Patent ID: 12227001

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the invention will be described in detail with reference to the drawings. For convenience of explanation, a direction along an arrow H shown inFIG.1is a vertical direction of an image forming apparatus10, a direction along an arrow W is a width direction of the image forming apparatus10, and a direction along an arrow D is a front-back direction of the image forming apparatus10.

FIG.1shows a case where the image forming apparatus10forms an ink image on a recording medium P by an ink-jet method as an example. The image forming apparatus10includes an image forming unit12, a transport unit14, and a fixing device90.

Hereinafter, the image forming unit12, the transport unit14, and the fixing device90of the image forming apparatus10will be described, and then a transfer cylinder50as an example of a cylinder member will be described.

Image Forming Unit12

As shown inFIG.1, the image forming unit12has a function of forming an ink image on the recording medium P. Specifically, the image forming unit12includes a transfer belt30as an example of an intermediate transfer body, two rolls22, an opposing roll24as an example of a rotating member, a pressure-sensitive adhesive layer forming device26, a particle supply device18, a discharge head20, a transfer body40, and a cleaner28.

The transfer belt30is formed in an endless shape and is wound around the two rolls22, the opposing roll24, and a support roll25so as to have an inverted triangular posture in a case where the transfer belt30is viewed from the front-back direction. The transfer belt30has a belt shape, and is configured to circumferentially move in a direction of an arrow A by rotationally driving at least one of the two rolls22.

The pressure-sensitive adhesive layer forming device26, the particle supply device18, the discharge head20, the transfer body40, and the cleaner28are disposed in this order on an outer circumferential surface side of the transfer belt30from an upstream side of the transfer belt30in a circumferential direction (hereinafter, referred to as “belt circumferential direction”).

The pressure-sensitive adhesive layer forming device26is disposed at one end (left side in the figure) in the width direction of the apparatus in a horizontal portion of the transfer belt30having the inverted triangular posture. The pressure-sensitive adhesive layer forming device26contains a pressure-sensitive adhesive inside, and is configured to form a pressure-sensitive adhesive layer (not shown) by applying a pressure-sensitive adhesive to an outer circumferential surface of the transfer belt30that circumferentially moves. As the pressure-sensitive adhesive, for example, glue, an organic solvent, or the like may be used.

The particle supply device18is disposed on a downstream side (right side in the figure) in the belt circumferential direction with respect to the pressure-sensitive adhesive layer forming device26in the horizontal portion of the transfer belt30. The particle supply device18contains ink-accepting particles16capable of accepting ink droplets, and is configured to supply the ink-accepting particles16to the transfer belt30on which the pressure-sensitive adhesive layer is formed.

That is, the ink-accepting particles16supplied on the transfer belt30by the particle supply device18are adhered to the pressure-sensitive adhesive layer by a pressure-sensitive adhesive force of the pressure-sensitive adhesive layer to form an ink-accepting particle layer16A on the transfer belt30.

The discharge head20is disposed on a downstream side (right side in the figure) in the belt circumferential direction with respect to the particle supply device18in the horizontal portion of the transfer belt30. A plurality of the discharge heads20are provided so as to form an ink image for each color. In the present exemplary embodiment, the discharge heads20having four colors of yellow (Y), magenta (M), cyan (C), and black (K) are provided. InFIG.1, alphabetic characters Y, M, C, and K are added after the reference numeral20corresponding to each of the above colors.

Further, the discharge head20of each color is configured to discharge ink droplets from a nozzle (not shown) onto the ink-accepting particle layer16A by a known method such as a thermal method and a piezoelectric method to form an ink image based on image data. That is, the ink droplets discharged from the discharge head20of each color are configured to form an ink image by being accepted by the ink-accepting particle layer16A.

As described above, the transfer belt30functions as a holding body that holds the formed image.

The transfer body40is disposed on a lower side of the transfer belt30. As shown inFIG.2, the transfer body40has a transfer cylinder50disposed such that an axial direction is the same as an axial direction of the opposing roll24, and a sliding member60disposed close to the transfer cylinder50. The transfer cylinder50is disposed to face the transfer belt30, and forms a nipping region T in which the transfer belt30is interposed with the opposing roll24therebetween. That is, the opposing roll24forms the nipping region T, which is a transfer position, by pressing the transfer belt30from the inside. The details of the sliding member60will be described later.

