JP5810193B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that forms an image on a sheet and a fixing device that fixes an image on the sheet.

  As an apparatus for forming an image on a sheet, an image forming apparatus using a liquid developer is known. This type of image forming apparatus typically includes a fixing device for fixing an image on a sheet. The fixing device generates relatively high heat in order to melt the toner component in the liquid developer transferred onto the sheet (see, for example, Patent Document 1 and Patent Document 2).

JP 2008-90116 A JP 2009-98474 A

  The use of a liquid developer having the property that a polymer compound in which a pigment is dispersed precipitates on the sheet surface when the components (carrier solution) in the liquid developer penetrate into the sheet. Make it unnecessary. However, the present inventor has found that an image formed using a liquid developer having the above-described characteristics is easily peeled from the sheet.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus and a fixing apparatus that suppress peeling of an image from a sheet.

  An image forming apparatus according to an aspect of the present invention includes a conveyance element that conveys a sheet, an image forming unit that forms an image on the sheet using a liquid developer, and a fixing that fixes the image on the sheet. And the fixing device includes a rubbing element for rubbing the image on the sheet.

  According to the above configuration, the image forming unit forms an image on the sheet conveyed by the conveyance device using the liquid developer. The rubbing element of the fixing device for fixing the image on the sheet gives a frictional force to the image on the sheet. As a result, the component in the liquid developer that forms the image enters the surface layer of the sheet, and image peeling is suitably suppressed.

  In the above configuration, the conveying element conveys the sheet at a first speed, the fixing device includes a drive source for operating the rubbing element, and the rubbing element is applied to the image on the sheet. It is preferable that the drive source includes a contact surface that makes contact, and the drive source moves the contact surface at a second speed different from the first speed.

  According to the above configuration, the transport element transports the sheet at the first speed. In order to operate the rubbing element, the drive source moves the contact surface of the rubbing element in contact with the image on the sheet at a second speed different from the first speed. As a result, the component in the liquid developer that forms the image enters the surface layer of the sheet, and image peeling is suitably suppressed.

  In the above configuration, the conveying element conveys the sheet in the first direction, the fixing device includes a drive source for operating the rubbing element, and the rubbing element is applied to the image on the sheet. It is preferable that the drive source includes a contact surface that comes into contact, and the drive source moves the contact surface in a second direction different from the first direction.

  According to the above configuration, the conveyance element conveys the sheet in the first direction. In order to operate the rubbing element, the driving source moves the contact surface of the rubbing element in contact with the image on the sheet in a second direction different from the first direction. As a result, the component in the liquid developer that forms the image enters the surface layer of the sheet, and image peeling is suitably suppressed.

  In the above configuration, the fixing device includes a driving source for operating the rubbing element, the rubbing element includes a contact surface that contacts the image on the sheet, and the driving source includes the contact surface. Is preferably moved in a plurality of directions.

  According to the above configuration, the drive source moves the contact surface of the rubbing element in a plurality of directions. Therefore, the fixing power of the image to the sheet is preferably increased.

  The said structure WHEREIN: It is preferable that the said drive source reciprocates the said contact surface.

  According to the above configuration, the drive source reciprocates the contact surface of the rubbing element. Therefore, the fixing power of the image to the sheet is preferably increased.

  In the above configuration, the transport element transports the sheet in a first direction, and the drive source has a first cross direction that intersects the first direction and a first cross direction opposite to the first cross direction. It is preferable to include a first drive source that reciprocates in two intersecting directions.

  According to the above configuration, the drive source reciprocates the contact surface of the rubbing element in a direction crossing the sheet conveyance direction. Therefore, the fixing power of the image to the sheet is preferably increased.

  In the above configuration, the transport element transports the sheet at a first speed, and the drive source moves the contact surface in the first direction at a second speed different from the first speed. Preferably a source is included.

  According to the above configuration, the contact surface of the rubbing element rubs the image in the three directions of the first intersecting direction, the second intersecting direction, and the first direction. Therefore, the fixing power of the image to the sheet is preferably increased.

  In the above configuration, it is preferable that the drive source includes a second drive source that moves the contact surface in a direction opposite to the first direction.

  According to the above configuration, the contact surface of the rubbing element rubs the image in three directions, ie, the first intersecting direction, the second intersecting direction, and the direction opposite to the first direction. Therefore, the fixing power of the image to the sheet is preferably increased.

  In the above configuration, the rubbing element includes a contact cylinder that is rubbed against the sheet, a shaft that supports the contact cylinder, and a cam element that presses the shaft in the first intersecting direction. One drive source preferably rotates the cam element.

  According to the above configuration, the cam element rotated by the first drive source presses the shaft that supports the contact cylinder in the first intersecting direction. Therefore, the contact surface of the rubbing element is rubbed appropriately in the first intersecting direction.

  In the above configuration, it is preferable that the pressing mechanism includes a biasing element that biases the shaft in the second crossing direction.

  According to the above configuration, the biasing element biases the shaft supporting the contact cylinder in the second crossing direction. Therefore, as the cam element rotates, the shaft that supports the contact cylinder moves in the second intersecting direction. Therefore, the contact surface of the rubbing element is appropriately rubbed back and forth in the first intersecting direction and the second intersecting direction.

  In the above configuration, the shaft includes a first end contacting the cam element and a second end opposite to the first end, and the biasing element is disposed on the second end. It is preferable that the pressing mechanism includes a transmission element that is disposed adjacent to the second end, and the second driving source rotates the shaft via the transmission element.

  According to the above configuration, the shaft includes the first end contacting the cam element and the second end opposite to the first end. The biasing element is disposed adjacent to the second end and biases the shaft in the second crossing direction. The pressing mechanism includes a transmission element attached to the second end, and the second drive source rotates the shaft via the transmission element. Therefore, depending on the speed difference between the contact cylinder and the conveying element or the difference between the rotation direction of the contact cylinder and the conveying direction of the sheet conveyed by the conveying element, the contact surface of the rubbing element is changed between the first intersecting direction and the second intersecting direction. The image is rubbed in a direction along the sheet conveyance direction.

  The said structure WHEREIN: It is preferable that the said shaft supports the said contact cylinder rotatably.

  According to the said structure, a shaft supports a contact cylinder rotatably. Therefore, the contact cylinder rotates as the sheet is conveyed. Thus, the influence of the contact cylinder on the sheet conveyance is suppressed.

  In the above-described configuration, it is preferable that the transport element includes a press-contact portion that is pressed against the contact surface, and the sheet passes between the press-contact portion and the contact surface.

  According to the said structure, a sheet | seat passes between the press-contact part press-contacted toward a contact surface, and the said contact surface. As a result, a frictional force is appropriately applied to the image on the sheet.

  In the above configuration, the pressure contact portion includes a conveyance belt that conveys the sheet and a backup roller that presses the conveyance belt against the rubbing element, and the sheet passes between the conveyance belt and the contact surface. It is preferable to do.

  According to the above configuration, the sheet passes between the contact belt and the conveyance belt pressed against the contact surface by the backup roller. As a result, a frictional force is appropriately applied to the image on the sheet.

  The said structure WHEREIN: It is preferable to further provide the separation mechanism which separates the said backup roller with respect to the said rubbing element.

  According to the above configuration, the separation / contact mechanism separates the backup roller from the sliding contact element, thereby avoiding unnecessary wear of the transport belt and / or the sliding element.

  In the above configuration, it is preferable that the transport element includes an upstream holding roller disposed upstream of the rubbing element, and the backup roller includes an upstream backup roller that presses the transport belt against the upstream holding roller.

  According to the above configuration, the sheet is appropriately sandwiched between the upstream holding roller and the conveyance belt. Therefore, the influence on the sheet conveyance by the rubbing element is preferably reduced.

  In the above configuration, it is preferable that the transport element includes a downstream holding roller disposed downstream of the rubbing element, and the backup roller includes a downstream backup roller that presses the transport belt against the downstream holding roller.

  According to the above configuration, the sheet is appropriately sandwiched between the downstream holding roller and the conveyance belt. Therefore, the influence on the sheet conveyance by the rubbing element is preferably reduced.

  In the above configuration, the transport element includes an upstream holding roller disposed upstream of the rubbing element and a downstream holding roller disposed downstream of the rubbing element, and the rubbing element includes the upstream A rubbing roller pressed against the conveying belt between the holding roller and the downstream holding roller, the rubbing roller traveling the curved conveying belt between the upstream holding roller and the downstream holding roller It is preferable to define a route.

  According to the above configuration, the rubbing roller defines a traveling path of the conveyor belt that is curved between the upstream holding roller and the downstream holding roller. As a result, a relatively long rubbing time is ensured. Therefore, the fixing power of the image to the sheet is preferably increased.

  The said structure WHEREIN: It is preferable that the said contact surface contains a nonwoven fabric.

  According to the said structure, since a contact surface contains a nonwoven fabric, the frictional force between a sheet | seat and a conveyance element hardly inhibits conveyance of a sheet | seat.

  In the above configuration, the liquid developer includes colored particles for coloring the image, a carrier liquid in which the colored particles are dispersed, and a polymer compound dissolved or swollen in the carrier liquid. Is preferred.

  According to the above configuration, the polymer compound in the carrier solution in which the colored particles for coloring the image are dispersed forms a film on the image surface. As a result, the scratch resistance of the image is improved. Thus, image damage due to friction between the rubbing element and the image is appropriately suppressed.

  A fixing device according to another aspect of the present invention includes a rubbing element that rubs an image formed using a liquid developer.

  According to the above configuration, the rubbing element of the fixing device gives a frictional force to the image formed using the liquid developer. As a result, the component in the liquid developer that forms the image enters the surface layer of the sheet, and image peeling is suitably suppressed.

  As described above, the image forming apparatus and the fixing device according to the present invention can suppress peeling of the image from the sheet.

It is a schematic diagram which shows roughly the transfer process using a liquid developer. FIG. 2 is a schematic diagram schematically showing the principle of a fixing step after the transfer step shown in FIG. 1. 3 is a graph schematically showing a relationship between rubbing time and fixing rate. It is a graph which shows roughly the result of the screening test to various nonwoven fabric materials. FIG. 3 is a plan view schematically showing a fixing device to which the fixing principle shown in FIG. 2 is applied. FIG. 6 is a schematic side view of the fixing device shown in FIG. 5. FIG. 6 is a schematic side view of the fixing device shown in FIG. 5. FIG. 6 is a cross-sectional view schematically showing an image forming apparatus to which the principle of the fixing device shown in FIG. 5 is applied. 1 is a schematic cross-sectional view of an image forming apparatus excluding a portion of a circulation device. It is sectional drawing which expands and shows one of the image forming units of the image forming apparatus shown by FIG. FIG. 10 is a schematic diagram illustrating a test for verifying a fixing principle according to a second embodiment. It is a graph which shows the result of the test shown by FIG. FIG. 6 is a schematic plan view of a fixing device according to a second embodiment. FIG. 14 is a plan view schematically showing an operation of the fixing device shown in FIG. 13. FIG. 14 is a schematic side view of the operation of the fixing device shown in FIG. 13. FIG. 14 is a schematic side view of the operation of the fixing device shown in FIG. 13. FIG. 10 is a schematic side view of a fixing device according to a third embodiment. FIG. 10 is a schematic side view of a fixing device according to a third embodiment. It is a figure which shows schematically the rubbing roller of the fixing device which concerns on 4th Embodiment.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. Note that terms used in the following description, such as “up”, “down”, “left”, “right” and the like, are merely for the purpose of clarifying the explanation and do not limit the present invention. Not what you want.

