JP5504808B2 - Image forming apparatus and image forming method - Google Patents

Description

  The present invention relates to an image forming apparatus and an image forming method for forming an image on a rewritable display medium having an electrochromic material.

In recent years, the amount of information has increased due to the development of information equipment, and the importance of media capable of easily outputting a large amount of information has increased. Along with this, in addition to conventional means for outputting information on paper by means of hard copy methods such as ink jet and electrophotography, images can be displayed with low power consumption, collectively called so-called electronic paper or paper-like display. A small and lightweight reflective display device (hereinafter referred to as electronic paper) that can be displayed and rewritten is in the spotlight. In recent years, there is a strong expectation that electronic paper will become an alternative technology to hard copy on paper due to increasing awareness of environmental issues.
Image display and rewriting methods for electronic paper include a method that uses the movement of charged particles, a method that uses bistable liquid crystal, a method that switches images using a mechanical drive such as MEMS, and an electrochromic material Many methods have been proposed. These are classified and arranged in detail in Non-Patent Document 1.

These electronic papers have a pixel structure for displaying an image, and image display is controlled by controlling an applied voltage for each pixel. Therefore, a panel module in which a scanning electrode driving circuit and a data electrode driving circuit are mounted on a passive or active matrix panel in which scanning electrodes and data electrodes are connected in a matrix is required.
These drive circuit units are expensive to manufacture. Particularly, in the active type, a TFT is required for each pixel, so that the drive circuit occupies much of the cost of electronic paper. In addition, since it has a pixel structure, it is not easy to display a high-definition image with a high-density pixel structure, and more complicated drive circuits and many pixel structures are required for high-definition image display. Increase.
In particular, in the passive type, it is difficult to display a high-definition image due to the problem of crosstalk between pixels.
As described above, electronic paper is expected as an alternative technique to hard copy on paper, but it has been a problem to achieve both low manufacturing cost and high density, and has not yet been widely spread.

On the other hand, Patent Documents 1 to 5 propose methods for image display and image switching that do not have the pixel structure as described above and do not require a drive circuit and a matrix panel.
Patent Document 1 proposes a printing apparatus that forms an image by energizing a printing film containing an electrochromic material through a drawing tool having an electrode and an electrolyte part. Examples of the drawing tool include a pen type having an electrode at the tip or a plurality of dots arranged densely.
In Patent Document 2 and Patent Document 3, an electrochromic material whose optical characteristics are changed by a localized electric field and a display medium using the same are proposed. Further, in the embodiment, an electrode array is interposed between the display medium and the display medium. A method for forming an image by applying an electric field is shown.
Patent Documents 4 and 5 show an electrophoretic display medium and an image forming apparatus for forming an image on the electrophoretic display medium. In these, the display medium has matrix-shaped electrodes, but has a drive circuit. First, a system for forming an image by applying a voltage from an image forming apparatus via a plurality of electrodes has been proposed.

In the methods proposed in Patent Documents 1 to 5, the display medium does not require a pixel structure or a matrix panel, or does not require a driving circuit, so that it is overwhelmingly cheaper than conventional electronic paper. Thus, it is possible to manufacture a display medium, and it can be expected to be used as a substitute for paper.
However, since these display media or image forming apparatuses are based on the premise that they display images by rewriting many times, the display by the mechanical contact between the electrode section of the image forming apparatus and the display medium. Damage such as media wear and scratches becomes a problem.
In particular, when image formation is performed at high speed, damage due to mechanical contact between the electrode portion and the medium becomes more serious and becomes a serious problem.
In addition, in order to achieve the formation of a high-definition image, it is necessary to make the contact electrodes of the image forming apparatus finer and higher in density, which makes it difficult to form and maintain such electrodes, There is also a risk that damage to the electrodes of the forming apparatus will be significant.

  The present invention has been made in view of such circumstances, and is capable of forming a high-definition image on an inexpensive display medium that does not have a matrix panel and a driving circuit, and also displays by mechanical contact during image formation. The main purpose of the present invention is to provide an image forming apparatus and an image forming method that can prevent damage to the medium, maintain good image formation over a long period of time, and sufficiently utilize the advantages of a low-cost display medium. .

  In order to achieve the above object, according to a first aspect of the present invention, there is provided an image forming apparatus for forming an image on a display medium having an electrochromic layer and rewritable by application of a voltage. A display head supporting and conveying means for supporting the display medium and temporarily forming a bridge of a liquid column made of the conductive liquid between the nozzle and the nozzle; Voltage application means for applying a voltage between the nozzle and an electrode installed in or on the surface of the display medium is provided.

