Patent Description:
<CIT> discloses a printer that forms an image on a print surface of a disc that is placed on a transport table and is transported by transferring a toner image given to a transfer belt onto the print surface.

<CIT> discloses a shaping system adopting a method involving independently forming images of respective layers and sequentially stacking the images on a stage to obtain a three-dimensional shaping object. <CIT> discloses an image forming apparatus representing prior art pertinent to the claimed invention.

Some image forming apparatuses transfer an image onto a recording medium by bringing a transfer unit into contact with the recording medium that is transported.

In such image forming apparatuses, a support unit such as a jig that supports a recording medium may be provided in order to keep misregistration of the recording medium from occurring due to a shock caused when the transfer unit makes contact with the recording medium. However, in a case where a recording medium whose height changes from a front end toward a rear end in a transport direction is supported by a support unit, a region where an image can be formed on the recording medium may undesirably become narrow.

Accordingly, it is an object of the present invention to provide a technique of keeping a region where an image can be formed on a recording medium from becoming narrow as compared with a case where contact of a transfer unit with an image formation surface is hindered by a support unit that supports the recording medium.

The present invention is provided by the appended claims. The following disclosure serves a better understanding of the present invention.

Exemplary embodiments of the present disclosure are described in detail below with reference to the attached drawings. An image forming apparatus according to the present exemplary embodiments 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 embodiments. 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 embodiments, 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. Apparatus Configuration.

<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 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 is a single controller that controls operation of the whole image forming apparatus <NUM> in this example, the controller may be controllers 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>. Configuration of Transfer Unit <NUM>.

<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.

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>. Note that the transport rail <NUM> and the attachment table <NUM> are an example of a transport unit.

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 a memory of a 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. Configuration of Medium Attaching Detaching Unit <NUM>.

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>, which is an example of a cleaning unit, 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>.

In the image forming apparatus <NUM> according to the present exemplary embodiment, it is assumed that the medium <NUM> on which an image is to be printed can have various thicknesses and shapes, as described above.

<FIG> illustrates an example of a shape of the medium <NUM> on which an image is to be formed by the image forming apparatus <NUM> according to the present exemplary embodiment and is a perspective view of the medium <NUM>.

The medium <NUM> has a front surface <NUM> and a rear surface <NUM> that are curved so as to protrude upward and have a rectangular shape when viewed from an upper side, a pair of first side surfaces <NUM> that connect opposed sides of the front surface <NUM> and the rear surface <NUM>, and a pair of second side surfaces <NUM> that connect opposed sides of the front surface <NUM> and the rear surface <NUM>, and has a plate shape curved so as to protrude upward 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, is made of a conductor.

The medium <NUM> having a shape like the one illustrated in <FIG> is, for example, attached to the jig <NUM> (see <FIG>) so that the first side surfaces <NUM> extend along a transport direction in which the medium <NUM> is transported by the transport mechanism <NUM>. Specifically, the medium <NUM> is attached to the jig <NUM> so that the rear surface <NUM> faces downward.

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 while passing the transfer position.

In a case where the medium <NUM> is attached to the jig <NUM> so that the first side surfaces <NUM> extend along the transport direction in which the medium <NUM> is transported by the transport mechanism <NUM>, one of the second side surfaces <NUM> is located at a front end in the transport direction, and the other one of the second side surfaces <NUM> is located at a rear end in the transport direction. Hereinafter, the second side surface <NUM> located at a front end in the transport direction and the second side surface <NUM> located at a rear end in the transport direction when the medium <NUM> is attached to the jig <NUM> are sometimes referred to as a front end surface <NUM> and a rear end surface <NUM>, respectively.

In a case where the medium <NUM> is attached to the jig <NUM>, a height of the front surface <NUM>, which is the image formation surface, changes from the front end toward the rear end in the transport direction. Specifically, the height of the front surface <NUM> of the medium <NUM> decreases toward the front end and the rear end in the transport direction. Specifically, since the medium <NUM> is curved so as to protrude upward, in a case where the medium <NUM> is attached to the jig <NUM>, a height of the front end and a height of the rear end in the transport direction of the front surface <NUM>, which is the image formation surface, (that is, a height of the front end surface <NUM> and a height of the rear end surface <NUM>) are lower than a height of a central part in the transport direction of the front surface <NUM>.

