JP2012037769A - Image rewriting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image rewriting device that rewrites an image of a display medium for holding charged particles, and obtains an excellent image quality without generating abnormal discharge between the display medium and the device before rewriting the image.SOLUTION: The image rewriting device rewrites an image of an electronic paper with a nip section between a polyimide belt 300 and a counter electrode roller 400. In the image rewriting device, a neutralization head 201 for changing surface potential of the electronic paper 1000 is arranged at upstream in conveyance direction of the electronic paper 1000, and a neutralization head 200 for changing surface potential of the polyimide belt 300 is arranged at upstream in moving direction of the polyimide belt 300. An absolute value of the difference of the surface potential of the electronic paper 1000 and the surface potential of the polyimide belt 300 is made smaller than absolute values of their discharge starting voltages just before the nip section.

Description

  The present invention relates to an image rewriting apparatus that rewrites an image on a display medium having charged particles.

  In recent years, electronic paper has been known as a display medium that changes an image along with movement of charged particles held inside. An image rewriting apparatus that rewrites an image on an electronic paper by generating an electric field is known. As the principle of electronic paper, a microcapsule type electric permanent system, a toner display system, a twist ball system, an electronic powder fluid system, and the like are known (Non-Patent Document 1). The image is rewritten by moving.

  As electronic paper, one having a drive circuit such as a passive matrix or an active matrix for applying a voltage to each electrode in the electronic paper is known (Patent Document 1), but has an electrode and a drive circuit. There is no known e-paper. Therefore, Patent Document 2 discloses an electronic paper image in which an electrode head and a counter electrode roller are brought close to an electronic paper having no electrode and a drive circuit, and a voltage is applied between the electrode head and the counter electrode roller. Has been disclosed. Patent Document 3 discloses a method of rewriting an image with an electrode head, a discharge electrode, or a charged drum facing an electronic paper having a solid electrode.

JP 2008-191324 A JP 2004-294891 A JP 2008-176337 A

Latest Trends in Electronic Paper 2007, Journal of Imaging Society of Japan 46, p372-p384 (2007: Akira Suzuki)

  However, the conventional image rewriting apparatus has a problem that abnormal electric discharge occurs between the electronic paper in a charged state and each device before image rewriting, which leads to an image defect. Accordingly, the present invention provides an image rewriting apparatus that rewrites an image on a display medium that holds charged particles, and that can obtain good image quality without causing abnormal discharge between the display medium and the apparatus before rewriting the image. An object is to provide a rewriting device.

In order to achieve the above object, the present invention provides:
A movable dielectric film; an electrode head in contact with the dielectric film; and an opposing roller disposed on the opposite side of the electrode head across the dielectric film, the electrode With a voltage applied to the head, a display medium that holds charged particles in a movable manner is passed through the nip portion between the dielectric film and the opposing roller in the same direction as the movement direction of the dielectric film. In the image rewritable apparatus capable of rewriting an image on a display medium in the nip portion, a first potential change member that changes a surface potential of the display medium upstream of the nip portion in the transport direction of the display medium, and the dielectric A second potential change member that changes the surface potential of the dielectric film upstream of the nip portion in the moving direction of the film; Thus, the display medium after passing through the first potential change member is transported to the nip portion so as to gradually approach the dielectric film after passing through the second potential change member. And the surface of the display medium on the upstream side of the nip portion in the conveyance direction of the display medium and the movement direction of the dielectric film and on the downstream side of the first potential change member and the second potential change member. The first potential change member such that the absolute value of the potential difference between the potential and the surface potential of the dielectric film is smaller than the absolute value of the discharge start voltage between the display medium and the dielectric film immediately before the nip portion. And the second potential change member changes the surface potential of the display medium and the dielectric film, respectively.

Also,
A film member provided movably and having a dielectric layer on at least one surface thereof; an electrode head in contact with the film member and provided with a heating resistor; and the film member. An opposing roller disposed on the opposite side of the electrode head, and applying a voltage to the electrode head, energizing the heating resistor to heat the heating resistor, and the film member With the dielectric layer coming to the opposing roller side, a display medium that holds charged particles inside is passed through the nip portion between the film member and the opposing roller in the same direction as the moving direction of the film member. Thus, in the image rewriting device capable of rewriting the image of the display medium in the nip portion, the display medium surface is positioned upstream of the nip portion in the conveyance direction of the display medium. A first potential changing member that changes the potential; and a second potential changing member that changes the surface potential of the film member upstream of the nip portion in the moving direction of the film member. The display medium after passing through the first potential change member is conveyed to the nip portion so as to gradually approach the film member after passing through the second potential change member, and the nip The surface potential of the display medium and the film member on the upstream side in the conveyance direction of the display medium and the movement direction of the film member relative to the portion, and on the downstream side of the first potential change member and the second potential change member The first potential change so that the absolute value of the potential difference between the surface potentials of the first and second films is smaller than the absolute value of the discharge start voltage between the display medium and the film member immediately before the nip portion. Wherein the member and the second potential change members are respectively change the surface potential of the film member and the display medium.

