Patent Description:
The transfer transport apparatus described in <CIT> is a transfer sheet transport apparatus of a recording apparatus in which a recording head having a light emitting device array and an imaging system is moved at a constant speed in a substantially bus direction of a photoconductor drum which rotates at a constant speed, the photoconductor drum is spirally scanned to form a latent image, and a toner image obtained by developing the latent image is transferred to a transfer sheet. The transfer sheet transport apparatus includes: a pair of endless chains or belts transported in a direction perpendicular to the axis of the photoconductor drum; a gripper unit that is fixed to the pair of endless chains or belts by respective pins on both ends, and transports a transfer sheet by gripping the front edge thereof; and a unit that variably controls the relative positional relationship in the transport direction of the pair of chains or belts. Before the transfer sheet is transported to a transfer position, the orientation of the gripper unit is tilted by an angle equal to the angle of the main scanning direction of spiral recording on the photoconductor drum with respect to the drum circumferential direction, thus the transfer sheet transport apparatus transports the transfer sheet with the transfer sheet tilted.

<CIT> discloses a carrying device for carrying a recording medium such as a sheet, an image forming apparatus, and a recording medium carrying method. The image forming apparatus includes a leading end gripper and a trailing end gripper provided on a drum. The leading end gripper is moved by a leading end gripper driving mechanism. The trailing end gripper switches between a standby position where this gripper is stopped relatively to the rotating drum and a grip position where this gripper rotates with the drum. The leading end gripper and a recording medium pass through an inside of the trailing end gripper stopped in the standby position. If a trailing end of the recording medium reaches the trailing end gripper, the trailing end gripper is released and switches to the grip position. Thus, the trailing end of the medium is held on the drum by the trailing end gripper. The trailing end gripper moves in a rotating direction of the drum while continuing nipping the trailing end of the medium.

Accordingly, it is an object of the present invention to provide an image forming apparatus capable of being downsized, as compared with a configuration in which the sheet feed direction and the sheet discharge direction are the same direction.

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

According to a first aspect of the present disclosure, there is provided an image forming apparatus including, inter alia, a holding unit that holds a recording medium transported; a circumferential rotation unit that circumferentially rotates with the holding unit fixed, and constitutes part of a transport path along which the recording medium is transported; an image former that forms an image on the recording medium at an image formation position on a circumferential rotational path of the circumferential rotation unit; a pass point at which the recording medium is passed on the circumferential rotational path; and a receiving point which is provided on a same side as the pass point with respect to the image formation position, and at which the recording medium is received from the circumferential rotational path.

An image forming apparatus according to a second aspect is the image forming apparatus according to the first aspect, in which the pass point is disposed below the receiving point.

An image forming apparatus according to a third aspect is the image forming apparatus according to the second aspect, in which the circumferential rotational path is configured to include an upwardly inclined path along which the recording medium passes through the image former.

An image forming apparatus according to a fourth aspect is the image forming apparatus according to any one of the first to third aspects, in which the circumferential rotational path is configured to pass through a fixing unit that fixes an image to the recording medium at a fixing position provided downstream of the image former, and the fixing position is placed above the image formation position on the circumferential rotational path.

An image forming apparatus according to a fifth aspect is the image forming apparatus according to the fourth aspect, in which a position adjuster that performs position adjustment on the recording medium is disposed below the fixing position on the transport path for the recording medium, and between the fixing position and the image formation position in a horizontal direction.

An image forming apparatus according to a sixth aspect is the image forming apparatus according to any one of the first to fifth aspects, further including a position adjuster that performs position adjustment on the recording medium. The image forming apparatus is formed of a plurality of units, and the image former, the circumferential rotation unit, and the position adjuster are disposed in a same unit.

An image forming apparatus according to a seventh aspect is the image forming apparatus according to the sixth aspect, in which the circumferential rotational path has an inclined section which is inclined downward from the receiving point to the pass point, a space is formed between the inclined section and the transport path toward the pass point, and the position adjuster is disposed in the space.

An image forming apparatus according to an eighth aspect is the image forming apparatus according to any one of the first to seventh aspects, in which the circumferential rotation unit is mounted on both ends of the holding unit in a width direction of the recording medium transported.

An image forming apparatus according to a ninth aspect includes, inter alia, a holding unit that extends in a width direction of a recording medium transported, and holds the recording medium; and a circumferential rotation unit that circumferentially rotates with the holding unit fixed, transports the recording medium to an image former that forms an image on the recording medium, and reverses front and back of the recording medium on a circumferential rotational path.

An image forming apparatus according to a tenth aspect is the image forming apparatus according to the ninth aspect, in which the circumferential rotation unit passes through the image former in a process of reversing the front and back of the recording medium.

An image forming apparatus according to an eleventh aspect is the image forming apparatus according to the ninth or tenth aspect, in which the circumferential rotation unit configurates part of a back surface-side transport path for forming an image of the back of the recording medium.

An image forming apparatus according to a twelfth aspect is the image forming apparatus according to any one of the ninth to eleventh aspects, further including: a merge path provided upstream of the circumferential rotational path on a transport path for the recording medium, the merge path in which a transport path for a front surface of the recording medium and a transport path for a back surface of the recording medium are merged; and a position adjuster that is provided in the merge path, and performs position adjustment on the recording medium.

In the image forming apparatus according to the first aspect, the overall apparatus can be downsized, as compared with a configuration in which the sheet feed direction and the sheet discharge direction are the same direction.

In the image forming apparatus according to the second aspect, the sheet discharge path is easily disposed at an upper position, as compared with a configuration in which the pass point is placed above the receiving point.

In the image forming apparatus according to the third aspect, the sheet discharge path after passing the image former can be disposed above the sheet feed path before passing the image former, as compared with a configuration in which a partial path, passing the image former, on the circumferential rotational path is disposed horizontally.

In the image forming apparatus according to the fourth aspect, the exhaust heat generated in the fixing unit is unlikely to transfer to the image formation position, as compared with a configuration in which the fixing unit is disposed below the image formation position.

In the image forming apparatus according to the fifth aspect, the overall apparatus can be downsized, as compared with a configuration in which the position adjuster is disposed at the same height as the fixing position or disposed outside the range between the fixing position and the image formation position in a horizontal direction.