In the present exemplary embodiment, the ink image formed in the ink-accepting particle layer16A is transported to the nipping region T by circumferential movement of the transfer belt30, and the recording medium P is transported to the nipping region T by the transport unit14. Then, the transfer cylinder50transfers the ink image to the recording medium P by interposing and pressing the recording medium P and the ink image transported to the nipping region T between the transfer cylinder50and the transfer belt30.

InFIG.1, the transport direction of the recording medium P is indicated by an arrow X. Further, in the nipping region T, when the recording medium P and the ink image are interposed and pressed between the transfer cylinder50and the transfer belt30, the recording medium P and the ink image may be heated by the transfer cylinder50. Further, a recess54, which is a concave portion for accommodating a gripper36and a support member38, which will be described later, is formed on a part of the outer circumferential surface of the transfer cylinder50.

The configuration of the transfer body40in the present exemplary embodiment will be described with reference to the perspective diagram ofFIG.2. As shown inFIG.2, a pair of sprockets32are provided on both ends of the transfer cylinder50in the axial direction. The pair of sprockets32are disposed coaxially with the transfer cylinder50, and are configured to rotate integrally with the transfer cylinder50. The transfer cylinder50is configured to be rotationally driven by a drive unit (not shown). Chains34are wound around the pair of sprockets32.

Further, the sliding member60functions as an imparting portion that imparts a transport load to the recording medium P that is transported to the transfer position at which the image on the transfer belt30is transferred to the recording medium P. Specifically, the sliding member60is disposed in close proximity without coming into contact with the surface of the transfer cylinder50, and is configured to slide with respect to the recording medium transported. Here, sliding means a state where two objects are moving while touching each other.

Further, the fact that the sliding member60and the transfer cylinder50are disposed close to each other means that the sliding member60and the transfer cylinder50do not come into direct contact with each other while the recording medium P is not transported, and in a case where the recording medium P is transported in a floating state without being in close contact with the transfer cylinder50, the recording medium P and the sliding member60are disposed at an interval such that the recording medium P and the sliding member60come into contact with each other. However, in the case where the recording medium P is thin and is in close contact with the transfer cylinder50, the interval between the sliding member60and the transfer cylinder50may be set such that the sliding member60does not come into contact with the recording medium P.

As shown inFIG.1, the cleaner28is disposed on the downstream side in the belt circumferential direction with respect to the nipping region T and on the upstream side in the belt circumferential direction with respect to the pressure-sensitive adhesive layer forming device26. The cleaner28includes a blade28A that is in contact with an outer circumferential surface of the transfer belt30. The cleaner28is configured to remove the pressure-sensitive adhesive layer, the ink-accepting particles16, ink, and other foreign substances (for example, in a case where the recording medium P is paper, paper dust, or the like) remaining on the transfer belt30after passing through the nipping region T, with the blade28A as the transfer belt30circumferentially moves.

The opposing roll24is configured to be movable between a contact position that comes into contact with the transfer cylinder50and a separation position that is separated from the transfer cylinder50by a transfer movement mechanism (not shown) using a cam or the like. Specifically, the opposing roll24is, for example, always pressed or pulled to the contact position by an elastic force of an elastic member such as a spring, and is configured to move to the separation position against the elastic force by the transfer movement mechanism.

The support roll25for supporting the transfer belt30is disposed on the upstream side of the opposing roll24in the transport direction. By moving the position where the support roll25is disposed closer to or farther from the opposing roll24, it is possible to adjust the pressure and area of the contact region between the transfer belt30and the transfer cylinder50.

As described above, the transfer cylinder50has a substantially circular cross section, and the recess54for accommodating the gripper36is provided in a direction substantially orthogonal to the rotation direction. Then, the transfer cylinder50transfers the image on the transfer belt30to the recording medium P transported by the transport unit14by interposing the recording medium P transported by the transport unit14between the transfer cylinder50and the transfer belt30. In addition, substantially orthogonal means a state where an angle formed by two directions is in a range of 85 to 95 degrees.

Fixing Device90

As shown inFIG.1, the fixing device90is a device for fixing the ink image transferred to the recording medium P to the recording medium P. Specifically, the fixing device90has a pressurizing body42disposed on the downstream side of the transport unit14in the transport direction of the recording medium P, and a heating roll92.