  According to the present invention, in an image rewriting apparatus that rewrites an image of a display medium that holds charged particles, it is possible to obtain good image quality without causing abnormal discharge between the display medium and the apparatus before rewriting the image. An image rewriting device can be provided.

1 is a schematic configuration diagram of an image rewriting device according to a first embodiment. The schematic block diagram of the image rewriting apparatus which concerns on 2nd Embodiment. FIG. 10 is a schematic configuration diagram of an image rewriting device according to a fourth embodiment. FIG. 10 is a schematic configuration diagram of an image rewriting device according to a fifth embodiment. 1 is a schematic cross-sectional view of electronic paper. 1 is a schematic cross-sectional view of electronic paper. 1 is a schematic cross-sectional view of electronic paper. 1 is a schematic cross-sectional view of electronic paper. The schematic block diagram of the electrode head in 1st Embodiment. The schematic block diagram of the electrode head in 1st Embodiment. The schematic block diagram of the electrode head in 5th Embodiment. The figure for demonstrating the process of image rewriting.

[First embodiment]
(1-1: Schematic configuration of image rewriting device)
With reference to FIG. 1, a schematic configuration of an image rewriting apparatus according to the present embodiment will be described. The image rewriting apparatus is provided with an endless polyimide belt 300 (dielectric film) that is movably provided, and an electrode head 104 that is in contact with the inner surface of the polyimide belt 300. For the polyimide belt 300, polyimide having a thickness of 0.15 mm is used. A head facing roller 400, which is a stainless steel roller having an outer diameter of 12 mm, is disposed on the opposite side of the electrode head 104 across the polyimide belt 300, and the head facing roller 400 is grounded. Here, a polyimide film is used as the dielectric film, but a material other than polyimide may be used as long as it is a dielectric, and for example, polyethylene may be used. Here, the dielectric means a substance that generates electric polarization when an electric field is applied. In the present embodiment, an electric field is applied at the time of image rewriting as will be described later, so that an electric current is generated in the polyimide belt 300 as a dielectric film. It is comprised so that polarization may arise.

  The electrode head 104 is supported by the support 102 that is urged in the direction of the head facing roller 400 by the pressure spring 103, whereby the polyimide belt 300 is pressed in the direction of the head facing roller 400, and the nip is caused by both. The part is formed. Hereinafter, when simply described as “nip part”, this nip part is indicated. The electrode head 104, the support 102, and the pressure spring 103 are unitized as a writing head unit 100, and the electrode head 104 is electrically connected to the voltage application unit 650.

  The polyimide belt 300 is stretched so as to be movable by conveying platen rollers 600 to 605 driven by a driving source (not shown). The conveyance platen rollers 600 to 605 are stainless steel rollers having an outer diameter of 8 mm, and the conveyance platen rollers 600, 603, and 605 are grounded.

  Further, in the transport direction of the electronic paper 1000, a static elimination head 201 (first potential change member) is provided as a static elimination member for neutralizing the electronic paper 1000 on the upstream side of the nip portion in the transport direction. Further, in the movement direction of the polyimide belt 300, a static elimination head 200 (second potential change member) is provided as a static elimination member for neutralizing the polyimide belt 300 upstream of the nip portion in the movement direction. The static elimination heads 200 and 201 can generate both positive and negative ions, and a control unit (not shown) supplies positive ions or negative ions depending on the charged state of the surface of the static elimination object. Can be appropriately selected.

  By providing the static elimination heads 200 and 201 in this way, the areas of the electronic paper 1000 and the polyimide belt 300 that have been neutralized enter the nip portion, and both come into contact with each other for the first time in the nip portion. Although the case where the static elimination heads 200 and 201 are used as the static elimination member is described here, the configuration of the static elimination member is not limited to this, and a static elimination brush or the like may be used.

In rewriting the image of the electronic paper 1000, the inserted electronic paper 1000 was conveyed to the nip portion by rubber conveying rollers 610 and 611 in which urethane rubber having an outer diameter of 12 mm was provided on the surface of a stainless steel core having an outer diameter of 6 mm. Thereafter, it is performed at the nip portion. In the nip portion, a voltage is applied from the voltage application unit 650 to the electrode head 104, thereby generating an electric field (discharge phenomenon) between the electrode head 104 and the head facing roller 400, thereby causing charged particles of the electronic paper 1000. The image is rewritten by moving. The electronic paper 1000 is passed through the nip portion at a constant speed and the image is rewritten from the leading end side in the transport direction. After passing through the nip portion, the electronic paper 1000 is discharged from the image rewriting device by a discharge member (not shown).

