Patent Description:
<CIT> discloses a printer that forms an image on an image formation surface of a disc transported by a transport device. In this printer, a toner image given to a transfer belt is electrically transferred onto the image formation surface of the disc by bringing an electrode of a transfer device into contact with the image formation surface and supplying an electric charge. <CIT> discloses an image forming apparatus for forming an image on an optical disk or similar synthetic resin sheet. The apparatus exerts a preselected pressure for each of image transfer and image fixation to thereby insure high quality images. Further, the apparatus matches the moving speed of the surface of a synthetic resin sheet and the peripheral speed of an image carrier or that of a fixing member.

Some image forming apparatuses bring a transfer unit into contact with an image formation surface of a recording medium transported by a transport unit and thereby transfer an image formed with particles such as toner onto the recording medium. The transfer unit transfers the image formed with particles onto the recording medium by an electric field formed between the transfer unit and the recording medium.

In such an image forming apparatus, it is desirable to provide a support unit that supports a recording medium from a perspective of making misregistration of the recording medium less likely to occur due to a shock caused when the transfer unit makes contact with the recording medium. Meanwhile, in a case where the recording medium is supported by the support unit, if the support unit and the transfer unit are directly conductive with each other, particles such as toner may be undesirably attached from the transfer unit to the support unit by an electric field between the transfer unit and the support unit.

The following disclosure serves a better understanding of the present invention. Accordingly, it is an object of the present disclosure to provide a technique of making particles less likely to be attached to a support unit that supports a recording medium than in a case where the support unit and a transfer unit are directly conductive with each other.

An exemplary embodiment of the present disclosure is described in detail below with reference to the attached drawings. An image forming apparatus according to the present exemplary embodiment is an image forming apparatus employing digital printing. Although an electrophotographic system, an inkjet system, and the like are known as digital printing systems, the electrophotographic system is assumed in the present exemplary embodiment. In the electrophotographic system, a transfer unit and a medium are brought into contact with each other when an image is transferred onto the medium. Furthermore, in the present exemplary embodiment, any of media having various thicknesses and shapes such as metal, glass, and tile is assumed as an object on which an image is to be printed.

<FIG> illustrates a configuration of an image forming apparatus to which the present exemplary embodiment is applied. The image forming apparatus <NUM> includes a transfer unit <NUM>, a fixing unit <NUM>, a medium attaching detaching unit <NUM>, and a transport mechanism <NUM>. Furthermore, the image forming apparatus <NUM> includes a controller <NUM> having one or more processors, which are computing units, a memory serving as a working region in data processing, and a storage device that holds a program and data. Although the controller <NUM> is a single controller that controls operation of the whole image forming apparatus <NUM> in this example, the controller <NUM> may be individually provided in units such as the transfer unit <NUM>, the fixing unit <NUM>, and the transport mechanism <NUM>.

The transfer unit <NUM> is a unit that transfers an image formed with particles such as toner onto a recording medium <NUM> (hereinafter simply referred to as a medium <NUM>). The fixing unit <NUM> is a unit that fixes, on a surface of the medium <NUM>, an image transferred by the transfer unit <NUM> by heating the medium <NUM>. The medium attaching detaching unit <NUM> is a unit in which a user of the image forming apparatus <NUM> attaches the medium <NUM> to an attachment table (described later) provided in the transport mechanism <NUM>. The transport mechanism <NUM> is provided across the transfer unit <NUM>, the fixing unit <NUM>, and the medium attaching detaching unit <NUM>, and transports the medium <NUM> on which an image is to be printed to the units <NUM>, <NUM>, and <NUM> as indicated by the arrow in <FIG>.

<FIG> illustrates a configuration of the transfer unit <NUM>. The transfer unit <NUM> forms an image with charged particles and transfers the image onto the medium <NUM> by generating an electric field. The transfer unit <NUM> includes a developing device <NUM>, a first transfer roll <NUM>, and an intermediate transfer belt <NUM>. The intermediate transfer belt <NUM> is tensioned between the developing device <NUM> and a position where an image is transferred onto the medium <NUM> by rollers <NUM> and <NUM> and a backup roll <NUM>. Furthermore, the transfer unit <NUM> includes a cleaning device <NUM> for removing particles attached to the intermediate transfer belt <NUM>. Furthermore, the transfer unit <NUM> includes a power source <NUM> that applies a predetermined voltage to the backup roll <NUM>.

The developing device <NUM> is a unit that forms, on a photoreceptor, an electrostatic latent image of an image to be transferred and develops the image by attaching charged particles to the electrostatic latent image on the photoreceptor. As the developing device <NUM>, an existing device used in an electrophotographic image forming apparatus can be used. <FIG> illustrates an example of a configuration employed in a case where color image formation processing is performed by using four colors, that is, three colors: yellow, magenta, and cyan, and an additional one color: black. The developing device <NUM> is provided for each of these colors, and the developing devices <NUM> for yellow, magenta, cyan, and black are given alphabets (color signs) Y, M, C, and K indicative of the colors in <FIG>. In the following description, the suffixes are omitted in a case where the colors of the developing devices <NUM> need not be distinguished although the suffixes Y, M, C, and K are given to the reference signs in a case where the colors are distinguished.

The first transfer roll <NUM> is a unit used to transfer (first transfer) an image formed by the developing device <NUM> onto the intermediate transfer belt <NUM>. The first transfer roll <NUM> is disposed so as to face the photoreceptor of the developing device <NUM>, and the intermediate transfer belt <NUM> is located between the developing device <NUM> and the first transfer roll <NUM>. The first transfer roll <NUM> is provided corresponding to each of the developing devices 110Y, <NUM>, 110C, and <NUM>. In <FIG>, the first transfer rolls <NUM> corresponding to the developing devices 110Y, <NUM>, 110C, and <NUM> of the respective colors are given alphabets (color signs) Y, M, C, and K indicative of the colors. In the following description, the suffixes are omitted in a case where the colors of the first transfer rolls <NUM> need not be distinguished although the suffixes Y, M, C, and K are given to the reference signs in a case where the colors are distinguished.

The intermediate transfer belt <NUM>, the rollers <NUM> and <NUM>, and the backup roll <NUM> are units used to transfer an image formed by the developing device <NUM> onto the medium <NUM>. As illustrated in <FIG>, the intermediate transfer belt <NUM> rotates in a direction indicated by the arrows in <FIG> (a counterclockwise direction in the example illustrated in <FIG>) while being suspended around the rollers <NUM> and <NUM> and the backup roll <NUM> in a tensioned state. For example, one or both of the rollers <NUM> and <NUM> is(are) a roller(s) that is(are) driven to rotate, and the intermediate transfer belt <NUM> is pulled by rotation of this(these) roller(s). In this way, the intermediate transfer belt <NUM> rotates.

An outer surface of the intermediate transfer belt <NUM> in the example of the configuration in <FIG> is a surface (hereinafter referred to as a "transfer surface") on which an image is held. An image is transferred from the photoreceptor of the developing device <NUM> onto the transfer surface of the intermediate transfer belt <NUM> when the intermediate transfer belt <NUM> passes between the developing device <NUM> and the first transfer roll <NUM>. In the example of the configuration illustrated in <FIG>, images of the respective colors: yellow (Y), magenta (M), cyan (C), and black (K) are superimposed on the transfer surface by the developing devices 110Y, <NUM>, 110C, and <NUM> and the first transfer rolls 120Y, <NUM>, 120C, and <NUM>, and thus a multi-color image is formed.