In the image forming apparatus according to the sixth aspect, adjustment of the position adjuster at the time of installation of the image forming apparatus can be simplified, as compared with a configuration in which the position adjuster is disposed in a unit different from the unit in which the image former and the circumferential rotation unit are disposed.

In the image forming apparatus according to the seventh aspect, in a configuration in which a space is formed between the circumferential rotational path and the transport path, the positional accuracy of the recording medium transported to the pass point is increased, as compared with a configuration in which the position adjuster is disposed upstream of the space in the transport direction of the recording medium.

In the image forming apparatus according to the eighth aspect, inclination of the recording medium in the width direction can be reduced, as compared with a configuration in which the circumferential rotation unit is mounted only on a central portion of the holding unit in the width direction.

In the image forming apparatus according to the ninth aspect, the overall apparatus can be downsized, as compared with a configuration in which the circumferential rotation unit that reverses the front and back of the recording medium is provided separately from the circumferential rotational path.

In the image forming apparatus according to the tenth aspect, the overall apparatus can be downsized, as compared with a configuration in which the position for the process of reversing the front and back of the recording medium, and the position of passage of the recording medium through the image former are separately provided on the circumferential rotational path.

In the image forming apparatus according to the eleventh aspect, the overall apparatus can be downsized, as compared with a configuration in which the circumferential rotation unit and the back surface-side transport path are provided separately.

In the image forming apparatus according to the twelfth aspect, the overall apparatus can be downsized, as compared with a configuration in which the merge path and the position adjuster are provided separately.

An image forming apparatus (simply referred to as an "apparatus" as needed) according to a first exemplary embodiment of the present disclosure will be described with reference to <FIG>. Note that an arrow UP illustrated in the drawings is a vertical direction which indicates the apparatus upper direction. In addition, as illustrated in <FIG>, an arrow RH is a horizontal direction which indicates the rightward when facing the apparatus. When the up and down direction is specified without an assumption in the following description, the direction indicates the up and down direction of the apparatus illustrated in <FIG>. When the right and left direction is specified without an assumption in the following description, the direction indicates the right (= R) or the left (= L) direction when facing the apparatus illustrated in <FIG>. In addition, when the depth direction (= near and far) is specified without an assumption in the following description, the direction indicates the depth direction when facing the apparatus illustrated in <FIG>.

First, the configuration of the image forming apparatus <NUM> will be described. <FIG> is a front view illustrating the outline of the image forming apparatus <NUM> according to the exemplary embodiment.

As illustrated in <FIG>, the image forming apparatus <NUM> includes: a unit 10A disposed on the right side of <FIG>; a unit 10B disposed on the left side of the unit 10A in <FIG>; and a unit 10C disposed on the left side of the unit 10B in <FIG>. The unit 10B and the unit 10C store sheets of paper P (= correspond to an example of a recording medium) for image recording, and include sheet trays <NUM> that supply sheets of paper P to the unit A. In addition, the unit 10C includes a sheet discharge tray <NUM>. The unit 10A includes an image former that forms an image on the sheet of paper P. The image former includes an image forming unit <NUM> to form an image by an electrophotographic system, an intermediate transfer belt <NUM> to carry an image formed, and an intermediate transfer unit <NUM> to be mounted on and support the intermediate transfer belt <NUM>. In addition, the image forming apparatus <NUM> is provided with a transfer body <NUM> on the lower left side of the intermediate transfer unit <NUM>, the transfer body <NUM> being configured to transfer an image from the intermediate transfer unit <NUM> to the sheet of paper P.

The contact section between the intermediate transfer belt <NUM> and the transfer body <NUM> is the later-described second transfer position <NUM> (= corresponds to an example of an image formation position). At the second transfer position <NUM>, a toner image formed by the image forming unit <NUM> is transferred to the front surface of the sheet of paper P via the intermediate transfer belt <NUM> mounted on the intermediate transfer unit <NUM>.

The image forming apparatus <NUM> includes multiple image forming units <NUM> for respectively forming toner images of each color. In the exemplary embodiment, a total of four image forming units corresponding to respective colors are provided: a yellow image forming unit 12Y, a magenta image forming unit <NUM>, a cyan image forming unit 12C, and a black image forming unit <NUM>.

Here, in the exemplary embodiment, yellow (= Y), magenta (= M), cyan (= C), and black (= K) are basic colors for outputting color images. In the following description, when the colors of the image forming units <NUM> do not need to be distinguished, each image forming unit <NUM> is simply referred to as an "image forming unit <NUM>", and a description is given with the symbols of Y, M, C and K omitted as appropriate, each of which represents an image forming unit of a corresponding color.

The toner image former <NUM> of each color basically has a similar configuration except for the type of toner. As illustrated in <FIG>, each image forming unit <NUM> includes a cylindrical photoconductor <NUM> which rotates, and a charger <NUM> that charges the photoconductor <NUM>. In addition, the image forming unit <NUM> includes an exposure device <NUM> that radiates light for exposure to the charged photoconductor <NUM> to form an electrostatic latent image; and a developing device <NUM> that develops the electrostatic latent image with a developer containing toner, as an image formed with toner. In addition, a cleaner <NUM> is provided to remove the remaining toner on the front surface of the photoconductor <NUM> after toner is transferred from the photoconductor <NUM> to the intermediate transfer belt <NUM>.

The photoconductor <NUM> of each color is configured to come into contact with the outer circumferential surface of the intermediate transfer belt <NUM>. In addition, as illustrated in <FIG>, the image forming units <NUM> corresponding to yellow, magenta, cyan, black are disposed side by side from the upstream side to the downstream side in the circumferential rotation direction (= the direction of arrow X in <FIG>) of the intermediate transfer belt <NUM>.

The intermediate transfer unit <NUM> includes first transfer rolls <NUM> disposed to be opposed to respective image forming units <NUM> of each color; and a back-up roll <NUM> disposed to be opposed to the transfer body <NUM>. The details of the transfer body <NUM> will be described below.