In a case where the medium <NUM> having the front surface <NUM> (image formation surface) whose height changes is attached to the jig <NUM> and an image is formed on the front surface <NUM> of the medium <NUM> by the image forming apparatus <NUM>, contact of the intermediate transfer belt <NUM> with the front surface <NUM> of the medium <NUM> may be undesirably hindered by the jig <NUM> depending on a shape of the jig <NUM> to which the medium <NUM> is attached.

<FIG> is a view for explaining a comparative example for the present exemplary embodiment and illustrates a state where contact of the intermediate transfer belt <NUM> with the front surface <NUM> of the medium <NUM> is hindered by the jig <NUM>.

In the example illustrated in <FIG>, the jig <NUM> supports the medium <NUM> in contact with the front end surface <NUM>, which is the front end of the medium <NUM> in the transport direction, and the rear end surface <NUM>, which is the rear end of the medium <NUM> in the transport direction. Furthermore, a height of the upper surface <NUM> of the jig <NUM> is higher than the height of the front end surface <NUM> and the height of the rear end surface <NUM> of the medium <NUM>. Specifically, in the example illustrated in <FIG>, the jig <NUM> has a portion that protrudes upward (toward the intermediate transfer belt <NUM>) beyond the front end surface <NUM> and the rear end surface <NUM> of the jig <NUM>.

In this case, when 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 strength appropriate for transfer of an image, the transfer surface of 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>. In this case, the jig <NUM> hinders the transfer surface of the intermediate transfer belt <NUM> from making contact with the front end (a portion indicated by a in <FIG>) of the front surface <NUM> of the medium <NUM>.

Then, the transfer surface of the intermediate transfer belt <NUM> makes contact with the central part of the front surface <NUM> of the medium <NUM>. After an image is transferred onto the front surface <NUM>, the attachment table <NUM> further moves along the transport direction. As a result, the transfer surface of the intermediate transfer belt <NUM> makes contact with the upper surface <NUM> of the jig <NUM> without making contact with the rear end (a portion indicated by b in <FIG>) of the front surface <NUM> of the medium <NUM>. In this case, the jig <NUM> hinders the transfer surface of the intermediate transfer belt <NUM> from making contact with the rear end (the portion indicated by b in <FIG>) of the front surface <NUM> of the medium <NUM>.

In a case where the jig <NUM> hinders the intermediate transfer belt <NUM> from making contact with the front surface <NUM> of the medium <NUM>, which is the image formation surface, an image cannot be transferred from the intermediate transfer belt <NUM> onto the front end and the rear end of the front surface <NUM> of the medium <NUM>, and therefore a region where an image can be formed on the front surface <NUM> of the medium <NUM> becomes narrow. Furthermore, since a region where an image can be formed on the front surface <NUM> of the medium <NUM> becomes narrow, it becomes difficult to form an image having no frame (frame-less image) on the upper surface of the medium <NUM>.

On the other hand, in the present exemplary embodiment, the jig <NUM> supports the medium <NUM> so as not to hinder the intermediate transfer belt <NUM> from making contact with the front surface <NUM>, which is the image formation surface, and therefore a region where an image can be formed on the medium <NUM> is kept from becoming narrow.

The shape and the like of the jig <NUM> according to the present exemplary embodiment are described in detail below.

<FIG> illustrate the jig <NUM> and the medium <NUM> to which the first exemplary embodiment is applied, and <FIG> is a view of the jig <NUM> and the medium <NUM> viewed from an upper side (the intermediate transfer belt <NUM> side), and <FIG> is a cross-sectional view of the jig <NUM> and the medium <NUM> taken along the transport direction at a central part in a width direction crossing the transport direction.

Note that the shape of the medium <NUM> is similar to that illustrated in <FIG>.

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 a flat plate part <NUM> that has a flat plate shape having a rectangular upper surface <NUM> and a rectangular lower surface <NUM>, and the medium <NUM> is placed on the upper surface <NUM>. The jig <NUM> is attached to the table part <NUM> so that the lower surface <NUM> of the flat plate part <NUM> faces the table part <NUM>, and is conductive with the table part <NUM> through the lower surface <NUM>.