<Fixing principle>
FIG. 1 is a diagram schematically illustrating an image transfer process using a liquid developer. The transfer process proceeds in the order of FIG. 1 (a) to FIG. 1 (c). With reference to FIG. 1, the transfer of the image to the sheet and the image after the transfer will be described.

  FIG. 1A shows a schematic cross section of a liquid layer L of a liquid developer that forms an image transferred from the image carrier 100 to the sheet S. FIG. The image carrier 100 may be, for example, a transfer belt provided in an image forming apparatus (for example, a printer, a copier, a facsimile machine, or a multifunction machine having these functions) that forms an image using a liquid developer. The image carrier 100 conveys the liquid layer L of the liquid developer that forms an image to the transfer position to the sheet S.

  At the transfer position, the sheet S contacts the liquid layer L on the image carrier 100. The liquid layer L of the liquid developer that forms an image includes a carrier liquid C, colored particles P for coloring the image, and a polymer compound R dissolved or swollen in the carrier liquid C. The colored particles P dispersed in the carrier liquid C are electrostatically attracted to the sheet S. Thus, the colored particles P adhere on the sheet S and form an image. Note that the attracting of the colored particles P to the sheet S is achieved by, for example, an electric field across the sheet S. The principle regarding the attracting of the colored particles P to the sheet S will be described in detail in relation to an image forming apparatus described later.

  FIG. 1 (b) schematically shows the carrier liquid C that penetrates the sheet S. The carrier liquid C having a relatively low kinematic viscosity permeates the sheet S, and forms a permeation layer PL on the surface layer of the sheet S. As the carrier liquid C penetrates the sheet S, the concentration of the polymer compound R in the liquid layer L of the liquid developer increases.

  As shown in FIG. 1C, when the carrier liquid C further penetrates the sheet S, the polymer compound R in the liquid layer L is deposited. As described above, the electrostatic adhesion of the colored particles P to the sheet S occurs prior to the precipitation of the polymer compound R. Therefore, the polymer compound R deposited on the surface of the sheet S forms a coating layer laminated on the layer of the colored particles P that form an image on the sheet S.

  FIG. 2 is a diagram schematically illustrating a fixing process performed after the transfer process. FIG. 2A schematically shows the fixing process. FIG. 2B is a schematic cross-sectional view of the sheet S after the fixing process. The principle of the fixing process will be described with reference to FIGS.

  After the transfer step, the carrier liquid C is substantially permeated into the sheet S, and the image layer I including the polymer compound R and the colored particles P is formed on the sheet S. In the transfer process, almost no physical force is applied to the image layer I except for the pressure and electric field when the liquid layer L (image) is transferred from the image carrier 100 to the sheet S. For this reason, before the fixing step, the physical bond between the image layer I and the sheet S is relatively weak, and when the peeling test using a tape described later is performed, the image layer I is noticeably peeled off. It will be.

  FIG. 2A shows a rubbing plate 200 exemplified as a fixing device and / or a rubbing element. The rubbing plate 200 includes, for example, a substantially rectangular parallelepiped substrate 210 and a nonwoven fabric 220 that covers the surface of the substrate 210. In this embodiment, the layer of the nonwoven fabric 220 which forms the lower surface of the rubbing plate 200 facing the image layer I is exemplified as the contact surface. In this embodiment, a polypropylene nonwoven fabric is used as the nonwoven fabric 220. Alternatively, a non-woven fabric (hereinafter referred to as PTFE felt A) made of polytetrafluoroethylene (PTFE) having a dynamic friction coefficient of 0.10, polytetrafluoroethylene (PTFE) having a dynamic friction coefficient of 0.13. : Polytetrafluoroethylen) non-woven fabric (hereinafter referred to as PTFE felt B), polyester felt, polyethylene terephthalate felt (hereinafter referred to as PET felt), polyamide felt or wool felt may be used as the non-woven fabric 220. Good.

  The rubbing plate 200 placed on the image layer I formed on the sheet S moves on the image layer I along the upper surface of the sheet S. As a result, as shown in FIG. 2B, part of the components of the image layer I (colored particles P and / or polymer compound R) bite into the surface layer of the sheet S (anchor effect). Thus, the physical coupling between the image layer I and the sheet S is strengthened.

  As described above, the upper surface of the image layer I is covered with the polymer compound R. Therefore, the colored particles P that develop an image are appropriately protected from the rubbing operation of the rubbing plate 200 by the polymer compound R. Thus, image damage due to rubbing of the rubbing plate 200 is appropriately suppressed.

<Test example>
FIG. 3 is a graph schematically showing the relationship between the period (rubbing time) when the rubbing plate 200 is slidingly moved to the image layer I and the fixing rate of the image layer I. The relationship between the rubbing time and the fixing rate will be described with reference to FIGS.

  The rubbing time indicated on the horizontal axis of the graph of FIG. 3 represents the length of time during which a predetermined area in the image layer I is in contact with the rubbing plate 200 that is reciprocating.

The fixing rate FR shown on the vertical axis of the graph of FIG. 3 is calculated using the following mathematical formula. Here, D ₀ represents the density of the image before peeling the tape attached on the image layer I, and D ₁ is the density of the image after peeling the tape attached on the image layer I. Represents.

  The tape used for evaluation of the fixing rate FR was a mending tape manufactured by 3M. The mending tape was attached onto the image layer I using a dedicated jig. Accordingly, the adhesion strength between the image layer I and the mending tape in the test sample is kept substantially constant between the data points shown in the graph of FIG. Further, the mending tape punched on the image layer I in the test sample was peeled from the image layer I at a substantially constant peeling angle and a substantially constant peeling speed using a dedicated jig.

  The density of the image of the test sample was measured using a spectrophotometer spectroeye manufactured by Sakata Inx Engineering Co., Ltd.

  As shown in FIG. 3, when the image layer I is rubbed for 1 second or more, it can be seen that the image layer I achieves a relatively high fixing rate FR. Further, it can be seen that the fixing rate FR of the image layer I shows a rapid increase when the rubbing time is less than 1 second. It should be noted that the weight of the rubbing plate 200 is preferably determined appropriately so that generation of scratches on the surface of the image layer I is suppressed.

  FIG. 4 is a graph schematically showing the relationship between various types of nonwoven fabric 220 and the fixing rate FR. The relationship between the type of the nonwoven fabric 220 and the fixing rate FR will be described with reference to FIGS.

  The horizontal axis in FIG. 4 indicates the type of nonwoven fabric 220. In this test, PTFE felt A, PTFE felt B, polypropylene nonwoven fabric, polyester felt, PET felt, polyamide felt and wool felt are shown.

  The vertical axis on the left side of FIG. 4 indicates the above-described fixing rate FR. The fixing rate FR is represented by the bar graph of FIG. In addition, the above-mentioned all types of nonwoven fabrics 220 used in this test achieved a relatively high fixing rate FR in a rubbing time exceeding 1 second. Therefore, for the screening of a relatively advantageous type of nonwoven fabric 220, the fixing rate FR shown in FIG. 4 is calculated under a rubbing time of 0.625 seconds.

  The vertical axis on the right side of FIG. 4 indicates the dynamic friction coefficient of each type of nonwoven fabric 220 represented by the points in FIG. A low coefficient of dynamic friction is advantageous in terms of reducing the influence on the conveyance of the sheet S and reducing damage to the image layer I.

  As shown in FIG. 4, PTFE felt A has the lowest coefficient of dynamic friction and achieves the highest fixing rate FR. Thus, it can be seen that PTFE felt A is the most advantageous of the types of nonwovens 220 tested. In addition, the nonwoven fabric material which is not shown by FIG. Preferably, a nonwoven fabric material having a dynamic friction coefficient of 0.50 or less is used as the nonwoven fabric 220. The nonwoven fabric material having a dynamic friction coefficient of 0.50 or less can suitably suppress the influence on the conveyance of the sheet S and the damage to the image layer I.

<Fixing device>
FIG. 5 is a schematic plan view of a fixing device that fixes the image layer I to the sheet S using the above-described fixing principle and a conveying device that conveys the sheet S passing through the fixing device. The fixing device will be described with reference to FIGS.

  The fixing device 300 includes a rubbing roller 310 disposed so as to be in contact with the upper surface of the sheet S. The rubbing roller 310 includes a cylindrical contact cylinder 311 that contacts the upper surface of the sheet S, and a shaft 312 that protrudes from both end faces of the contact cylinder 311. One end of the shaft 312 is rotatably supported by a bearing housed in the housing 320. A gear 321 is attached to the other end of the shaft 312. An image is formed on the upper surface of the sheet S shown in FIG. 5 using a liquid developer. The contact cylinder 311 that rubs the image on the upper surface of the sheet S is exemplified as a rubbing element.

  The fixing device 300 includes a motor 330 coupled to the gear 321. In the present embodiment, the motor 330 that gives the contact cylinder 311 a rotation operation is exemplified as a drive source.

  The conveying device includes an upstream conveying device 410 disposed upstream of the fixing device 300 and a downstream conveying device 420 disposed downstream of the fixing device 300. The upstream transport device 410 and the downstream transport device 420 are exemplified as transport elements that transport the sheet S. FIG. 5 shows a vector from the upstream conveyance device 410 toward the downstream conveyance device 420. The direction of the vector in FIG. 5 is exemplified as a first direction D <b> 1 that means the conveyance direction of the sheet S. Further, the magnitude of the vector in FIG. 5 is exemplified as the first speed V <b> 1 that means the conveyance speed of the sheet S. The upstream conveying device 410 and the downstream conveying device 420 cooperate to convey the sheet S in the first direction D1 at the first speed V1.

  FIG. 6 is a schematic side view of the fixing device 300 and the conveying device (upstream conveying device 410 and downstream conveying device 420). The fixing device 300 and the conveying device (the upstream conveying device 410 and the downstream conveying device 420) will be described with reference to FIGS.

  The upstream conveying device 410 includes an upper roller 411 that contacts the upper surface of the sheet S and a lower roller 412 that contacts the sheet S. The upper roller 411 includes a pair of journals 413 and 414. The journal 413 is rotatably supported by a bearing accommodated in the housing 415. A gear 416 is attached to the journal 414.

  The upstream conveyance device 410 includes an upstream motor 417. The upstream motor 417 is connected to the gear 416.

  The upstream conveyance device 410 includes an upstream support mechanism 430 that elastically supports the lower roller 412. The lower roller 412 includes a journal 418 connected to the upstream support mechanism 430.

  The upstream support mechanism 430 includes a bearing portion 431 that rotatably supports the journal 418, and an elastic element 432 that is connected to the support surface F and the bearing portion 431 that support the upstream transport device 410, the downstream transport device 420, and the fixing device 300. For example, a coil spring). The lower roller 412 pushed upward by the elastic element 432 sandwiches the sheet S in cooperation with the upper roller 411. As a result, the sheet S sandwiched between the upper roller 411 and the lower roller 412 is conveyed toward the fixing device 300 by driving the upstream motor 417.

  The downstream conveying device 420 includes an upper roller 421 that contacts the upper surface of the sheet S and a lower roller 422 that contacts the sheet S. The upper roller 421 includes a pair of journals 423 and 424. The journal 423 is rotatably supported by a bearing accommodated in the housing 425. A gear 426 is attached to the journal 424.

  The downstream transport device 420 includes a downstream motor 427. The downstream motor 427 is connected to the gear 426.

  The downstream transport device 420 includes a downstream support mechanism 440 that elastically supports the lower roller 422. The lower roller 422 includes a journal 428 connected to the downstream support mechanism 440.