As illustrated in <FIG>, the intermediate transfer belt <NUM> is formed in an endless shape. The intermediate transfer belt <NUM> is wound on multiple rolls <NUM> to have its posture fixed. In the exemplary embodiment, the posture of the intermediate transfer belt <NUM> is an approximately obtuse triangular shape which is long in the apparatus width direction in a front view, and has a projecting obtuse angle downward. Of the multiple rolls <NUM>, one roll which is not illustrated has a function of rotating the intermediate transfer belt <NUM> in the direction of arrow X by power of a motor which is not illustrated. The intermediate transfer belt <NUM> is rotated in the direction of the arrow X, thereby transporting a first transferred image to the later-described second transfer position <NUM>.

The intermediate transfer belt <NUM> is configured to be circumferentially rotatable in the direction of the arrow X with being in contact with or away from the photoconductor <NUM> of each color.

As illustrated in <FIG>, each first transfer unit <NUM> is formed by a contact section between a corresponding photoconductor <NUM>, intermediate transfer belt <NUM>, and first transfer roll <NUM>. The first transfer roll <NUM> is disposed to be opposed to the photoconductor <NUM> with the intermediate transfer belt <NUM> interposed therebetween. The first transfer roll <NUM> and the intermediate transfer belt <NUM> are configured to be in contact with each other with a predetermined load.

In addition, a voltage is applied to the first transfer roll <NUM> by a power supply unit which is not illustrated. The voltage is called a first transfer voltage for first transferring a toner image formed on the photoconductor <NUM> to the intermediate transfer belt <NUM> between the photoconductor <NUM> and the first transfer roll <NUM>.

As illustrated in <FIG>, the transfer body <NUM> is provided at a position opposed to the back-up roll <NUM> with the intermediate transfer belt <NUM> interposed therebetween. The transfer body <NUM> has a cylindrical shape having an axial direction in the depth direction of the image forming apparatus <NUM>, and is provided rotatably in a circumferential direction. In the outer circumference of the transfer body <NUM>, a recess (not illustrated) is formed into which the later-described gripper <NUM> is fitted.

A voltage is applied to the transfer body <NUM> by a power supply unit which is not illustrated. The voltage is called a second transfer voltage when toner images superimposed and transferred on the intermediate transfer belt <NUM> are second transferred to a sheet of paper P which has been transported to the second transfer position <NUM>.

As illustrated in <FIG>, the second transfer position <NUM> (= corresponds to an example of an image formation position) is determined by the contact point between the intermediate transfer belt <NUM> and the transfer body <NUM> formed in a roll shape. The intermediate transfer belt <NUM> is configured to be in contact with the transfer body <NUM> with a predetermined load by the back-up roll <NUM> disposed to be opposed to the transfer body <NUM>.

A fixing device <NUM> is disposed downstream of the second transfer position <NUM> in the transport direction of the sheet of paper P. The fixing device <NUM> is comprised of a pair of rolls which are opposed to each other. The pair of rolls are installed to be opposed to each other with the later-described sheet transport path A interposed therebetween. In other words, the sheet of paper P as a fixing target is transported so as to pass between the pair of rolls.

As illustrated in <FIG>, a sheet transport path A (= an example of a transport path) has a function of transporting a sheet of paper P to the unit 10A, the sheet of paper P being supplied from the sheet trays <NUM> of the unit 10B or the unit 10C. In addition, the sheet transport path A is configured to allow the sheet of paper P supplied from the sheet trays <NUM> to be transported, while being passed through the secondary transfer position <NUM> and the fixing position (the details will be described below) in the unit 10A, and to be discharged to the sheet discharge tray <NUM> of the unit 10C through the unit 10B.

On the other hand, part of the sheet transport path A downstream of the fixing device <NUM> is branched to a direction change path B for changing the transport direction of the sheet of paper P. The direction change path B has a function of changing the transport direction of a sheet of paper P to the direction opposite to the transport direction of the sheet transport path A downstream of the fixing device <NUM>, the sheet of paper P being transported to the direction change path B branched from the sheet transport path A. In other words, the direction change path B has a function of reversing the relationship between the front edge and the rear edge of a sheet of paper P by changing the transport direction of the sheet of paper P transported to the direction change path B, and allowing the sheet of paper P to be transported downstream in the transport direction of the direction change path B. Part of the direction change path B downstream in the transport direction is configured to be merged into the sheet transport path A which leads to the second transfer position <NUM>. The path between the direction change path B and a circumferential path D (the details will be described below) on the sheet transport path A is called a merge path where the transport path for the front surface of the sheet of paper P and the transport path for the rear surface are merged. Note that each transport path mentioned above includes multiple rolls for sheet transport which are not illustrated. The sheet of paper P is transported along each transport path by these rolls.

Next, an overview of the image forming operation for the sheet of paper P in the image forming apparatus <NUM> will be described.

Various types of operations in the image forming apparatus <NUM> are performed by a controller <NUM> (see <FIG>) built in the apparatus. Upon receiving an image forming command from the outside, the controller <NUM> causes each image forming unit <NUM> to operate. The photoconductor <NUM> of each color is charged by the charger <NUM> while being rotated. In addition, the controller <NUM> transmits image data which has undergone image processing in an image signal processor (its illustration is omitted) to each exposure device <NUM>. The exposure device <NUM> radiates exposure light to a corresponding photoconductor <NUM> according to the image data, thereby exposing the charged photoconductor <NUM> to the light. Thus, an electrostatic latent image is formed on the outer circumferential surface of the photoconductor <NUM>. The electrostatic latent image formed on the photoconductor <NUM> is developed by a corresponding developing device <NUM>, and a toner image of each color is formed on the photoconductor <NUM> corresponding to the color.

A toner image of each color formed on a corresponding photoconductor <NUM> of the color is first transferred to the intermediate transfer belt <NUM> by the first transfer roll <NUM> of the color. At this time, due to the circumferential rotation of the intermediate transfer belt <NUM>, toner images of respective colors are successively first transferred to the intermediate transfer belt <NUM> while being superimposed. The toner images superimposed in this manner are transported to the second transfer position <NUM> by the circumferential rotation of the intermediate transfer belt <NUM>. The superimposed toner images are then transferred from the intermediate transfer belt <NUM> to the sheet of paper P at the second transfer position <NUM>.