The backup roll <NUM> transfers (second transfer) the image onto the medium <NUM> by bringing the transfer surface of the intermediate transfer belt <NUM> into contact with the medium <NUM>. A predetermined voltage is applied to the backup roll <NUM> by the power source <NUM> when the image is transferred. This generates an electric field (hereinafter referred to as a "transfer electric field") in a range including the backup roll <NUM> and the medium <NUM>, thereby transferring the image formed with charged particles from the intermediate transfer belt <NUM> onto the medium <NUM>. As described above, to transfer an image from the intermediate transfer belt <NUM> onto the medium <NUM>, an electric current need to flow from the backup roll <NUM> to the medium <NUM> through the intermediate transfer belt <NUM>. In a case where the medium <NUM> is a conductor such as a metal, an electric current flows through the medium <NUM> itself, and therefore an image is transferred onto a surface of the medium <NUM> by generating a transfer electric field. On the other hand, in a case where the medium <NUM> is not a conductor, no electric current flows through the medium <NUM>, and therefore an image cannot be transferred in this state. In view of this, in a case where the medium <NUM> is not a conductor, an electric current is passed through the medium <NUM> by taking a measure such as forming a layer made of an electrically conductive material (hereinafter referred to as an "electrically conductive layer") in advance in at least a region on the surface of the medium <NUM> where an image is to be formed.

A procedure of transfer of an image by the intermediate transfer belt <NUM> is described. When the intermediate transfer belt <NUM> rotates, images of the respective colors: yellow (Y), magenta (M), cyan (C), and black (K) are sequentially superimposed on the transfer surface (outer surface in <FIG>) of the intermediate transfer belt <NUM> by the developing devices 110Y, <NUM>, 110C, and <NUM> and the first transfer rolls 120Y, <NUM>, 120C, and <NUM>, and thus a multi-color image is formed. When the intermediate transfer belt <NUM> further rotates, the image formed on the transfer surface of the intermediate transfer belt <NUM> reaches a position (hereinafter referred to as a "transfer position") where the intermediate transfer belt <NUM> makes contact with the medium <NUM>. As described above, a voltage is applied to the backup roll <NUM>. This generates a transfer electric field, thereby transferring the image from the intermediate transfer belt <NUM> onto the medium <NUM>.

The cleaning device <NUM> is a unit that removes particles attached to the transfer surface of the intermediate transfer belt <NUM>. The cleaning device <NUM> is provided at a position on a downstream side relative to the transfer position and an upstream side relative to the developing device 110Y and the first transfer roll 120Y in a direction in which the intermediate transfer belt <NUM> rotates. With this configuration, particles remaining on the transfer surface of the intermediate transfer belt <NUM> are removed by the cleaning device <NUM> after the image is transferred from the intermediate transfer belt <NUM> onto the medium <NUM>. In a next operation cycle, an image is newly transferred (first transfer) onto the transfer surface from which particles have been removed. Configuration of Transport Mechanism <NUM> and Attachment Structure for Attachment of Medium <NUM>.

An attachment structure for attachment of the medium <NUM> is described. In the present exemplary embodiment, it is assumed that the medium <NUM> can have various thicknesses and shapes. In a case where the medium <NUM> directly placed on a transport path constituted by a belt and a roller is transported, it is difficult to bring the intermediate transfer belt <NUM> into contact with the medium <NUM> in a predetermined relationship since a height of the medium <NUM> relative to the transport path varies at the transfer position of the transfer unit <NUM> in a case where a thickness and a shape of the medium <NUM> vary. Specifically, such a situation can occur in which the medium <NUM> does not make contact with the intermediate transfer belt <NUM> in a case where the height of the medium <NUM> is low, and a strong shock is caused when the medium <NUM> makes contact with the intermediate transfer belt <NUM> in a case where the height of the medium <NUM> is high. In view of this, the transport mechanism <NUM> according to the present exemplary embodiment has the attachment table <NUM> having a height adjuster and transports the medium <NUM> placed on the attachment table <NUM> together with the attachment table <NUM>.

The transport mechanism <NUM> includes the transport rail <NUM> that specifies a transport path for the medium <NUM> and the attachment table <NUM> that moves on the transport rail <NUM> (see <FIG>). The attachment table <NUM> includes a leg part <NUM> attached to the transport rail <NUM> and a table part <NUM> on which the medium <NUM> is to be placed. Furthermore, a jig <NUM> that holds the medium <NUM> on the table part <NUM> is attached to the table part <NUM>.

In the example of the configuration illustrated in <FIG>, the transport rail <NUM> is disposed so as to extend from the medium attaching detaching unit <NUM> to the transfer unit <NUM> while passing the fixing unit <NUM>. An end portion of the transport rail <NUM> on a medium attaching detaching unit <NUM> side is the transport start position and the transport end position. The attachment table <NUM> is transported leftward in <FIG> from the transport start position of the medium attaching detaching unit <NUM>, and an image is transferred onto the medium <NUM> in the transfer unit <NUM>. Then, the attachment table <NUM> is transported rightward in <FIG>, and reaches the transport end position of the medium attaching detaching unit <NUM> after the image is fixed on the medium <NUM> in the fixing unit <NUM>.

The leg part <NUM> is attached to the transport rail <NUM> and moves on the transport rail <NUM>. A mechanism for moving the leg part <NUM> on the transport rail <NUM> is not limited in particular. For example, the leg part <NUM> may be provided with a driving device so as to be movable on its own or the transport rail <NUM> may be provided with a unit that pulls the leg part <NUM>. Furthermore, the leg part <NUM> has a height controller that controls a height of the table part <NUM>. A configuration of the height controller is not limited in particular. For example, the table part <NUM> may be moved up and down by rack and pinion and a drive motor. Alternatively, the height of the table part <NUM> may be controlled by manually operating a gear that is linked with the height of the table part <NUM>. Furthermore, various methods can be used as an operation method for controlling the height. For example, an input interface for input to a controller of the drive motor may be prepared, and an operator of the image forming apparatus <NUM> may manually input and set height data by using the input interface. Alternatively, the height of the medium <NUM> attached to the attachment table <NUM> may be automatically detected by using a sensor, and the drive motor may be controlled so that the medium <NUM> is located at an appropriate height.

The table part <NUM> is a table that is attached to the leg part <NUM> and on which the medium <NUM> is placed with the jig <NUM> interposed therebetween. The table part <NUM> is provided with a fastener (not illustrated) for positioning the jig <NUM>. Any jigs <NUM> compatible with this fastener can be positioned and attached to the table part <NUM> irrespective of shapes thereof.

Furthermore, the table part <NUM> is attached so as to float up and sink down with respect to the leg part <NUM> in accordance with a pressure applied from an upper side. The configuration in which the table part <NUM> floats up and sinks down is, for example, realized by interposing an elastic body at a portion where the table part <NUM> and the leg part <NUM> are joined. By employing such a configuration, a shock caused when the medium <NUM> held by the jig <NUM> attached to the table part <NUM> makes contact with the intermediate transfer belt <NUM> of the transfer unit <NUM> is lessened.