The configuration of the fixing device90in the present exemplary embodiment will be described with reference to the perspective diagram ofFIG.3. As shown inFIG.3, the pressurizing body42has a pressurizing roll44disposed such that an axial direction of the pressurizing roll44is the same as an axial direction of the transfer cylinder50, and a pair of sprockets48are provided on both ends of the pressurizing roll44in the axial direction. The pair of sprockets48are disposed coaxially with the pressurizing roll44, and are configured to rotate integrally with the pressurizing roll44. The chains34described above are wound around the pair of sprockets48.

As shown inFIG.1, the heating roll92and the pressurizing roll44are disposed side by side in the vertical direction. That is, the heating roll92is disposed on the upper side of the pressurizing roll44. The heating roll92has a heating source90A (seeFIG.1) such as a halogen lamp inside. In the following, the position where the recording medium P is interposed between the heating roll92and the pressurizing roll44is referred to as a nipping position NP.

The heating roll92is configured to be movable between a contact position that comes into contact with the pressurizing roll44and a separation position that is separated from the pressurizing roll44by a fixing movement mechanism (not shown) using a cam or the like. Specifically, the heating roll92is, for example, always pressed or pulled to the contact position by an elastic force of an elastic member such as a spring, and is configured to move to the separation position against the elastic force by the fixing movement mechanism. The heating roll92is configured to nip the recording medium P with the pressurizing roll44at the contact position.

In the present exemplary embodiment, the heating roll92is rotationally driven and the pressurizing roll44is driven to rotate, but both the heating roll92and the pressurizing roll44may be rotationally driven. Further, a recess46for accommodating the gripper36and the support member38, which will be described later, is formed on a part of the outer circumferential surface of the pressurizing roll44.

Transport Unit14

As shown inFIGS.1to3, the transport unit14has a function of transporting the recording medium P and passing the recording medium P through the nipping region T and the nipping position NP. The transport unit14has a pair of chains34and a gripper36. The pair of chains34are an example of a driving force transmission member, and the gripper36is an example of a grasping portion that holds a tip portion of the recording medium P. InFIG.1, the chains34and the gripper36are shown in a simplified manner. In this way, the transport unit14transports the recording medium P in a state where the tip of the recording medium P is grasped by the gripper36which is a grasping portion.

As shown inFIG.1, the pair of chains34are each formed in an annular shape. Then, as shown inFIGS.2and3, the pair of chains34are disposed at an interval in a depth direction of the apparatus. That is, the pair of chains34are wound around a pair of sprockets32coaxially provided on the transfer cylinder50and a pair of sprockets48coaxially provided on the pressurizing roll44, respectively.

In a case where the transfer cylinder50is rotationally driven by a drive unit (not shown), the pair of sprockets32are also integrally rotationally driven in a rotation direction B (arrow B direction), such that the chains34circumferentially move in a circumferential direction C (arrow C direction). Further, the pressurizing roll44is driven and rotated as a result. That is, a rotational driving force of the transfer cylinder50is transmitted to the pressurizing roll44by the pair of chains34that circumferentially move in the circumferential direction C (seeFIG.1).

Further, as shown inFIGS.2and3, the support member38to which the gripper36is attached is bridged to the pair of chains34along the depth direction of the apparatus. In the present exemplary embodiment, three support members38are provided in the pair of chains34, and each support member38is fixed to the pair of chains34at a predetermined interval along the circumferential direction (circumferential direction C) of the chain34.

Further, a plurality of grippers36are attached side by side to each support member38at predetermined intervals along the depth direction of the apparatus. That is, each gripper36is attached to the chain34via each support member38. Each gripper36has a holding function of holding the tip portion of the recording medium P.

Specifically, as shown inFIG.4, the gripper36has a plurality of claws36A and a plurality of claw bases36B. The gripper36is configured to hold the recording medium P by interposing the tip portion of the recording medium P between each claw36A and each claw base36B. Therefore, the gripper36is an example of a holding portion that holds the recording medium P in a thickness direction.

Further, the gripper36is configured to hold the tip portion of the recording medium P from the downstream side of the recording medium P in the transport direction. The gripper36is configured such that, for example, the claw36A is pressed against the claw base36B by a spring or the like, and the claw36A is separated from the claw base36B by the action of a cam or the like.