(1-2: Schematic configuration of electrode head)
The schematic configuration of the electrode head 104 will be described in more detail with reference to FIGS. As shown in FIG. 9, the electrode head 104 has a ceramic substrate 105 on which a glass layer 106 having a convex cross section is formed. An AL electrode layer 107 is formed on the surface of the glass layer 106 by a sputtering method, and the AL electrode layer 107 is processed into a predetermined pattern to form a plurality of electrodes. In the pattern processing, an insulating layer is applied before the AL electrode layer 107 is formed, the insulating layer is formed between the AL electrodes 107, and the AL electrode layers 107 are insulated from each other. Adopted. However, as a method other than this, a method of applying an insulating layer so as to cover the whole after forming the AL electrode layer 107 may be employed.

  Further, the electrode head 104 is provided with a driver 108 for selectively applying a voltage to each electrode formed by pattern processing. By electrically connecting the driver 108 and an external wiring board for inputting a driving signal from the outside, it is possible to apply a voltage from the voltage applying unit 650 to each electrode. The polarity and magnitude of the voltage applied to each electrode can be set for each electrode by a control unit (not shown).

  As shown in FIG. 10, a plurality of electrodes formed by patterning the AL electrode layer 107 are arranged in a direction orthogonal to the electronic paper transport direction (lower left to upper right in the figure). Although not shown in FIG. 10, three pressure springs 103 for urging the support body 102 that supports the electrode head 104 are arranged along the longitudinal direction of the ceramic substrate 105, and a total of 21 N push springs are arranged. The electrode head 104 is pressed by pressure.

(1-3: Schematic configuration of electronic paper)
The electronic paper 1000 will be described with reference to FIGS. The electronic paper illustrated in FIG. 5 includes a sheet-like base material layer 1010, an image forming layer 1020, and a coating layer 1030. The thickness of each layer is 200 μm for the base material layer 1010, 50 μm for the image forming layer 1020, and 40 μm for the coating layer 1030. In addition, a plurality of transparent microcapsules 1040 are arranged in the image forming layer 1020, and these microcapsules 1040 are fixed in the electronic paper 1000 by a binder resin. Here, polyvinyl alcohol or the like is used as the binder resin. Note that none of the electronic papers 1000 has a conductive layer formed on the surface in contact with the dielectric film.

  In each microcapsule 1040, black particles 1042 and white particles 1041 as charged particles and an insulating liquid 1043 are sealed. The black particles 1042 are negatively charged and the white particles 1041 are positively charged. Thus, the color of the charged particles and the charged polarity are associated with each other (however, the combination of the color and the charged polarity is related to this). Not limited). Further, both the black particles 1042 and the white particles 1041 can move in the microcapsule 1040. That is, it can be said that the electronic paper 1000 holds the charged particles in a movable manner.

  There are various forms of the image forming layer 1020. Here, an image rewriting method for rewriting an image on the electronic paper 1000 of the “microcapsule type electrophoresis method” will be described first.

When rewriting an image, a voltage is applied to each electrode of the electrode head 104, and an electric field is generated in the vertical direction in FIG. As a result, the black particles 1042 and the white particles 1041 move in opposite directions (electrophoresis) in the microcapsule by the force received from the electric field. For example, when an electric field is applied so that the upper direction (coating layer 1030 side) in the figure is positive and the lower direction (base material layer 1010 side) is negative, the white particles 1041 move downward, and the black particles 1042 Moves upward. That is, according to this method, the polarity of the voltage applied to each electrode head 104 is set for each electrode based on image information, so that white and black can be switched in units of microcapsules. The image pattern can be displayed. In FIG. 5, an electric field is applied such that only a part of the coating layer 1030 side is negative and the white particles 1041 are on the coating layer 1030 side.

  With reference to FIG. 6, the “twist ball method” image rewriting method will be described. In this system, instead of the above-described black particles and white particles, a twist ball having a part having a positive charging characteristic 1323 (black part) and a part having a negative charging characteristic 1322 (white part) in one particle. A feature is that a plurality of 1321 is provided in the image forming layer 1320. In the figure, 1000 represents electronic paper, 1310 represents a sheet-like base material layer, and 1330 represents a coating layer. According to this, it is possible to rewrite the image by setting the polarity of the voltage applied to each electrode head 104 based on the image information and moving (rotating) the twist ball 1321 accordingly.