The table part <NUM> according to the present exemplary embodiment is made of an electrically conductive material. Furthermore, the table part <NUM> is in contact with a grounding member (not illustrated) and is connected to ground with the grounding member interposed therebetween.

The jig <NUM> is an example of a support unit and is a device that holds the medium <NUM> and is attached to the table part <NUM>. A portion of the jig <NUM> attached to the table part <NUM> has a shape and a structure compatible with the fastener of the table part <NUM>. Furthermore, the jig <NUM> has a shape for holding the medium <NUM>. Therefore, media <NUM> having various shapes and sizes can be placed on the attachment table <NUM> by preparing jigs <NUM> compatible with the shapes and sizes of the media <NUM>.

The jig <NUM> according to the present exemplary embodiment is made of an electrically conductive material. Furthermore, the portion of the jig <NUM> attached to the table part <NUM> is conductive with the table part <NUM>. Furthermore, the jig <NUM> supports the medium <NUM> so as to be conductive with a surface (an image formation surface, which will be described later) of the medium <NUM> including a region where an image is to be formed. In this way, the image formation surface of the medium <NUM> supported by the jig <NUM> is connected to ground with the jig <NUM> and the table part <NUM> interposed therebetween.

Note that a relationship between the jig <NUM> and the medium <NUM> will be described in detail later.

The image forming apparatus <NUM> according to the present exemplary embodiment has the transport mechanism <NUM> configured as above and therefore can print an image on any of the media <NUM> having various shapes and sizes. However, before start of image transfer operation, the height of the table part <NUM> is controlled in order to prevent a strong shock from being caused by contact of the medium <NUM> with the intermediate transfer belt <NUM> of the transfer unit <NUM> or prevent failure to bring the medium <NUM> into contact with the intermediate transfer belt <NUM> when an image is transferred onto the medium <NUM>.

<FIG> illustrate operation of the transport mechanism <NUM> before start of image formation by the transfer unit <NUM>. <FIG> illustrates how the height is controlled, <FIG> illustrates a state where the attachment table <NUM> has retreated to a preparation position after the height control, and <FIG> illustrates a state where the transfer unit <NUM> starts transfer of an image.

In a case where an image is formed on the medium <NUM>, first, the medium <NUM> held by the jig <NUM> is placed on the attachment table <NUM> at the transport start position of the medium attaching detaching unit <NUM>. Then, the medium <NUM> is lowered to a height at which the medium <NUM> does not make contact with the intermediate transfer belt <NUM> of the transfer unit <NUM> by the height controller of the attachment table <NUM>, and then the attachment table <NUM> on which the medium <NUM> is placed is moved to a position below the transfer position of the transfer unit <NUM>.

Next, the height of the attachment table <NUM> is controlled so that the medium <NUM> makes contact with the intermediate transfer belt <NUM> with a strength appropriate for transfer of the image at the transfer position (arrow a in <FIG>). When the height is controlled, information on an appropriate height (hereinafter referred to as a "transfer execution height") thus obtained is held, for example, in the memory of the controller <NUM> (see <FIG>). Then, the attachment table <NUM> is lowered to a height where the medium <NUM> does not make contact with the intermediate transfer belt <NUM> and moves to the preparation position for transfer operation (arrow b in <FIG>).

When the attachment table <NUM> moves to the preparation position, the height of the attachment table <NUM> is adjusted to the transfer execution height on the basis of the information obtained in the height control. Then, the attachment table <NUM> moves to the transfer position (arrow c in <FIG>), and transfer of the image starts when the medium <NUM> makes contact with the intermediate transfer belt <NUM> at the transfer position (<FIG>).

After the image is transferred onto the medium <NUM> in the transfer unit <NUM>, the image is fixed in the fixing unit <NUM>. In the present exemplary embodiment, an image is formed on any of the media <NUM> having various thicknesses and shapes, and therefore the fixing processing is performed by a non-contact-type device. The fixing unit <NUM> melts particles forming the image transferred onto the medium <NUM> by heating the particles and thereby fixes the particles on the surface of the medium <NUM>.

<FIG> illustrate a configuration and operation of the fixing unit <NUM>. <FIG> illustrates a state where openings of the fixing unit <NUM> are closed, and <FIG> illustrates a state where the openings of the fixing unit <NUM> are opened. The fixing unit <NUM> includes a carry-in opening <NUM>, which is an opening through which the medium <NUM> is carried into the fixing unit <NUM>, and a carry-out opening <NUM>, which is an opening through which the medium <NUM> is carried out of the fixing unit <NUM>. Furthermore, the carry-in opening <NUM> and the carry-out opening <NUM> of the fixing unit <NUM> according to the present exemplary embodiment are provided with an opening and closing member and are configured to be opened when the medium <NUM> is carried into or out of the fixing unit <NUM> and be closed when the fixing processing is performed.

The fixing unit <NUM> includes a heat source <NUM> for thermal fixation. The heat source <NUM> can be, for example, any of various existing heat sources such as a halogen lamp, a ceramic heater, and an infrared lamp. Instead of the heat source <NUM>, a device that heats particles forming the image by emitting infrared laser may be used. The fixing unit <NUM> according to the present exemplary embodiment is provided with a member that can cover the heat source <NUM>, and is configured so that the heat source <NUM> is exposed when the fixing processing is performed.

In the example illustrated in <FIG>, roll-up shutters <NUM> and <NUM> are provided as the opening and closing members of the carry-in opening <NUM> and the carry-out opening <NUM>. The shutters <NUM> and <NUM> are closed (see <FIG>) except when the medium <NUM> is carried into and out of the fixing unit <NUM> and thereby prevent a decrease in internal temperature. The shutter <NUM> of the carry-in opening <NUM> opens when the medium <NUM> is carried into the fixing unit <NUM>, and the shutter <NUM> of the carry-out opening <NUM> opens when the medium <NUM> is carried out of the fixing unit <NUM> (see <FIG>).

In the example illustrated in <FIG>, a roll-up shutter <NUM> is provided as the covering member that covers the heat source <NUM>. The shutter <NUM> closes in a case where the shutter <NUM> of the carry-in opening <NUM> and/or the shutter <NUM> of the carry-out opening <NUM> open(s) (see <FIG>). This may keep a decrease in temperature of the heat source <NUM> small even in a case where the carry-in opening <NUM> and/or the carry-out opening <NUM> open(s) and the internal temperature decreases.

In the example illustrated in <FIG>, a state where both of the shutter <NUM> of the carry-in opening <NUM> and the shutter <NUM> of the carry-out opening <NUM> are opened is illustrated for convenience of description. In actual operation, the shutter <NUM> of the carry-out opening <NUM> remains closed when the medium <NUM> is carried into the fixing unit <NUM>, and the shutter <NUM> of the carry-in opening <NUM> remains closed when the medium <NUM> is carried out of the fixing unit <NUM>. This keeps a decrease in internal temperature small.