  The downstream support mechanism 440 includes a bearing portion 441 that rotatably supports the journal 418, and an elastic element 442 that is connected to the support surface F and the bearing portion 441 that support the upstream transport device 410, the downstream transport device 420, and the fixing device 300. For example, a coil spring). The lower roller 422 pushed upward by the elastic element 442 holds the sheet S in cooperation with the upper roller 421. As a result, the sheet S sandwiched between the upper roller 421 and the lower roller 422 is pulled out of the fixing device 300 by driving the downstream motor 427.

  As shown in FIG. 6, the contact cylinder 311 includes a substantially cylindrical elastic layer 313 that surrounds the peripheral surface of the shaft 312, and a nonwoven fabric layer 314 that covers the outer peripheral surface of the elastic layer 313. The elastic layer 313 is formed using, for example, a sponge or another elastic material having a relatively high flexibility. Nonwoven fabric layer 314 is formed using, for example, a nonwoven fabric of the type described in connection with FIG.

  The fixing device 300 includes a backup roller 340 disposed below the rubbing roller 310. The backup roller 340 includes a substantially cylindrical support cylinder 341 formed using a sponge or other elastic material having relatively high flexibility, and a metal shaft 342 inserted through the support cylinder 341.

  The fixing device 300 includes a pressing mechanism 350 that presses the backup roller 340 against the rubbing roller 310. The pressure contact mechanism 350 includes a bearing portion 351 that rotatably supports both end portions of the shaft 342 protruding from the end surface of the support cylinder 341, a support surface F that supports the upstream conveyance device 410, the downstream conveyance device 420, and the fixing device 300, and a bearing. And an elastic element 352 (for example, a coil spring) connected to the portion 351.

  The elastic element 352 biases the backup roller 340 toward the rubbing roller 310. As a result, the nonwoven fabric layer 314 and / or the elastic layer 313 are compressed and deformed to form a substantially flat upper nip surface N1 along the upper surface of the sheet S passing through the fixing device 300. Similarly, the peripheral surface of the support cylinder 341 is compressed and deformed to form a substantially flat lower nip surface N2 along the lower surface of the sheet S passing through the fixing device 300. In the present embodiment, the upper nip surface N1 that contacts the image (image layer I) formed on the upper surface of the sheet S is exemplified as the contact surface. In addition, the support cylinder 341 that is press-contacted toward the upper nip surface N1 is exemplified as a press-contact portion.

  A vector shown above the upper nip surface N1 shown in FIG. 6 indicates the moving direction and size of the upper nip surface N1. The motor 330 rotates the rubbing roller 310 so that the upper nip surface N1 moves in the first direction D1. The number of rotations of the motor 330 is set so that the upper nip surface N1 moves at a second speed V2 different from the first speed V1 defined by the upstream transport apparatus 410 and the downstream transport apparatus 420. As a result, the image layer I formed on the sheet S is rubbed against the upper nip surface N1 while passing between the upper nip surface N1 and the lower nip surface N2, and will be described with reference to FIG. It is fixed according to the principle. The second speed V2 shown in FIG. 6 is greater than the first speed V1. Alternatively, the second speed V2 may be smaller than the first speed V1.

  In the present embodiment, the difference between the first speed V1 and the second speed V2 is the relationship between the rotational speed of the motor 330 and the rotational speed of the upstream motor 417 / downstream motor 427 and / or the diameter of the rubbing roller 310. And the diameter of the upper rollers 411 and 421. In the present embodiment, motors 330, 417, and 427 are individually assigned to the fixing device 300, the upstream conveyance device 410, and the downstream conveyance device 420, respectively. Alternatively, each of the fixing device 300, the upstream conveyance device 410, and the downstream conveyance device 420 may be driven using a common motor as a drive source. A difference between the first speed V1 and the second speed V2 may be created by a gear mechanism formed between the common motor and each of the fixing device 300, the upstream transport device 410, and the downstream transport device 420. .

  In the present embodiment, a single fixing device 300 is disposed between the upstream conveyance device 410 and the downstream conveyance device 420. Alternatively, a plurality of fixing devices 300 may be disposed between the upstream conveyance device 410 and the downstream conveyance device 420. The plurality of fixing devices 300 contribute to extending the rubbing time described with reference to FIG.

  FIG. 7 schematically shows another operation of the fixing device 300. Another operation of the fixing device 300 will be described with reference to FIGS.

  The motor 330 may rotate the rubbing roller 310 so that the upper nip surface N1 moves in the second direction D2 opposite to the first direction D1. As described above, the nonwoven fabric layer 314 having a relatively low dynamic friction coefficient allows stable conveyance of the sheet S under the rotation of the rubbing roller 310 in the direction opposite to the conveyance direction of the sheet S.

<Application to image forming apparatus>
FIG. 8 is a schematic configuration diagram of an image forming apparatus to which the principle of the fixing technique described with reference to FIGS. 1 to 7 is applied. FIG. 9 is a schematic sectional view of the color printer excluding the portion of the circulation device. FIG. 10 is an enlarged cross-sectional view of one of the image forming units. The image forming apparatus will be described with reference to FIGS. 1 and 5 to 10. The image forming apparatus shown in FIGS. 8 to 10 is a color printer. Alternatively, the image forming apparatus may be a copier, a facsimile machine, a multifunction machine including these functions, or another apparatus capable of forming an image on the sheet S.

  As shown in FIG. 8, the color printer 1 includes an upper main body 1A that stores various units and parts for image formation, and a lower part of the upper main body 1A. And a lower main body 1B in which LM, LC, and LB (mixed liquid supply system) are stored. Here, the piping connecting the upper main body 1A and the lower main body 1B is not shown. The circulation devices LY, LM, LC, and LB circulate the liquid developer used in the image forming process executed in the upper main body 1A. For the configurations and principles of the circulation devices LY, LM, LC, and LB, a circulation technique for a liquid developer used in a known image forming apparatus may be used as appropriate.

  As shown in FIG. 9, the upper main body 1 </ b> A is formed of a tandem image forming unit 2 that forms a toner image based on image data, a sheet storage unit 3 that stores a sheet S, and an image forming unit 2. A secondary transfer unit 4 for transferring the transferred toner image onto the sheet S, a fixing unit 5 for fixing the transferred toner image on the sheet S, a discharge unit 6 for discharging the sheet S after the fixing, and a sheet A sheet conveying unit 7 that conveys the sheet S from the storage unit 3 to the discharge unit 6. In this embodiment, the principle of the fixing technique described with reference to FIGS. 1 to 7 is applied to the fixing unit 5.

  The image forming unit 2 includes an intermediate transfer belt 21, a cleaning unit 22 for the intermediate transfer belt 21, and an image forming unit corresponding to each of yellow (Y), magenta (M), cyan (C), and black (Bk). FY, FM, FC, and FB. In the present embodiment, the intermediate transfer belt 21 corresponds to the image carrier 100 described with reference to FIG.

  The image forming unit 2 includes a drive roller 41 for driving the loop-shaped intermediate transfer belt 21 and a driven roller 49 that rotates as the intermediate transfer belt 21 travels. The conductive intermediate transfer belt 21 is wound around a driving roller 41 and a driven roller 49. The width of the intermediate transfer belt 21 is set larger than the maximum width sheet S allowed by the color printer 1. In the present embodiment, the driving roller 41 corresponds to the upper roller 411 of the upstream conveying device 410 described with reference to FIGS. The upward conveying direction of the sheet S defined by the drive roller 41 is exemplified as the first direction D1. Further, the conveyance speed of the sheet S defined by the driving roller 41 is exemplified as the first speed V1. In the following description, the surface facing outward in the circulation drive of the intermediate transfer belt 21 is referred to as the front surface, and the other surface is referred to as the back surface.

  The image forming units FY, FM, FC, and FB connected in the vicinity of the intermediate transfer belt 21 are disposed between the cleaning unit 22 and the secondary transfer unit 4 of the intermediate transfer belt 21. The image forming units FY, FM, FC, and FB include a photosensitive drum 10, a charger 11, an exposure device 12, a developing device 14, a primary transfer roller 20, a cleaning device 26, a charge removal device 13, and a removal device. And a roller 30. Note that, among the image forming units FY, FM, FC, and FB, the image forming unit FB located closest to the secondary transfer unit 4 does not include the removal roller 30, and the image forming units FY, The configuration is similar to that of FM and FC.

  Corresponding to each image forming unit FY, FM, FC, FB, circulation devices LY, LM, LC, LB are provided, respectively. The circulation devices LY, LM, LC, and LB supply and collect the liquid developer of each color.

  The circumferential surface of the cylindrical photosensitive drum 10 can carry a toner image including a charged toner (charged to a positive polarity in this embodiment). The photosensitive drum 10 that contacts the intermediate transfer belt 21 rotates along the running direction of the intermediate transfer belt 21. The charger 11 uniformly charges the surface of the photosensitive drum 10.

  The exposure device 12 has, for example, an LED light source. The light source of the exposure device 12 irradiates light onto the uniformly charged surface of the photosensitive drum 10 in accordance with image data input from an external device. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 10.

  The developing device 14 that holds the liquid developer containing the colored particles P, the carrier liquid C, and the polymer compound R so as to face the electrostatic latent image on the surface of the photoconductor drum 10 includes the colored particles P And polymer compound R is deposited. As a result, the electrostatic latent image is developed as an image colored by the colored particles P.

  As shown in FIG. 10, the developing device 14 includes a developing container 140, a developing roller 141, a supply roller 142, a support roller 143, a blade 144 pressed against the supply roller 142, a blade 145 for cleaning the developing roller 141, A collecting device 146 for collecting the liquid developer and a charger 147 for charging the developing roller 141 are included.

  The liquid developer in which the concentration of the colored particles P and the polymer compound R in the carrier liquid C has been adjusted in advance is supplied from the supply nozzle 278 to the developing container 140. The liquid developer is supplied toward the nip portion between the supply roller 142 and the support roller 143. Excess liquid developer falls below the support roller 143 and is stored at the bottom of the developing container 140. The stored liquid developer is collected through the pipe 82 using the circulation devices LY, LM, LC, and LB.

  The support roller 143 disposed substantially at the center of the developing container 140 contacts the upper supply roller 142 to form a nip portion. A groove for holding the liquid developer is formed on the peripheral surface of the supply roller 142.

  The liquid developer supplied from the supply nozzle 278 is temporarily retained at the nip portion between the support roller 143 and the supply roller 142. In the nip portion, the liquid developer held in the groove of the supply roller 142 is carried to the upper developing roller 141. The blade 144 brought into pressure contact with the peripheral surface of the supply roller 142 adjusts the amount of liquid developer held by the supply roller 142. Excess liquid developer scraped off by the blade 144 is received at the bottom of the developing container 140.

  The developing roller 141 disposed in the upper opening of the developing container 140 is in contact with the supply roller 142. The rotation direction of the developing roller 141 and the supply roller 142 is determined so that the peripheral surface of the developing roller 141 moves in the opposite direction to the supply roller 142 at the nip portion between the developing roller 141 and the supply roller 142. As a result, the liquid developer held on the peripheral surface of the supply roller 142 is delivered to the peripheral surface of the developing roller 141. Since the layer thickness of the liquid developer on the supply roller 142 is appropriately adjusted, the liquid developer layer formed on the surface of the developing roller 141 has a thickness appropriate for image formation.

  The surface of the developing roller 141 that has received the liquid developer moves above the charger 147. The charger 147 provides a charging potential having the same polarity as the charging polarity of the colored particles P. As a result, the colored particles P in the liquid developer carried on the developing roller 141 move to the surface side of the developing roller 141.