  With reference to FIG. 7, the “toner display method” image rewriting method will be described. The electronic paper 1000 includes a sheet-like base material layer 1410, an image forming layer 1420, a coating layer 1430, and a charge transport layer CTL 1470. The thickness of each layer is 200 μm for the base material layer 1410, 50 μm for the image forming layer 1020, 40 μm for the coating layer 1430, and 15 μm for the charge transport layer CTL 1470. The image forming layer 1420 contains black toner 1421 and white toner 1422 having a diameter of about 8 μm.

  In the “toner display method”, the voltage polarity applied to the electrodes of the electrode head 104 is set for each electrode based on image information, and the black toner 1421 and the white toner 1422 are moved (rotated) to rewrite the image. Can do. Although not shown, as an associated image rewriting method, there is an “electronic powder fluid method” image rewriting method. In this method, instead of the black toner 1421 and the white toner 1422, particles having fluidity close to a liquid called an electronic powder fluid are used.

  In the present embodiment, the case where the “microcapsule type electrophoresis method” is adopted is described. However, the image rewriting device according to the present invention is compatible with all the image rewriting methods described above. Therefore, the image rewriting apparatus according to the present embodiment can also be applied to electronic paper having a simple configuration that does not include a drive circuit or an electrode.

(1-4: Image rewriting process)
With reference to FIG. 1, an image rewriting process of the electronic paper 1000 will be described. First, using the static elimination heads 200 and 201, the surface potential of the electronic paper 1000 and the surface potential of the polyimide belt 300 are neutralized to about 0V. The areas of the electronic paper 1000 and the polyimide belt 300 that have been neutralized become closer to each other as they approach the nip, so that they first contact each other at the nip. That is, the electronic paper 1000 after passing through the static elimination head 201 is conveyed to the nip portion in the same direction as the polyimide belt 300 so as to gradually approach the polyimide belt 300 after passing through the static elimination head 200.

  According to this configuration, at least from the downstream side of the static elimination position to the position immediately before the nip portion, the absolute value of the potential difference between the surface potential of the electronic paper 1000 and the surface potential of the polyimide belt 300 is determined by the discharge of both at the position immediately before the nip portion. The absolute value of the starting voltage can be made smaller. Therefore, there is no possibility that discharge (abnormal discharge) occurs between the electronic paper 1000 and the polyimide belt 300 before rewriting the image at the nip portion.

  When the electronic paper 1000 is conveyed to the nip portion, a voltage is applied to the electrodes on the electrode head substrate 104, and a discharge is generated between the electronic paper 1000 and the polyimide belt 300. As a result, the charged particles in the electronic paper 1000 move, and the image is rewritten. At this time, the voltage applied to the electrode on the electrode head 104 corresponding to the non-image portion is −1000 V, and the surface potential of the electronic paper 1000 becomes −200 V due to discharge. As a result, potential distributions of −200 V and 0 V can be formed on the electronic paper 1000. The positively charged white particles in the electronic paper 1000 are attracted to this −200 V, and the image of the electronic paper 1000 is rewritten.

  When an image written previously remains on the electronic paper 1000, it is necessary to write a new image after performing an erasing process for erasing the remaining image. When performing the erasing process, +1000 V is applied to all the electrodes on the electrode head 104, and the surface potential of the electronic paper 1000 is set to + 200V. At this time, the connection direction of the voltage application unit 650 is switched, and a voltage is applied as shown by a dotted line in FIG. Thus, the negatively charged black particles on the upper side of the electronic paper 1000 move to the lower surface of the electronic paper 1000 in FIG. 1 and the initialization is completed (the entire surface of the electronic paper 1000 is displayed in black).

  As described above, in this embodiment, since the polyimide belt 300 and the electronic paper 1000 are neutralized using the static elimination heads 200 and 201, abnormal discharge does not occur between the two before the image rewriting. Therefore, in an image rewriting apparatus for rewriting an image on a display medium holding charged particles, an image rewriting apparatus capable of obtaining good image quality without causing abnormal discharge between the display medium and the apparatus before rewriting the image is provided. It becomes possible to do.

[Second Embodiment]
An image rewriting apparatus according to a second embodiment to which the present invention is applicable will be described with reference to FIG. In addition, about the structure same as 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted, and only a different point from 1st Embodiment is demonstrated here.

(2-1: Schematic configuration of image rewriting device)
The image rewriting apparatus has a writing head unit 100 similar to that of the first embodiment and a movable cylindrical film 310 (dielectric film). The writing head unit 100 is held by a holding frame 111, and the cylindrical film 310 is held by a frame 112 that is bis-coupled to the holding frame 111. The holding frame body 111 has three hole grooves in the depth direction in the drawing for holding the pressure spring 103, and presses the support body 102 at these three points. A hard steel wire is used for the pressurizing spring 103, and this makes it possible to apply a total force of 21 N at the location where the electrode head 104 is pressed against the head facing roller 400.