A second aspect of the present invention is the image forming apparatus according to the first aspect, further comprising an image erasing unit that applies a predetermined voltage to the entire surface of the display medium.
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the image erasing unit includes an electrolyte solution supply unit that supplies an electrolyte solution to the surface of the display medium on which an image is formed, and the display medium. A conductive member abutting on the surface, and voltage applying means for applying a voltage between the conductive member and an electrode of the display medium are provided.
According to a fourth aspect of the present invention, in the image forming apparatus according to the second aspect, the image erasing unit has an electrode layer and a solid electrolyte layer in order toward the radially outer side and abuts against the surface of the display medium. And a voltage applying means for applying a voltage between the electrode layer of the erasing roller and the electrode of the display medium.

According to a fifth aspect of the present invention, in the image forming apparatus according to the third or fourth aspect, the conductive member or the erasing roller also serves as a part of the display medium supporting and conveying unit.
A sixth aspect of the present invention is the image forming apparatus according to any one of the first to fifth aspects, further comprising a cleaning unit that removes the conductive liquid ejected to the display medium from the display medium. It is characterized by that.
According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the recording head uses colored ink in addition to the first recording head that discharges the conductive liquid. It has the 2nd recording head which discharges, It is characterized by the above-mentioned.

  According to an eighth aspect of the present invention, there is provided a method for forming an image on a display medium having an electrochromic layer and rewritable by application of a voltage, wherein a conductive liquid is applied to a predetermined position of the display medium from a recording head having a nozzle. Discharging and temporarily forming a bridge by a liquid column between the nozzle and the display medium, and applying a voltage between the nozzle and the display medium to energize the liquid column Thus, an electrochemical reaction is caused in the electrochromic layer of the display medium to form an image.

According to the present invention, an image can be formed on a display medium having an electrochromic layer using a conductive liquid ejected from a recording head equivalent to a recording head used in a conventional ink jet printer. An image can be formed on a display medium having a very simple configuration on an electronic paper having a conventional matrix panel and a driving circuit by using a conventional recording head configuration, and cost reduction can be realized.
Unlike conventional ones, when the display medium is energized, the electrodes are not brought into direct contact with each other, so that damage due to mechanical contact can be suppressed, and an increase in cost due to replacement of parts due to damage can be avoided.
Since the head and the recording control method used in the existing ink jet printer can be diverted, the apparatus can be manufactured at a lower cost.
When the image erasing unit is provided, it is possible to perform all of image formation, erasure, and rewriting. For example, the user inserts a used image-formed display medium into the image apparatus of the present invention to display a new image. It becomes possible to make it.
In the case of having the cleaning means, it is possible to eliminate discomfort due to a wet feeling or a sticky feeling.
In addition to image formation on a rewritable display medium, it is also possible to form an image on a normal recording sheet. Accordingly, it is possible to provide an image forming apparatus that allows the user to arbitrarily select an output method.

1 is a schematic diagram illustrating the principle of image formation of an image forming apparatus according to a first embodiment of the present invention. It is a control block diagram. It is a graph which shows the result of having measured the electric current which flows between a nozzle plate and the transparent electrode layer of a display medium, changing a gap. It is a fragmentary perspective view which shows the structure of a display medium. It is a fragmentary perspective view which shows the other structural example of a display medium. It is a figure which shows an example of an image erasing means. It is a figure which shows the other example of an image erasing means. FIG. 3 is a perspective view illustrating a main part of the image forming apparatus. 1 is a diagram illustrating an overall configuration of an image forming apparatus. FIG. 6 is a diagram viewed from the ejection surface side of a recording head in a second embodiment. FIG. 4 is an overall configuration diagram of an image forming apparatus according to a second embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
First, a first embodiment will be described with reference to FIGS. FIG. 1 schematically shows the principle of image formation according to the present invention (voltage application method via a fluid).
As shown in FIG. 1A, the recording head 10 includes a nozzle plate 12 on which minute nozzles 11 are formed, a liquid chamber 13, a conductive liquid 14 accommodated in the liquid chamber 13, and a liquid ejection unit. Piezoelectric element 15 (see FIG. 2).
A display medium 16 is provided facing the nozzle surface (nozzle plate 12) of the recording head 10. The display medium 16 includes a support 17 having a light scattering property, a transparent electrode layer 18, an electrochromic layer 19 made of an electrochromic material, and the like.
A predetermined voltage is applied by the power source 20 between the nozzle plate 12 or the liquid chamber 13 of the recording head 10 and the transparent electrode layer 18.
In such a configuration, an image is formed by ejecting the conductive liquid 14 from the recording head 10 to the display medium 16.