The shutters <NUM>, <NUM>, and <NUM> illustrated in <FIG> are an example of the opening and closing members of the carry-in opening <NUM> and the carry-out opening <NUM> and the covering member of the heat source <NUM>. The opening and closing members and covering member are not limited to the above configuration, as long as the opening and closing members and covering member keep a decrease in internal temperature of the fixing unit <NUM> and temperature of the heat source <NUM> small. For example, an opening and closing door may be provided instead of the shutters <NUM>, <NUM>, and <NUM> illustrated in <FIG>. As the opening and closing member of the carry-out opening <NUM> through which the medium <NUM> passes after the fixing processing is finished, a curtain made of a heat insulating material or air curtain may be used to prevent leakage of internal air.

See <FIG> again. As described above, the medium attaching detaching unit <NUM> is a unit that is located at the transport start position and the transport end position, which are an end portion of the transport rail <NUM>. In the medium attaching detaching unit <NUM>, the jig <NUM> is attached and detached to and from the attachment table <NUM> or the medium <NUM> is attached and detached to and from the jig <NUM> attached to the attachment table <NUM>.

Furthermore, the medium attaching detaching unit <NUM> according to the present exemplary embodiment includes a cleaning device <NUM> for removing particles attached to an upper surface <NUM> (see <FIG>, which will be described later) of the jig <NUM>. The cleaning device <NUM> has, for example, a brush, a web, or the like that makes contact with the upper surface <NUM> of the jig <NUM>.

After an image is fixed on the medium <NUM> in the fixing unit <NUM>, the attachment table <NUM> on which the jig <NUM> holding the medium <NUM> is placed moves to the transport end position of the medium attaching detaching unit <NUM>. At the transport end position of the medium attaching detaching unit <NUM>, the medium <NUM> is removed from the jig <NUM> attached to the attachment table <NUM>. Then, the particles attached to the upper surface <NUM> of the jig <NUM> are removed by the cleaning device <NUM>.

Then, a new medium <NUM> is placed on the jig <NUM>, and image formation operation on this new medium <NUM> is performed.

As described above, in the image forming apparatus <NUM> according to the present exemplary embodiment, an image formed with particles is transferred from the transfer surface of the intermediate transfer belt <NUM> onto the medium <NUM> by bringing the transfer surface of the intermediate transfer belt <NUM> into contact with the medium <NUM> held by the jig <NUM>. During this process, the transfer surface of the intermediate transfer belt <NUM> and the upper surface <NUM> of the jig <NUM> sometimes make contact with each other, and particles are sometimes attached from the intermediate transfer belt <NUM> to the upper surface <NUM> of the jig <NUM>. In a case where particles are attached to the upper surface <NUM> of the jig <NUM>, the particles are sometimes attached to a new medium <NUM> and smear the new medium <NUM> when the new medium <NUM> is placed on the jig <NUM> after image formation operation on the medium <NUM> is finished.

In the present exemplary embodiment, the particles attached to the jig <NUM> are removed by the cleaning device <NUM>, and therefore it is less likely that the particles are attached to and smear the medium <NUM> placed on the jig <NUM>.

As described above, in the transfer unit <NUM> according to the present exemplary embodiment, when the attachment table <NUM> on which the medium <NUM> is placed moves to the transfer position, the backup roll <NUM> and the image formation surface of the medium <NUM> make contact with each other with the intermediate transfer belt <NUM> interposed therebetween. This forms a transfer electric field between the backup roll <NUM> and the image formation surface of the medium <NUM>, thereby transferring an image formed with particles from the transfer surface of the intermediate transfer belt <NUM> onto the image formation surface of the medium <NUM>.

As described above, the jig <NUM> holding the medium <NUM> has electric conductivity and is connected to ground with the table part <NUM> interposed therebetween. Accordingly, if the intermediate transfer belt <NUM> makes contact with the jig <NUM> and the backup roll <NUM> and the jig <NUM> become directly conductive with each other with the intermediate transfer belt <NUM> interposed therebetween when the attachment table <NUM> moves to the transfer position, particles are sometimes attached from the transfer surface of the intermediate transfer belt <NUM>, for example, onto the upper surface <NUM> of the jig <NUM> due to an electric field between the backup roll <NUM> and the jig <NUM>.

In the description of the present exemplary embodiment, a state where the jig <NUM> and members that constitute the transfer unit <NUM> such as the intermediate transfer belt <NUM> and the backup roll <NUM> are directly conductive with each other means a state where the jig <NUM> is conductive with members that constitute the transfer unit <NUM> by directly making contact with or facing the members without the medium <NUM> interposed therebetween. Specifically, in a case where the backup roll <NUM> and the image formation surface of the medium <NUM> make contact with each other with the intermediate transfer belt <NUM> interposed therebetween, the jig <NUM> is not directly conductive with the intermediate transfer belt <NUM> and the backup roll <NUM> although the jig <NUM> is conductive with the intermediate transfer belt <NUM> and the backup roll <NUM> with the medium <NUM> interposed therebetween.

In the present exemplary embodiment, the jig <NUM> supports the medium <NUM> so as not to make contact with the intermediate transfer belt <NUM>, and thereby the jig <NUM> is prevented from becoming directly conductive with the intermediate transfer belt <NUM> and the backup roll <NUM>. In this way, particles are less likely to be attached from the intermediate transfer belt <NUM> onto the jig <NUM>.

A shape of the jig <NUM> and a relationship between the jig <NUM> and the intermediate transfer belt <NUM> and the backup roll <NUM> according to the present exemplary embodiment are described in detail below. In the following description, the transport direction means a transport direction (a direction indicated by arrow c in <FIG>) in which the attachment table <NUM>, the medium <NUM> attached to the attachment table <NUM>, or the like is transported from the preparation position to the transport end position by passing through the transfer position.

<FIG> is a perspective view illustrating the jig <NUM> and the medium <NUM> held by the jig <NUM> to which the first exemplary embodiment is applied.

<FIG> illustrate a relationship between (i) the jig <NUM> and the medium <NUM> to which the first exemplary embodiment is applied and (ii) the intermediate transfer belt <NUM> and the backup roll <NUM>, and <FIG> illustrates an example using the jig <NUM> illustrated in <FIG>, and <FIG> illustrates an example using a modification of the jig <NUM>. Note that <FIG> are cross-sectional views of the jig <NUM> and the medium <NUM> taken along the transport direction at a central part in a width direction thereof.

The medium <NUM> according to the present exemplary embodiment has a front surface <NUM> and a rear surface <NUM> that are rectangular, a pair of first side surfaces <NUM> that connect the front surface <NUM> and the rear surface <NUM> and face each other, and a pair of second side surfaces <NUM> that connect the front surface <NUM> and the rear surface <NUM> and face each other, and has a flattened rectangular parallelepiped shape as a whole. In this example, the front surface <NUM> of the medium <NUM> is the image formation surface including the region where an image is to be formed. The whole medium <NUM> including the front surface <NUM>, which is the image formation surface, according to the present exemplary embodiment is made of a conductor.

As described above, the jig <NUM> holds the medium <NUM> and is attached to the table part <NUM>.

The jig <NUM> according to the present exemplary embodiment has the rectangular upper surface <NUM> that faces the intermediate transfer belt <NUM> when transported to the transfer position and a rectangular lower surface <NUM> opposite to the upper surface <NUM>, and has a rectangular parallelepiped shape as a whole. The jig <NUM> is attached to the table part <NUM> so that the lower surface <NUM> faces the table part <NUM>, and the jig <NUM> is conductive with the table part <NUM> through the lower surface <NUM>.