  The cylindrical film 310 is a polyimide film having an outer diameter of 30 mm and a thickness of 0.15 mm, and the holding frame body 111 and the frame body 112 are both formed of ABS resin. As in the first embodiment, the cylindrical film 310 can be made of a dielectric material such as polyethylene. When the electrode head 104 is urged in the direction of the head facing roller 400, a nip portion is formed by the cylindrical film 310 and the head facing roller 400. Hereinafter, when simply described as “nip part”, this nip part is indicated.

In addition, the image rewriting device is provided with a film charging roller 210 (second potential change member) and a film counter electrode roller 500 disposed to face the upstream side of the nip portion in the rotation direction of the cylindrical film 310. ing. Similarly, a charging roller 800 (first potential changing member) and a counter electrode roller 501 disposed to face the charging roller 800 are provided upstream of the nip portion in the transport direction of the electronic paper 1000. Here, the counter electrode rollers 500 and 501 were formed of SUS and had an outer diameter of 8 mm. These counter electrode rollers 500 and 501 are both connected to ground.

The film charging roller 210 and the charging roller 800 are roller chargers using a conductive elastic layer and a urethane rubber layer (outer diameter 12 mm) formed on a SUS core (outer diameter 8 mm). The surface resistance is adjusted to be 10 ⁶ Ωcm to 10 ¹⁴ Ωcm. Note that a roller charger is used here as a means for charging the cylindrical film 310 and the electronic paper 1000 before rewriting the image. However, the form of the charging means is not limited to the roller charger, and a brush Other charging means such as a charger can also be employed.

  The cylindrical film 310 is sandwiched between the film charging roller 210 and the film counter electrode roller 500, and is rotated by these rollers. Further, it is also rotated by the pressure applied by the electrode head 104 and the head facing roller 400 at the nip portion. Here, the cylindrical film 310 is prevented from being bent between the film charging roller 210 and the head facing roller 400 by rotating the head facing roller 400 quickly with respect to the film charging roller 210.

  Specifically, the peripheral speed of the head-facing roller 400 is set so that the rotational speed of the cylindrical film 310 is 100 mm / s, and the film has a peripheral speed difference with respect to the peripheral speed of the head-facing roller 400. The peripheral speed of the charging roller 210 was set to 90 mm / s. By setting in this way, it is possible to prevent the cylindrical film 310 from being bent and thereby contacting the cylindrical film 310 and the film charging roller 210.

(2-2: Image rewriting process)
The image rewriting process of the electronic paper 1000 will be described with reference to FIG. The electronic paper 1000 that has been transported from the left in the figure is transported between the charging roller 800 and the counter electrode roller 501. Here, 1400 V as an AC component, a frequency of 500 Hz, and −1000 V as a DC component are applied to the charging roller 800, whereby the surface of the electronic paper 1000 is charged to about −700 V. On the other hand, 1400 V as an AC component, a frequency of 500 Hz, and −1000 V as a DC component are also applied to the film charging roller 210, whereby the surface of the cylindrical film 310 is charged to about −700 V.

  That is, on the upstream side of the nip portion and on the downstream side of the charging roller 800 and the film charging roller 210, the absolute value of the surface potential difference between the electronic paper 1000 and the cylindrical film 310 is the discharge start voltage of both at the position immediately before the nip portion. Less than absolute value. Therefore, there is no possibility that discharge (abnormal discharge) occurs between the electronic paper 1000 and the cylindrical film 310 before entering the nip portion.

  Next, the charged electronic paper 1000 comes into contact with the cylindrical film 310 between the electrode head 104 and the head facing roller 400. At this time, since the electronic paper 1000 and the cylindrical film 310 are charged to substantially the same potential, no discharge occurs. By applying a voltage of 1000 V to the electrode corresponding to the image display portion, a discharge for image rewriting is generated in the nip portion. As a result, the surface potential of the electronic paper 1000 becomes 200 V, the charged particles in the electronic paper 1000 move, and the image is rewritten.

The image rewriting process will be described in more detail with reference to FIG. FIG. 12 shows an enlarged cross-sectional view of a nip portion formed by the electrode head 104 and the cylindrical film 310. Reference numeral 1 in the figure denotes a charge generated on the electronic paper 1000. Reference numeral 2 denotes a charge generated on the cylindrical film 310. Further, when the electrode 107 is painted black, a voltage is applied. In FIG. 12, the upper left indicates “when a voltage is applied to the electrode 107”, the lower left indicates “when a discharge occurs”, and the upper right indicates “when image rewriting is completed”.