Furthermore, the jig <NUM> has support walls <NUM> that protrude upward from the upper surface <NUM> of the flat plate part <NUM>, extend along the transport direction, and make contact with the first side surfaces <NUM> of the medium <NUM>. The medium <NUM> is inserted into a space between the pair of support walls <NUM> of the jig <NUM>, and the medium <NUM> is supported by the support walls <NUM>. As described above, the medium <NUM> is supported by 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> (the front end surface <NUM> and the rear end surface <NUM>) extend along the width direction of the medium <NUM> orthogonal to the transport direction. The support walls <NUM> may be given a pressure in the width direction so as to press the first side surfaces <NUM> of the medium <NUM> although this is not illustrated. In this case, misregistration of the medium <NUM> in the transport direction is less likely to be caused by a shock when the attachment table <NUM> moves to the transfer position and the intermediate transfer belt <NUM> (see <FIG>) makes contact with the medium <NUM>.

The jig <NUM> according to the present exemplary embodiment does not have a portion that protrudes upward, that is, toward the intermediate transfer belt <NUM> beyond the front surface <NUM> of the medium <NUM>, which is the image formation surface, in a case where the medium <NUM> is attached to the jig <NUM>. More specifically, the height of the support walls <NUM> that support the first side surfaces <NUM> of the medium <NUM> is lower than the height of the front surface <NUM> of the medium <NUM>, which is the image formation surface, in a case where the medium <NUM> is attached to the jig <NUM>.

With this configuration, the intermediate transfer belt <NUM> makes contact with the front surface <NUM> of the medium <NUM> without being hindered by 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 strength appropriate for transfer of an image. Accordingly, an image is transferred from the intermediate transfer belt <NUM> onto the front surface <NUM> of the medium <NUM> from the front end to the rear end in the transport direction as the attachment table <NUM> is moved by the transport mechanism <NUM>.

As described above, in the present exemplary embodiment, the jig <NUM> does not have a portion that protrudes toward the intermediate transfer belt <NUM> beyond the front surface <NUM> of the medium <NUM>, which is the image formation surface, and therefore a region where an image can be formed on the front surface <NUM> of the medium <NUM> is kept from becoming narrow as compared with a case where the jig <NUM> has a portion that protrudes toward the intermediate transfer belt <NUM> beyond the front surface <NUM> of the medium <NUM>.

From another perspective, the jig <NUM> according to the present exemplary embodiment does not make contact with the intermediate transfer belt <NUM> during a period in which an image is being transferred from the intermediate transfer belt <NUM> onto the front surface <NUM> of the medium <NUM> as the attachment table <NUM> is moved by the transport mechanism <NUM> after the attachment table <NUM> moves to the transfer position and the intermediate transfer belt <NUM> makes contact with the front end of the front surface <NUM> of the medium <NUM>. This keeps a region where an image can be formed on the front surface <NUM> of the medium <NUM> from becoming narrow as compared with a case where the jig <NUM> makes contact with the intermediate transfer belt <NUM> during the period in which an image is being transferred from the intermediate transfer belt <NUM> onto the front surface <NUM> of the medium <NUM>.

A length of the support walls <NUM> of the jig <NUM> according to the present exemplary embodiment along the transport direction is shorter than a length of the medium <NUM> along the transport direction. With this configuration, for example, the support walls <NUM> are less likely to protrude toward the front side beyond the front end surface <NUM> of the medium <NUM> or toward the rear side beyond the rear end surface <NUM> of the medium <NUM> in a case where the medium <NUM> is attached to the jig <NUM>, as compared with a case where the length of the support walls <NUM> along the transport direction is longer than the length of the medium <NUM> along the transport direction. Specifically, the support walls <NUM> of the jig <NUM> according to the present exemplary embodiment support the first side surfaces <NUM> of the medium <NUM> on a rear side relative to the front end surface <NUM>, which is the front end of the medium <NUM> in the transport direction.

In this case, in a case where the attachment table <NUM> moves to the transfer position, the intermediate transfer belt <NUM> is less likely to make contact with the support walls <NUM>, and contact of the intermediate transfer belt <NUM> with the front surface <NUM> of the medium <NUM> is less likely to be hindered. Furthermore, a region where an image can be formed on the front surface <NUM> of the medium <NUM> is kept from becoming narrow.

Furthermore, the jig <NUM> according to the present exemplary embodiment does not support the front end surface <NUM>, which is the front end of the medium <NUM> in the transport direction. The jig <NUM> does not make contact with the intermediate transfer belt <NUM> before the intermediate transfer belt <NUM> makes contact with the front end of the medium <NUM>. As a result, contact of the intermediate transfer belt <NUM> with the front end of the front surface <NUM> of the medium <NUM> is less likely to be hindered in a case where the attachment table <NUM> moves to the transfer position. Furthermore, a region where an image can be formed on the front surface <NUM> of the medium <NUM> is further kept from becoming narrow.