Furthermore, the jig <NUM> has, in a central part thereof in the transport direction of the transport mechanism <NUM>, a recessed part <NUM> that is recessed from the upper surface <NUM> toward the lower surface <NUM>. The medium <NUM> is inserted into a space formed inside the recessed part <NUM> of the jig <NUM>, and thus the medium <NUM> is supported in the recessed part <NUM>. In this example, the medium <NUM> is inserted into the recessed part <NUM> of the jig <NUM> so that the pair of first side surfaces <NUM> extend along the transport direction in which the medium <NUM> is transported by the transport mechanism <NUM> and the pair of second side surfaces <NUM> extend along a width direction of the medium <NUM> orthogonal to the transport direction.

The recessed part <NUM> of the jig <NUM> has an inner peripheral surface that matches the shape of the medium <NUM>. Specifically, the recessed part <NUM> has a pair of first inner peripheral surfaces <NUM> that extend along the transport direction of the transport mechanism <NUM> and face each other with the space in the recessed part <NUM> interposed therebetween and a pair of second inner peripheral surfaces <NUM> that extend along the width direction orthogonal to the transport direction of the transport mechanism <NUM> and face each other with the space in the recessed part <NUM> interposed therebetween. Furthermore, the recessed part <NUM> has a bottom surface <NUM> extending from lower ends of the first inner peripheral surfaces <NUM> and the second inner peripheral surfaces <NUM> along the transport direction and the width direction.

In the recessed part <NUM>, a length of each of the first inner peripheral surfaces <NUM> along the transport direction, in other words, an interval between the second inner peripheral surfaces <NUM> that face each other is equal to a length of the medium <NUM> in the transport direction. Furthermore, in the recessed part <NUM>, a length of each of the second inner peripheral surfaces <NUM> along the width direction, in other words, an interval between the first inner peripheral surfaces <NUM> that face each other is equal to a length of the medium <NUM> along the width direction.

Furthermore, a height of the first inner peripheral surfaces <NUM> and the second inner peripheral surfaces <NUM> of the recessed part <NUM> of the jig <NUM> according to the present exemplary embodiment, in other words, a height of the recessed part <NUM> from the bottom surface <NUM> to the upper surface <NUM> is lower than a height of the medium <NUM>, more specifically, a height of the first side surfaces <NUM> and the second side surfaces <NUM> of the medium <NUM>.

The medium <NUM> is inserted into the recessed part <NUM>, and thereby the jig <NUM> supports the first side surfaces <NUM> and the second side surfaces <NUM>, which are side surfaces of the medium <NUM>. Specifically, when the medium <NUM> is inserted into the recessed part <NUM> of the jig <NUM>, the first inner peripheral surfaces <NUM> and the second inner peripheral surfaces <NUM> of the recessed part <NUM> of the jig <NUM> and the first side surfaces <NUM> and the second side surfaces <NUM> of the medium <NUM> make contact with each other. Furthermore, the bottom surface <NUM> of the recessed part <NUM> of the jig <NUM> and the rear surface <NUM> of the medium <NUM> make contact with each other.

In the present exemplary embodiment, when the medium <NUM> is inserted into the recessed part <NUM>, the jig <NUM> and the medium <NUM> make contact with each other, and thereby the jig <NUM> and the medium <NUM> become conductive with each other. As a result, the front surface <NUM> of the medium <NUM>, which is the image formation surface, is connected to ground with the jig <NUM> and the table part <NUM> interposed therebetween.

Furthermore, in the present exemplary embodiment, the height of the recessed part <NUM> of the jig <NUM> is lower than the height of the medium <NUM>, as described above. Accordingly, in a state where the medium <NUM> is in the recessed part <NUM> of the jig <NUM> attached to the table part <NUM>, the height of the jig <NUM> is lower than a height of the image formation surface of the medium <NUM>. More specifically, a height from the table part <NUM> to the upper surface <NUM> of the jig <NUM> is lower than a height from the table part <NUM> to the front surface <NUM> of the medium <NUM>, which is the image formation surface. Furthermore, in a case where the attachment table <NUM> moves to the transfer position, a distance from the transfer surface of the intermediate transfer belt <NUM> to the upper surface <NUM> of the jig <NUM> is longer than a distance from the transfer surface of the intermediate transfer belt <NUM> to the front surface <NUM> of the medium <NUM>.

Since the jig <NUM> and the medium <NUM> have such a relationship, the intermediate transfer belt <NUM> makes contact with the front surface <NUM> of the medium <NUM> without making contact with the upper surface <NUM> of the jig <NUM> in a case where the attachment table <NUM> moves to the transfer position in a state where the height of the attachment table <NUM> has been controlled so that the front surface <NUM> of the medium <NUM> makes contact with the intermediate transfer belt <NUM> with a strength appropriate for transfer of an image. Specifically, the intermediate transfer belt <NUM> does not make contact with a front end side of the upper surface <NUM> of the jig <NUM> in the transport direction before the intermediate transfer belt <NUM> makes contact with the front surface <NUM> of the medium <NUM>.

Then, an image is transferred from the transfer surface of the intermediate transfer belt <NUM> onto the front surface of the medium <NUM> without bringing the intermediate transfer belt <NUM> into contact with regions of the upper surface <NUM> of the jig <NUM> on both end sides in the width direction of the medium <NUM> while the intermediate transfer belt <NUM> is in contact with the front surface <NUM> of the medium <NUM>.

Furthermore, after the image is transferred from the transfer surface of the intermediate transfer belt <NUM> onto the front surface <NUM> of the medium <NUM>, the attachment table <NUM> is moved from the transfer position to the transport end position without bringing the intermediate transfer belt <NUM> into contact with a rear end side of the upper surface <NUM> of the jig <NUM> in the transport direction.

This keeps the upper surface <NUM> of the jig <NUM> from becoming directly conductive with the intermediate transfer belt <NUM> and the backup roll <NUM>, thereby keeping particles from being attached from the transfer surface of the intermediate transfer belt <NUM> to the upper surface <NUM> of the jig <NUM> by a transfer electric field.

Although the upper surface <NUM> of the jig <NUM> illustrated in <FIG> is a flat surface extending along the transport direction of the transport mechanism <NUM> and the width direction of the medium <NUM>, the upper surface <NUM> need not be a flat surface.

For example, the upper surface <NUM> of the jig <NUM> may have, on a front end side in the transport direction relative to the recessed part <NUM>, an inclined surface 431a whose height decreases toward the front side in the transport direction, as illustrated in <FIG>. In a case where the upper surface <NUM> of the jig <NUM> has the inclined surface 431a on the front side in the transport direction, a distance from the transfer surface of the intermediate transfer belt <NUM> to the upper surface <NUM> of the jig <NUM> increases toward the front side in the transport direction. With this configuration, when the attachment table <NUM> enters the transfer position, the transfer surface of the intermediate transfer belt <NUM> and the front end of the upper surface <NUM> of the jig <NUM> are less likely to make contact with each other. This further keeps particles from being attached from the transfer surface of the intermediate transfer belt <NUM> to the upper surface <NUM> of the jig <NUM> by a transfer electric field.