Since the recording head 10 simply replaces the ink with the conductive liquid 14, it is possible to use a recording head equivalent to that used in a normal ink jet printer.
Here, the nozzle plate 12 is used as an electrode, and in this case, the nozzle plate 12 preferably has high conductivity. In this embodiment, a recording head (commercially available inkjet printer GX5000, manufactured by Ricoh) is used. used.
As shown in FIG. 1B, the conductive liquid 14 ejected from the recording head 10 temporarily forms a bridge 21 made of a liquid column between the surface of the display medium 16 and the nozzle plate 12. The electrochromic layer 19 is energized through the liquid column 21, and a change in optical characteristics (electrochemical reaction; hereinafter simply referred to as “coloring”) is induced in a minute region of the electrochromic layer 19. , Minute dots are formed.
By repeating this many times while changing the relative position of the recording head 10 and the display medium 16, an image is formed.

  As shown in FIG. 2, the recording head 10 is controlled by a control means 22 as a microcomputer. The control means 22 controls the piezoelectric element 15 via the head drive circuit 23. In response to a voltage pulse applied to the piezoelectric element 15, the conductive liquid 14 is ejected from the nozzle 11, is deposited on the display medium 16, and a voltage is applied to the electrochromic layer 19, thereby forming an image. .

FIG. 3 shows the result of measuring the value of the current flowing between the nozzle plate 12 and the transparent electrode layer 18 of the display medium 16 through the liquid column of the conductive liquid 14 discharged from the recording head 10. Here, a 10 wt% aqueous sodium chloride solution (conductivity 11.1 S / m) was used as the conductive liquid 14, and the voltage applied by the power source 20 was 30V.
Since the current that can be passed and the total charge amount can be controlled by the gap distance between the display medium 16 and the nozzle plate 12, the applied voltage, and the conductivity of the conductive liquid 14, these may be adjusted as appropriate.
For example, when the conductivity of the conductive liquid 14 is 11.1 S / m and a voltage of 300 V to 500 V is applied with a gap of 100 μm, the amount of energized charge is about 10 to 20 nC. Since the cross-sectional area when the liquid column is deposited is about 1000 μm ^2, it is possible to apply an electric charge of 1 to ² mC / cm ² to the electrochromic layer 19 by a single liquid discharge.
This is a charge amount that can color a general electrochromic material (for example, see Non-Patent Document 2).
Under the condition that the amount of charge necessary for coloring is insufficient, it is also possible to take a means for increasing the total amount of charge and coloring by discharging the conductive liquid 14 several times at substantially the same location and conducting electricity. .

As described above, according to the present invention, since a voltage is applied by forming a bridge made of a conductive liquid, although it is a physical or mechanical contact with the surface of the display medium 16, what is in contact is a liquid. Therefore, there is almost no risk of damaging the surface of the display medium 16 as compared with a conventional method in which electrodes as rigid bodies are brought into contact with each other.
In addition, although there is a concern about damage on the electrode side in the past (particularly noticeable in the case of high definition), in the present invention, the conductive liquid 14 as a consumable serves as a contact electrode, so the recording head 10 side No damage will occur.

Next, the detail regarding each member is demonstrated.
As the liquid ejecting means used in the recording head 10, a pressure applying means for ejecting liquid by applying pressure to the liquid chamber 13, a heating means for ejecting liquid by film boiling by heating, or the like is used. Is possible.
In the present embodiment, as described above, the piezoelectric element 15 is used as the pressure applying means. The voltage applied to the piezoelectric element 15 is controlled by the head drive circuit 23, and it is possible to arbitrarily control on / off of liquid ejection.

A variety of conductive liquids can be used. In addition to the alkali metal salt aqueous solution such as the sodium chloride aqueous solution described above, an inorganic salt dissolved in an organic polar solvent such as propylene carbonate, Various liquid electrolytes such as an ionic liquid or a salt dissolved in an ionic liquid, an alkaline aqueous solution, and an acidic aqueous solution can be used.
In addition to the above-mentioned liquid electrolyte, the conductive liquid is added with a surfactant to lower the surface tension and a polymer to increase the viscosity of the liquid in order to increase the liquid column formation time and extend the energization time. May be. The conductive liquid is preferably colorless so as not to affect the appearance after image formation.