  The surface of the developing roller 141 that has passed through the charger 147 is in contact with the photosensitive drum 10. A toner image corresponding to the image data is formed on the surface of the photosensitive drum 10 by the potential difference between the electrostatic latent image potential on the surface of the photosensitive drum 10 and the developing bias applied to the developing roller 141.

  After contacting the photoconductor drum 10, the peripheral surface of the developing roller 141 contacts the blade 145. The blade 145 removes the liquid developer on the surface of the developing roller 141 that has completed the developing operation on the photosensitive drum 10.

  The collection device 146 collects the liquid developer removed by the blade 145 and sends the liquid developer to the pipe 81 of the circulation devices LY, LM, LC, and LB. The liquid developer flows down along the surface of the blade 145. If the viscosity of the liquid developer is high, the recovery device 146 may preferably include a feed roller that assists in feeding the liquid developer.

  The primary transfer roller 20 sandwiches the intermediate transfer belt 21 in cooperation with the photosensitive drum 10. A voltage having a polarity opposite to that of the colored particles P on the photosensitive drum 10 (minus in the present embodiment) is applied to the primary transfer roller 20 from a power source (not shown). The primary transfer roller 20 applies a voltage having a polarity opposite to that of the toner to the intermediate transfer belt 21. As a result, the colored particles P and the polymer compound R are attracted to the surface of the conductive intermediate transfer belt 21. Thus, the image formed on the photosensitive drum 10 is transferred to the surface of the intermediate transfer belt 21. Thereafter, the intermediate transfer belt 21 carries the toner image and conveys it to the sheet S.

  The cleaning device 26 that removes the liquid developer remaining without being transferred from the photosensitive drum 10 to the intermediate transfer belt 21 includes a conveying screw 261 and a cleaning blade 262. An end portion of the plate-like cleaning blade 262 extending in the rotation axis direction of the photosensitive drum 10 is in sliding contact with the surface of the photosensitive drum 10. The cleaning blade 262 scrapes off the liquid developer remaining on the photosensitive drum 10 as the photosensitive drum 10 rotates. The liquid developer thus scraped off is temporarily stored in the cleaning device 26. A conveying screw 261 in the cleaning device 26 conveys the residual developer to the outside.

  In order to prepare for the next round of image formation, the static elimination device 13 having a static elimination light source removes the liquid developer by the cleaning blade 262 and then neutralizes the surface of the photosensitive drum 10 with light from the light source.

  The substantially cylindrical removal roller 30 contacts the intermediate transfer belt 21. A removing roller 30 disposed between the image forming unit FY and the image forming unit FM removes the carrier liquid C from the liquid developer transferred from the image forming unit FY to the intermediate transfer belt 21. A removing roller 30 disposed between the image forming unit FM and the image forming unit FC removes the carrier liquid C from the liquid developer transferred from the image forming unit FM to the intermediate transfer belt 21. A removing roller 30 disposed between the image forming unit FC and the image forming unit FB removes the carrier liquid C from the liquid developer transferred from the image forming unit FC to the intermediate transfer belt 21. As described above, since the image forming unit FB does not include the removal roller 30, the intermediate transfer belt 21 carries a liquid developer containing the carrier liquid C, like the image carrier 100 shown in FIG.

  As shown in FIG. 9, the sheet storage unit 3 that stores the sheet S is disposed below the upper main body 1 </ b> A. The sheet storage unit 3 includes a paper feed cassette that can store the sheets S.

  The secondary transfer unit 4 that transfers the image formed on the intermediate transfer belt 21 to the sheet S includes a secondary transfer roller 42 disposed to face the drive roller 41 that drives the intermediate transfer belt 21. The secondary transfer roller 42 corresponds to the lower roller 412 of the upstream conveying device 410 described with reference to FIGS. The secondary transfer roller 42 generates an electric field with the intermediate transfer belt 21 and draws the colored particles P toward the sheet S as described with reference to FIG.

  The fixing unit 5 disposed on the upper side of the secondary transfer unit 4 fixes the toner image on the sheet S by using the principle of the fixing technique described with reference to FIGS. 1 to 7. Accordingly, the fixing unit 5 includes the rubbing roller 310 and the backup roller 340 described with reference to FIGS. As described above, the fixing process is suitably performed by the rubbing of the rubbing roller 310 against the image on the sheet S. In addition, since the rubbing roller 310 has a sufficient width to rub the entire image, the gloss of the image is uniformly changed by the contact with the rubbing roller 310. As a result, even if the image on the sheet S is subsequently touched by the user, the local change in the gloss of the image is preferably suppressed.

  The sheet S on which the toner image is fixed by the fixing unit 5 is discharged to the discharge unit 6 disposed at the upper part of the color printer 1. A sheet conveyance unit 7 including a plurality of conveyance roller groups conveys the sheet S in the order of the secondary transfer unit 4, the fixing unit 5, and the discharge unit 6 from the sheet storage unit 3.

<Liquid developer>
As described above, the liquid developer includes an electrically insulating carrier liquid C and colored particles P dispersed in the carrier liquid C. The liquid developer contains the polymer compound R. Preferably, the liquid developer has a viscosity of 30 to 400 mPa · s at a measurement temperature of 25 ° C. More preferably, the viscosity (measurement temperature 25 ° C.) of the liquid developer is 40 to 300 mPa · s, and more preferably 50 to 250 mPa · s.

<Carrier liquid>
The electrically insulating carrier liquid C that functions as a liquid carrier enhances the electrical insulation of the liquid developer. As the electrically insulating carrier liquid C, for example, an electrically insulating organic solvent having a volume resistance at 25 ° C. of 10 ¹² Ω · cm or more (in other words, conductivity of 1.0 pS / cm or less) is preferable. Furthermore, in addition to the above physical properties, those capable of dissolving a polymer compound R described later (a polymer compound R having a relatively high solubility) are preferably used.

  Further, the viscosity, type, and blending amount of the carrier liquid C are appropriately adjusted and selected so that the viscosity of the entire liquid developer (measurement temperature: 25 ° C.) is 30 to 400 mPa · s. The viscosity of the liquid developer also depends on the combination of the organic solvent used as the carrier liquid C and the polymer compound R described later. Therefore, the type and blending amount of the organic solvent are appropriately determined according to the desired viscosity of the liquid developer and the type of the polymer compound R selected.

  Examples of such an electrically insulating organic solvent include aliphatic hydrocarbons and vegetable oils that are liquid at room temperature.

  As the aliphatic hydrocarbon, for example, liquid n-paraffinic hydrocarbon, iso-paraffinic hydrocarbon, halogenated aliphatic hydrocarbon, branched aliphatic hydrocarbon or a mixture thereof is preferable. For example, n-hexane, n-heptane, n-octane, nonane, decane, dodecane, hexadecane, heptadecane, cyclohexane, perchloroethylene, and trichloroethane are used as the aliphatic hydrocarbon. From the viewpoint of environmental measures (measures against VOC), non-volatile organic solvents and organic solvents with relatively low volatility (for example, those having a boiling point of 200 ° C. or higher) are preferable, for example, aliphatic carbonization having 16 or more carbon atoms. Liquid paraffin containing a relatively large amount of hydrogen is preferably used.

  Examples of vegetable oils include tall oil fatty acids (main components: oleic acid, linoleic acid), fatty acid esters derived from vegetable oils, soybean oil, safflower oil, castor oil, linseed oil, and tung oil. Of these, tall oil fatty acids are preferably used.

  As the carrier liquid C, for example, liquid paraffin “Moresco White P-55”, “Moresco White P-40”, “Moresco White P-70”, “Moresco White P-200” manufactured by Matsumura Oil Research Co., Ltd. ”; Tall oil fatty acids“ Hartol FA-1 ”,“ Hartol FA-1P ”,“ Hartol FA-3 ”manufactured by Harima Chemicals Co., Ltd .; vegetable oil-based solvent“ Vegisol MT ”,“ Vegisol CM ”manufactured by Kaneda Co., Ltd. “Vegisol MB”, “Vegisol PR”, vegetable oil “Tung oil”; “Isopar G”, “Isopar H”, “Isopar K”, “Isopar L”, “Isopar M”, “Isopar V” manufactured by ExxonMobil; Liquid paraffin “Cosmo White P-60”, “Cosmo White P-70”, “Cosmo White P-12” manufactured by Cosmo Oil Co., Ltd. ”; Vegetable oil“ soybean oil white squeezed oil S ”,“ linseed oil ”,“ saflower oil ”manufactured by Nisshin Oilio Co., Ltd .; vegetable oils“ castor oil LAV ”,“ castor oil industry ”manufactured by Ito Oil Co., Ltd. are used. Also good.

  In this embodiment, as long as the polymer compound R is dissolved in the carrier liquid C, only the carrier liquid C having a relatively high solubility of the polymer compound R (good solvent for the polymer compound R) may be used. Alternatively, a polymer compound R having a relatively low solubility (poor solvent for polymer compound R) may be used in combination. Depending on the type of carrier liquid C, the conductivity of the entire carrier liquid C (conductivity of the liquid developer) is appropriately adjusted so as not to be excessively high. For example, vegetable oils such as tall oil fatty acids generally have higher electrical conductivity than aliphatic hydrocarbons such as liquid paraffin. Therefore, in order to dissolve the polymer compound R in the carrier liquid C satisfactorily, when the oils described above are included as the carrier liquid C, it is preferable to adjust the conductivity relatively carefully.

  The carrier liquid C having a high oil content is advantageous in terms of the solubility of the polymer compound R, but disadvantageous in terms of conductivity. The carrier liquid C having a low oil content is advantageous in terms of conductivity, but is disadvantageous in terms of the solubility of the polymer compound R.

  The content of the aforementioned oils in the carrier liquid C depends on the type and content of the polymer compound R contained in the liquid developer. As content of suitable oils, 2-80 mass%, for example, More preferably, 5-60 mass% is mentioned. If it is less than 2 mass%, it will be difficult to dissolve the polymer compound R well in the carrier liquid C. On the other hand, if it exceeds 80% by mass, the conductivity of the entire carrier liquid C and thus the conductivity of the liquid developer becomes excessively high. An excessively high liquid developer conductivity, for example, causes a reduction in image density.

  In the present embodiment, the conductivity of the liquid developer is preferably 200 pS / cm or less, for example. Therefore, by mixing a high electric resistance aliphatic hydrocarbon into a solution obtained by dissolving the polymer compound R in the above-mentioned oils such as tall oil fatty acid (hereinafter referred to as “resin solution”). The conductivity of the entire carrier liquid C (the conductivity of the liquid developer) is preferably adjusted to 200 pS / cm or less, for example.

<Colored particles>
In the present embodiment, the pigment itself is used as the colored particles P. The liquid developer containing the pigment itself enables the non-heating type fixing process described with reference to FIGS. As a result, the pigment as the colored particles P is fixed on the recording medium with little consumption of heat energy and light energy.

  As the pigment in the present embodiment, for example, conventionally known organic pigments and inorganic pigments are used without particular limitation.

  Examples of black pigments include azine dyes such as carbon black, oil furnace black, channel black, lamp black, acetylene black, and aniline black, metal salt azo dyes, metal oxides, and composite metal oxides. Examples of yellow pigments include cadmium yellow, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, hansa yellow G, hansa yellow 10G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, and tartrazine lake. . Examples of the orange pigment include molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, and indanthrene brilliant orange GK. Examples of red pigments include Bengala, Cadmium Red, Permanent Red 4R, Resol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B. Examples of purple pigments include fast violet B and methyl violet lake. Examples of blue pigments include C.I. I. Pigment Blue 15: 3, cobalt blue, alkali blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partial chlorinated product, first sky blue, and indanthrene blue BC. Examples of the green pigment include chrome green, chromium oxide, pigment green B, and malachite green lake.