As described above, in the transport unit14, the tip portion of the recording medium P sent from an accommodating unit (not shown) is held by the gripper36. Then, in the transport unit14, the chain34circumferentially moves in the circumferential direction C in a state where the gripper36holds the tip portion of the recording medium P, such that the gripper36is moved to transport the recording medium P, and recording medium P passes through the nipping region T together with the gripper36while the recording medium P is held by the gripper36.

The pair of chains34are composed of a length that is an integral multiple of the outer circumferences of the sprocket32in the transfer body40and the sprocket48in the pressurizing body42, respectively. The three support members38are provided at locations on the chains34corresponding to the positions of the recess54of the transfer cylinder50and the recess46of the pressurizing roll44, respectively. Therefore, in a case where the gripper36reaches the transfer cylinder50when moving along with the rotation of the chain34, the gripper36moves integrally with the transfer cylinder50in a state of being accommodated in the recess54of the transfer cylinder50. Similarly, in a case where the gripper36reaches the pressurizing roll44when moving along with the rotation of the chain34, the gripper36moves integrally with the pressurizing roll44in a state of being accommodated in the recess46of the pressurizing roll44.

Here, the transport unit14in the present exemplary embodiment is configured to transport the recording medium P toward the nipping position NP while the gripper36holds the tip portion of the recording medium P in a state where the heating roll92is located at a separation position. The transport unit14is configured to release the holding of the tip portion of the recording medium P in a case where the recording medium P is transported to the nipping position NP.

That is, the transport unit14is configured to release the holding of the tip portion of the recording medium P after the gripper36passes through the nipping position NP. At this time, the pressurizing roll44is configured to maintain a rotated state, in other words, a state in which the chain34circumferentially moves.

Further, the fact that the recording medium P is transported to the nipping position NP is detected by the time after detecting the tip of the recording medium P, for example, by a detection unit provided on the upstream side of the nipping position NP in the transport direction detects it. The detection target of the detection unit may be the support member38or the gripper36other than the tip of the recording medium P.

Further, the heating roll92is configured to start moving from the separation position to the contact position after the gripper36passes through the nipping position NP and after the holding of the tip portion of the recording medium P by the gripper36is released, and nip the recording medium P transported to the nipping position NP with the pressurizing roll44therebetween. The heating roll92is configured to start rotating and transport the recording medium P in a state where the recording medium P is interposed between the heating roll92and the pressurizing roll44.

The heating roll92may start moving from the separation position to the contact position before the holding of the tip portion of the recording medium P by the gripper36is released, and it may be configured such that the interposing the recording medium P between the heating roll92and the pressurizing roll44is completed after the holding of the tip portion of the recording medium P by the gripper36is released.

As described above, in the fixing device90, it is configured such that the ink image transferred to the recording medium P is fixed to the recording medium P by heating and pressurizing the recording medium P while transporting the recording medium P with the recording medium P interposed between the heating roll92and the pressurizing roll44.

Transfer Cylinder50

Next, the transfer cylinder50will be described. A perspective diagram of the transfer cylinder50is shown inFIG.5, and a cross-sectional diagram of the transfer cylinder50is shown inFIG.6.

As shown inFIGS.5and6, the transfer cylinder50as an example of a cylinder member has a cylinder main body52and a sheet-shaped sheet member100wound around the cylinder main body52. In the following, an axial direction, a radial direction, and a circumferential direction of the cylinder main body52may be simply expressed as “axial direction”, “radial direction”, and “circumferential direction”.

Further, in the following, an upstream of the transfer cylinder50in the rotation direction (arrow B direction) may be simply referred to as “upstream”, and a downstream of the transfer cylinder50in the rotation direction (arrow B direction) may be simply referred to as “downstream”. In a case where the circumferential direction and the axial direction are used in the description of the sheet member100, the directions are the direction in a state where the sheet member100is wound around the cylinder main body52. Further, a direction along a short side of the rectangular sheet member100in a plan diagram is defined as a width direction, and a direction along a long side is defined as a length direction.