The electrochromic material used for the display medium 16 is a generic term for electrochromism, that is, a material that reversibly changes its optical properties by electrical energy. For example, as summarized in Non-Patent Document 3, A metal oxide material such as tungsten oxide, an organic material such as heptyl viologen, or a metal complex such as Prussian blue can be used.
The electrochromic material may be appropriately selected from these according to the use and color. In this embodiment, tungsten oxide is used as the electrochromic material.
As the transparent electrode layer 18 used for the display medium 16, indium tin oxide generally used as a transparent electrode can be used. The surface of the transparent electrode layer is preferably exposed at the edge of the display medium in order to apply a voltage.
As the support 17, various materials such as a polymer having a light scattering property, a glass or metal coated with an inorganic or polymer scatterer, or paper can be used.

Another embodiment of the configuration of the display medium 16 is shown in FIGS. In the display medium 16 </ b> A shown in FIG. 4, the one composed of the electrode layer 24, the light scattering layer 25, and the electrochromic layer 19 on the support 17 is shown.
In this case, it is not necessary to use a transparent electrode as the electrode layer 24, and a metal such as aluminum, silver, or platinum can be used. The light scattering layer 25 needs to be insulative but not completely insulating. For this purpose, for example, a thin layer of titanium oxide fine particles is suitable.
In the display medium 16B shown in FIG. 5, a transparent electrode layer 18, an electrochromic layer 19, a solid electrolyte layer 26, and a transparent electrode layer 27 having a pixel structure are formed on a support 7.
As the solid electrolyte layer 26, a polymer solid electrolyte in which an inorganic salt is mixed with polyethylene oxide can be used. Since the transparent electrode layer 27 has a pixel structure, even if there is a slight misalignment in the liquid ejected from the recording head 10, a change in the position of the voltage applied to the electrochromic layer 19, that is, a color misalignment is not caused. Few.

Next, a method for erasing and initializing an already written image (image erasing means) will be described. In order to erase the image on the display medium 16, a voltage may be applied between the electrode and the entire display medium.
For example, as shown in FIG. 6, after applying the electrolyte solution to the surface of the display medium 16 on which the image is written by the electrolyte solution applying means 30 including the electrolyte solution supplying means 28 and the blade 29, the voltage applying means is used. By conveying while pressing a conductive roller 32 as a conductive member to which a predetermined voltage is applied by a power supply 31, it is possible to erase an image on the entire surface of the display medium. An image erasing unit 33 is constituted by the electrolyte solution supply unit 28, the conductive roller 32, and the power source 31.
In FIG. 6, reference numeral 34 denotes a transport roller that faces the electrolyte solution applying means 30, and 35 denotes a transport roller that faces the conductive roller 32.
FIG. 7 shows another example of the image erasing means. The image erasing unit 36 includes an erasing roller 37 and a power source 38 as a voltage applying unit. The erasing roller 37 has an electrode layer 39 and a solid electrolyte layer 40 provided outside the electrode layer. A predetermined voltage is applied between the electrode layer 39 and the transparent electrode layer of the display medium 16. When passing through the erasing roller 37, the image on the display medium 16 is erased.
The power supply 38 need not always be applied with a voltage during image formation. For example, a method of applying a voltage only when a user designates an image erasing mode during image formation is also conceivable. In addition, here, the erasing roller 37 has the solid electrolyte layer 40, but instead, a means for applying the liquid electrolyte layer to the electrode layer 39 may be provided.
In FIG. 7, reference numeral 40 denotes a conveyance roller.

FIG. 8 shows a main part of the image forming apparatus according to the present embodiment.
The recording head 10 can be moved by a carriage 41 in a sub-scanning direction orthogonal to the conveyance direction of the display medium 16. The liquid chamber 13 of the recording head 10 is appropriately supplemented with the conductive liquid 14 from the liquid tank 42.
The display medium 16 is conveyed in the arrow direction at a predetermined speed by the display medium support conveyance means 43. The display medium support / conveyance means 43 includes a conveyance roller pair 44 that sandwiches and conveys the display medium 16, an opposing roller 45 that faces the recording head 10, and the like.
The display medium support conveyance means 43 conveys the display medium 16 and maintains a gap between the nozzle plate 12 of the recording head 10 and the surface of the display medium 16 at an appropriate distance.