The sheet of paper P with the second transferred toner images is transported to the fixing device <NUM>. The sheet of paper P is heated and pressurized by a fixing roll in the fixing device <NUM>. Consequently, the toner images formed by the image forming units <NUM> are fixed to the sheet of paper P.

Note that the image forming apparatus <NUM> has the direction change path B, thereby making it possible to perform duplex printing on the sheet of paper P. The details of the duplex printing in the image forming apparatus <NUM> will be described later.

Next, the principal components of the exemplary embodiment will be described.

As illustrated in <FIG>, the image forming apparatus <NUM> includes a gripper <NUM> (= corresponds to an example of a holding unit) that holds the front edge P1 of the transported sheet of paper P to assist the transport of the sheet of paper. Th gripper <NUM> includes clips <NUM>, a rectangular case <NUM> that covers the clips <NUM>, and a shaft <NUM> that extends in the depth direction.

Multiple clips <NUM> are provided along the depth direction of the apparatus. In addition, the clips <NUM> are configured to be fixed to the shaft <NUM>, and rotatable along with the rotation of the shaft <NUM> in a circumferential direction.

The case <NUM> has a longitudinal direction in the depth direction, and is held by the shaft <NUM>. In addition, the case <NUM> is configured to rotate independently from the rotation of the clips <NUM>. Furthermore, the case <NUM> is configured to cover the upstream and downstream sides in two directions of the clips <NUM> in the sheet transport direction, and the side in the back surface direction (in other words, the direction to a non-image formation surface of the sheet of paper P) of the sheet of paper. In this structure, front edges <NUM> of the clips <NUM> and a rear end <NUM> of the case <NUM> are configured to hold the front edge P1 of the sheet of paper P in the transport direction.

As illustrated in <FIG>, both ends of the shaft <NUM> of the gripper <NUM> in the depth direction are held by the later-described transport chains <NUM> (= corresponds to an example of a circumferential rotation unit). In other words, the transport chains <NUM> are mounted on the both ends of the gripper <NUM> in the depth direction. The shaft <NUM> of the gripper <NUM> is held by the transport chains <NUM> so as to circumferentially rotate along with the transport chains <NUM> in conjunction with the circumferential rotation of the transport chains <NUM>. Thus, the gripper <NUM> is held by the transport chains <NUM> provided on the near side and the far side of the image forming apparatus <NUM>, and is circumferentially rotated along a predetermined circumferential rotational path D (see <FIG>). The transport chains <NUM> are a pair of endless-shaped chains held by multiple sprockets (not illustrated) along the circumferential rotational path D.

Here, as illustrated in <FIG>, the circumferential rotational path D is provided so that part of the sheet transport path A overlaps with part of the circumferential rotational path D in a front view of the image forming apparatus <NUM>. In the exemplary embodiment, the posture of the circumferential rotational path D is an approximately triangular shape which is long in the apparatus width direction in a front view, and has a projection downward. Specifically, the circumferential rotational path D is formed so as to overlap with the sheet transport path A in a range from a contact point with the sheet transport path A on the outer circumference of a sprocket <NUM> provided below the transfer body <NUM> to the point passing the fixing device <NUM>. Note that the position at which the fixing device <NUM> is passed by the circumferential rotational path D is called a fixing position (= corresponds to an example of a fixing position).

At the start point of overlap between the sheet transport path A and the circumferential rotational path D, the front edges <NUM> of the clips <NUM> come closer to the rear end <NUM> of the case <NUM>, and the gripper <NUM> grips the front edge of the sheet of paper P. In other words, the start point of the overlap between the sheet transport path A and the circumferential rotational path D is called a start position of holding of the sheet of paper P by the gripper <NUM> on the circumferential rotational path D. The start position of holding of the sheet of paper P by the gripper <NUM> on the circumferential rotational path D is called a pass point D1 (= corresponds to an example of a pass point) at which the sheet of paper P is passed from the sheet transport path A to the gripper <NUM>.

In addition, at the end point of the overlap between the circumferential rotational path D and the sheet transport path A, the front edges <NUM> of the clips <NUM> are separated from the rear end <NUM> of the case <NUM>, and the front edge of the sheet of paper P is released. The position of releasing the sheet of paper P from the gripper <NUM> on the circumferential rotational path D is called a receiving point D2 (= corresponds to an example of a receiving point) at which the sheet of paper P is received by the sheet transport path A from the gripper <NUM>. Note that the pass point D1 is disposed below the receiving point D2.

As illustrated in <FIG>, in the exemplary embodiment, when the sheet of paper P is passed from the sheet transport path A to the circumferential rotational path D, the sheet of paper P is passed from the left side to the right side with respect to the image formation position. In other words, the sheet feed direction at the pass point D1 is such that transport is made from the leftward direction to the rightward direction.

In contrast, when the sheet of paper P is received by the circumferential rotational path D, the sheet of paper P is received from the right side to the left side with respect to the second transfer position <NUM>. In other words, the sheet discharge direction at the receiving point D2 is such that transport is made from the rightward direction to the leftward direction.

In another viewpoint of what has been described, the receiving point D2 and the pass point D1 are both provided on the left side (that is, on the same side) in <FIG> with respect to the second transfer position <NUM> on the circumferential rotational path D. In addition, the sheet feed direction and the sheet discharge direction are set to be opposite directions.

In addition, the direction in which the sheet of paper P passes through the second transfer position <NUM> (that is, the image formation position) on the circumferential rotational path D is provided to be inclined upward from the lower right side to the upper left side.

Of the circumferential rotational path D, the path from the second transfer position <NUM> to the point passing the fixing device <NUM> is formed to be inclined upward. Thus, the position of the fixing device <NUM> is arranged above the position of the second transfer position <NUM>.

Of the circumferential rotational path D, the path from the point passing the fixing device <NUM> (the receiving point D2) to the merge point (the pass point D1) to the sheet transport path A is formed to be inclined downward. The path inclined downward from the receiving point D2 to the pass point D1 is an inclined section DT. With this configuration, the inclined section DT forms space S which is interposed between the inclined section DT and the sheet transport path A. The space S in the exemplary embodiment has a vertical height which is reduced over a range from the receiving point D2 to the pass point D1 in the horizontal direction. In other words, the space S in the exemplary embodiment has a vertical height which is reduced over a range from the fixing device <NUM> to the second transfer position <NUM> in the horizontal direction.