  The content of the pigment in the liquid developer is preferably 1 to 30% by mass. More preferably, it is 3 mass% or more, More preferably, it is 5 mass% or more. Moreover, More preferably, it is 20 mass% or less, More preferably, it is 10 mass% or less.

The average particle diameter of the pigment in the liquid developer, that is, the volume-based median diameter (D ₅₀ ) is preferably 0.1 to 1.0 μm. A pigment having an average particle size of less than 0.1 μm causes, for example, a reduction in image density. A pigment having an average particle diameter exceeding 1.0 μm causes, for example, a decrease in fixability. Here, the volume-based median diameter (D ₅₀ ) is generally 50% when the cumulative curve is obtained with the total volume of a group of particles whose particle size distribution is required as 100%. The particle diameter of a point.

<Dispersion stabilizer>
The liquid developer according to this embodiment may contain a dispersion stabilizer for promoting and stabilizing the dispersion of particles in the liquid developer. As a dispersion stabilizer that can be used in the present embodiment, for example, “BYK-116” manufactured by Big Chemie is suitable. In addition, “Solsperse 9000”, “Solsperse 11200”, “Solsparse 13940”, “Solspers 16000”, “Solspers 17000”, “Solspers 18000” manufactured by Lubrizol, and “Antaron (registered trademark) V-” manufactured by ISP 216 "," Antaron (registered trademark) V-220 "can also be preferably used.

  The content of the dispersion stabilizer in the liquid developer is about 1 to 10% by mass, preferably about 2 to 6% by mass.

<Polymer compound>
The polymer compound R contained in the liquid developer according to this embodiment is an organic polymer compound. As the organic polymer compound having solubility in the carrier liquid C, a material capable of increasing the viscosity of the liquid developer and suppressing the occurrence of bleeding in image formation is selected. Examples of the organic polymer compound include cyclic olefin copolymer, styrene elastomer, cellulose ether, and polyvinyl butyral. Preferably, a styrene elastomer is used as the organic polymer compound. As the polymer compound R, a single type of organic polymer compound may be used, or a plurality of types of organic polymer compounds may be used.

  In the liquid developer according to this embodiment, the organic polymer compound is dissolved in the carrier liquid C. The organic polymer compound dissolved in the carrier liquid C may be in a gel state. Depending on the type and molecular weight of the organic polymer compound, a gel-like organic polymer compound entangled with each other in the carrier liquid C can be obtained. Gel-like organic polymer compounds have relatively low fluidity. For example, when the concentration of the organic polymer compound is high, when the affinity between the organic polymer compound and the carrier liquid C is low, or when the temperature is low, a gel-like organic polymer compound is easily obtained. On the other hand, the organic polymer compound with little entanglement in the carrier liquid C becomes a solution having relatively high fluidity.

  The content of the organic polymer compound in the liquid developer is appropriately determined according to the type of the organic polymer compound. The content of the organic polymer compound is preferably 1 to 10% by mass, for example.

  If the content of the organic polymer compound is less than 1% by mass, sufficient viscosity in the liquid developer cannot be obtained, and there is a possibility that the occurrence of bleeding in image formation cannot be sufficiently suppressed. On the other hand, when the content of the organic polymer compound exceeds 10% by mass, the amount of the coating film formed by the organic polymer compound remaining on the surface of the sheet S is excessively increased, the drying property of the coating film is excessively decreased, and the adhesion of the coating film is decreased. (Tackiness) may be excessively increased, and the scratch resistance of the image may be excessively decreased.

  Hereinafter, organic polymer compounds that can be suitably used in the present embodiment will be further described.

(Cyclic olefin copolymer)
The cyclic olefin copolymer is a non-crystalline thermoplastic olefin resin having a cyclic olefin skeleton in the main chain and containing no environmental load substance, and is excellent in transparency, light weight, low water absorption, and the like. In the present embodiment, the cyclic olefin copolymer is an organic polymer compound having a main chain composed of a carbon-carbon bond and having a cyclic hydrocarbon structure in at least a part of the main chain. This cyclic hydrocarbon structure is introduced by using a compound (cyclic olefin) having at least one olefinic double bond in the cyclic hydrocarbon structure as represented by norbornene or tetracyclododecene as a monomer. Is done.

  Examples of the cyclic olefin copolymer that can be used in the present embodiment include (1) addition (co) polymer of cyclic olefin or hydrogenated product thereof, (2) addition copolymer of cyclic olefin and α-olefin, or The hydrogenated product, (3) a ring-opening (co) polymer of a cyclic olefin, or a hydrogenated product thereof.

Examples of the cyclic olefin include the following substances.
(A) cyclopentene, cyclohexene, cyclooctene;
(B) a monocyclic olefin such as cyclopentadiene or 1,3-cyclohexadiene;
(C) Bicyclo [2.2.1] hept-2-ene (norbornene), 5-methyl-bicyclo [2.2.1] hept-2-ene, 5,5-dimethyl-bicyclo [2.2. 1] Hept-2-ene, 5-ethyl-bicyclo [2.2.1] hept-2-ene, 5-butyl-bicyclo [2.2.1] hept-2-ene, 5-ethylidene-bicyclo [ 2.2.1] hept-2-ene, 5-hexyl-bicyclo [2.2.1] hept-2-ene, 5-octyl-bicyclo [2.2.1] hept-2-ene, 5- Octadecyl-bicyclo [2.2.1] hept-2-ene, 5-methylidene-bicyclo [2.2.1] hept-2-ene, 5-vinyl-bicyclo [2.2.1] hept-2-ene Ene, 5-propenyl-bicyclo [2.2.1] hept-2-ene 2 the ring of the cyclic olefin;
(D) Tricyclo [4.3.0.12,5] deca-3,7-diene (dicyclopentadiene), tricyclo [4.3.0.12,5] dec-3-ene.
(E) Tricyclo [4.4.0.12,5] undeca-3,7-diene or tricyclo [4.4.0.12,5] undeca-3,8-diene or a partially hydrogenated product thereof ( Or an adduct of cyclopentadiene and cyclohexene), which is tricyclo [4.4.0.12,5] undec-3-ene;
(F) 5-cyclopentyl-bicyclo [2.2.1] hept-2-ene, 5-cyclohexyl-bicyclo [2.2.1] hept-2-ene, 5-cyclohexenylbicyclo [2.2.1] ] A tricyclic olefin such as hepta-2-ene and 5-phenyl-bicyclo [2.2.1] hept-2-ene.
(G) Tetracyclo [4.4.0.12,5.17,10] dodec-3-ene (tetracyclododecene), 8-methyltetracyclo [4.4.0.12,5.17,10 ] Dodec-3-ene, 8-ethyltetracyclo [4.4.0.12, 5.17,10] dodec-3-ene, 8-methylidenetetracyclo [4.4.0.12,5. 17,10] dodec-3-ene, 8-ethylidenetetracyclo [4.4.0.12,5.17,10] dodec-3-ene, 8-vinyltetracyclo [4,4.0.12. 4.17,10] dodec-3-ene, 4-cyclic olefins such as 8-propenyl-tetracyclo [4.4.0.12, 5.17,10] dodec-3-ene;
(H) 8-cyclopentyl-tetracyclo [4.4.0.12,5.17,10] dodec-3-ene, 8-cyclohexyl-tetracyclo [4.4.0.12,5.17,10] dodeca -3-ene, 8-cyclohexenyl-tetracyclo [4.4.0.12, 5.17,10] dodec-3-ene, 8-phenyl-cyclopentyl-tetracyclo [4.4.0.12,5. 17,10] dodec-3-ene;
(I) Tetracyclo [7.4.13,6.01,9.02,7] tetradeca-4,9,11,13-tetraene (1,4-methano-1,4,4a, 9a-tetrahydrofluorene) , Tetracyclo [8.4.14, 7.01, 10.03,8] pentadeca-5,10,12,14-tetraene (to 1,4-methano-1,4,4a, 5,10,10a-) Oxahydroanthracene);
(J) pentacyclo [6.6.1.13,6.02,7.09,14] -4-hexadecene, pentacyclo [6.5.1.13,6.02,7.09,13] -4 -Pentadecene, pentacyclo [7.4.0.02, 7.13, 6.110, 13] -4-pentadecene; heptacyclo [8.7.0.12, 9.14, 7.111, 17.03, 8.012,16] -5-eicosene, heptacyclo [8.7.0.12,9.03,8.14,7.012,17.113, l6] -14-eicosene;
(K) A polycyclic olefin such as a tetramer of cyclopentadiene. These cyclic olefins can be used alone or in combination of two or more.

  As the above-mentioned α-olefin, an α-olefin having 2 to 20 carbon atoms, preferably 2 to 8 carbon atoms is preferable. As α-olefin, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl- 1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, Examples include 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicocene. These α-olefins can be used alone or in combination of two or more.

  In the present embodiment, there are no particular restrictions on the polymerization method of cyclic olefin, the polymerization method of cyclic olefin and α-olefin, and the hydrogenation method of the obtained polymer, and can be carried out according to known methods. .

  In the present embodiment, the structure of the cyclic olefin copolymer is not particularly limited. The structure of the cyclic olefin copolymer may be linear, branched or cross-linked, but is preferably linear.

  In the present embodiment, as the cyclic olefin copolymer, for example, a copolymer of norbornene and ethylene or a copolymer of tetracyclododecene and ethylene is preferably used. As the cyclic olefin copolymer, a copolymer of norbornene and ethylene is particularly preferable. The content of norbornene in the copolymer is preferably 60 to 82% by mass, more preferably 60 to 79% by mass, further preferably 60 to 76% by mass, and still more preferably 60 to 65% by mass. When the norbornene content is less than 60% by mass, the glass transition temperature of the cyclic olefin copolymer film becomes too low, and the film-forming property of the cyclic olefin copolymer film may be lowered. When the norbornene content exceeds 82% by mass, the glass transition temperature of the cyclic olefin copolymer coating film becomes too high, and the fixability of the pigment, that is, the image by the cyclic olefin copolymer coating film may be lowered. Moreover, the solubility of the cyclic olefin copolymer in the carrier liquid C may become excessively low.

  In this embodiment, what is marketed may be used as a cyclic olefin copolymer. For example, as a copolymer of norbornene and ethylene, "TOPAS (registered trademark) TM" (norbornene content: about 60% by mass) and "TOPAS (registered trademark) TB" manufactured by Topas Advanced Polymers GmbH (Norbornene content: about 60 mass%), “TOPAS (registered trademark) 8007” (norbornene content: about 65 mass%), “TOPAS (registered trademark) 5013” (norbornene content: about 76 mass%), “ "TOPAS (registered trademark) 6013" (norbornene content: about 76 mass%), "TOPAS (registered trademark) 6015" (norbornene content: about 79 mass%), "TOPAS (registered trademark) 6017" (norbornene content: About 82% by mass). These may be used alone or in combination of two or more depending on the situation.

(Styrene elastomer)
As the styrene-based elastomer that can be used in the present embodiment, conventionally known styrene elastomers can be used without particular limitation. Examples of the styrene elastomer include a block copolymer composed of an aromatic vinyl compound and an olefin compound or a conjugated diene compound. As a block copolymer, for example, a block having a structure represented by Chemical Formula 1 when A is a polymer block made of an aromatic vinyl compound and B is a polymer block made of an olefinic compound or a conjugated diene compound A copolymer is mentioned.