Furthermore, the upper surface <NUM> of the jig <NUM> may have, on a rear end side in the transport direction relative to the recessed part <NUM>, an inclined surface 431b whose height decreases toward the rear side in the transport direction. In a case where the upper surface <NUM> of the jig <NUM> has the inclined surface 431b on the rear side in the transport direction, a distance from the transfer surface of the intermediate transfer belt <NUM> to the upper surface <NUM> of the jig <NUM> increases toward the rear side in the transport direction. With this configuration, when the attachment table <NUM> moves from the transfer position toward the transport end position after an image is transferred from the transfer surface of the intermediate transfer belt <NUM> onto the front surface <NUM> of the medium <NUM>, the transfer surface of the intermediate transfer belt <NUM> and the rear end of the upper surface <NUM> of the jig <NUM> are less likely to make contact with each other. This further keeps particles from being attached from the transfer surface of the intermediate transfer belt <NUM> to the upper surface <NUM> of the jig <NUM> by a transfer electric field.

Next, the second exemplary embodiment of the present disclosure is described. Note that constituent elements similar to those in the first exemplary embodiment are given identical reference signs, and detailed description thereof is omitted.

In the first exemplary embodiment, the jig <NUM> is kept from making contact with the intermediate transfer belt <NUM>, and thereby the jig <NUM> is kept from becoming directly conductive with the intermediate transfer belt <NUM> and the backup roll <NUM>. The second exemplary embodiment is different from the first exemplary embodiment in that the jig <NUM> is kept from becoming directly conductive with the intermediate transfer belt <NUM> and the backup roll <NUM> by providing an insulating layer made of an insulator on a portion of the jig <NUM> that makes contact with the intermediate transfer belt <NUM>.

<FIG> illustrate a jig <NUM> and a medium <NUM> to which the second exemplary embodiment is applied, and <FIG> is a view of the jig <NUM> and the medium <NUM> viewed from an upper side (intermediate transfer belt <NUM> side), and <FIG> is a cross-sectional view of the jig <NUM> and the medium <NUM> taken along a transport direction in a central part in a width direction thereof. <FIG> illustrates an intermediate transfer belt <NUM> and a backup roll <NUM> of a transfer unit <NUM> (see <FIG>) in addition to the jig <NUM> and the medium <NUM>.

The jig <NUM> according to the present exemplary embodiment has a rectangular parallelepiped shape having a rectangular upper surface <NUM> and a rectangular lower surface <NUM> and has a recessed part <NUM> in a central part in the transport direction of a transport mechanism <NUM> (see, for example, <FIG>), as in the first exemplary embodiment. Furthermore, the recessed part <NUM> of the jig <NUM> has a pair of first inner peripheral surfaces <NUM> and a pair of second inner peripheral surfaces <NUM> that match a shape of the medium <NUM>, and a bottom surface <NUM>.

A height of the first inner peripheral surfaces <NUM> and the second inner peripheral surfaces <NUM> of the recessed part <NUM> of the jig <NUM> according to the present exemplary embodiment, in other words, a height of the recessed part <NUM> from the bottom surface <NUM> to the upper surface <NUM> is equal to a height of the medium <NUM>, more specifically, a height of first side surfaces <NUM> and second side surfaces <NUM> of the medium <NUM>, unlike the first exemplary embodiment.

Accordingly, a height of the jig <NUM> is same as a height of the image formation surface of the medium <NUM> in a state where the medium <NUM> is in the recessed part <NUM> of the jig <NUM>. More specifically, a height from a table part <NUM> to the upper surface <NUM> of the jig <NUM> is same as a height from the table part <NUM> to a front surface <NUM> of the medium <NUM>, which is the image formation surface.

As in the first exemplary embodiment, a body of the jig <NUM> is made of an electrically conductive material. Accordingly, the jig <NUM> attached to the table part <NUM> is conductive with the table part <NUM> through a lower surface <NUM>. Furthermore, the jig <NUM> is conductive with the medium <NUM> inserted into the recessed part <NUM>. Accordingly, the front surface <NUM> of the medium <NUM>, which is the image formation surface, is connected to ground with the jig <NUM> and the table part <NUM> interposed therebetween.

Furthermore, the jig <NUM> according to the present exemplary embodiment has, on the upper surface <NUM>, a non-conductive layer <NUM> that keeps the jig <NUM> from becoming directly conductive with the intermediate transfer belt <NUM> and the backup roll <NUM>. The non-conductive layer <NUM> is a layer having lower electric conductivity than the medium <NUM>. As the electric conductivity of the non-conductive layer <NUM>, lower electric conductivity is more desirable, and the non-conductive layer <NUM> desirably has an insulation property. A material of the non-conductive layer <NUM> is not limited in particular, and can be, for example, an insulating resin such as a phenolic resin, ceramic such as alumina, glass, or the like.

In the present exemplary embodiment, when an attachment table <NUM> moves to the transfer position, the intermediate transfer belt <NUM> makes contact with the upper surface <NUM> of the jig <NUM> before making contact with the front surface <NUM> of the medium <NUM>. With this configuration, when the attachment table <NUM> moves to the transfer position, a shock caused when the intermediate transfer belt <NUM> makes contact with the front surface <NUM> of the medium <NUM> is lessened due to the jig <NUM> as compared with a case where the intermediate transfer belt <NUM> makes contact with the front surface <NUM> of the medium <NUM> without making contact with the jig <NUM>.

Furthermore, in the present exemplary embodiment, since the jig <NUM> has the non-conductive layer <NUM>, the intermediate transfer belt <NUM> makes contact with the non-conductive layer <NUM> provided on the upper surface <NUM> of the jig <NUM> in a case where the attachment table <NUM> moves to the transfer position in a state where a height of the attachment table <NUM> has been controlled so that the front surface <NUM> of the medium <NUM> makes contact with the intermediate transfer belt <NUM> with a strength appropriate for transfer of an image. This keeps the jig <NUM> from becoming directly conductive with the intermediate transfer belt <NUM> and the backup roll <NUM>, thereby keeping particles from being attached from the transfer surface of the intermediate transfer belt <NUM> to the upper surface <NUM> of the jig <NUM> by a transfer electric field.

Although the height of the upper surface <NUM> of the jig <NUM> is same as a height of the front surface <NUM> of the medium <NUM> in the example illustrated in <FIG>, for example, the height of the upper surface <NUM> of the jig <NUM> may be lower than the height of the front surface <NUM> of the medium <NUM> as in the first exemplary embodiment. In this case, a transfer electric field may be undesirably formed between the jig <NUM> and the intermediate transfer belt <NUM> and the backup roll <NUM> since a distance between the intermediate transfer belt <NUM> and the upper surface <NUM> of the jig <NUM> becomes short depending on the height control of the attachment table <NUM> although the intermediate transfer belt <NUM> and the upper surface <NUM> of the jig <NUM> are less likely to make contact with each other when the attachment table <NUM> moves to the transfer position. On the other hand, by providing the non-conductive layer <NUM> on the upper surface <NUM> of the jig <NUM> even in a case where the intermediate transfer belt <NUM> and the upper surface <NUM> of the jig <NUM> do not make contact with each other, particles are further kept from being attached from the transfer surface of the intermediate transfer belt <NUM> to the upper surface <NUM> of the jig <NUM>.