The cylinder main body52has a single recess54formed along the axial direction in a part of the circumferential direction, and has a substantially circular cross section, specifically, an outer shape of the cross section orthogonal to the axial direction. The recess54as an example of the concave portion has a depth along a radial direction of the cylinder main body52. Further, the cylinder main body52is made of a metal material such as stainless steel and aluminum. In the present exemplary embodiment, the depth direction of the recess54matches the radial direction. However, it is not necessary that the depth direction and the radial direction match. The depth direction may be inclined, for example, about 5° to 10° with respect to the radial direction.

The cylinder main body52is formed such that a length along the axial direction is longer than a width along the axial direction of the sheet member100, and the sheet member100is wound in a state where a central portion of the sheet member100in the width direction matches a central portion of the cylinder main body52in the axial direction. The sheet member100has a width larger than a maximum width of the recording medium P (seeFIG.4).

The “sheet shape” means a shape such as paper and a thin plate having a thickness that can be deformed along an outer circumference of the cylinder main body52. The length of the sheet member100in the circumferential direction (length direction) is configured to be substantially the same as the length of the cylinder main body52in the circumferential direction excluding the recess54.

As shown inFIG.6, the sheet member100has a metal layer150that is wound in contact with the outer circumferential surface of the cylinder main body52, and an outer layer102that is laminated and adhered to the outer circumferential surface of the metal layer150.

As the metal layer150of the present exemplary embodiment, a metal material such as stainless steel, aluminum, and copper is used. The thickness of the metal layer150in the present exemplary embodiment is, for example, 0.1 mm.

For the outer layer102of the present exemplary embodiment, a conductive resin material such as solid rubbers such as nitrile rubber, chloroprene rubber, ethylene propylene diene rubber, acrylic nitrile butadiene rubber, and silicon rubber, polyimide, polyamide imide, polyurethane, polyethylene, and mixtures thereof are used. The thickness of the outer layer102in the present exemplary embodiment is thicker than the thickness of the metal layer150, for example, 7.0 mm.

In the present exemplary embodiment, one end of the sheet member100is fixed to the cylinder main body52by a mounting screw71, and the other end is fixed to the cylinder main body52by a fixing screw70. Therefore, the sheet member100is easily attached to and detached from the cylinder main body52.

FIG.7shows a perspective diagram of the sheet member100in a state of being removed from the cylinder main body52. Further,FIG.8shows a plan diagram of the sheet member100according to the present exemplary embodiment as viewed from the metal layer150side.

Next,FIG.9shows an enlarged peripheral diagram of the transfer position where the transfer cylinder50and the opposing roll24are close to each other and the image on the transfer belt30is transferred to the recording medium P.

FIG.9shows how the transfer cylinder50rotates with the gripper36accommodated in the recess54. Then, it can be seen that the sliding member60is disposed close to the transfer cylinder50on the downstream side of the transfer position in the rotation direction.

A perspective diagram of the sliding member60is shown inFIG.10. Referring toFIG.10, the sliding member60is composed of a main body portion61, a fixing metal fitting62, and a plate-shaped portion63. The plate-shaped portion63is a member for imparting a transport load to the recording medium P by coming into contact with the transported recording medium P, and is fixed to the fixing metal fitting62by, for example, screwing. Then, the fixing metal fitting62is fixed to the main body portion61by screwing or the like, such that the plate-shaped portion63is fixed to the main body portion61via the fixing metal fitting62.

The plate-shaped portion63is a member that comes into direct contact with the transported recording medium P, and is made of, for example, a material such as rubber having a friction coefficient between the plate-shaped portion63and the recording medium P of 1.0 or more and 1.5 or less. The material configuring the plate-shaped portion63is not limited to rubber, and other materials such as a resin material and a metal material can also be used.

Next, the reason for imparting the transport load to the recording medium P being transported by the sliding member60as described above will be described.

First,FIG.11shows an example of a state of the recording medium P in a case where the sliding member60is not present. InFIG.11, the outer shapes of the sliding member60, the transfer cylinder50, and the like are shown schematically in a simplified manner. InFIG.11, it can be seen that the recording medium P grasped by the gripper36is lifted by the transfer cylinder50, floating is generated, and the recording medium P comes into contact with the transfer belt30before the image of the transfer belt30is transferred to the recording medium P at an original transfer position. In a case where such a state occurs, transfer deviation occurs in the image transferred on the recording medium P, and an image quality deteriorates. Specifically, as an example, image deterioration occurs in which lines in the image are blurred and thickened and a line width is widened.