As illustrated in <FIG>, a position adjuster <NUM> is disposed so that part of the upper side thereof is in the space S, and has a function of making position adjustment to the sheet of paper P transported to the pass point D1. Specifically, the position adjuster <NUM> is disposed on the merge path provided between the direction change path B and the pass point D1 on the sheet transport path A.

As illustrated in <FIG>, the position adjuster <NUM> includes multiple rolls <NUM> to <NUM>, multiple sensors <NUM> to <NUM> and a stopper <NUM>. Each roll is disposed on the upper side or the lower side of the sheet transport path A. Specifically, the roll <NUM>, the roll <NUM>, and the roll <NUM> are disposed on the upper side of the merge path in sequence in the transport direction of the sheet of paper P.

In addition, the roll <NUM>, the roll <NUM>, and the roll <NUM> are disposed on the lower side of the merge path so as to form pairs with the roll <NUM>, the roll <NUM>, and the roll <NUM>, respectively. These roll pairs rotate, thereby transporting the sheet of paper P with the sheet of paper P interposed between each upper-side roll and a corresponding lower-side roll. Note that the roll <NUM> is provided separably from the sheet transport path A.

A substantially N-shaped stopper <NUM> is disposed on the near side and the far side in the depth direction at the contact point between the roll <NUM> and the roll <NUM>. The downstream end of the stopper <NUM> in the sheet transport direction is a gate section <NUM> which is bent upward to intersect the sheet transport path A. The front edge P1 of the sheet of paper P supplied to the position adjuster <NUM> is butted against the gate section <NUM>, thus the timing of sheet transport, positional displacement in the sheet width direction or inclination of the sheet is adjusted. Specifically, the position adjuster <NUM> makes positional adjustment to the sheet of paper P transported to the pass point D1 by the gate section <NUM> provided in the pair of the roll <NUM> and the roll <NUM>.

A sector-shaped gear <NUM> and a circular gear <NUM> engaged with the gear <NUM> are provided at an upstream position of the stopper <NUM> in the sheet transport direction. Rotation of a motor (not illustrated) mounted on the gear <NUM> causes the gear <NUM> and the gear <NUM> to rotate, and thus the gate section <NUM> of the stopper <NUM> mounted on the gear <NUM> is moved in the up and down direction in <FIG>.

When the gate section <NUM> is moved upward, the gate section <NUM> is transferred to a position to block the sheet transport path A. In this case, the sheet of paper P transported along the sheet transport path A is prevented from being transported at the position of the gate section <NUM>. On the other hand, when the gate section <NUM> is moved downward, the gate section <NUM> is transported to a position to allow transport of the sheet transport path A. In this case, the sheet of paper P is transported along the sheet transport path A without receiving interference from the gate section <NUM>.

The sensors <NUM> to <NUM> each detect a passing state and a non-passing state of the sheet of paper P transported along the sheet transport path A. The operation of each of the rolls <NUM> to <NUM> is controlled as appropriate by the controller <NUM> which has received a signal from each of the sensors <NUM> to <NUM>.

Note that the position adjuster <NUM> is disposed so as to overlap in position with the inclined section DT of the circumferential rotational path D as viewed in the horizontal direction. In other words, the position adjuster <NUM> is disposed between the fixing device <NUM> and the second transfer position <NUM> in the horizontal direction. In addition, the position adjuster <NUM> is disposed at a position nearer to the pass point D1 than a bisector (its illustration is omitted) in the space S, the bisector dividing the space S into halves, that is, the upstream side and the downstream side in the transport direction to the pass point D1. That is, the rolls <NUM>, <NUM> are disposed at a position nearer to the pass point D1 than a bisector (its illustration is omitted) in the space S, the bisector dividing the space S into halves, that is, the upstream side and the downstream side in the transport direction to the pass point D1. In other words, the gate section <NUM> is disposed at a position nearer to the pass point D1 than a bisector (its illustration is omitted) in the space S, the bisector dividing the space S into halves, that is, the upstream side and the downstream side in the transport direction to the pass point D1. In addition, the position adjuster <NUM> is disposed in the unit 10A where the image former and the transport chains <NUM> are arranged. In short, in the image forming apparatus <NUM>, the image former, the transport chains <NUM> and the position adjuster <NUM> are disposed in the same unit 10A.

<FIG> illustrate the operation of each component in the position adjuster <NUM> when positional adjustment is made to the sheet of paper P. As illustrated in <FIG>, the gate section <NUM> is disposed so as to block the sheet transport path when the sheet of paper P is transported.

As illustrated in <FIG>, the front edge P1 of the sheet of paper P transported along the sheet transport path A passes through the sensor <NUM>. The roll <NUM> and the roll <NUM> are driven during the time starting from the timing of sheet passing detected by the sensor <NUM> until the front edge P1 of the sheet of paper P reaches the gate section <NUM>. Note that whether the front edge P1 of the sheet of paper P reaches the gate section <NUM> is also predicted by the timing of passing of the front edge P1 detected by the sensor <NUM> which is provided on the near side of the gate section <NUM>.

As illustrated in <FIG>, when the front edge P1 of the sheet of paper P reaches the gate section <NUM>, the roll <NUM> and the roll <NUM> are in a state of being apart from each other. Specifically, the lower-side roll <NUM> provided movably in a vertical direction is in a state of being moved downward. The sheet of paper P with the front edge P1 transported to the gate section <NUM> is further transported by the roll <NUM> and the roll <NUM> for a predetermined time.

As illustrated in <FIG>, the sheet of paper P further delivered by the roll <NUM> and the roll <NUM> with the front edge P1 butted against the gate section <NUM> is in a state of bending between the roll <NUM>, the roll <NUM>, and the gate section <NUM>. Thus, inclination of the sheet of paper P in the width direction is corrected by the gate section <NUM>.

As illustrated in <FIG>, after the inclination of the sheet of paper P is corrected, the roll <NUM> is moved upward. Thus, the roll <NUM> and the roll <NUM> are in a state of pinching the front edge P1 of the sheet of paper P. At this time, since the inclination of the front edge P1 of the sheet of paper P is corrected by the gate section <NUM>, the state of corrected inclination is maintained by the roll <NUM> and the roll <NUM>.