Furthermore, the jig <NUM> according to the present exemplary embodiment does not support the rear end surface <NUM>, which is the rear end of the medium <NUM> in the transport direction. As a result, contact of the intermediate transfer belt <NUM> with the rear end of the front surface <NUM> of the medium <NUM> is less likely to be hindered in a case where the attachment table <NUM> moves to the transfer position. Furthermore, a region where an image can be formed on the front surface <NUM> of the medium <NUM> is further kept from becoming narrow.

As described above, the height of the front surface <NUM> of the medium <NUM> attached to the jig <NUM> according to the present exemplary embodiment decreases toward the front end in the transport direction. In this case, in a case where the attachment table <NUM> moves to the transfer position and the intermediate transfer belt <NUM> makes contact with the front end of the front surface <NUM> of the medium <NUM>, a pressure applied from the intermediate transfer belt <NUM> to the medium <NUM> is smaller than in a case where the height of the front surface <NUM> does not decrease toward the front end in the transport direction.

Furthermore, the height of the front surface <NUM> of the medium <NUM> gradually increases from the front end toward a rear side in the transport direction. Accordingly, the pressure applied from the intermediate transfer belt <NUM> to the medium <NUM> gradually increases as the attachment table <NUM> further moves in the transport direction after the intermediate transfer belt <NUM> makes contact with the front end of the front surface <NUM> of the medium <NUM>.

With this configuration, a shock given to the medium <NUM> when the intermediate transfer belt <NUM> makes contact with the front end of the medium <NUM> is more likely to be lessened than in a case where the height of the front surface <NUM> of the medium <NUM> does not decrease toward the front end in the transport direction.

Therefore, even in a case where the jig <NUM> does not support the front end surface <NUM> and the rear end surface <NUM> of the medium <NUM>, misregistration of the medium <NUM> is less likely to be caused by a shock given to the medium <NUM> when the intermediate transfer belt <NUM> makes contact with the front end of the medium <NUM>.

Next, a second exemplary embodiment of the present disclosure is described below. Note that constituent elements similar to those in the first exemplary embodiment are given identical reference signs, and detailed description thereof is omitted. This embodiment is not covered by the claims but it serves a better understanding of the present invention.

<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 at a central part in a width direction.

The jig <NUM> according to the present exemplary embodiment has a rectangular upper surface <NUM> that faces the intermediate transfer belt <NUM> when transported to a 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 a table part <NUM> so that the lower surface <NUM> faces the table part <NUM>, and 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 in which the medium <NUM> is transported by a 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>. The medium <NUM> is inserted into the recessed part <NUM> so that first side surfaces <NUM> extend along the transport direction in which the medium <NUM> is transported by the transport mechanism <NUM>.

The recessed part <NUM> of the jig <NUM> has an inner peripheral surface that matches a 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 a 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.

When the medium <NUM> is inserted into the recessed part <NUM>, the jig <NUM> supports the first side surfaces <NUM>, a front end surface <NUM>, and a rear end surface <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> of the recessed part <NUM> of the jig <NUM> make contact with the first side surfaces <NUM> of the medium <NUM>. Furthermore, the second inner peripheral surfaces <NUM> of the recessed part <NUM> of the jig <NUM> make contact with the front end surface <NUM> and the rear end surface <NUM> of the medium <NUM>. Furthermore, the bottom surface <NUM> of the recessed part <NUM> of the jig <NUM> makes contact with a rear surface <NUM> of the medium <NUM>.

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

A height of the recessed part <NUM> of the jig <NUM> according to the present exemplary embodiment from the bottom surface <NUM> to the upper surface <NUM> is lower than a height of the front end surface <NUM> and the rear end surface <NUM> of the medium <NUM>. Specifically, a height of the second inner peripheral surfaces <NUM> of the jig <NUM> that support the medium <NUM> in contact with the front end surfaces <NUM> and the rear end surface <NUM> is lower than the height of the front end surface <NUM> and the rear end surface <NUM>.

With the configuration, the intermediate transfer belt <NUM> makes contact with the front surface <NUM> of the medium <NUM> without being hindered by the jig <NUM> in a case where an 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 strength appropriate for transfer of an image. As the attachment table <NUM> is moved by the transport mechanism <NUM>, an image is transferred from the intermediate transfer belt <NUM> onto the front surface <NUM> of the medium <NUM> from a front end to a rear end in the transport direction.