  Examples of the aromatic vinyl compound constituting the block copolymer include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,3-dimethylstyrene, 2,4- Dimethylstyrene, monochlorostyrene, dichlorostyrene, p-bromostyrene, 2,4,5-tribromostyrene, 2,4,6-tribromostyrene, o-tert-butylstyrene, m-tert-butylstyrene, p- Examples thereof include tert-butyl styrene, ethyl styrene, vinyl naphthalene, and vinyl anthracene.

  The polymer block A may be comprised from 1 type in the above-mentioned aromatic vinyl compound, and may be comprised from 2 or more types. Among these, those composed of styrene and / or α-methylstyrene give preferable physical properties to the liquid developer according to this embodiment.

  Examples of the olefin compounds constituting the block copolymer include ethylene, propylene, 1-butene, 2-butene, isobutene, 1-pentene, 2-pentene, cyclopentene, 1-hexene, 2-hexene, cyclohexene, Examples include 1-heptene, 2-heptene, cycloheptene, 1-octene, 2-octene, cyclooctene, vinylcyclopentene, vinylcyclohexene, vinylcycloheptene, and vinylcyclooctene.

  Examples of the conjugated diene compound constituting the block copolymer include butadiene, isoprene, chloroprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene.

  The polymer block B may be comprised from 1 type of the above-mentioned olefinic compound and the above-mentioned conjugated diene compound, and may be comprised from 2 or more types. Among these, those composed of butadiene and / or isoprene give preferable properties to the liquid developer according to the present embodiment.

  Examples of the block copolymer include polystyrene-polybutadiene-polystyrene triblock copolymer or hydrogenated product thereof, polystyrene-polyisoprene-polystyrene triblock copolymer or hydrogenated product thereof, polystyrene-poly (isoprene / Butadiene) -polystyrene triblock copolymer or hydrogenated product thereof, poly (α-methylstyrene) -polybutadiene-poly (α-methylstyrene) triblock copolymer or hydrogenated product thereof, poly (α-methylstyrene) A polyisoprene-poly (α-methylstyrene) triblock copolymer or a hydrogenated product thereof, poly (α-methylstyrene) -poly (isoprene / butadiene) -poly (α-methylstyrene) triblock copolymer, or Its hydrogenated product, polystyrene-polyiso Ten - polystyrene triblock copolymer, poly (alpha-methylstyrene) - polyisobutene - poly (alpha-methylstyrene) triblock copolymer.

  As the styrene elastomer used in the present embodiment, a styrene-butadiene elastomer (SBS) in which the polymer block A and the polymer block B have a structure represented by the chemical formula 2 is preferable.

  The styrene-butadiene elastomer is obtained by copolymerizing a styrene monomer and butadiene which is a conjugated diene compound. Preferred styrene monomers include styrene, α-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-ethyl styrene, 2,4-dimethyl styrene, pn-butyl styrene, p-dodecyl. Examples include styrene, p-methoxystyrene, p-phenylstyrene, and p-chlorostyrene.

  The above-mentioned styrene-butadiene elastomer has a number average molecular weight Mn in the molecular weight distribution by GPC (gel permeation chromatography), preferably in the range of 1,000 to 100,000 (see Chemical Formula 1), more preferably. Is in the range of 2,000 to 50,000. The weight average molecular weight Mw is preferably in the range of 5,000 to 1,000,000, more preferably in the range of 10,000 to 500,000. In that case, it is preferable that the weight average molecular weight Mw is in the range of 2,000 to 200,000, and preferably at least one peak is in the range of 3,000 to 150,000.

  In the above styrene-butadiene elastomer, the value of the ratio (weight average molecular weight Mw / number average molecular weight Mn) is preferably 3.0 or less, and more preferably 2.0 or less.

  The styrene content (content of polymer block A) in the styrene-butadiene elastomer described above is preferably in the range of 5 to 75% by mass (see Chemical Formula 2), more preferably 10 to 65% by mass. Is within the range. When the styrene content is less than 5% by mass, the glass transition temperature of the styrene-based elastomer film becomes too low, and the film-forming property of the styrene-based elastomer film tends to decrease. When the styrene content exceeds 75% by mass, the softening point of the styrene elastomer film becomes too high, and the fixability of the pigment, that is, the image by the styrene elastomer film tends to be lowered.

  In this embodiment, a commercially available styrene elastomer can be used. For example, as a styrene-conjugated diene block copolymer, Kuraray's “Septon” S1001, S2063, S4055, S8007 and “Hibler” 5127, 7311, Shell's “Clayton”, Asahi Kasei Chemicals' “Asuprene ( Registered trademark) "T411, T413, T437," Tufprene (registered trademark) "A, 315P, etc.," JSR TR1086 "," JSR TR2000 "," JSR TR2250 "," JSR TR2827 "manufactured by JSR; styrene-conjugated diene As a hydrogenated block copolymer, “Dynalon” 6200P, 4600P, 1320P manufactured by JSR, etc .; As a styrene-ethylene copolymer, “Index” manufactured by Dow Chemical Co., etc .; As a composition, Aron Kasei Co., Ltd. "Aron AR" made by Mitsubishi, Mitsubishi Gakusha made of "Rabalon", and the like. These may be used alone or in combination of two or more depending on the situation. “Septon” S1001, S2063, S4055, S8007 and “Hibler” 5127, 7311 manufactured by Kuraray are hydrogenated products of styrene-conjugated diene block copolymers.

(Cellulose ether)
Cellulose ether is a polymer in which a hydroxyl group in a cellulose molecule is substituted with an alkoxy group. The substitution rate is preferably 45 to 49.5%. Moreover, the alkyl part of the alkoxy group may be substituted with, for example, a hydroxyl group. The cellulose ether film is excellent in toughness and thermal stability.

  Examples of the cellulose ether that can be used in the present embodiment include alkyl celluloses such as methyl cellulose and ethyl cellulose; hydroxyalkyl celluloses such as hydroxyethyl cellulose and hydroxypropyl cellulose; hydroxyalkylalkyl celluloses such as hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, and hydroxyethyl ethyl cellulose; carboxymethyl cellulose And carboxyalkyl hydroxyalkyl cellulose such as carboxymethyl hydroxyethyl cellulose. These may be used alone or in combination of two or more. Among these, alkyl cellulose is preferable, and among the alkyl celluloses, ethyl cellulose is preferable.

  In this embodiment, what is marketed can be used as a cellulose ether. Examples of the ethyl cellulose include “Etocel (registered trademark) STD4”, “Etocel (registered trademark) STD7”, “Etocel (registered trademark) STD10” manufactured by Nisshinsei Co., Ltd., and the like. These may be used alone or in combination of two or more depending on the situation.

(Polyvinyl butyral)
The polyvinyl butyral (butyral resin: alkyl acetalized polyvinyl alcohol) that can be used in the present embodiment has a hydroxyl group, a hydrophilic vinyl alcohol unit, a butyral group, and a hydrophobic vinyl as shown in Chemical Formula 3. It is a copolymer of an acetal unit and a vinyl acetate unit having an acetyl group and having intermediate properties between a vinyl alcohol unit and a vinyl acetal unit. In the liquid developer according to the exemplary embodiment, polyvinyl butyral having a degree of butyralization (determining a ratio between a hydrophilic part and a hydrophobic part) having a film forming ability (film forming property) of 60 to 85 mol% is excellent. Is preferable. Polyvinyl butyral has a vinyl acetal unit that is soluble in a nonpolar solvent and a vinyl alcohol unit that improves the binding property to a recording medium such as paper. Therefore, it is used in both the carrier liquid C and the recording medium. It has a high affinity for it.

  It does not specifically limit as polyvinyl butyral which can be used by this embodiment. Examples of polyvinyl butyral include “Mowital (registered trademark)” B20H, B30B, B30H, B60T, B60H, B60HH, and B70H manufactured by Hoechst; “ESREC (registered trademark)” BL-1 (butyralized) manufactured by Sekisui Chemical Co., Ltd. Degree: 63 ± 3 mol%), BL-2 (same: 63 ± 3 mol%), BL-S (same: 70 mol% or more), BL-L, BH-3 (same: 65 ± 3 mol%), BM-1 (Same: 65 ± 3 mol%), BM-2 (same: 68 ± 3 mol%), BM-5 (same: 63 ± 3 mol%), BM-S; “Denkabutyral” # 2000- manufactured by Denki Kagaku Kogyo Co., Ltd. L, # 3000-1, # 3000-2, # 3000-3, # 3000-4, # 3000-K, # 4000-1, # 5000-A, # 6000-C. These may be used alone or in combination of two or more.

(Production method)
The liquid developer according to the exemplary embodiment uses a carrier liquid C, a pigment, an organic polymer compound, and, if necessary, a dispersion stabilizer such as a ball mill, a sand grinder, a dyno mill, or a rocking mill (zirconia beads or the like). It can be manufactured by sufficiently dissolving or mixing and dispersing over several minutes to several tens of hours as necessary.

The pigment is finely pulverized by the mixing and dispersion described above. As described above, the mixing and dispersion time and the number of rotations are adjusted so that the average particle diameter (D ₅₀ ) of the pigment in the liquid developer is preferably 0.1 to 1.0 μm. If the dispersion time is excessively short or the rotational speed is excessively small, the average particle diameter (D ₅₀ ) of the pigment exceeds 1.0 μm, and as described above, the fixability may be lowered. If the dispersion time is excessively long or the rotational speed is excessively large, the average particle diameter (D ₅₀ ) of the pigment becomes less than 0.1 μm, and as described above, the image density is lowered due to insufficient developability. Is caused.

  In this embodiment, after dissolving the organic polymer compound in the carrier liquid C, a liquid developer may be produced by mixing and dispersing a pigment (with a dispersion stabilizer as necessary), or Resin solution (referred to a solution obtained by dissolving an organic polymer compound in carrier liquid C) and pigment dispersion (referred to a material obtained by mixing and dispersing pigment (along with a dispersion stabilizer depending on the situation) in carrier liquid C). And a liquid developer may be produced by mixing them in an appropriate mixing ratio (mass ratio).

In order to calculate the average particle diameter (D ₅₀ ) of the pigment, the particle size distribution of the pigment is measured. The particle size distribution of the pigment is measured, for example, by the following method.

  A predetermined amount of the produced liquid developer or the prepared pigment dispersion is sampled, and diluted 10 to 100 times (volume) with the same carrier liquid C as the carrier liquid C used in the liquid developer or pigment dispersion. The particle size distribution of the pigment is measured by a flow method using a laser diffraction type particle size distribution measuring device “Mastersizer 2000” manufactured by MALVERN.

  The viscosity of the manufactured liquid developer is measured using a vibration type viscometer “VISCOMATE VM-10A-L” manufactured by CBC at a measurement temperature of 25 ° C.

(Second Embodiment)
<Fixing principle>
Hereinafter, the fixing principle according to the second embodiment will be described. The fixing principle of the second embodiment relates to the influence on the fixing rate FR given by the number in the rubbing direction. The fixing principle described in relation to the first embodiment is preferably applied to the fixing principle of the second embodiment. Therefore, the description overlapping with the description related to the first embodiment is omitted. In the following description, the same code | symbol is assigned with respect to the element similar to 1st Embodiment. The description which concerns on 1st Embodiment is used suitably with respect to the element which is not demonstrated below.