In order to maintain the gap distance, the display medium support transport means 43 has a gap control system. Specifically, a position sensor 50 (see FIG. 2) that calculates the thickness of the display medium 16 from the mechanical positional relationship of the conveying roller pair 44, and a counter roller that displaces the counter roller 45 in accordance with the output of the position sensor 50. A drive mechanism 51 (see FIG. 2) is provided. Control according to the output of the position sensor 50 is performed by the control means 22.
The gap control system is not limited to this, and an optical distance sensor (reflection type sensor) may be provided in the recording head 10 or the carriage 41 instead of the position sensor 50.
As another method, a gap measuring unit that measures the amount of current flowing by the power source 20 instead of the position sensor 50 and calculates the gap from the result may be provided.
In addition to these, the display medium support / conveyance means 43 may include a system for adsorbing the display medium as necessary.

A predetermined voltage can be applied between the nozzle surface of the recording head 10 and the transparent electrode layer 18 of the display medium 16 by a power source 20 as voltage applying means. The power source 20 has means for taking an electrical contact from the transparent electrode layer 18 of the display medium 16. This can be achieved, for example, by a method using a leaf spring type contact electrode from a transparent electrode layer exposed on the end plate of the display medium.
The voltage application means may be applied with a voltage at the time of image formation, and it is conceivable to change the voltage to be applied according to the image to be formed.
In accordance with the conveyance of the display medium 16 by the display medium support conveyance means 43 and the movement of the carriage 41, the discharge of the conductive liquid 14 from the recording head 10 is controlled, and the electrochromic layer 19 on the display medium 16 is energized. To form an image.
The principle of coloring the electrochromic layer 19 is as already described.
As described above, image formation can be performed on the rewritable display medium 16 including the electrochromic layer 19.

The configuration shown in FIG. 8 may include a cleaning unit 55 (see FIG. 9) that removes the conductive liquid 14 discharged onto the display medium 16 after image formation. This is because the conductive liquid remains on the surface of the display medium 16 after the image formation, which may cause the user to feel uncomfortable due to a wet feeling or a sticky feeling.
As the cleaning means 55, for example, a blade-like material made of rubber such as silicon or urethane may be pressed against the surface of the display medium 16 to scrape the liquid.
As a different form of the cleaning means 55, it is possible to adopt a configuration in which a roller or a blade having a liquid absorbing property is pressed.

FIG. 9 shows the overall configuration of the image forming apparatus according to the present embodiment.
As the image erasing means, the image erasing means 36 shown in FIG. 7 is adopted. A dotted line arrow in the drawing indicates a conveyance path of the display medium 16. A plurality of display media 16 are held in the paper feed tray 56 and are taken out and transported one by one by the display media support and transport means 43 as needed.
The display medium 16 passes through the image erasing means 36 so that the image is erased as necessary. The image erasing means 36 is the same as that shown in FIG. 7, and whether or not voltage application is required can be designated at the same time when the user issues an image formation instruction.
An erasing roller 37 of the image erasing unit 36 and a conveying roller 40 facing the erasing roller 37 have a part of the conveying function of the display medium support conveying unit 43. That is, the transport roller that is a part of the display medium support transport unit 43 is also used as the image erasing unit. Of course, an image erasing unit may be provided separately from the conveying roller.
An optical sensor (not shown) may be installed in front of the image erasing means 36 to detect the presence or absence of an image already formed by optical detection, and to determine the presence or absence of voltage application from the result. is there.
The display medium 16 transported by the display medium support transport means 43 forms an image by discharging the conductive liquid of the recording head 10 and applying a voltage from the power source 20. After the conductive liquid 14 is removed by the cleaning means 55, The paper is discharged onto the paper discharge tray 57.

Based on FIG.10 and FIG.11, 2nd Embodiment is described. In addition, the same part as the said embodiment is shown with the same code | symbol, and unless it was especially required, the description on the structure and function which were already performed is abbreviate | omitted, and only the principal part is demonstrated.
As shown in FIG. 10, in addition to the first recording head 61 (corresponding to the recording head 10) that discharges the conductive liquid, the recording head 60 in this embodiment has a second recording head 62 that discharges colored ink. have. In other words, the recording head 60 is a composite head of a recording head for applying a voltage to the electrochromic layer 19 and a recording head of a conventional inkjet printer.
FIG. 10 shows the recording head 60 as viewed from the nozzle surface side. The first recording head 61 has a nozzle row for discharging a conductive liquid, and the second recording head 62 has four liquid discharge nozzle rows. As shown in the drawing, each of them can discharge ink colored yellow (Y), magenta (M), cyan (C), and black (K).
In such a configuration, in addition to the use of forming an image on the rewritable display medium having the electrochromic material layer described above, it is possible to form an image with colored ink on ordinary paper.