Next,FIG.12shows an example of a state of the recording medium P in a case where the sliding member60is present. Referring toFIG.12, it can be seen that the recording medium P grasped by the gripper36and the sliding member60slide, such that the recording medium P is pulled to the downstream side in the transport direction and the floating of the recording medium P is suppressed. In particular, in the image forming apparatus10of the present exemplary embodiment, since the tip of the recording medium P is transported while being grasped by the gripper36, the effect of suppressing floating can be remarkably obtained by pulling the recording medium P to the downstream side in the transport direction.

The sliding member60in the present exemplary embodiment has a plate shape, and by adjusting a distance between the tip of the sliding member60and the opposing roll24and a distance between the tip of the sliding member60and a surface of the transfer cylinder50, the effect of suppressing the floating of the recording medium P changes.

Specifically, the effect of suppressing floating becomes stronger in a case where the distance between the tip of the sliding member60and the opposing roll24is shortened. However, in a case where the sliding member60is located too close to the opposing roll24, there is a high possibility that the sliding member60will come into contact with the transfer belt30. Further, the shorter the distance between the tip of the sliding member60and the surface of the transfer cylinder50, the larger the transport resistance imparted to the recording medium P, and the transport resistance can be applied to the thin recording medium P as well.

Therefore, as shown inFIG.13, an amount of image shift generated has been evaluated by changing a distance A between the tip of the sliding member60and a center of the opposing roll24and a distance B between the tip of the sliding member60and the surface of the transfer cylinder50.

Specifically, an image of thin lines of two dots has been formed in a direction orthogonal to the transport direction of the recording medium P, and the evaluation has been performed based on how wide the width of the thin lines is. In a case where the image shift does not occur, the width of the image of thin lines remains the same, but in a case where the image shift occurs, the width of the thin line widens. Therefore, it has been evaluated whether the width of the image of thin lines is acceptable or not.

Based on the evaluation result, good evaluation result has been obtained by disposing the tip of the sliding member60at a position where the distance A from the center of the opposing roll24is 50 mm or less and the distance B from the surface of the transfer cylinder50is 2 mm or less.

In a case where it is desired to surely impart transport resistance to the transported recording medium P, that is, in a case where it is desired to impart transport resistance regardless of the thickness of the recording medium P to be transported, the sliding member60may be disposed so as to be in contact with the surface of the transfer cylinder50. However, in such a disposition, the ink-accepting particles and the like adhering to the transfer cylinder50may adhere to the sliding member60and contaminate the transported recording medium P. Further, there is a possibility that the sliding member60and the transfer cylinder50are always in constant contact with each other and worn, such that the deterioration progresses quickly.

Therefore, considering the effects of contamination on the image transferred on the recording medium P, deterioration of the transfer cylinder50and the sliding member60due to wear, and influence of the transport resistance of the transported recording medium P, it is desirable to dispose the sliding member60in a non-contact manner with respect to the transfer cylinder50.

Further, a paper having a weak waist, that is, a thin paper has a small floating from the transfer cylinder50, and a paper having a strong waist, that is, a thick paper has a large floating from the transfer cylinder50. Specifically, the thickness of general paper is about 0.09 mm, the thickness of thick paper is about 0.15 mm, and the thickness of particularly thick paper is 0.2 mm or more. Therefore, in a case where the paper is thin and has a weak waist, the position of the sliding member60may be set so as not to come into contact with the transfer cylinder50or to come into contact with the transfer cylinder50weakly. Further, in a case of plain paper, the position of the sliding member60may be set so as to come into contact with the transfer cylinder50weakly than the thick paper. In a case of the thick paper, the position of the sliding member60may be set such that, in a case where there is no floating, the sliding member60does not come into contact with the transfer cylinder50, but in a case where there is floating, the transfer cylinder50comes into contact with the sliding member60thereby suppressing the floating. Further, in a case of special paper, the position of the sliding member60may be set such that the sliding member60can come into contact with the transfer cylinder50regardless of floating. The distance between the sliding member60and the surface of the transfer cylinder50is set in consideration of various conditions as described above.