<Test example>
FIG. 11 is a schematic diagram for schematically explaining a test method for examining the influence of the number in the rubbing direction on the fixing rate FR. FIG. 11A to FIG. 11D illustrate the test conditions according to the present embodiment, respectively.

  In this test, a sheet S on which the image layer I was formed was prepared. Similar to the test described in relation to the first embodiment, the image layer I is rubbed by the rubbing plate 200. The rubbing against the image layer I was performed under the four conditions shown in FIGS. 11 (a) to 11 (d). The other test conditions are the same as those described in connection with the first embodiment.

  Under the first test condition (FIG. 11A), the image layer I was rubbed in the first test direction (from right to left). The rubbing period was 5 seconds. The number of rubbing was 80 times.

  Under the second test condition (FIG. 11B), the image layer I was rubbed in the first test direction and the second test direction (left to right) opposite to the first test direction. The total rubbing period was 5 seconds. The number of rubbing times in the first test direction and the number of rubbing times in the second test direction were 40 times, respectively.

  Under the third test condition (FIG. 11C), the image layer I was rubbed in the first test direction, the second test direction, and the third test direction (from bottom to top) orthogonal thereto. The total rubbing period was 5 seconds. The number of rubbing in the first test direction and the number of rubbing in the second test direction were 27 times, respectively. The number of rubbing times in the third test direction was 26 times.

  In the fourth test condition (FIG. 11D), the image layer I has a first test direction, a second test direction, a third test direction, and a fourth test direction (from top to bottom) opposite to the third test direction. I was rubbed. The total rubbing period was 5 seconds. The number of rubbing times in the first test direction to the fourth test direction was 20 times.

  FIG. 12 is a graph showing the fixation rate FR obtained under the test conditions described with reference to FIG. The horizontal axis of the graph in FIG. 12 indicates the number of rubbing directions described in relation to FIG. The vertical axis of the graph in FIG. 12 indicates the fixing rate FR of the image layer I on the sheet S. The calculation method of the fixing rate FR shown in FIG. 12 follows the calculation method described in relation to the first embodiment. The influence of the number in the rubbing direction on the fixing rate FR will be described with reference to FIGS. 11 and 12.

  As shown in FIG. 12, the fixing rate FR increased linearly as the rubbing direction increased. Under the first test conditions described with reference to FIG. 11A, the fixing rate FR was 56%. Under the second test conditions described with reference to FIG. 11B, the fixing rate FR was 73%. Under the third test condition described in relation to FIG. 11C, the fixing rate FR was 84%. Under the third test condition described in relation to FIG. 11D, the fixing rate FR was 94%.

  From the graph shown in FIG. 12, it can be seen that an increase in the rubbing direction results in a high fixing rate FR in a relatively short period of rubbing.

<Fixing device>
FIG. 13 is a plan view schematically showing a fixing device 300A formed so as to perform the rubbing operation in the three directions shown in FIG. The fixing device 300A will be described with reference to FIGS.

  The fixing device 300A includes the rubbing roller 310 described in relation to the first embodiment. The rubbing roller 310 includes a cylindrical contact cylinder 311 that contacts the image layer I and a shaft 312 that supports the contact cylinder 311. The shaft 312 includes a first end 315 and a second end 316 opposite to the first end 315.

  The fixing device 300 </ b> A includes a gear 321 attached to the second end 316 of the shaft 312 and a motor 330 coupled to the gear 321. The motor 330 rotates the shaft 312 via the gear 321. As a result, the contact cylinder 311 rotates integrally with the shaft 312. In the present embodiment, the motor 330 is exemplified as the second drive source. The gear 321 is exemplified as a transmission element.

  The fixing device 300 </ b> A includes a pair of thrust bearings 317 that rotatably support the shaft 312. The pair of thrust bearings 317 are disposed between the first end 315 of the shaft 312 and the contact cylinder 311 and between the gear 321 and the contact cylinder 311, respectively. The thrust bearing 317 allows not only rotation of the shaft 312 but also displacement of the shaft 312 in the axial direction.

  Fixing device 300 </ b> A includes a cam gear 318 disposed so as to come into contact with first end 315 of shaft 312, and a motor 319 connected to cam gear 318. The cam gear 318 disposed eccentrically with respect to the shaft 312 includes a circumferential surface 361 that meshes with the motor 319 and a pressing surface 362 that contacts the first end 315 of the shaft 312. The pressing surface 362 gradually increases in thickness toward the second end 316 of the shaft 312. The vector shown in FIG. 13 exemplifies a first direction D1 that means the conveyance direction of the sheet S. The motor 319 rotates the cam gear 318 eccentrically with respect to the shaft 312. As a result, the shaft 312 and the contact cylinder 311 are pressed and displaced in the first intersecting direction T1 orthogonal to the first direction D1. In the present embodiment, the cam gear 318 is exemplified as a cam element. The motor 319 is exemplified as the first drive source.

  The fixing device 300 </ b> A includes a coil spring 363 disposed adjacent to the second end 316 of the shaft 312. The coil spring 363 biases the gear 321 attached to the second end 316 in the second crossing direction T2 opposite to the first crossing direction. In the present embodiment, the coil spring 363 is exemplified as the biasing element.

  FIG. 14 shows the reciprocating movement of the rubbing roller 310 by the motor 319. 14 is a schematic plan view of a fixing device 300A having a contact cylinder 311 that is close to the cam gear 318. FIG. 14 is a schematic plan view of a fixing device 300A having a contact cylinder 311 spaced from the cam gear 318. FIG. The fixing device 300 </ b> A is further described with reference to FIGS. 11, 13, and 14.

  As described above, the cam gear 318 is arranged eccentrically with respect to the shaft 312. In FIG. 14, the amount of eccentricity between the cam gear 318 and the shaft 312 is represented using the symbol “e”. As shown in the upper diagram of FIG. 14, when the first end 315 of the shaft 312 comes into contact with the thin portion of the cam gear 318, the contact cylinder 311 approaches the cam gear 318. As shown in the lower part of FIG. 14, when the first end 315 of the shaft 312 comes into contact with the thick part of the cam gear 318, the contact cylinder 311 is separated from the cam gear 318. In FIG. 14, the displacement amount of the contact cylinder 311 in the first intersecting direction T1 or the second intersecting direction T2 is represented by using a symbol “M”.

  As shown in the lower diagram of FIG. 14, when the contact cylinder 311 is separated from the cam gear 318, the coil spring 363 is compressed. Thereafter, when the first end 315 of the shaft 312 moves on the pressing surface 362 of the cam gear 318 and the contact position between the first end 315 and the pressing surface 362 of the cam gear 318 moves to the thick part of the cam gear 318, The coil spring 363 extends. Thus, the coil spring 363 properly maintains contact between the first end 315 of the shaft 312 and the cam gear 318. As a result, the reciprocation of the contact cylinder 311 due to the rotation of the cam gear 318 by the motor 319 is appropriately achieved.

  FIG. 15 is a schematic side view of the fixing device 300A and the conveying device that fixes the image layer I on the sheet S in cooperation with the fixing device 300A. FIG. 15A generally shows the fixing device 300A and the conveying device. FIG. 15B is an enlarged view around the rubbing roller 310. The fixing device 300 </ b> A is further described with reference to FIGS. 4, 13, and 15.

  The conveying device includes an upstream conveying device 410A disposed upstream of the fixing device 300A and a downstream conveying device 420A disposed downstream of the fixing device 300A. The upstream conveying device 410A and the downstream conveying device 420A are exemplified as conveying elements that convey the sheet S, as in the first embodiment.

  The transport device includes an intermediate transport unit 450 disposed between the upstream transport device 410A and the downstream transport device 420A. In the present embodiment, in addition to the upstream transport device 410A and the downstream transport device 420A, the intermediate transport unit 450 is also exemplified as a transport element.

  The upstream conveyance device 410A includes an upper roller 411 and a lower roller 412 as in the first embodiment. The upstream conveyance device 410A includes an upper guide plate 461 for stabilizing the conveyance of the sheet S to the intermediate conveyance unit 450, and a lower guide plate 462 disposed below the upper guide plate 461. The sheet S conveyed by the upper roller 411 and the lower roller 412 is guided by the upper guide plate 461 and the lower guide plate 462 and supplied to the intermediate conveyance unit 450.

  The downstream conveyance device 420A includes an upper roller 421 and a lower roller 422 as in the first embodiment. The downstream conveyance device 420A includes an upper guide plate 463 for stabilizing the conveyance of the sheet S from the intermediate conveyance unit 450 to the nip portion formed between the upper roller 421 and the lower roller 422, and the upper guide plate 463. And a lower guide plate 464 disposed below. The sheet S conveyed by the intermediate conveyance unit 450 is guided by the upper guide plate 463 and the lower guide plate 464, and is supplied to the nip portion between the upper roller 421 and the lower roller 422.

  FIG. 15 schematically shows a contact cylinder 311 and a shaft 312 of the rubbing roller 310 as the fixing device 300A. Similar to the first embodiment, the contact tube 311 includes a substantially cylindrical elastic layer 313 that surrounds the peripheral surface of the shaft 312 and a non-woven fabric layer 314 that covers the outer peripheral surface of the elastic layer 313. The elastic layer 313 is formed using, for example, a sponge or another elastic material having a relatively high flexibility. Nonwoven fabric layer 314 is formed using, for example, a nonwoven fabric of the type described in connection with FIG.

  Intermediate conveyance unit 450 includes drive roller 451, driven roller 452, and endless belt 453 extending between drive roller 451 and driven roller 452. The sheet S is sent out on the endless belt 453 from the upstream conveying device 410A. The driving roller 451 rotates the endless belt 453 and then conveys the sheet S toward the downstream conveying device 420A. The driven roller 452 rotates according to the rotation of the endless belt 453. The direction of the vector shown in FIG. 15 is exemplified as the first direction that means the conveyance direction of the sheet S. Further, the magnitude of the vector in FIG. 15 is exemplified as a first speed V <b> 1 that means the conveyance speed of the sheet S. In the present embodiment, the endless belt 453 is exemplified as a transport belt.

  The intermediate transport unit 450 includes a backup roller 340A and a cylinder device 350A connected to the backup roller 340A. The cylinder device 350A brings the backup roller 340A into contact with the rubbing roller 310. In the present embodiment, the cylinder device 350A is exemplified as a separation / contact mechanism. Alternatively, another mechanism that can separate the backup roller 340A from the rubbing roller 310 may be used as the separation mechanism.

  The cylinder device 350 </ b> A includes an outer shell body 353 and a rod 354 formed so as to be able to appear and retract with respect to the outer shell body 353, similarly to a commercially available cylinder device. The rod 354 includes a distal end portion that rotatably supports the backup roller 340A. The rod 354 is pushed out of the outer shell 353 by, for example, a working fluid (for example, oil or air) supplied into the outer shell 353. As a result, the backup roller 340 </ b> A is displaced toward the rubbing roller 310. The backup roller 340A displaced toward the rubbing roller 310 presses the endless belt 453 against the rubbing roller 310. Thus, the peripheral surface of the rubbing roller 310 is deformed and becomes the upper nip surface N1 along the upper surface of the sheet S passing through the fixing device 300A, as in the first embodiment. Further, the outer surface of the endless belt 453 deformed along the peripheral surface of the backup roller 340A becomes a lower nip surface N2. In the present embodiment, the upper nip surface N1 that contacts the image (image layer I) formed on the upper surface of the sheet S is exemplified as the contact surface. Further, the backup roller 340A and the endless belt 453 are exemplified as the press contact portion.