  As described above, after the electronic paper 1000 and the cylindrical film 310 charged to −700 V are contacted, a voltage is applied to the electrode 107 in the nip, thereby generating a discharge as shown in the lower left of FIG. Thereafter, the electrons 1 and 2 on the electronic paper 1000 and the cylindrical film 310 are eliminated by this discharge, and the potential of the image portion becomes + 200V. As a result, as shown in the upper right, the negatively charged black particles in the electronic paper 1000 move downward in FIG. 10, whereby the image on the electronic paper 1000 is rewritten.

  As described above, according to the present embodiment, the electronic paper 1000 and the cylindrical film 310 are charged before rewriting an image in the nip portion, and the absolute value of the surface potential difference between the two is calculated as the absolute value of the discharge start voltage immediately before the nip portion. It can be made smaller than the value. Therefore, abnormal discharge does not occur between the two before rewriting the image. Further, since the electronic paper 1000 is forcibly charged between the charging roller 800 and the counter electrode roller 501, the previous image remaining on the electronic paper 1000 can be erased at this time. Therefore, it is not necessary to separately perform an erasing process at the nip portion, so that the image can be rewritten at high speed on the electronic paper 1000.

  As described above, in an image rewriting apparatus for rewriting an image on a display medium holding charged particles, an image rewriting apparatus capable of obtaining good image quality without causing abnormal discharge between the display medium and the apparatus before rewriting the image. It becomes possible to provide.

[Third embodiment]
An image rewriting apparatus according to a third embodiment to which the present invention is applicable will be described. In addition, about the same structure as 1st, 2nd embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted, and only a different point from 1st, 2nd embodiment is demonstrated here.

(3-1: Image rewriting process)
The configuration of the image rewriting device is the same as that described in the second embodiment. In the second embodiment, before rewriting the image of the electronic paper 1000 at the nip portion, the electronic paper 1000 and the cylindrical film 310 are each charged to about −700 V to prevent abnormal discharge.

  On the other hand, in this embodiment, the electronic paper 1000 is charged to −1100 V by applying a voltage of 2000 V as an AC component, a frequency of 500 Hz, and a voltage of −1600 V as a DC component to the charging roller 800. The cylindrical film 310 was charged to −700 V as in the second embodiment.

  In this case, in the region before the electronic paper 1000 and the cylindrical film 310 are in contact with each other at the nip portion, a potential difference of about 400 V is generated between them as an absolute value. Is sufficiently smaller than the absolute value of. Therefore, there is no possibility that abnormal discharge occurs between the electronic paper 1000 and the cylindrical film 310 before the image is rewritten in the nip portion.

Furthermore, according to this configuration, when a voltage of 600 V is applied to the electrode when a voltage is applied to the electrode corresponding to the image display portion in the nip portion, a discharge for image rewriting can be caused. That is, in the second embodiment having the same configuration, 1000 V is applied, whereas in this embodiment, when 600 V is applied, the image can be rewritten. Therefore, since the switching voltage for the electrode head 104 at the time of image rewriting can be lowered, the drive circuit for the electrode head 104 can be simplified and the cost can be reduced. Further, as in the second embodiment, it is not necessary to separately perform an erasing process, so that high-speed rewriting of an image can be performed on the electronic paper 1000.

  As described above, in an image rewriting apparatus for rewriting an image on a display medium holding charged particles, an image rewriting apparatus capable of obtaining good image quality without causing abnormal discharge between the display medium and the apparatus before rewriting the image. It becomes possible to provide.

[Fourth embodiment]
An image rewriting apparatus according to a fourth embodiment to which the present invention is applicable will be described with reference to FIGS. In addition, about the same structure as 1st-3rd embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted and only a different point from 1st-3rd embodiment is demonstrated here.

(4-1: Image rewriting process)
The image rewriting apparatus according to the present invention can rewrite an image on an electronic paper 1200 having a conductive layer instead of the electronic paper 1000 described in the first to third embodiments. First, a schematic configuration of electronic paper 1200 that can be used for the image rewriting apparatus according to the present embodiment will be described with reference to FIG.

  The electronic paper 1200 includes a sheet-like base material layer 1010, an image forming layer 1020, a coating layer 1030, and a conductive layer 1250. The thickness of each layer is 200 μm for the base material layer 1010, 50 μm for the image forming layer 1020, and 40 μm for the coating layer 1030, and the conductive layer 1250 is formed on the base material layer 1010 by vapor deposition. The configuration of the microcapsule 1040 is the same as that described in the first embodiment.

