23 | Elektrostatischer Bilddruckkopf |
Country Status (4)
Country | Link |
---|---|
US (1) | US4727386A (de) |
EP (1) | EP0221452B1 (de) |
DE (1) | DE3670792D1 (de) |
FR (1) | FR2589273B1 (de) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0329965A (ja) * | 1989-06-28 | 1991-02-07 | Matsushita Graphic Commun Syst Inc | 静電潜像形成装置 |
US4977416A (en) * | 1989-09-21 | 1990-12-11 | Rastergraphics, Inc. | Integrated thick film electrostatic writing head |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0124856A1 (de) * | 1983-05-09 | 1984-11-14 | Telic Alcatel | Elektrostatischer Druckkopf |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5814160A (ja) * | 1981-07-17 | 1983-01-26 | Ricoh Co Ltd | 静電記録方法 |
-
1985
- 1985-10-28 FR FR8515978A patent/FR2589273B1/fr not_active Expired
-
1986
- 1986-10-23 EP EP86114690A patent/EP0221452B1/de not_active Expired - Lifetime
- 1986-10-23 DE DE8686114690T patent/DE3670792D1/de not_active Expired - Lifetime
- 1986-10-28 US US06/923,928 patent/US4727386A/en not_active Expired - Fee Related
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0124856A1 (de) * | 1983-05-09 | 1984-11-14 | Telic Alcatel | Elektrostatischer Druckkopf |
Also Published As
Publication number | Publication date |
---|---|
US4727386A (en) | 1988-02-23 |
DE3670792D1 (de) | 1990-06-07 |
FR2589273A1 (fr) | 1987-04-30 |
EP0221452B1 (de) | 1990-05-02 |
FR2589273B1 (fr) | 1987-12-11 |
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