As illustrated in <FIG>, with the front edge P1 of the sheet of paper P maintained by the roll <NUM> and the roll <NUM>, the gate section <NUM> is moved downward. At this time, the roll <NUM> and the roll <NUM> are in a stationary state.

As illustrated in <FIG>, after the gate section <NUM> is moved downward, the roll <NUM> and the roll <NUM> are driven, thus the sheet of paper P is transported again. The front edge P1 of the transported sheet of paper P passes through the sensor <NUM> disposed between the roll <NUM> and the roll <NUM>. The front edge P1 of the sheet of paper P is then supplied to the roll <NUM> and the roll <NUM>. Furthermore, the front edge P1 of the sheet of paper P is transported by driving the roll <NUM> and the roll <NUM>. At this time, the sensor <NUM> and the sensor <NUM> detect the timing of passing of the front edge P1 of the sheet of paper P, thus the drive state of the roll <NUM> and the roll <NUM> is controlled.

As illustrated in <FIG>, the sheet of paper P which has passed through the position adjuster <NUM> is gripped by the rear end <NUM> of the case <NUM> and the front edges <NUM> of the clips <NUM> in the gripper <NUM> on the circumference of the sprocket <NUM> in <FIG>. The gripper <NUM> is supplied while being moved along the circumferential rotational path D in synchronization with the timing of transport of the front edge P1 of the sheet of paper P. At this time, as illustrated in <FIG>, the case <NUM> and the clips <NUM> are in an open state.

As illustrated in <FIG>, the gripper <NUM> is configured to be moved along the circumferential rotational path D in synchronization with the timing of transport of the sheet of paper P, and the gap between the case <NUM> and the clips <NUM> is gradually reduced. The front edges <NUM> of the clips <NUM> raise the front edge P1 of the sheet of paper P from the sheet transport path A.

As illustrated in <FIG>, the front edge P1 of the sheet of paper P is further raised by the clips <NUM>, and is passed from the sheet transport path A to the circumferential rotational path D with the front edge P1 gripped by the rear end <NUM> of the case <NUM> and the front edges <NUM> of the clips <NUM>. Subsequently, the sheet of paper P is transported to the circumferential rotational path D by the gripper <NUM>.

As illustrated in <FIG>, after the sheet of paper P is passed to the circumferential rotational path D, the front and back thereof are reversed along the outer circumference of the transfer body <NUM>. Specifically, the transport chains <NUM> along the circumferential rotational path D cause the front and back of the sheet of paper P to be reversed on the circumferential rotational path D. The sheet of paper P is then transported to the second transfer position <NUM> provided on the outer circumference of the transfer body <NUM>. Specifically, the second transfer position <NUM> is designed so that the sheet of paper P passes through the second transfer position <NUM> in the process of reversing the sheet of paper P along the circumferential rotational path D and the outer circumference of the transfer body <NUM>. In other words, the transport chains <NUM> along the circumferential rotational path D pass through the image former in the process of reversing the front and back of the sheet of paper P.

When the sheet of paper P passes through the second transfer position <NUM>, the surface facing the back-up roll <NUM> is called an image formation surface (= front surface). In other words, the sheet of paper P is transported with the back surface facing upward at the position adjuster <NUM> and the pass point D1.

After passing through the fixing device <NUM>, the sheet of paper P is received by the sheet transport path A from the circumferential rotational path D. The branch point between the circumferential rotational path D and the sheet transport path A is called the receiving point D2 (= an example of a receiving point). The gripper <NUM> holding the front edge of the sheet of paper P is released at the receiving point D2, thus the sheet of paper P is received by the sheet transport path A from the circumferential rotational path D.

At the time of duplex printing, after passing through the receiving point D2 and being received by the sheet transport path A, the sheet of paper P is transported to the direction change path B where the transport direction is changed, then is passed through the merge path, and transported to the sheet transport path A toward the second transfer position <NUM>. At this time, the upper and lower surfaces of the following two sheets of paper P are reversed: one sheet of paper P which has undergone transport direction change made by the direction change path B, and moves toward the second transfer position <NUM> through the merge path, and the other sheet of paper P which moves from a supply tray <NUM> toward the second transfer position <NUM> through the merge path. Specifically, the one sheet of paper P is transported with the front surface facing upward, where the one sheet of paper P has undergone transport direction change made by the direction change path B, and moves toward the second transfer position <NUM> through the merge path. The sheet of paper P, which has passed through the merge path and is transported to the sheet transport path A toward the second transfer position <NUM>, is passed to the circumferential rotational path D again at the pass point D1. Then the front and back surfaces of the sheet of paper P are reversed along the outer circumference of the transfer body <NUM>, and the sheet of paper P is transported to the second transfer position <NUM>. At this time, the front surface of the sheet of paper P, facing the back-up roll <NUM> is the rear surface, thus an image is formed on the back surface. In other words, the transport chains <NUM> along the circumferential rotational path D constitute part of a back surface-side transport path for forming an image on the back surface of the sheet of paper P.

Next, the operation of the image forming apparatus according to the first exemplary embodiment of the present disclosure will be described.

As illustrated in <FIG>, in the image forming apparatus <NUM>, the receiving point D2 and the pass point D1 are both provided on the left side (that is, on the same side) with respect to the second transfer position <NUM> (that is, the image formation position) on the circumferential rotational path D. In this configuration, the overall apparatus can be downsized, as compared with a configuration in which the receiving point D2 and the pass point D1 are provided on different sides with respect to the image formation position.

In addition, in the image forming apparatus <NUM>, the pass point D1 is provided below the receiving point D2. In this configuration, the transport path (that is, the sheet discharge path) leading to the sheet discharge tray <NUM> provided downstream of the pass point D1 on the sheet transport path A is likely to be disposed above the transport path (that is, the sheet feed path) provided from the sheet trays <NUM> in the image forming apparatus <NUM>. In this configuration, when the sheet discharge tray <NUM> is disposed at a high position in the image forming apparatus <NUM>, and the sheet trays <NUM> are disposed at a low position, a height adjustment transport path for adjustment of the above transport paths is unnecessary.