  When rewriting an image, the electronic paper 1200 conveyed from the left in FIG. 3 is conveyed between the charging roller 800 and the counter electrode roller 501. Here, 1400 V as an alternating current component, a frequency of 500 Hz, and −1000 V as a direct current component are applied to the charging roller 800, whereby the surface of the electronic paper 1200 is charged to about −700 V. Note that the electronic paper 1200 is conveyed such that the conductive layer 1250 is on the upper side (the side opposite to the electrode head 104) in the drawing. Therefore, when the conductive layer 1250 comes into contact with the counter electrode roller 501, the upper side (the conductive layer 1250 side) of the electronic paper 1200 in the drawing can be grounded.

  On the other hand, 1400 V as an AC component, a frequency of 500 Hz, and −1000 V as a DC component are also applied to the film charging roller 210, whereby the surface of the cylindrical film 310 is charged to about −700 V. Thus, as in the first to third embodiments, the surface potential difference between the electronic paper 1200 and the cylindrical film 310 is made smaller than the discharge start voltage at the position immediately before the nip portion, thereby preventing abnormal discharge before image rewriting. It is out.

  The electronic paper 1200 in a charged state is transported to a nip portion between the cylindrical film 310 and a transport roller 401 disposed to face the electrode head 104. At this time, since the electronic paper 1200 and the cylindrical film 310 are charged to substantially the same potential, there is no possibility that electric discharge occurs between them. When the electronic paper 1200 is conveyed to the nip portion, 1000 V is applied to the electrode corresponding to the image display portion, thereby generating a discharge for rewriting the image and rewriting the image.

As described above, according to the present embodiment, even for the electronic paper 1200 having the conductive layer 1250, the image can be rewritten without causing abnormal discharge before the image is written. Further, as in the second and third embodiments, it is not necessary to separately perform an erasing process, so that high-speed rewriting of an image on the electronic paper 1000 can be performed.

  As described above, in an image rewriting apparatus for rewriting an image on a display medium holding charged particles, an image rewriting apparatus capable of obtaining good image quality without causing abnormal discharge between the display medium and the apparatus before rewriting the image. It becomes possible to provide.

[Fifth Embodiment]
An image rewriting apparatus according to a fifth embodiment to which the present invention is applicable will be described with reference to FIGS. 4 and 11. In addition, about the same structure as 1st-4th embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted and only a different point from 1st-4th embodiment is demonstrated here.

(5-1: Schematic configuration of image rewriting device)
FIG. 4 shows a schematic configuration of the image rewriting apparatus according to the present embodiment. The image rewriting apparatus according to this embodiment includes a thermal transfer electrode head 131, a head facing roller 400, a charging roller 800, a counter electrode roller 501, a film charging roller 210, and a film counter electrode roller 500. Yes. Moreover, the cylindrical film 320 with a conductive layer in which the dielectric layer is provided on the surface of one side is rotatably held as a film member. The cylindrical film 320 with a conductive layer has a cylindrical shape with an outer diameter of 30 mm and a thickness of 0.15 mm, and is seamlessly made of polyimide. Moreover, the inner surface of the cylindrical film 320 with a conductive layer is vapor-deposited with aluminum and connected to the ground.

  The writing head unit has a thermal transfer electrode head 131, a support 102, and a pressure spring 103. FIG. 11 shows a schematic configuration of the write head unit. The writing head unit has an alumina ceramic plate 135 on which a glass layer 136 having a convex cross section is formed. A heating resistor 137 is formed on the surface of the glass layer 136, and an Al electrode layer 138 is formed and patterned by a sputtering method thereon. Further, a protective layer 139 is formed on the Al electrode layer 138. The write head unit is provided with a driver IC 140 for selectively applying a voltage to each electrode, and an external wiring board for inputting an external drive signal is connected thereto.

(5-2: Image rewriting process)
An image rewriting process of the electronic paper 1000 will be described. The electronic paper 1000 conveyed from the left in FIG. 4 is charged to about −300 V by applying 1000 V as an AC component, a frequency of 500 Hz, and −600 V as a DC component to the charging roller 800. On the other hand, similarly, 1000 V as the AC component, 500 Hz as the AC component, and −600 V as the DC component are applied to the film charging roller 210, whereby the cylindrical film 320 with the conductive layer is charged to about −300V.

  In addition, the electronic paper 1000 charged with 300 V applied to the head facing roller 400 contacts the cylindrical film 320 with a conductive layer between the thermal transfer electrode head 131 and the head facing roller 400. At this time, since the absolute value of the surface potential difference between the electronic paper 1000 and the cylindrical film 320 with the conductive layer is smaller than the absolute value of the discharge start voltage at the position immediately before the nip portion, the occurrence of abnormal discharge before rewriting the image is prevented. Can do. In addition, it is necessary to make the dielectric layer in the cylindrical film 320 with a conductive layer come to the head facing roller side.