FIG. 11 shows the overall configuration of the image forming apparatus according to the present embodiment.
This image forming apparatus has a second paper feed tray 63 on which ordinary recording paper P is mounted. The recording paper P held in the paper feed tray 63 is transported by the display medium support transport means 43, and after the image is formed by the color ink ejection of the recording head 60, the paper is ejected onto the paper ejection tray 57.
In this case, the cleaning means 55 does not function.
The user can arbitrarily select whether to form an image on the display medium 16 or to form an image on the recording paper P using an operation panel (not shown).
The power source 20 is in a driving state and applies a voltage only when an image formation on the display medium 16 is instructed. Further, the display medium support / conveyance means 43 determines whether the nozzle surface of the recording head 60 and the surface of the display medium 16 or the recording medium P are in accordance with whether the image formation on the display medium 16 or the image formation on the recording paper P is instructed. It is possible to change the control value of the gap distance.
The liquid tank 65 holds conductive liquid and colored ink, respectively, and supplies liquid to the recording head 60 as necessary.
With the configuration described above, the image forming apparatus according to the present embodiment can perform both image formation on a display medium including an electrochromic material layer and image formation on a recording sheet.

DESCRIPTION OF SYMBOLS 11 Nozzle 10 Recording head 16 Display medium 19 Electrochromic layer 20 Power supply as a voltage application means 21 Bridge 30 Electrolyte supply means 31 Voltage application means 32 Conductive rollers 33 and 36 as conductive members Image erasure means 37 Erase roller 38 Voltage Application means 39 Electrode layer 40 Solid electrolyte layer 43 Display medium support transport means 55 Cleaning means 61 First recording head 62 Second recording head

JP 2007-163758 A JP 2003-98555 A JP 2003-287775 A JP 2004-317648 A JP 2004-317550 A

“Electronic Paper”, Tokyo Denki University Press (2008) “Electrochromic display”, industrial books p. 85 (1991) “Electrochromic display”, industrial books p. 28 (1991)

Claims (8)

In an image forming apparatus that has an electrochromic layer and forms an image on a rewritable display medium by applying a voltage,
A recording head including a nozzle for discharging a conductive liquid;
A display medium supporting and conveying means for supporting the display medium and temporarily forming a bridge of a liquid column made of the conductive liquid between the display medium and the nozzle;
An image forming apparatus, comprising: a voltage applying unit configured to apply a voltage between the nozzle and an electrode installed in or on the surface of the display medium. The image forming apparatus according to claim 1.
An image forming apparatus comprising image erasing means for applying a predetermined voltage to the entire surface of the display medium. The image forming apparatus according to claim 2.
The image erasing unit includes an electrolyte solution supply unit that supplies an electrolyte solution to the surface of the display medium on which an image is formed, a conductive member that contacts the surface of the display medium, and the conductive member and the display medium. An image forming apparatus comprising: a voltage applying unit that applies a voltage between the electrode and the electrode. The image forming apparatus according to claim 2.
The image erasing means comprises an erasing roller having an electrode layer and a solid electrolyte layer in order toward the outer side in the radial direction and in contact with the surface of the display medium; the electrode layer of the erasing roller; and an electrode of the display medium An image forming apparatus comprising voltage applying means for applying a voltage therebetween. The image forming apparatus according to claim 3 or 4, wherein:
The image forming apparatus, wherein the conductive member or the erasing roller also serves as a part of the display medium supporting and conveying unit. The image forming apparatus according to claim 1,
An image forming apparatus, comprising: a cleaning unit that removes the conductive liquid discharged to the display medium from the display medium. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the recording head includes a second recording head for discharging colored ink in addition to the first recording head for discharging the conductive liquid. In a method of forming an image on a display medium having an electrochromic layer and rewritable by application of a voltage,
A liquid having conductivity is discharged from a recording head having a nozzle to a predetermined position of the display medium, and a bridge formed by a liquid column is temporarily formed between the nozzle and the display medium, and the nozzle and the display An image forming method, wherein an image is formed by applying a voltage to a medium to cause an electrochemical reaction in the electrochromic layer of the display medium by energization through the liquid column.

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