In addition, the circumferential rotational path D of the image forming apparatus <NUM> is provided so that the direction of passing of the sheet of paper P through the second transfer position <NUM> (that is, the image formation position) is inclined upward from the lower right side to the upper left side. Thus, the overall apparatus in the horizontal direction can be downsized, as compared with when the passage direction of the sheet of paper P is set to the horizontal direction. More particularly, the members provided at the second transfer position <NUM> can be disposed in a diagonal direction, thus the horizontal width of the members can be made shorter than the transport distance of the relevant members. In this configuration, even when a transfer belt transfer device or an ink jet image former is disposed at the second transfer position <NUM>, due to a similar reason, the length of the overall device in the horizontal direction can be made shorter than the transport distance of the recording medium.

In the image forming apparatus <NUM>, the position of the fixing device <NUM> is placed above the second transfer position <NUM>. In this configuration, the heat generated in the fixing device <NUM> is unlikely to be transmitted to the second transfer position <NUM>, as compared with a configuration in which the fixing device <NUM> is disposed below the second transfer position <NUM>. In addition, in this configuration, a longer distance of the transport path can be ensured with respect to the horizontal distance of the transport path between the second transfer position <NUM> and the fixing device <NUM>. Thus, the space to arrange a preliminary fixing device for performing preliminary fixing, and a neutralization device for performing a neutralization process to improve image quality can be ensured between the second transfer position <NUM> and the fixing device <NUM>.

In the image forming apparatus <NUM>, the position adjuster <NUM> is disposed between the fixing device <NUM> and the second transfer position <NUM> in the horizontal direction. Thus, in the image forming apparatus <NUM>, the overall apparatus in the horizontal direction can be downsized, as compared with when the position adjuster <NUM> is disposed outside the range between the fixing device <NUM> and the second transfer position <NUM> in the horizontal direction.

In the image forming apparatus <NUM>, the image former, the transport chains <NUM> and the position adjuster <NUM> are disposed in the same unit 10A. In a comparative example in which the position adjuster <NUM> is disposed in the unit 10B, for adjustment of the position adjuster <NUM> accompanying installation of the image forming apparatus <NUM>, the adjustment needs to be made in consideration of the accuracy of installation of the unit 10B with respect to the unit 10A. In contrast, in the image forming apparatus <NUM>, the image former, the transport chains <NUM> and the position adjuster <NUM> are disposed in the same unit 10A, thus for adjustment of the position adjuster <NUM>, it is not necessary to consider the accuracy of installation of the unit 10B with respect to the unit 10A. Thus, in the image forming apparatus <NUM>, the adjustment of the position adjuster <NUM> at the time of installation of the image forming apparatus <NUM> can be simplified, as compared with the above-mentioned comparative example.

In the image forming apparatus <NUM>, the circumferential rotational path D has the inclined section DT which is inclined downward from the receiving point D2 to the pass point D1. The image forming apparatus <NUM> has a configuration in which the position adjuster <NUM> is disposed in the space S interposed between the inclined section DT and the sheet transport path A. In this configuration, the distance between the position adjuster <NUM> and the pass point D1 is reduced, as compared with a configuration in which the position adjuster <NUM> is disposed upstream of the space S in the transport direction of the sheet of paper P. In this manner, the shorter the distance between the position adjuster <NUM> and the pass point D1, the lower the possibility of occurrence of error in the accuracy of sheet transport. Thus, in the image forming apparatus <NUM>, the positional accuracy of the sheet of paper P transported to the pass point D1 is increased, as compared with a configuration in which the position adjuster <NUM> is disposed upstream of the space S in the transport direction of the sheet of paper P. Thus, in the image forming apparatus <NUM>, the accuracy of position for holding the sheet of paper P by the gripper <NUM> is improved, as compared with a configuration in which the position adjuster <NUM> is disposed upstream of the space S in the transport direction of the sheet of paper P.

The image forming apparatus <NUM> has a configuration in which the transport chains <NUM> are mounted on both axial ends of the gripper <NUM>. Thus, inclination of the recording medium in the width direction can be reduced, as compared with a configuration in which a transport chain <NUM> is mounted only on a central portion of the gripper <NUM> in the axial direction.

The image forming apparatus <NUM> has a configuration in which the transport chains <NUM> along the circumferential rotational path D cause the front and back of the sheet of paper P to be reversed on the circumferential rotational path D. In this configuration, the overall apparatus can be downsized, as compared with a configuration in which a path that causes the front and back of the sheet of paper P to be reversed is provided separately from the circumferential rotational path D.

The image forming apparatus <NUM> has a configuration in which the transport chains <NUM> along the circumferential rotational path D pass through the image former in the process of reversing the front and back of the sheet of paper P. In this configuration, the overall apparatus can be downsized, as compared with a configuration in which a front and back of sheet reversal path is provided separately from the circumferential rotational path D (that is, part of the sheet transport path A).

In the image forming apparatus <NUM>, the transport chains <NUM> along the circumferential rotational path D configurates part of a back surface-side transport path for forming an image on the back surface of the sheet of paper P. In this configuration, the overall apparatus can be downsized, as compared with a configuration in which the circumferential rotation unit and the back surface-side transport path are separately provided.

In the image forming apparatus <NUM>, the position adjuster <NUM> is disposed in the merge path provided between the direction change path B and the pass point D1 on the sheet transport path A. In this configuration, the overall apparatus can be downsized, as compared with a configuration in which the merge path and the position adjuster <NUM> are separately provided. In this configuration, positional adjustment at the time of front surface transport of the sheet of paper P and positional adjustment at the time of back surface transport can be made by the position adjuster <NUM> in common. In other words, in the image forming apparatus <NUM>, the position adjuster <NUM> serves as both a position adjuster for front surface transport and a position adjuster for back surface transport. Thus, in this configuration, the overall apparatus can be downsized, as compared with a configuration in which a position adjuster for front surface transport and a position adjuster for back surface transport are separately provided.

Next, an image forming apparatus <NUM> according to a second exemplary embodiment of the present disclosure will be described with reference to <FIG>. This embodiment is not covered by the claims but it serves a better understanding of the invention. The image forming apparatus <NUM> according to the second exemplary embodiment is a modification of the image forming apparatus according to the first exemplary embodiment, thus a redundant content is labeled with the same or a related number as appropriate, and a description is omitted.