Thereafter, 28 V is applied to the electrode corresponding to the image display section in the nip. As a result, the heating resistor 137 formed on the thermal transfer electrode head 131 generates heat, and the discharge start voltage value (discharge threshold value) between the electronic paper 1000 and the cylindrical film 320 with a conductive layer decreases. Therefore, even when the voltage applied to the electrodes is low, a discharge necessary for image rewriting can be generated. When the discharge occurs, the image portion potential on the electronic paper 1000 becomes 100 V, the charged particles in the electronic paper 1000 move, and the image is switched.

  As described above, according to this embodiment, since the thermal transfer electrode head 131 is energized to generate heat, the discharge start voltage value at the time of image rewriting can be lowered, so that the switching voltage of the thermal transfer electrode head 131 can be lowered. it can. Therefore, the drive circuit of the thermal transfer electrode head 131 can be simplified and the price can be reduced. Further, as in the second to fourth embodiments, it is not necessary to perform an erasing process separately, so that high-speed rewriting of an image can be performed on the electronic paper 1000. In the above, the cylindrical film 320 with a conductive layer is used as the film member, but a dielectric film without a conductive layer may be used. That is, it is sufficient that a dielectric layer is provided at least on the electronic paper side, and the thermal transfer electrode head 131 side may be formed of a dielectric layer or a conductive layer.

  As described above, in an image rewriting apparatus for rewriting an image on a display medium holding charged particles, an image rewriting apparatus capable of obtaining good image quality without causing abnormal discharge between the display medium and the apparatus before rewriting the image. It becomes possible to provide.

DESCRIPTION OF SYMBOLS 100 ... Write head unit 104 ... Electrode head 200, 201 ... Static elimination head 300 ... Polyimide belt 400 ... Head opposing roller 1000 ... Electronic paper

Claims (4)

A dielectric film provided so as to be movable;
An electrode head in contact with the dielectric film;
An opposing roller disposed on the opposite side of the electrode head across the dielectric film;
With
In a state where a voltage is applied to the electrode head, a display medium that holds the charged particles in a movable manner is passed through the nip portion between the dielectric film and the opposing roller in the same direction as the movement direction of the dielectric film. In the image rewriting device capable of rewriting the image on the display medium at the nip portion,
A first potential change member that changes the surface potential of the display medium upstream of the nip portion in the conveyance direction of the display medium;
A second potential change member that changes a surface potential of the dielectric film upstream of the nip portion in the moving direction of the dielectric film;
Is provided,
The display medium after passing through the first potential change member is configured to be conveyed to the nip portion so as to gradually approach the dielectric film after passing through the second potential change member.
The surface potential of the display medium on the upstream side of the nip portion in the conveyance direction of the display medium and the movement direction of the dielectric film and on the downstream side of the first potential change member and the second potential change member The first potential change member and the first potential change member are arranged so that the absolute value of the potential difference of the surface potential of the dielectric film is smaller than the absolute value of the discharge start voltage between the display medium and the dielectric film immediately before the nip portion. An image rewriting device, wherein the two-potential changing member changes the surface potential of the display medium and the dielectric film, respectively. The first potential change member and the second potential change member are
The image rewriting device according to claim 1, wherein the image rewriting device is a charge removal member for removing charge from each of the display medium and the dielectric film. A film member provided movably and having a dielectric layer on at least one surface thereof;
An electrode head in contact with the film member and provided with a heating resistor;
A counter roller disposed on the opposite side of the electrode head across the film member;
With
Voltage can be applied to the electrode head, the heating resistor is energized to cause the heating resistor to generate heat, and the charged particles can move inside with the dielectric layer of the film member facing the opposing roller. In the image rewriting device capable of rewriting the image of the display medium in the nip portion by passing the display medium held in the nip portion between the film member and the opposing roller in the same direction as the moving direction of the film member.
A first potential change member that changes the surface potential of the display medium upstream of the nip portion in the conveyance direction of the display medium;
A second potential change member that changes the surface potential of the film member upstream of the nip portion in the moving direction of the film member;
Is provided,
The display medium after passing through the first potential change member is configured to be conveyed to the nip portion so as to gradually approach the film member after passing through the second potential change member.
The surface potential of the display medium on the upstream side of the nip portion in the conveyance direction of the display medium and the movement direction of the film member and on the downstream side of the first potential change member and the second potential change member The first potential change member and the second potential change so that the absolute value of the potential difference of the surface potential of the film member is smaller than the absolute value of the discharge start voltage between the display medium and the film member immediately before the nip portion. An image rewriting apparatus, wherein the member changes a surface potential of the display medium and the film member. The first potential change member and the second potential change member are
The image rewriting device according to claim 3, wherein the image rewriting device is a static elimination member that neutralizes a display medium and the film member.

Images