As described above, in the present exemplary embodiment, a region where an image can be formed on the front surface <NUM> of the medium <NUM> is kept from becoming narrow as compared with a case where the height of the second inner peripheral surfaces <NUM> that support the medium <NUM> in contact with the front end surface <NUM> and the rear end surface <NUM> of the medium <NUM> is higher than the height of the front end surface <NUM> and the rear end surface <NUM>.

Furthermore, as in the first exemplary embodiment, the jig <NUM> according to the present exemplary embodiment does not make contact with the intermediate transfer belt <NUM> during a period in which an image is being transferred from the intermediate transfer belt <NUM> onto the front surface <NUM> of the medium <NUM> as the attachment table <NUM> is moved by the transport mechanism <NUM> after the attachment table <NUM> moves to the transfer position and the intermediate transfer belt <NUM> makes contact with the front end of the front surface <NUM> of the medium <NUM>. As a result, a region where an image can be formed on the front surface <NUM> of the medium <NUM> is kept from becoming narrow as compared with a case where the jig <NUM> makes contact with the intermediate transfer belt <NUM> during the period in which an image is being transferred from the intermediate transfer belt <NUM> onto the front surface <NUM> of the medium <NUM>.

Furthermore, the jig <NUM> according to the present exemplary embodiment supports the medium <NUM> in contact with the front end surface <NUM>, which is the front end of the medium <NUM> in the transport direction, and the rear end surface <NUM>, which is the rear end of the medium <NUM> in the transport direction, unlike the first exemplary embodiment. In other words, the jig <NUM> according to the present exemplary embodiment supports the medium <NUM> in the transport direction.

With this configuration, misregistration of the medium <NUM> in the transport direction is less likely to be caused by a shock given to the medium <NUM> when the intermediate transfer belt <NUM> makes contact with the front end of the medium <NUM> than in a case where the jig <NUM> does not support the front end surface <NUM> or the rear end surface <NUM> of the medium <NUM>.

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

For example, although the image forming apparatus <NUM> is configured such that a transfer electric field is formed 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 embodiment, 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> or the table part <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.

Furthermore, although a case where the medium <NUM> whose front surface <NUM>, which is the image formation surface, is a curved surface protruding upward is used has been illustrated in the above exemplary embodiments, the shape of the medium <NUM> is not limited to this. The medium <NUM> is not limited to a specific shape as long as the height of the front surface <NUM>, which is the image formation surface, changes from the front end toward the rear end in the transport direction in a case where the medium <NUM> is attached to the jig <NUM>. For example, the medium <NUM> may have a shape such that the height of the front surface <NUM> gradually increases from the front end toward the rear end or may have a shape such that the height of the front surface <NUM> gradually decreases from the front end toward the rear end. Furthermore, the front surface <NUM> of the medium <NUM> may be a curved surface whose height continuously and gradually changes as in the present exemplary embodiment, may be a flat surface, or may be a combination of a flat surface and a curved surface.

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

Claim 1:
An image forming apparatus (<NUM>) comprising:
a transport unit (<NUM>, <NUM>) configured to transport a recording medium (<NUM>) having an image formation surface (<NUM>) whose height changes from a front end toward a rear end in a transport direction;
a transfer unit (<NUM>) configured to transfer an image onto the image formation surface (<NUM>) of the recording medium (<NUM>) transported by the transport unit (<NUM>, <NUM>) by making contact with the image formation surface (<NUM>); and
a support unit (<NUM>) configured to support the recording medium (<NUM>) without hindering contact of the transfer unit (<NUM>) with the image formation surface (<NUM>) and configured to be transported together with the recording medium (<NUM>) by the transport unit (<NUM>, <NUM>),
wherein the support unit (<NUM>) is configured to support a side surface (<NUM>) of the recording medium (<NUM>) that crosses the image formation surface (<NUM>) and extends along the transport direction in which the recording medium (<NUM>) is transported by the transport unit (<NUM>, <NUM>), and has a height equal to or lower than a height of the image formation surface (<NUM>) of the recording medium (<NUM>),
the image forming apparatus (<NUM>) being characterized in that:
the support unit (<NUM>) is configured to support the side surface (<NUM>) of the recording medium (<NUM>) whose height decreases toward the front end and not support a front end surface (<NUM>) and/or a rear end surface (<NUM>) of the recording medium (<NUM>).