In the above description, a configuration in which the transport load is imparted to the recording medium P transported by the transport unit14, by the plate-shaped sliding member60has been described, but the transport load may be imparted to the recording medium P by another configuration.

For example, as shown inFIG.14, the transport load may be imparted to the recording medium P by a rotary roll65, which is a rotating member that is disposed in close proximity without coming into contact with the surface of the transfer cylinder50and that rotates in contact with the transported recording medium P.

The rotary roll65may be a rotating member that rotates in contact with the surface of the transfer cylinder50.

At this time, the rotary roll65may be a driven roll configured to rotate by a frictional force with the surface of the transfer cylinder50or the recording medium P, or a drive roll that is driven by a driving force from the outside.

FIG.15shows a configuration in a case where the rotary roll65is a drive roll. The rotary roll65shown inFIG.15is driven by a driving force of a drive unit66. In a case where the rotary roll65is driven in this way, it is configured to rotate at a surface speed slower than a surface speed of the transfer cylinder50.

Even in a case where a transport load is imparted to the recording medium P by the rotary roll65, by adjusting the distance between the rotary roll65and the opposing roll24and the distance between the rotary roll65and the surface of the transfer cylinder50, the effect of suppressing the floating of the recording medium P changes.

Therefore, as shown inFIG.16, the amount of image shift generated has been evaluated by changing the distance A between the center of the rotary roll65and the center of the opposing roll24and the distance B between the surface of the rotary roll65and the surface of the transfer cylinder50.

Based on the evaluation result, good evaluation result has been obtained by disposing the center of the rotary roll65such that the distance from the center of the opposing roll24is 50 mm or less, and the distance between the surface of the rotary roll65and the surface of the transfer cylinder50is 2 mm or less.

Similar to the sliding member60described above, the member configuring the rotary roll65can be made of, for example, a material such as rubber having a friction coefficient with the recording medium P of 1.0 or more and 1.5 or less. The material configuring the rotary roll65is not limited to rubber, and other materials such as a resin material and a metal material can also be used.

In the actual apparatus configuration, it may not be possible to impart a sufficient transport load as described above to the recording medium P due to various restrictions. Therefore, not only the transport load may be imparted to the recording medium P, but also the configuration as described below may be adopted to suppress the floating of the recording medium P from the transfer cylinder50.

FIG.17shows an enlarged diagram of the leading side of the transfer cylinder50in the rotation direction. Referring toFIG.17, at the tip of the surface in the recess54of the transfer cylinder50on the side that becomes the head in the rotation direction, a tapered surface104, which is an inclined surface that is inclined as the distance from the rotation center to the surface increases toward the downstream side in the rotation direction, is provided. As described above, the transfer cylinder50is composed of the cylinder main body52in which the recess54is provided in a direction substantially orthogonal to the rotation direction and the sheet member100wound around the cylinder main body52, and thus the tapered surface104is provided at the tip of the sheet member100on the side that becomes the head in the rotation direction.

Since the sheet member100is provided with the tapered surface104as described above, the recording medium P is suppressed from floating from the transfer cylinder50.FIG.18shows an example of the state of the recording medium P in a case where a sheet member100A that is not provided with the tapered surface104is used.

Referring toFIG.18, it can be seen that the recording medium P grasped by the gripper36is pushed up to the tip of the sheet member100A to cause floating, and comes into contact with the transfer belt30before a normal transfer position.

On the other hand,FIG.19shows an example of a state of the recording medium P in a case where the sheet member100provided with the tapered surface104is used.

Referring toFIG.19, the recording medium P grasped by the gripper36is not pushed up to the tip of the sheet member100, the occurrence of floating is suppressed, and the occurrence of a situation in which the recording medium P comes into contact with the transfer belt30at an unintended position is prevented.

It is more desirable that the position of the gripper36, an orientation of a grasping surface on which the gripper36grasps the recording medium P, and an inclination angle of the tapered surface104provided on the sheet member100satisfy a specific condition.

Specifically, as shown inFIG.20, it may be configured such that the tapered surface104is on a rotation center side of the transfer cylinder50with respect to a surface including the grasping surface120on which the gripper36grasps the recording medium P in a state where the gripper36is accommodated in the recess54.