Next, a modification of the second exemplary embodiment is described. <FIG> and <FIG> illustrate a jig <NUM> and a medium <NUM> to which the modification of the second exemplary embodiment is applied, and <FIG> and <FIG> are views of the jig <NUM> and the medium <NUM> viewed from an upper side (intermediate transfer belt <NUM> side), and <FIG> and <FIG> are cross-sectional views of the jig <NUM> and the medium <NUM> taken along the transport direction at a central part in a width direction thereof. Note that constituent elements similar to those in the example illustrated in <FIG> are given identical reference signs in <FIG> and <FIG>, and detailed description thereof is omitted.

In the modification illustrated in <FIG>, an upper surface <NUM> of the jig <NUM> has, on a front end side in the transport direction relative to a recessed part <NUM>, an inclined surface 431a whose height decreases toward the front side in the transport direction and has, on a rear end side in the transport direction relative to the recessed part <NUM>, an inclined surface 431b whose height decreases toward the rear side in the transport direction, as with the jig <NUM> illustrated in <FIG> according to the first exemplary embodiment. Note that in this example, a height of a rear end portion of the inclined surface <NUM>1a that faces the recessed part <NUM> and a height of a front end portion of the inclined surface 431b that faces the recessed part <NUM> are same as a height of a front surface <NUM> of a medium <NUM> inserted into the recessed part <NUM> of the jig <NUM>.

According to the jig <NUM> illustrated in <FIG>, a non-conductive layer <NUM> is provided on the entire upper surface <NUM> including the inclined surface 431a and the inclined surface 431b. Furthermore, according to the jig <NUM> illustrated in <FIG>, the non-conductive layer <NUM> is provided not only on the upper surface <NUM>, but also on a front end side surface <NUM> located at a front end of the jig <NUM> in the transport direction and a rear end side surface <NUM> located at a rear end of the jig <NUM> in the transport direction.

In the example illustrated in <FIG>, the non-conductive layer <NUM> keeps the jig <NUM> from becoming directly conductive with the intermediate transfer belt <NUM> and the backup roll <NUM> even in a case where the attachment table <NUM> moves to the transfer position and the intermediate transfer belt <NUM> makes contact with the upper surface <NUM> of the jig <NUM>, as in the example illustrated in <FIG>. This keeps particles from being attached from the transfer surface of the intermediate transfer belt <NUM> to the upper surface <NUM> of the jig <NUM> by a transfer electric field.

Furthermore, in the example illustrated in <FIG>, even in a case where the intermediate transfer belt <NUM> makes contact with the front end side surface <NUM> located at the front end of the jig <NUM> when the attachment table <NUM> moves to the transfer position, the jig <NUM> is kept from becoming directly conductive with the intermediate transfer belt <NUM> and the backup roll <NUM> since the non-conductive layer <NUM> is provided on the front end side surface <NUM>.

Similarly, in the example illustrated in <FIG>, even in a case where the intermediate transfer belt <NUM> makes contact with the rear end side surface <NUM> located at the rear end of the jig <NUM> when the attachment table <NUM> moves from the transfer position toward the transport end position after an image is transferred onto the front surface <NUM> of the medium <NUM>, the jig <NUM> is kept from becoming directly conductive with the intermediate transfer belt <NUM> and the backup roll <NUM> since the non-conductive layer <NUM> is provided on the rear end side surface <NUM>.

This keeps particles from being attached from the transfer surface of the intermediate transfer belt <NUM> to the front end side surface <NUM> and the rear end side surface <NUM> of the jig <NUM> by a transfer electric field.

The modification illustrated in <FIG> is different from the example illustrated in <FIG> in shapes of the medium <NUM> and the jig <NUM>.

The medium <NUM> illustrated in <FIG> includes a flat plate part <NUM> having a flat plate shape having a rectangular front surface <NUM> and a rectangular rear surface <NUM> and a base part <NUM> having a rectangular parallelepiped shape protruding from a central part of the rear surface <NUM> of the flat plate part <NUM>. The flat plate part <NUM> and the base part <NUM> are made of a conductor, and the whole medium <NUM> has electric conductivity. In this example, the front surface <NUM> of the flat plate part <NUM> of the medium <NUM> is the image formation surface including a region where an image is to be formed.

Furthermore, the jig <NUM> illustrated in <FIG> has a recessed part <NUM> that holds the medium <NUM>. In this example, the recessed part <NUM> has a groove shape extending from one end to the other end of the jig <NUM> in the width direction. A length of the recessed part <NUM> along the transport direction is longer than a length of the base part <NUM> of the medium <NUM> along the transport direction and is shorter than a length of the flat plate part <NUM> of the medium <NUM> along the transport direction. An upper surface <NUM> of the jig <NUM> is divided into a front side and a rear side in the transport direction by the recessed part <NUM>. Furthermore, a length of the jig <NUM> in the transport direction, more specifically, a distance between a front end and a rear end of the upper surface <NUM> of the jig <NUM> is longer than a length of the flat plate part <NUM> of the medium <NUM> in the transport direction.

The base part <NUM> of the medium <NUM> is inserted into a space formed inside the recessed part <NUM> of the jig <NUM>, and the rear surface <NUM> of the medium <NUM> is placed on the upper surface <NUM> of the jig <NUM>. The upper surface <NUM> of the jig <NUM> and the rear surface <NUM> of the medium <NUM> make contact with each other, and thereby the jig <NUM> and the medium <NUM> become conductive with each other. Accordingly, the front surface <NUM> of the flat plate part <NUM> of the medium <NUM>, which is the image formation surface, is connected to ground with the jig <NUM> and the table part <NUM> interposed therebetween.

According to the jig <NUM> illustrated in <FIG>, a non-conductive layer <NUM> is provided on a portion of the upper surface <NUM> that does not make contact with the rear surface <NUM> of the flat plate part <NUM>.

With this configuration, the intermediate transfer belt <NUM> makes contact with the non-conductive layer <NUM> provided on the upper surface <NUM> of the jig <NUM> in a case where the attachment table <NUM> moves to the transfer position in a state where a height of the attachment table <NUM> has been controlled so that the front surface <NUM> of the flat plate part <NUM> of the medium <NUM> makes contact with the intermediate transfer belt <NUM> with a strength appropriate for transfer of an image. This keeps the jig <NUM> from becoming directly conductive with the intermediate transfer belt <NUM> and the backup roll <NUM>, thereby keeping particles from being attached from the transfer surface of the intermediate transfer belt <NUM> to the upper surface <NUM> of the jig <NUM> by a transfer electric field.

Next, the third exemplary embodiment of the present disclosure is described. Note that constituent elements similar to those in the first exemplary embodiment are given identical reference signs, and detailed description thereof is omitted.

In the third exemplary embodiment, a jig <NUM> is kept from becoming directly conductive with an intermediate transfer belt <NUM> and a backup roll <NUM> by controlling a timing of application of a voltage to the backup roll <NUM> by a controller <NUM> (see <FIG>).

<FIG> is a sequence diagram illustrating an example of a relationship between a timing of control by the controller <NUM> and a timing at which the medium <NUM> held by the jig <NUM> is transported to the transfer position. <FIG> illustrates an example of timings during a period for which an attachment table <NUM> moves from the preparation position to the transfer position and an image is transferred onto a medium <NUM>.