  The sheet S conveyed by the intermediate conveyance unit 450 passes between the endless belt 453 and the rubbing roller 310. The motor 330 described with reference to FIG. 13 rotates the rubbing roller 310 so that the upper nip surface N1 moves in the first direction D1 at a second speed V2 different from the first speed V1. In the present embodiment, the second speed V2 is set larger than the first speed V1. Alternatively, the second speed V2 may be smaller than the first speed V1.

  As described with reference to FIG. 13, the rotation of the cam gear 318 causes the upper nip surface N1 to reciprocate in the first intersecting direction T1 and the second intersecting direction T2. Further, the sliding on the image layer I in the first direction D1 is achieved by the speed difference between the sheet S and the upper nip surface N1 in the first direction D1. In the present embodiment, the motor 330 moves the upper nip surface N1 in the first direction D1. Alternatively, the motor 330 may move the upper nip surface N1 in the second direction opposite to the first direction D1. Further, alternatively, the motor 330 and the gear 321 may be removed from the fixing device 300A. At this time, the rubbing against the image layer I is achieved by the reciprocating movement of the contact tube 311 in the first intersecting direction T1 and the second intersecting direction T2. In this case, the shaft 312 preferably supports the contact cylinder 311 in a rotatable manner.

  FIG. 16 is a schematic side view of the fixing device 300 </ b> A and the conveyance device after the sheet S has passed through the intermediate conveyance unit 450. The fixing device 300A and the conveying device are further described with reference to FIGS.

  The upstream transfer device 410A includes a switch lever 465. The switch lever 465 includes a rotating shaft 466 disposed adjacent to the lower roller 412 and an arm 467 extending from the rotating shaft 466. The arm 467 has a reference position (see FIG. 16) that crosses the conveyance path PS defined by the upper guide plate 461 and the lower guide plate 462 downstream of the nip portion between the upper roller 411 and the lower roller 412. It rotates between an inclined position (see FIG. 15A) inclined with respect to the reference position.

  The arm 467 at the reference position is rotated to an inclined position by the leading edge of the sheet S fed by the upper roller 411 and the lower roller 412. A biasing element (not shown) such as a torsion coil spring is attached to the rotating shaft 466. The biasing element biases the switch lever 465 to return the arm 467 to the reference position. Thus, when the conveyance of the sheet S from the upstream conveyance device 410A to the intermediate conveyance unit 450 is completed, the arm 467 is returned to the reference position by the biasing element.

  When the arm 467 reaches the inclined position, the switch lever 465 outputs a first trigger signal to a fluid control device (not shown) that controls the flow of working fluid into and out of the outer shell 353 of the cylinder device 350A. Based on the first trigger signal, the fluid control device causes the working fluid to flow into the outer shell body 353 and causes the rod 354 to extend from the outer shell body 353. As a result, the backup roller 340A approaches the rubbing roller 310. When the arm 467 reaches the reference position, the switch lever 465 outputs a second trigger signal to the fluid control device. The fluid control device discharges the working fluid from the outer shell 353 based on the second trigger signal, and the rod 354 is immersed in the outer shell 353. As a result, as shown in FIG. 16, the backup roller 340 </ b> A and the endless belt 453 are separated from the rubbing roller 310. Thus, unnecessary rubbing between the endless belt 453 and the rubbing roller 310 is suppressed.

  The fixing device 300A according to the second embodiment and the conveying devices (upstream conveying device 410A, intermediate conveying unit 450, and downstream conveying device 420A) responsible for conveying the sheet S to the fixing device 300A will be described in relation to the first embodiment. Instead of the fixing device 300 and the conveying device, the color printer 1 described in relation to FIGS. 8 to 10 is preferably incorporated.

(Third embodiment)
<Fixing device>
17 and 18 are side views schematically showing a fixing device and a conveying device according to the third embodiment. Hereinafter, features different from those of the second embodiment will be described. Therefore, the description overlapping with the description related to the second embodiment is omitted. In the following description, the same code | symbol is assigned with respect to the element similar to 2nd Embodiment. The description according to the second embodiment is preferably used for elements not described below. A fixing device and a conveying device according to the third embodiment will be described with reference to FIGS. 3, 17, and 18.

  The conveying device includes an upstream conveying device 410A disposed upstream of the fixing device 300A and a downstream conveying device 420A disposed downstream of the fixing device 300A. The upstream conveying device 410A and the downstream conveying device 420A are exemplified as conveying elements that convey the sheet S, as in the second embodiment.

  The transport device includes an intermediate transport unit 450B disposed between the upstream transport device 410A and the downstream transport device 420A. In the present embodiment, in addition to the upstream conveyance device 410A and the downstream conveyance device 420A, an intermediate conveyance unit 450B is also exemplified as a conveyance element.

  The intermediate transport unit 450B includes a driving roller 451, a driven roller 452, and an endless belt 453 extending between the driving roller 451 and the driven roller 452. The sheet S is sent out on the endless belt 453 from the upstream conveying device 410A. The driving roller 451 rotates the endless belt 453 and then conveys the sheet S toward the downstream conveying device 420A. The driven roller 452 rotates according to the rotation of the endless belt 453.

  The intermediate transport unit 450B includes an upstream backup roller 343 and a downstream backup roller 344 disposed between the driving roller 451 and the driven roller 452. The intermediate transport unit 450B further includes a frame 349 that rotatably supports the upstream backup roller 343 and the downstream backup roller 344. The frame 349 causes the endless belt 453 to approach the rubbing roller 310 or to be separated from the rubbing roller 310 by a separation / contact mechanism similar to the cylinder device 350A described in relation to the second embodiment. The proximity and separation of the endless belt 453 with respect to the rubbing roller 310 are controlled by a switch lever 465 provided in the upstream conveying device 410A, as in the second embodiment. Also, the rubbing roller 310 applies rubbing in three directions to the image layer I on the sheet S by the mechanism described in relation to the second embodiment. In the present embodiment, the upstream backup roller 343 and the downstream backup roller 344 play the same role as the backup roller 340A described in relation to the second embodiment.

  The intermediate transport unit 450B includes an upstream holding roller 345 and a downstream holding roller 346 disposed upstream of the rubbing roller 310. The upstream holding roller 345 is disposed corresponding to the upstream backup roller 343. The downstream holding roller 346 is disposed corresponding to the downstream backup roller 344.

  As the switch lever 465 moves to the inclined position, the upstream backup roller 343 presses the endless belt 453 against the upstream holding roller 345. Further, the downstream backup roller 344 presses the endless belt 453 against the downstream holding roller 346 in accordance with the movement of the switch lever 465 to the inclined position. As a result, the endless belt 453 between the upstream backup roller 343 / upstream holding roller 345 and the downstream backup roller 344 / downstream holding roller 346 is pressed against the circumferential surface of the rubbing roller 310. Thus, the rubbing roller 310 defines a travel path of the endless belt 453 that is curved toward the frame 349. As a result, a relatively long rubbing time between the rubbing roller 310 and the image layer I on the sheet S is ensured. This contributes favorably to the improvement of the fixing rate FR as described with reference to FIG.

  While the rubbing roller 310 is rubbing the image layer I on the sheet S, the sheet S is between the upstream backup roller 343 and the upstream holding roller 345 and between the downstream backup roller 344 and the downstream holding roller 346. Properly held. As described in relation to the second embodiment, the rubbing roller 310 is rubbed back and forth also in a direction orthogonal to the conveyance direction of the sheet S. Nipping of the sheet S by the upstream backup roller 343, the upstream holding roller 345, the downstream backup roller 344, and the downstream holding roller 346 is a conveyance failure of the sheet S due to reciprocal rubbing in a direction orthogonal to the conveyance direction of the sheet S. Suppress.

  In the present embodiment, the sheet S is sandwiched between the upstream backup roller 343, the upstream holding roller 345, the downstream backup roller 344, and the downstream holding roller 346. Alternatively, the sheet S may be sandwiched only by the upstream backup roller 343 and the upstream holding roller 345. Further alternatively, the sheet S may be sandwiched only by the downstream backup roller 344 and the downstream holding roller 346.

(Fourth embodiment)
<Rubbing roller>
FIG. 19 schematically shows a rubbing roller described in relation to the fourth embodiment. FIG. 19A is a schematic cross-sectional view of the rubbing roller. FIG. 19B is a schematic plan view of the rubbing roller. The rubbing roller described in relation to the fourth embodiment is preferably applied in place of the rubbing roller 310 shown in the above-described embodiment.

  In the present embodiment, the rubbing roller 310C includes a hard shaft 312C (for example, a metal shaft) and a non-woven fabric band 314C wound spirally around the peripheral surface of the shaft 312C. Nonwoven fabric band 314C may be formed, for example, from the nonwoven fabric described in connection with FIG.

  In the present embodiment, the backup roller 340C is formed of an elastic material that is softer than the shaft 312C. When the backup roller 340C is pressed against the shaft 312C, the backup roller 340C is elastically deformed, and an appropriate nip portion is formed between the backup roller 340C and the rubbing roller 310C. By the fixing principle related to the above-described embodiment, the sheet S passing between the backup roller 340C and the rubbing roller 310C is rubbed. Thus, fixing of the image layer I on the sheet S is preferably achieved.

  The present invention can be applied to various image forming apparatuses such as a printer, a copier, a facsimile machine, and a multifunction machine having these functions.

1. Color printer (image forming device)
2. Image forming unit 5 Fixing unit (fixing device)
200 ······························ Rubbing plate
220 ... Nonwoven fabric 300 ... Fixing device 311 ... Contact cylinder (rubbing) element)
312, 312 C ...... Shaft 314 ............ Nonwoven fabric layer (nonwoven fabric)
315 ... 1st end 316 ... 2nd end 318 ... Cam gear (cam element)
319 ... motor (drive source: first drive source)
321 ......... Gear (Transmission element)
330 ........... motor (drive source: second drive source)
340, 340A, 340C ... backup roller 341 ... ... support cylinder (pressure contact part)
343 ... Upstream backup roller 344 ... Downstream backup roller 345 ... Upstream holding Roller 346 ... downstream holding roller 350A ... cylinder device (separation mechanism)
363 ..... coil spring (biasing element)
410 ..... Upstream transfer device (transfer element)
420 ... downstream transport device (transport element)
453 ... Endless belt (conveyor belt)
C ... Carrier liquid D1 ... First direction D2 ...・ Second direction I ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Image layer (image)
N1 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Upper nip surface (contact surface)
P ... Colored particle R ... Polymer compound S ...・ ・ ・ Seat T1 ・ ・ ・ ・ ・ ・ ・ ・ ・ First crossing direction T2 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Second crossing direction V1 ・ ・ ・ ・ ・ ・..... First speed V2 ..... Second speed

Claims (4)

A transport element for transporting the sheet;
An image forming unit that forms an image on the sheet using a liquid developer;
A fixing device for fixing the image on the sheet,
The fixing device includes a rubbing element that rubs the image on the sheet and fixes the image in a non-heated manner,
The liquid developer includes colored particles for coloring the image, a carrier liquid in which the colored particles are dispersed, and a polymer compound dissolved or swollen in the carrier liquid,
The image forming apparatus, wherein the polymer compound covers the colored particles on the sheet.   The image forming apparatus according to claim 1, wherein the polymer compound forms a film that protects the image layer formed of the colored particles from rubbing by the rubbing element.   The image forming apparatus according to claim 1, wherein the polymer compound is at least one selected from the group consisting of a cyclic olefin copolymer, a styrene elastomer, a cellulose ether, and polyvinyl butyral. The image forming apparatus according to claim 3, wherein the content of the polymer compound in the liquid developer is 1 to 10% by mass .

Images