Further, as shown inFIG.21, it may be configured such that an angle θ2between a tapered surface104and a plane orthogonal to a tip position of the tapered surface104on the line in the rotation center direction of the transfer cylinder50from the tip position of the tapered surface104is smaller than an angle θ1between a grasping surface120on which a gripper36grasps a recording medium P and a plane orthogonal to a tip position of the gripper36on a line in a rotation center direction of a transfer cylinder50from the tip position of the gripper36. That is, since it is configured such that θ2<θ1, there is a high possibility that the recording medium P grasped by the gripper36is on the tapered surface104. As a result, the occurrence of a situation in which the recording medium P is pushed up by the transfer cylinder50is prevented, and the floating of the recording medium P from the transfer cylinder50is suppressed.

Further, for example, it is more preferable that it is configured such that the distance between the tip of the sheet member100on the side that becomes the head in the rotation direction and the tip of the region of the gripper36for grasping the recording medium P is 3 mm or more. However, in a case where the gripper36is disposed at a position far from the tip of the transfer cylinder50, a tip margin region where an image is not formed from the beginning of the recording medium P increases, such that the position where the gripper36is separated from the transfer cylinder50is limited.

Further, by providing the tapered surface104on the sheet member100, the effect of alleviating an impact when the opposing roll24comes into contact with the transfer cylinder50at the transfer position can be obtained. However, in a case where the inclination of the tapered surface104provided on the sheet member100is made gentle and the distance is lengthened, since the tip margin region where an image is not formed from the beginning of the recording medium P increases, the distance and inclination of the tapered surface104are limited.

Therefore, by combining a configuration in which a transport load is imparted to the recording medium P by the sliding member60or the like described above and a configuration in which the tapered surface104is provided at the tip of the sheet member100, the floating of the recording medium P from the transfer cylinder50is suppressed while preventing the increase of the tip margin region, such that the overall quality of the image formed on the recording medium P is improved.

Another Image Forming Apparatus

FIG.22shows a schematic diagram showing a configuration of another image forming apparatus10according to an exemplary embodiment of the present invention. The image forming apparatus10according to the present exemplary embodiment is not limited to the ink-jet type as described above, and may be, for example, an electrophotographic type as shown inFIG.22. That is, instead of the pressure-sensitive adhesive layer forming device26, the particle supply device18, and the discharge head20, a toner image forming unit80for forming a toner image (an example of an image) of each color may be provided.

The toner image forming unit80(80Y,80M,80C, and80K) of each color has a columnar photoreceptor82that rotates in one direction (arrow B direction) respectively, and a charger84, an exposure device86, and a developing device88are disposed around each photoreceptor82in order from the upstream side of the photoreceptor82in the rotation direction.

In the toner image forming unit80of each color, the charger84charges a surface of the photoreceptor82, and the exposure device86exposes the surface of the photoreceptor82charged by the charger84to form an electrostatic latent image on the surface of the photoreceptor82. Then, the developing device88develops the electrostatic latent image formed on the surface of the photoconductor82by the exposure device86to form a toner image.

On the inner circumferential surface side of the transfer belt30, a primary transfer roll78facing each photoreceptor82with the transfer belt30interposed therebetween is provided. The toner images formed by the toner image forming unit80of each color are sequentially primarily transferred to the transfer belt30at a primary transfer position T1 in which the primary transfer roll78is provided and superimposed, and the superimposed toner image is secondarily transferred to the recording medium P at a secondary transfer position T2.

Others

The present invention is not limited to the above exemplary embodiment, and the design can be appropriately changed without departing from the gist of the present invention.

For example, in the above exemplary embodiment, by imparting a transport load to the transported recording medium P by the imparting portion such as the sliding member60, the floating of the recording medium P from the transfer cylinder50is suppressed. However, the present invention is not limited to such a configuration. For example, it is also possible to use an air adsorption method in which the recording medium P is brought into close contact with the transfer cylinder50by negative pressure, or an electrostatic adsorption method in which the recording medium P is brought into close contact with the transfer cylinder50by electrostatic force by applying a voltage to the transfer cylinder50.

Further, the cylinder main body52may be formed in a substantially columnar shape instead of a substantially cylindrical shape. Further, in the present exemplary embodiment, a toner image is taken as an example of the image, and the toner image is formed by a dry electrophotographic method, but the present invention is not limited to this. For example, a toner image formed by a wet electrophotographic method may be used.

The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.