As illustrated in <FIG>, the image forming apparatus <NUM> includes: a unit 110A disposed at the center in the right and left direction of <FIG>; a unit 110B disposed on the right side; and a unit 110C disposed on the left side.

The sheet transport path A in the image forming apparatus <NUM> is configured to pass through the unit 110B, the unit 110A, and the unit 10C sequentially. Thus, the sheet of paper P transported along the sheet transport path A is supplied from a sheet tray <NUM> disposed in the unit 110B and discharged to the unit 110C through the unit 110A.

Here, in the exemplary embodiment, the image formation surface of a sheet of paper P is the upper surface side when the sheet is stored in a sheet tray <NUM>. In other words, the sheet of paper P in a state of being stored in the sheet tray <NUM> is transported to the second transfer position <NUM> without being reversed.

On the other hand, at the time of duplex printing, when an image is formed on the back surface-side of the image formation surface of the sheet of paper P, the sheet of paper P is transported along the direction change path B provided in the unit 110C and the unit 110A, and after the transport direction is changed, the sheet of paper P is supplied to the circumferential rotational path D again. Thus, the direction change path B and the circumferential rotational path D constitute a back surface-side transport path for forming an image on the back surface of the sheet of paper P. In other words, the circumferential rotational path D constitutes part of the back surface-side transport path.

The circumferential rotational path D of the image forming apparatus <NUM> is disposed in the right and left direction in <FIG> with respect to the second transfer position <NUM>. At the time of front surface transport of the sheet of paper P, the pass point D1 at which the sheet of paper P is passed from the sheet transport path A to the circumferential rotational path D is disposed on the right side in <FIG> with respect to the second transfer position <NUM>. In addition, the receiving point D2 at which the sheet of paper P is received by the sheet transport path A from the circumferential rotational path D is disposed on the left side in <FIG> with respect to the second transfer position <NUM>. In contrast, at the time of back surface transport of the sheet of paper P, a re-receiving point D2 at which the sheet of paper P is passed again from the direction change path B to the circumferential rotational path D is disposed on the left side in <FIG> with respect to the second transfer position <NUM>.

The image forming apparatus <NUM> includes a position adjuster 50A and a position adjuster 50B. The position adjuster 50A is disposed upstream in the sheet transport direction relative to a merge position from the sheet transport path A to the circumferential rotational path D. In contrast, the position adjuster 50B is disposed upstream in the sheet transport direction relative to a merge position from the direction change path B to the circumferential rotational path D.

The position adjuster 50A is in charge of position adjustment at the time of transport for image formation on the front surface of the sheet of paper P. In contrast, the position adjuster 50B is in charge of position adjustment at the time of transport for image formation on the back surface of the sheet of paper P.

Hereinafter, the operational effect of the image forming apparatus <NUM> according to the second exemplary embodiment of the present disclosure will be described.

As illustrated in <FIG>, in the image forming apparatus <NUM>, when an image is formed on the front surface of the sheet of paper P, then an image is formed on the back surface, the front and back of the sheet of paper P are reversed at the right end of the circumferential rotational path D. That is, the circumferential rotational path D includes part of the transport path for back surface-side of the sheet of paper. In this configuration, the overall apparatus can be downsized, as compared with a configuration in which the transport path for back surface-side of the sheet of paper and the circumferential rotational path D are separately provided.

In the image forming apparatus <NUM>, the sprocket <NUM> is disposed on the right side in <FIG> with respect to the second transfer position <NUM> so that an image is formed in the process of reversing the front and back of the sheet of paper on the circumferential rotational path D. In this configuration, the overall apparatus can be downsized, as compared with a configuration in which a front and back of sheet reversal path is provided separately from the circumferential rotational path D (that is, part of the sheet transport path A).

In the image forming apparatus <NUM>, the pass point D1 is disposed below the receiving point D2. In this configuration, when the sheet discharge tray <NUM> is disposed at a high position in the image forming apparatus <NUM>, and the sheet trays <NUM> are disposed at a low position, a height adjustment transport path for unnecessary adjustment of the above transport paths can be eliminated.

Although the image forming apparatus according to each of the exemplary embodiments has been described, the present disclosure may be implemented in various aspects in a range not departing from the gist of the present disclosure.

For example, in the exemplary embodiments, a system of image formation on a sheet of paper P has been explained using an electrophotographic system as an example. However, without being limited to this, for example, an ink jet system and an offset printing system may be used.

In the exemplary embodiments, the sheet transport direction and the layout of the components are each an example, and may be changed as appropriate. For example, in the exemplary embodiments, the sheet transport path A may be laid out with the right and left directions reversed.

In addition, the sheet trays <NUM> that supply a sheet of paper P to the sheet transport path A may be provided on both right and left sides of the unit 10A or 110A which includes the image former.

In the exemplary embodiments described above, the gripper <NUM> has been illustrated to physically hold the front edge of a sheet of paper. However, without being limited to this structure, the gripper <NUM> may hold the front edge of the sheet of paper P by an air suction power, for example.

Claim 1:
An image forming apparatus (<NUM>) comprising:
a holding unit (<NUM>) that holds a recording medium (P) transported;
a circumferential rotation unit (<NUM>) that circumferentially rotates with the holding unit (<NUM>) fixed, and constitutes part of a transport path (A) along which the recording medium (P) is transported;
an image former (<NUM>, <NUM>, <NUM>) that forms an image on the recording medium (P) at an image formation position (<NUM>) on a circumferential rotational path (D) of the circumferential rotation unit (<NUM>);
a pass point (D1) at which the recording medium (P) is passed on the circumferential rotational path (D); and
a receiving point (D2) which is provided on a same side as the pass point (D1) with respect to the image formation position (<NUM>), and at which the recording medium (P) is received from the circumferential rotational path (D),
the image forming apparatus (<NUM>) being characterized in that:
the circumferential rotational path (D) is configured to pass through a fixing unit (<NUM>) that fixes an image to the recording medium (P) at a fixing position provided downstream of the image former (<NUM>, <NUM>, <NUM>), and
the fixing position is placed above the image formation position (<NUM>) on the circumferential rotational path (D).