The controller <NUM> turns on a driving signal of a driving signal that moves the attachment table <NUM> as illustrated in <FIG> after adjusting a height of the attachment table <NUM> to a transfer execution height at the preparation position. This causes the attachment table <NUM> to move from the preparation position toward the transfer position along a transport rail <NUM> (see <FIG>).

Then, the controller <NUM> turns on an output signal for applying a transfer voltage to the backup roll <NUM> (see <FIG>) at a timing (a timing indicated by (b) in <FIG>) at which a front end (a front end of a front surface <NUM>) of the medium <NUM> held by the jig <NUM> attached to the attachment table <NUM> reaches the transfer position. As a result, a voltage of a predetermined magnitude is applied to the backup roll <NUM> by a power source <NUM>, and a transfer electric field is formed between the backup roll <NUM> and the medium <NUM>.

Then, the controller <NUM> turns off the output signal for applying the voltage to the backup roll <NUM> at a timing (a timing indicated by (c) in <FIG>) at which the medium <NUM> held by the jig <NUM> attached to the attachment table <NUM> passes the transfer position and a rear end (a rear end of the front surface <NUM>) of the medium <NUM> reaches the transfer position. This ends the application of the voltage to the backup roll <NUM>, and as a result, the transfer electric field is no longer formed between the backup roll <NUM> and the medium <NUM>.

Then, when the attachment table <NUM> reaches a fixing unit <NUM> (see <FIG>) after passing the transfer position, the controller <NUM> turns off the driving signal of the driving device that moves the attachment table <NUM>.

In the present exemplary embodiment, as a result of the control performed by the controller <NUM>, a voltage is applied to the backup roll <NUM> during a period between (b) and (c) in <FIG>, in other words, during a period for which the medium <NUM> is passing the transfer position and the front surface <NUM> of the medium <NUM> and the intermediate transfer belt <NUM> are in contact with each other. This makes it possible to transfer an image formed with particles on the intermediate transfer belt <NUM> onto the front surface <NUM> of the medium <NUM> by a transfer electric field formed between the backup roll <NUM> and the front surface <NUM> of the medium <NUM>.

Furthermore, in the present exemplary embodiment, as a result of the control performed by the controller <NUM>, no voltage is applied to the backup roll <NUM> during a period for which the intermediate transfer belt <NUM> and the front surface <NUM> of the medium <NUM> are not in contact with each other.

More specifically, in the present exemplary embodiment, no voltage is applied to the backup roll <NUM> during a period between (a) and (b) in <FIG>, in other words, during a period from a timing at which the front end (the front end of the upper surface <NUM>) of the jig <NUM> attached to the attachment table <NUM> reaches the transfer position to a timing at which the front end (the front end of the front surface <NUM>) of the medium <NUM> reaches the transfer position. Furthermore, in the present exemplary embodiment, no voltage is applied to the backup roll <NUM> during a period between (c) and (d) in <FIG>, in other words, during a period from a timing at which the rear end (the rear end of the front surface <NUM>) of the medium <NUM> reaches the transfer position to a timing at which the rear end (the rear end of the upper surface <NUM>) of the jig <NUM> passes the transfer position.

Furthermore, in the present exemplary embodiment, no voltage is applied to the backup roll <NUM> during a period for which the intermediate transfer belt <NUM> and the upper surface <NUM> of the jig <NUM> are in contact with each other.

Although the exemplary embodiments of the present disclosure have been described, the technical scope of the present disclosure is not limited to the above exemplary embodiments.

For example, although the image forming apparatus <NUM> forms a transfer electric field between the backup roll <NUM> and the image formation surface of the medium <NUM> by connecting the image formation surface of the medium <NUM> to ground with the jig <NUM> interposed therebetween and applying a predetermined voltage to the backup roll <NUM> by the power source <NUM> in the above exemplary embodiments, this is not restrictive. For example, the image forming apparatus <NUM> may form a transfer electric field between the backup roll <NUM> and the image formation surface of the medium <NUM> by connecting the backup roll <NUM> to ground and applying a voltage to the jig <NUM> and the table part <NUM>. In this case, for example, in the third exemplary embodiment, the controller <NUM> need just control a timing at which a voltage is applied to the jig <NUM> or the table part <NUM> instead of a timing at which a voltage is applied to the backup roll <NUM>.

In the present exemplary embodiment, it is desirable that the configuration of the jig <NUM> attached to the attachment table <NUM> be simple since the attachment table <NUM> of the transport mechanism <NUM> moves along the transport rail <NUM>. In a case where the configuration in which the image formation surface of the medium <NUM> is connected to ground with the jig <NUM> interposed therebetween and a predetermined voltage is applied to the backup roll <NUM> by the power source <NUM> is employed as in the above exemplary embodiments, it is unnecessary to connect a member such as a power source to the jig <NUM>. This may simplify the configuration of the jig <NUM> and the configuration of the attachment table <NUM> to which the jig <NUM> is attached.

Various changes and substitution of the configurations are encompassed within the present disclosure without departing from the scope of the technical idea of the present disclosure.

The foregoing description of the exemplary embodiments of the present disclosure has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure 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 disclosure and its practical applications, thereby enabling others skilled in the art to understand the disclosure for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the following claims.

According to the image forming apparatus according to the present invention, particles are less likely to be attached to the support unit than in a case where the support unit that supports the recording medium and the transfer unit are directly conductive with each other.

According to the image forming apparatus according to appended claim <NUM>, particles are less likely to be attached to the support unit than in a case where the support unit makes contact with the transfer unit.

According to the image forming apparatus according to appended claim <NUM>, particles are less likely to be attached to the support unit than in a case where the height of the support unit is equal to or higher than the height of the image formation surface of the recording medium.

According to the image forming apparatus according to the present invention, particles are less likely to be attached to the support unit than in a case where the support unit does not have a non-conductive portion on the portion that makes contact with the transfer unit.

According to the image forming apparatus according to appended claim <NUM>, an electric field can be formed between the transfer unit and the image formation surface of the recording medium by using the support unit.

According to the image forming apparatus according to appended claim <NUM>, particles are less likely to be attached to the support unit than in a case where a voltage is applied during a period for which the transfer unit and the image formation surface of the recording medium are not in contact with each other.

According to the image forming apparatus according to appended claim <NUM>, particles are less likely to be attached to a front side of the support unit than in a case where a voltage is applied before the transfer unit and the image formation surface of the recording medium make contact with each other.

Claim 1:
An image forming apparatus (<NUM>) comprising:
a transport unit (<NUM>) that transports a recording medium (<NUM>);
a transfer unit (<NUM>) that transfers an image formed with particles onto an image formation surface of the recording medium (<NUM>) transported by the transport unit (<NUM>) by an electric field formed between the transfer unit (<NUM>) and the image formation surface by making contact with the image formation surface; and
a support unit (<NUM>) that supports the recording medium (<NUM>), is transported to the transfer unit (<NUM>) together with the recording medium (<NUM>) by the transport unit (<NUM>), and is not directly conductive with the transfer unit (<NUM>),
the image forming apparatus (<NUM>) being characterized in that:
the support unit (<NUM>) makes contact with the transfer unit (<NUM>) and has, on a portion that makes contact with the transfer unit (<NUM>), a non-conductive layer having lower electric conductivity than the image formation surface of the recording medium (<NUM>).